193 results on '"food web dynamics"'
Search Results
2. High importance of indirect evolutionary rescue in a small food web.
- Author
-
van Velzen, Ellen
- Subjects
- *
FOOD chains - Abstract
Evolutionary rescue may allow species to survive environmental change, but how this mechanism operates in food webs is poorly understood. Here, the evolutionary rescue was investigated in a small model food web, systematically allowing the evolution of each single species in order to reveal how its adaptation affects the persistence of itself and others. The impact of evolution was highly species‐specific and not necessarily positive: only one species, the specialist predator, consistently had a positive impact on overall persistence. Most strikingly, evolution overwhelmingly affected other species: rescue of others (indirect rescue) was far more frequent than self‐rescue, and negative effects were nearly always indirect. This demonstrates that evolutionary rescue in food webs is inextricably bound up with species interactions, as the effects of evolution in one species ripple through the entire community. It is therefore critically important to consider the food web context in efforts to understand how species may survive global change. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
3. Ecological interruption on food web dynamics by eutrophic water discharge from the world’s longest dike at Saemangeum, Yellow Sea
- Author
-
In Ok Lee, Hosang Kim, Inha Kwon, Bong-Oh Kwon, Jae-Sung Kim, Junghyun Lee, Jungho Nam, Junsung Noh, and Jong Seong Khim
- Subjects
Food web dynamics ,Microphytobenthos ,Organic matters ,Benthos ,Sea dike ,Eutrophication ,Environmental sciences ,GE1-350 - Abstract
The man-made sea dike has disrupted the natural link between riverine and marine ecosystems and caused eutrophication within the aquatic ecosystem. The eutrophic water discharge has also raised concerns. As a representative tidal flat with the longest dike in the world, Saemangeum has experienced the problem of eutrophication. To elucidate the discharge water effects on the benthic food web dynamics, a four-year round sampling was conducted in/outside of the Saemangeum sea dike. Stable isotope analysis was applied to benthos (a total of 54 species) and their potential diets. Water discharge tripled in period II (2021–2022) compared to the period I (2019–2020). However, there were no significant impact changes in food web structure between the two periods due to improved lake water quality in period II. A positive correlation of nutrient concentration between the inner and outer areas of the dike revealed a direct effect of the water discharge on the outer tidal flat. The water discharge altered the spatial environmental conditions and the food web structure of the outer tidal flat. High TN concentrations stimulated the biomass of microphytobenthos (MPB) near the water gates, which in turn increased MPB consumption by benthos, demonstrating the in/direct impacts of water discharge on the food web. Furthermore, filter feeders exhibited a more sensitive response to spatial organic matter distribution compared to deposit feeders in diet utilization. Overall, our novel findings on food web dynamics in a representative tidal flat with artificial structures emphasize the necessity of continuous monitoring to ensure the sustainability of coastal ecosystems.
- Published
- 2024
- Full Text
- View/download PDF
4. High resolution temporal data shows how increasing prey availability reduces early season intraguild predation and pest spread in cereal crops.
- Author
-
Branco Leote, Pedro Nuno, Rennstam Rubbmark, Oskar Ragnar, and Traugott, Michael
- Subjects
- *
PREY availability , *PREDATION , *PESTS , *FOOD chains , *PLANT parasites - Abstract
• Intraguild predation within beetle communities was analysed in cereal fields. • Organic fertilization increased non-pest prey and lowered intraguild predation. • Lower intraguild predation correlated with lower pest spread, but not density. • No effect of organic fertilization was found on pest density or consumption. • Fertilization effects may offset pest predation from lower predator interference. Intraguild predation is an extreme form of competition, that depends on resource availability, niche overlap, behaviour and diversity. However, despite modelling and mesocosm experiments, field studies are scarce, and we know nothing of its temporal dynamics within real-world food webs, particularly in the context of biological control. To address this, we added manure to cereal fields to increase decomposer prey, and analysed the diet of over 6000 predators over the entire cropping season during two consecutive years. Our results show that manure increased available prey temporarily and reduced intraguild predation. With this organic fertilization, a reduction in pest spread between tillers within fields correlated with lower intraguild predation, while pest density remained unchanged across treatments, making the net effect on biological control unclear. We hypothesize that the mechanism responsible for why lowering intraguild predation reduces pest spread are changes in predator behaviour, that allow predators to exert more pressure on pests. Conversely, the absence of an effect on pest density may be linked to other effects of fertilization, such as increased pest and plant growth counteracting any increase in predation pressure. The high temporal resolution of our data showed how dynamic IGP is throughout the season, which stresses the importance of studying food webs over time, to generate a mechanistic understanding of biological control. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
5. Seasonal Dynamics of Lake Winnipeg's Microbial Communities Reveal Aerobic Anoxygenic Phototrophic Populations Coincide with Sunlight Availability.
- Author
-
Kuzyk, Steven B., Ma, Xiao, and Yurkov, Vladimir
- Abstract
In this first comprehensive study of Lake Winnipeg's microbial communities, limnetic and littoral euphotic zones were examined during each season from 2016 through 2020. Classical cultivation and modern high-throughput sequencing techniques provided quantification and identification of key phototrophic populations, including aerobic anoxygenic phototrophs (AAP). Annual dynamics found total heterotrophs reached 4.23 × 10
6 CFU/g in littoral sands, and 7.69 × 104 CFU/mL in summer littoral waters on oligotrophic media, higher counts than for copiotrophic compositions. Limnetic numbers inversely dipped to 4.34 × 103 CFU/mL midsummer. Cultured AAP did not follow heterotrophic trends, instead peaking during the spring in both littoral and limnetic waters as 19.1 and 4.7% of total copiotrophs, or 3.9 and 4.9% of oligotrophs, decreasing till autumn each year. Complementary observations came from environmental 16S V4 rRNA gene analysis, as AAP made up 1.49 and 1.02% of the littoral and limnetic sequenced communities in the spring, declining with seasonal progression. Spatial and temporal fluctuations of microbes compared to environmental factors exposed photosynthetic populations to independently and regularly fluctuate in the ecosystem. Oxygenic phototrophic numbers expectantly matched the midsummer peak of Chl a and b, oxygenic photosynthesis related carbon fixation, and water temperature. Independently, AAP particularly colonized spring littoral areas more than limnetic, and directly corresponded to habitat conditions that specifically promoted growth: the requirement of light and organic material. [ABSTRACT FROM AUTHOR]- Published
- 2022
- Full Text
- View/download PDF
6. Integrating terrestrial scavenging ecology into contemporary wildlife conservation and management.
- Author
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Patterson, Jessica R., DeVault, Travis L., and Beasley, James C.
- Subjects
- *
WILDLIFE management , *WILDLIFE conservation , *ANIMAL ecology , *ECOSYSTEM health , *ENVIRONMENTAL health , *ECOSYSTEMS , *ANIMAL populations - Abstract
Scavenging plays a vital role in maintaining ecosystem health and contributing to ecological functions; however, research in this sub‐discipline of ecology is underutilized in developing and implementing wildlife conservation and management strategies. We provide an examination of the literature and recommend priorities for research where improved understanding of scavenging dynamics can facilitate the development and refinement of applied wildlife conservation and management strategies. Due to the application of scavenging research broadly within ecology, scavenging studies should be implemented for informing management decisions. In particular, a more direct link should be established between scavenging dynamics and applied management programs related to informing pharmaceutical delivery and population control through bait uptake for scavenging species, prevention of unintentional poisoning of nontarget scavenging species, the epidemiological role that scavenging species play in disease dynamics, estimating wildlife mortalities, nutrient transfer facilitated by scavenging activity, and conservation of imperiled facultative scavenging species. This commentary is intended to provide information on the paucity of data in scavenging research and present recommendations for further studies that can inform decisions in wildlife conservation and management. Additionally, we provide a framework for decision‐making when determining how to apply scavenging ecology research for management practices and policies. Due to the implications that scavenging species have on ecosystem health, and their overall global decline as a result of anthropic activities, it is imperative to advance studies in the field of scavenging ecology that can inform applied conservation and management programs. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
7. Integrating terrestrial scavenging ecology into contemporary wildlife conservation and management
- Author
-
Jessica R. Patterson, Travis L. DeVault, and James C. Beasley
- Subjects
ecosystem health ,food web dynamics ,scavenging ecology ,wildlife conservation ,wildlife diseases ,wildlife management ,Ecology ,QH540-549.5 - Abstract
Abstract Scavenging plays a vital role in maintaining ecosystem health and contributing to ecological functions; however, research in this sub‐discipline of ecology is underutilized in developing and implementing wildlife conservation and management strategies. We provide an examination of the literature and recommend priorities for research where improved understanding of scavenging dynamics can facilitate the development and refinement of applied wildlife conservation and management strategies. Due to the application of scavenging research broadly within ecology, scavenging studies should be implemented for informing management decisions. In particular, a more direct link should be established between scavenging dynamics and applied management programs related to informing pharmaceutical delivery and population control through bait uptake for scavenging species, prevention of unintentional poisoning of nontarget scavenging species, the epidemiological role that scavenging species play in disease dynamics, estimating wildlife mortalities, nutrient transfer facilitated by scavenging activity, and conservation of imperiled facultative scavenging species. This commentary is intended to provide information on the paucity of data in scavenging research and present recommendations for further studies that can inform decisions in wildlife conservation and management. Additionally, we provide a framework for decision‐making when determining how to apply scavenging ecology research for management practices and policies. Due to the implications that scavenging species have on ecosystem health, and their overall global decline as a result of anthropic activities, it is imperative to advance studies in the field of scavenging ecology that can inform applied conservation and management programs.
- Published
- 2022
- Full Text
- View/download PDF
8. Resource overlap and infrequent predation on key pests show vulnerability in cotton biological control services.
- Author
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Schmidt, Jason M., Russell, Katherine, Bowers, Carson, Coffin, Alisa W., Thompson, Melissa, Grabarczyk, Erin E., Tillman, P. Glynn, and Olson, Dawn
- Subjects
- *
STINKBUGS , *PESTS , *BIOTIC communities , *ALEYRODIDAE , *PEST control , *AGRICULTURAL intensification - Abstract
Promoting arthropod biodiversity to increase ecosystem services through ecological intensification is a challenge for agriculture. And recent evidence suggests that standard pesticide applications not only harm natural enemies but may also fail to deliver long-term pest control solutions. To fuel ecological intensification and build predictive frameworks for pest management incorporating estimates of pest abundance, natural enemy abundance and their associated interactions is essential. Within this framework, there is a need to shift the focus from a single pest and predator to consider the community of predatory arthropods that interact with communities of prey. We took a network-based approach to investigate community interactions of predatory arthropods that feed on key pests and alternative prey in cotton over a three-year period. We merged prey activity, generalist predator communities collected from cotton canopies, and reconstructed trophic interactions with DNA detection frequencies estimated from molecular gut content analysis. Overall, many predator diets overlap, resulting in similar foraging patterns on groups of cotton pests. Moreover, predation on key cotton pests, such as stink bugs and white flies, was low. Therefore, ecological intensification that increases specialized arthropod predators within the community should improve biological control service delivery. • Predatory arthropod communities and associated prey communities are dynamic over a season and between years. • Crop stages contain dissimilar predatory communities for biological services. • Gut analysis and network estimates of predators shows overlap in biological services. • Aphids appear to provide food for many predator species. • Whiteflies and stink bugs in cotton represent weaknesses in natural pest regulation. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
9. Stable isotopes demonstrate seasonally stable benthic‐pelagic coupling as newly fixed nutrients are rapidly transferred through food chains in an estuarine fish community.
