Freshwater Biology and Limnology

Science popularization paper briefly introducing the diatom identification volume: Freshwater Benthic Diatoms of Central Europe (FBDCE): Over 800 Common Species Used in Ecological Assessment. M. Cantonati, M.G. Kelly & H. Lange-Bertalot (Eds.): 942 pp. Koeltz Botanical Books (ISBN 978-3-946583-06-6). English edition with updated taxonomy and added species of: Hofmann G., Werum M. & Lange-Bertalot H. 2013. Diatomeen im Süßwasser-Benthos von Mitteleuropa. Bestimmungsflora Kieselalgen für die ökologische Praxis. Über 700 der häufigsten Arten und ihre Ökologie. Lange-Bertalot, H. (Ed.): 908 pp. 2. korrigierte Aufl. Koeltz Botanical Books.
The principal goal of this volume is to provide an effective tool for diatom identification in applied ecology (diatom-based assessments and monitoring, environmental sciences etc.).

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BACKGROUND:
In spite of its indusrial usefulness and varied daily uses, lead (Pb) pollution is a widespread ecological problem that faces the humans in the 21th century. Pb was found to produces a wide range of toxic effects including neurotoxicity especially to the developing and young offspring. Recently, the utilization of herbal plants has received a significant attention where there has been rising awareness in their therapeutic use; among these is the garlic.
AIM OF THE WORK:
In light of the above, the current study is designed experimentally in female pregnant rats in order to investigate the beneficial role of garlic extract in the protection from the maternal and fetal cerebellar damage that produced by administration of different doses of Pb during pregnancy.
MATERIALS AND METHODS:
Positively pregnant female rats were divided into five groups; one control group, two Pb-treated groups (exposed to 160 and 320 mg/kg b.wt. of Pb, respectively) and two groups treated with both Pb and garlic (exposed to Pb as previous groups together with 250 mg/ kg b.wt. /day of garlic extract). Treatments started from day 1 till day 20 of pregnancy, where the mother rats of different experimental groups were sacrified to obtain the fetuses. Pb level in the maternal nd fetal blood and cerebellum was estimated by spectrophotometry. Specimens of the cerebellum of different mother and fetal groups were processed to histological and immunohistochemical staining for microscopic examination.
RESULTS:
The results showed that administration of Pb to pregnant rats resulted in a dose-dependent toxicity for both mothers and fetuses in the form of decrease of maternal weight gain, placental and fetal weights, brain weight and diminished fetal growth parameters, which were prominent in rat's group treated with larger dose of Pb. In Pb-treated rats, Pb level in blood and cerebellum was high when compared to the control. The histopathological examination of the cerebellum of treated dams and fetuses showed marked alterations mainly in the form of Purkinje cell degeneration and lack of deveopmet of fetal cerebellum. Co-treatment of garlic extract along with Pb resulted in a significant decrease in Pb levels as compared with those treated with Pb alone with improvement of the histopathological changes.
CONCLUSIONS:
This study was useful in evaluating the hazardous effects of uncontrolled use of Pb in general and in assessing the developmental and neurotoxicity of fetuses due to exposure during pregnancy in particular. Co-administration of garlic has beneficial effects in amelioration of Pb-induced neurotoxicity and reversing the histopathological changes of the cerebellum of mother rats and fetuses.
KEYWORDS:
garlic; glial fibrillary acidic protein; lead; purkinje cells

A comparative study of physico-chemical parameters of two freshwater ponds was conducted to assess the seasonal variation in temperature, pH, dissolved oxygen, free carbon dioxide, alkalinity and hardness. The result showed that the value of the dissolved oxygen was recorded in the range of 3.6 mg/L to 7.9 mg/L, free carbon dioxide in the range of 33.8 mg/L to 50.0 mg/L, alkalinity in the range of 140 mg/L to 330 mg/L, hardness from 41 mg/L to 130 mg/L. During entire study period from July 2018 to June 2019, authors observed a great seasonal variation in the values of physico-chemical parameters.

