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В работе кратко рассмотрена эволюция подхода к оценке воздействия ионизирующей радиации на живые организмы. На примере черноморских гидробионтов показана возможность применения концептуальной радиохемоэкологической модели зональности действия хронического облучения ионизирующих излучений в природе Г. Г. Поликарпова для оценки уровня экологического воздействия ионизирующего излучения от техногенных радиоизотопов на водную биоту. Эта модель может служить в прикладной гидробиологии основой комплексного подхода к оценке экологического состояния водной биоты и его прогноза для широкого диапазона концентраций активности 239,240Pu в морской воде. Подчёркивается необходимость совместного применения биогеохимического и эквидозиметрического показателей поведения радиоизотопов в водоёме. В частности, для прогнозных дозиметрических оценок важно учитывать количественные характеристики концентрирующей способности черноморских гидробионтов и тип биогеохимического поведения радиоэлемента, отражающие особенности биогеохимической миграции плутония в морской экосистеме.

The paper deals with the main historical moments of the Caspian sturgeon population dynamics and the formation of their stocks. The participation of researchers of the Department of Ichthyology and Hydrobiology of Saint-Petersburg State University in creating the concept of sturgeon conservation in the Caspian Sea and the specialized institute of sturgeon farming in Astrakhan was highly appreciated. The materials on the contribution of the Department’s researchers to the study of the physiological state of sturgeon producers, improving their quality, survival and safety in the conditions of artificial breeding of these species are presented. The data on the reduction of the sturgeon abundance reared and released into the Caspian Sea by the Caspian littoral states are presented. A description of the current state of the sturgeon of the Caspian basin is given. The data on changes in stocks, the structure of the spawning part of the population and reproduction of the beluga, Russian sturgeon and stellate sturgeon in the Volga-Caspian basin under the conditions of the prohibition of their commercial fishing are analyzed. It was shown that during the years of the ban, the abundance and stocks of sturgeon and biological indicators of breeding migrants to spawn in the Volga continued to decrease and the proportion of females among them, which is associated with the illegal catch of sturgeon, comparable in scale to the commercial fishery before the ban was introduced. Reduced natural (up to its complete cessation in the Beluga) and artificial reproduction of sturgeons are stated. Only observing the moratorium on sturgeon fishing in all the Caspian littoral states, strengthening the protection of fish at feeding grounds and spawning migrations can preserve and restore their unique Caspian populations.

The present article is dedicated to the 90th anniversary of the foundation of the Department of Ichthyology and Hydrobiology in Saint-Petersburg State University, as well as to the formation of ichthyological school by talented scientist and bestow teacher Professor Nikolai Lvovich Gerbilcky. The results of fundamental works which were fulfilled during much time when using the principle of ecological histophysiological analysis laid by N.L. Gerbilsky are shown in this article. Also the results of the analysis of species adaptations connecting with the reproduction of fishes and with survival of its progeny when using this new method were presented. The basic principles of the biotechnology of fish reproduction in industrial conditions were created because of these results. The sphere of the principles of morphological-physiological analysis were expended and continued by following leaders of the Department and Laboratories – the schoolers and the followers of N.L. Gerbilsky. The mechanisms of hormonal regulation of fish’s gametogenesis were studied and the patterns of phase changes in the regulation and ecological – physiological staging of fish’s gametogenesis were opened by B.N. Kazansky. Fundamental investigations of osmotic and ionic regulation in different species of acipenserids and salmonids from the perspective of ecological morphological physiology when using present experimental methods leaded up to the creation of new direction in the study of fish osmoregulation and its adaptation to water with different salinity by L.S. Krayushkina and her pupils and colleagues. The mechanisms of regulation of the gametogenesis and the functions of sex gonads, the differentiation of fish sex and the influence of extremal factors on the process of gameto- and gonad genesis in different fishes were investigated by G.M. Persov and his Laboratory of Experimental Ichthyology. The use and the development of the principle of Gerbilsky’s method outside the Department by his pupils were presented: in the creation of the theory of functional basis of fish migrations, in the studies of endocrine regulation of reproductive cycle in acipenserids and salmonids by I.A. Barannikova and colleagues of her Laboratory. Structural and functional peculiarities of hypothalamic-hypophysial neurosecreting system of fishes were studied by A.L. Polenov. The continuation of traditional ruse to the analysis of different fish adaptations were demonstrated in the investigations of the ichthyologists at present time.

In some cases, wildlife management objectives directed at multiple species can conflict with one another, creating species trade-offs. For managers to effectively identify trade-offs and avoid their undesirable outcomes, they must understand the agents involved and their corresponding interactions. A literature review of interspecific trade-offs within freshwater and marine ecosystems was conducted to illustrate the scope of potential interspecific trade-offs that may occur. We identified common pitfalls that lead to failed recognition of interspecific trade-offs, including, single-species management and limited consideration of the spatial and temporal scale of ecosystems and their management regimes. We devised a classification framework of common interspecific trade-offs within aquatic systems. The classification can help managers determine whether the conflict is species based through direct relationships (i.e., predator-prey, competition, other antagonistic relationships) or indirect relationships involving intermediate species (i.e., conflict-generating species) or whether the conflict is driven by opposing management objectives for species that would otherwise not interact (i.e., nontarget management effects). Once the nature and scope of trade-offs are understood, existing decision-making tools, such as structured decision-making and real-options analysis, can be incorporated to improve the management of aquatic ecosystems. Article Impact Statement: A synthesis of interspecific trade-offs in aquatic ecosystems supports their identification and resolution.Un Marco de Clasificación para Compensaciones Interespecíficas en Ecología Acuática Resumen En algunos casos, los objetivos del manejo de fauna dirigidos a muchas especies pueden entrar en conflicto entre sí creando compensaciones entre las especies. Para que los manejadores identifiquen efectivamente estas compensaciones y eviten sus resultados no deseados, deben entender a los agentes involucrados y sus interacciones correspondientes. Se realizó una revisión literaria de las compensaciones interespecíficas dentro de los ecosistemas marinos y de agua dulce para ilustrar el alcance de las compensaciones interespecíficas que pueden ocurrir. Identificamos dificultades comunes que llevan al reconocimiento fallido de las compensaciones interespecíficas, incluyendo el manejo de una sola especie y sus regímenes de manejo. Diseñamos un marco de clasificación de compensaciones interespecíficas comunes dentro de los ecosistemas acuáticos. La clasificación puede ayudar a los manejadores a determinar si el conflicto está basado en las especies por sus relaciones directas (es decir, depredador-presa, competencia, otras relaciones antagonistas) o por relaciones indirectas que involucran a otras especies (es decir, efectos del manejo de especies que no son el objetivo). Una vez que se entiende la naturaleza y el alcance de las compensaciones, las herramientas de toma de decisión existentes, como la toma estructurada de decisiones y el análisis de opciones reales, pueden incorporarse para mejorar el manejo de los ecosistemas acuáticos.

