Benthic microalgae community response to flooding in a tropical salt flat

Abstract

This research evaluated the effect of flooding on the microphytobenthos community structure in a microbial mat from a tropical salt flat. Field samples were collected during four consecutive days: on the first three days the salt flat was dry, on the fourth day it was flooded by rain. In order to evaluate the community maintained in flood conditions, samples from this area were collected and kept in the laboratory for 10 days with sea water. The results of total abundance of microphytobenthos varied from 4.2 × 10 8 to 2.9 × 10 9 organisms L -1 , total density increased one order of magnitude under the effect of water for both situations of precipitation in the salt flat and in experimental conditions, an increase due to the high abundance of Microcoleus spp. Shannon index (H') was higher during the desiccation period. Our data suggest that changes in the abundance of organisms were due to the effect of water. The dominance of the most abundant taxa remained the same under conditions of desiccation and influence of water, and there is probably a consortium of microorganisms in the microbial mat that helps to maintain these dominances.Keywords: microphytobenthos, cyanobacteria, Microcoleus spp., hypersaline environment. Resposta da comunidade de microalgas bentônicas à inundação em uma planície hipersalina tropical ResumoEsse trabalho avaliou os efeitos da inundação na estrutura da comunidade microfitobentônica de um tapete microbiano em uma planície hipersalina tropical. As amostragens foram realizadas no campo durante quatro dias consecutivos: nos três primeiros dias o local estava seco e no quarto dia foi inundando com chuva. Para avaliar a comunidade mantida em condições de inundação, foram coletadas amostras dessa região, sendo mantidas em laboratório por 10 dias com água do mar. Os resultados mostraram que a abundância total do microfitobentos variou de 4.2 × 10 8 a 2.9 × 10 9 organismos L -1 , a densidade aumentou em uma ordem de grandeza com a influência da água, tanto na planície hipersalina como nas condições experimentais, um aumento que foi devido às maiores abundâncias de Microcoleus spp. O índice de Shannon (H') foi mais elevado durante o período de dessecação. Nossos dados sugerem que as mudanças na abundância dos organismos foram devidas ao efeito da água, a dominância dos táxons mais abundantes permaneceu a mesma durante as condições de dessecação e inundação, e possivelmente existe um consórcio entre os microrganismos do tapete microbiano no qual eles ajudam a manter essa dominância.Palavras-chave: microfitobentos, cianobactérias, Microcoleus spp., ambientes hipersalinos.

Estructura comunitaria del microfitobentos de la zona costera central de Venezuela

“…In comparison with other studies, densities were obtained which were 100 times lower than those found in Venice Lagoon in Italy (Facca et al, 2002) and in a saline wetland dominated by cyanobacteria in Rio de Janeiro, Brazil (Masuda and Enrich-Prast, 2016). In the case of the Caribbean Sea, comparisons cannot be made with other studies, since the few that calculated density associated it with macroalgae or marine phanerogam biomass, as they provide heterogeneity of space for the settlement and colonization of Epiphytes, growing the probability of increased microalgae richness and abundance.…”

Environmental influences on the cyanobacterial mat formation in the mangrove ecosystems along the southwest coast of India

“…Similarly, continuously fluctuating salinity in the intertidal mangrove ecosystems might exhibit the migration of cyanobacteria with inundation with ebb tides. The community composition of cyanobacterial assemblages is influenced by the salinity (Masuda & Enrich-Prast, 2016). The prominence of heterocyte cyanobacteria are observed in less saline conditions, however, increased salt content favoured the growth of non-heterocyst genera (Srivastava et al, 2009).…”