- Author
-
Cobain, Matthew R. D., McGill, Rona A. R., and Trueman, Clive N.
- Abstract
Seasonal differences in the availability of resources potentially result in the food web architecture also varying through time. Stable isotope analyses are a logistically simple but powerful tool for inferring trophic interactions and food web structure, but relatively few studies quantify seasonal variations in the food web structure or nutrient flux across multiple trophic levels. We determined the temporal dynamics in stable isotope compositions (carbon, nitrogen and sulphur) of a fish community from a highly seasonal, temperate estuary sampled monthly over a full annual cycle. Sulphur isotope values in fish tissues discriminated among consumers exploiting pelagic and benthic resources but showed no seasonal variation. This implied limited change in the relative consumption of pelagic and benthic resources by the fish community over the study period despite major seasonal changes in phytoplankton biomass. Conversely, carbon and nitrogen isotope values exhibited seasonality marked by the commencement of the spring phytoplankton bloom and peak chlorophyll concentration, with δ13C values following expected trends in phytoplankton growth physiology and variation in δ15N values coinciding with changes in major nitrogen sources to plankton between nitrate and ammonium. Isotope shifts in fish muscle were detected within 2 weeks of the peak spring phytoplankton bloom, suggesting a rapid trophic transfer of carbon and nitrogen along food chains within the estuarine food web during periods of high production. Therefore we caution against the assumption that temporal averaging effectively dampens isotopic variability in tissues of higher trophic‐level animals in highly dynamic ecosystems, such as temperate estuaries. This work highlights how stable isotope analyses can be combined with environmental data to gain a broader understanding of ecosystem functioning, while emphasising the need for temporally appropriate sampling in stable isotope‐based studies. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
10. Seasonal hydrology influences energy channels in food webs of rivers in the lower Okavango Delta.
- Author
-
Bokhutlo, Thethela, Keppeler, Friedrich W., and Winemiller, Kirk O.
- Subjects
SEASONS ,CALORIC content of foods ,HYDROLOGY ,FOOD chains ,STABLE isotopes ,FISH populations ,ECOSYSTEMS - Abstract
Floodplain aquatic ecosystems experience temporal changes in basal production sources and inputs from allochthonous sources that influence energy flow. We analyzed stable isotope ratios of carbon (δ
13 C) and nitrogen (δ15 N) from 449 fish muscles representing 18 species to characterize energy pathways in two rivers of the lower Okavango Delta, Botswana. We sampled fish during wet and dry seasons and used mixing models to estimate proportions of major basal production sources assimilated by fishes. We estimated trophic position (TP) for each fish population and assessed the association between TP and the degree that fish biomass was supported by a single production source. During the wet season, fishes in the Boteti River assimilated material through food chains originating mainly from aquatic macrophytes. During the dry season, terrestrial C3 plants and terrestrial C4 grasses assumed greater importance. In the Boro River, terrestrial C3 plants were inferred to be an important production source supporting fishes during the wet season, with aquatic macrophytes becoming more important during the dry season. In both rivers and seasons, the degree of dependence on a single source was negatively related to TP, supporting the hypothesis that organisms positioned higher in the food web tend to be supported by multiple food chains and basal sources, whereas organisms lower in the food web may be supported by many or few food chains. We showed that consumers in river food webs shift foraging habits in response to seasonal patterns of connectivity and habitat availability, thus promoting long-term population and community stability. [ABSTRACT FROM AUTHOR]- Published
- 2021
- Full Text
- View/download PDF
11. Seasonal Dynamics of Lake Winnipeg’s Microbial Communities Reveal Aerobic Anoxygenic Phototrophic Populations Coincide with Sunlight Availability
- Author
-
Steven B. Kuzyk, Xiao Ma, and Vladimir Yurkov
- Subjects
microbial ecology of lakes ,aerobic anoxygenic phototrophs ,bacterial community ,Lake Winnipeg ,food web dynamics ,picoplankton ,Biology (General) ,QH301-705.5 - Abstract
In this first comprehensive study of Lake Winnipeg’s microbial communities, limnetic and littoral euphotic zones were examined during each season from 2016 through 2020. Classical cultivation and modern high-throughput sequencing techniques provided quantification and identification of key phototrophic populations, including aerobic anoxygenic phototrophs (AAP). Annual dynamics found total heterotrophs reached 4.23 × 106 CFU/g in littoral sands, and 7.69 × 104 CFU/mL in summer littoral waters on oligotrophic media, higher counts than for copiotrophic compositions. Limnetic numbers inversely dipped to 4.34 × 103 CFU/mL midsummer. Cultured AAP did not follow heterotrophic trends, instead peaking during the spring in both littoral and limnetic waters as 19.1 and 4.7% of total copiotrophs, or 3.9 and 4.9% of oligotrophs, decreasing till autumn each year. Complementary observations came from environmental 16S V4 rRNA gene analysis, as AAP made up 1.49 and 1.02% of the littoral and limnetic sequenced communities in the spring, declining with seasonal progression. Spatial and temporal fluctuations of microbes compared to environmental factors exposed photosynthetic populations to independently and regularly fluctuate in the ecosystem. Oxygenic phototrophic numbers expectantly matched the midsummer peak of Chl a and b, oxygenic photosynthesis related carbon fixation, and water temperature. Independently, AAP particularly colonized spring littoral areas more than limnetic, and directly corresponded to habitat conditions that specifically promoted growth: the requirement of light and organic material.
- Published
- 2022
- Full Text
- View/download PDF
12. Ecological interruption on food web dynamics by eutrophic water discharge from the world's longest dike at Saemangeum, Yellow Sea.
- Author
-
Ok Lee, In, Kim, Hosang, Kwon, Inha, Kwon, Bong-Oh, Kim, Jae-Sung, Lee, Junghyun, Nam, Jungho, Noh, Junsung, and Seong Khim, Jong
- Subjects
- *
TIDAL flats , *FOOD chains , *STABLE isotope analysis , *MARINE ecology , *WATER quality , *BIOMASS - Abstract
[Display omitted] • Confirmed the world's longest man-made dike impact on tidal flat food web dynamics. • Revealed eutrophic water discharge impact on the nutritional and microalgal distribution. • Characterized the greater MPB contribution to benthos by eutrophic water input. • Identified distinct discharge water impact on diet utilization of filter/deposit feeders. The man-made sea dike has disrupted the natural link between riverine and marine ecosystems and caused eutrophication within the aquatic ecosystem. The eutrophic water discharge has also raised concerns. As a representative tidal flat with the longest dike in the world, Saemangeum has experienced the problem of eutrophication. To elucidate the discharge water effects on the benthic food web dynamics, a four-year round sampling was conducted in/outside of the Saemangeum sea dike. Stable isotope analysis was applied to benthos (a total of 54 species) and their potential diets. Water discharge tripled in period II (2021–2022) compared to the period I (2019–2020). However, there were no significant impact changes in food web structure between the two periods due to improved lake water quality in period II. A positive correlation of nutrient concentration between the inner and outer areas of the dike revealed a direct effect of the water discharge on the outer tidal flat. The water discharge altered the spatial environmental conditions and the food web structure of the outer tidal flat. High TN concentrations stimulated the biomass of microphytobenthos (MPB) near the water gates, which in turn increased MPB consumption by benthos, demonstrating the in/direct impacts of water discharge on the food web. Furthermore, filter feeders exhibited a more sensitive response to spatial organic matter distribution compared to deposit feeders in diet utilization. Overall, our novel findings on food web dynamics in a representative tidal flat with artificial structures emphasize the necessity of continuous monitoring to ensure the sustainability of coastal ecosystems. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
13. Diet of the Gopher Rockfish (Sebastes carnatus) Inside and Outside of Marine Protected Areas in Central California
- Author
-
Loury, Erin K.
- Subjects
Marine Protected Areas ,gopher rockfish ,Sebastes carnatus ,food web dynamics ,central California MPAs - Abstract
Marine protected areas (MPAs) can potentially impact food web dynamics by increasing the density of predatory fishes within their borders. Such increases in density can cause shifts in the prey use of generalist predators. This study investigated the effects of increased conspecific density on the diet of Gopher Rockfish (Sebastes carnatus) at a 35-year-old MPA at Point Lobos and four newly established central California MPAs at Año Nuevo, Point Lobos, Piedras Blancas, and Point Buchon. Analysis of 710 stomachs collected in 2007-2009 indicated the most important overall prey were crabs, especially the family Pisidae and genus Cancer, as well as brittle stars and mysids. Diets did not differ inside versus outside the old Point Lobos MPA in terms of prey richness, evenness, composition, or Gopher Rockfish trophic level. Individual specialization, however, was greater outside the MPA. No consistent differences in these metrics were observed inside versus outside the four new MPAs, although prey evenness and composition did differ significantly among geographic locations. Diets at Año Nuevo, the most northern and shallow collection location, were dominated by Cancer crabs and porcelain crabs, while diets from southern, deeper locations were dominated by brittle stars. The case study of the old Point Lobos MPA indicates that changes in fish feeding ecology in MPAs may take decades to occur, if at all. Differences in prey observed among geographic locations suggest variation in the community composition among central California’s new MPAs, which may influence the effect of each MPA on food web dynamics over time.
- Published
- 2011
14. Fishing triggers trophic cascade in terms of variation, not abundance, in an allometric trophic network model
- Author
-
Silva Uusi-Heikkilä, Tommi Perälä, and Anna Kuparinen
- Subjects
0106 biological sciences ,ecosystem stability ,trophic interaction ,010604 marine biology & hydrobiology ,vesiekosysteemit ,variation cascade ,tehokalastus ,Aquatic Science ,010603 evolutionary biology ,01 natural sciences ,fisheries-induced trophic cascade ,kalatalous ,food web dynamics ,14. Life underwater ,biomassa (ekologia) ,ravintoketjut ,ravintoverkot ,Ecology, Evolution, Behavior and Systematics - Abstract
Trophic cascade studies often rely on linear food chains instead of complex food webs and are typically measured as biomass averages, not as biomass variation. We study trophic cascades propagating across a complex food web including a measure of biomass variation in addition to biomass average. We examined whether different fishing strategies induce trophic cascades and whether the cascades differ from each other. We utilized an allometric trophic network (ATN) model to mechanistically study fishing-induced changes in food web dynamics. Different fishing strategies did not trigger traditional, reciprocal trophic cascades, as measured in biomass averages. Instead, fishing triggered a variation cascade that propagated across the food web, including fish, zooplankton and phytoplankton species. In fisheries that removed a large amount of top-predatory and cannibalistic fish, the biomass oscillations started to decrease after fishing was started. In fisheries that mainly targeted large planktivorous fish, the biomass oscillations did not dampen but slightly increased over time. Removing species with specific ecological functions might alter the food web dynamics and potentially affect the ecological resilience of aquatic ecosystems.