Information on the first findings of Gaillona rosea (Roth) Athanasiadis 2016:814 (Aglaothamnion roseum (Roth) Maggs & L’Hardy-Halos 1933:522) in the Russian part of the South-Eastern Baltic is given. Samples of algae in the Russian part of the South-Eastern Baltic along the coast of the Kaliningrad region at depths of 1–15 m were collected by diving method on the north coast of the Sambian Peninsula near Cape Taran and Cape Gvardeysky at the stations confined to hard ground. First samples of G. rosea collected from drifting mats of perennial algae Furcellaria lumbricalis and Polysiphonia fucoides were first registered along the west and north coast of the Sambian Peninsula (Cape Taran) at depths of 1.5–7 m in autumn 2015. The finding of the species in 2015 on the west coast of the Sambian Peninsula is the first registration for the coast of the Gdansk Bay. In July 2016, the species was found in samples at Cape Taran at a depth of 0.5 m. The length of the thalli does not exceed 3 cm. The species was registered with F. lumbricalis and P. fucoides, both in attached communities and in drifting mats. G. rosea is quite common in the Baltic Sea, with the exception of the Gdansk Bay and the northernmost part of the Baltic Sea, where the salinity is low. There is no data available on the abundance of the species in the adjacent Lithuanian waters. The species is rarely registered in the Russian part of the South-Eastern Baltic, and therefore G. rosea is rare in the entire South-Eastern Baltic Sea.

The rate of linear and weight growth of triploid spat of oyster Crassostrea gigas in Donuzlav Liman (Black Sea, Crimea) was investigated. A quantitative relationship between the mass (W, g) of the whole oyster and the height of the shell (H, mm) is given (it is described by the equation W = 7 · 10-5 · Н3.1, R² = 0.78), as well as a quantitative relationship between the mass (W, g) of the whole oyster and the length of the shell (L, mm) (W = 3 · 10-4 · L3.12, R² = 0.65). The maximum rates of linear growth of triploid oysters T20 were registered in April (1.15 mm per day), of weight growth – in June (0.50 g per day) and August (0.61 g per day). It was shown that 27 % of triploid oysters T20 can reach commercial size after 6 months. It is recommended to use Pacific oysters of T20 size as a planting material on the shellfish farms in the Black Sea region.

Несмотря на запрет применения хлорорганических соединений (ХОС), они до настоящего времени аккумулируются в различных абиотических и биотических компонентах экосистемы Чёрного моря, в том числе в рыбах, вызывая негативные изменения в их метаболизме. Как район активного хозяйственного использования, севастопольская морская акватория подвергается значительному антропогенному воздействию. Уровень содержания ХОС в тканях морского ерша (скорпены) Scorpaena porcus Linnaeus, 1758, ведущего оседлый образ жизни и массово распространённого в прибрежных сообществах, может служить показателем степени загрязнения акватории данным поллютантом, а вид ― удобным индикатором. Газохроматографическим методом с использованием микродетектора электронного захвата определены качественный состав и концентрация хлорорганических пестицидов (п,п’-ДДТ и его метаболитов) и шести индикаторных конгенеров полихлорированных бифенилов в 58 пробах белых мышц, гонад и печени морского ерша, отловленного в 2016–2017 гг. в различных по степени загрязнённости бухтах региона Севастополя (Александровская, Казачья, Стрелецкая, Балаклавская, Ласпи), а также в открытой прибрежной акватории. Для определения отклика организма на уровень загрязнения в печени ерша исследовали комплекс биохимических маркеров: активность аланинаминотрансферазы, аспартатаминотрансферазы и каталазы, содержание альбумина, уровень окислительной модификации белков и концентрацию малонового диальдегида. Содержание ХОС в рыбах зависело от загрязнённости места их обитания. Наибольший уровень ХОС зафиксирован в органах ершей из бухт закрытого типа с затруднённым водообменом (Александровская, Стрелецкая и Балаклавская), наименьший ― в открытой бухте Ласпи. Накопление ХОС в органах ершей зависело от содержания липидов в исследованных тканях. Максимальные концентрации ХОС обнаружены в печени скорпен из всех изученных акваторий, минимальные ― в гонадах рыб из бухт и в белых мышцах особей из открытых районов. Полученные соотношения между содержанием ХОС в печени ерша и показателями комплекса биохимических маркеров свидетельствуют об ослаблении антиоксидантной защиты и о развитии окислительного стресса у рыб в результате накопления ксенобиотиков.

The role of mussels in formation of water chemical composition is determined by the peculiarities of sorption and trophodynamic processes. Copper is a vital element, but of ten metals the toxic effect of which was tested for the survival of mussel and oyster embryos, copper is following mercury. Studying the regularities of copper content change during mussel ontogeny allows to determine both sanitary and hygienic risks of mussel product use during the mollusks cultivation in mariculture and the biogeochemical role in the formation of the chemical composition of the marine water near mussel farms. The purpose of this work is to determine the copper content in the organs and tissues of the mussels during seasonal course of mollusks ontogenesis, to analyze the degree of copper assimilation along the food path of mineral nutrition using the mathematical model and empirical data and to assess the influence of marine farms on the copper exchange processes in the coastal ecosystem. The mollusks were collected from the mussel farm located in the external roadstead of Sevastopol. Studying the copper content in the environment – mussel – biodeposition system, a method of atomic absorption spectroscopy with electrothermal atomization was used. A general model illustrating the process of copper exchange between the mussels and the water environment is presented. Equations for determining the degree of assimilation of metal from food (q) and the limiting coefficient of food accumulation of metal (Кп) are proposed based on the results of measurements of its concentrations in the mussels’ diet, soft tissue and their biodeposition without using radioactive trace elements. The values of the copper removal by the mussel farm were calculated. The role of cultivated mollusks in the heavy metals precipitation was shown.

