Rotifers in saltwater environments, re-evaluation of an inconspicuous taxon

Abstract

Rotifers are microscopic aquatic animals that comprise more than 1800 species. Most rotifer species live in freshwater and limno-terrestrial habitats, while thalassic environments (brackish+seawater) are thought to host few species. No recent review of saline rotifers is available. Here we report the results of a review of the literature concerning rotifers from saline environments, distinguished into three categories: stenohaline, euryhaline, and haloxenous, and found both in truly marine habitats and/or in inland saline waters. A total of about 200 studies, mentioning fully identified rotifers from saline waters, allowed us to list as many as 443 rotifer taxa at either specific, subspecific and infrasubspecific rank, corresponding to 391 nominal species. Truly thalassic taxa, not found in inland saline waters only, accounted for 289, including the ‘stenohaline’ (143) and the euryhaline (146) ones. As for freshwaters, the majority of the thalassic rotifers inhabit the psammon, or display a benthic–periphytic way of life, while the plankton likewise is less species rich and less abundant. The geographical distribution of the brackish and marine rotifers largely reflects the distribution of rotifer investigators, therefore, no biogeographical analysis can be performed yet. In conclusion, the analysis of literature citing rotifers in salt waters, uncovers an unexpected rotifer fauna: the apparent richness of the group in thalassic environments is worthy of being addressed by further investigations, as many species have been reported only by their description, suggesting either considerable endemism or taxonomic errors.

Zooplankton richness, abundance and biomass of two hypertrophic shallow lakes with different salinity in central Argentina

“…The species that prevailed in Bajo de Giuliani were the halotolerants Cletocamptus deitersi, M. mendocinus and B. poopoensis (Menu-Marque & Locascio de Mitrovich 1998, Echaniz et al 2006, Vignatti et al 2007). The highest number of shared species was recorded among rotifers and most of the taxa recorded were of cosmopolitan distribution (Segers & De Smet 2008) and euryhaline (Fontaneto et al 2006). The presence of large-sized cladocerans, especially that of the genus Daphnia, was sporadic and never reached high densities, possibly due to the predation exerted by fish (Grosman & Sanzano 2003, Boveri & Quirós 2007, Manca et al 2008) present in both lakes.…”

Seasonal variation and influence of turbidity and salinity on the zooplankton of a saline lake in central Argentina

“…The two rotifer species found have a wide distribution and are tolerant to salinity (Fontaneto et al, 2006).…”

A review of nickel toxicity to marine and estuarine tropical biota with particular reference to the South East Asian and Melanesian region

“…Provide high productivity, abundant detritus and high levels of organic carbon (Cavalcante et al 2009). Mangrove species diversity is believed to be highest in the Indo-West Pacific Very limited information on species diversity and relevance to SEAM, or marine systems in general, predominately freshwater organisms (Fontaneto et al 2006). Popular food source in aquaculture (Hagiwara et al 1995).…”