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Conservation of ecosystem engineers, which modulates the surrounding habitat by causing physical state changes in biotic or abiotic materials, is important for maintaining the functional integrity of ecosystems. This study examined the effects of endangered freshwater pearl mussels (Margaritifera laevis and M. togakushiensis) on channel morphology and flow in a low-gradient sandy river. For this, we performed a field removal experiment of mussels using three treatments in twelve 10-m reaches. Mussel abundance and biomass, and three physical variables were measured before, immediately after, and two months to one year after the treatments. Mussel removal resulted in channel degradation with a 60% increase in flow depth, a 30% decrease in current velocity, and a 50% reduction in the width-to-depth ratio two months after the treatments, whereas minimal changes were measured in reaches with mussels. The results indicated that pearl mussels act as an ecosystem engineer affecting the channel morphology and flow of sandy rivers. The conservation of the pearl mussel populations is key to preserving their far-reaching benefits in ecosystem integrity including habitats for other various organisms.

Outcomes of predator–prey interactions depend on biotic and abiotic factors. Habitat complexity, for example, mediates predator functional response type and parameters (attack rate and handling time). However, the relationship between habitat complexity and functional response varies across ecosystems. We assessed interactions between the giant water bug, Belostoma sp., and its prey, rams-horn snails, Helisoma trivolvis, across four prey densities (N = 2, 4, 8, 16 snails) and three habitat complexity levels (No-complexity, Low-complexity, High-complexity) to understand how complexity affected the functional response. We also tested effects of predator and prey body size on number of prey killed. Belostoma exhibited a Type III functional response in all habitat complexity treatments. Attack rate tended to increase with increasing complexity. Handling time was different among treatments, being lowest in the No-complexity treatment and highest in the Low-complexity treatment. Belostoma body size was positively related, while Helisoma body size was inversely related, to the number of Helisoma killed. We show habitat complexity does not affect the shape of predator functional response but impacts response parameters in the Belostoma–Helisoma system. We reaffirm that attack rate, handling time, and mortality outcomes for prey within predator–prey interactions are affected by abiotic factors through habitat complexity.

Instream hydraulics and riverbed substrate allow for the identification of mesohabitats, and contribute in shaping benthic macroinvertebrate assemblages. However, the role of different depositional conditions between mesohabitats in determining macroinvertebrate response to large sediment input still needs investigation. We studied the evolution of sediment deposits and benthic assemblages in two mesohabitats (a riffle and a glide) of an Alpine river affected by an extreme sediment input. Substrate and hydraulic characteristics were measured in each mesohabitat for 18 months after the sedimentation event. Benthic macroinvertebrates were sampled concurrently, and available pre-event data allowed for before/after comparison. We found evidence of a different response of benthic communities to siltation, associated to the physical structure of the mesohabitat they inhabit. Both substrate and macroinvertebrates were less impacted and recovered faster in the riffle than in the glide. Assemblages in the glide adjusted to the modified habitat through strong proliferation of sand tolerant and preferring families, resulting in higher density and lower diversity compared to the riffle. Our results could support the improvement of the impact assessment of sediment input events. This is particularly relevant given the current global warming, inducing the increase in frequency and intensity of severe rainfall events, and subsequent landslides.

We assessed how the variation in environmental factors influences mayfly assemblages in conserved streams of different Amazonian interfluves. We hypothesized that environmental variables, mayfly assemblages, and the influence of environmental factors vary among these interfluves, given their distinct evolutionary and ecological histories, and patterns of human interference. We also expected that the effects of environmental variation on species richness and composition would be greater among interfluves than among streams within the same interfluve. Our hypotheses were corroborated, reflecting the considerable heterogeneity of the Amazonian biome, where streams vary naturally among interfluves, determining broad scale divergences in species composition. The environment affected mayfly diversity in different ways among interfluves, reflecting the influence of historical processes that resulted in the formation of centers of endemism delimited by major Amazonian rivers, in which distinct biotic and abiotic factors have prevailed. These regional effects have resulted from the heterogeneity of environmental gradients, which affect mayfly diversity. The results of the present study indicate that, depending on the scale and topography of the interfluve, environmental predictors of the structure of mayfly assemblages vary considerably. This has important implications for the definition of control sites for the assessment and monitoring of environmental quality.

The aim of this review is to summarize the literature knowledge about how abiotic environmental factors and biotic interactions affect the sequentially overlapping longitudinal distribution of Central European species of the net-spinning freshwater caddisfly larvae of the genus Hydropsyche (Trichoptera: Hydropsychidae). In this relation, several physical and chemical parameters of water are discussed, as well as different species-specific traits, behavioural aspects and the interaction of coexisting species. Longitudinal gradients of river networks, especially annual temperature range, flow velocity and the particle size of suspended food material play a crucial role in forming the downstream succession of characteristic species, while increased levels of organic pollution, nutrients, salinity and heavy metals facilitates the presence of more tolerant ones. Several species-specific traits, such as respiration range, net-building frequency, head capsule size or optimal net-building velocity correlate with the position of a given species in the sequence. Coexistence of species with similar ecological demands in the overlapping zones of distribution is facilitated by differences in feeding and net-building habits, microhabitat preferences and staggering life cycles, but complicated at the same time by means of inter- and intraspecific territorial behaviour, such as fighting for the ownership of larval retreats or the practice of stridulation.

Large river management is in increasing demand to establish the ecological quality set by sustainability-oriented legislation. However, there is still a lack of research regarding most relevant scales at which pressures should be addressed. In this study, we compared the relative effects of riparian land-cover at 16 different buffer sizes and hydromorphology at four different river lengths on benthic invertebrate (BI) and fish assemblages in large rivers. Environmental data were obtained digitally (applying GIS) on a broad range of abiotic conditions and were related to biological data using direct gradient analyses. Compared to land-cover, hydromorphology showed greater effect on BI and fish, with in-channel habitat quality characteristics explaining most biotic variability. Both assemblages were best explained by hydromorphology inventoried at the largest 5,000 m scale. We found, however, consideration of longer river segments to be more important for explaining fish variability. Riparian land-cover explained similar percentages of biotic variability across most analysed riparian buffers. Nevertheless, a significant effect of riparian length rather than width was identified. Our findings indicate that, in large rivers, hydromorphological and riparian land-cover conditions affect BI and especially fish at generally longer river segments, implying potential ecological benefits of management measures implemented at larger spatial scales.

