Sinking food supply : does composition, diversity, or quantity of food supply influence macroinfaunal communities?

Kelly, Michael C. (2009) Sinking food supply : does composition, diversity, or quantity of food supply influence macroinfaunal communities? Masters thesis, Memorial University of Newfoundland.

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Abstract

The role that food supply may play in determining patterns of biodiversity of shallow-water benthic macrofaunal communities is not well understood. This work tests the hypotheses that different types, diversity, and amount of phytodetrital material will attract different species and diversity of colonizing fauna. In situ experimental enrichment patches were created on the muddy seafloor at 20 m depth in a small cove in Bonne Bay, Newfoundland. Separate experiments tested the importance of different types and amounts of phytodetritus by gently syringing material onto otherwise undisturbed sediment. Push core samples were collected by divers 1 week and 5 weeks after enrichment and the experiments were repeated during the summer and the fall to test the importance of different seasons. Ambient fauna were also sampled with push cores at approximately two-week intervals through the summer and early fall. A strong seasonal signal was detected within the macrofaunal community with significant abundance increases during the study period, and there was also evidence of a strong recruitment event. Nonetheless, the composition of the phytodetrital food pulses tested had little effect on macrofaunal community diversity, structure and species composition at this site. Varying amounts of phytodetrital pulse showed reduced species diversity with increased enrichment, but this response was rapid and quickly disappeared, suggesting that food patches are rapidly utilized and short lived. The rapid utilization of phytodetrital patches may be characteristic of productive Newfoundland waters, and the absence of a specialized response to phytodetritus by Bonne Bay macrofaunal communities suggests they may be less food limited than many other benthic environments.

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