- Published
- 2022
15. Assimilation of marine-derived nutrients from anadromous Rainbow Smelt in an eastern North American riverine food web: evidence from stable-isotope and fatty acid analysis.
- Author
-
Landsman, Sean J., Samways, Kurt M., Hayden, Brian, Knysh, Kyle M., and Heuvel, Michael R. van den
- Subjects
- *
RAINBOW smelt , *FOOD chains , *STABLE isotopes , *MARINE ecology , *WETLANDS - Abstract
Movement of anadromous fishes from marine to freshwater habitats provides a seasonal pulse of marine-derived nutrients (MDNs) to freshwater biota. In northeastern North America, iteroparous, anadromous Rainbow Smelt (Osmerus mordax Mitchell, 1814) migrate in high densities to freshwater spawning grounds in early spring. To assess whether 1) MDNs from migratory Rainbow Smelt were incorporated into multiple trophic levels and 2) total fatty acid (FA) compositions of Brook Trout changed during the Rainbow Smelt migration, we compared stable 13C and 15N isotope values and FA profiles of biota in the Pisquid River, Prince Edward Island, Canada. We sampled periphyton, benthic macroinvertebrates, and stream-resident Brook Trout (Salvelinus fontinalis Mitchell, 1814) at a downstream site encompassing Rainbow Smelt spawning grounds and an upstream site inaccessible to Rainbow Smelt. During the Rainbow Smelt migration at the downstream site, predatory caddisflies (Rhyacophilidae) and Brook Trout displayed a 3.1‰ and 1.3‰ increase in δ13C and δ15N, respectively, relative to isotope levels before the migration. Less consistent evidence of MDN assimilation was found in periphyton and nonpredatory macroinvertebrates (Heptageniidae, Elmidae). Increases in δ13C values for Rhyacophilidae and Brook Trout indicated direct consumption of tissue, most probably eggs based on limited stomach content analysis in Brook Trout. FA composition differed between Rainbow Smelt and Brook Trout sampled down- and upstream. Transfer of marine ω-3 FAs was evidenced by statistically similar amounts of eicosapentaenoic and docosahexaenoic acid between Rainbow Smelt and Brook Trout sampled on spawning grounds. We found connections between Rainbow Smelt-based MDNs and stream food webs and a nutritional benefit to Brook Trout. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
16. Predator switching strength controls stability in diamond-shaped food web models.
- Author
-
Archibald, Kevin M., Sosik, Heidi M., Moeller, Holly V., and Neubert, Michael G.
- Subjects
- *
FOOD chains , *PREDATION , *LIMIT cycles , *COMMUNITIES , *LOTKA-Volterra equations , *PREDATORY animals , *MARINE plankton - Abstract
In food web models that include more than one prey type for a single predator, it is common for the predator's functional response to include some form of switching—preferential consumption of more abundant prey types. Predator switching promotes coexistence among competing prey types and increases diversity in the prey community. Here, we show how the dynamics of a diamond-shaped food web model of a marine plankton community are sensitive to a parameter that sets the strength of predator switching. Stronger switching destabilizes the model's coexistence equilibrium and leads to the appearance of limit cycles. Stronger switching also increases the evenness of the asymptotic prey community and promotes synchrony in the dynamics of disparate prey types. Given the dependence of model behavior on the strength of predator switching, it is important that modelers carefully consider the parameterization of functional responses that include switching. • Predators that exhibit switching promote coexistence between prey types. • However, strong switching may destabilize this coexistence and produce limit cycles. • In communities with many prey, evenness increases with the strength of switching. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
17. The ecology, physiology, and diversity of aerobic anoxygenic phototrophs in Lake Winnipeg, Canada
- Author
-
Dr. Kumar, Ayush (Microbiology), Dr. Sparling, Richard (Microbiology), Dr. Piercey-Normore, Michele (Biology), Dr. Madigan, Michael (Distinguished Professor Emeritus, Southern Illinois University), Yurkov, Vladimir, Kuzyk, Steven Brady, Dr. Kumar, Ayush (Microbiology), Dr. Sparling, Richard (Microbiology), Dr. Piercey-Normore, Michele (Biology), Dr. Madigan, Michael (Distinguished Professor Emeritus, Southern Illinois University), Yurkov, Vladimir, and Kuzyk, Steven Brady
- Abstract
Aerobic anoxygenic phototrophs (AAP) are a group of photoheterotrophic bacteria that use sunlight as a supplemental energy source, allowing them to be found in many illuminated environments. Here, we investigated their presence in Lake Winnipeg, Manitoba, Canada with spatial and temporal considerations to define the niche that they fill, and understand the biogeochemical pathways influenced or controlled by AAP. In addition, we explored their diversity and expanded upon the range of photosynthetic arrangements known, by looking into a variety of newly purified pigmented isolates to assess unique characteristics, all of which allowed us to better understand the AAP group as a whole. We described seasonal trends of microbial communities in Lake Winnipeg, where up to 1.49% of the sequenced community and 19.1% of the total culturable copiotrophic heterotrophs were AAP at littoral zones during their peak spring season, and they directly followed sunlight availability. Isolated and purified strains were capable of several metal transformations, including metal(loid) oxide reduction and production of siderophores or metallophores. This widespread physiology, particularly among lake isolates, suggested a potential ecological importance for AAP involving a metal(loid) collecting niche. AAP with elongated cells were established as both associated to, and possibly preyed upon by filter feeding mollusks Dreissena polymorpha, which provided insights into how these bacteria interact with the foodweb. Many pigmented and phylogenetically diverse strains were discovered from across the lakes euphotic zones. Representatives of each different species were physiologically, morphologically and phylogenetically compared and described, showing members of specific taxonomic families all shared heritable traits including pigments. This confirmed evolutionary age of photosynthesis in AAP, and suggested recent horizontal gene transfer events did not occur. Furthermore, unusual aerobic violet
- Published
- 2022
18. Phototrophic Bacteria.
- Author
-
Blankenship, Robert, Blankenship, Robert, and Sattley, Matthew
- Subjects
Biology, life sciences ,Microbiology (non-medical) ,Research & information: general ,AAP ,Acaryochloris ,AerR photoreceptor ,Alphaproteobacteria ,Chloroflexus aurantiacus ,DNA binding ,Ectothiorhodospiraceae ,FNR ,Halorhodospira abdelmalekii ,Halorhodospira halochloris ,Halorhodospiraceae ,Heliobacteria ,Heliophilum fasciatum ,HiPIP ,Ignavibacteria ,Lake Winnipeg ,Moss Beach ,NDH ,NDH-1 ,Nostoc sp ,Photosystem II ,PpsR ortholog ,RNase ,RegA ,Rhodobacter ,Rhodocyclus ,Rhodovulum sulfidophilum ,Rhodovulum tesquicola ,Rhodovulum visakhapatnamense ,Synechococcus sp. PCC 7335 ,Synechocystis ,Yellowstone ,absorbance spectra ,aerobic ,aerobic anoxygenic phototrophic bacteria ,aerobic anoxygenic phototrophs ,alkaliphiles ,alternative complex III ,ancestral sequence reconstruction ,anoxygenic phototrophs ,bacterial community ,bacteriochlorophyll ,bacteriochlorophyll b ,bacteriochlorophyll g ,bacterioplankton ,carotenoid ,chelatase ,chlIDH ,chlorophototroph ,chlorophyll ,chlorophyll d ,chlorophyll f ,chlorosome ,chromatic acclimation ,class Chlorobia and the families Chlorobiaceae and Chloroherpetonaceae ,cobNST ,cobalamin ,comparative genome analysis ,comparative genomics ,conserved signature indels (CSIs) ,copper ion ,cryo-electron microscopy ,cyanobacteria ,cyanobacterial photoreceptors ,cyanophage ,cyclic GMP ,cyclic electron flow ,diazotroph ,disulfide bond ,electron transport ,energy metabolism ,evolution ,extremophile ,far-red light photoacclimation ,far-red photosynthesis ,ferredoxin-NADP reductase ,food web dynamics ,frameshifting ,gene expression ,gene regulation ,gene transfer ,genome sequence ,genomic phylogeny ,genomics ,gracilis ,halophiles ,heliobacteria ,high light ,horizontal gene transfer ,hot spring ,hydrogen ,label-free quantitative proteomics ,light regulation ,light-harvesting ,light-harvesting 1 reaction center ,linker proteins ,microbial ecology of lakes ,molecular signatures ,near infrared ,new family and genus ,nitrogen fixation ,oxygenic photosynthesis ,persulfide ,photoheterotrophic growth ,photosynthesis ,photosynthesis gene regulators ,photosynthetic pigments ,photosynthetic reaction center ,photosystem I ,photosystem II ,phototrophic bacteria ,phototrophic extracellular electron uptake ,phycobiliproteins ,phycobilisome ,phylogenetic comparison ,phylogenomic and comparative genomic analyses ,picoplankton ,plasmid ,promoters ,proteomic analysis ,proton motive force ,purple nonsulfur bacteria ,purple phototrophic bacteria ,purple sulfur bacteria ,purpureus ,redox signaling ,reduction-oxidation ,reporters ,respiration ,salt- and pH-dependence ,scytonemin ,shark bay ,stromatolite ,substance metabolism ,taxonomy ,tenuis ,thermal stability ,thermophile ,thylakoid ,transcriptional regulation ,transcriptomics ,two-component system ,ultraviolet radiation ,uncultured species/strains related to Chlorobia/Ignavibacteria ,vitamin B12 ,whole genome sequencing ,xanthorhodopsin ,zeta-carotene isomerase (Z-ISO) - Abstract
Summary: Microorganisms is pleased to publish this book, which reprints papers that appeared in a Special Issue on "Phototrophic Bacteria", with Guest Editors Robert Blankenship and Matthew Sattley. This Special Issue included research on all types of phototrophic bacteria, including both anoxygenic and oxygenic forms. Research on these bacterial organisms has greatly advanced our understanding of the basic principles that underlie the energy storage that takes place in all types of photosynthetic organisms, including both bacterial and eukaryotic forms. Topics of interest include: microbial physiology, microbial ecology, microbial genetics, evolutionary microbiology, systems microbiology, agricultural microbiology, microbial biotechnology, and environmental microbiology, as all are related to phototrophic bacteria.