Data on hydrology, hydrochemistry, and hydrobiology, including the fish population, of Lake Urozero (southern Karelia) are given. The results of the work on the introduction of two fish species carried out in Lake Urozero for improving the quality of the ichthyofauna have been analyzed. In the1950s–1990s, the whitefish Coregonus lavaretus and the European vendace C. albula were repeatedly introduced into the lake. Of the two species, only vendace has become naturalized in the lake. Its biological features in the new habitat conditions have been studied. A comparative analysis of linear–weight parameters with characteristics of the vendace from the donor reservoirs has been carried out. The results make it possible to classify the vendace of Lake Urozero as a large-sized form. Whitefish has not naturalized, which may be due to the small volume of its introduced stocking material and weak viability of the introducing material. Currently, eight species of fish live in the lake. Perch Perca fluviatilis and vendace prevail in abundance. Biological parameters of perch are presented. Currently, vendace constitutes a significant portion in the diet of large-sized perch.

Morphophysiological studies of hydrobionts, and, in particular, mussels cultivated in marine farms, become important for modern hydrobiology. The study of the phenotypic structure of the mussel settlements in the Black Sea is an important aspect of monitoring the state of the mollusk population in changing environmental conditions. Information about patterns of sex realization under certain conditions can be the basis for active management of settlement formation in the cultivation of mollusks. Data about the regularities of sexual maturation of mussels, the stages of maturity of gonads and gametes spawning are also of importance. The aim of the work was to assess the phenotype and sex structure of the mussel populations as well as the stages of gonads maturity of the mussel Mytilus galloprovincialis cultivated on the mussel-oyster farm located in the outer harbor of Sevastopol. Mussels with the size of the shell from 4.9 to 5.4 mm were collected monthly from March 2015 to August 2016 on the studied mussel-oyster farm. Phenotype, sex and stages of gonad maturity were determined in mollusks by standard methods. When determining the frequency of occurrence of mussel phenotype on the mussel-oyster farm, a higher percentage of mollusks with black color shells (Bl) in comparison with whose with brown color shells (Br) was observed, and on average for the studied period the shell phenotype ratio (Bl : Br) was 1.8 : 1 respectively. Data on the sexual structure of M. galloprovincialis on the studied mussel-oyster farm are presented. Average ♂ : ♀ ratio was 2.8 : 1, with the proportion of hermaphrodites reaching 1–6 %. The sex ratio was different every month. In March 2015 it was 1.7 : 1 (♂ : ♀) and by August 2015, while mollusks growing on the mussel’s collector, the share of males reached its maximum (8 : 1). After thinning the mussels on the collector, the sex ratio had stabilized by October 2015 and remained at the level of 2 : 1 until March 2016. The next subsidence of the young and increase of mussels mass on the collector had again led to a significant shift of the mussel sexual structure (7.5 : 1) by May 2016. One of the reasons of the increase in the number of males in the studied mussel-oyster farm is thought to be the high density of mussels in the druse resulting in local hypoxia and poor food accessibility. The analysis of the state of gonads maturity of cultivated mussels showed two peaks of spawning – spring (March, April) and a long autumn one (started in October and continued until early December). Mass reproduction of mussels was observed in the spring when the surface water layer warmed up to 9–12 °C and in the autumn with the decrease of water temperature to 18 °C. The asynchronous maturation of the gonads of M. galloprovincialis of both sexes was observed. Males had greater variability of maturity stages than females. The shift in the ratio of the sexes towards the increase of males share as well as the increase of the number of mussels with black color shell and also the asynchronous maturation of the gonads of M. galloprovincialis on the studied farm can be considered as the ecological and physiological response of mollusks to the environment changes.

Исследования криптобентической фауны имеют высокую актуальность при изучении биоразно образия регионов. С целью уточнения ихтиофаунистических списков различных районов черноморской прибрежной зоны Крыма проведены исследования видового состава семейства морских уточек Gobiesocidae и обнаружен новый для прибрежной зоны Крыма вид — малоголовая присоска, или аплетодон. Вследствие малой изученности и дискуссионного таксономического статуса этого вида сведения о его морфологии, биологии, поведении и других особенностях представляют немалую научную ценность. Доказано обитание малоголовой присоски у черноморских берегов Крыма, описаны популяционно-биологические (размерно-массовые, морфометрические) характеристики и особенности распространения. В результате морфологических исследований крымских экземпляров показано отсутствие существенных различий между ними и представителями вида из атлантическо средиземноморских популяций. Выявлены особенности местообитаний, которые предпочитает этот вид, и особенности локализации, представляющие преимущества при внутрисемейственной конкуренции. Приведены ключевые признаки, облегчающие видовое определение.

There is growing demand for biotechniques in oceanobiological and hydrobiological studies. Immunohistochemistry (IHC) combines anatomical, immunological and biochemical techniques to identify specific antigen-antibody interactions. Detecting the target antigen with labeled antibodies is a multi-step process that requires optimization at every level to maximize the signal detection. Here we use zebrafish samples and optimize each IHC step, particularly antigen retrieval, transgenic reporter double staining and background counterstaining. The resulting images with high signal intensity lead us to recommend the resulting protocols for experiments with fish.

Based on analysis of the original sources the specific roles of Russian Navy in the formation of national hydrobiology are investigated. Providing research and creating the material base for them, the fleet actually created the hydrobiological school, aimed at addressing their needs. And the most important thing is that it helped to provide independent and free from foreign ownership study of the southern region of the world.

The relationship between physicochemical factors and plankton abundance in the newly created Bui reservoir was studied during 2011 and 2012. The objective was to assess the influence of physicochemical factors on plankton abundance and provide data for monitoring the hydrobiology of the newly created Bui reservoir. Two sampling stations were selected on the Black Volta upstream (Bui) and downstream (Bamboi) of the dam, with samples taken pre- and postimpoundment during the study period. Canonical Correspondence Analysis (CCA) was used to trace temporal plankton community changes and to examine the relationships between species composition and physicochemical variables. The relative abundance of some phytoplankton species such as Anabaena sp., Planktothrix sp. and Scenedesmus sp. was directly correlated to nitrates. CCA indicated that physicochemical variables explained 41–64% of zooplankton and 8–12% of phytoplankton variation. Hence, there were correlations between environmental variables and the structure of plankton assemblages. This feature should therefore be used for bio-monitoring of environmental variables of the river by the Bui Power Authority to ensure protection of the aquatic biota downstream of the Bui dam. Resume Nous avons etudie en 2011 et 2012 la relation entre certains facteurs physico-chimiques et l'abondance du plancton dans le nouveau reservoir de Bui. Notre objectif etait d'evaluer l'influence de facteurs physico-chimiques sur l'abondance du plancton et de recolter des donnees pour le suivi de l'hydrobiologie dans ce nouveau reservoir. Nous avons selectionne deux stations d'echantillonnage sur le cours de la Volta noire, en amont (Bui) et en aval (Bamboi) du barrage, et preleve des echantillons avant et apres sa mise en eau. Une Analyse canonique des correspondances (ACC) fut utilisee pour suivre les changements de la communaute de plancton dans le temps et pour examiner la relation entre certaines especes de phytoplancton et des variables physico-chimiques. L'abondance relative de certaines especes de phytoplancton, tels Anabaena sp., Planktothrix sp. et Scenedesmus sp., fut directement liee aux nitrates. L'ACC indiquait que des variables physico-chimiques expliquaient de 41 a 64% des variations du zooplancton et de 8 a 12% de celles du phytoplancton. Il y avait donc des correlations entre des variables environnementales et la structure des assemblages de plancton. Cette caracteristique devrait donc etre prise en compte pour le bio-monitoring des variables environnementales de la riviere par les autorites hydro-electriques de Bui pour garantir la protection des biotes aquatiques en aval du barrage de Bui.