The present investigation was an attempt to study the zooplankton community of Sathanur reservoir of Thiruvannamalai, Tamilnadu, India. The zooplankton species composition was studied for a period of one year from October 2018 to September 2019 on monthly interval basis. As a result of study, 24 zooplankton species were identified, out of which 9 were Rotifers, 7 Cladocerans, 5 Copepods and 3 Ostracodans. The overall population density of zooplankton was found maximum during the summer season and mininmum during monsoon. They play a supportive role in fish culture by recycling of nutrients and increase the soil fertility and involve in energy transfer between phytoplankton and fishes.

Diatom assemblages in carbonate spring habitats at low elevations, with low discharge, and affected by direct human impacts were studied only recently and in some geographic areas. We describe and characterize the ecology of a new Navicula species from springs with these characteristics within the basin of the River Adige in the south–eastern Alps and Alpine foothills (Province of Verona, Italy). Navicula veronensis sp. nov. is in the group of species around N. cincta but has distinct outline, size, central area, and proximal raphe endings. The availability of data on the distribution of the new species in streams of the Island of Cyprus allowed to quantitatively compare the ecological preferences, niche position, and niche breadth of Navicula veronensis sp. nov. with those of allied species. The new species was found to be characteristic of medium–high conductivity freshwaters, rich in sulphates and chloride, often nitrate enriched and affected by marked discharge fluctuations and seasonal desiccation. Niche position however differed only slightly from those of morphologically–similar species, with the exception of Navicula dealpina that was found to be characteristic of oligotrophic, calcium– bicarbonate rich environments with medium(–low) conductivity. Canonical Correspondence Analysis clearly showed that the most influential environmental variables determining the diatom assemblages of low–elevation carbonate springs affected by anthropogenic disturbance were nitrate enrichment, spring morphology alteration (in particular for water abstraction), and low discharge.

On the basis of LM and SEM observations as well as of environmental data, three species of the predominantly-acidophilous diatom genus Eunotia (E. cisalpina, E. fallacoides, E. insubrica) are described as new to science, and characterized from the ecological point of view. The three new species were not distinguished from other similar ones in the past but can be identified at the LM by careful observation of diacritical characters such as valve outline (in particular the shape of the endings), dimensions, and stria density. One of the three new species (E. insubrica) presents a very peculiar ultrastructural feature, i.e. well-developed pseudoseptum-like structures at the apices. The three new species were pointed out by detailed analyses of materials sampled in the south-eastern Alps. It is put forward that diatom investigations adopting high-resolution taxonomy are particularly opportune in habitats such as those colonized by the three new species. The three new species were found...

Lake Hawassa is one of the many freshwater shallow lakes found in the central Ethiopian Rift Valley. The sum totalities of aquatic and terrestrial habitats adjoining the lake facilitate for the rich diversity of flora and fauna compared to other Ethiopian Rift valley lakes. Scores of species with sundry forms of plants, animals and microorganisms make the lake extremely bio-diverse. The littoral area is covered with emergent and submerged macrophytes those serve as shelter, thrashing and proliferation zones for several benthonic and pelagic zoo-planktons such as Protozoans, Rotifers, Crustaceans, and several weed bed fauna like annelids, insects as well as fishes. The littoral and open water of the lake is dominated by wide-ranging delivery of 'qetema' (Cyperaceae), 'fila' (Typha sp.), the floating grass Paspalidium germina-tum and hydrophytes such as the Blue water lily (Nymphaea coerulea), water cabbage (Pistia stratiotes) and Wolfia arrhiza, considered to be the smallest flowering plant in the world.(Tilahun et al., 1996, EFASA-2013). The lake is among one of the biggest bird sanctuaries in the rift and homeland for several hundred species of water birds, including local and palaearctic migrants with large population of Marabou storks. The animal population includes large hippopotamus, otters, monitor lizards, Velvet and Colobus monkeys surviving on flanking lake ecosystem. Six varieties of fishes are abundantly found in the lake of which the native African species Tilapia (Oreochromis niloticus) are dominant. The lake is a major source of income through eco-tourism while the inhabitants depend on the lake for fishing and recreation. Present investigation is a maiden attempt to bring out first hand information by this visiting investigator who made a general enquiry for a small period of time to understand the ecosystem and species diversity of fresh water lakes of Ethiopia.