β-Diversity can be driven by different factors, and it is necessary to understand how the characteristics of communities contribute to biodiversity. We investigated composition patterns and taxonomic and functional β-diversity, in addition to determining the possible processes driving the β-diversity of zooplankton in 42 lakes, distributed in two regions with distinct rainfall patterns, a semiarid and a humid region both in the Brazilian Northeast. Environmental heterogeneity was higher in the semiarid region. The species composition was different; however, taxonomic and functional β-diversity did not differ between regions. These data sets showed that although the composition was distinct, the change in species and traits occurred similarly. Taxonomic and functional β-diversity were driven by environmental factors. They showed a predominance of niche assembly and the importance of abiotic variables in the selection of species and traits. In our case, the dispersion limitation did not influence β-diversity. Species are deterministically filtered, and each region imposes a distinct environmental filter that selects them. Due to the limited studies on the partition of functional β-diversity and the uncertainty of ecological patterns for intermittent environments, more scientific research is required that considers this approach for dry regions and over longer time periods.

River–floodplain systems are characterized by high connectivity, which favours the spread of non-native species. In floodplain, floods increase connectivity, which increases the similarity of abiotic conditions among environments. High connectivity and low environmental variability may favour the establishment of non-native species such as Limnoperna fortunei, but this has not yet been tested. We sampled L. fortunei larvae in nine connected lakes and nine isolated lakes to rivers in the upper Parana River floodplain to evaluate how spatial (connection) and abiotic (environmental variability) factors affect the larvae density of L. fortunei. We considered the rivers as propagule source of L. fortunei because this invasive species has successfully established in rivers, but not in lakes. Our findings revealed that connected lakes had a high larval density of L. fortunei, while isolated lakes had a low density. Isolated lakes presented a high multi-environmental variability, which was strong negatively related with the larval density of L. fortunei. However, the connectivity decreased the multi-environmental variability, indirectly increasing the larval density of L. fortunei. Our study illustrates that permanent connectivity with invaded environments increase the larvae density of L. fortunei in non-invaded environments, which occurs both directly (through propagule dispersion) and indirectly (by decreasing multi-environmental variability).

Freshwater snails act as intermediate hosts (IH) for schistosomiasis, a tropical disease affecting over 200 million people worldwide. Despite their medical importance, an extensive understanding of IH snail ecology remains absent. Especially data on the tolerance limits to different abiotic factors are fragmented and incomplete. Consequently, the construction of accurate species distribution models to identify snail habitats and guide targeted snail control efforts remains difficult. Here, we compiled a summary on the tolerance limits to abiotic factors of African IH snails of human schistosomiasis. A systematic search on Web of Science, PubMed, and Embase identified 45 relevant studies. Synthesis of these studies indicates that research efforts differ greatly between IH snail species, life stages, and abiotic factors. The importance of each abiotic factor in determining snail presence and abundance is discussed. Furthermore, attention was drawn to knowledge gaps and the lack of standardised experimental designs, which impedes comparisons between studies. This in turn prevents us from making firm conclusions and calls for best practices adopted by all malacologists. In doing so, IH snail ecological data could serve as a basis to assess schistosomiasis risk and guide snail control efforts in order to support schistosomiasis control. ispartof: Hydrobiologia vol:848 issue:8 pages:1773-1793 status: Published online

Processes associated with reservoir aging threaten the capacity of systems to continue providing productive fisheries, and declining productivity might be exacerbated by decreasing water level associated with climate change and water abstraction. Despite their prevalence in riverscapes, we know little about long-term fish dynamics in reservoirs. Using a 38-year dataset from Lake Powell, USA, we tested for changes in assemblage structure and changes in fish condition for the most abundant species. The assemblage has undergone re-ordering of species relative abundance, but the same core species captured in 1981 were still present in 2018. Five species increased in relative abundance, while two declined, and seven remained unchanged. Walleye Sander vitreus and Smallmouth Bass Micropterus dolomieu were among those increasing over time, while Channel Catfish Ictalurus punctatus and Common Carp Cyprinus carpio declined. We were not able to attribute changes in fish assemblages with a suite of abiotic and biotic variables. Condition was low and declined over time for four of the six species. Although water level declined over time, we did not observe obvious declines in basal food resources. Declining water level has reduced availability of littoral habitat and likely contributed to declines in some species associated with this zone.

Large-scale deforestation not only modifies the landscape, but also affects in the structure of the habitat, and threaten the functional structure of the aquatic biota. This study evaluates the partitioning of the functional beta diversity of stream fish along a gradient of environmental impact and determines which functional traits are associated with the gradient. Biological, environmental, and landscape variables were sampled in 2014 and 2015. The functional structure of the fish fauna was characterized using 12 functional traits. The functional beta diversity and functional replacement were influenced by changes in local abiotic and landscape conditions, caused by modifications in forest cover, with the functional traits varying systematically in accordance with environmental features. We found no association between environmental variables and functional traits. Our results raise concerns with regard to the transformation of the landscapes in which streams are found caused by changes in land use, and we would recommend the preservation of an adequate buffer of good quality riparian vegetation in management or restoration projects to guarantee the long-term conservation of stream ecosystems.

International audience; Invasive alien aquatic plant species (IAAPs) cause serious ecological and economic impact and are a major driver of changes in aquatic plant communities. Their invasive success is influenced by both abiotic and biotic factors. Here, we summarize the existing knowledge on the biology of 21 IAAPs (four free-floating species, eight sediment-rooted, emerged or floating-leaved species, and nine sediment-rooted, submerged species) to highlight traits that are linked to their invasive success. We focus on those traits which were documented as closely linked to plant invasions, including dispersal and growth patterns, allelopathy and herbivore defence. The traits are generally specific to the different growth forms of IAAPs. In general, the species show effective dispersal and spread mechanisms, even though sexual and vegetative spread differs strongly between species. Moreover, IAAPs show varying strategies to cope with the environment. The presented overview of traits of IAAPs will help to identify potential invasive alien aquatic plants. Further, the information provided is of interest for developing species-specific management strategies and effective prevention measures.

