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Algal communities act as sensitive indicators of past and present climate effects on northern lakes, but their responses can vary considerably between ecosystems. Functional trait-based approaches may help us better understand the nature of the diverse biotic responses and their underlying ecosystem changes. We explored patterns in diatom (Bacillariophyceae) growth forms and species composition during the Neoglacial in two shallow lakes typical of subarctic regions, including a dark-colored woodland lake and a clear tundra lake. Sediment carbon and nitrogen elemental and isotope biogeochemistry and spectral indices were used to track broadscale changes in lake productivity, the inflow of organic carbon from land, and benthic substratum over the past three millennia. The biogeochemical indices tracked declines in land-lake connectivity as well as lake-water and sediment organic enrichment above and below the subarctic treeline driven by Neoglacial cooling. This broadscale environmental transition was intercepted by periods of elevated primary production associated with transient Neoglacial warm anomalies and, in particular, the twentieth century warming. Although the Neoglacial development of the lakes showed conspicuous similarities, diatom functional and taxonomic responses were not uniform between the lakes pointing to intrinsic differences in the development of benthic habitats and underwater-light regimes. Many of the observed biotic shifts aligned with expectations based on earlier research linking diatom functional traits to changing light and organic levels but the results also point to further research needs, particularly to better differentiate the individual and interactive effects of substratum and light. Despite distinct anthropogenic imprints in the biogeochemical record, the scale of human impact on the lakes’ biota has not, as yet, been profound, but the changes are nonetheless clear when compared to the previous three millennia of natural lake development.

Cold subarctic pond ecosystems will be threatened due to the increase in global temperatures. Therefore, it is important to gain more knowledge on how their biota may respond to global warming. The aim of this research was to illustrate the variability in diatom species richness and community composition along environmental gradients in northernmost Finland and Norway and reveal the variables most strongly associated with diatom biodiversity. We also compared diatom biodiversity among different biotope types and placed emphasis on the distribution of rare diatom taxa. A total of 100 subarctic ponds from the Finnish and Norwegian Lapland covering an elevational gradient of 8-887 m above sea level were sampled. A generalised linear model and hierarchical partitioning were used to identify variables associated with diatom species richness. To identify variables associated with diatom community composition, a non-metric multidimensional scaling ordination was performed. Finally, a principal component analysis and permutational multivariate analysis of variance were used for the investigation of environmental and biotic differences among biotope types. Water pH, aluminium concentration, and air temperature best explained the variation in species richness and community composition. Diatom species richness and community composition did not differ among the biotope types, but environmental variables in pine forests differed significantly from other biotope types. Many diatom species occupied the entire elevational gradient, while rare taxa seemed to appear at the ends of the elevational gradient as well around the mid-elevational zone. We found that elevation was not sufficient to explain the variation in diatom species richness and community composition, but diatom biodiversity was shaped by a variety of local-scale environmental variables, some of which are in turn correlated with elevation. Our findings suggest that local abiotic factors and especially water chemistry are important factors in describing the variability in diatom community composition and species richness in subarctic ponds. It seems that the lowest and the highest elevations provide suitable habitats for rare diatom taxa that have unique environmental preferences but some of the rare taxa were also constrained to mid elevations. Our study provides new insights into the role of local abiotic variables in shaping subarctic mountain pond biodiversity. We urge researchers not only to study elevational gradients per se in mountain areas, but also pay special attention to environmental covariates that may play a notable role in maintaining freshwater biodiversity in the subarctic.

Prosjektleder: Jonas Persson Det ble i 2021/2022 gjennomført biologiske og vannkjemiske undersøkelser i Norddalselva i Møre. Hensikten var å vurdere økologisk tilstand og graden av eutrofipåvirkning, og hvorvidt reguleringen av vassdraget har bidratt til redusert økologisk tilstand. Middelkonsentrasjonene av næringssalter (Tot-P og Tot-N) var lave og viste svært god tilstand ved alle stasjoner. Begroingsalgene viste svært god økologisk tilstand ved samtlige stasjoner med tanke på eutrofiering (PIT-indeksen). Andelen næringskrevende arter var lav, og det ble ikke observert unormalt høy dekningsgrad ved noen av stasjonene. Resultatene fra bunndyrsundersøkelsene viste overlag god tilstand med hensyn til organisk forurensing/eutrofiering (ASPT-indeksen). Dette tyder på lite forurensing av lett nedbrytbart organisk stoff og gode oksygenforhold. Ved stasjon NK4 viste ASPT-indeksen moderat økologisk tilstand, men med en indeks-verdi veldig nær grensen til god tilstand og resultatene er basert på bare én prøvetaking. Den samlede økologiske tilstanden for biologien er god ved NK1, NK2 og NK3, samt moderat ved NK4. Samlet sett fremstår den økologiske tilstanden i Norddalselva som god med hensyn til eutrofiering (næringssaltforurensing) og organisk belastning, med små avvik fra naturtilstanden. Vi finner få tegn på at redusert vannføring som følge av reguleringen har økt konsentrasjonen av forurensing eller næringsstoffer i den grad at det har hatt tydelige negative konsekvenser for begroing eller bunndyr i elva. Tussa Energi AS

Prosjektleder: Maia Røst Kile Dette overvåkingsprogrammet er tredje år av en 4-årig rammeavtale som NIVA har inngått med Vannområde Glomma sør for Øyeren. Målsetningen med undersøkelsen har vært å klassifisere økologisk tilstand i henhold til vannforskriften på 20 utvalgte elve- og bekkelokaliteter på bakgrunn av undersøkelser av begroingsalger og heterotrof begroing. I en totalvurdering av økologisk tilstand ble seks lokaliteter klassifisert til å være i god tilstand i 2022, mens de resterende stasjonene var i moderat eller dårlig tilstand. Vannområde Glomma sør for Øyeren

