Testing for nematode–granulometry relationships

The majority of studies have advocated that diversity of marine nematodes increases with increasing sediment grain size, although the opposite trend has also been suggested. The controversy is partially caused by not taking into account the effect of density on patterns of diversity and by analyzing datasets from different environments. The present study investigated nematode assemblages from sediments varying from very fine sand (mean grain size of 0.12 mm) to very coarse sand (1 mm) in shallow sublittoral marine environments. Contrary to previous studies, species richness was constant along the granulometric spectrum, despite significant changes in composition. The dominant genera were separated into five groups according to their optimum distribution and there was little overlap between these groups. Concepts from the niche theory explain to some extent the observed patterns. For instance, some of the coexisting genera were from different feeding types

State of the art of the meiofauna of Brazilian Sandy Beaches

Abstract In Brazil, meiofauna studies began in the middle of last century, but they adopted a purely taxonomical approach, describing species from various zoological groups. After this first step, this benthic group was largely neglected until the end of the 20th century when ecological studies began. We here provide a brief review of present knowledge of the meiofauna found on Brazilian sandy beaches to provide information for ReBentos (Coastal Benthic Habitats Monitoring Network). Our methodology consisted of a bibliographic survey undertaken using different datasets (Web of ScienceTM, SCOPUS, Google Scholar and Lattes Plataform). For the survey, we considered only those studies published till early 2015. Our analysis showed that the number of meiofauna studies has increased over the last two decades, though they are mainly still concentrated on the Southeast of Brazil. These studies aim to explain the distribution pattern of the meiofauna of the intertidal region of sandy beaches. Based on the results, we presented a discussion of three main topics, i.e., (a) current knowledge of Brazilian sandy beach meiofauna, (b) sampling strategies for monitoring of the meiofauna, and (c) use of the meiofauna as a tool to assess climate change. We trust that this brief review will be useful as a starting point for the delineation of further climate change investigations into sandy beach meiofauna

Nematodes as indicators of shrimp farm impact on an amazonian estuary (Curuçá, Pará, Brazil)

Abstract Shrimp farming reduces demand on wild fishery stocks and avoids environmental damage resulting from fishing practices, however, it has the potential to affect the water quality if not properly managed. In this study the impacts of a shrimp farm in an Amazonian estuary were evaluated, focusing on changes in nematodes regarding taxonomic composition, richness, density and diversity. Sampling was conducted in August 2004 (dry season) and January 2005 (rainy season) in the river at stations situated upstream and downstream at different distances from the main source of farm effluent discharge. Thirty-eight genera were recorded with Terschellingia dominating in the dry season and Terschellingia, Daptonema, Ptycholaimellus and Gomphionema in the rainy season. Abundances were within the range recorded in other estuaries and together with genera richness and diversity showed a strong temporal pattern with significantly higher values in the rainy season. No clear patterns of changes were observed at the stations. Some signs of organic enrichment were detected but they were not yet intense, probably a consequence of the strong local hydrodynamics and the age of the shrimp farm, which was just starting its operation. We recommend that in future studies on farming impacts a combination of factors, beyond the physical and chemical parameters of the water and sediments or taxonomic refinement, should be taken into account - such as the duration of the operation of the farm, the area occupied by ponds and the farm's production. Furthermore, we also believe that nematodes are a useful tool for evaluating aquaculture impacts due to the ease of sampling and because they are organisms at the base of marine food chain