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We found that the phytoplankton's carotenoids in a small shallow lake correlate with nitrate-nitrogen. We also show that primary production and the nitrate content can be in stoichiometric relation. The results of the present study provide some materials on nitrogen limitation of freshwater aquatic systems.
The longitudinal distribution (along the stream) is more important than the temporal variation (along the seasons) to explain the variations of the composition of Thichoptera species in streams of the Brazilian Cerrado.
The study was intended to investigate faunal diversity of Cladocera in Subansiri flood plain wetlands. This is the first kind of study to document cladoceran fauna from these non-explored habitats.
We focused on effects of environmental factors on macrophyte species richness using generalized linear models. No obvious pattern of factors was observed for particular water body types. Our study showed that macrophyte species richness is shaped by complexity of factors and necessity of targeting survey and further generalisation of results not only on one specific water body.
The study assesses the landings of three mollusc species in Tonle Sap. It demonstrates that the bivalve was abundant during dry season, while the gastropod Pila species was abundant during rainy season. The results indicate significant contributions of mollusc to ecology and people's livelihoods, and the population of the two groups being intensively harvested.
The concept of functional feeding groups was used to classify and model the seasonal variation of zooplankton functional groups in relation to environmental variables.
Zooplankton species were grouped into 8 functional groups that vary spatially and followed a predictable seasonal pattern.
Total nitrogen, total phosphorus, ammonium, chlorophyll-a and water transparency were the major factor influencing zooplankton community.
Top-down control of phytoplankton by zooplankton in Xiquanyan reservoir is not strong enough to produce negative effect.
Effect of nutrient enrichment on the growth of periphytic algae was studied deploying chemical diffusing substrates in the river Ganga at Varanasi, India. Results depicted seasonal and nutrient induced changes in the species composition of the periphytic algal community. The growth was primarily N-limited and showed secondary P-limitation.
Pristine streams of a Pannonian lowland mountain support high mayfly species richness with diverse assemblage structure, which contributes significantly to our knowledge of mayflies in South Eastern Europe. Moreover, records of symbiotic parasite Symbiocladius rhithrogenae (Zavrel, 1924) attached to nymphs of Rhithrogena group semicolorata, represent new data for species distribution and show that our knowledge of the Croatian chironomid fauna is still growing.
This study assessed the short-term succession of benthic diatom assemblages. Our results underscore the importance of diatom diversity in neotropical streams, and the relevance of small variations in environmental factors for the composition of the assemblages in a rainforest stream.
A small tropical catfish (Corydoras aeneus) was able to dampen the populations of different nematode species dwelling homogeneous sandy sediment in laboratory–controlled aquaria. This study contributes to better understand the ecological relevance of the fish-nematode trophic channel.
The increase in Scenedesmus obliquus density from 2.0 × 106 to 4.0 × 106 cells mL−1 decreased the magnitude of stimulatory effects of lower concentrations of OTC but enhanced that of inhibitory effects of high concentration of OTC on the survival, asexual reproduction and population growth of Brachionus calyciflorus. So did the decrease in algal density from 2.0 × 106 to 1.0 × 106 cells mL−1.
The seasonal variations influence water quality parameters on neotropical reservoir. The biochemical oxygen demand is controlled by the interaction between the layers of water and the seasons of the year. The fish farm in these places, when kept within the capacity of supporting of the environment, does not alter the quality of water.
CCA explained 57.4% of correlation between ostracod species and environmental variables when water temperature, redox potential, pH and electrical conductivity were the most effective factors on species. Species with wide tolerance ranges were found in variety of habitats and distributed more frequently in broader geographic ranges than other species.
Although most studies use the genus Daphnia to evaluate phenotypic plasticity in cladocerans, other genera might also respond to predator infochemicals. In this study fish infochemicals increased the size at primipara, clutch size, net reproductive rate and longevity in Daphnia and Moina. Conversely, Chaoborus infochemicals affected only the net reproductive rates and longevity of cladocerans. Non-daphniid cladocerans may display similar responses to Daphnia when exposed to predators. However, as Daphnia is usually underrepresented in tropical lakes, studying other genera might offer new insights into predator-prey relationships and food webs in lake ecosystems.