Adults resemble small, drab, grey moths, varying in size from minute (wingspans of <3mm) to large (wingspans approaching 100mm). Some species have striking colours and wing patterns. Wings held over the body in roof-like fashion when at rest, and covered with fine hairs, distinguishing caddisflies from their closest relatives, the Lepidoptera, whose wings are covered with scales. Trichoptera adults have prominent, and sometimes very long, antennae (up to twice the length of the forewing). Adults rest on vegetation near streams and are frequently found under bridges or overhanging trees and rock formations during the day, their active flying period being mainly at dawn or dusk. To find mates, some species form swarms, consisting mostly of males waiting to attract females, while others make use of chemical attraction. Adults feed on nectar and drink water and can live from two weeks to about two months. Larvae, which represent the longest-living phase of the life cycle (of up to two years), are all aquatic and show a great diversity of adaptations for life in freshwater ecosystems. They use their labial silk glands to construct portable cases or fixed shelters as well as meshed nets for capturing prey or lining burrows. They frequently add sand grains and stones or bits of bark, twigs, leaves and other plant matter to their cases and shelters to provide camouflage and ballast or buoyancy. These adaptations have made them one of the most successful freshwater groups globally. Diagnostic features of caddisfly larvae are the presence of a fully sclerotised (hardened) head, three pairs of segmented thoracic legs and a pair of terminal abdominal anal prolegs (additional 'false legs') with claws. With 14,548 species worldwide, they are the largest order of aquatic insects. In southern Africa 19 families, 54 genera and 230 species have been recorded, but it is estimated that well over 300 species occur in the region. Tibial spur formula of adults is used to distinguish families – the formula indicates the number of spurs on the tibia (second long segment of leg, leading to the tarsus or 'foot') of the fore-, mid-and hindlegs.

Aquatic Plants is a plant that can live in water such as seaweeds, ferns and many other types with special functions in natural habitats. However, now, these aquatic plants have been commercialized for use in decorating fish aquariums to further enhance the attractiveness of the aquarium. In the meantime, aquatic plants are commercialized and sold in the hobby industry to keep ornamental fish in the aquarium actually have some functions. For beginners, aquatic plants are to beautify the aquarium. But for hardcore enthusiasts who prioritize the natural process, planting aquatic plants is more to seek satisfaction. By planting aquatic plants in the aquarium, we can learned that aquatic plants are important to supply oxygen in the aquarium naturally and can absorb carbon dioxide gas released by fish, thus completing natural carbon cycle. Aquatic plants in aquariums can also be a source of natural food for some species of fish that eat leaves or grass and will be a place of fish protection from predators, shelters of laying fish and also as a place of play.

Aquatic macroinvertebrates are affected by physical, chemical and biological conditions of the stream. Some of them are pollution-sensitive while others are pollution-tolerant. They are good indicators of stream health. This study was conducted to determine the status of Labo and Clarin Rivers using macroinvertebrates as bioindicators. Dip-net and kick-net methods were employed. Results showed that sampling sites in forested areas in Labo and Clarin rivers had a higher macroinvertebrate taxa richness and abundance. Mayflies (Ephemeroptera) were the dominant macroinvertebrates. Ephemeroptera, Plecoptera, and Trichoptera (EPT) and %EPT indices were higher in Clarin than Labo River. Based on Family-level biotic index (FBI), the water quality of sampling site 1 in Clarin (forested site) was excellent (organic pollution is unlikely) and very good (possible slight organic pollution) for site 1 in the Labo River but decreased downstream (fair to good quality). MANOVA results revealed a significant difference in the macroinvertebrate abundance in the agricultural sites of Labo River and forest sites of Clarin River. Cluster analysis showed that among the macroinvertebrates, mayflies (Ephemeroptera) were distinct in the forest sites and bugs (Hemiptera) in agricultural sites on Clarin River. Fly larvae (Diptera) and beetles (Coleoptera) were distinct in agroforest sites of the Clarin River while abundant in agricultural sites on Labo River. Results indicate a need for monitoring and proper management of Labo and Clarin rivers to prevent increasing deterioration of water quality.

