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While macroinvertebrate dispersal operates at the individual level, predictions of their dispersal capabilities often rely on indirect proxies rather than direct measurements. To gain insight into the dispersal of individual specimens, it is crucial to mark (label) and capture individuals. Isotopic enrichment with 15N is a non‐invasive method with the potential of labelling large quantities of macroinvertebrates. While the analysis of 15N is widely utilised in food web studies, knowledge on the specific utility of isotopic enrichment with 15N for mass labelling of macroinvertebrate individuals across different taxa and feeding types is limited. Previous studies have focused on single species and feeding types, leaving gaps in our understanding of the broader applicability of this method. Therefore, this study aimed to test and compare isotopic mass enrichment across several macroinvertebrate taxa and feeding types. We released 15NH4Cl at five stream reaches in North‐Rhine Westphalia, Germany, and successfully enriched 12 distinct macroinvertebrate taxa (Crustacea and Insecta). Significant enrichment was achieved in active and passive filter feeders, grazers, shredders and predators, and predominantly showed positive correlations with the enrichment of the taxa's main food sources phytobenthos and particulate organic matter. Enrichment levels rose rapidly and peaked at distances between 50 m and 300 m downstream of the isotopic inlet; significant enrichment occurred up to 2000 m downstream of the isotopic inlet in all feeding types. Macroinvertebrate density estimates on the stream bottom averaged to a total of approximately 3.4 million labelled individuals of the 12 investigated taxa, thus showing the high potential of isotopic (15N) enrichment as a non‐invasive method applicable for mass labelling across different macroinvertebrate feeding types. Hence, isotopic enrichment can greatly assist the analysis of macroinvertebrate dispersal through mark‐and‐recapture experiments, as it allows to measure the movement at the level of individual specimens. [ABSTRACT FROM AUTHOR]

Wastewater treatment plant (WWTP) effluents can be sources of environmental contamination. In this study, we aimed to understand whether effluents of three different WWTPs may have ecological effects in riverine recipient ecosystems. To achieve this, we assessed benthic phytobenthos and macroinvertebrate communities at three different locations relative to the effluent discharge: immediately upstream, immediately downstream and 500-m downstream the effluent discharge. Two approaches were employed: the ecological status classification as defined in the Water Framework Directive (WFD) based on biological indicators; constrained multivariate analysis to disentangle the environmental drivers (physicochemical variables and contaminants, namely metals, polycyclic aromatic hydrocarbons, pharmaceuticals, and personal care products) of ecological changes across the study sites. The results showed inconsistencies between the WFD approach and the multivariate approach, as well as between the responses of macroinvertebrates and diatoms. The WWTP effluents impacted benthic communities in a single case: macroinvertebrates were negatively affected by one of the WWTP effluents, likely by the transported pharmaceuticals (other stressors are essentially homogeneous among sites). Given the findings and the scarcity of consistent evidence on ecological impacts that WWTP effluents may have in recipient ecosystems, further research is needed towards more sustainable regulation and linked environmental protection measures. [ABSTRACT FROM AUTHOR]

Floodplain pans are hydrologically dynamic in nature and characterised by variables such as chlorophyll-a (chl-a), water, and sediment chemistry over their hydroperiods. The present study investigated the spatio–temporal variations in water and sediment physico–chemical, and chlorophyll-a concentration characteristics of six floodplain pans found in the Ramsar declared Makuleke wetlands, Kruger National Park, South Africa. The water and sediment physico–chemical variable values were generally elevated during the high-water period, whereas chlorophyll-a concentrations varied across pans and hydroperiod. Benthic chl-a concentration significantly varied across pans with concentrations ranging from 161 to 1036.2 mg m2. The two-way ANOVA showed significant differences in benthic chl-a concentration among hydroperiods, and no significant differences were observed in pelagic chl-a across pans and hydroperiods. Generally, pelagic and benthic chl-a concentration increased as water and sediment chemistry variables increased. Furthermore, three sediment variables, i.e. pH, calcium, and magnesium, and water conductivity were found to be significant in structuring benthic chlorophyll-a dynamics in pans. However, none of the sediment and water variables had a significant effect on pelagic chl-a. Hydroperiod had a significant effect on influencing chl-a concentration, with high and low water level periods being characterised by low and high chl-a concentration, respectively. The n–MDS results showed strong overlaps in chl-a biomass among the Makuleke floodplain pans across hydroperiods. The increasing chl-a concentration in these floodplain pans due to potential bioturbation effects as a result of large mammals could potentially lead to eutrophication, which in turn could affect the system's primary productivity and aquatic biota. Therefore, it is important to establish a continuous monitoring programme on these pans to inform sound management decisions. [ABSTRACT FROM AUTHOR]

This paper introduces and summarises the main outcomes of the 19th workshop of the International Association for Phytoplankton Taxonomy and Ecology held in Tiszafüred, Hungary, Tisza Balneum Hotel, from 23 to 30 September 2022. The selected theme of the workshop was "Trait-Based Approaches in Micro-Algal Ecology". The discussions presented during the workshop sessions resulted in the 18 articles contained in this Special Issue. There are 6 main thematic aspects developed by the participants: 1. Shape and size: are these traits easy to measure? 2. Spatial scales: when and where to look for microalgae? 3. Climate and extremes of ecological gradients: hot topics of this century. 4. Metaphyton and metaphytic habitats: life beyond plankton and benthos. 5. Microalgae in water management: phycology in practice. 6. Traditional and new methods: perspectives and comments. Trait-based approaches in microalgae ecology, although requiring further investigation and methodological development, represent a valid tool for refining the analysis of environmental variability in aquatic ecosystems. The papers presented in this Special Issue demonstrate that these approaches are extremely useful not only in the study of planktic algae but constitute a thoughtful method for the analysis of benthic and metaphytic microalgae in a wide variety of aquatic ecosystems. [ABSTRACT FROM AUTHOR]

Abstract While macroinvertebrate dispersal operates at the individual level, predictions of their dispersal capabilities often rely on indirect proxies rather than direct measurements. To gain insight into the dispersal of individual specimens, it is crucial to mark (label) and capture individuals. Isotopic enrichment with 15N is a non‐invasive method with the potential of labelling large quantities of macroinvertebrates. While the analysis of 15N is widely utilised in food web studies, knowledge on the specific utility of isotopic enrichment with 15N for mass labelling of macroinvertebrate individuals across different taxa and feeding types is limited. Previous studies have focused on single species and feeding types, leaving gaps in our understanding of the broader applicability of this method. Therefore, this study aimed to test and compare isotopic mass enrichment across several macroinvertebrate taxa and feeding types. We released 15NH4Cl at five stream reaches in North‐Rhine Westphalia, Germany, and successfully enriched 12 distinct macroinvertebrate taxa (Crustacea and Insecta). Significant enrichment was achieved in active and passive filter feeders, grazers, shredders and predators, and predominantly showed positive correlations with the enrichment of the taxa's main food sources phytobenthos and particulate organic matter. Enrichment levels rose rapidly and peaked at distances between 50 m and 300 m downstream of the isotopic inlet; significant enrichment occurred up to 2000 m downstream of the isotopic inlet in all feeding types. Macroinvertebrate density estimates on the stream bottom averaged to a total of approximately 3.4 million labelled individuals of the 12 investigated taxa, thus showing the high potential of isotopic (15N) enrichment as a non‐invasive method applicable for mass labelling across different macroinvertebrate feeding types. Hence, isotopic enrichment can greatly assist the analysis of macroinvertebrate dispersal through mark‐and‐recapture experiments, as it allows to measure the movement at the level of individual specimens.