Some diatoms are rich food for herbivorous copepods, while others are toxic for their recruitment. No negative effect of diatom Cylindrotheca closterium was ever observed for copepods, and some estuarine copepods preferred it as a food. Data on grazing diatoms by abundant now in the Black Sea coastal waters invasive copepod Oithona davisae are still contradictory. Interaction of O. davisae and C. closterium, both having high colonizing potential and both typical for coastal waters, was studied in experimental culture. Two weeks after inoculation of C. closterium the cultured O. davisae was drastically fouled by globulous conglomerates of diatom cells. Diatom cells in “colonies” on copepod exoskeleton were interconnected by means of adhesive substances at one of their flexible ends at the point-wise areas at various parts of copepods exoskeleton, and the opposite flexible ends performed various circular roll-over fan-shaped movements around the axis passing through the point of their attachment. “Colonies” behaved as integrated aggressive organisms against any approaching flagellate and prevented normal locomotion of copepods. Herein we present the first report on epizoic behavior of C. closterium: quick disastrous colonization of alive copepods O. davisae by diatom “colonies” led to total extinction of cyclopoid experimental population while alive diatoms formed dense network on copepods degenerative tissues.

For turtles, the thermal environment experienced during development plays critical roles in many biological processes. While the temperature inside an egg is assumed to match the substrate temperature, many factors such as evaporative cooling, metabolic heating and the insulating properties of extra-embryonic components can lead to thermal differences. However, no method developed to date has allowed for measurement of the embryonic temperature in live chelonian eggs. We designed a thermocouple-based technique to measure embryonic temperature, achieving 94% survival in Trachemys scripta. This methodology may be applicable to other reptile species. We found that, while the temperature in the substrate adjacent to the eggshell accurately reflects the internal egg temperature, it differs from air temperature (∼2°C) in a moisture-dependent manner. Our results demonstrate that external egg temperature, but not air temperature, is suitable for assessing the effects of temperature on biological processes, which could be critical when considering that processes such as temperature-dependent sex determination in turtles occurs within a 4°C window.

Aquatic environments harbor a great diversity of microorganisms, which interact with the same patchy, particulate, or diffuse resources by means of a broad array of physiological and behavioral adaptations, resulting in substantially different life histories and ecological success. To date, efforts to uncover and understand this diversity have not been matched by equivalent efforts to identify unifying frameworks that can provide a degree of generality and thus serve as a stepping stone to scale up microscale dynamics to predict their ecosystem-level consequences. In particular, evaluating the ecological consequences of different resource landscapes and of different microbial adaptations has remained a major challenge in aquatic microbial ecology. Here, inspired by Ramon Margalef’s mandala for phytoplankton, we propose a foraging mandala for microorganisms in aquatic environments, which accounts for both the local environment and individual adaptations. This biophysical framework distills resource acquisition into two fundamental parameters: the search time for a new resource and the growth return obtained from encounter with a resource. We illustrate the foraging mandala by considering a broad range of microbial adaptations and environmental characteristics. The broad applicability of the foraging mandala suggests that it could be a useful framework to compare disparate microbial strategies in aquatic environments and to reduce the vast complexity of microbe-environment interactions into a minimal number of fundamental parameters., The ISME Journal, 13, ISSN:1751-7362, ISSN:1751-7370

We present a method for automating the measurement of upper thermal limits in small aquatic organisms. Upper thermal limits are frequently defined by the cessation of movement at high temperature, with measurement being performed by manual observation. Consequently, estimates of upper thermal limits may be subject to error and bias, both within and among observers. Our method utilises video-based tracking software to record the movement of individuals when exposed to high, lethal temperatures. We develop an algorithm in the R computing language that can objectively identify the loss of locomotory function from tracking data. Using independent experimental data, we validate our approach by demonstrating the expected response in upper thermal limits to acclimation temperature. © 2018. Published by The Company of Biologists Ltd http://creativecommons.org/licenses/by/3.0 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution and reproduction in any medium provided that the original work is properly attributed.

The waterlogging of commonly non-flooded soils acts as a filtering for plant communities. River impoundments can flood a large area never flooded before, changing the local conditions and affecting seeds and growing plants. Therefore, the recruitment process in the regenerating community on these new formed margins may be inhibited. Lists containing plant species indicated for restoration of periodically flooded habitats have been published but the germination and initial development behavior of these species are poorly known. We hypothesize that species indicated to restore flooded habitats (FH) are faster to germinate and their seedling also develop better than species from non-flooded habitats (NH) under waterlogging conditions. Seeds of species from flooded and non-flooded habitats were submitted to treatments of flooding (F) and non-flooding (N) for 90 days, and germination was daily registered. Seedlings of Psidium guajava and Handroanthus serratifolius were submitted to flooding and morphophysiological parameters were measured. Species from both groups had similar patterns of germination, and for most species flooding led to a faster germination. In general, the number of germinated seeds was smaller under flooding. P. guajava seedlings presented decreasing growth and photosynthesis under flooding and H. serratifolius seedlings presented chlorosis, foliar abscission, negative net photosynthetic rate, and root-rotting. Flooding was harmful for plants of both groups, but was worse for seeds and seedlings from NH species. The outcomes show that the use of plant species in restoration programs of dams and reservoir margins must take into account if it will be used seeds or seedlings, since the success and sustainability of this action will depend on the fast and well development of the plants.

