Impact of torrential rain on coastal ecosystem at kalpakkam, southeast coast of India

1609-1615The present study focuses on the drastic changes observed in the coastal ecosystem at Kalpakkam during flooding event due to huge rainfall that occurred in and around northern Tamil Nadu during December 2015. A significant increase in hydrological parameters (nitrate, phosphate, silicate, total nitrogen and phosphorous) was recorded as compared to previous years (2006-2014). In the present instance, the coastal water salinity which was about 19 psu was the lowest as compared to the data available since 1979. The phytoplankton population density was severely affected by the runoff. The present observed density 1.4 x 104 cells l-1 was the lowest among the available data at this coast. Availability of green algae species in the coastal waters was significantly high (10 species, 17 % of total species) as compared to previous reports. One of the most interesting features of this study was the observation of epibiosis on zooplankton in massive numbers. A comparison of previous occurrences of epibiotic relationship in plankton community with the present observation showed a staggering increase in epibiosis to 38 % of zooplankton species as compared to 5-13 % during 2008-2014

Dynamics in mesozooplankton assemblage with respect to environmental variables in the coastal waters of Kalpakkam, southwestern Bay of Bengal

1450-1464Heterogeneous assemblage of zooplankton community along coastal waters of Bay of Bengal comprised of 78 taxa of holo- and 15 mero-plankton. Major meroplankters observed were crustacean larvae, polychaete larvae, veliger larvae of bivalves, gastropod etc, echinoderm larvae and chordate larvae. Copepods dominated the zooplankton community with ~50 – 60% to the total composition of zooplankton, quantitatively. Qualitatively and quantitatively, zooplankton showed a strong positive correlation (p≥0.001) with chlorophyll-a and salinity respectively, indicating the role of phytoplankton and salinity for growth and survival of the former throughout the study period at this location. Copepod established a weak negative (p ≥ 0.01) and strong positive (p ≥ 0.001) correlation with temperature and salinity respectively. As copepod, their juveniles also were found dependent on salinity for their development by showing a strong positive correlation (p≥0.001) with the later. Zooplankton taxa showed seasonal specificity as the main regulator of food, either as grazers or as preys

Variations in community structure of phytoplankton in relation to physicochemical properties of coastal waters, southeast coast of India

223-241A comprehensive study on phytoplankton dynamics in the coastal waters of Kalpakkam showed a considerable increase (almost 3 fold) in phytoplankton species composition (185 species) as compared to the earlier findings (60 species). Despite such a massive change in floristic composition, 4-10 times reduction in total cell count was observed during the present study, which varied between 1.7 x 105 and 1.5 x 106 cells l-1. Another important feature of this study was the observation of Trichodesmium erythraeum bloom in the coastal waters. Concomitant with the bloom, a drastic fall in the number of phytoplankton species was noticed. The change in phytoplankton assemblages (density and species composition) during different seasons was significant and was found to be regulated by the change in water characteristics associated with monsoon. Diatoms dominated the phytoplankton assemblage followed by dinoflagellates. Asterionellopsis glacialis and Thalassionema nitzschioides were found to be dominant species among diatoms and dinoflagellates respectivaly, Prorocentrum micans and Protoperidinium sp. were the dominant forms. Salinity was found to be an important parameter influencing the species composition, standing stock and succession of phytoplankton at this location. Salinity apparently influenced the phytoplankton density positively. Nitrate was found to be the limiting factor for phytoplankton growth during late summer and pre-monsoon periods, whereas, the role of silicate and phosphate remained insignificant in this regard

First record of association of planktonic diatom <i>Chaetoceros coarctatus</i> Lauder, 1864 with a peritrich ciliate epibiont <i>Vorticella oceanica</i> Zacharias, 1906 (Ciliophora: Peritricha) from the Indian Ocean region

1806-1809Vorticella oceanica Zacharias, 19061, a peritrich ciliate was found on the marine planktonic diatom Chaetoceros coarctatus Lauder, 18642 from the coastal waters of southwestern Bay of Bengal. The present report can be considered as the first report of the epibiont Vorticella oceanica from the Indian coastal water as well as from Indian Ocean

Assessment of temporal variation in coastal water characteristics through multivariate statistics- A case study at southwestern Bay of Bengal, India

1718-1731A study was carried out in the coastal waters of Kalpakkam, southeast coast of India, in order to find out the prevalence of different water masses in a spatio-temporal scale. This region of southwestern Bay of Bengal is influenced by both southwest and northeast monsoon. However, in absence of any major perennial freshwater input into the coastal water, the water mass characteristics in this region mainly depends upon the coastal current pattern. Statistical analysis showed two temporally distinct water mass; one during the monsoon period and the other during the pre- & post-monsoon periods. Cluster analysis also depicted existence of a well marked spatial heterogeneity in the study area.  Five principal components developed showed distinct environmental states of coastal waters such as nitrogen enrichment, phytoplankton growth, phosphate enrichment, low dissolved oxygen & high temperature condition and nitrite enrichment which might have existed at this location on a temporal scale.