The Joint Danube Survey (JDS) is a regular transnational survey to monitor the quality of the Danube and its main tributaries, in accordance with the EU Water Framework Directive. During the JDS4 in 2019, conventional methods to monitor selected biological quality elements were complemented with DNA metabarcoding.All together 72 phytobenthos samples were collected along the Danube and its major tributaries within the JDS4, using light microscopy and DNA metabarcoding amplifying a fragment of the rbcL marker gene. The (i) applicability of DNA metabarcoding to identify diatom communities compared to microscopy; (ii) diversity metrics between DNA metabarcoding and microscopy analysis and (iii) the usability of DNA metabarcoding for routine monitoring and assessment of the Danube under future JDS surveys were investigated.Diatom communities resulting from light microscopy and DNA metabarcoding assessments share 26.5% of all taxa which corresponds to 64.3% when considering relative abundances. Discrepancies originate from biases both from metabarcoding, e.g. missing taxa from the reference library, and from microscopy, e.g. overlooking of hardly visible taxa. Microscopy detected more taxa in total but metabarcoding revealed a higher alpha diversity, detecting also very rare taxa in a given sample. Molecular and microscopy based Specific Pollution Sensitivity Index (IPS) values correlated significantly but differences were detected at several sites due to the differences in community composition and the overestimation of large taxa by metabarcoding. Although both methods showed a decreasing trend of IPS along the Danube, the metabarcoding based IPS covered a higher range of quality classes indicating lower values for downstream sites and the tributaries.We suggest that metabarcoding provides a standardisable and efficient tool in biomonitoring, being more distinctive among quality classes than microscopy. Due to the high sequencing depth, it is able to detect a higher diversity on genetic level in a time- and cost-efficient manner that should be implemented in future quality assessment tools. We recommend its use in future biomonitoring surveys, for now, as a complementary method to conventional ones.

The removal of the two dams on the Sélune River since 2019 has led to profound changes in the aquatic ecosystem. Lentic habitats bordered by forest had shifted to new conditions (running water and sparsely vegetated riverbanks) therefore shaping organisms’ assemblies. We studied how the reestablishment of aquatic lotic habitats in interaction with riparian vegetation could mediate the restoration of important ecological functions in the new river. Six stations located along the river continuum were surveyed for 3 years after dam removal: two control stations upstream the former reservoir, three restored stations within the former reservoir, and one control station downstream. We monitored physico-chemical characteristics, phytobenthos biomass and the river’s benthic metabolism, and assessed the functional composition of macroinvertebrate communities. We compared the recorded variables among upstream, downstream and restored sampling stations. We observed a rapid recolonization by invertebrates, but a still low phytobenthic primary production in restored stations. Such a low primary productivity was also reflected in the functional composition of invertebrate communities. Three years after dam removal, there was still a significant time lag between communities recovery and expected ecosystem functioning restoration. We observed a quick colonization by aquatic running-water invertebrate communities of new lotic reaches, but a slower recovery of important ecological functions rates such as those observed in control stations.

Eutrophication impairs lake ecosystems at a global scale. In this context, as benthic microalgae are well-established warnings for a large range of stressors, particularly nutrient enrichment, the Water Framework Directive required the development of diatom-based methods to monitor lake eutrophication. Here, we present the diatom-based index we developed for French lakes, named IBDL (Indice Biologique Diatomées en Lacs). Data were collected in 93 lakes from 2015 to 2020. A challenge arose from the discontinuous pressure gradient of our dataset, especially the low number of nutrient-impacted lakes. To analyze the data we opted for the so-called "Threshold Indicator Taxa ANalysis" method, which makes it possible to determine a list of "alert taxa." We obtained a multimetric index based on specific pressure gradients (Kjeldahl nitrogen, suspended matter, biological oxygen demand, and total phosphorous). Considering the European intercalibration process, the very good correlation between IBDL and the common metric (R2 from 0.52 to 0.87 according to the lake alkalinity type) makes us very confident in our ability to match future IBDL quality thresholds with European standards. The IBDL proved at last to be particularly relevant as it has a twofold interest: an excellent relationship with total phosphorus (R2 from 0.63 to 0.83 according to the lake alkalinity type) and a possible application to any lake metatype. Its complementarity with macrophyte-based indices moreover justifies the use of at least two primary producer components for lake ecological status classification. [ABSTRACT FROM AUTHOR]

Using the electron microscopy, 435 diatom algae from 78 genera of 14 different types of tundra water bodies located in the vicinity of the Lena Delta Wildlife Reserve, north of the Arctic Circle, on the north-facing slope of the Primorsky Ridge (the eastern spur of the Kharaulakh Range of the Verkhoyansk mountain system) were revealed. Among them, 24 taxa of the species rank and 1 taxon of the generic rank are new to the flora of Russia. Most of these species are characteristic of oligotrophic water bodies and watercourses in Europe. Sixty-six of the identified species belonging to 28 genera have been identified to the genus level; most of them belong to the genera Planothidium (7) and Gomphonema (10). [ABSTRACT FROM AUTHOR]

Ombrogenous peat bogs at lower altitudes of the Bohemian Massif occur close to their natural climatic limits in the Northern Hemisphere. They have been significantly affected by peat extraction and severe acidification. Recently, climate change effects, such as decreased snow cover and summer heat waves, have resulted in frequent seasonal desiccation of these habitats, indicating their ongoing transition into a different ecological state. Biomonitoring may provide insight into these rapidly changing ecosystems and identify key habitats for biodiversity conservation. The present study focused on the community structure of desmids, one of the most frequent groups of peatland phytobenthos. In total, 207 sites were sampled from the Ore Mts. (Czech Republic) at the altitude range of 750–850 m a.s.l. A modification of the desmid-based nature conservation value (NCV) index was devised to account for the differences among the observed strongly acidic habitats. In the fragments of ombrogenous bogs, which currently cover less than 3% of the area, several ecologically sensitive taxa, such as Cosmarium sphagnicolum and Staurastrum scabrum, were recorded. These taxa did not occur in other habitat types. In addition, the NCV indices of the bog samples were consistently higher than those of the restored pools created in the disturbed bog areas. However, the highest species richness was recorded in several slightly acidic ponds and sinkholes, which were often located outside the existing protected areas. Thus, we concluded that future conservation strategies should consider the remaining bogs and anthropogenic sites as habitats with relatively high ecological values. [ABSTRACT FROM AUTHOR]