In freshwater bodies algae provide key ecosystem services such as food and water purification. This is the first systematic assessment of biodiversity, biomass and distribution patterns of these aquatic primary producers in the Okavango Delta
(Botswana), a subtropical flood-pulsed wetland in semiarid Southern Africa.
This study delivers the first estimate of algal species and genera richness at the Delta scale; 496 species and 173 genera were observed in 132 samples. A new variety of desmid (Chlorophyta) was discovered, Cosmarium pseudosulcatum var. okavangicum, and species richness estimators suggestthat a further few hundred unidentified species likely live in this wetland. Rare species represent 81% of species richness and 30% of total algal biovolume. Species composition is most
similar within habitat types, thus varying more significantly at the Delta scale.
In seasonally inundated floodplains, algal species / genera richness and diversity are significantly higher than in permanently flooded open water habitats. The annual
flood pulse has historically allowed more diverse algal communities to develop and persist in these shallower and warmer environments with higher mean nutrient levels and more substrata and more heterogenous habitats for benthic taxa. These results support the Intermediate Disturbance Hypothesis, Species-Energy Theory and Habitat Heterogeneity Diversity hypotheses. Higher algal biodiversity supports higher algal biomass in the floodplains, where species form three-dimensional communities of attached and periphytic algae requiring more nutrients than phytoplankton assemblages. Multivariate analyses demonstrate that habitat type,
flooding frequency and conductivity most importantly influence the relative abundance of algal species, genera and phyla in the Okavango Delta.
This study’s findings highlight how the preservation of water level fluctuations and habitat heterogeneity is crucial to maintaining biodiverse and thus resilient food webs in this unique ecosystem which faces increasing anthropogenic threats, such as global warming and upstream water abstraction plans.

In European countries, hydromorphological (HyMo) pressures are the second most commonly occurring types of pressures on aquatic ecosystems (after eutrophication). HyMo pressures, i.e. man-made alterations to the hydrology and morphometry of aquatic ecosystems, impact the functioning of lakes and rivers in multiple ways. Initially, they have profound effects on littoral communities-such as macrophytes, benthic invertebrates, and fish. Ultimately, they result in pervasive alteration of whole-lake ecosystems. Huge efforts have been devoted to the development of ecological assessment methods and management measures focusing mainly on eutrophication, whilst HyMo alterations are less understood and not properly addressed. We attempt to clarify the conceptual background, to highlight achievements in method development, including pressure-response relationships and metrics used in assessment, and to underscore issues requiring urgent attention. We conclude that the currently used biological methods do not reliably address HyMo alterations. It is urgent to develop specifically-responding biological and HyMo assessment methods, and to measure the necessary variables in routine monitoring programs. This review paper also serves as an introductory article to a small special series of papers on the ecological impacts of water level fluctuations. Papers in this series also include an updated literature review on the ecological effects of water level fluctuations on lake macroinvertebrates, a review article specifically devoted to water level fluctuations indicators in the littoral of natural and artificial lakes, and a paper addressing the relationships between WLF alteration and spatial and temporal patterns of cladoceran communities in a dammed lake.