Very short water residence time in a reservoir and consequently high water dynamics therein prevent the occurrence of long-term oxygen deficiencies, which in turn enables the development of diverse and abundant benthic fauna even in a lower, relatively more limnetic zone of a reservoir.
In meromictic coastal lake separated from the sea stable isotope composition of mixolimnion varied due to ice formation in winter and evaporation in summer. From 2012 to 2016 desalination of mixolimnion and upper chemocline was observed. Monimolimnion has highest salinity and enriched isotope composition indicating lack of mixing with overlying water.
We used data on fossil algae to assess the beta-diversity in hemiboreal lakes in Latvia.
Results show that the algae turnover increases towards the present day.
Anthropogenic impact on the landscape and lakes were relatively minor before AD 1200.
We propose that the natural reference conditions of lakes are prior AD 1200.
The major mid Holocene climatic and environmental perturbation known as the “4.2 events” is captured in the sedimentary sequence of Omalos Mediterranean Temporary Pond (MTP) in Western Crete. The potential of MTPs in future climate and environmental reconstrunctions is emphasized.
Dunalliella salina and Isochrysis sp showed a greater influence on reproductive value of the rotifer Brachionus sp “Alvarado” strain, associated to higher lipid, carbohydrate, protein and pigment content. These results contribute to improve knowledge on the optimal culture conditions for this tropical rotifer. We analyzed toxic and trace elements in carp from fish ponds. Fish liver was the main target organ for accumulation of Cu, Se and Zn, and dorsal muscle for Sr and Li. Fish liver showed a decrease of a range of elements towards the end of season. Arsenic was uniformly distributed in fish organs showing potential to build up in edible parts.
The content of a traits database dedicated to phytoplankton taxa of temperate lakes is presented. This database is maintained since the 70’s and gathers more than 50 traits (functional, physiological, ecological and morphological) for more than 1200 taxa. It is released open access in in Zenodo (https://zenodo.org; DOI: 10.5281/zenodo.1164834) and also as supplementary material on the journal website.
Studies in five productive humic lakes of low fish pressure indicated that taxonomic groups of zooplankton are determined by a different set of environmental variables, which explains very low species richness of zooplankton. Due to sharp thermal gradient in the lakes biomass of herbivores is reduced which promotes development of phytoplankton.
K. quadrata with two, one and none posterior lateral spines (2PS, 1PS and 0PS) did not show any preference to food level. The 0PS morphotype had less fitness than 2PS. Despite the morphotype of rotifer parent, the major morphotype of offsprings was 2PS. Food level might affect the ratio of 2PS and 1PS offsprings reproduced by 0PS and 1PS rotifer parents.
Distribution of 14 Peracarida species (5 native and 9 alien) along entire course of the Sava River was established: only natives inhabited the upper third of Sava and aliens dominated the rest of the course. Artificial stony substrates act as stepping stones of invasion for alien peracarids and largely contribute to their success in large lowland rivers.
This is the first whole-community study of zooplankton communities in temporary saline lakes in Cyprus. Our results support that in these systems (a) salinity is a major driver of zooplankton community and (b) should be a key factor for typological considerations according to the WFD; (c) zooplankton should be considered as biological quality element.
Kairomone released by higher densities of Asplanchna increased significantly the level of sexual reproduction of parental B. angularis females which might help the preys avoid the predator in time instead of facing the enemy through defenses, and the intrinsic rate of population increase that might facilitate the coexistence of preys with predators.
We provide evidences that the performance of the invasive macrophyte Egeria densa is more associated with abiotic factors than herbivory in its native (Brazil) and introduced range (France), indicating that environmental variables are probably the main drivers of its success in different habitats.