The structure of phytobenthic diatom communities was studied to reveal differences between natural and channelized river sections in Slovenia. As part of the national monitoring of surface waters, samples of phytobenthos were collected at 85 sites throughout the country according to standard protocols. At the same time, basic environmental parameters were also assessed. Trophic (TI) and saprobic (SI) indices were calculated based on diatoms and other algae, while diversity indices and gradient analyses were performed only for the diatom community. The results showed that channelized rivers harbor significantly more diverse benthic diatom communities than natural sections, mainly due to the significantly higher number of motile diatom taxa that are able to take advantage of more nutrient-rich and less-shaded river sections because of their high adaptability. Selected environmental parameters explained 34% of the variability in diatom community structure when taxa were classified into ecological types. The removal of Achnanthidium minutissimum yielded clearer results (24.1%) than the total species matrix (22.6%). Therefore, we suggest excluding this taxon from calculations of TI, SI, or other indices when it is determined as A. minutissimum complex, because A. minutissimum complex was most abundant in both types of reaches in our study and has a wide ecological amplitude, which reduces the indicative power of the diatom community in the evaluation of environmental conditions and ecological status. [ABSTRACT FROM AUTHOR]

Phytobenthos, major primary producers in freshwater, may be periodically exposed to herbicides through runoff, spray drift, and leaching, but experimental work on their response to herbicides is limited. Outdoor flumes were used to measure the recovery of intact phytobenthic biofilms, following a short-term pulse to a glyphosate-based herbicide (GBH) and chlorotoluron (CLT), singly or as a mixture (GBHC). Two days following the removal of the herbicides, significant declines in biomass and rates of areal gross maximum photosynthesis were recorded in GBH and GBHC-treated flumes. Herbicide pulses negatively impacted the biomass of phytobenthos, measured as chlorophyll a, which in turn may have alleviated resource limitation, evidenced by significant increases in biomass-specific rates of gross maximum photosynthesis. After 4.5 days, biomass concentrations were similar in controls and treatments, indicating biofilm recovery in the GBH and GBHC biofilms, though the proportion of green algae relative to diatoms was significantly higher in GBH and GBHC-impacted biofilms. Significant increases were recorded in the Trophic Diatom Index (TDI), indicating benthic diatom development along different trajectories, following the herbicide pulse. Collectively, these results indicate greater insights into herbicide impacts on phytobenthos may be gained by working with the whole phytobenthic community.

Phytobenthos, major primary producers in freshwater, may be periodically exposed to herbicides through runoff, spray drift, and leaching, but experimental work on their response to herbicides is limited. Outdoor flumes were used to measure the recovery of intact phytobenthic biofilms, following a short-term pulse to a glyphosate-based herbicide (GBH) and chlorotoluron (CLT), singly or as a mixture (GBHC). Two days following the removal of the herbicides, significant declines in biomass and rates of areal gross maximum photosynthesis were recorded in GBH and GBHC-treated flumes. Herbicide pulses negatively impacted the biomass of phytobenthos, measured as chlorophyll a, which in turn may have alleviated resource limitation, evidenced by significant increases in biomass-specific rates of gross maximum photosynthesis. After 4.5 days, biomass concentrations were similar in controls and treatments, indicating biofilm recovery in the GBH and GBHC biofilms, though the proportion of green algae relative to diatoms was significantly higher in GBH and GBHC-impacted biofilms. Significant increases were recorded in the Trophic Diatom Index (TDI), indicating benthic diatom development along different trajectories, following the herbicide pulse. Collectively, these results indicate greater insights into herbicide impacts on phytobenthos may be gained by working with the whole phytobenthic community. [ABSTRACT FROM AUTHOR]

Mediterranean lakes present particular challenges when developing ecological assessment techniques, due partly to long histories of human activity in their catchments but also to strong interactions with climate, intensifying in recent decades due to global warming. A survey of diatoms in lakes in Greece revealed both a strong nutrient gradient and a salinity gradient. It is necessary to disentangle these when assessing ecological status in order that appropriate measures for restoring good ecological status are applied. Two approaches were used to develop a Water Framework Directive-compatible metric for assessing ecological status using diatoms. The strongest relationship was obtained using weighted averaging, but an alternative metric, generated by rescaling a well-established and widely used diatom metric performed only slightly less well. The limited number of lakes in Greece resulted in a small dataset, creating a risk of overfitting models and the rescaled metric has the advantage of drawing on a broader autecological knowledge base. Supplementary metrics to evaluate salinity are also proposed in order to ensure that lakes subject to this pressure are clearly differentiated from those where nutrient impacts predominate. Approaches to defining reference conditions and status class boundaries draw on established criteria developed for Water Framework Assessments in Europe to ensure that status assessments in Greece reflect similar levels of ambition to those established elsewhere in the European Union.

Based on the results of monitoring, this paper presents data on the state of eelgrass beds (Zostera Linnaeus) distributed at depths of 5.5–10.5 m (up to 12 m) within the marine coastal waters of the Cape Martyan Nature Reserve (southern coast of Crimea, the Black Sea). In the autumn of 2020, fragments of eelgrass thickets (beds) showed signs of soil erosion, leading to significant exposure of underground roots and rhizomes of sea grasses and the development of abundant epiphyton on them. A specific form of the bottom microrelief was registered for the first time and the location of this bottom relief was associated with distribution of sea vegetation. Numerous micro-depressions in loose deposits at a depth of 10–15 cm were found; they were characterized by a regular rounded shape. The diameters of the micro-depressions were commensurate with the size of the beds, to which they were adjoined strictly on the north-western side. Micro-depressions were filled with temporary accumulations of unattached macroalgae. Further observations revealed the reversibility of this phenomenon. The causes of the microrelief (probably related to increased local hydrodynamics) and the probability of the potential impact of soft soils on the bottom vegetation are discussed. [ABSTRACT FROM AUTHOR]

The species composition of benthic algae changes as water phosphorus concentrations increase, and these changes can be used for ecological status assessment according to the Water Framework Directive. Natural background phosphorus concentrations in rivers and streams that are unaffected by anthropogenic impacts are usually low. Running waters draining catchments with deposits of marine clay, however, may have enhanced phosphorus concentrations, because the clay is naturally rich in apatite. Almost all clay rich areas have been cultivated for centuries, however, and fertilization has increased the soil phosphorus levels. It has, therefore, been difficult to disentangle natural from anthropogenically enhanced phosphorus in streams draining clay rich areas. We compared water phosphorus concentrations, and the Periphyton Index of Trophic Status PIT, between clay and non-clay, impacted and unimpacted rivers in Norway. We found that water phosphorus concentrations and the PIT index were higher in unimpacted clay rivers than in unimpacted non-clay rivers, indicating that natural phosphorus concentrations in clay rivers are indeed enhanced compared to rivers without deposits of marine clay. In addition, phosphate-P contributed 18–23% to total phosphorus in unimpacted clay rivers, but 33–37% in unimpacted and impacted non-clay rivers and clay rivers affected by agriculture. This indicates that the total phosphorus in unimpacted clay rivers is less bioavailable than in non-clay rivers and in impacted clay rivers. Water total phosphorus concentrations in unimpacted clay rivers significantly increased with catchment clay cover. Based on these findings, we derived new status class boundaries for the PIT index in clay rivers. Clay rivers are suggested to be assessed in only two status classes, i.e., “good or better” or “moderate or worse”, respectively. The good/moderate status class boundary for the PIT index was shown to increase with increasing catchment clay cover.