The present study evaluated the effects of habitat quality on the alpha and beta diversity of odonate larvae under conditions of reduced impact and conventional logging. We hypothesized that the variation in the abiotic conditions found in areas of conventional logging would result in a greater loss of alpha and beta diversity in these areas in comparison with areas of reduced-impact logging and native forest. The study area was located in northeastern Para state, in northern Brazil. We analyzed data from 10 control streams, located in areas of preserved native forest, 11 streams in forest harvested by reduced-impact logging, and nine streams in areas that had been logged conventionally. Environmental factors such as dissolved oxygen, woody debris, water temperature, sediments, and canopy cover were the principal predictors of the diversity of the Odonata. Our results showed that turnover was the principal component structuring beta diversity in the three areas (native forest, reduced impact and conventional logging). The results of the present study indicate that management initiatives based on reduced-impact logging techniques could be adopted to guarantee socio-economic benefits while minimizing the impacts of logging on local biodiversity.

While warming and eutrophication have increased the frequency and magnitude of harmful cyanobacterial blooms globally, the scenario for many eutrophic tropical freshwaters is a perennial year-round bloom. Yet, the drivers of persistent blooms are less understood when conditions such as light, temperature, and nutrients favor cyanobacteria growth year-round, and especially in regions facing recurrent periods of drought. In order to understand the drivers of cyanobacteria dominance, we assessed the abiotic conditions related to the abundance and dominance of the two dominant bloom-forming genera Raphidiopsis and Microcystis, in six shallow, man-made lakes located in the semiarid Northeastern region of Brazil during a prolonged regional drought. Lower water level corresponded to increased phosphorous and nitrogen concentration and, consequently, phytoplankton biomass. Cyanobacterial biomass was also proportional to phosphorus concentrations during year-round blooms. Yet, the two dominant cyanobacterial genera, Raphidiopsis and Microcystis, seldom co-occurred temporally and the switch between them was driven by water transparency. Our results illustrate the effects of drought induced water level reductions on the biomass and composition of cyanobacterial blooms in tropical shallow man-made lakes. Given the ideal year-round conditions (i.e., high light and temperature), droughts may be expected to intensify the risk and multitude of problems associated with eutrophication.

Danube Delta shallow lakes experience cyanobacteria blooms that can negatively affect the aquatic ecosystem. Although there are several studies on Danube Delta cyanobacteria, little is known about their spatial–temporal patterns and the potential predictive role they can offer. We therefore analyzed the distribution of cyanobacteria in 19 lakes belonging to three lake complexes and tested whether their seasonal dynamics are in line with the predictions of the PEG model. Furthermore, we investigated to which extent cyanobacteria diversity and abundance were related to lake hydrogeomorphological characteristics such as surface, water level, connectivity, water retention, flood risk, and transparency. Although lakes had different seasonal cyanobacterial assemblages, the biovolume and genus richness had a geographical pattern, decreasing from south-east (lakes forming the fluvial delta) towards north-west (lakes forming the maritime delta). Cyanobacteria biovolume reflected largely the PEG model peaking in summer (the fluvial delta) and autumn (the maritime delta). Genus richness followed the same pattern. Cyanobacteria distribution was predicted by various abiotic (e.g., risk of flooding, connectivity) and biotic factors (e.g., submersed macrophytes, phytoplankton diversity, peat deposits). Our study contributes to the understanding of cyanobacteria diversity and distribution in shallow interconnected lakes by revealing the complexity of predictors for geographical and seasonal patterns.

Species invasions often occur on coasts and estuaries where abiotic conditions vary, e.g. salinity, temperature, runoff etc. Successful establishment and dispersal of non-indigenous species in many such systems are poorly understood, partially since the species tend to show genetic and ecological plasticity at population level towards many abiotic conditions, including salinity tolerance. Plasticity may be driven by shifting expression of heat shock proteins such as Hsp70, which is widely recognized as indicator of physical stress. In this study, we developed a qPCR assay for expression of the hsp70 gene in the invasive round goby (Neogobius melanostomus) and tested the expression response of fish collected from a brackish environment in the western Baltic Sea to three different salinities, 0, 10 and 30. hsp70 expression was highest in fresh water, indicating higher stress, and lower at brackish (ambient condition for the sampled population) and oceanic salinities, suggestive of low stress response to salinities above the population’s current distribution. The highest stress in fresh water was surprising since populations in fresh water exist, e.g. large European rivers and Laurentian Great Lakes. The results have implications to predictions for the species’ plasticity potential and possible range expansion of the species into other salinity regimes.

Veredas environments play a critical role on the perennialization of streams in the Cerrado Biome, but alterations to their physiognomies are becoming increasingly more common, which directly affects abiotic variation and the structure of biological communities. Our study evaluates the effect of abiotic variations and environmental alterations upon the abundance, richness, and composition of species of semiaquatic bugs, where we test whether there are significant differences in conserved and altered veredas. Species richness was higher on altered veredas and there was no difference in abundance between altered and preserved veredas. The composition of conserved veredas was more homogeneous. Five species were associated with altered veredas and one to conserved areas. There were abiotic changes in the veredas that affected the abundance, richness, and/or composition of Gerromorpha. Ease of access to soil usage and to water for farming activities and pasture might be the main factors contributing to the alteration of veredas in this region. Gerromorpha community structure was modified by the environmental passive in areas of veredas, thus allowing to measure the degree of alterations to these systems, being a useful tool for monitoring and conservation.

Silica (Si) plays a significant role in alleviating the effects of biotic and abiotic stressors in many plants, especially in an agricultural context. With increased use of Si-based fertilisers, understanding plant responses to the addition of Si to their environment, particularly aquatic environments, is important. We investigated how two invasive macrophytes, Eichhornia crassipes and Pistia stratiotes, responded to different nutrient and Si concentrations, in the presence and absence of herbivory. Both species incorporated Si into their foliage, but uptake of Si did not increase under high nutrient availability but rather decreased, especially in P. stratiotes. Plant quality (i.e. C:N) for both weed species was affected more by nutrient concentrations than Si content, and the addition of Si had a negative effect on plant growth. Eichhornia crassipes increased daughter plant production under high Si conditions, while P. stratiotes plants showed no reproductive response to increased Si except in low nutrient conditions where reproduction was reduced. The addition of Si resulted in increased biomass of E. crassipes, while P. stratiotes was unaffected. These results highlight that runoff of Si from fertiliser alter aquatic plant–insect interactions, which has consequences for biological control.