19. Effects of spawning Atlantic salmon (Salmo salar) on total lipid content and fatty acid composition of river food webs
- Author
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Kurt M. Samways, Tammy J. Blair, Michelle A. Charest, and Richard A. Cunjak
- Subjects
anadromous fish ,Atlantic salmon ,biofilm ,Eastern Canada ,fatty acids ,food web dynamics ,Ecology ,QH540-549.5 - Abstract
Abstract Returning Atlantic salmon subsidize rivers with marine‐derived nutrients (MDNs), potentially altering food web dynamics, shifting to reliance on marine‐derived resources. Stream channels designed to simulate natural river systems, one with MDNs from spawning Atlantic salmon (Salmo salar) and one without marine‐nutrient subsidies (control), were used to determine whether fatty acids (FAs) delivered to rivers and streams by spawning Atlantic salmon are incorporated by freshwater biota. Changes in FA profiles between stream channels with and without MDN inputs for biofilm, macroinvertebrates, and Atlantic salmon parr were used to characterize temporal dynamics of MDN incorporation during pre‐spawning, spawning, and post‐spawning periods. There were no differences between control and treatment stream channels prior to the addition of Atlantic salmon. Spawning Atlantic salmon had a positive effect on total lipid content in all trophic levels (biofilm, 4.33%; macroinvertebrates, 7.54%; salmon parr, 2.59%), relative to controls. Fatty acid profiles between the MDN treatment and control stream channels were similar for each biotic group prior to the introduction of adult Atlantic salmon; however, following adult salmon introductions, the FA profiles of the biofilm, invertebrates, and salmon parr differed by as much as 36.7%, 30.3%, and 22.9%, respectively, between the MDN treatment stream channels and the controls. Fatty acid profiles of the invertebrates and salmon parr from the MDN treatment stream channels tracked the FA profile of the salmon eggs. Proportions of docosahexaenoic acid and eicosapentaenoic acid varied with diet in a predictable manner related to dietary FA proportions. These responses demonstrate a change in the food web structure resulting from the establishment of this new, marine‐based, basal resource. The positive effects of MDNs increasing freshwater productivity are complimented by marine‐based lipids that represent surplus energy and an increase in the quality of resources, thereby contributing to the diversity and health of freshwater ecosystems.
- Published
- 2017
- Full Text
- View/download PDF
20. Biogeochemical Equation of State for the Sea-Air Interface
- Author
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Scott Elliott, Zachary Menzo, Amadini Jayasinghe, Heather C. Allen, Oluwaseun Ogunro, Georgina Gibson, Forrest Hoffman, and Oliver Wingenter
- Subjects
marine surface tension and pressure ,surfactant macromolecules ,proxy compounds ,food web dynamics ,interfacial equation of state ,upper ocean eddies ,capillaries ,bubbles ,Prandtl stress ,ecogeography ,momentum-heat-gas-salt exchange ,global monolayer ,Meteorology. Climatology ,QC851-999 - Abstract
We have recently argued that marine interfacial surface tension must have a distinctive biogeography because it is mediated by fresh surfactant macromolecules released locally through the food web. Here we begin the process of quantification for associated climate flux implications. A low dimensionality (planar) equation of state is invoked at the global scale as our main analysis tool. For the reader’s convenience, fundamental surfactant physical chemistry principles are reviewed first, as they pertain to tangential forces that may alter oceanic eddy, ripple, and bubble fields. A model Prandtl (neutral) wind stress regime is defined for demonstration purposes. It is given the usual dependence on roughness, but then in turn on the tension reduction quantity known as surface pressure. This captures the main net influences of biology and detrital organics on global microlayer physics. Based on well-established surrogate species, tangent pressures are related to distributed ecodynamics as reflected by the current marine systems science knowledge base. Reductions to momentum and related heat-vapor exchange plus gas and salt transfer are estimated and placed on a coarse biogeographic grid. High primary production situations appear to strongly control all types of transfer, whether seasonally or regionally. Classic chemical oceanographic data on boundary state composition and behaviors are well reproduced, and there is a high degree of consistency with conventional micrometeorological wisdom. But although our initial best guesses are quite revealing, coordinated laboratory and field experiments will be required to confirm the broad hypotheses even partially. We note that if the concepts have large scale validity, they are super-Gaian. Biological control over key planetary climate-transfer modes may be accomplished through just a single rapidly renewed organic monolayer.
- Published
- 2019
- Full Text
- View/download PDF
21. Abiotic and biotic factors modulate carrion fate and vertebrate scavenging communities.
- Author
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Turner, Kelsey L., Abernethy, Erin F., Conner, L. Mike, Rhodes, Olin E., and Beasley, James C.
- Subjects
- *
ANIMAL carcasses , *BIOTIC communities , *FOOD chains , *SCAVENGER receptors (Biochemistry) , *WILD boar - Abstract
Carrion is a valuable nutrient resource used by a diversity of vertebrates across the globe. However, vertebrate scavenging ecology remains an understudied area of science, especially in regards to how biotic and abiotic factors influence scavenging community composition. Here we elucidate how fundamental biotic and abiotic factors interact to modulate the efficiency and composition of vertebrate scavengers by investigating scavenging dynamics across a large gradient in carcass sizes and habitat types representative of many temperate ecosystems, as well as between two seasons reflecting differences in invertebrate activity. We found carcass size and season influenced carcass fate and persistence, as well as the richness and composition of vertebrate scavenger communities utilizing carrion resources. Species richness, which increased as carcass size increased and was higher during the cool season, had a significant effect on carcass persistence. In addition, habitat type influenced carcass detection times by vertebrates, and we observed relatively distinct scavenging communities associated with carcasses of differing sizes. This research highlights a pervasive limitation to the interpretation of results of previous studies as research failing to incorporate carcass size and habitat type could result in the over or underrepresentation of vertebrate scavengers in food web dynamics. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
22. Conceptualizing ecosystem tipping points within a physiological framework.
- Author
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Harley, Christopher D. G., Connell, Sean D., Doubleday, Zoë A., Kelaher, Brendan, Russell, Bayden D., Sarà, Gianluca, and Helmuth, Brian
- Subjects
- *
ECOSYSTEMS , *FOOD chains , *PHYSIOLOGICAL stress , *BIOTIC communities , *PHYSICAL environment - Abstract
Connecting the nonlinear and often counterintuitive physiological effects of multiple environmental drivers to the emergent impacts on ecosystems is a fundamental challenge. Unfortunately, the disconnect between the way 'stressors' (e.g., warming) is considered in organismal (physiological) and ecological (community) contexts continues to hamper progress. Environmental drivers typically elicit biphasic physiological responses, where performance declines at levels above and below some optimum. It is also well understood that species exhibit highly variable response surfaces to these changes so that the optimum level of any environmental driver can vary among interacting species. Thus, species interactions are unlikely to go unaltered under environmental change. However, while these nonlinear, species-specific physiological relationships between environment and performance appear to be general, rarely are they incorporated into predictions of ecological tipping points. Instead, most ecosystem-level studies focus on varying levels of 'stress' and frequently assume that any deviation from 'normal' environmental conditions has similar effects, albeit with different magnitudes, on all of the species within a community. We consider a framework that realigns the positive and negative physiological effects of changes in climatic and nonclimatic drivers with indirect ecological responses. Using a series of simple models based on direct physiological responses to temperature and ocean pCO2, we explore how variation in environment-performance relationships among primary producers and consumers translates into community-level effects via trophic interactions. These models show that even in the absence of direct mortality, mismatched responses resulting from often subtle changes in the physical environment can lead to substantial ecosystem-level change. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
23. Effects of spawning Atlantic salmon (Salmo salar) on total lipid content and fatty acid composition of river food webs.
- Author
-
Samways, Kurt M., Blair, Tammy J., Charest, Michelle A., and Cunjak, Richard A.
- Subjects
ATLANTIC salmon ,SPAWNING ,FISH lipids ,FATTY acids ,MARINE food chain - Abstract
Returning Atlantic salmon subsidize rivers with marine-derived nutrients (MDNs), potentially altering food web dynamics, shifting to reliance on marine-derived resources. Stream channels designed to simulate natural river systems, one with MDNs from spawning Atlantic salmon (Salmo salar) and one without marine-nutrient subsidies (control), were used to determine whether fatty acids (FAs) delivered to rivers and streams by spawning Atlantic salmon are incorporated by freshwater biota. Changes in FA profiles between stream channels with and without MDN inputs for biofilm, macroinvertebrates and Atlantic salmon parr were used to characterize temporal dynamics of MDN incorporation during pre-spawning, spawning and post-spawning periods. There were no differences between control and treatment stream channels prior to the addition of Atlantic salmon. Spawning Atlantic salmon had a positive effect on total lipid content in all trophic levels (biofilm, 4.33%; macroinvertebrates, 7.54%; salmon parr, 2.59%), relative to controls. Fatty acid profiles between the MDN treatment and control stream channels were similar for each biotic group prior to the introduction of adult Atlantic salmon; however, following adult salmon introductions, the FA profiles of the biofilm, invertebrates and salmon parr differed by as much as 36.7%, 30.3%, and 22.9%, respectively, between the MDN treatment stream channels and the controls. Fatty acid profiles of the invertebrates and salmon parr from the MDN treatment stream channels tracked the FA profile of the salmon eggs. Proportions of docosahexaenoic acid and eicosapentaenoic acid varied with diet in a predictable manner related to dietary FA proportions. These responses demonstrate a change in the food web structure resulting from the establishment of this new, marine-based, basal resource. The positive effects of MDNs increasing freshwater productivity are complimented by marine-based lipids that represent surplus energy and an increase in the quality of resources, thereby contributing to the diversity and health of freshwater ecosystems. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
24. Different life cycle strategies of the dinoflagellates Fragilidium duplocampanaeforme and its prey Dinophysis acuminata may explain their different susceptibilities to the infection by the parasite Parvilucifera infectans.
