Search results for "phytoplankton"

Taxonomic identity and phytoplankton diet affect fatty acid composition of zooplankton in large lakes with differing dissolved organic carbon concent…

2015

An increase in loading of dissolved organic carbon (DOC) from terrestrial to freshwater ecosystems has recently been documented in several boreal regions. We studied how transfer of important biomolecules, fatty acids, may be connected to DOC in pelagic food webs of large boreal lakes. We collected nine zooplankton taxa during three seasons from six lakes along a gradient of DOC (5–10 mg C L−1). Taxonomic identity explained 62% of the variation in zooplankton fatty acids, while the effects of DOC and season were less pronounced. This suggests that the community composition of zooplankton is important in determining the quality of food available for higher trophic level consumers. Seasonal d…

Diet-specific biomarkers show that high-quality phytoplankton fuels herbivorous zooplankton in large boreal lakes

2014

SUMMARY 1. The zooplankton is a key link in the transfer of energy from primary producers up through aquatic food webs. Previous efforts to quantify the importance of basal resources to aquatic consumers have used stable isotopes (SI) and simple ternary models, including only ‘bulk’ phytoplankton, bacteria or terrestrial particulate organic matter (t-POM). 2. We used a novel Bayesian mixing model based on fatty acids (FA) to quantify the dietary assimilation of seven basal resources, including five phytoplankton groups, pelagic bacteria and t-POM, to Cladocera in large boreal lakes in Finland. To account for trophic enrichment of FA from the diet to consumers, we parameterised the model wit…

Effects of the filter-feeding benthic bivalve corbicula fluminea on plankton community and water quality in aquatic ecosystems: A mesocosm study

2021

The influence of filter-feeding bivalves on plankton communities, nutrients, and water quality in a given aquatic ecosystem is so profound that they can be considered ecosystem engineers. In a 70-day mesocosm experiment, we tested the hypothesis that Corbicula fluminea would change plankton community structure by reducing small zooplankton and large phytoplankton and improve water quality by reducing nutrients. We monitored levels of nitrogen and phosphorus, organic suspended solids (OSS), and light at the sediment surface. Within the plankton, phytoplankton biomass (as Chl a, &gt

Lake restoration influences nutritional quality of algae and consequently Daphnia biomass

2020

AbstractFood quality is one of the key factors influencing zooplankton population dynamics. Eutrophication drives phytoplankton communities toward the dominance of cyanobacteria, which means a decrease in the availability of sterols and long-chain polyunsaturated fatty acids (EPA and DHA). The effects of different restoration measures on the nutritional quality of the phytoplankton community and subsequent impacts on zooplankton biomass have rarely been considered. We analyzed the nutritional quality of phytoplankton in the eutrophic Lake Vesijärvi in southern Finland over a 37-year period, and studied the impacts of two restoration measures, biomanipulation and hypolimnetic aeration, on th…

Arctic sea ice algae differ markedly from phytoplankton in their ecophysiological characteristics

2021

Photophysiological and biochemical characteristics were investigated in natural communities of Arctic sea ice algae and phytoplankton to understand their respective responses towards variable irradiance and nutrient regimes. This study revealed large differences in photosynthetic efficiency and capacity between the 2 types of algal assemblages. Sea ice algal assemblages clearly displayed increased photoprotective energy dissipation under the highest daily average irradiance levels (>8 µmol photons m-2 s-1). In contrast, phytoplankton assemblages were generally light-limited within the same irradiance ranges. Furthermore, phytoplankton assemblages exhibited more efficient carbon assimilat…

Osmotrophic glucose and leucine assimilation and its impact on EPA and DHA content in algae

2020

The uptake of dissolved organic compounds, that is, osmotrophy, has been shown to be an efficient nutritional strategy for algae. However, this mode of nutrition may affect the biochemical composition, for example, the fatty acid (FA) contents, of algal cells. This study focused on the osmotrophic assimilation of glucose and leucine by selected seven algal strains belonging to chlorophytes, chrysophytes, cryptophytes, dinoflagellates and euglenoids. Our laboratory experiments with stable isotope labeling showed that osmotrophy occurred in four of the selected seven strains. However, only three of these produced long chain omega-3 FAs eicosapentaenoic acid (EPA; 20:5ω3) and docosahexaenoic a…

Small pelagic fish in the new millennium: A bottom-up view of global research effort

2021

The present review is an outcome of discussions at the ICES-PICES Symposium on Drivers of Dynamics of Small Pelagic Fish convened in Victoria, B.C., Canada in spring 2017.-- This review is a first contribution of a new international Working Group on Small Pelagic Fish started jointly by ICES (WGSPF) and PICES (WG43) to continue world-wide collaboration to advance knowledge on the drivers of populations of SPF.

How to reach optimal estimates of confidence intervals in microscopic counting of phytoplankton?

2021

Abstract Present practices in the microscopic counting of phytoplankton to estimate the reliability of results rely on the assumption of a random distribution of taxa in sample preparations. In contrast to that and in agreement with the literature, we show that aggregated distribution is common and can lead to over-optimistic confidence intervals, if estimated according to the shortcut procedure of Lund et al. based on the number of counted cells. We found a good linear correlation between the distribution independent confidence intervals for medians and those for parametric statistics so that 95% confidence intervals can be approximated by using a correction factor of 1.4. Instead, the rec…

Editorial: Changing Plankton Communities: Causes, Effects and Consequences

2019

Eutrophication and browning influence Daphnia nutritional ecology

2019

Climate change and land-use practices can enhance lake eutrophication and browning, which influence phytoplankton composition by decreasing the availability of food high in nutritional quality (algae) and increasing the abundance of low-quality food (terrestrial detritus, bacteria) for herbivorous zooplankton. Nutritionally valuable algae for zooplankton are rich in essential biomolecules such as amino acids, polyunsaturated fatty acids (PUFAs), sterols, and phosphorus. We performed laboratory experiments and showed a stronger positive relationship between zooplankton (Daphnia) cumulative offspring number and availability of high-quality algae (Cryptophytes: Rhodomonas/Cryptomonas; and Chry…