Rago, P. J., and Wiener, J. G., 1986, Does pH affect fish species richness when
lake area is considered?: Transactions of the American Fisheries Society, v. 115,
no. 3, p. 438-447.

Abstract:

Numerous surveys have shown that fish species richness (number of species) is
positively correlated with  lake pH. However, species richness of fish communities
is also correlated with lake size, and low-pH lakes are  often small. Thus,
conclusions drawn from examination of fish community structure relative to spatial
(among- lake) variation in pH have been limited by uncertainties regarding the
confounded effects of lake area. The  authors used two statistical methods, analysis
of covariance and a nonparametric blocked comparison test, to  remove effects of
lake area and compare fish species richness in low-pH and high-pH lakes. Data
from six  previous surveys of water chemistry and fish communities in lakes of
Ontario and northern Wisconsin were  examined. Lakes with low pH ( less than or
equal to  6.0) contained significantly fewer fish species than lakes  with high pH (>
6.0) when the effect of lake area was considered. A simple probabilistic model
showed that the  ability to detect differences in species richness is low when lake
areas and the pool of potential colonizing species  are small. The authors
recommend the blocked comparison test for separating the effects of lake area and
pH on  species richness.

Keywords:

water-pH, species-richness, community-structure, lakes, pH-effects,
species-diversity, Pisces, population-dynamics, Canada,-Ontario, USA, Wisconsin,
area