New record of a protozoan ciliate epibiont, <i>Acineta</i> <i>karamani</i> Hadži 1940 on copepod host <i>Labidocera</i> <i>acuta</i> from the Indian Ocean

1802-1805Acineta karamani Hadži 1940, an epizoic protozoan ciliate was found attached on the copepod Lbidocera acuta from the coastal waters of southwest Bay of Bengal. The present report forms the first record of the epibiont Acineta karamani from the Indian coast and the Indian Ocean

Studies on the settlement and succession of macrofouling organisms in the Kalpakkam coastal waters, southeast coast of India

747-761<span style="font-size:11.0pt;font-family: " times="" new="" roman","serif";mso-fareast-font-family:"times="" roman";mso-bidi-font-family:="" mangal;letter-spacing:.1pt;mso-ansi-language:en-gb;mso-fareast-language:en-us;="" mso-bidi-language:hi"="" lang="EN-GB">Study was carried out to evaluate the fouling pattern, dominant species and their seasonal succession in waters of east coast of India. Three series (weekly, monthly and cumulative) of teak wood panels were exposed to coastal waters.<span style="font-size:10.0pt;mso-bidi-font-size: 11.0pt;font-family:" times="" new="" roman","serif";mso-fareast-font-family:"times="" roman";="" mso-bidi-font-family:mangal;letter-spacing:.1pt;mso-ansi-language:en-gb;="" mso-fareast-language:en-us;mso-bidi-language:hi"="" lang="EN-GB"> There is wide variation in the colonization of the biofoulers on the weekly panels.&nbsp;&nbsp; The lowest and the highest numbers of organisms observed were between 1 and 136 per cm2, respectively. Dominance of barnacles (12.4-99%) on weekly panels was found throughout the year. Sizeable contribution (~7% of the total density) of oyster settlement was observed for the first time from this locality. Pattern of ecological succession observed was barnacles - hydroids - sea anemones - ascidians and finally green mussels. Weekly results, available for the first time for this locality, form the baseline data for future reference and impact assessment studies. Biofouling biomass (g. per 100 cm2) of weekly panels varied between 1 and 11, however, a steep increase in biomass was observed in cumulative panels. These biomass values compared well with earlier results. Total number of fouling taxa observed was only 30. A shift in the peak settlement period of green mussels, was observed as compared to the earlier report. Environmental parameters such as salinity, chlorophyll and phytoplankton density appeared to have significant (p≥ 0.01) contribution on biofouling settlement.</span

Changes in mesozooplankton community structure during Trichodesmium erythraeum bloom in the coastal waters of southwestern Bay of Bengal

1282-1293Present study addresses variability in mesozooplankton community structure (size ranges from 0.2-20 mm) during the appearance of diazotrophic marine cyanobacterium Trichodesmium erythraeum bloom in the coastal waters southeastern part of India. Zooplankton density (individuals per 10 m3) was the maximum during pre-bloom period (5.5 x 105) followed by bloom (4.9 x 105) and post-bloom period (4.3 x 105). Copepods contributed ~ 64 % of the zooplankton abundance during pre-bloom period in which calanoids were dominant (41%). Carnivore copepods (25%) (Cyclopoids and Poicilostomatoids) dominated over herbivore (23%) (Paracalanidae) during the peak bloom. Non-copepod holoplankters and meroplankters were dominant during pre-bloom period. The cladoceran, Evadne tergestina (35% of total non-copepod crustacean holoplankton) was found to be the most important species during bloom period. Among the meroplankters, cirripede nauplii (59% of the total meroplankton) were dominant form during bloom period. Co-occurrence of Trichodesmium bloom with high abundance of Penilia avirostris & Evadne tergestina and association of Acartia spinicauda and Oithona spp., in large numbers during bloom were the interesting features of this study