Understanding of the trait-based ecology of the periphytic algal community has increased in the last decade. However, the relationship between their functional diversity and ecosystem functions, such as primary production, has been speculated on, but yet not proven. Human impacts promote changes in biotic communities leading to a risk of extinction, with consequences for the functioning of aquatic ecosystems. In this study, we unraveled the associations between the taxonomic and functional components of periphytic algal diversity, stream eutrophication, and productivity patterns. Furthermore, we simulated future patterns of species extinction to predict how productivity may change when facing extinction. Primary production and taxonomic and functional diversity of the periphytic algal communities were estimated in five streams across a trophic gradient in the Ave River basin (northwest Portugal). Our results demonstrated that eutrophication led to a unimodal pattern of taxonomic diversity, while functional diversity tended to increase with increasing eutrophication. We found that only functional diversity had a positive association with primary production. The extinction estimations indicated that almost all species found in our study were at high extinction risk. When we spatially scaled our extinction simulations, we found poor-productive streams after the extirpation of a few species. However, at the regional scale, the ecosystem supports the extinction of at least 40% of species before turning into a poor-productive system. Intermediate levels of disturbance are probably beneficial for the diversity of periphytic algal communities, to a certain extent. Moreover, functionally diverse communities were more productive, and the alleged future extinction of species is likely to lead to poor-productive streams if regionally focused conservation initiatives are not implemented. We recommend that, using simulations of functional extinction, it is possible to infer how the loss of these microorganisms could alter ecosystem functioning, to better predict human impacts on aquatic ecosystems., This study was partially funded by CAPES grant number Finance Code 001. This study was supported by the Streameco project, funded by the European Regional Development Fund— Operational Competitiveness Programme (FEDER-POFC-COMPETE) and the Portuguese Foundation for Science and Technology (PTDC/CTA-AMB/31245/2017).

Microbes play a key role in reef dynamics, mediating the competition between scleractinian corals and benthic algae; however, major shifts in bacterial communities among coral species in response to increases in the abundance of algae are not well understood. We investigated the taxonomic composition of coral-associated microbial communities under algae-overgrowth conditions using 16S rRNA gene sequencing. The results showed that non-algal (i.e., healthy) tissue (HH) had lower bacterial abundance and diversity than tissue collected from the coral–algae interface boundary (HA) and areas of algae growth (AA). Specifically, the HA and AA samples had higher relative abundances of Saprospiraceae, Rhodobacteraceae, and Alteromonadaceae. Compared with Platygyra sp. and Montipora sp., the physiological response of Pocillopora sp. was more intense under algae-induced stress based on microbial gene function prediction. Our results indicate that algal pressure can significantly alter the microbial community structure and function of coral ecosystems. Our data thus provide new insight into the relationship between corals and their microbiome under environmental stress.

In open-canopied temperate rivers, periphyton plays a pivotal role by converting dissolved nutrients into food for biota. International research suggests that periphyton is particularly responsive to flow and nutrient alterations and therefore ideally suited to aiding the prediction and monitoring of the effects of altered flow regimes. Given that one of South Africa’s key focus areas for river management has been the provision of flows to sustain aquatic ecosystems, this study aimed to quantify the relative importance of potential environmental drivers of periphyton, particularly flow, under different nutrient conditions in rivers of the south-western Cape. the study focused on two perennial rivers, the Berg and Molenaars rivers. Quantitative monthly samples of periphyton biomass were collected from four sites, representative of different flow and nutrient regimes, over a 21-month sampling period between September 2007 and May 2009. the frequency of flood disturbance over the wet season was found to be the single most important driver of periphyton communities. It accounted for almost 75% of the total variation in periphyton biomass under natural flow and nutrient-poor conditions and it was therefore identified as the primary driver of periphyton communities. Its role was smaller under moderately enriched conditions and accounted for 45% of the total variation. these findings suggest that periphyton in south-western Cape rivers has great potential as a tool for predicting and monitoring the effects of altered flow regimes under different nutrient enrichment regimes. together with some insight into community structure, the next step is to develop periphyton indicators that reflect different aspects of ecosystem integrity, for use in scenario modelling and other management aspects.

Periphyton is a key primary producer in shallow lakes, sensitive to global warming and changes in nutrient balances. Reduced nitrogen availability due to accelerated denitrification at higher temperatures or in response to reduced N loadings aimed to reduce the eutrophication may affect periphyton biomass and composition, to compensate for the low N availability (e.g. promoting N2-fixing). We analysed periphyton responses to N decline in 12 eutrophic shallow lake mesocosms during one year of low N compared to high N, under three temperature scenarios: ambient, A2 IPCC scenario and A2 increased by 50%. We used two submerged macrophytes (Potamogeton crispus and Elodea canadensis) and artificial imitations of these as substrates for periphyton growth. Nitrogen decline increased periphyton biomass and induced compositional changes irrespective of season, plant type, and temperature. Periphyton biomass was negatively associated to phytoplankton and positively to plant complexity. Warmer scenarios negatively affected periphyton exclusively at high N loadings. Low N conditions were associated with lower periphyton taxonomic richness, lower N2-fixing cyanobacteria biovolume and increased biovolume of large-sized chlorophytes and non-N2-fixing cyanobacteria. Our results suggest that low N conditions promoted periphyton due to a more efficient use of nutrients and improved light conditions resulting from lower phytoplankton biomass and contrasting effects of temperature.