Water hyacinth, Eichhornia crassipes (Mart.) Solms (Commelinales: Pontederiaceae), is an important aquatic weed worldwide. Previous studies demonstrate that releases of Neochetina bruchi Hustache (Coleoptera: Curculionidae) provide biological control in many locations, but not all. Notably, N. bruchi were unsuccessful at regulating water hyacinth in tidal brackish waters. Abiotic factors, including salinity and nutrients, affect water hyacinth growth, but little is known about the impact of salinity on weevil survival. We hypothesized that N. bruchi has a relatively low salinity tolerance. In a mesocosm experiment, we assessed weed growth in response to a range of salinity and nutrient concentrations. In a laboratory, we assessed adult N. bruchi mortality in response to various salinity concentrations. Results indicate that increasing nutrient concentration increases weed growth. When both nutrient and salinity levels were varied, nutrients increased leaf count, but not biomass, while salinity reduced growth and increased mortality. Increasing salinity concentrations increased adult weevil mortality; required concentrations were higher than that for weeds. Thus, these results did not provide support for the suggested hypothesis. Potential effects of salinity via other exposures to weevils need to be investigated. Elucidating abiotic factors important for weed growth and weevil survival may increase effectiveness of water hyacinth management practices.

Community assembly (CA) is a topic of growing interest in ecology due to global change, among other reasons. A review of the latter 20 years in plankton CA studies suggests some advancements and drawbacks. Most works deal with groups of same trophic level species and overlook food webs, except the proposal of the PEG model. Phytoplankton has focused the most on theoretical grounds of CA: (i) to find species associations and establish their templates (condition and resource matrices) in order to define assembly rules, (ii) to set the main assembling mechanisms arising from mean-trait studies and environmental constraints, and (iii) to debate on the predictable ability of that view. After the last decade of advancements, CA future will certainly foster not only by considering classical ecological mechanisms (abiotic selection, biotic interactions, history), but also by including evolutionary and metacommunity (i.e. regional) processes. Massive DNA metabarcoding of taxa, incorporation of novel traits (such as the proportional growth rate), consideration of non-dominant species and experimentation on templates and trajectories will certainly tune up and widen our view of CA, a topic very earlier tackled successfully by Colin Reynolds.

Microbialites are microbial communities that create a carbonate structure. They are abundant in the Great Salt Lake, a hypersaline lake in the arid Great Basin of the USA, where they contribute to overall primary production, seasonally up to 55%. While the microbial diversity of microbialites has been investigated, how abiotic factors affect the abundance of their primary constituents is not well understood. We examined how microbialite primary producers respond to varying levels of temperature, salinity, and nitrogen within ranges observed in the Great Salt Lake. All abiotic factors and their interactions significantly affected the maximum chlorophyll-a abundance, suggesting that these factors co-limit microbialite primary producers in the Great Salt Lake. Maximum chlorophyll-a concentrations increased with nitrogen additions and showed a parabolic relationship with salinity and temperature with peaks around 60 ppt and 20°C, respectively. While salinity had a strong effect on microbialite primary producers, we found that temperature and nitrogen were more impactful, accounting for 40 and 30% of the variance in maximum abundance, respectively, while salinity contributed just 15%. Our results show the importance of the interplay of abiotic factors on Great Salt Lake microbialites and highlight the need for increased study of benthic communities in inland saline lakes.

Knowledge of factors affecting the diversity of benthic invertebrates is very important for biodiversity conservation, for monitoring, restoring and maintaining aquatic ecosystems. The purpose of this study was to investigate how the diversity and distribution of freshwater mollusks related to environmental factors. Twelve species of freshwater mollusks were identified during a survey of 15 thermokarst lakes in the Gydan Peninsula, Russia. Canonical correspondence analysis (CCA) was used to study the relationships between environmental variables and species abundance. The first CCA axis correlated with the content of macro-ions, mainly Mg2+, Na+, Cl−, substrate types, and plant remnants. Along the second CCA axis stations were ordered by depth and the presence of mosses. We found that the type of substrate, depth, abundance of mosses and hydrochemical parameters play an important role in the distribution of the mollusks in thermokarst lakes. These results expand our understanding of mollusks ecology in thermokarst lakes, and identify environmental stressors important for the performance of abiotic control.

Otter diet in reservoirs is known to experience seasonal changes. We selected a reservoir with a large population of exclusively wintering great cormorants and seasonal changes in stored water volume to test the relative influence of abiotic and biotic factors on otter foraging ecology. DNA metabarcoding of otter spraints revealed a dietary change from autumn to winter. Otters had a diet dominated by the exotic goldfish in autumn, but predated intensively on the native northern straight-mouth nase in winter. This change was likely caused by predation of cormorants on goldfish and to fish biology. Secondly, macroscopic analysis of spraints revealed that otters shifted from a diet dominated by fish (in terms of biomass) to a diet dominated by red swamp crayfish during spring–summer, when the latter became overabundant. As revealed by modelling, this second shift was most likely influenced by the sudden increase in stored water volume in spring, but also by the cumulative effect of cormorant predation on fish during autumn–winter. Macroscopic analyses of otter spraints collected in a second reservoir with no cormorants revealed a lack of seasonality. Hence, the combined influence of both biotic and abiotic factors explained otter diet seasonality in a lentic-water novel ecosystem.

Water-level fluctuations are common abiotic stresses influencing growth and physiological processes of wetland plants. Nonetheless, little is known about plant eco-physiological responses and growth strategy under multi-hydrological processes. Carex schmidtii was grown under the conditions with interaction of initial water-level depth (DW) and water-level amplitude (AW). Dynamics of plant eco-physiological traits and growth strategy were investigated continuously during the entire growth stages. Results indicated that leaf morphology was significantly affected by DW and lasted time, and leaf width was sensitive to AW. The SLA and LDMC of C. schmidtii varied significantly at different lased time, and their relationships indicated the trade-off in leaves between matter production and nutrient conservation. Increasing DW inhibited matter production of C. schmidtii in early growth stage, but increased nutrient conservation in late growth stage. However, increasing AW contributed to both increase of matter production and nutrient conservation of C. schmidtii. The photosynthetic pigments of C. schmidtii are relatively sensitive to DW, AW and their interaction. Slowing down water-level fluctuations and appropriate water management in the key growth stage will assist with the adaption of Carex schmidtii. The findings provide invaluable supporting information for the management and conservation of C. schmidtii tussock wetlands.

