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Impact of human-altered hydrographical setting on the Copepod community structure in an extensive tropical estuary along the southwest coast of India

Nagarathinam Arunpandi, Retnamma Jyothibabu, Loganathan Jagadeesan, Singaram Parthasarathi, Arayillath Anjusha, Jose Albin Konnakkamannil

Oceanologia

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2021

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No. 63 (1)

115--132

EN

This study presents how human-altered hydrographical settings (flow restrictions) impacts the natural distribution and community structure of copepods in the Kochi Backwaters (KBW), the largest monsoonal estuary along the southwest coast of India. This study is primarily based on an extensive seasonal sampling in the KBW and their comparison with a historical data set. Thannermukkom Barrage (TB) was built in the southern section of the KBW in the 1970s to prevent saline water intrusion to the upstream during the non-monsoon periods. Thirteen locations (1-4 in the downstream, 5-9 in the midstream, and 10-13 in the upstream) were sampled in this study over the entire stretch of the KBW during the Pre-Southwest Monsoon (PRM), Southwest Monsoon (SWM), and Post-Southwest Monsoon (PSWM). The overall effect of TB in the KBW is a seaward push of mesohaline conditions during all seasons with varying intensities. In response to the seaward push of mesohaline conditions, copepods Acartiella keralensis, Acartia plumosa, Acartia sp., Pseudodiaptomus annandalei, Pseudodiaptomus serricaudatus, Euterpina acutifrons and Oithona brevicornis showed a corresponding spatial shift for their highest abundance and diversity from midstream during PRM to the downstream during the SWM/PSWM. Multivariate and IndVal analysis demarcated many indicator species of copepods of different hydrographical settings in the KBW. A comparison with the historical data set showed that there is an apparent long-term change in hydrography, copepod composition and community structure in the upstream of the KBW due to TB.

2

Short-term variation of zooplankton community in Cintra Bay (Northwest Africa)

Berraho Amina, Abdelouahab Hinde, Baibai Tarik, Charib Said, Larissi Jamila, Agouzouk Aziz, Makaoui Ahmed

Oceanologia

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2019

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No. 61 (3)

368--383

EN

This is the first study that describes the spatial-temporal distributions of the zooplank- ton community and potential control factors in Cintra Bay. Zooplankton were sampled using a bongo net, 150 μm mesh size, during two surveys, in autumn 2015 and spring 2016, extending from the coast to the open sea. Fourteen zooplankton groups were identified, where copepods represented 49.1% and 92.5% of the total abundance in autumn 2015 and spring 2016, respectively. Tintinnids accounted for 39.7% and 4.7%, respectively. The total zooplankton abundance was higher in autumn (55 992 ind m-3) than in spring (2123 ind m-3). Nineteen species of copepods, belonging to 14 families, were identified. Euterpina acutifrons and Oithona nana were the most common and abundant species. The Acartiids were represented by three species (Acartia clausi, A. tonsa and A. bifilosa) in autumn and one species in spring (A. clausi). The copepods diversity was significantly different between the two seasons showing high values at the entrance and the center of the bay in autumn 2015 and in the southern half of the bay in spring 2016. The copepod structure was characterized by 13 species at different degrees of contribution in autumn 2015. In spring 2016, only four species qualified as indicator species although their contribution was not significant. Given its large opening on the ocean, Cintra Bay benefits largely from the conditions of the oceanic environment, particularly the upwelling. This situation is likely to have an impact on the spatiotemporal variability of the composition and distribution of zooplankton, especially the copepods.

3

Grazing of the copepod Cyclops vicinus on toxic Microcystis aeruginosa : potential for controlling cyanobacterial blooms and transfer of toxins

Mohamed Z. A., Bakr A. A., Ghramh H. A.

Oceanological and Hydrobiological Studies

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2018

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Vol. 47, No. 3

296--302

EN

Grazing of zooplankton on phytoplankton may contribute to a reduction of harmful cyanobacteria in eutrophic waters. However, the feeding capacity and interaction between zooplankton and toxic cyanobacteria vary among grazer species. In this study, laboratory feeding experiments were designed to measure the grazing rate of the copepod Cyclops vicinus on Microcystis aeruginosa and the potential microcystin (MC) accumulation in the grazer. Copepods were fed a mixed diet of the edible green alga Ankistrodesmus falcatus and toxic M. aeruginosa for 10 days. The results showed that C. vicinus efficiently ingested toxic Microcystis cells with high grazing rates, varying during the feeding period (68.9–606.3 Microcystis cells animal-1 d-1) along with Microcystis cell density. Microcystis cells exhibited a remarkable induction in MC production under grazing conditions with concentrations 1.67–12.5 times higher than those in control cultures. Furthermore, C. vicinus was found to accumulate MCs in its body with concentrations increasing during the experiment (0.05–3.21 μg MC animal-1). Further in situ studies are needed to investigate the ability of Cyclops and other copepods to assimilate and detoxify MCs at environmentally relevant concentrations before deciding on the biocontrol of Microcystis blooms by copepods.

4

Vertical distribution of zooplankton in the epipelagic zone off Sharm El-Sheikh, Red Sea, Egypt

Dorgham M.M., Elsherbiny M. M., Hanafi M. H.

Oceanologia

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2012

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No. 54 (3)

473-489

EN

The purpose of the present study was to track the seasonal vertical distribution of zooplankton abundance in the epipelagic zone off Sharm El-Sheikh, Red Sea. Zooplankton samples were collected seasonally within the depth ranges of 0-25, 25-50, 50-75, 75-100 m at a single station off Sharm El-Sheikh City. The present study is a trial to expand knowledge about the structure as well as the vertical distribution of the epipelagic zooplankton community in the Gulf of Aqaba in general and in its southern part in particular. The results indicate the occurrence of 52 copepod species and several species of other planktonic groups in the study area; the zooplankton standing crop fluctuated between 1124 and 4952 organisms m-3. Copepods appeared to be the predominant component, forming an average of 86.5% of the total zooplankton count, and with other groups demonstrated a markedly different seasonal vertical distribution. Twelve bathypelagic copepod species were reported during the present study, and five species were new to the area, having migrated northwards from the main basin of the Red Sea.

5

Salinity level and occurrence of centropagid copepods (Crustacea, Copepoda, Calanoida) in shallow lakes in Andes Mountains and Patagonian Plains, Chile

De Los Rios P., Contreras P.

Polish Journal of Ecology

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2005

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Vol. 53, nr 3

445-450

EN

In Andes Mountains (14-27°S) and Patagonian plains (45-53°S) in Chile, there are numerous shallow saline and sub-saline lakes. These water bodies have important temporal and spatial variation of their salinity caused by mineral composition of their watershed or exposition to arid weather. In this study we compared the salinity level and the occurrence of centropagid copepods (Crustacea, Copepoda, Calanoida) in water bodies of both regions. In the Andes Mts the calanoids inhabit water bodies of salinity lower than 90 g l-1, and the representative species was Boeckella poopoensis (Marsh 1906), that occurs between 5.0 to 90.0 g l-1. In Patagonian plains, the copepods occur at salinity level between 0.1 to 16.0 g l-1, and within these values most frequent are B. popei (Mrázek 1901) and Parabroteas sarsi (Mrázek 1901). Both species can coexist with other calanoid species.