Compared to values recorded before 1998 in 57 farms located in three French natural regions, the numbers of snail populations observed in 2016 and 2017 were significantly lower, with an overall decline rate of 30.8% for Galba truncatula and 38.6% for Omphiscola glabra over the past 20 years.
Regularly published works devoted to fish assemblage structures are constructed from three population parameters: species number, relative number or relative biomass. The last one is the most similar to the estimated by the relative caloric content of biomass (wet weight), i.e. the best indicator of the strength and importance of a population in nature.
Pascal Laffaille specially takes interest in and makes a significant contribution to explain or predict the response of fish populations and communities to anthropogenic disturbance. And meanwhile, his researches also concentrate on ecological consequences of the decline of fish diversity in aquatic ecosystems. The relevant studies provide much knowledge and basis for proposing management action plans in aquatic ecosystems.
Pascal Laffaille specializes in fish ecology and makes a significant contribution to explain or predict the response of fish populations and communities to anthropogenic disturbance. The relevant studies have provided key theoretical basis for proposing management action plans in aquatic ecosystems.
Climate change has the potential to modify ecological process and life aspects of the aquatic community in small-order streams. We evaluated and found changes in behavior and metabolism of Aegla longirostri at different temperatures (21 °C and 24 °C). Thus, the future increase temperature of the streams will impact the aeglid's populations.
Blooms of toxin-producing cyanobacteria affect abundances of small Cladocera and their algal diet. Small Cladocera show selectivity for small cryptophytes, diatoms and chlorophytes. High tolerance to cyanobacterial toxins and selective feeding allow to permanent co-existence of small Cladocera with cyanobacterial blooms.
Climate change is expected to cause significant changes to the hydrology of lakes, reservoirs and other wetlands. In particular, there will be an increase in the level of disturbance produced by water-level fluctuations. An unstructured grid, finite volume model has been used to simulate the water level of Aguelmam Sidi Ali Lake (Morocco), with observed field data being used for model calibration and validation. The different hydrological conditions regarding lake input and output data were tested and water depth was calculated using bathymetry to predict water-level fluctuations in the future. The results predict that the water-level will decrease continuously. The lake will be dried up in about 20 years if very dry conditions continue in the region. Finally, the main objective of this simulation method is to accelerate and facilitate of systems' behavior learning in the current and future situation.
We analyzed toxic and trace elements in carp from fish ponds. Fish liver was the main target organ for accumulation of Cu, Se and Zn, and dorsal muscle for Sr and Li. Fish liver showed a decrease of a range of elements towards the end of season. Arsenic was uniformly distributed in fish organs showing potential to build up in edible parts.
This study showed that, in absence of nutrient limitation, some variables such as temperature are relevant to all organization levels, whereas some others like light availability have an effect on temporal distribution patterns of the dominant species.
Water temperature plays a primary role in controlling a wide range of physical, geochemical and ecological processes in lakes, with considerable influences on lake water quality and ecosystem functioning. In this work, we report on the ability of the one-dimensional lake model to simulate the water temperature of Moroccan Lakes, affected by climate change for the first time. During the study periods, two variables are studied, the epilimnion and metalimnion temperatures. The results show good agreement with water temperature observations that suggests that the predictive model can be used to obtain a first-order estimation of water temperature in Moroccan Lakes. Hence, it is possible to apply this model in other Moroccan Lakes to simulate the behavior of temperature and to investigate the potential future warming of the water column in Lakes, affected by climate change.
Our research concerns functioning of the river-lake system through an analysis of factors affecting the assimilation of biogenes and metals by aquatic plants typical for such a system. The greatest effect on the accumulation of an excessive amount of substances like nutrients and heavy metals occurring in the water ecosystem of the river and lake system seems to be demonstrated by the properties of the bottom sediments, mainly their granulometric composition. On the other hand, it was demonstrated that aquatic plants can have an effect on the fraction size in sediments, particularly near the outlet of the river to the water body.The obtained results could contribute to the creation of controlled conditions favouring contamination capture, which could a ffect the advancement of knowledge concerning the functioning of freshwater aquatic ecosystems.
