Search

To test if phytobenthic algae provide additional important information to macrophytes and phytoplankton for lake monitoring, we sampled two large lakes in Norway. In each lake, we analyzed water chemistry and phytoplankton above the deepest site, recorded macrophytes and non-diatom phytobenthic algae at 20 sites around the shoreline and estimated site-specific nutrient input from land cover. Since no ready-to-use phytobenthos index exists for lakes in Norway, we tested the PIT index developed for rivers, commonly perceived signs of disturbance such as high algal cover, and taxon richness as well as similarity patterns. Both lakes were nutrient poor, but had potential local nutrient inputs (villages, agriculture). In neither of the lakes did phytobenthos indicate a worse overall ecological status than macrophytes and phytoplankton. Our data therefore, did not suggest that it would be useful to add phytobenthos into surveillance monitoring of lakes in Norway. There was a loose correlation between macrophyte and phytobenthic site-specific taxon richness and similarities. This means that macrophytes and phytobenthos do indeed give partly redundant information. High algal cover was found at sites with both high and low phosphorus input. Using algal cover as indicator of site-specific nutrient input is therefore overly simplistic. Urban and cultivated areas were associated with a more eutrophic PIT. This indicates that the PIT, despite being developed for lotic waters, may be used to detect site specific nutrient input in lakes. [ABSTRACT FROM AUTHOR]

Background - The microscopic world of the freshwater biofilm is a complex association of organisms from prokaryotes to metazoans. Understanding the relationships between these organisms, and between them and their environment, is complicated by the processes by which biofilms are studied. Whilst it is possible to observe and minutely describe the individual organisms which comprise biofilms, interrelationships within the 'community' are often destroyed during sample collection and investigation under the microscope. Ecologists often focus on particular groups of organisms (e.g. diatoms) and interrogate data using multivariate statistics. This offers valuable insights that enable us to understand how associations of particular taxonomic groups respond to key environmental gradients yet offers an essentially abstract view of the microscopic world. Approach - In this essay we contrast the great detail achieved when we see and describe individual cells with the gross approximations necessary when the response of communities is considered. A focus on the diatom assemblage (one part of the intricate biofilm community) and the use of multivariate statistics to interpret responses along ecological gradients offers opportunities to understand environmental change in space and time but at the expense, perhaps, of local detail which may account for some of the unexplained variation in models. We cannot envisage a change in approach in the near future but, instead, encourage a greater awareness of the complexity of stream biofilms to better inform interpretation. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate and compare the intertidal macroalgae community from reef structures subject to different urbanization degrees. Samplings were made in 11 beaches from the Pernambuco coast, northeastern Brazil. The sites were classified according to the level of urbanization into three classes of increasing urbanization pressure: non urbanized (NU), in urbanization process (UP), and consolidated urbanization (UC). Macroalgae were identified in situ non-destructively. A total of 53 taxa were identified, 41 of these were macroalgae. Significant differences were observed in the composition of macroalgae according to the urbanization levels, with Palisada perforata, Gelidiella acerosa, and Caulerpa spp. dominating NU and UP sites, whereas Chondracanthus acicularis, Bryopsis sp., and Ulva spp. dominated UC sites. This work shows that urbanization can have a strong effect on the structure of rocky intertidal macroalgal assemblages and highlights some macroalgae species that can be used as bioindicators for assessing the impact of urbanization on coastal shores. [ABSTRACT FROM AUTHOR]

