Shaw, W. H.. Sullivan County Community College, shawwh@catskill.net
Bulaveckas, P. H.. University of Louisville, pabuka01@ulkyvm.louisville.edu

 
FACTORS AFFECTING PLANKTONIC SPECIES RICHNESS IN ACIDIC LAKES
 
Collections of crustaceans and rotifers from 30 Adirondack lakes and ponds, varying in pH from 4.5 to 6.9, were evaluated to uncover the nature of the biological interactions that occur under acidic conditions. Species richness of crustaceans and rotifers, although significantly and positively correlated with pH, showed considerable variation (r2=.70). Species richness however, is not a good measure of acidification effects because acid tolerant species replace intolerant species and competition and predation may restrict the number of species, irrespective of pH. Furthermore, pH is a complex variable containing independent covariables like aluminum concentration and altered food web structure. We used the concept of species pool, defined as the number of species found in all study sites at a given pH or aluminum level to evaluate the role of aluminum toxicity. The number of species in the pool was strongly (r2=.92), linearly correlated with monomeric Al and curvilinearly correlated with pH. The curvilinear response may be due to the high variability of monomeric aluminum levels in Adirondack lakes. We also examined acidic lakes in the range of 4.1-5.3 with fish (n=14) and without fish (n=20) to evaluate the effects of altered food web structure. Acidic lakes with fish averaged about 2 more crustaceans than did lakes without fish. These findings indicate that the variability in species richness with pH may be due to inherent limitations in species richness as a response variable and variation in aluminum and altered food web structure.
 
Day: Wednesday, Feb. 3
Time: 11:15 - 11:30am
Location: Sweeney Center
 
Code: SS50WE1115S