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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.

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Gelatinous zooplankton – a potential threat to the ecosystem of the Puck Bay (the southern Baltic Sea, Poland)

Olenycz M.

Biuletyn Instytutu Morskiego w Gdańsku

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2015

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Vol. 30, No. 1

78--85

EN

Gelatinous zooplankton is a group of organisms, which in recent decades has become one of the most important elements to shape the marine ecosystem. Their growing numbers and spreading to the new marine regions, in combination with the high feeding rate, causes significant changes in the flow of energy in the food webs. The only regularly-occurring gelatinous zooplankton species in the Puck Bay area is scyphozoan Aurelia aurita, most abundant in the summer and fall seasons. As shown in Barz and Hirche’s (2005), Möller’s (1980a), Schneider’s (1989), and Schneider and Behrends’ (1994) studies, the abundance of jellyfish in Bornholm Basin and Kiel Bight was several times lower than that in Puck Bay. Nevertheless, the authors of these studies concluded that the population of A. aurita can significantly reduce mesozooplankton and fish resources by preying on their larvae and eggs. Taking this into account, it is possible that the impact of A. aurita medusae on the Puck Bay ecosystem is even higher than in other parts of the Baltic Sea. Verification of this thesis requires detailed investigation; the scope of which should include investigation of: A. aurita food selectivity and long-term mesozooplankton, and A. aurita medusae abundance. The aim of this study, based on the few data in the literature, is to estimate if the gelatinous zooplankton is also an important element of the .

PL

Zooplankton galaretowaty to grupa organizmów, która w ostatnich dekadach stała się jednym z najważniejszych elementów kształtujących ekosystemy morskie. Ich rosnąca liczebność i rozprzestrzenianie się na nowe akweny w połączeniu z wysokim tempem żerowania, powodują istotne zmiany w przepływie energii w sieciach troficznych. Celem pracy była próba zbadania, na podstawie nielicznych danych literaturowych i własnych danych niepublikowanych, czy zooplankton galaretowaty jest również istotnym elementem ekosystemu Zatoki Puckiej. Jedynym regularnie występującym w tym akwenie gatunkiem z tej grupy zwierząt jest Aurelia aurita, która w miesiącach lata i jesieni występuje w wysokiej liczebności (Olenycz – dane niepublikowane). W przypadku Basenu Bornholmskiego i Zatoki Kilońskiej stwierdzono (Möller 1980a, Schneider 1989, Schneider and Behrends 1994, Barz and Hirche 2005), że liczebność meduz była około kilkukrotnie mniejsza niż w przypadku Zatoki Puckiej. Tym niemniej autorzy tych badań uznali, że populacja tego gatunku może znacząco redukować zasoby mezozooplanktonu i ryb, poprzez żerowanie na ich larwach i ikrze. Potencjalnie więc, wpływ meduz A. aurita Zatoki Puckiej jest większy niż w przypadku innych rejonów Bałtyku. Jednak aby potwierdzić tę tezę należy przeprowadzić kompleksowe badania, które swym zakresem objęłyby długoterminowe analizy wybiórczości pokarmowej meduz A. aurita oraz zmian liczebności mezozooplanktonu i meduz A. aurita.

3

Summer mesozooplankton community of Moller Bay (Novaya Zemlya Archipelago, Barents Sea)

Dvoretsky V. G., Dvoretsky A. G.

Oceanologia

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2013

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No. 55 (1)

205-218

EN

Novaya Zemlya Archipelago is the eastern boundary of the Barents Sea. The plankton of this region have been less intensively studied than those of other Arctic areas. This study of the mesozooplankton assemblage of Moller Bay was conducted in August 2010. The total mesozooplankton abundance and biomass ranged from 962 to 2980 individuals m-3 (mean š SD: 2263 š 921 indiv. m-3) and from 12.3 to 456.6 mg dry mass m-3 (mean š SD: 192 š 170 DM m-3) respectively. Copepods and appendicularians were the most numerous groups with Oithona similis, Pseudocalanusspp., Acartiaspp., Calanus glacialis and Oikopleura vanhoeffenni being the most abundant and frequent. Mesozooplankton abundance tended to decrease with depth, whereas an inverse pattern was observed for the total biomass. Total mesozooplankton biomass was negatively correlated with water temperature and positively correlated with salinity and chlorophyll a concentration. Comparison with previous data showed significant interannual variations in the total zooplankton stock in this region that may be due to differences in sampling seasons, climatic conditions and the distribution of potential food sources (phytoplankton and seabird colonies).