International audience; Understanding the relative importance of habitat and biotic drivers on community assembly across food web components is an important step towards predicting the consequences of environmental changes. Because documenting entire food webs is often impractical, this question has been only partially investigated. Here, we partitioned variation in species assemblages of the major components of tank bromeliad food webs (bacteria, algae, protozoans, detritivorous and predatory invertebrates) into habitat and biotic determinants and examined the influence of habitat variables and predator or prey abundance on all taxonomic assemblages. Ecological determinism of assemblage structure ranged from weak in bacteria (

Our aim was to investigate whether there is a relationship between abiotic factors and the morphological diversity (MD) of Odonata larvae by building an ecomorphological index in oil palm plantation areas with riparian vegetation in the Eastern Amazon. We hypothesised that the MD of Odonata larvae might be affected by oil palm plantation since changes in the landscape might cause the loss of microhabitats that are essential for the larval life cycle. A total of 950 Odonata larvae were collected in 11 streams located in a continuous forest area (inside the legal reserve) and 18 streams located in oil palm streams surrounded by riparian vegetation. There was a significant difference in the MD of the larvae between the oil palm and forest areas. When we compared the results obtained using traditional measures of biodiversity (estimated species richness) with those obtained using the measure of MD, MD was more efficient. The RLQ tests showed a significant relationship between genus abundance and environmental variables, and between genera and morphological traits. We believe that the suppression or change in riparian vegetation might increase the sediment load input and decrease the amount of plant substrate available in the system, leading to the simplification of morphological traits. Therefore, such traits might be used as indicators of environmental impact.

The mosquito Aedes phoeniciae is a potential disease vector that inhabits the coastal rock-pools of the Southeastern Mediterranean Sea. Our year-long study examined the abundance and distribution of Ae. phoeniciae in 49 rock-pools along HaBonim Beach Nature Reserve (Israeli coast) on a monthly basis (September 2016 to August 2017). Additionally, the physical, chemical, and biological characteristics of the rock-pools were measured. Our results showed a correlation between the abundance of Ae. phoeniciae and abiotic (salinity, pool volume, and pH) and biotic (bacterial, micro-phytoplankton, and chironomid abundance) characteristics. A complementary experiment was conducted to examine the role of bacteria and phytoplankton on Ae. phoeniciae larval performance by rearing larvae in seawater (SW) or seawater without microbes (FSW, 0.2-µm). Ae. phoeniciae grown in SW exhibited a high survivorship rate (~ 77%), while lower survivorship rate was measured in the FSW treatments (~ 45%). Furthermore, a higher number of adult females were found in the SW compared to FSW treatments (35 and 11, respectively), while the number of male adults remained similar. Our results suggest that Ae. phoeniciae larvae rely on the water characteristics and especially on the microbial communities that habitat the rock-pools. These results may enable improved mosquito control of Ae. phoeniciae along the Southeastern Mediterranean Sea.

Climate change has been associated with alterations in temperature and precipitation regimes. Increased temperatures can change the structure and function of aquatic communities through both biotic and abiotic interactions. Many warming experiments have been conducted in permanent freshwater systems, but few in temporary freshwater systems that are dependent on precipitation patterns. Temporary aquatic communities are influenced by hydro-regime characteristics such as the hydroperiod length, magnitude, frequency, and timing of inundation, which may interact with temperature changes. Here, we used mesocosms to test for the effects of warming and inundation timing on the community composition of California vernal pools. California vernal pools are temporary wetlands, which provide habitat for many endemic and endangered species during the aquatic phase. Total species abundance was higher in both warm and late inundation treatments, while higher species richness levels in late treatments were due to the rapid emergence and colonization of species compared to early treatments. Heating increased the abundance of ubiquitous passive and active dispersers, including mosquitos, but decreased the abundance of vernal pool endemic passive dispersers. We also found that significant interactive effects between warming and inundation timing led to differences in community composition. These findings suggest that vernal pool endemic passive disperser species may decline due to increased temperatures and later inundation; however, the extent of such risk will likely be influenced by species-specific life-history traits such as bet-hedging strategies. Conservation efforts should work to identify the species most at risk to a changing climate.

Olindias sambaquiensis and Rhacostoma atlanticum are the most abundant species of macrohydromedusae on the southern coast of Brazil; the first is associated with outbreaks of stings in bathers during the summer, and the second with interference in fishing. Due to their direct relationship with human activities, their life cycles were investigated, using laboratory cultivation and study of their cohorts in the field, as well as the patterns of abundance in light of the abiotic and biotic factors of the study area. The coexistence of the two species is possible due to differences in their life cycles, duration of the polyp phase, and the formation of well-defined cohorts. Variations in abundance of the species from one year to another cannot be explained by abiotic variables alone, such as seawater temperature, but may also be associated with the balance between these and other biotic forces, such as local production and, possibly, effects of competition between species. However, on a monthly scale, the aggregations of O. sambaquiensis in southern Brazil appear to be associated with the lowest frequency of north quadrant winds, which could, in addition to promoting resurgence processes, lead to dispersion of the organisms off the coast.

Indices based on community structure provide a global ecological status of the biological communities but they are of limited value as early-warning indicators of contamination. Almost two decades after the Water Framework Directive (2000/60/EC) was adopted, we reviewed publications that measured biomarkers in benthic macroinvertebrates in biomonitoring programmes of fluvial systems. The focus was on studies that attempted to incorporate both biomarkers and community-based approaches in the evaluation of the ecological status of rivers and streams. Overall, the data showed that biomarker measurements in benthic macroinvertebrate species can offer complementary information on the factors threatening these communities. This information is particularly useful for water authorities, in order to take actions before a system collapses into a state from which recovery is difficult or impossible. Gaps in need to be addressed for rapid and efficient implementation of biomarkers in benthic macroinvertebrates in routine wide-scale monitoring are discussed. In particular, site-specific baselines have to be defined, taking into account the influence of biotic and abiotic factors on these biochemical responses. Further studies, including different biomarkers, environmental stressors, macroinvertebrate taxa and river types, will provide crucial information on how to establish adequate biomarker strategies to indicate future ecological damage.

Bythotrephes longimanus is an invasive zooplankton predator, negatively impacting zooplankton abundance and diversity in North American lakes. Previous studies have shown that Daphnia populations in lakes move to deeper waters during the day, in the presence of Bythotrephes, a visual predator occupying well-lit regions. However, Daphnia vertical position can be influenced by a variety of biotic and abiotic factors. We conducted a survey to determine (1) if Daphnia daytime vertical position differed between invaded and uninvaded lakes and (2) if Daphnia vertical position in invaded lakes was affected by water chemistry variables linked to water clarity, UV exposure, and phytoplankton production, and Bythotrephes density. Invaded lakes had a lower proportion of epilimnetic Daphnia as compared to uninvaded lakes. Daphnia vertical position was species-dependent, and with a lower proportion of epilimnetic Daphnia mendotae and greater proportion of epilimnetic D. longiremis observed in invaded lakes. D. mendotae were deeper in the water column in high Bythotrephes density lakes with low dissolved organic carbon levels. Our results show Daphnia vertical position response to Bythotrephes is species specific, dependent on Bythotrephes density and influenced by local abiotic conditions, with important implications for community structure and ecosystem function in invaded lakes.