The availability of quantitative long term datasets on the phytobenthic assemblages of the Mar Piccolo of Taranto (southern Italy, Mediterranean Sea), a lagoon like semi-enclosed coastal basin included in the Italian LTER network, enabled careful analysis of changes occurring in the structure of the community over about thirty years. The total number of taxa differed over the years. Thirteen non-indigenous species in total were found, their number varied over the years, reaching its highest value in 2017. The dominant taxa differed over the years. The number of species in each taxonomic division also varied. In addition to the centuries-old exploitation of its biotic resources, mainly molluscs, the basin has been subject for a long time to a range of anthropogenic driving forces linked to urbanisation, shipbuilding, agriculture and military activities, which have caused chemical and biological pollution, eutrophication and habitat destruction. It may therefore be assumed that these changes were closely related to human activities. Indeed, it was observed that the reduction of only one of these forces, i.e. urban sewage discharge, triggered the recovery of phytobenthos. Therefore, it may be assumed that if the anthropogenic pressure on the Mar Piccolo was eased, it could once again become the paradisiacal place it was held to be in ancient times. [ABSTRACT FROM AUTHOR]

Establishing ecological assessment schemes is challenging when gradients are short and there are no sites with minimal anthropogenic alteration against which metrics can be calibrated. This is the situation for large rivers in Romania and this paper describes efforts to establish meaningful ecological status concepts. The intercalibration exercise, conducted as part of Water Framework Directive (WFD) implementation, has provided a metric ("phytobenthos Intercalibration Common Metric", pICM) which allows ecological status in different countries to be expressed on a common scale. The average boundary positions of countries who participated in this exercise provided a "common view" of status and, together with pICM, offer an "off-the-shelf" solution for countries unable to develop independent methods. However, even when expressed as pICM, Romanian phytobenthos data have a weak relationship with nutrients. Analysis of chemical data and comparison with similar data from elsewhere in Europe confirm that there are few sites with significantly elevated nutrient concentrations. Incorporation of the Romanian data into the larger dataset produced a stronger relationship from which the status of phytobenthos in very large rivers in Romania could be confirmed. This paper shows how the consensus that emerged from the WFD intercalibration exercise supports those countries unable to participate in the initial exercises. [ABSTRACT FROM AUTHOR]

Development of effective metabarcoding-based tools for ecological assessment requires more than just detailed knowledge of ecology and molecular genetics. There is also a need to understand the context within which they will be used, and for the organisation that uses it to understand the techniques involved and, more especially, how the data that are produced differs from that generated by traditional ecological methods. Lessons learnt during the development of a metabarcoding tool for phytobenthos in the UK are set out in this paper. This attempted to develop a molecular "mirror" of the existing light microscopy-based approach to ecological assessment. Although this conservative approach does not exploit the full potential of metabarcoding data, it does mean that benchmarks exist against which performance and data can be judged. However, the pace of developments within molecular ecology means that regulators will need to find ways of incorporating new scientific insights whilst, at the same time, ensuring a stable regulatory regime. Installation of a metabarcoding technique within a regulatory organisation, in other words, is more than a transaction in which one approach is switched for another. A deeper transformation of the organisation is required. [ABSTRACT FROM AUTHOR]

The Sasyk Reservoir is one of the largest seaside reservoirs in Ukraine, artificially maintained as a freshwater area including various floodplain areas. The Reservoir originated from an estuary to now being an almost freshwater reservoir. The diatoms (Bacillariophyta) in benthos were investigated for analyzing the coastal zone diversity of the Black Sea inside the borders of Ukraine. The indicated diatom composition was formed by 97 species (100 infraspecies taxa). Some rare marine and freshwater taxa were noted, as well as three species reported in Ukrainian territory for the first time (Navicula vandamii Schoeman et R.E.M. Archibald, Sellaphora difficillima (Hustedt) C.E. Wetzel, L. Ector et D.G. Mann, and Mastogloia laterostrata Hustedt). The bioindicative characteristics of the diatom composition testified to the freshwater condition of the reservoir. Changes to the salinity level of the Sasyk Reservoir were exposed due to the composition of benthic diatoms. The presence of mesohalobous species (7 taxa) acknowledges conditions that are typical for estuaries and mouths of rivers and reveals the salinity changes in the Sasyk Reservoir. Likewise, the prevailing number of oligohalobous diatoms (61 taxa) reveal presence of freshwater in the reservoir. The implementation of the Polish phytobenthos lake assessment method for the nearby Ukrainian Reservoir was conducted for the first time. The multimetric Diatom Index for lake values varied from 0.39 to 0.76, and revealed alterations in the status over the Sasyk sites, ranging from good, moderate, to poor. Thus, it may be concluded that the current ecological status relating to the composition of benthic diatoms of the reservoir located in the coastal zone of the Black Sea is evaluated as having a moderate status class with some exceptions.

