Assessing within habitat variability in plant demography, faunal density, and secondary production in an eelgrass ( Zostera marina L.) bed

Abstract

This investigation addressed faunal relationships with habitat structure within a Zostera marina community targeting differences between seagrass bed edge and interior. Z. marina biomass was significantly higher from the interior portions of the bed compared to the edge, but shoot density did not vary. Additionally, leaf width and length were significantly greater in the interior of the bed, suggesting greater total leaf area. Densities of larger organisms (> 0.85 mm) were significantly greater in vegetated samples ( Z. marina edge and interior) compared to unvegetated, but an analysis of similarities demonstrated significant faunal community differences among each of the identified habitats. Densities of small organisms (0.25–0.85 mm), however, were significantly greater at Z. marina edge compared to unvegetated samples and Z. marina interior. Additionally, secondary production (μg AFDW day − 1 ) was estimated based on the size distribution of taxa and showed significantly greater production from samples gathered in Z. marina compared to unvegetated samples. The relative size distribution of taxa was assessed using regression analysis and results showed that the size distribution was similar for samples collected at edge and interior Z. marina, but these distributions differed significantly when compared to unvegetated samples. The results of this study suggest that although similarities exist between edge and interior portions of Z. marina beds, especially compared to unvegetated habitats, noteworthy differences in faunal density, species composition, size distribution, and secondary production exist between edge and interior Z. marina.