Int.J.Curr.Microbiol.App.Sci (2019) 8(7): 2034-2042 International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 8 Number 07 (2019) Journal homepage: http://www.ijcmas.com Original Research Article https://doi.org/10.20546/ijcmas.2019.807.244 Diversity of Zooplankton in Seagrass Ecosystem of Mandapam Coast in Gulf of Mannar S. Deepika1*, A. Srinivasan1, P. Padmavathy1 and P. Jawahar2 1Department of Aquatic Environment Management 2Department of Fisheries Biology and Resource Management, Fisheries College and Research Institute, Tamil Nadu Dr. J. Jayalalithaa Fisheries University, Thoothukudi – 628 008. Tamil Nadu, India *Corresponding author ABSTRACT K e yw or ds The present investigation was carried out to assess the distribution of zooplankton in seagrass ecosystem in comparison with that of the coastal waters without seagrasses in Seagrass ecosystem, Gulf of Mannar. Water and plankton samples were collected from the seagrass ecosystem Zooplankton, (Station 1) and the control station without seagrasses (station 2) from September 2016 to Physico chemical parameters, Species May 2017. The physico chemical parameters were analysed and the mean values of composition, surface water temperature, salinity, pH, dissolved oxygen, nitrite, nitrate, phosphate, Species diversity silicate, gross primary productivity and chlorophyll-a were 27.72⁰ C, 34.17 ppt, 7.99, 3.85 -1 -3 -1 -3 index ml.l , 0.25µM, 0.01 µM, 0.63 µM, 1.03 µM, 0.22 mg.C.m .h and 0.24 mg.m respectively. Totally, 59 species of zooplankton were recorded from each of the two Article Info stations with the maximum density of 667400 and 935300 nos.m-3 in station 1 and 2 respectively. The higher density of zooplankton was observed during the summer months. Accepted: 15 June 2019 The species richness and diversity indices showed the maximum values of 7.13 and 1.58 bits.ind-1 respectively in seagrass ecosystem which indicates that the diversity of plankton Available Online: 10 July 2019 is more in seagrass ecosystem as that of the coastal waters without seagrasses. Introduction variety of resources and habitats and the coastal ecosystems are the most productive Among the marine ecosystems, coastal areas ecosystems on earth. Planktons are one of the of the seas are more fertile and productive important component of any aquatic regions than the offshore regions of the sea. ecosystem as these organisms forms the base Worldwide approximately half of the of the food chain. The distribution and growth population live in coastal zones and about a of plankton depend on the availability of the billion people rely on the coastal environment inorganic nutrients and the physico chemical for fish as their main source of protein. characteristics of the coastal waters. Coastal environment is very dynamic with Zooplankton are small heterotrophic animals, much cyclic and random process owing to a plays a key role in the coastal as well as 2034 Int.J.Curr.Microbiol.App.Sci (2019) 8(7): 2034-2042 oceanic food web. They form the intermediate 9⁰ 15'55''N; long 79⁰ 12'23''E) in comparison link between phytoplankton and fishes of the with the reference site without seagrasses at higher trophic levels and are playing the Kundhukal (Station 2, lat 9⁰ 15'13''N; long important link in the transfer of energy from 79⁰ 13'8''E) (Fig. 1) which is situated 2 km primary producers to the organisms of the away from station 1. The surface water higher trophic levels. Zooplankton also sample and plankton samples were collected includes the early life history stages of once in a month from the two stations (1 and commercially important fin fishes 2) from September 2016 to May 2017 to (ichthyoplankton) and shell fishes. analyse the physico chemical parameters of Zooplankton are being used as indicators of the water and to assess the diversity and the overall health of the ecosystem, since they biomass of phytoplankton. The water samples responds quickly to aquatic environmental were collected early in the morning at 7.00 changes. Temperature, salinity, and food a.m. to 9.00 a.m. in both the stations. Surface supply are some of the important factors that water temperature was measured using are known to cause spatial changes in standard mercury filled centigrade zooplankton populations (Fernandes and thermometer with an accuracy of 0.1⁰ C in Ramaiah, 2009). the sample collection site itself. The surface water samples were collected in a pre-cleaned GoM located between Rameswaram and polypropylene bottle in all the stations and Kanyakumari has a chain of 21 Islands (area transported to the laboratory for further of each Island 0.95 to 130 ha.) along the 140 analysis. The physico chemical parameters km stretch between Tuticorin and viz., salinity, pH, dissolved oxygen, nutrients Rameswaram at 08°55'- 09°15'N lat. and (nitrite, nitrate, phosphate and silicate), 78°0'- 79°16'E long (Gopakumar et al., 2009). primary productivity and chlorophyll-a were The GoM is unique for its heterogenous analysed for all