Photoautotrophic biofilms play a pivotal role in self-purification of rivers. We took advantage of the biofilm’s cleaning capacity by applying artificial stream mesocosms, called algae turf scrubberTM (ATS), to reduce the nutrient load of a highly eutrophicated backwater in Vienna (Austria). Since purification strongly depends on benthic algae on the ATS, we focused on the algae community composition and succession. Estimation of coverage, photographic documentation for micromapping, species identification and pigment analyses were carried out. Already one week after exposition, 20–30 different taxa were recorded, suggesting a rapid colonization of the substrate. In total around 200 taxa were identified, mainly belonging to Chlorophyta, Bacillariophyceae and Cyanoprokaryota. Nonmetric multidimensional scaling implied that season and succession strongly influenced species composition on the ATS and a minimum turnover of 0.28 indicates a development towards a more stable community at the end of experiments. We measured maximum biomass production of ~250 g m−2 in June and August and during a period of 5 months nearly 19 kg ha−1 phosphorus could be removed. ATS systems proved to retain nutrients and produce algae biomass in an environmentally friendly and cost effective way and thus support restoration of highly eutrophicated water bodies.

Wrażliwość okrzemek na presje antropogeniczne (np. eutrofizację lub zakwaszenie wód) skutkuje ich szerokim zastosowaniem w bioindykacji. W wielu krajach na świecie podjęto się opracowania lub stosowania opracowanych już indeksów biotycznych opartych na okrzemkach fitobentosowych, służących ocenie stanu wód. Od 2000 roku w krajach członkowskich Unii Europejskiej odbywa się to w ramach wdrażania Ramowej Dyrektywy Wodnej. Wyniki uzyskane przy użyciu polskiej metody oceny jezior na podstawie okrzemek epifitycznych (IOJ - Indeks Okrzemkowy Jezior), znacznie odbiegają od wyników jakie dają pozostałe metody oceny stanu ekologicznego. W niniejszym artykule podjęto się prześledzenia literatury naukowej dotyczącej fitobentosu w bioindykacji w celu zidentyfikowania silnych i słabych stron polskiej metody IOJ oraz wskazania potencjalnych kierunków udoskonalenia metody. Prześledzono literaturę dokumentującą zmienność fitobentosu związaną z jego siedliskiem, zmienność przestrzenną w skali jeziora oraz zmienność w sezonie wegetacyjnym. Przytoczone piśmiennictwo wskazuje na to, że doprecyzowanie wytycznych do procedury poboru prób oraz zwiększenie liczby stanowisk badawczych mogłoby zwiększyć funkcjonalność polskiej metody oceny jezior. Zasugerowano również, że warto podjąć się przetestowania wpływu zmienności sezonowej zespołu fitobentosu na jego wartość bioindykacyjną.

The aim of this work is to simulate the dissolved oxygen deficiency in the coastal zone that sometimes occurs during the summer water stagnation. We consider the main components of the marine ecosystem that play a major role in such processes—concentrations of nitrogen, phosphorus and sulfur compounds in water, dissolved and particular organic matter, oxygen, biomass of phytoplankton and macroalgae. We use the object-based modeling technique to simulate the spatio-temporal variability of the ecosystem in a 2D domain. In comparison with the traditional approach, it gives several advantages: more precise parametrizations of the biological components’ functionality; higher spatial resolution; possibility to account for the individual variability of hydrobionts; easy inclusion of an arbitrary number of species in the model. Our model included three species of phytoplankton and seven macroalgae. Individual-based modules control their functionality. Species of phytoplankton and seaweeds chosen for simulations are typical for the coastal zone of Crimea. In the simulations, we study the contribution of micro- and macroalgae to the processes of self-purification of a semi-enclosed basin in case of a sharp increase in nutrient concentration in water.