Microbial biofilms have received great attention in the last few decades from both aquatic ecologists and biogeomorphologists. Most recently, this has focused on mapping biofilms to understand their spatial distributions and ecosystem services. Such studies often involve the use of satellite imagery, which typically provides large temporal and spatial scales and wide-range spectral information. Although satellites have the advantage of multi- and hyper-spectral sensors, images often have low spatial resolution that limits their use in river studies, where both rivers are narrower and stream processes occur at resolutions smaller than the footprint of satellite sensors. Spatial resolution is sensor quality dependent but also controlled by sensor elevation above the ground. Hence, high resolutions can be achieved either by using a very expensive sensor or by decreasing the distance between the target area and the sensor itself. To date, sensor technology has advanced to a point where multi- or even hyper-spectral cameras can be easily carried out by an Uncrewed Aerial Vehicle (UAV) at unprecedented spatial resolutions. Where such sensors have high spectral resolution, they are often prohibitively expensive, especially as their use in extreme environments such as glacial forefields risks UAV damage. In this paper, we test the performance of visible band ratios in mapping biofilms in an Alpine glacier forefield characterized by a well-developed and heterogeneous stream ecosystem but using a low-cost UAV. The paper shows that low-cost and consumer grade UAVs can be easily deployed in such extreme environments, delivering both quality RGB images for photogrammetric (SfM-MVS) processing and sufficient spectral information for benthic biofilm mapping at high temporal and spatial resolution. RGB cameras are an alternative to expensive multi- or hyper-spectral cameras.Phototrophic biofilms can be detected and mapped through visible band ratios.High-temporal and high-resolution imagery can be collected by consumer-grade UAVs.Biofilm presence is restricted to stable and water-fed terraces in summer. RGB cameras are an alternative to expensive multi- or hyper-spectral cameras. Phototrophic biofilms can be detected and mapped through visible band ratios. High-temporal and high-resolution imagery can be collected by consumer-grade UAVs. Biofilm presence is restricted to stable and water-fed terraces in summer.

In recent years, benthic algae have been increasing in abundance in the littoral zones of oligotrophic lakes, but causality has been hard to assign. We used field and laboratory experiments...

Stream habitat changes affecting primary consumers often indirectly impact secondary consumers such as fishes. Blooms of the benthic algae Didymosphenia geminata (Didymo) are known to affect stream macroinvertebrates, but the potential indirect trophic impacts on fish consumers are poorly understood. In streams of the Kootenai River basin, we quantified the diet, condition, and growth rate of species of trout, char, and sculpin. In 2018, macroinvertebrate taxa composition was different between a stream with Didymo and a stream without, but trout diets, energy demand, and growth rates were similar. Trout abundance was higher in the stream with Didymo, but the amount of drifting invertebrates was higher in the stream without. In 2019, we surveyed 28 streams with a gradient of coverage. Didymo abundance was correlated only with the percentage of aquatic invertebrates in trout diets and was not related to diets of char or sculpin or condition of any species. Thus, we found no evidence for a trophic link between Didymo blooms and the condition or growth of trout, char, or sculpin in mountainous headwater streams.

We present results of revision based on our personal data and reports published from 1889 to 2020 on the red algal species composition from the Commander Islands. The general list includes 150 species. Six species are reported for the first time, including Phymatolithon lamii, Neoabbottiella valentinae, Callophyllis beringensis, Kallymeniopsis verrucosa, Velatocarpus kurilensis, and Mazzaella hemisphaerica. These species are illustrated by photographs of samples collected by us from Bering Island in September 2020. Another 15 red algal species reported from this area by different authors we attributed by us to doubtful and incorrectly identified taxa. The list of valid species is organized similarly to that in our recent paper on flora of the green and brown algae from the Commander Islands [Klochkova et al., 2020]. In the list, we cite papers containing information on species records from this area. For all species, information on their distribution frequency, depth, and some ecological and biological features are provided. It is shown that in contrast to many other regions of the Russian Far East, the Commander Islands are well studied from phycological and floristic aspects. This is due to seasonal and year-round investigations carried out in this region in different time periods, a thorough diving survey on the coastal area and more complete study on microepiphyte species composition, including microscopic red algae.

The Samokovska River, as the most important watercourse of the Kopaonik National Park, has been poorly investigated from algological and water quality aspects. This river is not covered by the monitoring program of the Serbian Environmental Protection Agency routine. Our research performed in October 2018 aimed to present an algal diversity, ecological status assessment, and negative anthropogenic impacts threatening this river. For ecological status assessment purposes, the diatom indices phytobenthos and physico-chemical parameters of water were used. The typology and the problem of reliable assessing of the ecological status were also discussed on the example of the Samokovska River.

In Commander Islands, the peculiar geographic location, hydrology and geomorphology contributed to de-velopment of a very peculiar algal floristic complex. First scientific information on species composition in this region appeared in XIX century. In this revision, we analyzed scientific publications containing algal floristic information from this region and composed list of species recorded during 1889–2020. We provided information about 52 green and 55 brown algal species recorded from the Commander Islands. The infor-mation concerning representatives of Laminariales is discussed in details, as they form basis of the underwa-ter vegetation. Our species list includes citations of references containing records from the Commander Is-lands and brief description of their biological and morphological characteristics. As we noted, in Russian Far East, Commander Islands belong to one of the few regions with highly examined algal flora.

Prosjektleder Maia Røst Kile Dette overvåkingsprogrammet er andre år av en 4-årig rammeavtale som NIVA har inngått med Vannområde Glomma sør for Øyeren. Målsetningen med undersøkelsen har vært å klassifisere økologisk tilstand i henhold til vannforskriften på 18 utvalgte elve- og bekkelokaliteter på bakgrunn av undersøkelser av begroingsalger og heterotrof begroing. I en totalvurdering av økologisk tilstand ble 3 lokaliteter klassifisert til å være i god tilstand i 2021, mens de resterende stasjonene var i moderat eller dårlig tilstand.

The reduction in open-channel flow velocity due to China’s South-to-North Water Diversion Project (SNP) increases the risk of benthic algal community blooms resulting in drinking water safety issues. Consequently, it has attracted attention from all walks of life. However, regulatory measures to mitigate the risk of algal blooms and the main risk-causing factors are unclear. This study simulated the river ecosystem of the SNP channel through water diversion. Simulated gradient-increasing river flow velocity affects environmental factors and benthic algal alterations, and can be used to explore the feasibility of regulating the flow velocity to reduce the risk of algal blooms. We found that the algal biomasses in the velocity environments of 0.211 and 0.418 m/s decreased by 30.19% and 39.88%, respectively. Community structure alterations from diatoms to filamentous green algae were 75.56% and 87.53%, respectively. We observed significant differences in biodiversity, especially in terms of richness and evenness. The α diversity index of a species is influenced by physical and chemical environmental factors (especially flow velocity). Our study revealed that flow velocity is the main factor affecting the growth and outbreak of benthic algae. The risk of algal blooms in open channels can be effectively mitigated by regulating the flow velocity. This provides a theoretical basis for ensuring the water safety of large-scale water conservancy projects.

