The relationship between sandy beach nematodes and environmental characteristics in two Brazilian sandy beaches (Guanabara Bay, Rio de Janeiro)

Abstract

We investigated if the differences in density and nematode communities of intertidal sediments from two Brazilian sheltered sandy beaches were related to environmental characteristics. The upper tide level (UTL) and the low tide level (LTL) of both beaches were surveyed in January (austral summer) and June 2001 (austral winter) during low-spring tides, by collecting samples of nematodes and sediments. Differences in density between beaches, tidal level and seasons, and nematode community structure were investigated. Sediments from both beaches were composed of medium to very coarse sand. The highest nematode densities were found at the UTL, and significant differences between beaches, tidal levels and months were found. A total of 54 genera were found and the genera composition on both sheltered beaches was similar to other exposed worldwide sandy beaches. The density and structure of the nematode community at both beaches clearly varied along the spatial and temporal scales. Gravel percentage was the most important variable explaining the spatial distribution of the nematodes, determining the four sub-communities; this suggests that the sediment characteristics influence the nematode community, rather than physical hydrodynamic forces. Temperature and salinity were suggested to be important variables affecting the temporal variation.

Checklist of free-living marine nematodes from intertidal sites along the central west coast of India

“…In the sandy beach sediment samples as part of this study, Oncholaimus and Viscosia were found to be dominant genera and the reason for their dominance could be attributed to their large size (Fleeger et al 2011) and feeding habit (omnivores/predators) (Wieser 1953). It has been shown in various studies that the family Oncholaimidae which includes genera such as Oncholaimus and Viscosia are usually dominant in sandy environments (e.g., Maria et al 2013;Steif et al 2013). Additionally, we found the family Oncholaimidae to be most species rich as part of this study.…”

Testing for nematode–granulometry relationships

“…Fine sediments are generally characterized by the families Desmodoridae and Linhomoeidae, while coarse sediments are dominated by the families Enchelidiidade, Xyalidae, Cyatholaimidae, and Chromadoridae (Wieser 1959;Heip et al 1985;Fonseca and Fehlauer-Ale 2012;Maria et al 2013;Moens et al 2013). Although distinct assemblages along the spectrum occur, we still do not know how these changes occur.…”

The Influence of Tidal and Rainfall Cycles on Intertidal Nematodes: A Case Study in a Tropical Sandy Beach

“…In tropical regions, studies have been performed in Australia (NICHOLAS; HODDA, 1999, NICHOLAS, 2001, HOURSTON et al, 2005, Ecuador (CALLES et al, 2005) and French Polynesia (GOURBAULT et al, 1995). Despite the extensive coastline of Brazil, and the high diversity of the group in sandy beaches (VENEKEY et al, 2010), only a few surveys in the country have studied nematodes at low taxonomic levels (BEZERRA et al, 1997;NETTO et al, 2007;MARIA et al, 2008;MARIA et al, 2013, VENEKEY et al, 2014MELO et al, 2013). Whether studied at phylum, or low taxonomic levels, temporal studies of marine nematodes usually employ a monthly or seasonal scale, and mostly compare periods with or without rain.…”