The structure of phytobenthic diatom communities was studied to reveal differences between natural and channelized river sections in Slovenia. As part of the national monitoring of surface waters, samples of phytobenthos were collected at 85 sites throughout the country according to standard protocols. At the same time, basic environmental parameters were also assessed. Trophic (TI) and saprobic (SI) indices were calculated based on diatoms and other algae, while diversity indices and gradient analyses were performed only for the diatom community. The results showed that channelized rivers harbor significantly more diverse benthic diatom communities than natural sections, mainly due to the significantly higher number of motile diatom taxa that are able to take advantage of more nutrient-rich and less-shaded river sections because of their high adaptability. Selected environmental parameters explained 34% of the variability in diatom community structure when taxa were classified into ecological types. The removal of Achnanthidium minutissimum yielded clearer results (24.1%) than the total species matrix (22.6%). Therefore, we suggest excluding this taxon from calculations of TI, SI, or other indices when it is determined as A. minutissimum complex, because A. minutissimum complex was most abundant in both types of reaches in our study and has a wide ecological amplitude, which reduces the indicative power of the diatom community in the evaluation of environmental conditions and ecological status.

Analysis of data on processing samples of macrophytobenthos was used to determine the species richness and composition of Zostera marina and Z. noltei communities in the Taman Bay of the Sea of Azov. The study has shown a weak statistically significant relationship between the degree of dominance of these species and the species richness of communities on an area of 0.25 m2; this relationship can be explained by the "species-energy" theory. If the total biomass of associated species in homogeneous areas was approximately the same, the number of associated species growing in large areas in communities with a high degree of Z. marina and Z. noltei dominance was no less than in small areas with a low degree of Zostera dominance. The similarity (difference) of the species composition of communities with a high and a low degree of Z. marina and Z. noltei dominance was approximately the same. The occurrence of most macroalgal species almost did not depend on the density of Zostera thickets, and an increase in the degree of Zostera dominance could represent a danger only for a few species, such as charophytes Lamprothamnium papulosum and Chara baltica, endemic green algae Ulva maeotica, and the yellow–green algae Vaucheria dichotoma. [ABSTRACT FROM AUTHOR]

A variety of organisms can colonize microplastic surfaces through biofouling processes. Heterotrophic bacteria tend to be the focus of plastisphere research; however, the presence of epiplastic microalgae within the biofilm has been repeatedly documented. Despite the relevance of biofouling in determining the fate and effects of microplastics in aquatic systems, data about this process are still scarce, especially for freshwater ecosystems. Here, our goal was to evaluate the biomass development and species composition of biofilms on different plastic polymers and to investigate whether plastic substrates exert a strong enough selection to drive species sorting, overcoming other niche‐defining factors. We added microplastic pellets of high‐density polyethylene (HDPE), polyethylene terephthalate (PET), and a mix of the two polymers in 15 lentic mesocosms in five different locations of the Iberian Peninsula, and after one month, we evaluated species composition and biomass of microalgae developed on plastic surfaces. Our results, based on 45 samples, showed that colonization of plastic surfaces occurred in a range of lentic ecosystems covering a wide geographical gradient and different environmental conditions (e.g., nutrient concentration, conductivity, macrophyte coverage). We highlighted that total biomass differed based on the polymer considered, with higher biomass developed on PET substrate compared to HDPE. Microplastics supported the growth of a rich and diversified community of microalgae (242 species), with some cosmopolite species. However, we did not observe species‐specificity in the colonization of the different plastic polymers. Local species pool and nutrient concentration rather than polymeric composition seemed to be the determinant factor defying the community diversity. Regardless of specific environmental conditions, we showed that many species could coexist on the surface of relatively small plastic items, highlighting how microplastics may have considerable carrying capacity, with possible consequences on the wider ecological context. [ABSTRACT FROM AUTHOR]

Phytobenthos are often underrepresented in both limnological and paleolimnological studies but may play key roles in whole‐lake production and ecosystem processes including eutrophication, food‐web dynamics, and ecosystem state changes.Photosynthetic pigments, stables isotopes, and diatoms were quantified from surface sediments (0–1 cm) collected across a depth transect of a small, DOC‐rich, mesotrophic lake in boreal northwestern Ontario to assess spatial variation in phytobenthos abundance and production.Maximal concentrations of siliceous algae and cyanobacteria pigments occurred at ~2–6 m depth, with abundant tychoplanktonic diatoms, depleted sedimentary δ13C values, and elevated ratios of precursor chlorophyll a to product pheophytin a, all aligning well with the depths of the thermocline, epilimnetic mixing, and maximum light penetration.These patterns demonstrated the presence of three discrete community assemblages, with greatest mass accumulation occurring at intermediate depths where warm illuminated sediments provide habitat for tychoplanktonic diatoms and cyanobacteria between turbulent shallows and cold and dark depths.If widespread among boreal lakes, this tychoplanktonic zone may exert important effects on whole‐lake production, carbon sequestration, benthic‐pelagic food‐web coupling, eutrophication, and ecosystem state change. [ABSTRACT FROM AUTHOR]

Seaweed valuables have been researched a lot in the last decades but there is a lack of information on brackish seaweed at the eastern part of the Baltic Sea. Previous research shows that Baltic seaweed can be used as a source for phycocolloids as well as for bioenergy. The amount of available usable biomass is not clear, also seaweed in brackish seawater does not reach the dimensions such as the same species in Western parts of the Baltic Sea where the salinity is higher. Therefore, the use of this biomass must be smart to create economic benefit. Three abundant Baltic brackish seaweed species were chosen, to represent green, brown and red seaweed groups and an in-depth information analysis was made to clarify possible focus substances that could be extracted from these species. In this paper we summarize literature of common seaweed components, traditional extraction technology, and potential amount in seaweed and give an overview of novel methods for extraction of seaweed bioactive compounds.