Substratum collected during diving surveys of sublittoral communities off the Greek island of Rhodes (Dodecanese, South-East Aegean) in late 2015 was incubated in the laboratory. Among the emerging macroalgal germlings, there was the second-ever record and isolate of the small benthic multicellular alga Schizocladia ischiensis of the poorly known monotypic Schizocladiophyceae, the sister group of the brown algae (Phaeophyceae). Its nuclear ribosomal small subunit, Rubisco spacer (rbcL, psaA, and psbC sequences (in total 5237 bp)) were similar to those of the only previous isolate of the species from Ischia, western Mediterranean. Our new strain formed branched upright thalli attached to the substratum by an amorphous substance secreted at the bottom of the basal cell. It is possible that S. ischiensis is a common member of the infralittoral and circalittoral communities in the Mediterranean and generally overlooked because of its minute size. Germling emergence appears to represent the method of choice to reveal benthic algae of this small size.

Algal turf scrubbers (ATSs) have been used for water remediation in many applications, generating benefits such as water quality improvements and biomass production. Their economical operation is hampered, however, by uncontrolled mixed microbial communities, typical of open cultivation systems that result in lower biomass quality. Design of substratum topography is one approach to control the algal community composition by constraining colonization dynamics. This study seeks to elucidate the role of substratum topography on biomass productivity of benthic algae in an ATS environment. A set of tiles with custom-designed textures of repeated hemispheres across a range of diameters were 3D printed and cast on ceramic clay. An algal turf community dominated by Mougeotia taxa was cultivated on the tiles in a laboratory-scale ATS and harvested for biomass measurements after 21 days. Results show higher biomass on the topographies formed of 500 and 2,000 μm diameter hemispheres, with 74.3% more attached biomass than the 1,000 μm hemisphere and smooth topographies. With the surface area, material roughness at the microscale, and surface chemistry discarded as factors by experimental design, surface topography, especially interstitial space distribution, at the millimeter scale is shown to be a factor in the kinetics of algal cell colonization and growth on surfaces. This study is among the first that specifically focuses on the application of substratum design using additive manufacturing to improving the ATS process. These results can have a significant impact on design of next-generation high-productivity attached growth algae systems. [ABSTRACT FROM AUTHOR]

The study has been motivated by the development of the hydroacoustic techniques for mapping and classifying the benthic habitats and for the research of the microbenthos photosynthesis in the semi-enclosed Baltic Sea, particularly sensitive to human activity. The investigation of the effect of the benthic microalgal photosynthesis on the echo signal from the Baltic sandy sediments is continuing. The study clarifies the impact of the abiotic and biotic factors on the diel variation of the backscattering caused by the benthic microalgal photosynthetic activity. Five multiday laboratory experiments, different in hydrophysical or biological conditions, were conducted. During each measurement series, the “day” (illumination) and “night” (darkness) conditions (L:D cycle) were simulated and the diel variations of the echo energy of the backscattered signal were analyzed. The hydroacoustic data were acquired along with measuring biological and biooptical parameters and oxygen concentration. The study demonstrated the impact of microphytobenthos photosynthesis on the backscattering properties of the marine sediment which is sensitive to the illumination level, benthic microalgal biomass and macrozoobenthos bioturbation. [ABSTRACT FROM AUTHOR]

The structure and seasonal dynamics of marine algal communities dominated by Cystoseira crinita Duby, 1830 were studied in the northeastern Black Sea at depths of 2, 5, and 10 m. Seasonal fluctuations were found to be mainly manifested in biomass changes of the dominant species C. crinita at depths of 2 and 5 m. No seasonal changes in the studied parameters of communities were found at a depth of 10 m. The mean annual production of C. crinita was 1472.3 g/m², with the maximum at a depth of 5 m (2148.1 g/m²). The minimum production was observed at a depth of 10 m. At all depths, the production of C. crinita was highest in the spring; this index had zero values in the fall and winter. [ABSTRACT FROM AUTHOR]

