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

Abstract

The present study describes the nematode assemblage of the bay of Tamandaré (Brazil), a tropical sandy beach, during the low, flood, high and ebb tides of two consecutive tidal cycles in four different months of the year (May, July, September and November). The nematode assemblage was dominated by Metachromadora and Perepsilonema and varied significantly between months and tides. Densities were lower in July, and changes in assemblage structure occurred during the transitional periods between rainy and dry months, which showed the influence of rainfall. Flood and ebb tides appeared to exercise the greatest influences over the tidal cycle, although the patterns were not very clear. Identification at genera/species level is recommended for future studies, to better understand the patterns of nematode assemblages during tidal cycles. RESUMOO presente estudo descreve a associação de nematódeos da Baía de Tamandaré (Brasil), praia arenosa tropical típica, durante as marés (baixa, enchente, alta e vazante) de dois ciclos de maré consecutivos, em quatro meses diferentes do ano (Maio, Julho, Setembro e Novembro). A associação de nematódeos foi dominada por Metachromadora e Perepsilonema e variou significativamente entre meses e marés. Densidades foram mais baixas em julho e as mudanças na associação ocorreram durante meses de transição entre chuvoso e seco mostrando a influência do ciclo de chuvas. No ciclo de maré a enchente e vazante pareceram exercer a maior influência, embora os padrões não fossem muito claros. Recomenda-se que os estudos devam ser feitos ao nível de gêneros/espécies para melhor compreensão dos padrões das associações de nematódeos durante ciclos de marés.

Spatial and temporal variations of the subtidal meiobenthic community of the central coast of Venezuela

“…Although no correlations were made in this study with environmental variables, some studies indicate a trend to increase density during the dry season (Coull, 1970;Chindah & Braide, 2001). In the coastal area between Chirimena and Puerto Francés, an increase was observed in density during the rainy season and maximum temperatures, coinciding with what was found by Venekey et al (2014) in an intertidal zone in Brazil, Zaleha et al (2016) on Karah Island in China, and Baia & Venekey (2019) on sandy beaches in Brazil. This could be explained by the availability of food during the rainy season due to the enrichment of the marine environment by the discharge of nutrients from the adjacent rivers and streams.…”

State of the art of the meiofauna of Brazilian Sandy Beaches

“…Therefore, using short sampling intervals would provide a more reliable seasonal variability of the meiofauna. But perhaps There are also some studies that aim to assess the richness of copepods, tardigrades and nematodes for this geographical area (WANDENESS et al, 1998;DA ROCHA et al, 2009;VENEKEY et al, 2014aVENEKEY et al, , 2014b. A higher richness of copepods is associated with the presence of sea grass on sandy beach sediments (WANDENESS et al, 1998), whereas a higher diversity of nematodes is associated with the beach level and it is found on a lower beach level (VENEKEY et al, 2014b).…”

Free-living Nematodes of Brazilian Oceanic Islands: Revealing the Richness in the most isolated marine habitats of Brazil

“…In Brazil, the situation is not different. Considering the volume of studies, only very recently and only few works have attempted to identify specimens to the species level [38,39,40] and none of them identified all recorded genera to the species level. The demand for considerable experience and well-equipped laboratories to allow for a correct identification to the species level [41] has rendered marine nematode taxonomy quite stagnant.…”