P.G. Menon

Bio: P.G. Menon is an academic researcher. The author has contributed to research in topics: Zooplankton. The author has an hindex of 1, co-authored 1 publications receiving 20 citations.

Annual variations in zooplankton from a polluted coastal environment

Abstract: Seasonal changes in the composition and distribution of zooplankton from the coastal waters of Trivandrum were studied. The study indicated that the effluent discharged from a nearby titanium dioxide factory did not affect the zooplankton abundance. Copepods followed by cladocerans contributed to the bulk of zooplankton. Species composition of zooplankton and their ecology are discussed. Diversity of zooplankton was high in the postmonsoon months and also in April

Response of zooplankton to physical changes in the environment: coastal upwelling along the central west coast of India

Abstract: Zooplankton composition and abundance were studied in a coastal upwelling situation from the central west coast of India. Upwelling and associated high biomass was found confined to a narrow coastal span. Zooplankton composition was dominated by a few species of herbivores and carnivores and was generally distinct from non-upwelling and offshore waters. Zooplankton had higher aggregations in the shallow upper mixed layer compared to the stratum below. High variability in zooplankton abundance occurred over short periods. Diel patterns in distribution or migration of zooplankton in inshore waters were not detectable.

The response of microzooplankton (20-200 μm) to coastal upwelling and summer stratification in the southeastern Arabian Sea

Abstract: During the late summer monsoon (LSM), coastal upwelling and river runoff have increased the nutrient concentration in the inshore region of the southeastern Arabian Sea. This has resulted in elevated chlorophyll-a (av. 40±18 mg m−2), phytoplankton abundance (av. 474±116×106 ind. m−2) and primary production (av. 917±616 mg C m−2 d−1). Diatoms were the major component of the phytoplankton community (av. 60±8% of the total abundance) during this period, followed by dinoflagellates (18±12%). However, the inshore locations of 10°N and 13°N transects behaved differently, with an exceptional abundance of phytoflagellates (>1010 ind. m−2). The microzooplankton (MZP) community was comprised of heterotrophic dinoflagellates (av. 60%), ciliates (av. 30%) and copepod nauplii (av. 5%); these showed marked variation in abundance between stations. The highest abundance (av. 283×104 ind. m−2) was at the inshore location of 10°N transect, where phytoflagellates were abundant. Contrasting to the LSM, intense surface layer stratification and depletion of nitrate (with a nitracline at 60 m depth), observed in the southeastern Arabian Sea during the spring intermonsoon (SIM) period, caused low phytoplankton abundance (av. 141±86×106 ind. m−2), chlorophyll-a (av. 19±11 mg m−2) and primary production (av. 146±68 mg C m−2 d−1). High temperature (>29 °C) and nitrate-depleted surface waters favoured the proliferation of Trichodesmium erythraeum at most of the locations. Total abundance of MZP during the SIM was markedly low (av. 20×104±13×104 ind. m−2), as was the species richness and diversity (0.36±0.02 and 0.57±0.15, respectively) compared to the LSM (1.17±0.31 and 2.72±0.34, respectively). During the SIM, the MZP community that occurs in the southeastern Arabian Sea is important, since smaller individuals are widespread and form the majority of phytoplankton community. The present study points also to the fact that the MZP could play an important role, even in nutrient-enriched environment, if smaller phytoplankton are abundant.