Two methods of quantifying diatoms were compared: (i) by counting valves, and (ii) by simple assignment of individual species to a seven-point scale according to their coverage on a glass slide. The saprobity-trophic index introduced in the Czech Republic for assessing the ecological status of running waters in accordance with the requirements of the Water Framework Directive (WFD) was used for comparison. There were no statistically significant differences between the indices as calculated by the studied methods, and therefore the comparable indicative values of the two approaches were demonstrated. In all cases, however, indices based on coverage classes achieved higher correlation with the fundamental water chemistry parameters than did indices based on diatom valve counts. To explain the cause of higher correlations, different variants of editing input data were used. The results support the assumption that the main cause of the poorer predictive value for the index based on diatom valve counts is that the abundant taxa are attributed too much importance in the final assessment of the environment quality. Using degrees of coverage for the quantification of diatoms in evaluating the ecological status thus appears to be preferable (or at least sufficient) for the given purpose. [ABSTRACT FROM AUTHOR]

Excessive delivery of fine sediments to water bodies has a detrimental impact on the biotic elements used for water body status classification. Although diatoms are typically used to assess stress from eutrophication, as fine sediment has the potential to impact diatoms in many ways, it is not surprising that an index based on benthic diatom assemblages has been proposed: the relative abundance of motile species. This measure is based on the fact that many raphid diatom species are capable of migrating through deposited sediment to avoid negative impacts. However, the use of such an index has yet to be fully tested. Various data analysis techniques were used to explore how indices based on diatom assemblages (related to eutrophication and siltation), diatom species, the traits motility, and nutrient affinity responded to a gradient of percentage cover of fine sediment. Although diatom species showed marked variation in their affinity for percentage cover of fine sediment, the relationship between motility (both percent motile and the trait motility) and deposited fine sediment is not sufficiently strong to be used as a reliable indicator of fine sediment stress. We present an approach, which could potentially be used to develop a new index (diatom indicator of sediment conditions) on the basis of the response of diatoms to fine sediment, but caution that this index requires further development before use. Despite the hydromorphology having considerable potential to affect benthic diatoms, existing indices designed to assess eutrophication were robust to hydromorphological modification, reducing the possibility of false diagnosis of impacts. [ABSTRACT FROM AUTHOR]

The composition and diversity of different water bodies in Kaaba/Bunu Local Government, Kogi State were investigated for both micro and macrobiota. The study covered Oinyi, Odogo and Odonkolo Rivers. Salinity values ranged between 0.03‰ and 0.07‰ indicating the freshwater status of these water bodies, pH was between 6.50 and 7.61. Conductivity values were between 88.1µS/cm and 131.7µS/cm while dissolved oxygen highest value (5.12mg/L) was recorded at Odonkolo River. For the phytobenthos, eighty-five taxa recorded were distributed among five divisions, Bacillariophyta, Chlorophyta, Charophyta, Euglenophyta and Cyanobacteria. Bacillariophyta (Diatoms) accounted for 78.28% of the identified species, followed by the Charophytes, (6.99%), Chlorophytes (5.61%), Euglenophytes (7.43%) and Cyanobacteria (1.69%). Macrobenthic invertebrates recorded three group; gastropoda (37.71%), insecta (28.57%) and oligochaeta (35.71%). [ABSTRACT FROM AUTHOR]

