Species Diversity and Community Assemblage of Planktonic Rotifers from Vembanad Estuary-Kerala, India

Abstract

Among the zooplankton, Rotifera comprise an integral part of the food chain and are important link between nanoplankton and carnivorous zooplankton. The diversity of rotifers is indicative of the ecological factors of the water body as they respond more quickly to environmental changes and appear as sensitive indicators of changes of water quality. In this context, species diversity of planktonic rotifers and its community assemblage in Vembanad backwater (Ramsar site) has been carried out from March 2012 to February 2013 from ten selected stations on North and South of the Thanneermukkom barrage. Abiotic and biotic parameters were determined and correlated with rotifer abundance to gain information about the forces that assembles the rotifer community in this dynamic environment. Maximum abundance was observed during monsoon (av. 8934 individual . During the present study 26 species of the rotifers belonging to 10 families were observed, with maximum abundance of Brachionus sp. (60%). Predominant species were Brachionus rotundiformis (16.4%), B. calyciflorus (6.6%), B. urceolaris (5.5%), B. plicatilis (4.05%), Keratella tropica (3.2%) and Asplanchna sp. (2.2%). Most of the dominant species observed were eurytopic freshwater forms that became less abundant towards downstream (station 8, 9 and 10) with respect to the salinity gradient prevailing in the estuary. Highest Shannon diversity index (4.51) was observed in station 3 (Rani) and lowest (2.73) in station 10 (Aroor). Multivariate Bio-Env (BEST) analysis showed that temperature, conductivity, salinity and phosphate best determined the abundance and distribution of rotifers in the Vembanad estuary. As the trophic status and rotifer assemblages of an ecosystem are very much related, a comprehensive study on the species diversity and community assemblage of rotifers in Vembanad estuary can furnish a valuable integrative index for further ecological assessment and monitoring of estuarine ecosystems.

Periphytic rotifers: A comprehensive study on species composition, substrate specificity and habitat preference down a tropical riverine system

“…Rajagopal et al (2010) supports this finding from three different ponds of Tamilnadu and reported that DO showed a negative correlation with zooplankton abundance. A negative association of DO with rotifer density and diversity has also been reported by Cleetus et al (2015). Esparcia et al (1989) reported that for a short period some rotifers can tolerate anaerobic or near anaerobic conditions even though most rotifers require oxygen concentration above 1.5 mg/l.…”

“…Galkovskaja (1987) stated that, if other factors not limiting, rotifers can reproduce over a wide range of temperatures. Cleetus et al (2015) reported that rotifer density has a significant positive association with nitrate and phosphate and a combination of variables like phosphate, conductivity, salinity, and the temperature was best in determining the diversity and distribution of the rotifer population. All these environmental factors act collectively to determine species abundance and distribution of periphytic rotifers.…”

: Seasonal zooplankton dynamics and its relations with environmental factors in Dalcar Urban Lake (Córdoba, Argentina)

“…Este lago, si bien comparte algunas características con el lago Dalcar (reducida transparencia y presencia de peces), se diferencia por su mayor extensión y su salinidad más elevada. La composición taxonómica del zooplancton de Dalcar estuvo dominada por los rotíferos, organismos que constituyen un importante enlace entre el nanoplancton y el zooplancton carnívoro (Retina et al, 2015) y que son capaces de modificar la trama trófica microbiana (Fermani et al, 2013). El dominio de la riqueza de los rotíferos es un rasgo típico de lagos de elevado nivel trófico (Lodi et al, 2011;Sarma et al, 2016) como es Dalcar y es una situación similar a la encontrada en los lagos pampeanos mencionados más arriba, en la laguna de Chascomús (Diovisalvi et al, 2010) y en el eutrófico lago del parque General Belgrano, en el sur de la ciudad de Santa Fe (José de Paggi & Paggi, 1976).…”

“…En todos los casos mencionados, al igual que en el lago Dalcar, entre los rotíferos predominaron especies de los géneros Brachionus, Keratella y Lecane, cuyas especies son consideradas indicadoras de eutrofia (Ferdous & Muktadir, 2009;Perbiche-Neves et al, 2013;Sarma et al, 2016;Azma-Hanim & Anis-Amalina, 2016). Además de éstas, otras especies encontradas en Dalcar son indicadores de eutrofia elevada, tales como P. dolichoptera o Filinia longiseta (Čeirāns, 2007;García Chicote, 2015;Retina et al, 2015;Azma-Hanim & Anis-Amalina, 2016).…”