copepod community
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2022 ◽  
Author(s):  
Sourav Paul ◽  
Samya Karan ◽  
Bhaskar Deb Bhattacharya

Abstract Tropical cyclones are increasingly affecting the estuarine communities. Impacts of category-5 tropical cyclone Amphan (landfall on 20 May 2020 near Ganges estuary mouth) on the copepod community of Muriganga section of Ganges estuary was studied by sampling the copepod assemblages before (February to December 2019), shortly after (31 May to 12 June 2020) and post (September to November 2020) cyclone. Hypothesis was shortly after Amphan a relatively homogenous community consists of a few estuarine specialist copepods would succeed but within months that community would be replaced by a heterogenous one but those estuarine specialists would continue their dominance. Shortly after Amphan, species richness declined but the recovery process completed within months led by herbivorous Paracalanus parvus, omnivorous Bestiolina similis, Acartia spinicauda, Acartiella tortaniformis, and carnivorous Oithona brevicornis. Spatial homogeneity of the community that prevailed in Muriganga in pre-Amphan and shorty after Amphan was lost in post-Amphan. Community composition changed from pre- to shortly after to post-Amphan. Unilateral dominance of B. similis observed in pre-Amphan was challenged by P. parvus, A. spinicauda, A. tortaniformis and O. brevicornis shortly after Amphan and in post-Amphan. Acartia spinicauda proliferated shortly after Amphan and co-dominated the estuary along with A. tortaniformis but the latter replaced the former in post-Amphan. Copepods did rebuild their community within a few months from Amphan but experienced rearrangements of species composition, abundance, dominance hierarchy and feeding guilds, which may strain benthic-pelagic linkages of Ganges estuary so shall be monitored regularly by coastal institutions following uniform methods and best practises.


2021 ◽  
Author(s):  
Papiya Bhattacharya ◽  
Samya Karan ◽  
Bhaskar Deb Bhattacharya ◽  
Sourav Paul

Abstract Copepods are considered as indicators of ecological stresses of estuaries. Spatial-temporal changes of diversity, abundance, and dominance of the copepod community of India's Ganges River estuary were hypothesised to result from abiotic fluctuations, seasonal change and the COVID-19 lockdown which possibly affected the habitat. This hypothesis was studied by sampling the estuary on different occasions between February 2019 and October 2020. Salinity and pH showed significant temporal variability but not significant spatial variability. Water temperature showed no significant spatial-temporal variability. Salinity showed significant negative relationships with diversity and abundance of the copepod community. After the COVID-19 lockdown (between unlock phase 1 to 5), nutrient status of the estuary did not show significant temporal variation. The copepod community mostly comprised calanoids except for the cyclopoids Oithona spp. Relative abundances of Pseudodiaptomus binghami, Eucalanus crassus and Labidocera euchaeta declined but Paracalanus indicus, Acrocalanus gibber, Acrocalanus gracilis, Acartia spinicauda, Acartia sewelli and Oithona brevicornis increased after COVID-19 lockdown. Bestiolina similis was the most abundant copepod and along with Acartiella tortaniformis, Acartia spinicauda, Paracalanus parvus and O. brevicornis co-dominated the community on various occasions. Spatial ordination of the copepod community was not significant either in the pre- or post-lockdown period. Diversity and total abundance of the copepod community were affected neither by seasonal change nor by temporal variability of water temperature and pH. Temporal variability of species richness was significant only in the post-lockdown period. Pre- vs. post-lockdown comparisons of diversity indices and total abundance of the copepod community were not significant. Overall, copepods were not much affected by abiotic and seasonal changes, and the COVID-19 lockdown. That indicates their flexibility to habitat variability and less suitability as indicators of chronic ecological stresses of excessively large river-estuaries.


Author(s):  
Laura Rodrigues da Conceição ◽  
Lilian Elisa Demoner ◽  
Juliano Bicalho Pereira ◽  
Fernanda Perassoli ◽  
Renato David Ghisolfi ◽  
...  

Oceanologia ◽  
2020 ◽  
Author(s):  
Arunpandi Nagarathinam ◽  
Jyothibabu Retnamma ◽  
Jagadeesan Loganathan ◽  
Parthasarathi Singaram ◽  
Anjusha Arayillath ◽  
...  

2020 ◽  
Vol 8 (8) ◽  
pp. 567
Author(s):  
Marijana Hure ◽  
Mirna Batistić ◽  
Vedrana Kovačević ◽  
Manuel Bensi ◽  
Rade Garić

Copepod communities were studied along an east-west transect in the oligotrophic Southern Adriatic Sea. This dynamic region is under the influence of various physical forces, including winter vertical convection, lateral exchanges between coastal and open sea waters, and ingression of water masses of different properties all of which occurred during the investigation periods. Depth-stratified samples were taken with a Nansen net (250 µm mesh size) in pre- and post-winter conditions in 2015/2016. In December, the coastal copepod community was limited over the western flank, while epipelagic waters of the open and eastern waters were characterized by high diversity, low abundances in the central area, and subsurface/upper mesopelagic copepod species. In April, higher abundances were recorded over the entire vertical profile with the surface coastal copepod community present through the entire transect. Higher abundances in the central area during the post-winter period are probably a consequence of late-winter/early spring blooms near the center of the Southern Adriatic. Mesopelagic fauna of both months was characterized by high abundances of Haloptilus longicornis, characteristic species of the eastern Mediterranean, whose larger presence was favored by the cyclonic phase of the North Ionian Gyre and a consequent strong Levantine Intermediate Water ingression.


Polar Science ◽  
2020 ◽  
Vol 24 ◽  
pp. 100509
Author(s):  
Koki Tokuhiro ◽  
Yoshiyuki Abe ◽  
Jonaotaro Onodera ◽  
Makoto Sampei ◽  
Amane Fujiwara ◽  
...  

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