Meiofaunal colonization of artificial substrates in an estuarine embayment

Artificial substrates were used to investigate the cryptic meiofauna of a Louisiana estuary. Three types of collectors were used as artificial habitats in colonization studies. Mesh collectors (composed of a plastic thread, approximately 74 m long, woven into a pad) and bottle brushes (with approximately 4400 plastic bristles per brush, each 2.5 mm long) were colonized equally well by meiofauna; Hester-Dendy plates with less structural complexity were colonized at a slower rate, especially by copepods. Nematodes and harpacticoid copepods were always the two most abundant meiofaunal taxa collected. Mesh collectors were retrieved in July and December after a 2-week colonization period to examine seasonal trends. Starting in December, a longterm colonization study was also performed to determine if an equilibrium abundance could be achieved; artificial substrates were collected after 2, 4 and 8 weeks. Meiofauna achieved high abundances (means ranged from 1000-20,000 individuals per collector) on artificial substrates regardless of season, and abundance was related to supply, water flow and capture efficiency of the substrates as well as behavior of the meiofauna. Copepod species diversity was low (6 species were observed in July and Ii in December). Diversity and evenness were significantly different between July and December, and among the three collections in the long-term study. The copepod species assemblage qualitatively differed between July and December. Our data suggest that an abundant and dynamic but understudied meiofaunal assemblage is present in this estuarine embayment. This assemblage is not associated with macroalgae but rather related to presence of hard substrates and seasonally abundant filamentous microalgae.