Morphological variation between black crappie (Pomoxis nigromaculatus) and white crappie (P. annularis) and its influence on species distribution

This is the authors' abstract. We don't add key points for this paper.

Sympatric populations of Pomoxis species display contrasting population performance along a gradient of turbidity, such that black crappie ( Pomoxis nigromaculatus ) are more abundant in clear waters and white crappie ( Pomoxis annularis ) are more abundant in turbid ecosystems. Experimental work suggests the distribution and relative abundance of Pomoxis species is driven by morphological adaptations to habitat structure and not turbidity, based on differences between age-0 black crappie and white crappie in body shape and vulnerability to predation in vegetation and open water habitats that predominate in clear water and turbid ecosystems, respectively. However, further research is needed to determine whether species-specific morphological differences are present in fish recruited to natural populations. We examined morphological traits of black crappie and white crappie collected from reservoir populations to test whether the congeners display species-specific differences in body shape throughout life. We also used long-term catch data in conjunction with surveys from fisheries biologists to test whether species dominance was related to the amount of submerged aquatic vegetation for 70 sympatric crappie populations. We found differences in morphological features between the congeners were present across reservoir crappie populations and were similar to those described for age-0 crappie. Survey data supported that black crappie were more abundant in systems with higher estimated densities of submerged aquatic vegetation, and that white crappie were more abundant than black crappie in systems with limited or no vegetation. Our results lend further support to the hypothesis that habitat-linked morphological variation influences the distribution of Pomoxis species.