- Author
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Lee, Bora and Park, Myung Gil
- Subjects
- *
DINOFLAGELLATES , *ZOOSPORES , *DEFENSE reaction (Physiology) , *FOOD chains , *PARASITISM - Abstract
Some marine dinoflagellates form ecdysal cyst (=temporary cysts) as part of their life cycle or under unfavorable growth conditions. Whether the dinoflagellates form ecdysal cysts or not may influence susceptibility to parasitism. In this study, parasite prevalence relative to inoculum size of the parasitoid Parvilucifera infectans zoospores for two dinoflagellate hosts (i.e., Fragilidium duplocampanaeforme and Dinophysis acuminata) , which have different life cycle strategies, was examined. Further, susceptibility of cysts to parasitism, encystment signal, duration of encystments, and effects of induced encystment on diel periodicity, using ecdysal cyst-forming F. duplocampanaeforme were explored. The percent hosts infected by P. infectans plotted as a function of inoculum size showed a sharp increase to a maximum in D. acuminata , but a gradual linear rise in F. duplocampanaeforme : while the parasite prevalence in D. acuminata increased to a maximum of 78.8 (±2.4%) by a zoospore:host ratio of 20:1, it in F. duplocampanaeforme only reached 8.9 (±0.3%), even at a zoospore:host ratio of 120:1. In F. duplocampanaeforme , infections were observed only in the vegetative cells and not observed in ecdysal cysts. When exposed to live, frozen, and sonicated zoospores and zoospore filtrate, F. duplocampanaeforme formed ecdysal cysts only when exposed to live zoospores, suggesting that temporary cyst formation in the dinoflagellate resulted from direct contact with zoospores. When the Parvilucifera zoospores attacked and struggled to penetrate F. duplocampanaeforme through its flagellar pore, the Fragilidium cell shed all thecal plates, forming a ‘thecal cloud layer’, in which the zoospores were caught and immobilized and thus could not penetrate anymore. The duration (35 ± 1.8 h) of ecdysal cysts induced with addition of zoospores was significantly longer than that (15 ± 0.8 h) of normally formed cysts (i.e., without addition of zoospores), thereby resulting in delayed growth as well as influencing the pattern of diel periodicity. The results from this study suggest that in addition to the classical predator-prey interaction and allelopathic interaction, parasitism and its accompanying defense can make the food web dynamics much more complicated than previously thought. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
25. Global data set for nitrogen and carbon stable isotopes of tunas
- Author
-
Bodin, Nathalie, Pethybridge, Heidi, Duffy, Leanne M., Lorrain, Anne, Allain, Valerie, Logan, John M., Ménard, Frederic, Graham, Brittany, Choy, C. Anela, Somes, Christopher J., Olson, Robert J., Young, Jock W., Bodin, Nathalie, Pethybridge, Heidi, Duffy, Leanne M., Lorrain, Anne, Allain, Valerie, Logan, John M., Ménard, Frederic, Graham, Brittany, Choy, C. Anela, Somes, Christopher J., Olson, Robert J., and Young, Jock W.
- Abstract
Nitrogen and carbon stable isotope data sets are commonly used to assess complex population to ecosystem responses to natural or anthropogenic changes at regional to global spatial scales, and monthly to decadal timescales. Measured in the tissues of consumers, nitrogen isotopes (δ15N) are primarily used to estimate trophic position while carbon isotopes (δ13C) describe habitat associations and feeding pathways. Models of both δ15N and δ13C values and their associated variance can be used to estimate likely dietary contributions and niche width and provide inferences about consumer movement and migration. Stable isotope data have added utility when used in combination with other empirical data sets (e.g., stomach content, movement tracking, bioregionalization, contaminant, or fisheries data) and are increasingly relied upon in food web and ecosystem models. While numerous regional studies publish tables of mean δ15N and δ13C values, limited individual records have been made available for wider use. Such a deficiency has impeded full utility of the data which otherwise would facilitate identification of macroscale patterns. The data provided here consist of 4,498 records of individuals of three tuna species, Thunnus alalunga, T. obesus, and T. albacares sampled from all major ocean basins from 2000 to 2015. For each individual tuna we provide a record of the following: species name, sampling date, sampling location, tuna length, muscle bulk and baseline corrected δ15N values, and muscle bulk and, where available, lipid corrected δ13C values. We provide these individual records to support comparative studies and more robust modelling projects seeking to improve understanding of complex marine ecosystem dynamics and their responses to a changing environment. There are no copyright restrictions for research and/or teaching purposes. Users are requested to acknowledge their use of the data in publications, research proposals, websites and other outlets following the cita
- Published
- 2021
- Full Text
- View/download PDF
26. Editorial : Roles and mechanisms of parasitism in aquatic microbial communities
- Author
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Télesphore eSime-Ngando, Kevin D. Lafferty, and David G. Biron
- Subjects
Ecology ,microbial communities ,Food Web Dynamics ,Parasitism ,Hyperparasitism ,Microbiology ,QR1-502 - Published
- 2015
- Full Text
- View/download PDF
27. Using Daphnia physiology to drive food web dynamics: A theoretical revisit of Lotka-Volterra models.
- Author
-
Perhar, Gurbir, Kelly, Noreen E., Ni, Felicity J., Simpson, Myrna J., Simpson, Andre J., and Arhonditsis, George B.
- Subjects
DAPHNIA ,FOOD chains ,LOTKA-Volterra equations ,BIOLOGICAL mathematical modeling ,PHYTOPLANKTON ,PHYSIOLOGY - Abstract
The Lotka–Volterra model is the most commonly used framework to describe the dynamics of ecological systems in which two species interact, one as a predator and the other as prey. Theoretical ecologists have since built on variants of these equations, frequently applying them to model the dynamics of algal-herbivore interactions in aquatic systems. In this study, we augment a Lotka–Volterra system by introducing a bioenergetically-explicit, ecophysiological model to examine how variations in resource allocation affect zooplankton growth and subsequently phytoplankton dynamics. Ingested material within a zooplankter's gut is separated into distinct internal congener pools that are used to support physiological processes occurring in a hierarchical direction: neurological functions, energetics, osmoregulatory maintenance, waste management, and finally growth. Consistent with the predictions of the “stoichiometric knife edge” theory, our analysis suggests that a balanced algal congener composition is required to optimize zooplankton internal congener saturations, resulting in a maximal allocation of energy to growth. In examining the advantages rendered by different strategies of minimum and optimum somatic quotas when experiencing phosphorus-enrichment conditions, we show that herbivores with narrow homeostatic bounds and animals with low minimum quotas (or depletion specialists) achieve optimal performance first. Our analysis also predicts patterns of multiple stable equilibria in which the same environmental conditions can be characterized by dramatically different prey-to-predator ratios. Importantly, abrupt shifts from one state to another can be induced not only by short-term variations in food abundance but also by variations in the nutritional quality of the prey. Our predictions have profound implications for connecting microscopic processes with macroscopic patterns and offer new insights into the multitude of factors that modulate food web dynamics. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
28. Compensatory dynamics stabilize aggregate community properties in response to multiple types of perturbations.
- Author
-
BROWN, BRYAN L., DOWNING, AMY L., and LEIBOLD, MATHEW A.
- Subjects
- *
ZOOPLANKTON , *ECOLOGICAL disturbances , *ECOPHYSIOLOGY , *FOOD chains , *META-analysis - Abstract
Compensatory dynamics are an important suite of mechanisms that can stabilize community and ecosystem attributes in systems subject to environmental fluctuations. However, few experimental investigations of compensatory dynamics have addressed these mechanisms in systems of real-world complexity, and existing evidence relies heavily on correlative analyses, retrospective examination, and experiments in simple systems. We investigated the potential for compensatory dynamics to stabilize plankton communities in plankton mesocosm systems of real-world complexity. We employed four types of perturbations including two types of nutrient pulses, shading, and acidification. To quantify how communities responded to these perturbations, we used a measure of community-wide synchrony combined with spectral analysis that allowed us to assess timescale-specific community dynamics, for example, whether dynamics were synchronous at some timescales but compensatory at others. The 150-d experiment produced 32-point time series of all zooplankton taxa in the mesocosms. We then used those time series to evaluate total zooplankton biomass as an aggregate property and to evaluate community dynamics. For three of our four perturbation types, total zooplankton biomass was significantly less variable in systems with environmental variation than in constant environments. For the same three perturbation types, community-wide synchrony was much lower in fluctuating environments than in the constant environment, particularly at longer timescales (periods ≈ 60 d). Additionally, there were strong negative correlations between population temporal variances and the level of community-wide synchrony. Taken together, these results strongly imply that compensatory interactions between species stabilized total biomass in response to perturbations. Diversity did not differ significantly across either treatments or perturbation types, thus ruling out several classes of mechanisms driven by changes in diversity. We also used several pieces of secondary evidence to evaluate the particular mechanism behind compensatory responses since a wide variety of mechanisms are hypothesized to produce compensatory dynamics. We concluded that fluctuation dependent endogenous cycles that occur as a consequence of consumer-resource interactions in competitive communities were the most likely explanation for the compensatory dynamics observed in our experiment. As with our previous work, scale-dependent dynamics were also a key to understanding compensatory dynamics in these experimental communities. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
29. The effects of planktivorous fishes on the plankton community in a eutrophic lake
- Author
-
Miura, T., Dumont, H. J., editor, Gulati, Ramesh D., editor, Lammens, Eddy H. R. R., editor, Meijer, Marie-Louise, editor, and van Donk, Ellen, editor
- Published
- 1990
- Full Text
- View/download PDF
30. Global data set for nitrogen and carbon stable isotopes of tunas
- Author
-
Nathalie Bodin, Heidi Pethybridge, Anne Lorrain, C. Anela Choy, Jock W. Young, Robert J. Olson, Frédéric Ménard, John M. Logan, Leanne M. Duffy, Valerie Allain, Brittany S. Graham, Christopher J. Somes, MARine Biodiversity Exploitation and Conservation (UMR MARBEC), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut méditerranéen d'océanologie (MIO), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut de Recherche pour le Développement (IRD), and Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
0106 biological sciences ,Population ,baseline isotopic variability ,010603 evolutionary biology ,01 natural sciences ,trophic position ,pelagic ecosystem ,Ecosystem ,Marine ecosystem ,14. Life underwater ,education ,ComputingMilieux_MISCELLANEOUS ,Ecology, Evolution, Behavior and Systematics ,Trophic level ,[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere ,education.field_of_study ,Stable isotope ratio ,Ecology ,scombrids ,010604 marine biology & hydrobiology ,Sampling (statistics) ,Food web ,marine top predators ,Environmental science ,Global Ocean ,food web dynamics ,Physical geography ,Tuna - Abstract
Nitrogen and carbon stable isotope data sets are commonly used to assess complex population to ecosystem responses to natural or anthropogenic changes at regional to global spatial scales, and monthly to decadal timescales. Measured in the tissues of consumers, nitrogen isotopes (delta N-15) are primarily used to estimate trophic position while carbon isotopes (delta C-13) describe habitat associations and feeding pathways. Models of both delta N-15 and delta C-13 values and their associated variance can be used to estimate likely dietary contributions and niche width and provide inferences about consumer movement and migration. Stable isotope data have added utility when used in combination with other empirical data sets (e.g., stomach content, movement tracking, bioregionalization, contaminant, or fisheries data) and are increasingly relied upon in food web and ecosystem models. While numerous regional studies publish tables of mean delta N-15 and delta C-13 values, limited individual records have been made available for wider use. Such a deficiency has impeded full utility of the data, which otherwise would facilitate identification of macroscale patterns. The data provided here consist of 4,498 records of individuals of three tuna species, Thunnus alalunga, T. obesus, and T. albacares sampled from all major ocean basins from 2000 to 2015. For each individual tuna, we provide a record of the following: species name, sampling date, sampling location, tuna length, muscle bulk and baseline corrected delta N-15 values, and muscle bulk and, where available, lipid corrected delta C-13 values. We provide these individual records to support comparative studies and more robust modeling projects seeking to improve understanding of complex marine ecosystem dynamics and their responses to a changing environment. There are no copyright restrictions for research and/or teaching purposes. Users are requested to acknowledge their use of the data in publications, research proposals, websites, and other outlets following the citation instructions in Class III, Section B.