The seaweed Caulerpa cylindracea Sonder is one of the most important invaders on Mediterranean rocky shores. However, many driving pressures affecting its spread are poorly understood and seem to involve the interactions between abiotic and biotic factors. We studied the invasiveness of C. Cylindracea on two shallow vermetid platforms with a con­trasting ecological status on which C. Cylindracea was first detected simultaneously 15 years ago. The cover values of C. Cylindracea and the other macroalgal species were assessed for one year, embracing the whole platform width. Caulerpa cylindracea cover was higher on the platform that had a low ecological status, especially during warmer months at the outer seaward margin. The ecological status of the overstory of native species seems to be a key point conditioning the success of C. Cylindracea invasiveness on these platforms.

We studied three commonly used bioindicator groups: phytoplankton, phytobenthos and benthic invertebrate communities’ structure patterns in transitions between lotic and lentic habitats as consequences of two consecutive large dams constructed in the early twentieth century on the intermediate reach of a lowland river in Normandy (NW, France), the Selune. According to sampling station position along the river, including two in the two reservoir lakes, we defined three sorts of transitions, from upstream to downstream: lentic to lotic transition (hereafter len-lot), lentic to lentic transition (hereafter len-len), within the two reservoir lakes, and lentic to lotic transition (hereafter len-lot).Lot-len transition, imposed by damming, and the recovery of lotic character of the river afterward dams, promoted different diversity patterns for the studied organisms’ groups. Phytobenthos’ α diversity significantly incresed in the len-lot transition, and the highest β diversity score was observed in the lot-len. Both, habitat conditions and spatial controls drove phytobenthos community structure. Benthic invertebrate community was mainly shaped by habitat conditions. Invertebrate’s α diversity significantly changed in the lot-len and len-lot transitions, with the β diversity score being the highest in the lot-len transition. Community’s traits composition of invertebrates best fitted predictions on lotic- and lentic- type communities. Phytoplankton’s α diversity remained unchanged in the transitions and subsequently β diversity scores were low.According to the results, we proposed three classes of organisms based on their response to river damming: i) organisms indifferent or tolerant to dams effect, like phytoplankton communities in this study, that were neither hampered by changes in water flow velocity, and did not display dispersal limitation neither; ii) organisms sensitive to habitat conditions shift but not limited in their dispersal capacity by the dam, like benthic invertebrates and phytobenthos in this study. Benthic invertebrate community and phytobenthos communities differed in their response likely due to their differential dispersal capabilities and niche breadth; iii) organisms limited in their dispersal by the dam, not represented in this study.Riverine organisms best tracked transitions, while β diversity assessment revealed as the most useful metric to disentangle the relative contribution of dispersal limitation or habitat modification provoked by multiple dams.

While macroinvertebrate dispersal operates at the individual level, predictions of their dispersal capabilities often rely on indirect proxies rather than direct measurements. To gain insight into the dispersal of individual specimens, it is crucial to mark (label) and capture individuals. Isotopic enrichment with 15 N is a non-invasive method with the potential of labelling large quantities of macroinvertebrates. While the analysis of 15 N is widely utilised in food web studies, knowledge on the specific utility of isotopic enrichment with 15 N for mass labelling of macroinvertebrate individuals across different taxa and feeding types is limited. Previous studies have focused on single species and feeding types, leaving gaps in our understanding of the broader applicability of this method. Therefore, this study aimed to test and compare isotopic mass enrichment across several macroinvertebrate taxa and feeding types. We released 15 NH 4 Cl at five stream reaches in North-Rhine Westphalia, Germany, and successfully enriched 12 distinct macroinvertebrate taxa (Crustacea and Insecta). Significant enrichment was achieved in active and passive filter feeders, grazers, shredders and predators, and predominantly showed positive correlations with the enrichment of the taxa's main food sources phytobenthos and particulate organic matter. Enrichment levels rose rapidly and peaked at distances between 50 m and 300 m downstream of the isotopic inlet; significant enrichment occurred up to 2000 m downstream of the isotopic inlet in all feeding types. Macroinvertebrate density estimates on the stream bottom averaged to a total of approximately 3.4 million labelled individuals of the 12 investigated taxa, thus showing the high potential of isotopic ( 15 N) enrichment as a non-invasive method applicable for mass labelling across different macroinvertebrate feeding types. Hence, isotopic enrichment can greatly assist the analysis of macroinvertebrate dispersal through mark-and-recapture experiments, as it allows to measure the movement at the level of individual specimens., Competing Interests: The authors declare that they have no competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.)

The aims of this paper were to describe seasonal changes in the qualitative and quantitative composition of diatom taxa and the potential application of benthic diatoms for ecological status evaluation. Diatom indices (IPS and TI) were calculated from data from three different locations along a longitudinal profile of the Bunica, a small karstic river in Bosnia and Herzegovina. A total of 147 taxa were recorded in 12 samples. The most common taxa were Meridion circulare (Greville) C.Agardh and Ulnaria ulna (Nitzsch) Compère. Physical and chemical analyses showed low concentrations of nutrients, good oxygenation, typical pH for carbonate bed/origin and generally oligotrophic conditions and high ecological status. All sites had similar physico-chemical conditions and there were only few seasonal differences. Ordination of the diatom data showed that samples showed neither longitudinal nor seasonal patterns. Median value for IPS (16.8) and for TI (7.3) can be possible "expected" values for ecological status assessment for small karstic rivers in the Mediterranean region. We propose the use of the phytobenthos Intercalibration Common Metric (pICM - an index that combines the IPS and TI) as a national metric for countries developing WFD diatom methods at a late stage. One situation is described, and a solution, which is potentially transferable to other locations in Bosnia and Herzegovina and also to other countries facing similar challenges. [ABSTRACT FROM AUTHOR]

The Kızılırmak River is the longest river (1.355 km) in Turkey and flows into the Black Sea. Main pressures in the basin are waste water discharges, widespread agriculture, livestock activities, and excessive salinity due to the natural formation. In this study, the performance of the most widely used European diatom indices (IPS, IDG, IBD, EPI-D, TDI, and TI) was tested statistically by comparing them with the indicators of organic pollution (biological oxygen demand and ammonium-nitrogen), eutrophication (orthophosphate and nitrate-nitrogen) and salinization (electrical conductivity) in the Kızılırmak basin, Turkey. For this purpose, a total of 97 diatom samples from 33 rivers were collected seasonally in 2014 and 215 species were identified. Principal component analysis was performed to evaluate the "general degradation" in the basin, and linear regression was used to calculate the correlations with diatom indices. As a result, EPI-D, IPS, IBD, and TI were strongly correlated indices, respectively, while IDG and TDI had the lowest correlations with general degradation. Only the EPI-D index was significantly correlated with all environmental variables. Our results showed that the EPI-D index can be used for the ecological status assessment in terms of phytobenthos in the Kızılırmak basin in line with the Water Framework Directive. [ABSTRACT FROM AUTHOR]