Intertidal shellfish reefs are prominent ecosystem engineers with a large ecological function on multiple scales; they provide diverse habitats for a biodiverse mix of invertebrates, fish and birds and act as biological power stations on the intertidal flat that increase biodiversity, promote primary production and enrich the food web. This research focuses on testing the function of intertidal shellfish reefs on algae communities in the Wadden Sea, both on the benthic communities of macroalgae that establish on the reefs, and on the diatoms that form the biofilm in the shallow sediment covering the intertidal.The results are based on a mix of ecological field studies and bio-manipulation experiments; by creating small reefs of cockles, mussels and oysters and observing the effect of the different shellfish reefs on seaweed and biofilm composition and distribution. They indicate that intertidal shellfish reefs create areas of high production and biodiversity, not only improving their own physical habitat, but are also promoting self-reinforcing feedbacks. An important contribution of a template for future studies in molecular analysis of benthic diatoms using rbcL gene as the selected genetic marker is presented as well. The best way to manage intertidal shellfish reefs is to make sure they do not go away by protecting them. The presence of facilitation feedbacks means that for successful restoration of shellfish reefs, it is likely needed to recreate ecological interactions; which is more difficult and complicated than just constructing physical structures.

Hace más de 50 años comenzó su andadura el Centro Oceanográfico de A Coruña. Ocurrió en un vetusto local del puerto, y se denominó por aquel entonces como Laboratorio del Noroeste. Durante este medio siglo este centro ha trabajado básicamente en las áreas de la biología pesquera, la acuicultura marina y la oceanografía multidisciplinar, si bien los equipos de investigación han ido evolucionando a lo largo de este tiempo, abriendo o cerrando líneas de trabajo según las circunstancias. A pesar de haber trabajado en todos los océanos del mundo, incluidos el ártico y el antártico, una parte importante de las investigaciones del oceanográfico coruñés siempre han estado centradas en su entorno cercano: el golfo Ártabro. Desde los años ochenta, este centro coruñés monitorea el ambiente pelágico y bentónico de la ría de A Coruña y su plataforma adyacente. Esto supone una valiosísima serie histórica de datos oceanográficos, cuya utilidad quedó de sobra demostrada durante las catástrofes de los petroleros Aegean Sea y Prestige. La idea de crear este libro surgió justo antes del 50 Aniversario del Centro Oceanográfico de A Coruña (1968-2018). Nace con la intención de recopilar y resumir el conocimiento científico en torno a la biodiversidad marina en el ámbito de trabajo más cercano al centro coruñés. Es intención de este libro el servir como publicación de referencia a todo tipo de estudio sobre la biodiversidad y la oceanografía biológica del golfo Ártabro. Para ello nos servimos de la información obtenida directamente del oceanográfico herculino tanto de sus series históricas, como de otros estudios realizados en la zona. Además, la colaboración en materia de pesca de los centros oceanográficos de A Coruña, Vigo, Santander y Gijón permitió aportar a este volumen el capítulo dedicado a las especies desembarcadas por la flota artesanal en la lonja coruñesa. Por otra parte, los especialistas en bentos duro del Centro de Gijón fueron los encargados de elaborar la parte dedicada a este tipo de fauna. Por último, reseñar la inestimable contribución del Grupo de Investigación BioCost de la Universidade da Coruña, auténticos referentes en el conocimiento de la botánica marina de la zona en cuestión.

The decrease in periodic scouring of pulsed flows in regulated rivers can result in algal communities dominated by filamentous algae, not available as food sources for fish and macroinvertebrates. To study the pulsed flow velocity required to scour benthic algae from natural river beds, the removal effects on the algal biomass and resistances of different species were tested in a laboratory flume at different velocities of 0.8, 1.1, 1.4, 1.7, and 2.0 m/s. The removal of total algal biomass showed a significant positive relationship with increasing velocities, which reached 22% at 2.0 m/s. The biomass removal of green algae and diatoms was higher than that of blue–green algae. The flow velocity at 1.4 m/s had a clear removal effect on filamentous algae. The velocity higher than 1.7 m/s caused a significant increase in the removal percentage of total biomass dominated by diatoms and blue–green algae. To reduce the filamentous algae and retain the diatoms and blue–green algae, a range of near bed flow velocity was suggested to be 1.4–1.7 m/s. This range could serve as a reference for required pulsed flow velocity to reduce the growth of excessive or nuisance periphyton.

Wind-induced sediment resuspension in shallow lakes may enhance nutrient availability while reducing light availability for phytoplankton growth, thereby affecting the entire food-web. Lake restoration projects that reduce wind-induced resuspension are expected to enhance trophic transfer efficiencies, thereby improving food-web structure and functioning. Yet, reduced resuspension may also lead to lower nutrient concentrations in the water column, promote benthic algae development, reduce phytoplankton biomass production and thereby reduce secondary production by zooplankton. Lake Markermeer is a shallow delta lake in The Netherlands subject to wind-induced sediment resuspension. Restoration project Marker Wadden consists of newly built islands aiming to reduce sediment resuspension and promote higher trophic levels. Here, we tested the effects of reduced sediment resuspension on phytoplankton biomass build-up, benthic algae development, and zooplankton abundances at different temperatures in a 14-day indoor microcosm experiment. We used Marker Wadden sediment with three resuspension intensities combined with three temperatures, to also test effects of higher temperatures in shallow sheltered waters. Reduced sediment resuspension decreased nutrient concentrations and phytoplankton biomass build-up, while increasing light availability and enhancing benthic algae biomass development. Reduced sediment resuspension furthermore increased zooplankton biomass. Enhanced sediment resuspension and higher temperatures synergistically interacted, maintaining a high level of inorganic suspended solids. Our experimental results are in line with long-term seasonal observations from Lake Markermeer. Our findings demonstrate that for shallow lakes suffering from wind effects, measures such as Marker Wadden aimed at reducing sediment resuspension can be effective in restoring secondary production and supporting higher trophic levels.