While several studies have tested the effects of anthropogenic factors on specific taxa in ponds, the simultaneous effects of the overall anthropogenic pressure along the environmental gradient on the diversity of different groups of pond communities remain unknown. In this study, we evaluated the simultaneous effects of the overall intensity of human impact and characteristics of natural pond variability on the diversity and density of macrophytes, benthic and epiphytic macroinvertebrates, and fish community and water chemistry in pond ecosystems. We found a reduction in the diversity and density of macrophytes and in the diversity of epiphytic macroinvertebrates with an increased human pressure. The effects of the intensity of human impact on the diversity of epiphytic macroinvertebrates were mediated via changes in macrophyte diversity. Benthic macroinvertebrates were not affected by an increase in the intensity of human pressure. Fish community responded to the increased human pressure with shifts in abundance through the predominance of invasive species. Natural pond variability properties affected the pond communities and water chemistry in the majority of cases. Our results conclude that for understanding the effects of human activity on pond biodiversity, integrating the simultaneous effects of multiple anthropogenic and abiotic factors in ponds is desirable.

The aim of this study was to determine microcrustacean secondary production (P/B) and a herbivory ratio (ZB:PB) in the River Danube and a floodplain lake to reveal models in plankton food web functioning. P/B was used to assess population variation under different environmental conditions, while ZB:PB provided information on the zooplankton grazing intensity on algae. Seasonal changes, displayed by the hydrological regime, i.e., related water level fluctuation, were expected to explain different plankton patterns between the study sites as a result of unlike community composition and food quality. The structural equation modelling we used identified specific pathways of measured indexes at the individual localities. Although the direct impact of water level fluctuation on the studied communities was low, the following difference in abiotic components might have caused shifts in zooplankton assemblages that changed P/B and ZB:PB ratios. In the floodplain lake, P/B was primarily influenced by biotic components, and herbivory alteration was expressed through top-down control. On the contrary, P/B in the riverine system was controlled by an environmental element and herbivory was driven by the bottom-up resources. The results show the usefulness of the studied indexes in determining variations of zooplankton functional processes in the hydrologically dynamic environments.

Aquatic invertebrates can be geographically dispersed by abiotic vectors (wind, rain and water flow) or organisms (mainly by insects, fishes and waterbirds). However, there is a lack of information on the dispersal by waterbirds of cladocerans and especially rotifers, and on the hatching success of the dispersed propagules. Here, we quantify the dispersal of cladocerans and rotifers by waterbirds through analysis of their faecal droppings collected in a wetland formed by two natural lakes located in Donana National Park (Spain). We also study the influence of different photoperiod and temperature conditions on the hatching success of the dispersal propagules. Diapausing propagules of 22 species of rotifers or cladocerans were identified in waterbird faecal droppings, with a mean number of 0.9 diapausing propagules per dropping. The hatching success rate, which was not influenced by photoperiod or temperature, was low (~ 12.5%). Nevertheless, the role of rotifer dispersal by waterbirds appears to have been underestimated in the past. In this study area, the dispersal of rotifers by waterbirds may be at least as relevant as their dispersal by air currents. Further studies are needed to evaluate the relative importance of dispersal mechanisms (mainly air currents and animal vectors) in different geographical areas.

Many rivers in Central Europe are heavily affected by increased sedimentation due to erosion from agricultural land. High fine sediment loads can clog the interstitial system, increase turbidity, limit light penetration and potentially reduce primary productivity with negative impacts on stream biota such as reduced abundance and diversity. In this study, the effects of different erosion protection measures on instream sedimentation and the communities of fishes, macroinvertebrates and periphyton were evaluated. The erosion protection measures in the catchment successfully reduced the fine-sediment and nutrient input into the river system resulting in positive effects on interstitial habitat quality and the species assemblage of the assessed biota. The single taxonomic groups differed in their response both to catchment-related and instream-related variables. Fish community composition was best explained by catchment-scale variables, while periphyton and macroinvertebrate assemblage structure was significantly governed by instream-scale variables. For increasing restoration success, a combination of measures in the catchment area with structure-enhancing measures within the stream is necessary. The results also suggest that an integrative assessment of abiotic and biotic variables in monitoring increases the detectability of effects on the instream scale.

Organismic drift in lotic waters can have major impact on population dynamics. It is influenced by a variety of interacting abiotic and biotic factors, and species often have evolved specific strategies for drift avoidance and compensation. We studied downstream and upstream movements of larval fire salamanders (Salamandra salamandra) within three first-order streams in Germany using up- and downstream traps. We tested several predictions related to the influence of body size, water flow and inclination on the number of upstream and downstream moving larvae. Larval fire salamanders actively moved upstream in all creeks, however, in much lower numbers than downstream. The total body lengths of upstream and downstream moving larvae did not differ significantly; in contrast, downstream drifting larvae were smaller compared to non-drifting larvae collected randomly from the creeks in-between traps. There was no negative effect of the amount of water flow on larval upward movements, but significantly more larvae drifted downstream with the increasing water flow volume. There was no effect of inclination on the amount of either upstream or downstream movements. Our results indicate that upstream movements are a side product of a principle rheotactic behaviour, which prevents larvae from being drifted downstream.

The complex, stratified seaweeds within kelp forests provide habitat to a multitude of organisms and can alter the physical and chemical parameters of their surrounding environment. It is unclear, however, how patterns in the architecture of these beds change as the tide ebbs and floods. We investigate biomass distribution of floating and stipitate canopies within a kelp bed during low and high slack tides to determine how biomass interacts with common environmental parameters (nutrients, light, and mass-transfer). Floating canopy biomass remained consistent despite differences in depth, likely driven by an interaction between stipe density and individual biomass. Biomass was distributed inconsistently throughout the water column, in which biomass at the surface roughly doubled at low tide relative to high. Despite an increase in kelp biomass at the surface of the water column during low tide, more light reached the benthos than at high tide, suggesting that seawater optical properties independent of algal canopy better explain light attenuation. Seawater nutrients were consistent throughout the bed. Rates of mass-transfer decreased from the exterior to the interior of the bed and also attenuated with depth. This study highlights the structural complexity of kelp beds and the localized effects on important environmental variables.