Aim. Industrialization of Caspian oil and gas supplies requires a serious approach to the problem of protecting and preserving the region’s unique environment that, in fact, represents a property of international commons. The article studies into the impact of the Caspian modified waters on the benthos faunistic composition. Methods. Zooplancton and zoobenthos hydrobiology material was collected in the Central Caspian survey loop. Samples were collected in spring and summer in 2002 – 2007 in the western part of the Caspian Sea (Dagestan offshore location of the Caspian Sea from Smirnovsky Midstream Sandbank and Pearl Bank till Derbent latitude) on “Tsada” vessel. They were collected from 25 stations located on ten standard parallel latitude logs with depth scope of 8–100 m from 0, 10, 25, 100 m horizons. These samples were used as a material for characterizing phyto- and zooplankton. Results. The benthic can be considered the most stable communities of the marine environment as they are the most resilient to quantity and modifications. Heterogeneous and variable ecosystem (biotope) is typical of the areas with strong currents as the organic quality, quantity and physic-chemical properties are marked by variability. Location. The Caspian zoobenthos state as well as the features of the Caspian Sea benthos communities characterize the ecology of the Caspian Sea and give a true view of the situation in the drilling sites. This will help predict and avert negative effect of hydrocarbon production on the Caspian Sea ecosystem. Main conclusions. Water modification must be intensive, long-lasting and frequent for it to have an impact on benthos.

The keratinophilic fungi in various types of water bodies (slough. pond. beach pool. two lakes and two rivers) were studied. Samples of water were collected every other month for bydrochemical analysis and once a month (1989-1990) in order to determine the fungus content. Human hair, snippings of finger-nails, chips of hoofs, feathers and snake exuviae were used as bait. Twenty-five species of keratinophilic fungi were found in various types of water bodies. Hyphochytrium catenoides, Aphanomyces stellatus, Leptolegniella caudala and Achlya oligacantha represent new records as koratinophilic fungi.

Seventy five species of fungi were found in tbe Augustów Lakes. The following fungi unknown from Poland were rocorded: Rhizophydium pollinis-pini, Chytriomyces cosmarii, C. poculatus, Lageaidium humanum, Aphanomyces astaci, Leptolegeniella piligena, Achlya klebsiana, Cladolegnia unispora, Zoophagus pectosporus, Rhodosporidium toruloides and Vargamyces aguaticus.

Summary The ecology of the oyster pathogens Vibrio splendidus and Vibrio aestuarianus in the brackish aquatic environment was extensively investigated in this study. By conducting laboratory experiments under natural setting conditions, it was shown that V. splendidus LGP32 strain generally exhibits longer persistence in both seawater and sediment than V. aestuarianus 01/32 strain. Both strains maintained viability and culturability for longer times in the sediment, suggesting that this compartment may represent a suitable niche for their persistence in the environment. In addition, both strains attached to chitin particles and copepods, the efficiency of attachment being higher in V. splendidus than in V. aestuarianus. Similarly, LGP32 strain showed a greater capability to form biofilm on poly-vinyl chloride (PVC) surfaces than 01/32 strain. LGP32 and 01/32 strains were also capable of entering a viable but non-culturable state after extended incubation at 5°C, a condition commonly found during cold season in the aquatic brackish environment. These results are consistent with field data collected during a 2-year sampling campaign in the northern Adriatic Sea and provide background information on the mechanisms promoting V. splendidus and V. aestuarianus persistence in coastal water, thus contributing to a better understanding of the epidemiology of the associated diseases.

Many organisms seasonally modify their standard metabolic rates (SMR). However, the diversity of cues triggering the acclimatization response remains little understood. We examined the influence of experimentally induced aquatic-to-terrestrial habitat shift on the thermal sensitivity of SMR in newts. Standard metabolic rates increased with temperature (13-23°C), although consistently lower in terrestrial than aquatic individuals. Motor activity during respirometry trials decreased with temperature at similar rates in both groups. We conclude that in newts, a habitat shift might represent an important modulator of the seasonal acclimatization response in SMR. Lowered SMR suggests the potential to reduce newt maintenance costs and depletion of caloric reserves during the activity-limited period on land.

Two new species, Cephalaeschna cornifrons sp. nov. and C. ordopapiliones sp. nov. from Yunnan Province, China, are described, illustrated in color and compared with known Chinese Cephalaeschna. All the holotypes are deposited in the Collection of Aquatic Animals, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan City, Hubei Province, China. Brief notes on biology of each species are also provided.

Three new Cephalaeschna species, C. discolor sp. nov. (holotype male; Shennongjia National Nature Reserve, Shennongjia City, Hubei province, China, 16 August 2012), C. mattii sp. nov. (holotype male; Lujiahe River, Zigui County, Hubei province, China, 18 September 2012) and C. solitaria sp. nov. (holotype male; Dalongtan in Shennongjia National Nature Reserve, Shennongjia City, Hubei province, China, 19 July 2012) are described, illustrated in color and compared with the known Chinese Cephalaeschna. All the holotypes are deposited in the Collection of Aquatic Animals, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan City, Hubei Province, China. The hitherto unknown male of C. obversa and female of C. patrorum are also described and illustrated. Brief notes on biology of each species are also provided.

Changes in the distribution of rainfall and the occurrence of extreme rain events will alter the size and persistence of aquatic ecosystems. Such alterations may affect the structure of local aquatic communities in terms of species composition, and by altering species interactions. In many aquatic ecosystems, leaf litter sustains detrital food webs and could regulate the responses of communities to changes in rainfall. Few empirical studies have focused on how rainfall changes will affect aquatic communities and none have evaluated if basal resource diversity can increase resistance to such rainfall effects. In this study, we used water-holding terrestrial bromeliads, a tropical aquatic ecosystem, to test how predicted rainfall changes and litter diversity may affect community composition and trophic interactions. We used structural equation modeling to investigate the combined effects of rainfall changes and litter diversity on trophic interactions. We demonstrated that changes in rainfall disrupted trophic relationships, even though there were only minor direct effects on species abundance, richness, and community composition. Litter diversity was not able to reduce the impact of changes in rainfall on trophic interactions. We suggest that changes in rainfall can alter the way in which species interact with each other, decreasing the linkages among trophic groups. Such reductions in biotic interactions under climate change will have critical consequences for the functioning of tropical aquatic ecosystems.