Explaining spatiotemporal variability in metacommunities is challenging because conducting empirical studies that link mechanisms across scales is difficult. We developed a stochastic model of epilithic algal succession in streams to better understand the underlying interactions that drive patch dynamics at three levels of spatial hierarchy: patch, channel habitat, and reach. The state of an algal patch is specified by one of nine community types, which are defined by growth form. Ninety‐two empirical data sets of epilithic succession were used to estimate Markov transition probabilities among patch types as functions of inputs for light, nutrients, and current. Two additional probability matrices determine the effects of herbivory and disturbance based on user inputs. Testing model predictions of patch composition against independent empirical data indicated good correspondence based on resemblance metrics. Early in succession, most patches were occupied by prostrate and erect diatoms. These persisted under low light and nutrient conditions. Motile and stalked diatom patches characterized later stages when resources were moderate. Succession proceeded to mostly filamentous green algal patches under high resource levels. Sensitivity simulations indicated light most affected succession. Herbivory and disturbance increased the probability of prostrate diatom patches. We then used the model to examine how changes in abiotic and biotic parameters affect patch dynamics at different scales. Changes in nutrients or light affected patch diversity differently at the habitat vs. reach scale. Interactions with local resource levels within a channel habitat determined its alpha diversity. The proportion of channel habitat types within a reach, and their collective response to changes, determined beta diversity. Patch diversity within channel habitats generated by herbivory followed the predation hypothesis only when nutrients were low. At the reach scale, herbivory always increased patch similarity among channel habitats, lowering beta diversity. Diversity within channel habitats followed the intermediate disturbance hypothesis for a variety of habitats. Effects of disturbance on beta diversity at the reach scale depended on channel habitat heterogeneity. The stability of patches at the reach scale was highest when disturbance created high patch diversity, supporting the insurance hypothesis. The ideas generated can improve stream bioassessment methods and provide insight into mechanisms underlying patch dynamics in other ecosystems.

Ciguatera poisoning (CP) poses a significant threat to ecosystem services and fishery resources in coastal communities. The CP-causative ciguatoxins (CTXs) are produced by benthic dinoflagellates including Gambierdiscus and Fukuyoa spp., and enter reef food webs via grazing on macroalgal substrates. In this study, we report on a 3-year monthly time series in St. Thomas, US Virgin Islands where Gambierdiscus spp. abundance and Caribbean-CTX toxicity in benthic samples were compared to key environmental factors, including temperature, salinity, nutrients, benthic cover, and physical data. We found that peak Gambierdiscus abundance occurred in summer while CTX-specific toxicity peaked in cooler months (February–May) when the mean water temperatures were approximately 26–28 °C. These trends were most evident at deeper offshore sites where macroalgal cover was highest year-round. Other environmental parameters were not correlated with the CTX variability observed over time. The asynchrony between Gambierdiscus spp. abundance and toxicity reflects potential differences in toxin cell quotas among Gambierdiscus species with concomitant variability in their abundances throughout the year. These results have significant implications for monitoring and management of benthic harmful algal blooms and highlights potential seasonal and highly-localized pulses in reef toxin loads that may be transferred to higher trophic levels.

Resumen Se utilizaron comunidades de algas bénticas que crecieron durante cuatro semanas en sustratos artificiales para estudiar la estructura de las comunidades de diatomeas y se midieron los cambios de la diversidad durante nueve (9) muestreos mensuales entre octubre de 2007 y enero de 2009 en un tramo de 50 m en el sector medio del río Tota (Boyacá, Colombia), a 2.540 m de altitud. Se determinaron taxonómicamente las especies de diatomeas de la comunidad béntica, se calcularon los índices de diversidad de Shannon-Wiener [H'] y de Simpson [S] y se evaluaron los cambios durante el muestreo. Así mismo, se midieron las variables hidrológicas y ambientales. La diversidad de especies se incrementó significativamente (p=

Surf zone hydrodynamics influence subsidies (larval settlers and phytoplankton food) to the intertidal zone; subsidies have been observed to be much higher at more dissipative shores compared to re...

This study addressed the occurrence of resource co-limitation of periphytic communities in a tropical black-water lake. We performed a field experiment using nutrient diffusing substrates to create...

Streams are often constructed on reclaimed coal mines to offset stream losses caused by mining disturbance in the Appalachian coalfield of the Eastern USA. Periphyton is an important compon...

There is a strong coupling between benthic and pelagic habitats in shallow aquatic ecosystems. The outcomes of the coupling determine the key characteristics of these systems. The competition between benthic and pelagic algae for light and nutrient is one of the most important ecological processes of benthic-pelagic habitat coupling in shallow freshwater ecosystems when macrophytes are absent. However, the coupling is affected by omnivorous fish. This minireview first focuses on the coupling of benthic-pelagic habitats in shallow aquatic ecosystems in general. Then we review how omnivorous fish affect the benthic-pelagic interactions. Generally, omnivorous fish may increase water nutrient levels, enhance pelagic algae growth, reduce water clarity, and limit the growth of benthic algae, thereby accelerating the eutrophication process in shallow aquatic ecosystems. However, the mechanisms and overall effect differ among different fish species depending on whether their diet is benthic omnivore, plant-based, or animal-based omnivore. In addition, fish size and age also play a role. The proportion of the omnivorous fish biomass tends to increase with increasing human impact, such as fish stocking, eutrophication, and global warming, therefore, the effects of omnivorous fish on aquatic ecosystem are increasing, far-reaching, and deserve continuous attention.

