Sg. Hinch et al., SPATIAL AUTOCORRELATION AND ASSESSMENT OF HABITAT ABUNDANCE RELATIONSHIPS IN LITTORAL-ZONE FISH, Canadian journal of fisheries and aquatic sciences, 51(3), 1994, pp. 701-712
Spatial autocorrelation, wherein intersite similarity is correlated wi
th distance between sites, is a characteristic of most ecological stud
ies spanning a large environmental range. If data are spatially autoco
rrelated, classical statistical techniques provide biased estimates of
relationships between species attributes and environmental variables.
We examined abundances of seven littoral fishes in 25 lakes that vari
ed substantially in morphometry, chemistry, and elevation across centr
al Ontario. Weak correlations were observed between abundances of part
icular species and environmental variables before correcting for spati
al autocorrelation, and we hypothesized that correlations reflected sp
ecies' habitat preferences. However, spatial autocorrelation existed i
n the abiotic and fish abundance datasets. Once large-scale geographic
patterns (spatial autocorrelation) were removed using partial Mantel
tests, correlations changed within and between datasets. A strong rela
tionship emerged between abundances and lake elevation. By comparing p
atterns within geographically corrected data with those without correc
tion, we identified particular species that exhibited spatially autoco
rrelated abundances. The geographic direction of spatial autocorrelati
on provided additional insights into environmental factors also correl
ating with species abundance. We recommend that ecologists examine bot
h geographically corrected and noncorrected data when developing hypot
heses to explain regional variation in species abundance.