Fish community structure, spatial distribution and feeding ecology in a beaver pond

Abstract

SynopsisThe fish community of a small (2.7 ha) Ontario beaver pond was analyzed relative to predictions based on its small size, shallow depth, brief existence and isolation from more permanent water bodies. The predictions were: (1) species richness will be lower than that of more permanent water bodies in the area, (2) fish will be mainly of small body size, (3) species will be randomly distributed across habitats, and (4) there will be a high degree of diet overlap between species and age classes. The first and second predictions were supported. The pond consisted of 10 resident species in 1985, and at least seven in 1988. Species richness was below the average of 13.2 found in four lakes in the vicinity, but greater than the 3.1 predicted by a species-area curve for non-acidified lakes in Ontario. All species except pumpkinseed, yellow perch and brown bullheads were small-bodied with short life spans and high population turnover rates, and few fish above 1OOmm were present. Predictions 3 and 4 were not supported. Habitat occupation was nonrandom, and high diet separation occurred, particularly in August when food limitation was evident. While beaver ponds lack the range of habitats and the diversity of species of lake environments, low prey density and high fish density nevertheless appear to foster resource partitioning.

Diel variation in diet composition of a riverine fish community

“…Community dietary overlap values would be further reduced if bluntnose minnow, which consumed mainly detritus and had a dissimilar diet to all other species, were incorporated in the overlap estimation. Keast (1985b) and Keast & Fox (1990) also found low dietary overlap within fish communities. Keast & Welsh (1968) and Ringler & Johnson (198 1) found that rock bass feeding activity peaked from late evening to early morning, which is consistent with our observations.…”

Allometric scaling in centrarchid fish: origins of intra- and inter-specific variation in oxidative and glycolytic enzyme levels in muscle

“…Within the sunfish pair of species, pumpkinseeds had higher glycolytic enzyme activity than bluegill, which may be part of a strategy for hypoxia tolerance (Farwell et al, 2006). Water bodies with seasonal or diurnal hypoxia often support pumpkinseed sunfish populations, but lack bluegill sunfish (Keast and Fox, 1990).…”

Can Hypoxia Tolerance Explain Differences in Distribution of Two Co-Occurring North Temperate Sunfishes?

“…Indeed, many such waterbodies experience periodic winterkills, resulting in the high mortality of fishes that are either poorly adapted evolutionarily to living in hypoxic waters, or which are unable to find a refuge from the hypoxic conditions (Magnuson and Karlen 1970;Magnuson et al 1985 and references therein). Fish species differ widely in their ability to tolerate hypoxia (see Moore 1942;Davis 1975;Melnychuk and Chapman 2002) and as a result, the fish communities that inhabit hypoxic waterbodies often differ from those that inhabit normoxic waterbodies in the same area (Tonn and Magnuson 1982;Rahel 1984;Keast and Fox 1990).…”