Layman, C. A. University of Virginia, cal8e@virginia.edu
Herod, J. A. University of Virginia, jamhe@aol.com
Smith, D. E. University of Virginia, des3e@virginia.edu

 
THE RELATIVE IMPORTANCE OF ABIOTIC AND BIOTIC FACTORS IN STRUCTURING MARSH POND COMMUNITIES: A SEASONAL CYCLE DETERMINING OBSERVED FISH ASSEMBLAGES
 
A series of experiments demonstrated that the fish community structure in marsh ponds is based on a predictable seasonal cycle of abiotic and biotic factors. The study was carried out in eight semi-isolated marsh ponds on a Virginia barrier island. Surf-zone fish, potential colonizers of the ponds during periodic washover events, were subjected to different levels of intra- and inter-specific competition using in situ enclosures. During summer months the surf-zone species were unable to survive in all experimental treatments. Lab tests based on observed physio-chemical conditions in the marsh ponds suggest that temperature and dissolved oxygen were the primary stressors on the surf-zone fish during the summer. In other seasons of the year, species survival and fish condition were high in the absence of competition, but both indeces were significantly reduced in the competition treatments. Therefore, in summer months physical factors precluded the surf-zone fish from colonizing the ponds, but competition was actually a more important community structuring mechanism during the other three seasons. Such temporal frameworks may be useful in other aquatic habitats when trying to assess the relative importance of abiotic and biotic factors in structuring observed natural communities.
 
Day: Friday, Feb. 5
Time: 09:30 - 09:45am
Location: Eldorado Hotel
 
Code: CS57FR0930E