MEPS 356:51-61 (2008)  -  DOI: https://doi.org/10.3354/meps07256

ABSTRACT: While the ecological importance of vegetated marsh edge habitats for many estuarine-dependent nekton is well documented, less is known about nekton use of the non-vegetated, water edge adjacent to marsh habitats and how physical variation of these habitats affects habitat use. The effects of morphological variation of these edge habitats on nekton communities were studied in Barataria Bay, Louisiana, USA. Monthly seining in fall 2003 (September, October, November) and spring 2004 (March, April, May) was conducted at 75 marsh edge study sites <10 m from the water-vegetation interface. Morphological variation in edge habitats (i.e. elevation, slope, irregularity) was quantified concurrent with nekton sampling at each sample site. Nekton assemblages were analyzed seasonally as different community assemblages were present in fall and spring, although consistent patterns emerged. Temperature and salinity were the dominant factors influencing nekton assemblages. Edge habitats with shallower slopes and greater marsh inundation supported more organisms and more resident species; in contrast, edges with steeper slopes supported more diverse and species-rich assemblages, possibly providing greater niche availability due to larger water depth gradients and increased edge irregularity, particularly when the adjacent marsh is not flooded. Use of the gently sloped sites by organisms probably reflects increased access to the marsh when flooded, and may provide shallow water refuge for many smaller species. Non-vegetated marsh edge provides valuable habitat for species, and the physical variation that exists within this habitat helps support a high species diversity.

KEY WORDS: Non-vegetated marsh edge · Nekton · Nekton community · Louisiana · Edge habitat