- Published
- 2021
- Full Text
- View/download PDF
31. Global data set for nitrogen and carbon stable isotopes of tunas [Data paper]
- Author
-
Bodin, Nathalie, Pethybridge, H., Duffy, L. M., Lorrain, Anne, Allain, V., Logan, J. M., Ménard, Frédéric, Graham, B., Choy, C. A., Somes, C. J., Olson, R. J., and Young, J. W.
- Subjects
marine top predators ,pelagic ecosystem ,scombrids ,Global Ocean ,food web dynamics ,baseline isotopic variability ,trophic position - Abstract
Nitrogen and carbon stable isotope data sets are commonly used to assess complex population to ecosystem responses to natural or anthropogenic changes at regional to global spatial scales, and monthly to decadal timescales. Measured in the tissues of consumers, nitrogen isotopes (delta N-15) are primarily used to estimate trophic position while carbon isotopes (delta C-13) describe habitat associations and feeding pathways. Models of both delta N-15 and delta C-13 values and their associated variance can be used to estimate likely dietary contributions and niche width and provide inferences about consumer movement and migration. Stable isotope data have added utility when used in combination with other empirical data sets (e.g., stomach content, movement tracking, bioregionalization, contaminant, or fisheries data) and are increasingly relied upon in food web and ecosystem models. While numerous regional studies publish tables of mean delta N-15 and delta C-13 values, limited individual records have been made available for wider use. Such a deficiency has impeded full utility of the data, which otherwise would facilitate identification of macroscale patterns. The data provided here consist of 4,498 records of individuals of three tuna species, Thunnus alalunga, T. obesus, and T. albacares sampled from all major ocean basins from 2000 to 2015. For each individual tuna, we provide a record of the following: species name, sampling date, sampling location, tuna length, muscle bulk and baseline corrected delta N-15 values, and muscle bulk and, where available, lipid corrected delta C-13 values. We provide these individual records to support comparative studies and more robust modeling projects seeking to improve understanding of complex marine ecosystem dynamics and their responses to a changing environment. There are no copyright restrictions for research and/or teaching purposes. Users are requested to acknowledge their use of the data in publications, research proposals, websites, and other outlets following the citation instructions in Class III, Section B.
- Published
- 2021
32. Interactions among mutualism, competition, and predation foster species coexistence in diverse communities.
- Author
-
Bachelot, Benedicte, Uriarte, María, and McGuire, Krista
- Subjects
PREDATORY animals ,DENSITY dependence (Ecology) ,ANIMAL population density ,FOOD chains ,BIOLOGICAL productivity ,ANIMAL feeding behavior - Abstract
In natural systems, organisms are simultaneously engaged in mutualistic, competitive, and predatory interactions. Theory predicts that species persistence and community stability are feasible when the beneficial effects of mutualisms are balanced by density-dependent negative feedbacks. Enemy-mediated negative feedbacks can foster plant species coexistence in diverse communities, but empirical evidence remains mixed. Disparity between theoretical expectations and empirical results may arise from the effects of mutualistic mycorrhizal fungi. Here, we build a multiprey species/predator model combined with a bidirectional resource exchange system, which simulates mutualistic interactions between plants and fungi. To reach population persistence, (1) the per capita rate of increase of all plant population must exceed the sum of the negative per capita effects of predation, interspecific competition, and costs of mycorrhizal association, and (2) the per capita numerical response of enemies to mycorrhizal plants must exceed the magnitude of the per capita enemy rate of mortality. These conditions reflect the balance between regulation and facilitation in the system. Interactions between plant natural enemies and mycorrhizal fungi lead to shifts in the strength and direction of net mycorrhizal effects on plants over time, with common plant species deriving greater benefits from mycorrhizal associations than rare plant species. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
33. Environmental bacteriophages: viruses of microbes in aquatic ecosystems.
- Author
-
Sime-Ngando, Télesphore
- Subjects
LYSOGENY ,BACTERIAL genetics ,GENETIC transformation ,FOOD chains ,VIRUSES ,BIODIVERSITY research ,BACTERIOPHAGES - Abstract
Since the discovery 2-3 decades ago that viruses of microbes are abundant in marine ecosystems, viral ecology has grown increasingly to reach the status of a full scientific discipline in environmental sciences. A dedicated ISVM society, the International Society for Viruses of Microorganisms, (http://www.isvm.org/) was recently launched. Increasing studies in viral ecology are sources of novel knowledge related to the biodiversity of living things, the functioning of ecosystems, and the evolution of the cellular world. This is because viruses are perhaps the most diverse, abundant, and ubiquitous biological entities in the biosphere, although local environmental conditions enrich for certain viral types through selective pressure. They exhibit various lifestyles that intimately depend on the deep-cellular mechanisms, and are ultimately replicated by members of all three domains of cellular life (Bacteria, Eukarya, Archaea), as well as by giant viruses of some eukaryotic cells.This establishes viral parasites as microbial killers but also as cell partners or metabolic manipulators in microbial ecology. The present chapter sought to review the literature on the diversity and functional roles of viruses of microbes in environmental microbiology, focusing primarily on prokaryotic viruses (i.e., phages) in aquatic ecosystems, which form the bulk of our knowledge in modern environmental viral ecology. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
34. Interpreting variation in fish-based food web indicators: the importance of “bottom-up limitation” and “top-down control” processes.
- Author
-
Reilly, T., Fraser, H. M., Fryer, R. J., Clarke, J., and Greenstreet, S. P. R.
- Subjects
- *
AMMODYTES , *FOOD chains , *TOP predators , *FISH ecology , *FISHERY management - Abstract
Reilly, T., Fraser, H. M., Fryer, R. J., Clarke, J., and Greenstreet, S. P. R. 2014. Interpreting variation in fish-based food web indicators: the importance of “bottom-up limitation” and “top-down control” processes. – ICES Journal of Marine Science, 71: 406–416.Proposed indicators for the Marine Strategy Framework Directive (MSFD) food webs Descriptor focus on structural elements of food webs, and in particular on the abundance and productivity of top predators. However, the inferences that can be drawn from such indicators depend on whether or not the predators are “bottom-up limited” by the availability of their prey. Many seabird populations appear to be “bottom-up limited” so that variation in their reproductive success and/or abundance reflects changes in lower trophic levels. Here we find that gadoid fish predators off the Firth of Forth, southeast Scotland, do not appear to be “bottom-up limited” by the biomass of their main prey, 0-group sandeels; gadoid biomass and feeding performance was independent of sandeel biomass. Variability in food web indicators based on these gadoid predators seems to impart little insight into underlying processes occurring at lower trophic levels in the local food web. The implications of this in terms of how the currently proposed MSFD food web indicators should be used and interpreted are considered, and the ramifications in terms of setting targets representing good environmental status for both fish and seabird communities are discussed. [ABSTRACT FROM PUBLISHER]
- Published
- 2014
- Full Text
- View/download PDF
35. Responses of algae, bacteria, Daphnia and natural parasite fauna of Daphnia to nutrient enrichment in mesocosms.
- Author
-
Aalto, Sanni, Kaski, Outi, Salonen, Kalevi, and Pulkkinen, Katja
- Subjects
- *
DAPHNIA , *STOICHIOMETRY , *FOOD chains , *GLOBAL environmental change , *SESTON , *PHYSIOLOGY - Abstract
Understanding responses of parasites to changes in nutrient regimes is necessary for prediction of their role in aquatic ecosystems under global change in nutrient loading. We studied the response of the natural parasite fauna of Daphnia longispina to nutrient enrichment in mesocosms in a small humic lake. We measured the concentrations of inorganic phosphorus and nitrogen in the water, total nutrients in the seston, algal and bacterial biomass, Daphnia population dynamics, Daphnia stoichiometry, Daphnia stable isotope values and the presence and abundance of parasites in treated mesocosms as compared to three control ones. Incorporation of the nutrient enrichment in the food web was seen as increased nutrient concentrations in the epilimnion and as a decrease in carbon:nutrient ratios and δN values in Daphnia. Nutrient enrichment did not significantly influence algal, bacterial or Daphnia biomass. One of the four parasite species observed, unidentified small gut parasite, had a higher prevalence (percentage of Daphnia infected) in treated mesocosms, but its intensity (number of parasites per infected host) remained the same among treatments. Our results suggest that the effect of nutrient enrichment on host-parasite dynamics is dependent on complex interactions within food webs and on the epidemiological traits of parasites. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
36. Life in the slow lane: field metabolic rate and prey consumption rate of the Greenland shark (Somniosus microcephalus) modelled using archival biologgers.
- Author
-
Ste-Marie E, Watanabe YY, Semmens JM, Marcoux M, and Hussey NE
- Subjects
- Animals, Arctic Regions, Dogfish, Fisheries, Food Chain, Greenland, Mammals, Sharks metabolism
- Abstract
Field metabolic rate (FMR) is a holistic measure of metabolism representing the routine energy utilization of a species living within a specific ecological context, thus providing insight into its ecology, fitness and resilience to environmental stressors. For animals that cannot be easily observed in the wild, FMR can also be used in concert with dietary data to quantitatively assess their role as consumers, improving understanding of the trophic linkages that structure food webs and allowing for informed management decisions. Here, we modelled the FMR of Greenland sharks (Somniosus microcephalus) equipped with biologger packages or pop-up archival satellite tags (PSATs) in two coastal inlets of Baffin Island (Nunavut) using metabolic scaling relationships for mass, temperature and activity. We estimated that Greenland sharks had an overall mean (±s.d.) FMR of 21.67±2.30 mg O2 h-1 kg-0.84 (n=30; 1-4 day accelerometer package deployments) while residing inside these cold-water fjord systems in the late summer, and 25.48±0.47 mg O2 h-1 kg-0.84 (n=6; PSATs) over an entire year. When considering prey consumption rate, an average shark in these systems (224 kg) requires a maintenance ration of 61-193 g of fish or marine mammal prey daily. As Greenland sharks are a lethargic polar species, these low FMR estimates, and corresponding prey consumption estimates, suggest they require very little energy to sustain themselves under natural conditions. These data provide the first characterization of the energetics and consumer role of this vulnerable and understudied species in the wild, which is essential given growing pressures from climate change and expanding commercial fisheries in the Arctic., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2022. Published by The Company of Biologists Ltd.)
- Published
- 2022
- Full Text
- View/download PDF
37. Feeding hotspots for four northwest Atlantic groundfish species.
- Author
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Methratta, Elizabeth T. and Link, Jason S.