Bacteria showing antimicrobial resistance (AMR) pose a significant global healthcare problem. Although many mechanisms conferring AMR are understood, the ecological processes facilitating its persistence and spread are less well characterised. Aquatic systems represent an important milieu for the environmental release, mixing, persistence and spread of AMR bacteria and resistance genes associated with horizontally transferable genetic elements. Additionally, owing to the use and discharge of antimicrobials and biocides, and the accumulation and abundance of other pollutants, mechanisms that confer AMR might evolve in aquatic systems. In this review, we hypothesise that aquatic systems have an important ecological and evolutionary role in driving the persistence, emergence and spread of AMR, which could have consequences when attempting to reduce its occurrence in clinical settings.

Many birds and mammals forage under water and have to return to the surface to breathe. Models of optimal diving attempt to explain the behaviour of such animals in terms of selection for successful foraging given the constraints imposed by physiology. Several recent papers have questioned the accuracy of both the assumptions and the predictions of these models. Here, I provide a critical review of these papers, arguing that they misrepresent both the models and the data. As a result, they focus on inappropriate tests. I use the debate to suggest various new models and to explore the general relationship between theory and data in behavioural ecology. In particular, I consider the merits of qualitative and quantitative predictions.

We examined responses of macroinvertebrate assemblages to environmental and temporal variations along spring source-spring brook transects in two fen habitats, sharply differing in groundwater chemistry, and compared the patterns among individual taxonomical groups. We hypothesised a different importance of environmental heterogeneity and seasonal changes primarily linked to strong tufa precipitation, which causes stronger environmental filtering in the calcareous fen. In concordance, we observed that assemblages of the more homogenous calcareous fen primarily changed over time, due to seasonal shifts in source availability and favourable conditions.

The effect of phosphorous enrichment on decomposition rate, exoenzymatic activities (β-glucosidase, cellobiohydrolase and alkaline phosphatase), and macroinvertebrate abundance in Typha latifolia leaves were assessed in a 2nd order Pampean stream (Central Argentina). Phosphorous was added to a downstream reach while another reach located upstream was kept intact and, once significant differences in phosphorus concentration in water were attained, leaf bags were attached to each reach bottom. T. latifolia leaves lost 77% of their initial weight along 154 days and decomposition rates were not significantly different between reaches. Besides, neither exoenzymatic activities nor macroinvertebrate abundances differed between reaches. However, an increment in leaf phosphorus content, attributed to immobilization by decomposer microorganisms, was detected in the enriched reach.

We studied the diet of 50 individuals of Hyalella sp. collected in the karstic headwaters of a high-altitude Andean river (3817 m a.s.l. Peru) in four different habitats: macrophytes, bryophytes, leaf litter, and layers of travertine. The gut content analysis showed a dominance of fine particulate organic matter (FPOM) in most habitats – layers of travertine (69.5%), Myriophylum (58.5%) and bryophytes (56.8%) – except for individuals collected in leaf litter where coarse particulate organic matter (CPOM) represented 68% of gut content, which indicates a high trophic flexibility of Hyalella sp. Likewise, in an experiment with feeding chambers in situ during three days, twenty individuals of Hyalella sp. presented a higher consumption of leaf litter of native species (Polylepis sp.) (0.025 mg/day) than those of an introduced species (Eucalyptus globulus) (0.008 mg/day). (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The ai m of this study was to examine the combined effect of water transparency and narrow macrophyte belts on zooplankton assemblages in two oxbow lakes (Krapina River, Croatia). Samples were collected in open water and among helophytes in the littoral zone from April until September 2008. Rotifers were the most abundant group of zooplankton in both lakes, and dominated in the Krapina oxbow lake 1 (KO1). Lake KO1 had significantly lower transparency, lower percentage macrophyte cover and higher chlorophyll a concentration than Krapina oxbow lake 2 (KO2). In lake KO1, variation in the horizontal distribution of cladocerans and rotifers in terms of their abundance seemed to be determined by competition between Bosmina longirostris and Keratella cochlearis, initiated by oscillation in transparency and detritus availability. In lake KO2, with higher transparency and higher percentage macrophyte cover, the abundance of small- and large-bodied cladocerans increased in the littoral zone simultaneously with higher transparency, suggesting fish predation. Results of this study indicated that small differences in transparencies between the two lakes caused significant differences in horizontal distribution of the zooplankton assemblage. Even narrow helophyte belts offered a refuge to zooplankton, although lower transparencies reduced the effectiveness of macrophytes as a refuge from predators.

We quantified interactive effects of human activities and ionic composition on algal community patterns. The work was done in ten urban clay-pit ponds within the vicinity of Vienna (Austria), characterized by gradients of clay-rich geological deposits and different trophic states caused by multiple sources of anthropogenic stress like nutrient input, swimming or shoreline destruction. A total number of 397 algal taxa were found with some halotolerant species occurring in high abundance like the diatom taxa Entomoneis paludosa, Chaetoceros muelleri, Navicula halophila or the rare Gyrosigma parkerii. Halophil and halotolerant taxa were insensitive to eutrophication. Although the ponds showed on average only moderately elevated electric conductivities (1833 ± 580 (SD) μS cm -1 ), taxa number were negatively related to ion concentration. SO 4 2- and HCO 3 - were the most important anions, with SO 4 -2 dominating at most sites. Ca 2+ was the major cation in six ponds; four more had Ca 2+ and Na + as co-dominant cations. The Viennese sites experienced higher nutrient loadings than the ponds located in Lower Austria. Cluster analysis revealed eight significant groups which represented both spatial and temporal differences among individual ponds. For these groups 32 indicator species were defined. With only two exceptions no halophil nor halotolerant taxa were found as indicator species because these were highly abundant in all investigated ponds. Canonical correspondence analysis showed a strong spatial separation of the ponds with 20 % of the species variation being explained by environmental variables. Variance partitioning revealed the composite variables eutrophication as a function of anthropogenic pressure and ion concentration of equal importance for species variability data.

Planktivorous fish are known to affect the zooplankton community both in terms of species composition and species specific morphological traits. Remains of cladocerans are deposited as microfossils ...

