Importance of behaviour to the re-establishment of drifting Ephemeroptera

Experiments with mayfly larvae in a laboratory stream revealed significant differences among settling capabilities of four species. Quantitative measures of overall settling capacity, contribution of morphology and that of behaviour were derived for comparative purposes. Importance of behaviour to re-establishment was greater in species which frequently show die1 drift periodicities than those which do not. Although morphological differences between species were large, mean size of nymphs was more important in determining rates of return of dead animals. Intraspecific vari-ations in the ability of drifting individuals to become re-estab-1ished may partially account for changes in the relative distri-bution of populations over time

Is benthic activity of stream invertebrates related to behavioral drift

NOTES 2457 and in each instance the hosts were collected during March. The occurrence of B. cuspidatus in D . cepedianum is not inexplicable since the intermediate host is a cyclopoid copepod. Dorosoma cepedianum are planktophagic fish (Jester and Jensen 1972) and readily consume cladocerans, copepods, rotifers, and numerous other zooplankton (Bodola 1965). The results of this study, therefore, provide a new host record for B. cuspidatus and also represent the first adult tapeworms ever recorded from D. cepedianum . Larval Proteocephalus tapeworms are the only other tapeworms of D. cepedianum (Hoffman 1967)

Primary Productivity in Lake Red Haw, Lucas County, Iowa

Primary production studies were conducted on an 83-acre lake in south central Iowa during the summer of 1970 and winter of 1971. Primary productivity was measured using the light­ dark bottle method. Summer values ranged from 2.74 to 6.25 grams of carbon assimilated/m2/day. This was correlated with water temperature, nitrate nitrogen, ortho phosphates, carbon dioxide, light penetration and plankton populations. Studies were continued during the winter using C14 and scintillation counting methods

The spatial organization of the peripheral olfactory organ in the round goby (Neogobius melanostomus)

Round goby (Neogobius melanostomus) spawning behaviour and parental care by males may be mediated by pheromones. We examined the spatial organization of the peripheral olfactory organ in round goby. Olfactory receptor neurons were visualized in cryostat sections stained for acetylated tubulin immunocytochemistry and by transmission electron microscopy. The olfactory epithelium is located adjacent to the tentacular anterior nostril and extends ventrocaudally along the relatively flat surface of the nasal cavity. Numerous nonmyelinated nerve fascicles formed in the lamina propria and converged into a prominent olfactory nerve. A sac-like enclosure was found on the posterior ventral surface that may regulate flow through the nares

Role of male spatial distribution and condition-dependent colouration on female spawning behaviour and reproductive success in bluegills

Female choice for male ornamental colouration has been demonstrated in a number of different taxa. Among fishes, most studies have been conducted in a laboratory setting and show that females prefer more colourful male ornaments. In this study, we observed female bluegills (Lepomis macrochirus) spawning in their natural environment and compared spawning behaviours to male traits and position within a colony. We observed spawning activities of 76 parental males in Lake Opinicon, Ontario. We captured each male and used reflectance spectrometry to objectively quantify the colour of six body regions and measured morphological characteristics. Our results show that female spawning behaviours did not significantly differ between central and peripheral males, although egg scores were higher in central nests. During spawning, females appeared to enter the nests of parental males haphazardly. However, our results suggest that male cheek colouration influenced the number of females spawning, the number of eggs they released, and the amount of time they spent in the nest. Moreover, male breast colouration significantly predicted reproductive success as quantified through egg scores. Together, our findings suggest that females may use male cheek and breast colouration, condition-dependent sexual ornaments, as key traits on which to base their mate choice decisions

Bluegill Coloration as a Sexual Ornament: Evidence From Ontogeny, Sexual Dichromatism, and Condition Dependence

In aquatic environments, visual communication is expected in animals that inhabit clear, shallow waters. Here, we investigate variation in the colorful traits of bluegills, Lepomis macrochirus, to elucidate their possible function. Bluegills use alternative mating tactics whereby males develop into one of two irreversible phenotypes termed parental and cuckolder. Parentals build and defend nests and care for offspring whereas cuckolders obtain matings by sneaking copulations. We hypothesized that bluegill coloration might function as a sexual ornament in parental males and that ornamental coloration might serve as an honest indicator of male quality. We predicted that coloration should be more pronounced in parental males than in females and immature males and should be more pronounced during the breeding season. We also predicted that males in better condition should be more intensely colored than fish in poor condition. To test our predictions, we sampled 510 bluegills during the breeding and post-breeding seasons at nine lakes in southern Ontario, Canada, in 2007. We used reflectance spectrometry to quantify the coloration of five body regions, aged and sexed each fish, and calculated Fulton’s condition factor from morphological measurements. A separate experiment showed that color did not fade several minutes post capture, suggesting that coloration could be measured reliably and consistently. We found that color was influenced by maturity, sex, and season, in the predicted direction, for three body regions (breast, cheek, and opercular flap). We also found that color varied with the condition of males such that males in better condition were darker for the sexually dichromatic ventral and facial regions. Our findings therefore suggest that some colorful traits in bluegills may serve as condition-dependent sexual signals during the breeding season. Our research contributes to a growing appreciation of the importance of visual signaling in aquatic environments