Horizontal and vertical distribution of meiofauna on sandy beaches of the North Sea (The Netherlands, Belgium, France)

Abstract

Horizontal and vertical distribution of meiofauna on sandy beaches of the North Sea (The Netherlands, Belgium, France) Abstract Sandy intertidal zones were analysed for the presence of meiofauna. The material was collected on six macro-tidal sandy beaches along the North Sea (The Netherlands, France, Belgium), in order to analyse the vertical and horizontal meiofaunal distribution patterns. Eleven higher meiofauna taxa (one represented by larval stage-Copepoda nauplii) were recorded. The maximum total meiofauna abundance was observed on the Dutch beach (4,295±911 ind. 10 cm À2 ) in the Westerschelde estuary, while the lowest values (361±128 ind. 10 cm À2 ) were recorded in France at the Audresselles beach. Meiofauna of the different localities consisted mainly of nematodes, harpacticoids and turbellarians. Nematodes numerically dominated all sampled stations, comprising more than 45% of the total meiofauna density. Meiofauna was mainly concentrated at the sand surface with about 70% present in the uppermost 5 cm. Meiofauna occurred across the entire intertidal zone. A clear zonation pattern in the distribution of meiofauna taxa across the beaches was observed. The present work suggests that designation of exposed sandy beaches as physically controlled (McLachlan 1988) does not explain their biological variability.

Vertical distribution of meiofauna on reflective sandy beaches

“…In this study, the highest meiofauna densities were observed in the 10 to 30 cm strata. This contrasts with previous reports, according to which the highest meiofauna densities were generally observed in the top 10 cm of sediment (MCLACHLAN, 1978;OLAFSSON;ELMGREN, 1997;DE JESUS-NAVARRETE;HERRERA-GOMEZ, 2002;KAPUSTA et al, 2002;KOTWICKI et al, 2005). High densities at the sediment surface are generally related to the existence of an anoxic layer (chemical gradient) that forms immediately below the top centimeters of sediment in dissipative beaches (KOTWICKI et al, 2005), ultradissipative beaches (MARIA et al, 2012) and tidal flats (VIEIRA;FONSECA, 2013).…”

“…This contrasts with previous reports, according to which the highest meiofauna densities were generally observed in the top 10 cm of sediment (MCLACHLAN, 1978;OLAFSSON;ELMGREN, 1997;DE JESUS-NAVARRETE;HERRERA-GOMEZ, 2002;KAPUSTA et al, 2002;KOTWICKI et al, 2005). High densities at the sediment surface are generally related to the existence of an anoxic layer (chemical gradient) that forms immediately below the top centimeters of sediment in dissipative beaches (KOTWICKI et al, 2005), ultradissipative beaches (MARIA et al, 2012) and tidal flats (VIEIRA;FONSECA, 2013). However, on reflective beaches, such as Estaleiro and Estaleirinho Beaches, the low densities in the 0-10 cm stratum resulted from the re-suspension of the top centimeters of sediment by the wave energy (MCLACHLAN, 1989;BROWN, 2006), which conditioned the meiofauna to live in intermediate strata.…”

“…The consequence of this assumption is the non-stratified distribution of meiofauna and Nematoda in reflective beach sediments. However, this assumption is frequently disregarded in studies on the distributions of sandy beach organisms GHESKIERE et al, 2005;GHESKIERE et al, 2006;KOTWICKI et al, 2005). Other abiotic variables, such as grain size, salinity, redox potential, organic matter, temperature, water content, and depth of the water table (REISE; AX, 1979;STEYAERT et al, 1999), as well as biological interactions, may also determine the stratification patterns in reflective beaches.…”

How do harpacticoid copepods colonize detrital seagrass leaves?

“…The lower compartment was inserted 10 cm deep into the sediment. This depth was chosen since vertical penetration of copepods happens in surficial layer (Danovaro and Fraschetti 2002;Kotwicki et al 2005;Giere 2009), rarely exceeding 5-10 cm depth and therefore contamination from the surrounding sediments is excluded. The bottom of the tube remained open.…”

Interrelationships of bacteria, meiofauna and macrofauna in a Mediterranean sedimentary beach (Maremma Park, NW Italy)

“…However, studies on the ecological importance of these three components are still scarce (Koop and Griffiths 1982;Novitsky and Macsween 1989;Sundbaeck et al 1996;Albertelli et al 1999;Jedrzejczak 2002;Fabiano et al 2004;Kotwicki et al 2005;Moreno et al 2005a,b). Moreover, datasets deriving from sampling activities simultaneously targeted at the afore-mentioned benthic components are very rare, especially for the Mediterranean Sea.…”