Microphytobenthos (MPB) is composed of unicellular photosynthetic organisms that colonize intertidal sediments within the first millimeters of the photic zone and form biofilms at low tide. In estuaries, this benthic group can represent the main primary producer and deliver several ecosystem services. However, it is not currently used as a bioindicator of water quality, contrary to the widespread use of phytobenthos in freshwater settings. This study assesses the potential of developing MBP metrics to assess water quality in transitional waters using Sentinel-2 (S2) satellite imagery. A Random Forest machine learning classification was used to distinguish different types of intertidal vegetation in 26 French estuaries and bays, in particular MPB and green macroalgae (chlorophytes), using multispectral indices. High accuracy was generally achieved for the identification of MPB when compared with field validation data, for both User’s and Producer’s accuracies, which corresponded to 94% and 84% respectively. Two Earth observation variables were retrieved: the Normalized Difference Vegetation Index (NDVI), a proxy of MPB biomass, and MPB percent cover integrated over the entire intertidal area of the water body. From a total of 918 S2 images from over a full year, 28% were exploitable due to the combined requirements of cloud-free pixels collected during low tide. With its 10 m spatial resolution, S2 was able to map all estuaries. MPB percent cover showed a stronger gradient between estuaries than MPB NDVI. MPB percent cover was also significantly correlated with green macroalgae percent cover, and a group of estuaries characterized by the highest MPB and green macroalgae coverage corresponded to eutrophic sites impacted by intensive farming activities. A multivariate analysis confirmed that MPB percent cover was indeed related to nutrients. It was also related to sediment type which was one of the main factors underlying differences between estuaries. This work is a first step toward a water quality metric using MPB, and several recommendations are proposed to refine this approach. Sentinel-2 imagery, which is publicly available, presents an interesting compromise to map estuarine microphytobenthos in order to assess the ecological status of transitional waters.

Freshwaters face multiple environmental problems including eutrophication, acidification, salinization, and climate-change, all of which can lead to impairment of ecosystem structure and function. Furthermore, these stressors often act in combination. Benthic algal-based assessments to quantify impairment are used in both the EU and US. In this review, we use case studies, experience, and the literature to compare concepts, approaches, and methods between the EU and US to offer an updated picture of benthic algal-based assessments. Both the US and EU are composed of numerous constituent states having considerable flexibility to adopt individual methods. The goal of this work is to synthesize the various approaches that are used across the EU and US. Specifically, we compare and contrast benthic algal assessment performed in response to core legislation – the Water Framework Directive in the EU and the Clean Water Act in the US, with a particular focus on the steps taken to ensure consistency at different stages of the process. This includes consideration of approaches to sampling design and field methods, taxonomic resolution and laboratory harmonization, metric selection and choice of algal groups, assessment of stressors and stressor/response relationships. A number of commonalities emerged during this process, particularly the focus on diatoms over other algal groups. However, there are also a number of key differences, including more widespread use of multimetric indices in the US compared with the EU. Finally, we consider emerging opportunities, including the potential for using metagenomic approaches for bioassessment in the future.

Hace más de 50 años comenzó su andadura el Centro Oceanográfico de A Coruña. Ocurrió en un vetusto local del puerto, y se denominó por aquel entonces como Laboratorio del Noroeste. Durante este medio siglo este centro ha trabajado básicamente en las áreas de la biología pesquera, la acuicultura marina y la oceanografía multidisciplinar, si bien los equipos de investigación han ido evolucionando a lo largo de este tiempo, abriendo o cerrando líneas de trabajo según las circunstancias. A pesar de haber trabajado en todos los océanos del mundo, incluidos el ártico y el antártico, una parte importante de las investigaciones del oceanográfico coruñés siempre han estado centradas en su entorno cercano: el golfo Ártabro. Desde los años ochenta, este centro coruñés monitorea el ambiente pelágico y bentónico de la ría de A Coruña y su plataforma adyacente. Esto supone una valiosísima serie histórica de datos oceanográficos, cuya utilidad quedó de sobra demostrada durante las catástrofes de los petroleros Aegean Sea y Prestige. La idea de crear este libro surgió justo antes del 50 Aniversario del Centro Oceanográfico de A Coruña (1968-2018). Nace con la intención de recopilar y resumir el conocimiento científico en torno a la biodiversidad marina en el ámbito de trabajo más cercano al centro coruñés. Es intención de este libro el servir como publicación de referencia a todo tipo de estudio sobre la biodiversidad y la oceanografía biológica del golfo Ártabro. Para ello nos servimos de la información obtenida directamente del oceanográfico herculino tanto de sus series históricas, como de otros estudios realizados en la zona. Además, la colaboración en materia de pesca de los centros oceanográficos de A Coruña, Vigo, Santander y Gijón permitió aportar a este volumen el capítulo dedicado a las especies desembarcadas por la flota artesanal en la lonja coruñesa. Por otra parte, los especialistas en bentos duro del Centro de Gijón fueron los encargados de elaborar la parte dedicada a este tipo de fauna. Por último, reseñar la inestimable contribución del Grupo de Investigación BioCost de la Universidade da Coruña, auténticos referentes en el conocimiento de la botánica marina de la zona en cuestión.

Prosjektleder Maia Røst Kile Dette overvåkingsprogrammet er første år av en 4-årig rammeavtale som NIVA har inngått med Vannområde Glomma sør for Øyeren. Målsetningen med undersøkelsen har vært å klassifisere økologisk tilstand i henhold til vannforskriften på 25 utvalgte elve- og bekkelokaliteter på bakgrunn av undersøkelser av begroingsalger og heterotrof begroing. I en totalvurdering av økologisk tilstand ble 3 lokaliteter klassifisert til å være i god tilstand i 2020, mens de resterende stasjonene var i moderat eller dårlig tilstand.