In this paper, we report new records of rare diatoms that have recently been found in Southern Poland. Planothidium nanum was found only in the upper reaches of the Centuria River, which is not exposed to human influence, while Navicula flandriae was found in two rivers (the Bolina and the Mleczna) affected by salt mine water from hard coal mines. The impact of anthropogenic salinity on diatom communities is as yet poorly documented. Therefore, we conducted a survey on this phenomenon. We surveyed seven sampling sites for diatom assemblages and habitat characteristics, including three sampling sites impacted by mine water. Navicula flandriae was recorded at both sampling sites affected by salt mine water and in two other rivers (the Centuria and the Mitręga), indicating its wide preference for salinity. We confirmed the occurrence of P. nanum at the same site where this species was found and described in our previous paper. In addition, we recorded the occurrence of this species at two other sites in habitats with similar characteristics (lower reaches of the Centuria and Wiercica rivers). Our results indicate a more common occurrence of N. flandriae and P. nanum, which means that further monitoring of diatoms is necessary. [ABSTRACT FROM AUTHOR]

[Display omitted] • Diatom DNA metabarcoding was implemented in the Joint Danube Survey in 2019. • Communities analysed by different methods share common taxa but contain discrepancies. • IPS obtained by different methods correlate but affected by community discrepancies. • Metabarcoding should be used along morphology-based methods in future campaigns. The Joint Danube Survey (JDS) is a regular transnational survey to monitor the quality of the Danube and its main tributaries, in accordance with the EU Water Framework Directive. During the JDS4 in 2019, conventional methods to monitor selected biological quality elements were complemented with DNA metabarcoding. All together 72 phytobenthos samples were collected along the Danube and its major tributaries within the JDS4, using light microscopy and DNA metabarcoding amplifying a fragment of the rbc L marker gene. The (i) applicability of DNA metabarcoding to identify diatom communities compared to microscopy; (ii) diversity metrics between DNA metabarcoding and microscopy analysis and (iii) the usability of DNA metabarcoding for routine monitoring and assessment of the Danube under future JDS surveys were investigated. Diatom communities resulting from light microscopy and DNA metabarcoding assessments share 26.5% of all taxa which corresponds to 64.3% when considering relative abundances. Discrepancies originate from biases both from metabarcoding, e.g. missing taxa from the reference library, and from microscopy, e.g. overlooking of hardly visible taxa. Microscopy detected more taxa in total but metabarcoding revealed a higher alpha diversity, detecting also very rare taxa in a given sample. Molecular and microscopy based Specific Pollution Sensitivity Index (IPS) values correlated significantly but differences were detected at several sites due to the differences in community composition and the overestimation of large taxa by metabarcoding. Although both methods showed a decreasing trend of IPS along the Danube, the metabarcoding based IPS covered a higher range of quality classes indicating lower values for downstream sites and the tributaries. We suggest that metabarcoding provides a standardisable and efficient tool in biomonitoring, being more distinctive among quality classes than microscopy. Due to the high sequencing depth, it is able to detect a higher diversity on genetic level in a time- and cost-efficient manner that should be implemented in future quality assessment tools. We recommend its use in future biomonitoring surveys, for now, as a complementary method to conventional ones. [ABSTRACT FROM AUTHOR]

Since 2000, after the Water Framework Directive came into force, aquatic ecosystems' bioassessment has acquired immense practical importance for water management. Currently, due to extensive scientific research and monitoring, we have gathered comprehensive hydrobiological databases. The amount of available data increases with each subsequent year of monitoring, and the efficient analysis of these data requires the use of proper mathematical tools. Our study challenges the comparison of the modelling potential between four indices for the ecological status assessment of lakes based on three groups of aquatic organisms, i.e. phytoplankton, phytobenthos and macrophytes. One of the deep learning techniques, artificial neural networks, has been used to predict values of four biological indices based on the limited set of the physicochemical parameters of water. All analyses were conducted separately for lakes with various stratification regimes as they function differently. The best modelling quality in terms of high values of coefficients of determination and low values of the normalised root mean square error was obtained for chlorophyll a followed by phytoplankton multimetric. A lower degree of fit was obtained in the networks for macrophyte index, and the poorest model quality was obtained for phytobenthos index. For all indices, modelling quality for non-stratified lakes was higher than this for stratified lakes, giving a higher percentage of variance explained by the networks and lower values of errors. Sensitivity analysis showed that among physicochemical parameters, water transparency (Secchi disk reading) exhibits the strongest relationship with the ecological status of lakes derived by phytoplankton and macrophytes. At the same time, all input variables indicated a negligible impact on phytobenthos index. In this way, different explanations of the relationship between biological and trophic variables were revealed. [ABSTRACT FROM AUTHOR]

Diatom communities are composed of three distinct water-depth-associated assemblages: a nearshore benthic assemblage, a deep-water benthic assemblage, and a primarily planktonic assemblage. Light attenuation with depth has been hypothesized to be the factor that controls benthic-to-planktonic (B:P) assemblage transitions. Previous studies, however, could not distinguish between the individual effects of light and temperature on diatom assemblage transition because the depth of the B:P transition occurred at or near the depth of the thermocline. This has caused confusion regarding which factor is the more influential variable on benthic-planktonic diatom assemblage transition in surface sediments along water-depth transects in lakes. Two boreal lakes in northeast Ontario were selected to examine this problem. The study lakes are sufficiently deep and clear (Secchi disk depths ~ 9–10 m; dissolved organic carbon ~ 3 mg/L), making it possible to distinguish between the depth of 1% light penetration and the depth of the thermocline. Surface sediment samples were collected along water-depth transects from these lakes to examine intra-lake diatom assemblage structure. In both lakes, the water depth of the diatom assemblage B:P transition was closely associated with the depth of the ~ 1% photosynthetically active radiation value, and was well below the depth of the thermocline, suggesting that light penetration has more influence on this transition than does the thermocline. Because temporal fluxes in nutrients and DOC concentrations can attenuate light, understanding how the light regime influences benthic diatoms in lakes can help inform interpretations of diatom assemblage changes in paleolimnological studies. [ABSTRACT FROM AUTHOR]

Human activities, increasing precipitation, and changes in land run-off deliver a large input of allochthonous nutrients into coastal waters including terrigenous dissolved organic matter (tDOM). Increased subsidies of tDOM into the coastal water are expected to reduce light availability and thus might be one of the factors causing coastal ocean darkening. To investigate the effect of increased tDOM input and thus limitation in light availability on primary production as well as the transfer to higher trophic levels (zooplankton), we conducted a large-scale indoor mesocosm “Planktotrons” experiment with natural (pelagic and benthic) plankton communities from the North Sea. We simulated a coastal ocean system with daily light and tidal cycles for 35 days. The experimental treatments included a light gradient consisting of three levels of tDOM addition (i.e., low tDOM, medium tDOM, and high tDOM) and a control without tDOM addition. Results showed that tDOM addition reduced the light availability by 27% (low tDOM addition), 62% (medium tDOM addition) and 86% (high tDOM addition). Light reduction through tDOM addition negatively influenced phytoplankton biomass during the first half of the experiment (

The present study aimed to detect any changes in concentrations of nutrients and evaluate the impact on the quality of two hemiboreal streams that collect a discharge from two fertilized Scots pine stands. In 2017, nitrogen-containing mineral fertilizer was spread in pine stands on mineral soil located near the first stream. In 2018, potassium containing wood ash was spread in pine stands on organic soil near the second stream. From 2017 to 2020, surveys of physico-chemical parameters, diatoms, macrophytes, and macroinvertebrates were performed to determine the possible effects of fertilization on the ecological quality of the streams. A control site upstream of the fertilized forest stand and a treatment site downstream of the fertilized forest stand was monitored at each stream. Water quality indices, chemical parameters of surface water, and indicator species analysis showed no short-term impact of forest soil improvement with wood ash and ammonium nitrate. We found no clear patterns before and after the fertilization events in both streams, although we did observe inter- and intra-annual differences in aquatic biota and stream ecological quality mainly caused by local environmental factors.