the water samples by biological resources and commonly known as following the standard procedure of the ‘Paradise of Marine Biologists', which is a Strickland and Parsons (1972). legally protected Marine Biosphere Reserve (Jyothibabu et al., 2013). They have fringing Plankton samples were collected from the and patchy coral reefs, seaweeds, seagrasses surface water by filtering 500 l of seawater and mangrove rising from shallow areas of using hand plankton net (bolting silk no.30). the sea shore. They are biologically diverse, The collected plankton samples were ecologically productive and economically preserved in plastic bottle with 5% formalin valuable ecosystems which import and export in the site itself for further analysis at the considerable amount of nutrients and organic laboratory. Plankton samples were analysed matter between the terrestrial and marine for their species composition and plankton ecosystems. Presence of multiple habitats like density using Nikon Inverted Microscope seagrass beds, coral reefs and mangroves not (Eclipse TS 100). Zooplankton was identified only supports a rich variety of fauna but also using the keys of the standard publications of provides natural protection from storms and Kasturirangan (1963) and Santhanam and waves. Srinivasan (1994). For the quantitative estimation of phytoplankton, from the Materials and Methods plankton concentrate 1ml of sub sample was taken in a Sedgewick-Rafter counting cell The present investigation was carried out to which was subsequently placed in microscope study the zooplankton diversity in seagrass provided with a stage for counting. The ecosystem at Chinnapaalam (Station 1, lat density of zooplankton was expressed as 2035 Int.J.Curr.Microbiol.App.Sci (2019) 8(7): 2034-2042 numbers per m3. For each sample, two chordates (1.69% and 1 number), decapods counting were made and the average was (1.69% and 1 number), molluscs (1.69% and recorded. The species richness (D) of 1 number) and meroplanktonic forms plankton samples was determined following (32.20% and 19 numbers). The number of Gleason (1922) and species diversity was species distributed during different months calculated as per Shannon and Wiener (1949). was ranged from 19 to 36, while the minimum numbers was during the month of October Results and Discussion 2016 and the maximum numbers during April 2017. Copepods were recorded as the Physico chemical parameters dominant zooplankton species from the present study. The results of physico chemical parameters such as surface water temperature, salinity, Among the zooplankton species recorded, the pH, dissolved oxygen, nutrients (nitrite, species such as Favella phillippinensis, nitrate, phosphate and silicate), gross primary Acrocalanus gracilis, Paracalanus parvus, productivity and chlorophyll-a of station 1 Corycaeus danae, Oithona brevicornis, and 2 were depicted in Table 1 and 2. Euterpina acutifrons, Longipedia weberi, Sagitta sp., Bivalve veliger, Gastropod Zooplankton veliger, copepod nauplius and Lucifer zoea were found to be distributed commonly In the present investigation, a total of 65 during all months in both the stations. species of zooplankton were recorded from the two stations. At station 1, a total of 59 The overall zooplankton density at station 1 species of zooplankton were found to be ranged between 126900 and 667400 nos. m-3 distributed. The percentage composition and (Figure 2). The minimum and maximum number of species were tintinnids (11.87% densities were during the months of and 7 numbers), foraminifers (1.69% and 1 September 2016 and May 2017 respectively. number), copepods (47.46% and 28 numbers), The maximum density during May 2017 was cladocerans (3.39% and 2 numbers), contributed mainly by crustacean nauplius chaetognaths (1.69% and 1 number), (33.10%) followed by copepod nauplius chordates (1.69% and 1 number), decapods (21.13%), Oithona brevicornis (19.01%) and (1.69% and 1 number), molluscs (1.69% and Acrocalanus gracilis (8.45%). In station 2, the 1 number) and meroplanktonic forms overall density of zooplankton ranged from (28.83% and 17 numbers). The number of 89300 to 935300 nos. m-3 (Figure 2). The species distributed during different months minimum and maximum densities were was ranged from 18 to 40, while the minimum occurred during the months of October 2016 numbers was during the month of September and May 2017 respectively. 2016 and the maximum numbers during April 2017. At station 2, a total of 59 species of The maximum density during May 2017 was zooplankton were recorded. The percentage contributed mainly by copepod nauplius composition and number of species were (21.11%) followed by crustacean nauplius tintinnids (8.47% and 5 numbers), (14.07%), gastropod veliger (9.05%), Oithona foraminifers (5.08% and 3 numbers), brevicornis (8.54%), Acrocalanus gracilis copepods (44.07% and 26 numbers), (6.53%), Acartia erythreae (6.03%) and cladocerans (3.39% and 2 numbers), Euterpina acutifrons (6.03%).