- Subjects
- *
GROUNDFISHES , *PREDATION , *WINTER flounder , *FISHERY management , *PREY availability - Abstract
Methratta, E.T., and Link, J.S. 2012. Feeding hotspots for four northwest Atlantic groundfish species. — ICES Journal of Marine Science, 69: 1710–1721.We used predator distribution and stomach content data to estimate the annual per capita rate of consumption for four representative predator species from the northwestern Atlantic Ocean, and considered how consumption is influenced by depth, bottom salinity, sediment grain size, location variables, and species-specific diet components. We found that geographic variables and species-specific prey resources were significantly associated with consumption rates, a pattern consistent with predator-prey theory. Prey categories comprised of fish were particularly important for a more mobile predator (silver hake Merluccius bilinearis), whereas benthic invertebrate prey were consistently important for a more sedentary predator (little skate Raja erinacea). Hotspots in consumption rates that overlap with particular prey resources were highlighted by the significance of location variables (longitude) for winter flounder Pseudopleuronectes americanus, silver hake, little skate, and sea raven Hemitripterus americanus. Depth was an important explanatory factor for consumption by little skate, but the explanatory value of abiotic habitat factors was low for the other three species. Greater emphasis on species-specific food habits, migratory patterns, and ecological interactions at the synoptic scales relevant to fisheries is needed for fisheries management. [ABSTRACT FROM PUBLISHER]
- Published
- 2012
- Full Text
- View/download PDF
38. Thiamin (vitamin B1) in the aquatic food web
- Author
-
Fridolfsson, Emil and Fridolfsson, Emil
- Abstract
Thiamin (vitamin B1) is required for several life-sustaining processes in most organisms and cells, e.g. in the conversion of food to energy. It also serves as an antioxidant and is important for proper nerve signaling. Thiamin is produced predominantly by bacteria and phytoplankton in the aquatic food web. Not all bacteria and phytoplankton, nor any organisms in higher trophic levels can produce thiamin; instead, they rely on a continuous external supply and uptake of this essential compound. Thiamin deficiencies occur episodically in a wide range of taxa, especially in higher trophic levels. In the Baltic Sea, thiamin deficiencies has been most pronounced in salmon (Salmo salar) and recently deficiencies are also reported for other fish species and birds. This thesis focuses on thiamin dynamics in lower trophic levels, covering primary producers as well as primary consumers, as this topic has not received much attention previously. Thiamin content of common phytoplankton and zooplankton species and the transfer between them was investigated in experiments and field studies. The relationship between thiamin deficiency and underlying environmental factors was also investigated using monitoring data. Thiamin content differed among phytoplankton classes, species and even strains. Filamentous Cyanophyceae had considerably higher thiamin content than other classes. However, thiamin transfer to copepods was lower, probably associated with difficulties ingesting the filaments. Moreover, thiamin content in seston varied seasonally, being highest during summer when both Prymnesiophyceae and filamentous Cyanophyceae were more abundant. Thiamin content in the two size fractions correlated strongly and was always higher in the smaller size fraction, illustrating the importance of picoplankton and bacteria in the food web. Also, seston thiamin content was higher in the Baltic Proper than in the Skagerrak. Copepods differed in thiamin content among genera, as well as between loc, Tiamin (vitamin B1) är nödvändigt för flera livsuppehållande processer i cellerna hos det stora flertalet organismer, t.ex. vid omvandling av näring till energi. Vitaminet fungerar också som en antioxidant och är viktigt för korrekt nervfunktion. I den akvatiska födoväven produceras tiamin i första hand av bakterier och växtplankton. Dock inte av alla bakterier och växtplankton, utan dem, liksom organismer från högre trofiska nivåer, måste förlita sig på kontinuerlig tillgång samt upptag av detta livsviktiga ämne. Perioder av tiaminbrist har observerats i flera olika djurgrupper, speciellt i högre trofiska nivåer. I Östersjön har tiaminbrist varit mest utbrett i lax (Salmo salar) och har på senare tid även rapporterats för andra fiskarter och fåglar. Denna avhandling fokuserar på dynamiken av tiamin i lägre trofiska nivåer, såsom primärproducenter men även primärkonsumenter eftersom den största delen av tidigare forskning fokuserat på de högre trofiska nivåerna. Tiamininnehållet i vanligt förekommande växt- och djurplankton samt överföringen av tiamin mellan de trofiska nivåerna har undersökts i både experiment och fältstudier. Sambandet mellan tiaminbrist och underliggande miljöfaktorer har även undersökts genom att flerårig övervakningsdata analyserats. Tiaminnivåerna skiljde sig åt mellan olika växtplanktonklasser, mellan arter och även mellan olika isolat av samma art. Filamentösa (trådformiga) cyanobakterier hade betydligt högre tiamininnehåll än övriga växtplankton. Dock var överföringen av tiamin lägre från cyanobakterier till djurplankton jämfört med andra arter, förmodligen på grund av svårigheter att konsumera filamenten. I övrigt så varierade partikulärt bundet tiamin (s.k. seston) säsongsmässigt och var högst under sommaren när både Prymnesiophyceae och filamentösa cyanobakterier utgjorde en stor del av växtplanktonsamhället. Det var en stark korrelation mellan tiaminnivåerna i de två olika storleksfraktionerna av seston och det var alltid högre koncentr
- Published
- 2019
39. Predicting Impacts of Climate Change on Sinjido Marine Food Web.
- Author
-
Yun Ho Kang, Se-Jong Ju, and Young-Gyu Park
- Published
- 2012
- Full Text
- View/download PDF
40. Reciprocal subsidies between freshwater and terrestrial ecosystems structure consumer resource dynamics.
- Author
-
Bartels, Pia, Cucherousset, Julien, Steger, Kristin, Eklöv, Peter, Tranvik, Lars J., and Hillebrand, Helmut
- Subjects
- *
LAND-water ecotones , *FRESHWATER ecology , *ECOSYSTEM dynamics , *PATCH dynamics , *MULTITROPHIC interactions (Ecology) - Abstract
Cross-ecosystem movements of material and energy, particularly reciprocal resource fluxes across the freshwater-land interface, have received major attention. Freshwater ecosystems may receive higher amounts of subsidies (i.e., resources produced outside the focal ecosystem) than terrestrial ecosystems, potentially leading to increased secondary production in freshwaters. Here we used a meta-analytic approach to quantify the magnitude and direction of subsidy inputs across the freshwater-land interface and to determine subsequent responses in recipient animals. Terrestrial and freshwater ecosystems differed in the magnitude of subsidies they received, with aquatic ecosystems generally receiving higher subsidies than terrestrial ecosystems. Surprisingly, and despite the large discrepancy in magnitude, the contribution of these subsidies to animal carbon inferred from stable isotope composition did not differ between freshwater and terrestrial ecosystems, likely due to the differences in subsidy quality. The contribution of allochthonous subsidies was highest to primary consumers and predators, suggesting that bottom-up and top-down effects may be affected considerably by the input of allochthonous resources. Future work on subsidies will profit from a food web dynamic approach including indirect trophic interactions and propagating effects. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
41. Coupled energy pathways and the resilience of size-structured food webs.
- Author
-
Blanchard, Julia, Law, Richard, Castle, Matthew, and Jennings, Simon
- Subjects
BENTHIC animals ,FOOD chains ,PREDATION ,MARINE ecology ,BIOTIC communities - Abstract
Size-based food-web models, which focus on body size rather than species identity, capture the generalist and transient feeding interactions in most marine ecosystems and are well-supported by data. Here, we develop a size-based model that incorporates dynamic interactions between marine benthic (detritus-based) and pelagic (primary producer based) pathways to investigate how the coupling of these pathways affects food web stability and resilience. All model configurations produced stable steady-state size spectra. Resilience was measured by the return speed obtained from local stability analysis. Return times following large perturbations away from steady-state were also measured. Resilience varied nonlinearly with both predator and detrital coupling, and high resilience came from predators (1) feeding entirely in the slow benthic zone or (2) feeding across the two energy pathways, with most food coming from the fast pelagic pathway. When most of the energy flowed through the pelagic pathway, resilience was positively related to turnover rate. When most of the energy flowed through the benthic pathway, resilience was negatively related to turnover rate. Analysis of the effects of large perturbations revealed that resilience for pelagic ecosystems depended on the nature of the perturbation and the degree of benthic-pelagic coupling. Areas with very little or no benthic-pelagic coupling (e.g. deep seas or highly stratified water columns) may return more quickly following pulses of detrital fallout or primary production but could be much less resilient to the effects of human-induced mortality (harvesting). [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
42. Relative importance of top-down and bottom-up forces in food webs of Sarracenia pitcher communities at a northern and a southern site.
- Author
-
Hoekman, David
- Subjects
- *
PREDATION , *SPATIAL ecology , *FOOD chains , *SARRACENIA , *PITCHER plants - Abstract
The relative importance of resources (bottom-up forces) and natural enemies (top-down forces) for regulating food web dynamics has been debated, and both forces have been found to be critical for determining food web structure. How the relative importance of top-down and bottom-up forces varies between sites with different abiotic conditions is not well understood. Using the pitcher plant inquiline community as a model system, I examine how the relative importance of top-down and bottom-up effects differs between two disparate sites. Resources (ant carcasses) and top predators (mosquito larvae) were manipulated in two identical 4 × 4 factorial press experiments, conducted at two geographically distant sites (Michigan and Florida) within the range of the purple pitcher plant, Sarracenia purpurea, and the aquatic community that resides in its leaves. Overall, top predators reduced the density of prey populations while additional resources bolstered them, and the relative importance of top-down and bottom-up forces varied between sites and for different trophic levels. Specifically, top-down effects on protozoa were stronger in Florida than in Michigan, while the opposite pattern was found for rotifers. These findings experimentally demonstrate that the strength of predator-prey interactions, even those involving the same species, vary across space. While only two sites are compared in this study, I hypothesize that site differences in temperature, which influences metabolic rate, may be responsible for variation in consumer-resource interactions. These findings warrant further investigation into the specific factors that modify the relative importance of top-down and bottom-up effects. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
43. Hidden diversity among aquatic heterotrophic flagellates: ecological potentials of zoosporic fungi.
- Author
-
Sime-Ngando, Télesphore, Lefèvre, Emilie, and Gleason, Frank H.