Oceanic islands are natural laboratories for investigating species diversity and richness patterns. Changes in abiotic parameters may induce shifts in marine biota. Seaweeds are recognized as bioindicators, though those from remote tropical islands have been rarely studied. This study updates the diversity, richness and distribution of macroalgae from Trindade, a Brazilian volcanic island located 1140 km off the coast. Biotic data, obtained in a global database and in situ and compiled in a new records list, were associated with abiotic parameters. Conservation and ecological issues were discussed in the context of the observed greater richness, expansion of the distributional range and low endemism. A total of 141 species were identified, including 60 new records and 20 taxa of filamentous cyanobacteria. The greater richness, including potential cryptogenic species, may primarily be associated with past incomplete samplings, current new techniques and combined taxonomical methods, including molecular analysis for cryptic species. However, on the macroscale, this study provides information for the re-evaluation of aspects of endemism, connections and biogeographical distribution shifts of seaweed as­semblages, considering environmental changes. In addition, this updated checklist establishes a baseline for further compara­tive studies, reinforcing the hypothesis that biogeographical isolation can be disrupted by meteorological and oceanographic shifts, altering dispersal patterns and resulting in higher ecosystems connectivity., Las islas oceánicas son laboratorios naturales para investigar la diversidad de especies y los patrones de riqueza. Los cambios en los parámetros abióticos pueden inducir cambios en la biota marina. Las algas son reconocidas como bioindicadores, aunque rara vez se han estudiado las de las islas tropicales remotas. Este estudio actualiza la diversidad, riqueza y distribución de macroalgas de Trindade, una isla volcánica brasileña ubicada a 1140 km de la costa. Los datos bióticos, obtenidos en una base de datos global e in situ, compilados en una nueva lista de registros, se asociaron con parámetros abióticos. Los temas ecológicos y de conservación se discutieron en el contexto de la mayor riqueza observada, la expansión del rango de distribución y el bajo endemismo. Se identificaron un total de 141 especies, incluidos 60 nuevos registros y 20 taxones de cianobacterias filamentosas. La mayor riqueza, incluidas las especies criptogénicas potenciales, puede estar asociada principalmente con muestreos incompletos del pasado, nuevas técnicas actuales y métodos taxonómicos combinados, incluido el análisis molecular de especies crípticas. Sin embargo, en la macroescala, este estudio proporciona información para la reevaluación de aspectos de endemismo, conexiones y cambios en la distribución biogeográfica de los conjuntos de algas marinas, considerando los cambios ambientales. Además, esta lista de verificación actualizada establece una línea de base para futuros estudios comparativos, lo que refuerza la hipótesis de que el aislamiento biogeográfico puede verse afectado por cambios meteorológicos y oceanográficos, alterando los patrones de dispersión y dando como resultado una mayor conectividad de los ecosistemas.

Widespread increases in dissolved organic matter (DOM) concentration across northern lakes can alter rates of primary production by increasing nutrient availability and decreasing light availability. These dual effects of DOM generate a unimodal relationship in pelagic primary production and primary producer biomass among lakes over a gradient of DOM concentration. However, the responses of benthic algae to variation in DOM loading are less clear because of their potential to access sediment nutrients. We tested algal production and nutrient limitation along a DOM gradient in northern Sweden. Without added nutrients, benthic algal production showed a unimodal relationship with DOM, similar to reported pelagic responses. Nutrient addition revealed widespread nitrogen limitation, with decreasing severity in lakes with higher DOM. Because the majority of northern Swedish lakes currently fall below the inflection point in this unimodal relationship, moderate increases in DOM have the potential to increase benthic primary production, particularly for epilithic algae.

Prosjektleder Maia Røst Kile Dette overvåkingsprogrammet er siste år av en 4-årig rammeavtale som NIVA har inngått med Vannområde Glomma sør for Øyeren. Målsetningen med undersøkelsen har vært å klassifisere økologisk tilstand i henhold til vannforskriften på 27 utvalgte elve- og bekkelokaliteter på bakgrunn av undersøkelser av begroingsalger og heterotrof begroing. I en totalvurdering av økologisk tilstand ble 4 lokaliteter klassifisert til å være i god tilstand i 2019, mens de resterende stasjonene var i moderat eller dårlig tilstand. Vannområde Glomma sør for Øyeren

We analyzed the abundance of benthic algae in nine forested headwater watersheds in south-central Chile to study the relationship between the variability of the abundance of benthic algae and physicochemical parameters and forest cover factors. Between 10 November 2015 and 18 August 2016, we sampled benthic algae and physicochemical parameters in the streams and characterized forest cover factors in each of the study watersheds. We found that physicochemical parameters and forest cover factors have contrasting effects on abundance. More specifically, the following observations were made: (1) maximum diversity and abundance occurred in watersheds covered with Pinus radiata, (2) seasonal ranks did not influence the abundance of benthic algae, (3) benthic algae abundance is controlled by rank dissimilarities in type of vegetation, solar radiation, volume, density age, canopy openness, native forest area, plantation area and harvested area, and (4) regression analysis of genera exhibited significant variability with physicochemical parameters (water temperature, pH, ammonium, nitrate, phosphorus, solar radiation) and forest cover factors (volume, density, age, native forest area, plantation area and harvested area); however, these effects were not seen in all genera. Factors related to the benthic algae compartment showed the highest sensitivity to forest cover, emphasizing their value as biological indicators of water quality and stream ecological integrity.

Although rivers are of immense practical, aesthetic, and recreational value, these aquatic habitats are particularly sensitive to environmental changes. Increasingly, changes in streamflow and water quality are resulting in blooms of bottom-attached (benthic) algae, also known as periphyton, which have become widespread in many water bodies of US national parks. Because these blooms degrade visitor experiences and threaten human and ecosystem health, improved methods of characterizing benthic algae are needed. This study evaluated the potential utility of remote sensing techniques for mapping variations in algal density in shallow, clear-flowing rivers. As part of an initial proof-of-concept investigation, field measurements of water depth and percent cover of benthic algae were collected from two reaches of the Buffalo National River along with aerial photographs and multispectral satellite images. Applying a band ratio algorithm to these data yielded reliable depth estimates, although a shallow bias and moderate level of precision were observed. Spectral distinctions among algal percent cover values ranging from 0 to 100% were subtle and became only slightly more pronounced when the data were aggregated to four ordinal levels. A bagged trees machine learning model trained using the original spectral bands and image-derived depth estimates as predictor variables was used to produce classified maps of algal density. The spatial and temporal patterns depicted in these maps were reasonable but overall classification accuracies were modest, up to 64.6%, due to a lack of spectral detail. To further advance remote sensing of benthic algae and other periphyton, future studies could adopt hyperspectral approaches and more quantitative, continuous metrics such as biomass.

An updated checklist of the benthic marine algae (seaweeds) of the Northern Arabian Sea coast of the Sultanate of Oman is presented, with a total of 402 taxa, consisting of 75 taxa of brown algae (Phaeophyceae), 238 taxa of red algae (Rhodophyta), and 89 taxa of green algae (Chlorophyta). Obsolete names and taxonomic synonyms as well as information on mis-identified names are provided. The classification in many instances reflects new ideas derived from the results of molecular-based phylogenetics. A total of 18 taxa of benthic marine algae are newly reported for Oman.