Highlights of new, interesting, and emerging research findings on substratum‐associated microbiota covered from a survey of 2019 literature from primarily freshwaters provide insight into research trends of interest to the Water Environment Federation and others interested in benthic, aquatic environments. Coverage of topics on bottom‐associated or attached algae and cyanobacteria, though not comprehensive, includes new methods, taxa new‐to‐science, nutrient dynamics, auto‐ and heterotrophic interactions, grazers, bioassessment, herbicides and other pollutants, metal contaminants, and nuisance, and bloom‐forming and harmful algae. Coverage of bacteria, also not comprehensive, focuses on the ecology of benthic biofilms and microbial communities, along with the ecology of microbes like Caulobacter crescentus, Rhodobacter, and other freshwater microbial species. Bacterial topics covered also include metagenomics and metatranscriptomics, toxins and pollutants, bacterial pathogens and bacteriophages, and bacterial physiology. Readers may use this literature review to learn about or renew their interest in the recent advances and discoveries regarding substratum‐associated microbiota. Practitioner points: This review of literature from 2019 on substratum‐associated microbiota presents highlights of findings on algae, cyanobacteria, and bacteria from primarily freshwaters.Coverage of algae and cyanobacteria includes findings on new methods, taxa new to science, nutrient dynamics, auto‐ and heterotrophic interactions, grazers, bioassessment, herbicides and other pollutants, metal contaminants, and nuisance, bloom‐forming and harmful algae.Coverage of bacteria includes findings on ecology of benthic biofilms and microbial communities, the ecology of microbes, metagenomics and metatranscriptomics, toxins and pollutants, bacterial pathogens and bacteriophages, and bacterial physiology.Highlights of new, noteworthy and emerging topics build on those from 2018 and will be of relevance to the Water Environment Federation and others interested in benthic, aquatic environments [ABSTRACT FROM AUTHOR]

The present work to study the composition and diversity of phytobenthic communities was conducted at downstream to a 330 MW hydroelectric dam, constructed on River Alaknanda, Uttarakhand. In the present study, a total of 48 genera of phytobenthos belonging to 23 families of 9 orders and 5 classes were recorded. The Chlorophyceae and Bacillariophyceae were the most dominant class respectively. Among the genus, Gomphonema and Navicula were the predominant genera that suggest the organic pollution at downstream to dam. Habitat heterogeneity reflects the increased density, diversity and richness of the phytobenthic communities downstream to dam. [ABSTRACT FROM AUTHOR]

In the coastal ecosystems of the Black Sea, macrophytobenthos and, in particular, the association of Cystoseira crinite, C. barbata, Cladostephus verticillatus, and Corallina mediterranea, with its thick vegetative canopy (VC), is the key contributor to primary production (PP). Though the vertical structure of the canopy, formed by the algal association, is of principal importance to the PP level, this subject has been long-neglected by researchers. The goal of our work was to compare vertical structures of the vegetative canopy of Cystoseira brown algae under diverse hydrodynamical conditions of the Crimean Peninsula coast. Samples were collected using the 50 cm×50 cm counting frame at eight stations positioned in shallow (55–60 cm deep) sites of Sevastopol Bay (Crimean Peninsula). Dry weight biomass of the VC was determined for all algae assemblage and for each algal species individually, per horizontal surface unit, at each height (Z). The study shows that: 1) the VC is characterized by unimodal vertical distribution of biomass, with maximum estimate in the lower part, where the biomass increases to 85% of the total biomass; 2) a series of single-peaked curves reliably describes the unimodal distribution of the biomass; thalli of different age groups are found along the canopy profile; and 3) algae found in epiphytic synusia prefer inhabiting the upper part of the VC. The role of environmental factors (seawater turbulence and solar radiation) is discussed in reference to the formation of the vertical structure, made up of the associations of the brown algae Cystoseira. [ABSTRACT FROM AUTHOR]

The desmid Oocardium stratum is restricted to short sections of active limestone-precipitating springs (LPS) and adjacent headstreams. We studied the succession of photoautotrophic biofilms on artificial substrate at three sites in an LPS stream in spring, summer and autumn. We exposed frosted glass slides between 3 and 12 weeks, and measured calcium carbonate precipitation (CCP), nutrients and environmental parameters. Relative amounts of O. stratum, Bacillariophyceae and Cyanobacteria to overall biomass of the photoautotrophic biofilm were estimated by means of class-specific photosynthetic pigments. Overall, 77% of the photoautotrophic biomass consisted of diatoms, 20% were related to O. stratum and 3% were related to Cyanobacteria. Biomass of O. stratum and diatoms showed a significant correlation with CCP (r = 0.61 and 0.46), while for Cyanobacteria there was no significant correlation. CCP increased exponentially over time and peaked in late summer and late autumn (maximum CCP measured as ash mass was around 10 µg mm−2 week−1). We applied generalised multiple linear regression models (GLM) to evaluate the influence of stream site, weeks of exposure, season and CCP on biofilm development. According to GLM, the biomass of O. stratum was associated with site, exposure time, season and CCP, while the biomass of Cyanobacteria and Bacillariophyceae were not associated with the input variables. The negative standardised beta coefficient of cyanobacterial biomass in the multivariate regression model for the biomass of O. stratum suggest a competition between the two taxa. This likely explains the restricted occurrence of O. stratum within a short section of the active LPS stream. [ABSTRACT FROM AUTHOR]