Reduced impact logging has emerged as one alternative to reduce the effects of timber harvesting. However, the effects of this method on aquatic ecosystems still need to be tested. We studied the effects of logging (reduced-impact logging—RIL and conventional logging methods—CL) on the chemical water quality and physical habitat conditions of streams in eastern Amazonia, as well as on Ephemeroptera diversity. Were analyzed control streams (without logging—CONTROL), streams with RIL and streams with CL, located in the Capim River Basin. Specimens were collected using a dipnet, following a standard protocol and abiotic data were measured with a multiparameter probe. Conventional logging in proximity to streams increased the conductivity and pH of the water, reduced dissolved oxygen and canopy cover of the stream’s channel, altering the composition of Ephemeroptera when compared with CONTROL and RIL areas. We verified that specialist Ephemeroptera species within control environments were replaced by species more tolerant to changes in the natural habitat conditions. In contrast, there was species similarity between RIL and CONTROL streams.

In this article, we report on the development and growth of alpine chironomid species in a highly glaciated headwater, using biometrical analyses. Glacially influenced alpine streams are characterized by year-round harsh environmental conditions. Only a few, highly adapted benthic insects, mainly chironomid larvae (genus Diamesa) live in these extreme conditions. Although several studies have shown patterns in ecosystem structure and function in alpine streams, cause–effect relationships of abiotic components on aquatic insects’ life strategies are still unknown. Sampling was performed at Schlatenbach, a river draining the Schlatenkees (Hohe Tauern NP, Austria), at three sites and on six occasions from August to October 2015. Semi-quantitatively sampled Diamesa cinerella (Meigen 1835) and Diamesa steinboecki (Goetghebuer 1933) larvae were biometrically analysed, and they showed differences in larval size and biovolume with higher values close to the glacier. Considering the decreasing water temperatures but increasing benthic organic matter towards the glacier, food availability seems to play a crucial role for larval size in highly glaciated alpine headwaters. This is the first study to show that harsh conditions in these environments (low temperatures, high turbidity and flow dynamics) may exclude many taxa, but favour other, highly adapted species, when their essential needs (food quality and quantity) are guaranteed.

Explaining the varying success of invaders is a central question in invasion biology. Florida is a good region to test hypotheses related to invasion because of variation in invasion success where a few non-native fishes have established and spread and some have locally established, whereas many have failed to establish despite high propagule pressure. We sampled fish and habitat near ornamental fish aquaculture facilities, sources of propagules, to test hypotheses related to habitat suitability and biotic resistance, resistance either from strongly interacting species or due to diversity (diversity–invasibility). We found a dramatic decline in non-native richness and density with increasing distance from facility effluent (virtually absent > 1,000 m). Non-native and native species richness and density were positively correlated. Increased density and richness of non-natives was associated with higher temperatures and lower abundance of select native species, including predatory largemouth bass Micropterus salmoides, but little support was found for the influence of eastern mosquitofish Gambusia holbrooki. Overall, we found mixed support for the contribution of abiotic and biotic factors and no support for the diversity–invasibility hypothesis. Additional studies into species-specific traits and manipulative experiments will provide key data on the contribution of abiotic and biotic influences on invasion success.

The clam Rangia cuneata, originating from the Gulf of Mexico, was recorded in the Vistula Lagoon for the first time in the early 2010s, and quickly became the dominant component of the zoobenthic biomass. To assess mortality as a factor potentially controlling the growth of Rangia population, a year-long field experiment involving marked bivalves placed in sediment-filled trays deployed on the bottom was conducted in 2014 and 2015. Predator-induced mortality of the clams was low in summer, and very high in the winter–spring period. It was inversely proportional to the size of the clams. Such changes can be partially attributed to predation from at least five fish and three duck species, which contained clams in their digestive tracts. Non-predatory mortality particularly affected large individuals, and was highest in spring, several weeks after the end of winter. We hypothesize that it could be caused by persistent low temperatures over several winter months which led to considerable weakening of the condition of clams. A long winter could also reduce their resistance to environmental stress and potential effect of epibionts, as well as increase susceptibility to predation.

The Southern Ocean is a crucial component of the global climate system and plankton communities inhabiting the Ocean are important in the global carbon cycle. Our paper is aimed to reveal possible factors, which keep identity and explain changes of the community structure at the mesoscale. We tested the absolute values of environmental variables (e.g., temperature, salinity, chlorophyll) as well as the position of the oceanic frontal zones and water masses as these possible factors. We chose the epipelagic zone of the Drake Passage as a unique environment, where gradients of abiotic variables are the most sharp and the boundaries between water masses are not always coincident with the position of fronts: we recorded six water masses and two hydrological fronts. No strict connection between the position of hydrological fronts and absolute values of hydrological variables from one side, and community variables from another, was found. Instead, boundaries between communities coincided with the boundaries between water masses thus indicating greater importance of water mass origin and history and lesser importance of the current hydrological variables.

Understanding patterns in freshwater mussel distributions and habitat use, particularly for imperiled species, is critical for their conservation. To aid in management of imperiled mussels, and to demonstrate the utility using both landscape-based and biotic predictors in assessing species habitat suitability, we modeled 11 imperiled mussels in rivers of Michigan, USA. Models were developed with MaxEnt using a combination of host fish richness, natural abiotic reach variables, and landscape-based natural and anthropogenic variables. Because potential host fishes are important biological determinants of mussel distributions, fluvial host fish distributions (n = 37) were modeled and integrated as a predictor in mussel models. Key predictors determining habitat suitability for mussels included host fish richness, a strong positive predictor for 8 of 11 mussel species, stream discharge, urban land use, and upstream dam density. Models predicted 853 to 10,138 stream km of suitable habitat (1.1 to 13.6% of the state’s stream length) for the 11 mussel species, with 54 to 1,382 km (0.1 to 1.8%) being considered highly suitable habitat. Mapping of suitable habitats identified streams with available habitat for multiple listed species, allowing for more informed decisions in conservation planning and management of Michigan’s listed freshwater mussels and their fish hosts.