With 67 figures and 6 tables Cantonati, M., H. Lange-Bertalot, F. Decet & J. Gabrieli (2011): Diatoms in very-shallow pools of the site of community importance Danta di Cadore Mires (southeastern Alps), and the potential contribution of these habitats to diatom biodiversity conservation. – Nova Hedwigia 93: 475–507. Abstract: Mires are very selective habitats, and the colonisation by specifically adapted organisms makes them very important both for nature conservation and environmental education. They have, however, been threatened by different types of impacts. Our objective was to study diatoms in stations representative of the main typologies in the Site of Community Importance IT3230060 "Danta Mires", also to produce data for a management plan in the frame of a Life Project. Five shallow pools within different mountain mires were sampled in summer 2005 and morphologically and physicochemically characterized. The sampled sites cover a rather wide pH and TDS content gradient with very low nitrate and silica values. Diatoms were found to dominate in terms of numbers of taxa, followed by desmids, cyanoprokaryotes and filamentous green algae. In total, 86 diatom taxa, belonging to 35 genera, were found. As expected for acidic, low-mineralization waters the genera with the highest number of taxa were Eunotia and Pinnularia, followed by Encyonema, Cymbopleura, Gomphonema, and Nitzschia. The most frequent and abundant taxa were: Frustulia crassinervia, Nitzschia acidoclinata, Kobayasiella micropunctata, Encyonema neogracile, Brachysira brebissonii, Nitzschia perminuta, and Encyonema lunatum. Taxa abundant only in one or few sites were: Eunotia paludosa, Staurosira spinarum, Encyonopsis cesatii, and Achnanthidium minutissimum. Several rare taxa of special interest for their distribution and/or rarity could be found (e.g. Chamaepinnularia schauppiana, Cymbopleura incertiformis var. linearis, C. subapiculata, Eunotia lapponica, Microfissurata paludosa). On average,

Climate change and extreme weather events are an ever-increasing concern on planet earth during this epoch called the Anthropocene. Water is front and centre in all these experiences from oceans rising, to increased floods and insect-borne diseases thriving in murky water. What can we do? We can all get involved in understanding how water moves around the planet, and our responsibility to sustain clean and accessible flows. Welcome to the launch of the AquaMOOC! This MOOC is a free online learning tool for everyday citizen scientists, secondary school students, and entry level university students. Out specific focus is water, hence, the name AquaMOOC. One of the aims

Addenda, including both bibliographic references and images, to my 2004 book Floating Islands: A Global Bibliography, With an Edition and Translation of G. C. Munz’s Exercitatio academica de insulis natantibus (1711). The work includes geographical and thematic indices, and an illustrated "Narrative of a Visit to the Floating Island in Derwentwater, England."

The present paper contains an analysis of the available information dealing with the diversity of algae from Danube Delta Biosphere Reserve. Undesirable mistake: wrong nominalization of the scientific names which have been found in reference sources or synonyms of the species have been crowed out from the revised checklist.

The former Synedra rumpens complex has long puzzled diatom taxonomists. In the nineteenth century, many infraspecific taxa were described as varieties or forms of S. rumpens. In the present study, type material of Synedra rumpens and several infraspecific taxa such as S. rumpens var. fragilarioides and S. familiaris f. parva and f. major was investigated using LM and SEM observations. For comparison, the original material of several other relevant diatom taxa (such as Fragilaria perdelicatissima, F. spinaspeciosa, Synedra campyla, S. vaucheriae var. distans) was also analysed. The results based on these comparisons show that all infraspecific taxa should be split from Fragilaria rumpens. Fragilaria campyla is a new combination within the genus Fragilaria with F. parva and S. (rumpens var.?) familiaris f. major as synonyms. Fragilaria scotica is likewise a new combination in Fragilaria. Fragilaria metcalfeana is proposed as new name for Synedra familiaris var. neogena. The analysis of F. distans and F. fragilarioides confirmed their conspecificity, with F. fragilarioides having priority as name. Finally, two new species, F. pseudofamiliaris Van de Vijver, T.M.Schuster, Kusber et D.M.Williams sp. nov. and F. bahlsiana Van de Vijver, C.E.Wetzel et Ector sp. nov. are described. Using an analysis of the associated diatom flora, the ecological preferences of each taxon are briefly discussed.

