Benthic macrofaunal habitat use of the alga Caulerpa prolifera compared to the seagrass Halodule wrightii

Abstract

The abundance and species composition of the macrofauna inhabiting adjacent beds of the seagrass Halodule wrightii and the attached macroalga Caulerpa prolifera were compared seasonally from eight sites sampled within the Indian River Lagoon, Florida during 1987–1988. At each site, sampling employed a benthic corer, an epifaunal sampler, a dipnet, and fish traps to examine utilization patterns of different components of the fauna. Abundance of animals in both habitats was both high and similar. Epifaunal invertebrate densities averaged over 16,000 m−2 from H. wrightii and over 20,300 m−2 from C. prolifera. Despite a few species-compositional differences, there was no consistent difference in either the abundance or number of species of the macrofauna of C. prolifera versus H. wrightii for any sampling method except fish traps. Fish were significantly more abundant, but not more species rich, in H. wrightii. We conclude that C. prolifera offers habitat for many small invertebrates comparable to that of seagrass, making C. prolifera beds a valuable biological resource. While C. prolifera habitat may not support all the ecosystem services of seagrass beds and is not currently protected in Florida, it as a potential vegetated habitat refugium and may warrant management and protection practices similar to those for seagrass beds.