Species distributions are determined by abiotic and biotic factors as well as dispersal, but most studies focus exclusively on abiotic (mainly climatic) components. In this study, we evaluated the influence of dispersal as a predictor for species distribution models (SDMs) using the turtle Mesoclemmys tuberculata as an example. We specifically tested whether dispersal is a better predictor of the distribution of M. tuberculata than climatic predictors. We sampled occurrence records of M. tuberculata to build SDMs and used the distance of each cell to the nearest river (river distance) as a predictor for dispersal. In addition, three bioclimatic predictors that quantify temperature and precipitation were used. We applied five different algorithms (BioClim, Domain, Maxent, SVM, and Random Forest) to model the distribution of M. tuberculata and evaluate the relative influence of each predictor variable. Although models including dispersal as a predictor performed slightly better than models omitting it, climatic predictors were found to be more important to describe species distribution across all SDMs. Our results suggest that although dispersal limits the potential geographic areas that the species may reach, abiotic parameters determine where M. tuberculata actually lives. Finally, we used consensus maps to prioritize areas for future field surveys.

15 pages, 4 figures, 5 tables, Properties of the shells and byssus filaments secreted by marine mussels are affected by environmental and biotic factors. In this study, we investigated the effects of pH and temperature on shell and byssus in artificially created monospecific and mixed aggregations of the indigenous mussel Mytilus galloprovincialis and the invasive mussel Xenostrobus securis. The variability in the response of the mussels was mainly explained by species-specific interactions derived from the type of aggregation. In the mixed groups, acidic conditions caused a decrease in byssus strength in M. galloprovincialis, but an increase in byssus strength in X. securis. Increased temperature positively affected shell strength in X. securis, but only in mixed aggregations. Interactive effects of acidification and warming were only detected in the organic matter of shells, the strength of which decreased in M. galloprovincialis in mixed aggregations. Although the invasive mussel may be able to take advantage of changed conditions by enhancing byssal attachment, the effects that acidification has on shells may make this species more vulnerable to some predators. The study findings provide some insight into the responses of protective and attachment structures of mussels to biotic and abiotic stressors, highlighting how species interactions may shape the future of mytilid populations, This study was funded by the Spanish government through the Ministerio de Economía y Competitividad (projects AGL2013-45945-R and CTM2016- 76146-C3-2-R) and the Autonomic government Xunta de Galicia-FEDER (project GRC2013-004

Large rivers in tropical regions can experience strong variations of abiotic factors owing to the occurrence of flood pulses. Both man-made and natural floods can cause pulses with varying intensity and duration. Here, we test the hypothesis that ostracod communities in the pleuston of floating plants are persistent during regular pulses and more variable during extreme floods. Ostracod communities were monitored in the Manezinho Backwater of the Upper Parana River floodplain (Brazil) for 83 months (seven hydrologic cycles). Flood pulses directly influenced the abiotic variables, which in turn were correlated with the species composition and abundance of ostracods. Variability in the species composition differentiated only between the limnophase of cycle 4 (L4: 2009) and the subsequent extreme flood of cycle 5 (P5: 2009–2010). The longer duration and higher intensity of the extreme flood can increase the exchange of organisms through the aquatic connections between the lake and the river and can potentially trigger the hatching of dry-resistant eggs, increasing variability in ostracod species composition. The absence of significant differences in the species composition variability between the other succeeding periods shows that these communities are persistent and buffered to the effects of natural pulses of short durations.

Little is currently known regarding microbial community structure, and the environmental factors influencing it, within the anchialine ecosystem, defined as near-shore, land-locked water bodies with subsurface connections to the ocean and groundwater aquifer. The Hawaiian Archipelago is home to numerous anchialine habitats, with some on the islands of Maui and Hawaii harboring unique, laminated orange cyanobacterial–bacterial crusts that independently assembled in relatively young basalt fields. Here, benthic and water column bacterial and micro-eukaryotic communities from nine anchialine habitats on Oahu, Maui, and Hawaii were surveyed using high-throughput amplicon sequencing of the V6 (Bacteria-specific) and V9 (Eukarya-biased) hypervariable regions of the 16S- and 18S-rDNA genes, respectively. While benthic communities from habitats with cyanobacterial–bacterial crusts were more similar to each other than to ones lacking it on the same island, each habitat had distinct benthic and water column microbial communities. Analyses of the survey data in the context of environmental factors identified salinity, site, aquifer, and watershed as having the highest explanatory power for the observed variation in microbial diversity and community structure, with lesser drivers being annual rainfall, longitude, ammonium, and dissolved organic carbon. Our results epitomize the abiotic and biotic uniqueness characteristic of individual habitats comprising the Hawaiian anchialine ecosystem.

Dormancy, the physiological start of rest, occurs in numerous animal species. Many crustaceans release various types of encased embryos in a state of dormancy (e.g., cysts, ephippia, etc.). These dormant propagules require specific combinations of abiotic environmental cues to terminate dormancy. Our goal was to determine if population-specific responses to varying levels of salinity and light (photoperiod) would be present in dormancy termination of the brine shrimp, Artemia franciscana, from distinct environments. Therefore, we cross-factored different salinity concentrations and photoperiods with three A. franciscana populations collected from geographically distinct environments. To measure population-specific response, hatching success (i.e., hatching percentage) was calculated for each treatment. Our results supported the hypothesis that diverse populations of A. franciscana do have population-specific responses to photoperiod and salinity ranges, which affect hatching success (e.g., a population from Portugal showed the greatest hatching success at a salinity of 50 g/l, while populations from Spain and the U.S.A. exhibited the greatest hatching success at 25 g/l). These population-level differences should be taken into consideration during experimentation, especially when examining hatching success in this model organism.

Cross-ecosystem movements of mobile consumers are a primary mechanism by which energy and nutrients are exchanged between disparate ecosystems. While factors influencing variation in bottom–up subsidies between ecosystems have been well studied, much less is known regarding how biotic and abiotic factors influence the dynamics of mobile consumer-driven connectivity. In a literature survey, we found only 14% of studies examined factors contributing to variation in cross-ecosystem marine foraging by freshwater-adapted consumers. Here, we examine the relationships between abiotic factors and cross-ecosystem movements of a highly mobile freshwater-adapted top predator, Alligator mississippiensis (American alligator). As alligators lack physiological adaptations to survive in marine environments, we predict this linkage would be affected by factors that modify the ability to cope with high salinities. Our results reveal that multiple abiotic factors (e.g., relative humidity, temperature, total precipitation) are key explanatory variables of the duration of cross-ecosystem foraging trips by alligators, and that the absence of salt glands does not preclude them from performing long forays into marine environments. More broadly, our results expand our understanding of mobile consumer-driven ecosystem connectivity at the land–sea interface by demonstrating connectivity is highest when physical stressors are relaxed, and access to and availability of resources are maximized.