Experimental and Field Evidence for Inter- and Intraspecific Competition in Two Freshwater Fishes

1985 ◽  
Vol 42 (2) ◽  
pp. 280-286 ◽  
Author(s):  
John Mark Hanson ◽  
William C. Leggett
Keyword(s):  
Interspecific Competition ◽  
Weight Change ◽  
Intraspecific Competition ◽  
Littoral Zone ◽  
Yellow Perch ◽  
Lepomis Gibbosus ◽  
Field Evidence ◽  
Behavioural Interactions ◽  
Natural Density ◽  
Growth Changes

Direct evidence for intra- and interspecific competition in fishes was obtained by manipulating populations of yellow perch (Perca flavescens) and pumpkinseed (Lepomis gibbosus) stocked into littoral zone enclosures. Stocking densities were above, below, and equal to measured littoral zone fish biomass. There were no significant differences in mean percent weight change at given densities among repeated experiments (each of 14-d duration). In experiments testing for intraspecific competition, all fish reared at low density gained weight, all fish reared at high density lost weight, and mean weight change at natural density did not differ from 0.0. In experiments testing for interspecific competition, growth of pumpkinseed did not differ from growth of pumpkinseed reared alone at equivalent densities whereas growth of yellow perch was depressed relative to growth of yellow perch reared alone at equivalent densities. These growth changes did not result from behavioural interactions. We conclude that (a) inter- and intraspecific competition for food is significant at natural fish densities and (b) pumpkinseed are superior to perch when competing for food. A marked reduction in yellow perch growth in Lake Memphremagog between 1972 and 1983, coincident with a major increase in pumpkinseed abundance, is consistent with these findings and our interpretations.

Effect of Competition Between Two Freshwater Fishes on Prey Consumption and Abundance

1986 ◽  
Vol 43 (7) ◽  
pp. 1363-1372 ◽  
Author(s):  
John Mark Hanson ◽  
William C. Leggett
Keyword(s):  
Interspecific Competition ◽  
Intraspecific Competition ◽  
Littoral Zone ◽  
Yellow Perch ◽  
Perca Flavescens ◽  
Lepomis Gibbosus ◽  
Fish Biomass ◽  
Gut Fullness ◽  
Total Fish ◽  
Food Consumed

The effect of inter- and intraspecific competition on the type and quantity of food consumed by fish, and on the abundance of macroinvertebrate prey, was examined by manipulating densities of yellow perch (Perca flavescens) and pumpkinseed (Lepomis gibbosus) stocked into littoral zone enclosures at levels approximating 0.5, 1.0, and 2.0 times the measured total fish biomass on the littoral zone. In intraspecific competition experiments, neither species showed a change in the type of prey eaten (principally macroinvertebrates). The amount of food eaten by yellow perch reared at high (26 g/m2) densities was significantly depressed relative to that of perch reared at low (6.5 g/m2) and natural (13 g/m2) densities. There were no significant differences in the amount of food eaten by pumpkinseed at the three fish densities. The gut fullness of pumpkinseed reared at high densities, however, was biased to a significant but unknown degree by the inclusion of a nonfood item, macrophyte fragments, in the estimates. No other fish consumed macrophytes. In interspecific competition experiments, the gut fullness of yellow perch and pumpkinseed reared together (combined density 13 g/m2) did not differ from that of fish reared alone at low or natural densities. The diet (principally macroinvertebrates) of the superior competitor, pumpkinseed, did not change relative to that of pumpkinseed reared alone. The inferior competitor, yellow perch, exhibited a significant change in diet. Microcrustaceans (an energetically inferior food) comprised 30–53% of the diet (by weight) of yellow perch reared with pumpkinseed compared with < 1% of the diet of perch reared alone. Total macroinvertebrate biomass and abundance were unaffected by differences in fish biomass in the enclosures.

