Search results for "phytoplankton"

Diversity and Distribution of the Dinoflagellates Brachidinium, Asterodinium and Microceratium (Brachidiniales, Dinophyceae) in the open Mediterranea…

2011

Diversity and Distribution of the DinoflagellatesBrachidinium, AsterodiniumandMicroceratium(Brachidiniales, Dinophyceae) in the open Mediterranean SeaBrachidiniacean dinoflagellates have been investigated in the open waters of the Mediterranean Sea, along a transect from the south of France to the south of Cyprus (20 June-18 July 2008).BrachidiniumandKarenia papilionaceaoften co-occurred,B. capitatumpredominating in the surface waters. The highest abundance ofBrachidiniumwere found in the upper 25min the western Mediterranean with amaximum (24 cells L-1) at a depth of 5 m in the Balearic Sea.Asterodinium(up to 4 cells L-1) was recorded below of deep chlorophyll maxima. The genusMicroceratiu…

That twenty years is nothing for gravel-pit limnology

2020

[EN] The past twenty years have witnessed a rise in the analysis of long-term limnological data given the need to know whether global warming is affecting freshwaters, and if so, how. Previous studies indicated that processes affecting ecosystem function-ing may develop slowly, thus requiring long-term study, as in the case of the eutrophication-oligotrophication gradient. Here we report annual averages and seasonal variability of meteorological data (air temperature, solar radiation, rainfall) and the main limnological variables (lake level, water temperature, euphotic depth, mixing depth, nitrogen and phosphorus compounds and phytoplankton biomass) for a gravel-pit, seepage lake close to …

Metagenomes of Mediterranean Coastal Lagoons

2012

Coastal lagoons, both hypersaline and freshwater, are common, but still understudied ecosystems. We describe, for the first time, using high throughput sequencing, the extant microbiota of two large and representative Mediterranean coastal lagoons, the hypersaline Mar Menor, and the freshwater Albufera de Valencia, both located on the south eastern coast of Spain. We show there are considerable differences in the microbiota of both lagoons, in comparison to other marine and freshwater habitats. Importantly, a novel uncultured sulfur oxidizing Alphaproteobacteria was found to dominate bacterioplankton in the hypersaline Mar Menor. Also, in the latter prokaryotic cyanobacteria were almost exc…

Impact on the water column biogeochemistry of a Mediterranean mussel and fish farm

2002

We investigated and compared the impact of organic loads due to the biodeposition of mussel and fish farms on the water column of a coastal area of the Tyrrhenian Sea (Western Mediterranean). Physico-chemical data (including oxygen, nutrients, DOC and particulate organic matter), microbial variables (picoplankton and picophytoplankton density and biomass) and phytoplankton biomass (as chlorophyll-a) were determined on a monthly basis from March 1997 to February 1998. The results of this study indicate that both fish farm and mussel culture did not alter significantly dissolved inorganic phosphorus and chlorophyll-a values, while inorganic nitrogen concentrations were higher in mussel farm a…

Structure of planktonic microbial communities along a trophic gradient in lakes of Byers Peninsula, South Shetland Islands

2013

AbstractA systematic limnological survey of water bodies of Byers Peninsula (Livingston Island, South Shetland Islands) was carried out during the summer of 2001/02. Abundances of microbial plankton were determined which allowed a delineation of the pelagic food web structure. We also report the nutrient status of these lakes. We demonstrate the occurrence of a trophic gradient that extended from upland lakes (oligotrophic) to the coastal ones (eutrophic). The study shows that a lake's morphology regulates the relative importance of the pelagic and benthic habitats, whereas nutrient loads mainly determine its trophic status. Yet, some of the variability observed could be also a legacy of th…

2020

The composition of phytoplankton community is the basis for environmental monitoring and assessment of the ecological status of aquatic ecosystems. Community composition studies of phytoplankton have been based on time-consuming and expertise-demanding light microscopy analyses. Molecular methods have the potential to replace microscopy, but the high copy number variation of ribosomal genes and the lack of universal primers for simultaneous amplification of prokaryotic and eukaryotic genes complicate data interpretation. In this study, we used our previously developed directional primer-independent high-throughput sequencing (HTS) approach to analyze 16S and 18S rRNA community structures. C…

Inferring the Relative Resilience of Alternative States

2013

Ecological systems may occur in alternative states that differ in ecological structures, functions and processes. Resilience is the measure of disturbance an ecological system can absorb before changing states. However, how the intrinsic structures and processes of systems that characterize their states affects their resilience remains unclear. We analyzed time series of phytoplankton communities at three sites in a floodplain in central Spain to assess the dominant frequencies or "temporal scales" in community dynamics and compared the patterns between a wet and a dry alternative state. The identified frequencies and cross-scale structures are expected to arise from positive feedbacks that…

Multivariate-Analysis of Phytoplankton and Related Environmental-Factors, in a Shallow Hypertrophic Lake

1995

Data on some relevant environmental variables and phytoplankton species composition, collected from the hypertrophic shallow lake Albufera of Valencia (Spain) during 1980-88, were examined using Redundancy Analysis (RDA). The hydrological cycle of the lake is manipulated for rice cultivation in the area. Seasonality and the particular hydrological cycle of the lake were the principal factors influencing long-term phytoplankton dynamics. Annual or horizontal differences were less important than the seasonal factor. However, a trend of phosphate increase and underwater illumination decrease was observed between 1980 and 1988. These changes might be related to some species year-to-year variati…

DifferingDaphnia magnaassimilation efficiencies for terrestrial, bacterial, and algal carbon and fatty acids

2014

There is considerable interest in the pathways by which carbon and growth-limiting elemental and biochemical nutrients are supplied to upper trophic levels. Fatty acids and sterols are among the most important molecules transferred across the plant-animal interface of food webs. In lake ecosystems, in addition to phytoplankton, bacteria and terrestrial organic matter are potential trophic resources for zooplankton, especially in those receiving high terrestrial organic matter inputs. We therefore tested carbon, nitrogen, and fatty acid assimilation by the crustacean Daphnia magna when consuming these resources. We fed Daphnia with monospecific diets of high-quality (Cryptomonas marssonii) a…

Phytoplankton strategies and diversity under different nutrient levels and planktivorous fish densities in a shallow Mediterranean lake

2005

Two mesocosm experiments were carried out to investigate the dynamic effects of nutrients (nitrogen and phosphorus) and planktivorous fish additions on phytoplankton strategies and diversity. The phylogenetic and functional approaches were used to understand phytoplankton ecology in shallow Mediterranean lakes. The experimental approach is new for the study of algal functional groups. Nutrient loading and fish stocks enhanced biomass of small algae but decreased phytoplankton diversity and species richness. Faster species replacement and fluctuations in diversity occurred above loadings of 1 μM P and 21 μM N. Mesotrophic conditions favoured a diverse pool of species, including nostocales an…