Adaptive strategies of the central mudminnow, Umbra limi (Kirtland) in southern Manitoba

Abstract

The variation in the environmental factors encountered, the habitat occupied and preferred, patterns of activity, aspects of growth, reproduction and food consumption by the central mudminnow, Umbra limi were studied to illustrate the mudminnow's adaptations to the spatial and temporal pattern of its environment. Mudminnows inhabit and show a preference for areas with cover which is consistent with their morphological, behavioural and physiological adapations. Mudminnows showed variations in time of activity. Crepuscular, nocturnal and diurnal activities were observed at different times and places. Enhanced survival of females is one of the life history strategies exhibited by mudminnows. Females (age 2+) were usually larger and more abundant than males. Age at first maturity was two for females and one for males. Time of spawning varied between years in the streams studied and some females did not spawn at all in 1979... Feeding occurred in the vegetated areas of streams. Benthic, mid-water, surface and organisms attached to vegetation were included in the diet. Mudminnows were euryphagic carnivores and ate aquatic and terrestrial invertebrates and fish (which became more important as the temperature dropped)... The central mudminnow responds to a heterogeneous environment by specializing in habitat and generalizing in time of activity, life history and feeding strategies.