Feeding Interrelations Between Age-Groups of Pumpkinseed (Lepomis gibbosus) and Comparisons with Bluegill (L. macrochirus)

1978 ◽  
Vol 35 (1) ◽  
pp. 12-27 ◽  
Author(s):  
Allen Keast
Keyword(s):  
Key Words ◽  
Interspecific Competition ◽  
Intraspecific Competition ◽  
Spatial Ecology ◽  
Prey Size ◽  
Age Groups ◽  
Lepomis Gibbosus ◽  
Young Fish ◽  
Chironomid Larvae ◽  
Class Separation

Analysis of the stomachs of 2435 pumpkinseeds (Lepomis gibbosus) showed that the diet was made up largely of chironomid larvae, molluscs, isopods, with lesser quantities of amphipods, Trichoptera larvae, and Ephemeroptera nymphs. Cladocera were only important to the very young fish. Age-class separation, in terms of taxonomic and prey-size categories, was minor, although the diet changed somewhat with age. Quantification of the diet overlaps between year-classes (by Levins index) revealed overlap levels that were moderate to high, varying seasonally between 0.5 and 1.1. They were greatest in July when the diversity of available prey organisms fell and October when several size-classes simultaneously consumed isopods, then at a peak in biomass. The feeding and spatial ecology of the pumpkinseed was compared with that of a closely related congener, the bluegill (L. macrochirus). The two species and their equivalent year-classes separated out partially on diet (the bluegill consuming a greater proportion of Cladocera and Tnchoptera larvae; the pumpkinseed, molluscs and isopods), and partly on habitat and the height at which they foraged in the water column. Ecological overlap values between equivalent year-classes of the two species were moderate, 0.52–0.57 (Levins scale), on the basis of diet alone as well as when the habitat component was incorporated. It is suggested, however, that other differences serve to reduce these levels. Key words: feeding, year-class diets, sunfish, intraspecific competition, interspecific competition, prey invertebrates, Centrarchidae

Competition betweenElymus elymoidesandTaeniatherum caput-medusae

Weed Science ◽  
1999 ◽  
Vol 47 (6) ◽  
pp. 720-728 ◽  
Author(s):  
David W. Clausnitzer ◽  
Michael M. Borman ◽  
Douglas E. Johnson
Keyword(s):  
Soil Moisture ◽  
Interspecific Competition ◽  
Seed Production ◽  
Intraspecific Competition ◽  
Field Experiments ◽  
Block Design ◽  
Low Oxygen ◽  
Competitive Effects ◽  
Growing Seasons ◽  
Randomized Block Design

Two field experiments were conducted from 1993–1994 through 1995–1996 growing seasons in Harney County, OR, to determine the relative competitive abilities ofElymus elymoides(squirreltail) a native perennial range grass, andTaeniatherum caput-medusae(medusahead), an exotic annual grass weed. The 1993–1994 growing season was very dry, 1994–1995 was dry, and 1995–1996 was wetter than average. One experiment tested seedlings vs. seedlings in each of three seasons. The second experiment tested seedlings plus second- and third-year establishedE. elymoidesplants vs. 77caput-medusaeover 2 yr. Biomass, seed production, and soil moisture utilization 15, 30, 45, and 60 cm deep by the two species were measured. A randomized block design with factorial arrangement was used, with 25 2.25-m2plots per block. Initial seeding densities of each species were 0, 10, 74, 550, and 4,074 seeds m−2in all combinations of density. In the seedling vs. seedling experiment, intraspecific competition by 77caput-medusaeon itself was always significant (P ≤ 0.10) for both biomass and seed production. Interspecific competition byE. elymoidesseedlings onT. caput-medusaebiomass and seed production was not significant (P ≥ 0.10) in 2 of 3 yr and was always less than intraspecific competition by 77caput-medusae. Only 0.4% ofE. elymoidesseed germinated, and no seed was produced in the very dry first year, but 84% of remaining seed was viable for the next year, which had better moisture conditions for germination and establishment. Interspecific competition affected (P ≤ 0.10)E. elymoidesseedling biomass and seed production throughout the study. Intraspecific competition affected (P ≤ 0.10) seedlingE. elymoidesseed production in the dry year but not in the wetter than average year. In the matureE. elymoidesexperiment, intraspecific competition byT. caput-medusaeon weight and seed production per plant was greater than interspecific competition fromE. elymoides. Seedling/matureE. elymoidesreducedT. caput-medusaeweight per plant in the dry year but the effect was not biologically significant. Larger, matureEelymoidesplants produced 600 to 3,000 seeds per plant during the wet year; neither intra- nor interspecific competition was a factor.Taeniatherum caput-medusaewas better able to access deeper soil moisture and was more aggressive at extracting soil moisture than wereE. elymoidesseedlings in the wet year. Cold soils and low oxygen due to wet soils may have restrictedE. elymoidesseedling root activity. MatureE. elymoidesplants did not appear restricted by cold soils or low oxygen. Established second- and third-yearE. elymoidesplants were able to compete for soil moisture down to 45 cm. The generally greater interspecific competitive effects ofT. caput-medusaeonE. elymoidesthan vice versa suggested that it will be difficult to establish anE. elymoidesstand in an existingT. caput-medusaecommunity without first suppressingT. caput-medusae. IndividualE. elymoidesplants did establish and were productive with and withoutT. caput-medusaecompetition.