We examined the life history, annual production, diet, habitat preferences and competition of two species of stoneflies Notoperla fasciata and N. magnaspina in a Patagonian mountain headwater stream. Benthic samples and adult collections were taken monthly from July 2004 to June 2005. A habitat selection study was performed concurrently during high and low water periods in five substrate types. Although both species showed long life cycles (N. fasciata: 20 months and N. magnaspina: 3 years) their life histories and temporal dynamics were different. Growth was rapid during summer and early autumn as a result of warmer temperatures but N. magnaspina had a shorter emergence period (November to January) than N. fasciata (January to April). N. fasciata was the dominant Notoperla species with a mean annual density 6 times higher and secondary production 4.5 higher than that of N magnaspina. While boulders in riffles and pools, and leaf-pack habitats supported significantly more individuals of N. magnaspina in the low water period (ANOVA, p 0.26). N. fasciata dominated in the high water period and N. magnaspina during the low water period. Analysis of gut contents revealed that both species were herbivorous grazers, and consumed the same food types. The interspecific overlap in density, biomass and annual production among habitat types was high in the low water period (PS> 0.5). However, N. fasciata were smaller than N. magnaspina. The existence of different life history strategies and the temporal shift of main generations and density peaks were critical to allow species coexistence and to reduce competition.

We investigated the effect of weather and hydrological variables on the phosphorus concentration in a large, shallow lake, Laguna Chascomus. Total phosphorus (TP) concentrations were high (609.0 ± 196.0 μg L ―1 ) and within the range typical of hypertrophic lakes. TP showed a bimodal seasonal pattern with maxima occurring near spring and fall equinoxes, and the minima around winter and summer solstices. The bulk of TP ( > 80 %) corresponded to the particulate fraction (i.e., seston). We used data collected during the period 2005―2007 to develop regression models of particulate phosphorus (Ppart) vs. weather and hydrological variables, i.e., incident solar radiation (I 0 ), wind speed (W), mean depth (Z) and water temperature (T). The parameterized models were subsequently used to predict the Ppart concentrations for the 2008 dataset. For developing the first model we took the standard approach of regressing Ppart vs. the independent variables. An alternative to the standard approach was suggested by previous findings from an outdoor experiment demonstrating that increases in incident light resulted in higher seston concentrations, but higher light levels also resulted in lower sestonic P content (Ppart / seston). Thus, for developing the second model we regressed (i) the concentration of seston and (ii) the sestonic P content vs. weather variables, and subsequently calculated Ppart as the product of these two estimates. When confronted against data collected on 2008, the first model failed to explain any significant proportion of the total variance in Ppart (R 2 = 0.05, p = 0.28, n = 24), while the second model accounted for 32 % of the variance in Ppart (R 2 = 0.32, p = 0.004, n = 24). We suggest that the opposite seasonal trends of seston and Ppart / seston provide a plausible mechanism for explaining the bimodal seasonal pattern of TP observed in this hypertrophic shallow lake.

The leech Dina punctata Johanson, 1927 inhabits various types of running waters. This species appeared in Slovakia probably after the first Rhine-Main-Danube canal was built. Because little is known about its ecology, the aim of our study was to analyze the life cycle, individual growth rate, reproduction parameters and food composition of D. punctata in the Vydrica Stream. Samples of leeches were taken mainly each month from April 2003 to November 2004. The leech D. punctata had maximal 2-year life cycle there. Mature leeches, which were recognized by the presence of clitella, were present from April to the end of August. The most individuals mature at the age of 1 year. The breeding season of D. punctata peaks in June. The number of eggs per one cocoon is from 3 to 12. The mean successfulness of development of egg to embryo is 58%. Larvae from the family Chironomidae (28%), Gammarus fossarum (20%) and oligochaetes from the subfamily Naidinae (17%) are the dominant components of the feeding niche. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The aim of the study was to estimate the influence of environmental conditions resulting from coal mining on the diversity of bottom oligochaete communities in subsidence ponds. In the ponds studied 17 oligochaete species representing the families Lumbriculidae (1 species), Enchytraeidae (1 species) and Naididae (15 species), in the new sense (Erseus et al., 2008) were collected. The presence of Aulodrilus japonicus Yamaguchi, 1953 and Potamothrix bavaricus (Oschmann, 1913), rare species in anthropogenic water bodies, is noteworthy. Canonical correspondence analysis (CCA) showed that the important factors influencing oligochaete distribution in the subsidence ponds studied were the type of substratum, the organic matter content of the sediment as well as the mineralization of the water. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Two rivers in Norway were treated with rotenone in an effort to eradicate the salmon parasite, Gyrodactylus salaris. Rotenone induced an immediate catastrophic invertebrate drift, mainly of dead individuals. The response to rotenone with respect to degree and timing varied widely. Baetis rhodani, Isoperla sp. and Rhyacophila nubila displayed a strong increase in drift densities early in the treatment. Baetis niger, Ameletus inopinatus, Heptagenia sp. and Agapetusochripes showed a delayed response. Ephemerella aurivillii, E. mucronata, Taeniopteryx nebulosa and Elmis aenea drifted at low densities throughout the treatment. Early larval instar tended to be more sensitive to rotenone than later instar, and the toxic effect of rotenone tended to increase with increasing water temperature. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Zoosporic true fungi and heterotrophic straminipiles are phylogenetically unrelated groups of microorganisms playing similar ecological roles in food webs in fresh water ecosystems. As saprotrophs they are important decomposers of organic matter of animal and vegetal origin. However, there is still little research on most aspects of the ecology of these microorganisms. In this study the species composition of zoosporic true fungi (Blastocladiomycota and Chytridiomycota) and heterotrophic straminipiles (Hyphochytriomycota and Peronosporomycota), and their frequency, abundance and diversity on different types of baits were analyzed. Samples for characterizing the species composition were collected over a four-year period and for characterizing the structure of the assemblages at four dates during a one-year period. The relationship between some biological and environmental parameters were analysed. We expected that fluctuations in environmental factors during the year might lead to changes in the species composition and structure of the assemblages. Sixty-eight taxa were recovered with the baiting technique during the four-year period. The species composition was dependent primarily on the type of bait used. The structure of the assemblages also appeared to be more influenced by the type of baits available for colonization than by other environmental parameters. Even though the abundance of the taxa was associated with pH, nitrite, sulfate, soluble reactive phosphorous and dissolved oxygen concentrations. We did not find any differences in their richness, frequency, abundance and diversity during the year as expected.