Diatoms are an important part of aquatic biodiversity and the main component of phytobenthos. They play a key role in aquatic ecosystems and indicate water quality. The European Union Water Framework Directive requires that phytobenthos be used for the ecological quality assessment of water. This study evaluated the ecological status of various watercourses in the western Mediterranean basin of Turkey using a multivariate approach and presents a new trophic index Turkey (TIT) based on diatom assemblages. Twenty-five running water bodies were seasonally monitored for biological and physicochemical analyses from summer 2014 to summer 2015. A total of 102 species belonging to 22 genera were recorded. Cymbella excisa Kü tzing, Gomphonella parvula (Kü tzing) Rabenhorst, Ulnaria ulna (Nitzsch) Compè re, and Cocconeis communis f. placentula (Ehrenberg) Chmielevski were the most commonly found species. A canonical correspondence analysis was used to examine the relationship between species and environmental factors. The most effective explanatory factors, including nitrate nitrogen, electrical conductivity, altitude, total nitrogen, orthophosphate, and calcium carbonate significantly influenced the ecological preferences of diatom species in the ecosystems. TIT values ranged between 1.53 in Kaya creek and 2.73 in Dalaman stream (A8). Ecological status of water bodies was assessed using an ecological quality ratio based on trophic index Turkey (EQRTIT) for each of the stations. EQR-TIT ranged from 0.44 in Dalaman stream (A8) to 0.99 in Kocabü k creek during the study period. TIT had a high correlation coefficient (R2=0.77) with log total phosphorus and may be an appropriate diatom metric to assess the ecological status of water bodies. [ABSTRACT FROM AUTHOR]

• A new diatom-based metric for ecological assessment in Mediterranean lakes. • Rescaling algorithm to optimise existing metric for local conditions. • Need to assess nutrients and salinity simultaneously in Mediterranean lakes. • Draw on Water Framework Directive knowledge base to set reference conditions and class boundaries. 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. [ABSTRACT FROM AUTHOR]

Aquatic and riparian habitats increasingly are affected by anthropogenic stressors, but the effects of these stressors on the nutritional quality of primary producers are often unknown. We compared essential fatty acids (EFAs) in the phytobenthos (benthic algae) growing on different substrate types (bricks, clay tiles, rocks, macrophytes, and sediments) at 2 river sites subject to differing anthropogenic stressors (using nutrient concentration as a proxy) in a temperate southern hemisphere location. We hypothesized that the fatty acid (FA) content of phytobenthos changes in response to shifts in local nutrient availability but not substrate type. EFA content (18 : 2ω6, 18 : 3ω3, 20 : 4ω6, 20 : 5ω3, and 22 : 6ω3) in the phytobenthos differed overall among substrates, sites, and seasons and was generally greater in summer than in autumn and winter. EFA content was significantly greater on artificial than natural substrates and was greater at the nutrient-enriched downstream site than at the upstream site. The response of EFA content at the downstream site suggests that land use affected the synthesis of EFAs by phytobenthos and, hence, food quality for aquatic consumers. These findings indicate a potential link between physical factors, such as substrate availability and land management, and the quality of basal food resources available to primary consumers in aquatic food webs. [ABSTRACT FROM AUTHOR]

The aim of the present study was to evaluate the influence of different human activities on water quality and benthos composition in the Ošetnice Stream that is located in the Western Carpathian Mountains. During the whole period of our monitoring, the high concentrations of dissolved oxygen and low content of organic matters were determined. Upstream part of the Ošetnice Stream is affected by long term building activities concerning railway tunnels and by the motorway along the stream that is in winter chemically treated to assure negotiability. Ski area situated close to the stream was used 110 days during the monitored period. Average daily visit was 590 persons. In winter, when road salting was used, concentrations of chlorides, sodium and calcium were noticeably increased in the stream tributaries which had an impact on monitored water parameters. Water quality assessment using macrozoobenthos and phytobenthos indices revealed the environmental state in a range from moderate to good. Decrease of salmonid community in the stream corresponds to start of road use in the year 2002. Salt applied in winter period to ensure road negotiability affected significantly water chemistry of the monitored stream. Deterioration of environmental conditions is mainly due to human activities; nevertheless self-cleaning ability of the stream is high and ensure a fast degradation of pollutants. Thus the biotic communities (except fish) of the Ošetnice Stream have to adapt to changes of the environment within the year.