Plant Water Stress of Soybean (Glycine max) and Common Cocklebur (Xanthium pensylvanicum): A Comparison Under field Conditions

Weed Science ◽  
1979 ◽  
Vol 27 (3) ◽  
pp. 285-289 ◽  
Author(s):  
H. D. Scott ◽  
R. D. Geddes
Keyword(s):  
Glycine Max ◽  
Water Stress ◽  
Interspecific Competition ◽  
Intraspecific Competition ◽  
Vegetative Growth ◽  
Species Differences ◽  
Plant Water ◽  
Plant Water Stress ◽  
Diffusive Resistance ◽  
Early Afternoon

The study was conducted to determine the seasonal and diurnal water stress of soybeans [Glycine max (L.) Merr. ‘Lee 74′] grown under intraspecific competition (competition between plants of the same species) and interspecific competition (competition between plants of different species) with common cocklebur (Xanthium pensylvanicum Wallr.). Midday xylem potentials decreased as the season progressed and were lower in common cocklebur during vegetative growth of soybean and in soybean during reproductive growth. For a given species differences in xylem potential due to mode of competition were small. In the diurnal studies xylem potential for each species decreased to a minimum in the early afternoon but recovered to the original pre-dawn values at night. As the season progressed leaf xylem potential (a) decreased at a greater rate, (b) decreased sooner in the day, and (c) recovered at a slower rate. It was shown that differences in xylem potential between soybean and common cocklebur on a given day were small. Greater diffusive resistance values generally were found with soybean than with common cocklebur and with each species grown under interspecific competition.

Competition between endoparasitic nematodes and effect on biomass of Ammophila arenaria (marram grass) as affected by timing of inoculation and plant age

Nematology ◽  
2005 ◽  
Vol 7 (2) ◽  
pp. 169-178 ◽  
Author(s):  
Wim van der Putten ◽  
Henk Duyts ◽  
E. Pernilla Brinkman
Keyword(s):  
Interspecific Competition ◽  
Intraspecific Competition ◽  
Plant Biomass ◽  
Nematode Species ◽  
Pratylenchus Penetrans ◽  
Agricultural Systems ◽  
Ammophila Arenaria ◽  
Marram Grass ◽  
Natural Dune ◽  
Dune Grass

AbstractWe studied the effects of intra- and interspecific competition on the abundance of endoparasitic nematodes and assessed the consequences for biomass production of the natural dune grass Ammophila arenaria. Pratylenchus penetrans was limited by intraspecific competition and it suppressed the abundance of Heterodera arenaria, whilst the interaction between H. arenaria and Meloidogyne maritima was neutral. Pratylenchus penetrans and H. arenaria reduced plant biomass, whereas M. maritima did not. Plant biomass was not differently affected by adding one or two nematode species. When added to older plants, numbers of H. arenaria and M. maritima were higher but numbers of P. penetrans were lower, resulting in less reduction of plant biomass. We discuss our results on this natural system with respect to patterns of interspecific nematode competition observed in agricultural systems.

Littoral Fish Communities in Southern Quebec Lakes: Relationships with Limnological and Prey Resource Variables

1994 ◽  
Vol 51 (5) ◽  
pp. 1128-1138 ◽  
Author(s):  
Clay L. Pierce ◽  
Joseph B. Rasmussen ◽  
William C. Leggett
Keyword(s):  
Species Richness ◽  
Fish Species ◽  
Yellow Perch ◽  
Fish Communities ◽  
Principal Component ◽  
Lepomis Gibbosus ◽  
Fish Biomass ◽  
Littoral Fish ◽  
Total Fish ◽  
Invertebrate Biomass

