Diatom and protozoan community analysis and colonization on artificial substrates in lentic habitats

The purpose of this research was to examine the colonization process and relationship of physico-chemical parameters to diatom and protozoan communities colonizing polyurethane foam (PF) artificial substrates in lentic habitats. This was the first study to utilize multivariate techniques for comparison of protozoan and diatom communities

The following hypotheses were examined in this study:

1. diatom and protozoan species accrual is similar because the organisms are approximately the same size and share similar ecological conditions,
2. protozoan assemblages are influenced by the physicochemical parameters of their environment, and
3. diatoms and photosynthetic protozoans are more closely related to the physico-chemical parameters of their environment than are the protozoans of all trophic groups.

PF substrates were placed in the littoral zone of lentic habitats. Substrates were sampled through a time series and examined for their diatom and protozoan species' presence-absences. The first hypothesis was tested by using the MacArthur-Wilson equilibrium model and by fitting the data to the model by non·linear least squares regression. Protozoan species accrual fit the model in most cases, while diatom species accrual did not. The second part of the research dealt with five lentic habitats in northern lower Michigan which were sampled as described above and concurrent with organismal sampling several physico-chemical parameters were sampled. These environmental parameters included pH, alkalinity, conductivity, temperature, and concentrations of dissolved oxygen, chloride, silica, ammonia, and total and ortho-phosphate. Protozoan communities were examined using reciprocal averaging ordination. It was found that the bog and marsh had distinct communities, while the three lakes did not. Several physicochemical parameters and factors correlated significantly with axes generated by samples in species space. The final section tested the degree of relationship among diatoms, autotrophic protozoans, and protozoans to the physicochemical parameters and factors. pH had the highest correlations with the first axes for each group. Diatom communities had the greatest degree of relationship to the physico-chemical parameters, evidence for this is provided by the greatest number of correlations between ordination axes and the physico-chemical parameters and factors.