Search results for "plank"
showing 10 items of 578 documents
Plankton Tracker: A novel integrated system to investigate the dynamic sinking behavior in phytoplankton
2020
Abstract Phytoplankton sinking is an important property that can determine community composition, affecting nutrient and light absorption in the photic zone, and influencing biogeochemical cycling via material loss to the deep ocean. To date, the difficulty in exploring the sinking processes is partly due to methodological limitations in measuring phytoplankton sinking rate. However, in the last decade, works have illustrated various methods based on some non-invasive and low perturbing approaches (laser scanner, video-microscopy, fluorescence spectroscopy). In this study, we review the methods for sinking rate estimation and describe the Plankton Tracker, a novel integrated system to inves…
Database of diazotrophs in global ocean: abundance, biomass and nitrogen fixation rates
2012
Marine N<sub>2</sub> fixing microorganisms, termed diazotrophs, are a key functional group in marine pelagic ecosystems. The biological fixation of dinitrogen (N<sub>2</sub>) to bioavailable nitrogen provides an important new source of nitrogen for pelagic marine ecosystems and influences primary productivity and organic matter export to the deep ocean. As one of a series of efforts to collect biomass and rates specific to different phytoplankton functional groups, we have constructed a database on diazotrophic organisms in the global pelagic upper ocean by compiling about 12 000 direct field measurements of cyanobacterial diazotroph abundances (based on microscopic …
Benthic mats offer a potential subsidy to pelagic consumers in tundra pond food webs
2014
We quantified the potential nutritional contribution of benthic mats to pelagic consumers in tundra ponds using three approaches. (1) We compared benthic and pelagic habitats based on their algal biomass and community composition and assessed the dietary quality in terms of fatty acid (FA) concentrations in both habitats. The algal community compositions differed significantly between habitats. Both benthic and pelagic habitats contained saturated and unsaturated FAs, but on average there were more FAs relative to carbon in the pelagic habitat (44 6 29 m gm g C21) than the benthic habitat (23 6 18 m gm g C21) across all studied ponds. (2) We quantified the contribution of benthic mats to th…
Development of picoplankton during natural and enhanced mixing under late-winter ice
2014
We studied the development of autotrophic picophytoplankton and heterotrophic bacterioplankton during the tran- sition from winter ice cover to open water under natural and manipulated mixing conditions in eutrophic Lake Vesijarvi. During the melting of the snow and ice cover, a convection layer developed which eventually met the che- mocline at the interface between the oxic and anoxic water masses. However, in the years with mechanically enhanced mixing, the whole water column remained well oxygenated and the deepening of penetrative convection was facilitated. Stochastic variations in weather, primarily the thickness of the snow cover, likely determined the timing of picophytoplankton gr…
Assessing the effect of emergent vegetation in a surface-flow constructed wetland on eutrophication reversion and biodiversity enhancement
2018
Abstract A free water-surface constructed wetland (F4-unit) was created in a Mediterranean protected site to treat eutrophic inflows to the Albufera de Valencia lagoon, and enhance biodiversity. In 2013, the F4-unit was divided into three subunits and planted with different compositions of emergent macrophytes (Phragmites australis, Iris pseudacorus, and a mixture of several macrophytes: F4-Reed, F4-Iris and F4-Mixed subunits). Two nine-month periods were monitored after planting, and water quality variables were measured in the inflows and outflows. Waterfowl occupation and plankton biomass were analyzed to evaluate their role in eutrophication reversion. The low removal efficiencies relat…
Long-Term Phytoplankton Dynamics in a Complex Temporal Realm
2019
AbstractFaced with an environment of accelerated change, the long-term dynamics of biotic communities can be approached to build a consistent and causal picture of the communities’ life. We have undertaken a 25-year monthly-sampling study on the phytoplankton of a meso-oligotrophic lake, paying attention to controlling factors of overall biomass (TB) and taxonomical group biomass (TGBs). Long-term series included decreased trends of TB and TGBs, and multi-scale periodicity. A decadal TB periodicity emerged related to nitrogen concentration and Cryptophytes. Annual periodicities were mainly related to air and water temperature controlling the abundance of Chlorophytes or Dinoflagellates. Int…
Zooplankton abundance: A neglected key element in the evaluation of reservoir water quality
2018
Abstract Based on our results, we propose the use of zooplankton abundance (density or biomass) as an indicator to complement the information currently being used concerning the quality of water in reservoirs. Until now, the Water Framework Directive (EU) for lakes and reservoirs has not included zooplankton because the classification of the water trophic state is based on a bottom-up model: an increase in nutrients implies an increase in primary producers and, therefore, poorer water quality. The use of zooplankton has recently been claimed due to their sensitivity to environmental changes and their control over primary producers. From our work, carried out from 2006 to 2009 (summer and wi…
Influence of biotic variables on invertebrate size structure and diversity in coastal wetlands of Southeastern Spain
2016
Abstract Biomass and size-based estimations provide relevant information regarding ecosystem functioning and biotic interactions. Our aims were to study the effect of fish and macrophytes on the size structure of invertebrate assemblages (from rotifers to insects) in a set of coastal water bodies, estimating the biomass (total and main invertebrate groups), the biomass-size spectra (model of Pareto) and size diversity. In fishless ponds, cladoceran and ostracod biomass were higher, and they presented greater size diversity. In fish ponds, rotifer biomass presented greater proportion; while in fishless ponds, cladocerans were usually the most abundant taxa and the largest organisms. The biom…
Response of zooplankton to nutrient enrichment and fish in shallow lakes: a pan-European mesocosm experiment
2004
1. Responses of zooplankton to nutrient enrichment and fish predation were studied in 1998 and 1999 by carrying out parallel mesocosm experiments in six lakes across Europe. 2. Zooplankton community structure, biomass and responses to nutrient and fish manipulation showed geographical and year-to-year differences. Fish had a greater influence than nutrients in regulating zooplankton biomass and especially the relative abundances of different functional groups of zooplankton. When fish reduced the biomass of large crustaceans, there was a complementary increase in the biomasses of smaller crustacean species and rotifers. 3. High abundance of submerged macrophytes provided refuge for zooplank…
Seguimiento del fenómeno blanco de la laguna de la Cruz (Cuenca, España)
2020
[EN] In the present study, a five-year follow-up was performed by remote sensing of the calcium carbonate precipitation in La Gitana karstic lake also known as La Cruz (located on the province of Cuenca, Spain). The important role that calcium carbonate precipitation plays in the ecology of the lake is well known for its influence on the vertical migrations of phytoplankton, the concentration of bioavailable phosphorus and, therefore, the eutrophication and quality of the waters. Whiting take place between the months of July and August, and it can be studied at this time through its optical properties, with the main objective of offering updated data on a phenomenon traditionally studied an…