Effect of Environmental Factors on Intertidal Nematoda in a Tropical Sandy Beach (Tamandaré Bay, Pernambuco, Brazil)

摘要

The present study describes spatial and temporal variation patterns of nematode assemblages in a tropical sandy beach (Tamandaré, in the state of Pernambuco, Brazil) and associates them with environmental factors (granulometry, chlorophyll-a, phaeopigments, organic matter, temperature, salinity, monthly rainfall, and wind velocity), testing the main hypothesis that these assemblages are influenced by seasonal variations even in areas where seasons of the year are not distinct. The Nematoda assemblage varied significantly across seasons (spring, summer, autumn, and winter) and between sampling stations (upper intertidal and lower intertidal) and sediment layers (0–10 and 10–20 cm). These differences were associated mainly with the variations of Calomicrolaimus formosus, dominant species of the nematode assemblage composed mainly of epistrate feeders. Diversity and evenness did not vary significantly in any situation, and richness was significantly higher in the lower intertidal area. None of the environmental factors were identified as the main structuring agent of the nematode assemblage, suggesting seasonality (or a group of factors that have seasonal variations, mainly rainfall) as the major influence. A sampling scheme considering four seasons for future temporal studies is recommended, including studies in tropical regions.