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Annual cycle of phytoplankton community through the water kolumn : study applied to the implementation of bivalve offshore aquaculture in the southeastern Bay of Biscay

Muñiz Oihane, Revilla Marta, Rodríguez José Germán, Laza-Martínez Aitor, Fontán Almudena

Oceanologia

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2019

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No. 61 (1)

114--130

EN

This study describes, for the first time, the annual variability of phytoplankton community in different layers of the water column in open waters off the Basque coast (southeastern Bay of Biscay). Phytoplankton composition, abundance and biomass, together with size-fractionated chlorophyll a, nutrients, and optical and hydrographic conditions were measured in an experimental bivalve culture area from May 2014 to June 2015. Water kolumn conditions showed the typical dynamics previously described for temperate areas, characterised by winter homogeneity and summer stratification. Phytoplankton temporal variability was studied at depths of 3,17 and 33 m, and was found to be related to those processes. In particular, temperature and nutrients (mostly nitrate and silicate) were the environmental variables which significantly explained most of the variability of chlorophyll concentration, whereas river flow was the main driver of abundance variability. Total chlorophyll was generally low (0.6 μg L-1 on average). Of the 194 registered taxa, 47.4% belonged to dinoflagellates and 35.1% to diatoms. In addition, diatoms showed the highest biomass values, and haptophytes represented the greatest expericontribution to cell-abundance. This fact, despite the low chlorophyll values indicating low phytoplankton biomass, could favour mussel growth given the high fatty acid content reported for diatoms and haptophytes.

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Zooplankton structure in high latitude fjords with contrasting oceanography (Hornsund and Kongsfjorden, Spitsbergen)

Ormańczyk M. R., Głuchowska M., Olszewska A., Kwaśniewski S.

Oceanologia

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2017

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No. 59 (4)

508--524

EN

Zooplankton inhabiting the Hornsund and Kongsfjorden fjords on Spitsbergen (Svalbard) were investigated in summer 2013. The goal of the study was to determine how the zooplankton communities vary in environments functioning under different oceanographic regimes. Sampling was conducted with nets of different mesh size and selectivity (56 μm WP-2, 180 μm MultiNet, and 1000 μm Tucker Trawl), which permitted comparing a wide size spectrum of zooplankton components. Species composition did not differ substantially between the fjords, but the zooplankton in Hornsund was almost two times less numerous, and it had lower biomass per unit volume. The highest abundance at both sites was in the smallest zooplankton size fraction found only in samples taken with 56 μm mesh WP-2 net. These comprised as much as 71% and 58% of the total zooplankton abundance in Hornsund and Kongsfjorden, respectively. The communities in both fjords had comparable contributions of Arctic and boreo-Arctic species biomass in the year of the study. However, the comparison of zooplankton characteristics over several years showed changes in abundance and biogeographic structure that corresponded with variations in the physical environments of the fjords. The results of the study permit predicting the possible effects of the increasing influence of Atlantic waters on zooplankton communities inhabiting Arctic marine pelagic ecosystems.

3

The structure of psammic rotifer communities in two boreal lakes with different trophic conditions : Lake Võrtsjärv and Lake Saadjärv (Estonia)

Lokko K., Virro T.

Oceanological and Hydrobiological Studies

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2014

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Vol. 43, No. 1

49--55

EN

Psammon communities are still poorly studied worldwide. The aim of the present study was to establish the structure of psammic rotifer communities including their diversity and quantitative parameters. A total of 41 rotifer taxa were found in hydro-, hygro-, and euarenal zones of eutrophic Lake Võrtsjärv and mesotrophic Lake Saadjärv during the study carried out in Estonia in 2008, including 11 rotifer species new to Estonia. In L. Võrtsjärv, the predominant rotifer taxa were Bdelloidea and Lecane psammophila. L. psammophila dominated in July and August and bdelloids prevailed in the rest of the year. In L. Saadjärv, the most abundant taxa were Lepadella ovalis, Keratella hiemalis, and Cephalodella megalocephala. The psammic rotifer community of L. Saadjärv proved to be more diverse than that of L. Võrtsjärv. Microphagous rotifers were dominant in L. Võrtsjärv. Raptorial feeders dominated in L. Saadjärv in summer and autumn and were more abundant at sites with coarser sand and low plant density.

4

Analysis of changes in cyanobacterial and algal flora of selected water reservoirs in Wrocław between 1878 and 2010 (south-west Poland)

Richter D.

Oceanological and Hydrobiological Studies

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2013

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Vol. 42, No. 4

379--397

EN

The paper includes the results of research carried out between 2006-2010 in the city of Wrocław (Poland). The water reservoirs selected for the analysis had previously described phycoflora and these studies were excellent comparative material for the today’s condition of their algoflora. The aim of this research was to conduct detailed studies of the current taxonomic composition of phycoflora in the chosen water reservoirs and to trace the changes which have taken place over time. The research determined the degree of similarity between the different communities in terms of the occurrence of common species and also the changes in their quantity. The study revealed 535 species of cyanobacteria and algae belonging to five phylas. The comparison of the composition of phycoflora from the studied ecosystems from previous years with the current results provided a model study showing the direction and pace of changes in the composition of the flora of cyanobacteria and algae in a given time. The species composition of cyanobacteria and algae in each year is adequate to the trophy of the studied water bodies. The processes in transforming communities of cyanobacteria and algae have led to the stabilization of the current status of the reservoirs as eutrophic.

5

Changes in the structure of phytoplankton in the lowest part of the Cybina River and the Maltański Reservoir

Kozak A.

Oceanological and Hydrobiological Studies

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2010

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Vol. 39, No.1

85-94

EN

The floristic composition, abundance, and biomass of phytoplankton in the Cybina River and the Maltański Reservoir were examined from April to October 2005. The analysis of the phytoplankton in the samples revealed statistically significant differences in both composition and abundance. The maximum abundance (39.2 × 10^3 ind. cm^-3) and biomass (56.8 μg cm^-3) of phytoplankton was noted in July 2005 at the outlet from the Maltański Reservoir. The lowest phytoplankton density was most often noted at the site located at the inlet of the Cybina River into the Maltański Reservoir. The quantitative and qualitative compositions of the phytoplankton varied at different sites. The highest taxonomical similarity was noted among the samples collected in the reservoir and at the outflow from it.

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The effects of copper and zinc on biomass and taxonomic composition of algal periphyton communities from the River Gharasou, Western Iran

Atazadeh I., Kelly M., Sharifi M., Beardall J.

Oceanological and Hydrobiological Studies

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2009

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Vol. 38, No.3

3-14

EN

Indoor artificial streams were used to evaluate the short-term (24 day) influence of copper and zinc, individually and in combination, on the biomass and taxonomic composition of algal periphyton communities. The effects of Cu (50 μg 1^-1) and Zn (1 mg 1^-1) were assessed using measurements of biomass, ash-free dry mass (AFDM), chlorophyll-a concentration, taxonomic composition and biovolume. In artificial streams with Cu, Zn and Cu+Zn, there were significant (p < 0.05) reductions of chlorophyll-a concentrations, dry mass and AFDM, and also changes in the species diversity and relative abundances of periphyton species. In artificial streams containing both Cu and Zn the taxonomic composition shifted from a Cyanophyceaen dominated community to one consisting mainly of Chlorophyceae, whilst the relative contribution of Bacillariophyceae was not significantly altered.