Lake Baikal, one of the world’s largest and most biologically diverse lakes, has recently begun to experience uncharacteristic nuisance blooms of filamentous benthic algae. To contribute to...

Benthic algae are the nutritional base of most freshwater food webs. Here we consider the nutritional contribution of benthic algae in the form of fatty acids (FAs) over multiple seasons an...

Se estudió el proceso de retención de fosfato en ríos de regiones subtropicales y templadas. Nuestra hipótesis fue que la retención difiere en las dos regiones. Esperamos más retención en la región subtropical que en la templada. Confirmado esto; las diferencias podrían deberse a una interacción entre la concentración de fosfato y la biomasa de algas, asociada a las diferencias de temperatura. La retención de fosfato se estudió realizando adiciones en continuo de P. La tasa de asimilación (U) y la velocidad de asimilación (Vf: 2.67 E-04 y 9.27 E-05 m/s para los ríos subtropicales y templados respectivamente) fueron asociadas con la concentración basal de fósforo, la biomasa de macrófitas y la zona de almacenamiento transitorio de acuerdo con un análisis de PCA. Así, los ríos de las regiones templadas responden más a la biomasa de las macrófitas que los ríos de las regiones subtropicales que se asociaron principalmente a las algas bentónicas. Estos resultados son novedosos para América del Sur y reflejan la importancia de la biomasa y producción de algas bentónicas o macrófitas en relación con la tasa de captación de P en diferentes ambientes. Phosphate retention processes in streams of a subtropical and a temperate region were studied. Our hypothesis was that retention differs in the two regions. We expect more retention in the subtropical region than in the temperate one. If that were confirmed the differences in stream phosphate uptake may be driven by an interaction between phosphate concentration and algal biomass, associated with differences in temperature. Phosphate retention was studied by carrying out constant rate additions. Nutrient uptake rate (U) and mass transfer coefficient (Vf: 2.67 E-04 y 9.27 E-05 m/s to subtropical streams and temperate one respective-ly) were associated with background phosphate, macrophyte biomass and transient zone storage according to PCA analysis. Thus, streams of temperate regions respond more to macrophyte biomass than streams of subtropical regions which were associated principally to benthic algae. These results are novel for South America and they reflect the relative importance of benthic algal or macrophyte biomass and production in relation to the P uptake rate at the different environments. Fil: Gultemirian, Maria de Lourdes. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Biodiversidad Neotropical. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Biodiversidad Neotropical. Instituto de Biodiversidad Neotropical; Argentina Fil: Giorgi, Adonis David Nazareno. Universidad Nacional de Luján. Instituto de Ecología y Desarrollo Sustentable. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Ecología y Desarrollo Sustentable; Argentina Fil: Feijoó, Claudia Silvina. Universidad Nacional de Luján. Instituto de Ecología y Desarrollo Sustentable. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Ecología y Desarrollo Sustentable; Argentina Fil: Rodríguez Castro, María Carolina. Universidad Nacional de Luján. Instituto de Ecología y Desarrollo Sustentable. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Ecología y Desarrollo Sustentable; Argentina Fil: Fernandez, Hugo Rafael. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Biodiversidad Neotropical. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Biodiversidad Neotropical. Instituto de Biodiversidad Neotropical; Argentina

Australia is a big country. Its land area of 7.7 million km2 is about the same as that of the contiguous 48 United States, but its population (25 million as of exactly 11 pm on 7 August 2018) is le...

Nuisance growth of the alga Cladophora has been a critical issue in the Laurentian Great Lakes for decades. Although loading of total phosphorus (TP) has been below target values since the 1990s, the nearshore of the lakes still experience Cladophora blooms. This study explores the effects of TP loading temporal pattern on Cladophora growth in Rochester Embayment in Lake Ontario, where Cladophora blooms are frequently observed. Long-term TP loadings from the Genesee River, which is the primary tributary to the embayment, are calculated with a hydrological model, and Cladophora indicators based on beach closures and satellite data are collected for 2008–2017 to analyze the TP loading temporal patterns and their relation with Cladophora abundance. Using time series clustering for both TP loading and Cladophora indicators, it is found that besides total annual TP loading, the timing of high TP loading also plays an important role for Cladophora growth. High TP loading in mid-March to mid-June, compared to that in January to mid-March, is found to produce higher Cladophora abundance in summer. This finding is supported and explained using an integrated hydrodynamic and ecological modeling framework that includes a state-of-the-art Cladophora module. This study suggests that future Cladophora control should consider not only the total annual TP loading mass, but also the temporal loading patterns.

The present work included a study of benthic algae on two substrates: rocks and clay on a section of the Tigris River at the Al-Atifiyah site in the fall of 2018. The result of this study was recorded 89 species belong to 50 genus of benthic algae on both substrates and composed of Bacillariophyceae (59.6%, 61.2%), Chlorophyceae (25.8%, 20.4%) and Cyanophyceae (14.5%, 18.3%) respectively on epilithic and epipelic algae. The present study was recorded the highest total algae cell density (1173.2 cells *103/cm2) on epilithic algae while the lowest total algae cell density was recorded on epipelic algae (76.95 cells *103/gm). For measure diversity, four indices of diversity are used: Margalef index, Shannon and Weaver Index, Evenness Index and Simpsons Index. The study showed that benthic algal communities are of high diversity with different distribution and spread of adherent algae on different natural surfaces in the aquatic environment. 62 species of epilithic algae were recorded belonging to 39 genus, while epipelic algae were recorded 49 species belonging to 34 genus. Bacillariophyceae was recorded the highest number of species compared with other classes of benthic algae (59.6%, 61.2%) respectively on epilithic and epipelic Chlorophyceae recorded second ordered after diatoms in importance 25.8%, 20.4%, Cyanophyceae recorded third orders 14.5%, 18.3% respectively on epilithic and epipelic algae.