- Subjects
- *
HETEROTROPHIC bacteria , *FLAGELLATA , *AQUATIC ecology , *MICROBIAL diversity , *ZOOSPORIC fungi , *FOOD chains - Abstract
Since the emergence of the 'microbial loop' concept, heterotrophic flagellates have received particular attention as grazers in aquatic ecosystems. These microbes have historically been regarded incorrectly as a homogeneous group of bacterivorous protists in aquatic systems. More recently, environmental rDNA surveys of small heterotrophic flagellates in the pelagic zone of freshwater ecosystems have provided new insights. (i) The dominant phyla found by molecular studies differed significantly from those known from morphological studies with the light microscope, (ii) the retrieved phylotypes generally belong to well-established eukaryotic clades, but there is a very large diversity within these clades and (iii) a substantial part of the retrieved sequences cannot be assigned to bacterivorous but can be assigned instead to parasitic and saprophytic organisms, such as zoosporic true fungi (chytrids), fungus-like organisms (stramenopiles), or virulent alveolate parasites (Perkinsozoa and Amoebophrya sp.). All these microorganisms are able to produce small zoospores to assure dispersal in water during their life-cycles. Based on the existing literature on true fungi and fungus-like organisms, and on the more recently published eukaryotic rDNA environmental studies and morphological observations, we conclude that previously overlooked microbial diversity and related ecological potentials require intensive investigation (i) for an improved understanding of the roles of heterotrophic flagellates in pelagic ecosystems and (ii) to properly integrate the concept of 'the microbial loop' into modern pelagic microbial ecology. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
44. Structure-dependent, protistan grazing and its implication for the formation, maintenance and decline of plankton patches.
- Author
-
Menden-Deuer, Susanne and Fredrickson, Kerri
- Subjects
PHYTOPLANKTON populations ,PLANT populations ,FJORD ecology ,COASTAL ecology ,FOOD chains ,PREDATION - Abstract
The article discusses a study which confirmed the expectation that heterogenous distributions have long been recognized as potentially important factors in altering phytoplankton abundance and productivity estimates in a coastal fjord with naturally forming phytoplankton patches. The study identified phytoplankton patches using a fluorometer and sampled with a horizontally mounted 2 1 Niskin bottle in 3 separate field seasons in summer 2007 and 2008 and spring 2009. Data do not support the formation of plankton patches due to phytoplankton growth. Findings also indicate the importance of predator-prey interactions to the ubiquitous phenomenon of plankton patchiness and ultimately microbial food web dynamics.
- Published
- 2010
- Full Text
- View/download PDF
45. Stronger inducible defences enhance persistence of intraguild prey.
- Author
-
Kratina, Pavel, Hammill, Edd, and Anholt, Bradley R.
- Subjects
- *
FOOD chains , *ANIMAL ecology , *ANTIPREDATOR behavior , *ANIMAL defenses , *PREDATION - Abstract
1. Intraguild predation is widespread in nature despite its potentially destabilizing effect on food web dynamics. 2. Anti-predator inducible defences affect both birth and death rates of populations and have the potential to substantially modify food web dynamics and possibly increase persistence of intaguild prey. 3. In a chemostat experiment, we investigated the long-term effects of inducible defences on the dynamics of aquatic microbial food webs consisting of an intraguild predator, intraguild prey, and a basal resource. We controlled environmental conditions and selected strains of intraguild prey that varied in the strength of expressed inducible defences. 4. We found that intraguild prey with a stronger tendency to induce an anti-predator morphology persist for significantly longer periods of time. In addition, model selection analysis implied that flexibility in defensive phenotype (inducibility itself) is most likely the factor responsible for the enhanced persistence. 5. As patterns at the community level often emerge as a result of the life-history traits of individuals, we propose that inducible defences increase the persistence of populations and may contribute to the widespread occurrence of theoretically unstable intraguild predation systems in nature. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
46. Challenges and opportunities for integrating lake ecosystem modelling approaches.
- Author
-
Mooij, Wolf M., Trolle, Dennis, Jeppesen, Erik, Arhonditsis, George, Belolipetsky, Pavel V., Chitamwebwa, Deonatus B. R., Degermendzhy, Andrey G., DeAngelis, Donald L., Domis, Lisette N. De Senerpont, Downing, Andrea S., Elliott, J. Alex, Fragoso Jr., Carlos Ruberto, Gaedke, Ursula, Genova, Svetlana N., Gulati, Ramesh D., Håkanson, Lars, Hamilton, David P., Hipsey, Matthew R., 't Hoen, Jochem, and Hülsmann, Stephan
- Abstract
large number and wide variety of lake ecosystem models have been developed and published during the past four decades. We identify two challenges for making further progress in this field. One such challenge is to avoid developing more models largely following the concept of others (‘ reinventing the wheel’). The other challenge is to avoid focusing on only one type of model, while ignoring new and diverse approaches that have become available (‘ having tunnel vision’). In this paper, we aim at improving the awareness of existing models and knowledge of concurrent approaches in lake ecosystem modelling, without covering all possible model tools and avenues. First, we present a broad variety of modelling approaches. To illustrate these approaches, we give brief descriptions of rather arbitrarily selected sets of specific models. We deal with static models (steady state and regression models), complex dynamic models (CAEDYM, CE-QUAL-W2, Delft 3D-ECO, LakeMab, LakeWeb, MyLake, PCLake, PROTECH, SALMO), structurally dynamic models and minimal dynamic models. We also discuss a group of approaches that could all be classified as individual based: super-individual models (Piscator, Charisma), physiologically structured models, stage-structured models and trait-based models. We briefly mention genetic algorithms, neural networks, Kalman filters and fuzzy logic. Thereafter, we zoom in, as an in-depth example, on the multi-decadal development and application of the lake ecosystem model PCLake and related models (PCLake Metamodel, Lake Shira Model, IPH-TRIM3D-PCLake). In the discussion, we argue that while the historical development of each approach and model is understandable given its ‘leading principle’, there are many opportunities for combining approaches. We take the point of view that a single ‘right’ approach does not exist and should not be strived for. Instead, multiple modelling approaches, applied concurrently to a given problem, can help develop an integrative view on the functioning of lake ecosystems. We end with a set of specific recommendations that may be of help in the further development of lake ecosystem models. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
47. ENVIRONMENTAL FLUCTUATIONS INDUCE SCALE-DEPENDENT COMPENSATION AND INCREASE STABILITY IN PLANKTON ECOSYSTEMS.
- Author
-
Downing, Amy L., Brown, Bryan L., Perrin, Elizabeth M., Keitt, Timothy H., and Leibold, Mathew A.
- Subjects
- *
ECOLOGY , *POPULATION , *PLANKTON , *ZOOPLANKTON , *BIOTIC communities , *DENSITY , *PONDS - Abstract
The temporal stability of aggregate community and ecosystem properties is influenced by the variability of component populations, the interactions among populations, and the influence of environmental fluctuations on populations. Environmental fluctuations that enhance population variability are generally expected to destabilize community and ecosystem properties, but this will depend on the degree to which populations are synchronized in their dynamics. Here we use seminatural experimental ponds to show that reduced synchrony among zooplankton taxa increases the temporal stability of zooplankton density, abundance, and ecosystem productivity in fluctuating environments. However, asynchrony only occurs at long timescales (∼80-day periods) and under recurring environmental perturbations. At shorter timescales (∼10-day periods) and in constant environments, synchronous dynamics dominate. Our findings support recent theory indicating that compensatory dynamics can stabilize communities and ecosystems. They further indicate that environmental fluctuations can enhance the likelihood of long-period asynchrony and thus stabilize community and ecosystem properties despite their short term destabilizing effects. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
48. SHIFTING PREY SELECTION GENERATES CONTRASTING HERBIVORE DYNAMICS WITHIN A LARGE-MAMMAL PREDATOR-PREY WEB.
- Author
-
Owen-Smith, Norman and Mills, M. G. L.
- Subjects
- *
PREDATION , *LIONS , *HERBIVORES , *RAINFALL , *FOOD chains , *WATERBUCK , *ANIMAL carcasses - Abstract
Shifting prey selection has been identified as a mechanism potentially regulating predator-prey interactions, but it may also lead to different outcomes, especially in more complex systems with multiple prey species available. We assessed changing prey selection by lions, the major predator for 12 large herbivore species in South Africa's Kruger National Park. The database was provided by records of found carcasses ascribed to kills by lions assembled over 70 years, coupled with counts of changing prey abundance extending over 30 years. Wildebeest and zebra constituted the most favored prey species during the early portion of the study period, while selection for buffalo rose in the south of the park after a severe drought increased their vulnerability. Rainfall had a negative influence on the proportional representation of buffalo in lion kills, but wildebeest and zebra appeared less susceptible to being killed under conditions of low rainfall. Selection by lions for alternative prey species, including giraffe, kudu, waterbuck, and warthog, was influenced by the changing relative abundance and vulnerability of the three principal prey species. Simultaneous declines in the abundance of rarer antelope species were associated with a sharp increase in selection for these species at a time when all three principal prey species were less available. Hence shifting prey selection by lions affected the dynamics of herbivore populations in different ways: promoting contrasting responses by principal prey species to rainfall variation, while apparently being the main cause of sharp declines by alternative prey species under certain conditions. Accordingly, adaptive responses by predators, to both the changing relative abundance of the principal prey species, and other conditions affecting the relative vulnerability of various species, should be taken into account to understand the interactive dynamics of multispecies predator-prey webs. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
49. The ecology of chytrids in aquatic ecosystems: roles in food web dynamics.
- Author
-
Gleason, Frank H., Kagami, Maiko, Lefevre, Emilie, and Sime-Ngando, Telesphore
- Subjects
CHYTRIDIALES ,FOOD chains ,FRESHWATER ecology ,BIOTIC communities ,MYCOLOGY ,BIOLOGY - Abstract
Abstract: Chytrids are very important components of freshwater ecosystems, but the ecological significance of this group of fungi is not well understood. This review considers some of the significant environmental factors affecting growth and population composition of chytrids in aquatic habitats. The physical factors include primarily salinity, dissolved oxygen concentration and temperature. The biological factors include the role of chytrids as saprobes and parasites and methods of dispersal of propagules throughout the ecosystem. Dispersal depends upon both zoospores for short range and whole thalli for long range dispersal. Five roles for chytrids in food-web dynamics are proposed: (1) chytrid zoospores are a good food source for zooplankton, (2) chytrids decompose particulate organic matter, (3) chytrids are parasites of aquatic plants, (4) chytrids are parasites of aquatic animals and (5) chytrids convert inorganic compounds into organic compounds. New molecular methods for analysis of chytrid diversity in aquatic environments have the potential to provide accurate quantitative data necessary for better understanding of ecological processes in aquatic ecosystems. [Copyright &y& Elsevier]
- Published
- 2008
- Full Text
- View/download PDF
50. UNDERAPPRECIATED SPECIES IN ECOLOGY: "UGLY FISH" IN THE NORTHWEST ATLANTIC OCEAN.
- Author
-
Link, Jason S.
- Subjects
FISHES ,FISH evolution ,FISH research ,AQUATIC animals ,SKATES (Fishes) ,COTTIDAE ,LOPHIIDAE - Abstract
The article presents a research on the understudied species of fish in the northeast U.S. Atlantic ocean. It mentions the examination of various species of the skates, cottids, anarhichadids, lophiids, zooarcids and other similar fish to determine the changes in their abundance in the past four decades. It also discusses how the distribution and stomach contents of these species were evaluated to find out their importance and another evaluation on the evidence for its sequential depletions and ramifications.
- Published
- 2007
- Full Text
- View/download PDF
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