This paper reviews the current knowledge of the heterotrophic and anoxygenic photosynthetic bacteria in Lake Kinneret. Morphological and phylogenetic diversity of bacteria and archaea as well as data from routine total bacterial cell counts are summarized. From 2001 to 2011, there was a definite, significant trend to lower the annual average cell counts that coincided with a significant decrease in bacterial productivity. Additional information is provided on anoxygenic phototrophic bacteria prevailing in Lake Kinneret. The most abundant of these phototrophs is the green sulfur bacterium (GSB) Chlorobium phaeobacteroides Pfennig. It forms (almost consistently) a prominent layer in the metalimnion from June through October. The spatial distribution of BChl e, an indicator of C. phaeobacteroides, was fairly heterogeneous, and its peak values often exceeded the record of chlorophyll a peaks. C. phaeobacteroides was identified as a major contributor to the sedimenting material in the lake in the summer, making up on average 27 % of the carbon settling towards the bottom.

The Lake Victoria Basin is home to the most extensive wetlands in Eastern Africa and these wetlands support remarkably high levels of floral biodiversity. Freshwater plants have a diverse range of uses, with variations in use depending on the plant part and life stage. Medicinal use of plants is very common in rural communities, as there is often no access to modern medical facilities, and investigations of the medicinal properties of plants have been conducted for centuries.

Given these attributes, Lake Victoria (and its basin) is uniquely central to curbing problems of both malnutrition and poverty if measures can be put in place to ensure sustainable use of its biodiversity. In this chapter, we provide a summary of our detailed assessment of the use and livelihoods value of the freshwater fishes and plants of the Lake Victoria Basin. The aim of this assessment was to collate information on the many and varied uses of these species, in order to increase awareness of their great importance to the livelihoods of the communities of the Lake Victoria Basin, and demonstrate that conservation of this biodiversity is of vital importance.

Freshwater mollusks have received little attention from conservation scientists. We collected museum records and conducted an inventory of freshwater mollusks to develop a species checklist for the Buriganga and Turag Rivers. The study area extended from the Posthoghola Bridge (

Herbivory is a fundamental process that controls primary producer abundance and regulates energy and nutrient flows to higher trophic levels. Despite the recent proliferation of small-scale studies on herbivore effects on aquatic plants, there remains limited understanding of the factors that control consumer regulation of vascular plants in aquatic ecosystems. Our current knowledge of the regulation of primary producers has hindered efforts to understand the structure and functioning of aquatic ecosystems, and to manage such ecosystems effectively. We conducted a global meta-analysis of the outcomes of plant–herbivore interactions using a data set comprised of 326 values from 163 studies, in order to test two mechanistic hypotheses: first, that greater negative changes in plant abundance would be associated with higher herbivore biomass densities; second, that the magnitude of changes in plant abundance would vary with herbivore taxonomic identity. We found evidence that plant abundance declined with increased herbivore density, with plants eliminated at high densities. Significant between-taxa differences in impact were detected, with insects associated with smaller reductions in plant abundance than all other taxa. Similarly, birds caused smaller reductions in plant abundance than echinoderms, fish, or molluscs. Furthermore, larger reductions in plant abundance were detected for fish relative to crustaceans. We found a positive relationship between herbivore species richness and change in plant abundance, with the strongest reductions in plant abundance reported for low herbivore species richness, suggesting that greater herbivore diversity may protect against large reductions in plant abundance. Finally, we found that herbivore–plant nativeness was a key factor affecting the magnitude of herbivore impacts on plant abundance across a wide range of species assemblages. Assemblages comprised of invasive herbivores and native plant assemblages were associated with greater reductions in plant abundance compared with invasive herbivores and invasive plants, native herbivores and invasive plants, native herbivores and mixed-nativeness plants, and native herbivores and native plants. By contrast, assemblages comprised of native herbivores and invasive plants were associated with lower reductions in plant abundance compared with both mixed-nativeness herbivores and native plants, and native herbivores and native plants. However, the effects of herbivore–plant nativeness on changes in plant abundance were reduced at high herbivore densities. Our mean reductions in aquatic plant abundance are greater than those reported in the literature for terrestrial plants, but lower than aquatic algae. Our findings highlight the need for a substantial shift in how biologists incorporate plant–herbivore interactions into theories of aquatic ecosystem structure and functioning. Currently, the failure to incorporate top-down effects continues to hinder our capacity to understand and manage the ecological dynamics of habitats that contain aquatic plants.