Recent results of field studies on the exposed coast of Lithuania were used to model the area occupied by the red alga Furcellaria lumbricalis using the Natural Neighbor interpolation technique, while linear regression was applied to estimate the species' standing stock. The area covered by F. lumbricalis extended for 26 km along the coast between depths of 1 and 15 m. The maximum species cover in the study area ranged between 4 and 10 m depth, which is one of the widest in the Baltic Sea. The modelled area of F. lumbricalis covered 35 ± 11 km2 with a total biomass of 7554 ± 3813 t.

Although the Water Framework Directive specifies that macrophytes and phytobenthos should be used for the ecological assessment of lakes and rivers, practice varies widely throughout the EU. Most countries have separate methods for macrophytes and phytobenthos in rivers; however, the situation is very different for lakes. Here, 16 countries do not have dedicated phytobenthos methods, some include filamentous algae within macrophyte survey methods whilst others use diatoms as proxies for phytobenthos. The most widely-cited justification for not having a dedicated phytobenthos method is redundancy, i.e. that macrophyte and phytoplankton assessments alone are sufficient to detect nutrient impacts. Evidence from those European Union Member States that have dedicated phytobenthos methods supports this for high level overviews of lake condition and classification; however, there are a number of situations where phytobenthos may contribute valuable information for the management of lakes. [ABSTRACT FROM AUTHOR]

Copyright of Botanica Serbica is the property of University of Belgrade, Institute of Botany & Botanical Garden Jevremovac and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Benthic diatoms inhabiting littoral zones are regarded as promising bioindicators in lakes. Some pre-standard protocols were proposed and suggested to collect a single site per lake to assess its overall quality. In large lakes, such as Lake Geneva, a spatial heterogeneity of diatom assemblages was suspected, because of differing human pressures. Thirty-five sites were sampled along the shoreline in locations showing various population densities and crossed by rivers flowing into the lake. Different assemblages were found; one corresponded to more oligotrophic areas and was mostly situated on the shoreline next to low population densities; it was mostly composed of low-profile diatoms. A second one corresponded to more eutrophic areas and was mostly situated near densely inhabited areas; it was composed of many high-profile diatoms. A third one was in close vicinity to river inlets, with high abundances of motile diatoms. This last assemblage was spatially restricted to the river plume. After testing several diatom indices, one showed better capacities to assess nutrient level (EPI-L). If we avoid areas near river inlets, the ecological quality assessed with diatom indices ranged from moderate to high ecological status depending on the vicinity situated more or less near densely populated areas. [ABSTRACT FROM AUTHOR]

This study aims to assess the ecological profile of the invasive alga Didymosphenia geminata in NW Spain, analysing the biotic and abiotic factors related to the presence of massive colonies and their effect on river benthos. Physical and chemical parameters were measured in three infested rivers during 2009 and 2010, and biological samples of benthic community were taken according to standard protocols. Collected data was compared with that of control stations located in the same rivers but presenting no evident infestations. The autoecology shown by D. geminata in this study supports former observations reporting the expansion of its ecological niche, with current velocity and nutrients concentrations the environmental variables that best explain the establishment and development of mats in the studied rivers. Regarding its impact, it was observed that the mass growths of this diatom produced a dramatic change in the composition of the algae and macroinvertebrate benthic community which persisted after their disappearance. These results led to the development of a geostatistical predictive model to identify potential risk of dispersion of this diatom in Spanish rivers. The expected distribution of this algae according to this model agreed in general with the actual observed infestations, thus validating it as a tool to prevent and manage future infestations. [ABSTRACT FROM AUTHOR]

A green alga belonging to the genus Prasiola, known from terrestrial, marine and freshwater habitats of polar and cold-temperate regions, is recorded for the first time in the Mediterranean Sea. In 2002, during a survey on soft substrata in the Lagoon of Venice (Italy), specimens referable to this genus were found in several areas. The morphological features of thalli are described and their occurrence in the Lagoon of Venice is discussed. Data on associated algal vegetation are also presented.