The distribution of charophyte vegetation in 57 ponds located in the basin of the River Duero in North-Western Spain was studied in relation to eutrophication. A total of 11 charophyte taxa were recorded in 40 ponds. However, only Chara fragilis Desv., Chara connivens Salzm. ex A. Braun and Nitella translucens (Pers.) C. Agardh were found in more than 17% of the ponds where charophytes occurred. Significant differences between ponds with and without charophytes were found for the following parameters: volatile suspended solids (VSS), total suspended solids (TSS), turbidity, chlorophyll-a, nitrate and total phosphorus (TP). These variables were significantly lower in ponds where charophytes were present. Charophytes were found over a wide range of TP concentrations (20―6884 μg L ―1 ). However, taxa showed differing sensitivities to phosphorus concentrations. Thus, Chara connivens and Chara fragilis showed the highest optimum values for TP concentration (1875 and 551 μg L ―1 TP, respectively) while Nitella translucens registered the lowest optimum value for TP (69 μg L ―1 ). The charophyte cover showed a significant negative correlation with VSS and chlorophyll-a. As for charophyte taxa, Chara connivens cover was positive and significantly correlated with orthophosphate (SRP), while Nitella translucens cover showed a significant negative correlation with TP and TSS. The ordination of charophyte taxa showed a principal gradient of mineralization and ecological condition and a secondary gradient of eutrophication.

The aim of this study was to quantify and qualify seasonal changes of all important components of a microbial biofilm community. We explored the development of the biofilm community structure on submerged glass slides for 15 months including all organisms from bacteria to macro-invertebrates. Besides bacteria, heterotrophic flagellates were the most abundant biofilm component followed by ciliates, meiofauna organisms and algae. Most important were sessile choanoflagellates, peritrichous ciliates and some crustaceans. Ciliates and macrofauna were the most important components with regard to the total biovolume. The biofilm architecture was strongly influenced by extracellular structures produced by protozoans and macro-invertebrates. Alterations within the biofilm community were mainly due to changes in abundances rather than in the composition except for heterotrophic flagellates and macroinvertebrates. Biofilm organisms were dominated by planktivorous organisms exerting a strong grazing impact on the plankton organisms in this large river.

The contribution of shredders to litter breakdown in a tropical stream in Hong Kong was investigated by using coarse- and fine-mesh bags to include or exclude large macroinvertebrates. Three native species, plus a mixture of all of them, were used to examine the effects of leaf type and species composition on breakdown. A well-studied temperate species, Alnus glutinosa, was included to benchmark breakdown rates in Hong Kong with counterpart streams outside the tropics. Shredders constituted 13% of macroinvertebrates in coarse-mesh bags but were virtually absent from fine-mesh bags. However, abundance of macroinvertebrates (especially chironomids) in fine-mesh bags was almost twice that in coarse-mesh bags. Despite interspecific differences, litter breakdown rates were consistently faster in coarse-mesh bags, indicating a probable effect of shredders, although current velocity also influenced breakdown of one native species. Alnus glutinosa breakdown rates were within the range reported in temperate streams. The litter mixture broke down at a rate approximately equal to the mean of the constituent species and non-additive compositional effects (indicative of biodiversity-ecosystem functioning relationships) were not apparent. Litter breakdown in fine-mesh bags was rapid relative to rates reported from temperate streams, despite the exclusion of shredders. Evidently, non-shredding macroinvertebrates and microbes played a significant role in litter breakdown in Hong Kong.

Leaf litter can be an important food resource in small forest streams, but its availability to detritivorous macroinvertebrates depends on stream retentiveness. Previous work in Hong Kong streams revealed a scarcity of large detritivores, and it is possible that this reflects the availability or instability of litter resources. Using leaf analogues made from waterproof paper, we undertook short-term experiments to measure the retentiveness of eight Hong Kong streams under baseflow conditions during the dry season; four streams had coarse bed sediments (boulder dominated) and four had relatively fine sediments (cobble-gravel dominated). Initially we compared the transport properties of soaked and unsoaked leaf analogues with the leaves of four native trees in one of the streams. Soaked and unsoaked analogues were used to mimic waterlogged and newly-fallen leaves. Mean travel distances (S p ) of leaves and analogues in the study streams ranged from 1-22 m. These are comparable to values recorded from similar-sized streams in temperate latitudes. Unsoaked analogues traveled further (mean S p = 10.2 m versus 3.1 m) than soaked analogues in all study streams, but retention behaviour of analogues generally matched that of real leaves. Mean travel distances of both analogue types were unrelated to streambed sediment size or sediment heterogeneity, but travel distance of soaked analogues was positively related to stream discharge. Litter retention remained high over a six-day period in one of the streams, suggesting that litter would be readily available to detritivores during periods with stable discharge, and that the scarcity of shredders must be caused by other factors.

Spatial and temporal variation in invertebrate drift during in-stream gravel extraction in a gravel-bed river in south western Slovenia (SE Europe) was investigated. Drift samples were collected at three sites (an upstream control site and two downstream impacted sites) on the first and third days of gravel extraction. Drift measured during gravel extraction was compared to the hyporheic invertebrate community at the site of gravel extraction. Significant differences in drift were observed between the sites (ANOVA, n = 18, F = 23.29, p

Drifting invertebrates from small headwater streams are a food subsidy for fishes and other downstream consumers in larger streams. This subsidy can become especially important for stream fishes during summer due to high metabolic demand caused by elevated water temperatures. The source length in small streams contributing these drifting invertebrates to fish bearing habitat has not been established. We conducted an experiment to determine if summer drift delivered by headwater streams to larger channels is influenced by contributions originating more than 100 m upstream. We conducted this experiment on tributaries of the Calapooia River, Oregon, USA. We blocked drift with 250 μm mesh nets in three streams 100 m upstream of our sample nets continuously for 48 d. We also sampled five streams without blocking nets. Four 24 h samples of drift were collected prior to the placement of blocking nets and every two weeks afterwards at each stream. Overall mean abundance and mean biomass of drift did not differ between blocked and unblocked streams for any sampling period. There was a temporal trend at all sites of declining invertebrate abundance and biomass. We found no treatment effect for any of the most common insect orders or for the 16 genera that comprised at least 1% of the total organisms captured. The majority of invertebrate drift is of local origin in headwater streams during summer baseflow.

The Gemenc floodplain of the Danube possesses numerous side arms and backwaters. The aim of my study was to explore connections between hydrological events and diversity patterns of the planktonic rotifer assemblages of these water bodies. During the study period (2002–2008) 75 taxa of rotifers were found. Generally, the water bodies of the floodplain had more diverse rotifer assemblages than the main arm. At low and medium water levels diversity was highest in the parapotamal water bodies. This result may be explained by the intermediate disturbance hypothesis. At high water levels the highest biodiversities shifted to the plesiopotamal. Biodiversity, dominance, and evenness correlated with water flow and temperature. Patterns of biodiversity seem to be determined by the water level of the main arm; therefore the water regime appears to provide pronounced temporal variability in the hydro-ecology of the floodplain. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)