We assessed species richness, biomass, and community type of littoral fish in 10 southern Quebec lakes in relation to several limnological and prey resource variables. Lake, yearly, and seasonal variation in biomass was evaluated by quantitative, replicated seining. Species richness averaged 12.8 in our lakes, and 24 species were collected overall. Total littoral fish biomass averaged 13.5 g∙m−2 overall and varied significantly among lakes (range 6.1–26.9 g∙m−2) and between early and late summer. Yellow perch (Perca flavescens), golden shiner (Notemigonus crysoleucas), and pumpkinseed (Lepomis gibbosus) occurred in all lakes and were the most abundant species overall, averaging 57% of the total fish biomass. Principal component ordination of littoral fish communities showed little evidence for aggregation of community types. Species richness was positively correlated with lake surface area (r2 = 0.62), as has been shown in other studies. Total fish biomass was positively correlated with biomass of chironomids (r2 = 0.57), which constituted 24% of the littoral invertebrate biomass in our lakes and are important prey of many fish species. We found no significant correlation between total fish biomass and total invertebrate biomass or between biomass of any of the dominant fish species and limnological or prey variables.

Distribution, Abundance, and Resource Utilization of Littoral Zone Fishes in Response to a Nutrient/Production Gradient in Lake Memphremagog

1977 ◽  
Vol 34 (8) ◽  
pp. 1105-1117 ◽  
Author(s):  
Dominique Gascon ◽  
William C. Leggett
Keyword(s):  
Interspecific Competition ◽  
Resource Utilization ◽  
Fish Species ◽  
Littoral Zone ◽  
Individual Species ◽  
Food Utilization ◽  
Fish Food ◽  
Gradient Distribution ◽  
Northern Areas ◽  
Fundulus Diaphanus

The abundance and distribution of six littoral zone fish species (Notropis volucellus, Hybognathus nuchalls, Notemigonus crysoleucas, Pimephales notatus, Fundulus diaphanus, and Etheostoma nigrum) in Lake Memphremagog were influenced directly by a nutrient-driven production gradient existing along the long axis of the lake. The biomass of the six littoral zone fish species was approximately 3 times greater in the more productive southern areas than in the less productive northern areas. Interspecific competition for food was more intense in the less productive northern areas than in the more productive southern areas, and strongly influenced the patterns of food utilization. However, interspecific competition did not appear to play the major role in determining the distribution of the species on the gradient. Distribution of individual species was principally governed by the relative abundance of preferred food resources. The distribution of only one species, Fundulus diaphanus, appeared to be determined primarily by direct competition. Key words: littoral zone, Lake Memphremagog, nutrients, production, resource utilization, fish, food availability

Epizootiology, pathology, and description of Eustrongylides tubifex (Nematoda: Dioctophymatoidea) in fish

1988 ◽  
Vol 66 (10) ◽  
pp. 2212-2222 ◽  
Author(s):  
Lena N. Measures
Keyword(s):  
Yellow Perch ◽  
Perca Flavescens ◽  
Infected Fish ◽  
Lepomis Gibbosus ◽  
Fourth Stage ◽  
Intermediate Hosts ◽  
Third Stage ◽  
Rock Bass ◽  
Ambloplites Rupestris ◽  
Fish Hosts

In Guelph Lake, a man-made reservoir in Ontario, Canada, prevalence of larval Eustrongylides tubifex in pumpkinseed (Lepomis gibbosus), rock bass (Ambloplites rupestris), and yellow perch (Perca flavescens) was 12.9% and mean intensity ranged from 1 to 1.8. Larvae were encapsulated on the mesentery of fish. Pumpkinseed and yellow perch were the important fish hosts in Guelph Lake as most larvae in these fish were alive. In contrast, 40% of larvae in rock bass were dead and calcified. Third- and fourth-stage larvae from naturally infected fish are described. Larvae in the three species of fish elicited a granulomatous inflammatory reaction. Attempts to transfer third-stage larvae from experimentally infected oligochaetes and third-stage larvae from naturally infected fish to laboratory-reared pumpkinseed were unsuccessful. Fourth-stage larvae from naturally infected fish were transferred successfully to pumpkinseed. Eutropic lakes such as Guelph Lake are particularly suitable enzootic areas because of the abundant populations of tubificid intermediate hosts and the presence of fish hosts such as pumpkinseed and perch. The advanced stage and development of larvae (to the fourth stage) in fish likely represents an adaptation for a parasite that occurs in a migratory host such as Common Mergansers (Mergus merganser), which frequent Guelph Lake for only about 1 month in spring and fall.

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