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Environmental study of the seasonal succession of mesozooplankton in a brackish water Odra River estuary during 2003–2005

Chojnacki J.C., Tyluś K.

Journal of Ecological Engineering

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2013

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Vol. 14, nr 2

12--25

EN

The entire estuary water is dominated by the discharge of the River Odra into the Szczecin Lagoon. The water body is brackish and the salinity in the central part ranges 0.5 and 2 PSU. The Lagoon has a long eutrophication history; usually, two phytoplankton biomass peaks are observed: Diatoms in spring and blue-green algae in summer. The recent data on zooplankton is limited. Rotifers and Cladocerans supply the bulk of the zooplankton biomass. The ichtiofauna is composed of fresh and brackish water, migratory and marine species. Zooplankton and water samples were collected during 2003–2005. The results suggest that during 10 season’s climate in Odra River estuary, Cladocera were the dominant group, large impact on the density of mesozooplankton were: Daphnia cucullata and Daphnia longispina, Copepoda played a lesser role in the Odra River estuary than Cladocera. Biomass of mesozooplankton from the Lagoon was significantly higher compared with the biomass of mesozooplankton from Odra River estuary, which could be related to a greater inflow of nutrients into the Lagoon and the increased growth of phytoplankton, which forms an excellent first stage food web for herbivorous and carnivorous zooplankton, and fish and consequently cormorants.

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Spatial and temporal variability of Copepoda in the pelagic zone of the Pomeranian Bay (2001-2003)

Chojnacki J.C., Machula S., Orłowski A.

Oceanological and Hydrobiological Studies

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2007

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Vol. 36, No.1

29-54

EN

This investigation of Pomeranian Bay waters was conducted from March 2001 to August of 2003 from aboard the r/v Nawigator XXI, which is owned by the Maritime Academy in Szczecin. A total of 147 water samples were collected at 15 stations on three transects in the Pomeranian Bay from Świnoujście, Międzyzdroje, and Dziwnów to the Odra Bank. Zooplankton was sampled with a Bongo type planktonometer O = 20 cm with a mesh size of 80 žm during 10 min. filtering hauls in the pelagic zone from the bottom to the surface at an average vessel speed of 3 - 4 knots. The method developed and published by Orłowski was used to transform the large amount of seasonal data for the entire study period into isoline illustrations of the spatial structures in the Pomeranian Bay of mesozooplankton and selected species, namely Acartia bifilosa, Acartia longiremis, Pseudocalanus elongatus, and Temora longicornis. The average mesozooplankton aggregations in ten consecutive seasons at the 15 stations investigated from 2001 to 2003 in the entire Odra estuary area fluctuated from 2,442 to 92,200 ind. m-3. The highest species variety was noted among marine Copepoda, which was the dominant group in virtually every season investigated. Their maximum abundance reached as much as 213,493 ind. m-3. The euryhaline species A. bifilosa occurred throughout the research period and at all stations at an abundance that reached 210,443 ind. m-3. The seasonal succession series were as follows: in spring, the dominants were Acartia spp. and Evadne nordmanni; in summer - Keratella cochlearis, Bosmina coregoni maritima, and A. bifilosa; in fall – T. longicornis and Acartia spp.; in winter – T. longicornis and Centropages hamatus.

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Factors describing the distribution of the zooplankton community in the Gulf of Finland in the context of interactions between native and introduced predatory cladocerans

Pollumäe A., Kotta J.

Oceanologia

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2007

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No. 49 (2)

277-290

EN

Mesozooplankton communities were studied monthly at six sites in the Gulf of Finland during six ice-free seasons. The abundances of different zooplankton taxa were related to temperature, salinity, eutrophication level (total nitrogen and phosphorus), phytoplankton Chl a and density of predatory cladocerans, including the non-indigenous Cercopagis pengoi and the native Leptodora kindtii. The results indicated that variability in the zooplankton communities was correlated not only with predation by mesozooplankton but also with bottom-up effects. Predation by the non-indigenous C. pengoi may significantly affect the dynamics of Cladocera and Rotatoria in the Gulf of Finland during the summer season.