Climate change threatens surface waters worldwide, especially shallow lakes where one of the expected consequences is a sharp increase in their water temperatures. Phytobenthos is an essential, but still less studied component of aquatic ecosystems, and it would be important to learn more about how global warming will affect this community in shallow lakes. In this research, the effects of different climate change scenarios (SSP2-4.5 and SSP5-8.5, as intermediate and high emission scenarios) on the structure and function of the entire phytobenthos community using species- and trait-based approaches were experimentally investigated in an outdoor mesocosm system. Our results show that the forecasted 3 °C increase in temperature will already exert significant impacts on the benthic algal community by (1) altering its species and (2) trait composition (smaller cell size, lower abundance of colonial and higher of filamentous forms); (3) decreasing Shannon diversity; and (4) enhancing the variability of the community. Higher increase in the temperature (+5 °C) will imply more drastic alterations in freshwater phytobenthos by (1) inducing very high variability in species composition and compositional changes even in phylum level (towards higher abundance of Cyanobacteria and Chlorophyta at the expense of Bacillariophyta); (2) continuing shift in trait composition (benefits for smaller cell volume, filamentous life-forms, non-motile and weakly attached taxa); (3) further reducing the functional diversity; (4) increasing biofilm thickness (1.4 μm/°C) and (5) decreasing maximum quantum yield of photosystem II. In conclusion, already the intermediate emission scenario will predictably induce high risk in biodiversity issues, the high emission scenario will imply drastic impacts on the benthic algae endangering even the function of the ecosystem. [Display omitted] • Climate change threatens shallow lakes, whose phytobenthos is still less studied. • Even a moderate warming (+3 °C) may cause decline in biodiversity of this community. • Worst-case scenario (+5 °C) may result also in loss in its functional properties. • Global warming may favour Cyanobacteria and Chlorophyta at the expense of diatoms. • Global warming may favour small, filamentous, non-motile, weakly attached taxa. [ABSTRACT FROM AUTHOR]

Data about 8 taxa of phytobenthos, firstly recorded for «Mys Martyan» Nature Reserve, are presented: in the supralittoral zone – Planktolyngbya contorta (first record for Crimean Coast and North Black Sea coastal area); in the pseudolittoral and sublittoral zone – Polysiphonia breviarticulata; in the sublittoral zone – Spongomorpha aeruginosa (first record for the hydrobotanical area «Southern Coast of Crimea»), Myriactula rivulariae, Myrionema seriatum, Polysiphonia arenaria, P. subulata, Titanoderma pustulatum (first record for the hydrobotanical area «Southern Coast of Crimea»). Thus, currently 144 species of macrophytes and 67 species of cyanobacteria are listed here. The research was conducted on a stationary monitoring site of «Mys Martyan» Nature Reserve during the spring-summer period of 2017. The obtained results expand the idea of natural phytodiversity of the protected object, the hydrobotanical area and the whole region.

The European Water Framework Directive 2000/60/EC (WFD) has been implemented over the past 20 years, using physicochemical, biological and hydromorphological elements to assess the ecological status of surface waters. Benthic diatoms (i.e., phytobenthos) are one of the most common biological quality elements (BQEs) used in surface water monitoring and are particularly successful in detecting eutrophication, organic pollution and acidification. Herein, we reviewed their implementation in river biomonitoring for the purposes of the WFD, highlighting their advantages and disadvantages over other BQEs, and we discuss recent advances that could be applied in future biomonitoring. Until now, phytobenthos have been intercalibrated by the vast majority (26 out of 28) of EU Member States (MS) in 54% of the total water bodies assessed and was the most commonly used BQE after benthic invertebrates (85% of water bodies), followed by fish (53%), macrophytes (27%) and phytoplankton (4%). To meet the WFD demands, numerous taxonomy-based quality indices have been developed among MS, presenting, however, uncertainties possibly related to species biogeography. Recent development of different types of quality indices (trait-based, DNA sequencing and predictive modeling) could provide more accurate results in biomonitoring, but should be validated and intercalibrated among MS before their wide application in water quality assessments.

The green alga Micrasterias arcuata is commonly found in the periphyton of slightly acidic ponds and wet grasslands of central Brazil. We used M. arcuata complex as a model system for evaluation of the following questions: (a) Is there any relation between morphological characteristics of M. arcuata populations and ecological features of the sites? (b) Can the observed plasticity be explained by an allometric scaling relationship leading to differential distribution of the morphotypes among different habitats (ponds and wet grasslands)? (c) Is there any surface-to-volume ratio (S:V) scaling that can be explained as adaptive response to ecological characteristics of sites? A total of 50 individual semicells of M. arcuata were photographed from ten natural populations, yielding a 500 objects dataset. Individuals from ponds were morphologically different from the ones in the wet grasslands, presenting bigger cells, but also with higher S:V. The eventual surface loss usually associated to bigger sizes was compensated by more elaborated cells, yielding positive allometry of the S:V ratio scaling. Our data support the idea that such differences in cell morphology are an adaptation to environmental conditions, especially desiccation stress favoring cells with lower S:V and higher isoperimetric quotient in the wet grasslands. [ABSTRACT FROM AUTHOR]

Aim: Understanding and quantifying the seasonal patterns in biodiversity of phytobenthos, macro‐zoobenthos and fishes in Mediterranean coastal lagoons, and the species dependence upon environmental factors. Location: The study was carried out in the "Stagnone di Marsala e Saline di Trapani e Paceco," the largest coastal lagoon system in the central Mediterranean Sea (Sicily, Italy), a Special Protection Area located along one of the central ecological corridors joining Africa and Europe. Methods: The coastal lagoon system was selected as a model ecosystem to investigate the seasonal variations in biodiversity indices and dominance–diversity relationships in phytobenthos, macro‐zoobenthos and fishes, and how seasonal variations in temperature, salinity, depth, inorganic and organic suspended matter affect the abundance of the species constituting these communities. Models of ecosystem structure, describing the interactions among functional groups and environmental variables, were also developed using confirmatory path analysis and artificial neural networks to exemplify their application in predicting temperature‐driven alterations. Results: Wide seasonal variations in biodiversity indices and dominance–diversity relationships across the communities of the coastal lagoon system were observed, driven by the dynamics in climate and resource availability. The effects of the environmental variables on taxon abundances varied in relation to the community, with the widest responses elicited in phytobenthos and fishes. Temperature was the main variable affecting taxon abundances in macro‐zoobenthos and was also the major driver of shallow water ecosystem structure. Main conclusions: This research shed light on the seasonal variations in biodiversity of Mediterranean coastal lagoons, elucidating also the tight dependence of phytobenthos, macro‐zoobenthos and fish diversity upon environmental factors. The findings and the methodological approach proposed may be crucial in developing models able to predict future climate‐driven alterations in communities inhabiting these important and threatened ecosystems. [ABSTRACT FROM AUTHOR]

On the basis of our own and published data, the contribution of autotrophic communities to the total primary production in the ecosystem of the Rybinsk Reservoir was estimated during the vegetation season in 2009. The contributions were as follows: 390 198 t C for phytoplankton, 6100 t C for epiphyton, 115 550 t C for macrophytes, and 1491 t C for phytobenthos. Higher aquatic plants constituted 74.4% of the total primary production in the littoral zone of the reservoir, which occupies 4.1% of the reservoir area. [ABSTRACT FROM AUTHOR]