Presence Of Largemouth Bass Research Articles

Relative Abundance and Invasion Dynamics of Alien Fish Species Linked to Chemical Conditions, Ecosystem Health, Native Fish Assemblage, and Stream Order

The incidence and dispersal of invasive alien fish species (IAFS) have ecological impacts on biodiversity and environmental health at regional to global scales. We identified links between the presence of largemouth bass (Lb) and bluegill (Bg), and selected indicators of environmental water quality, trophic and tolerance guilds, ecological health factors, and stream order. We used the data collected from national biomonitoring study sites in four major rivers of South Korea. IAFS occurred in eutrophic waters (Lb = total phosphorus: 140 ± 170 µg/L, chlorophyll a: 16.7 ± 27.5 µg/L; Bg = total phosphorus: 160 ± 190 µg/L, chlorophyll a: 19.43 ± 28.05 µg/L) and dominated at higher ambient ratios of total nitrogen to total phosphorus (TN:TP). At TN:TP ≤ 100, the relative abundance of Lb and Bg was highest (95.3% and 96.0%, respectively). Concerning tolerance guilds, Lb (R2 = 0.78, p < 0.0001) and Bg (R2 = 0.59, p < 0.0001) had positive relationships with tolerant species in all four river watersheds and negative relationships with the percentages of insectivores and omnivores. This indicates the harmful impacts of IAFS on the aquatic food web. These invasive fish species also influenced stream health, particularly in the Nakdong and Yeongsan/Seomjin rivers. Our findings suggest that assessing chemical water quality can help identify the optimal and suboptimal survival and spread ranges of IAFS (Lb and Bg), as they directly influence tolerance and trophic guilds in the aquatic food web. In conclusion, these IAFS could be a major factor in the deteriorating ecosystem health, which had negative relationships with the abundance and occurrence of IAFS. Therefore, approaches that use appropriate water chemistry factors and species tolerance may provide critical insights into the efficient management of river health that has been perturbed by the presence of IAFS.

Collapse of a reproducing population of non-native African jewelfish (Hemichromis letourneuxi) in a Florida lake

Established populations of non-natives may collapse without a clear causal mechanism. Hypothetically, fluctuations in habitat structural complexity may influence dynamics of invaders and the biotic resistance offered by predators. Herein I report observations of the collapse of a reproducing population of the nonnative African jewelfish ( Hemichromis letourneuxi) in a Florida lake concurrent with an unusual low-water period. I test the hypothesis that predation may have played a key role in the collapse using a combination of field surveys of habitat and fish abundance and predator-prey experiments. Habitat complexity was high before and after the low water period but virtually nonexistent during low water. The abundance of African jewelfish and native juvenile bluegill ( Lepomis macrochirus) and eastern mosquitofish ( Gambusia holbrooki) declined concurrently with decreasing complexity but the native species rebounded when lake levels increased. Large-bodied natives such as largemouth bass (Micropterus salmoides) and adult bluegill showed no pattern of fluctuation related to habitat complexity. African jewelfish survival was 1.6 times greater at high versus low complexity and over 7 times higher versus no complexity in the presence of largemouth bass. Conversely, eastern mosquitofish, a species that exerts strong effects on small-bodied fishes in structurally complex habitats had no effect on African jewelfish survival. Predation effects on suscep tible non-natives should be considered as a potential control action. Population collapse is understudied but may provide insights into long-term dynamics of invaders and information useful for management of problematic species.

Gape Limitation, Prey Size Refuges and the Top–down Impacts of Piscivorous Largemouth Bass in Shallow Pond Ecosystems

Top–down control of phytoplankton biomass through piscivorous fish manipulation has been explored in numerous ecological and biomanipulation experiments. Piscivores are gape-limited predators and it is hypothesized that the distribution of gape sizes relative to distribution of body depths of prey fish may restrict piscivore effects cascading to plankton. We examined the top–down effects of piscivorous largemouth bass on nutrients, turbidity, phytoplankton, zooplankton and fish in ponds containing fish assemblages with species representing a range of body sizes and feeding habits (western mosquitofish, bluegill, channel catfish, gizzard shad and common carp). The experimental design consisted of three replicated treatments: fishless ponds (NF), fish community without largemouth bass (FC), and fish community with largemouth bass (FCB). Turbidity, chlorophyll a, cyclopoid copepodid and copepod nauplii densities were significantly greater in FC and FCB ponds than in NF ponds. However, these response variables were not significantly different in FC and FCB ponds. The biomass and density of shallow-bodied western mosquitofish were reduced and bluegill body depths shifted toward larger size classes in the presence of largemouth bass, but the biomass and density of all other fish species and of the total fish community were unaffected by the presence of largemouth bass. Our results show that top–down impacts of largemouth bass in ecosystems containing small- and deep-bodied fish species may be most intense at the top of the food web and alter the size distribution and species composition of the fish community. However, these top–down effects may not cascade to the level of the plankton when large-bodied benthivorous fish species are abundant.

Phenotypic variation and vulnerability to predation in juvenile bluegill sunfish (Lepomis macrochirus).

Bluegill sunfish (Lepomis macrochirus) are known to diversify into two forms specialized for foraging on either limnetic or littoral prey. Because juvenile bluegills seek vegetative cover in the presence of largemouth bass (Micropterus salmoides) predators, natural selection should favor the littoral body design at size ranges most vulnerable to predation. Yet within bluegill populations, both limnetic and littoral forms occur where vegetation and predators are present. While adaptive for foraging in different environments, does habitat-linked phenotypic variation also influence predator evasiveness for juvenile bluegills? We evaluate this question by quantifying susceptibility to predation for two groups of morphologically distinct bluegills; a limnetic form characteristic of bluegills inhabiting open water areas (limnetic bluegill) and a littoral form characteristic of bluegills inhabiting dense vegetation (littoral bluegill). In a series of predation trials, we found that bluegill behaviors differed in open water habitat but not in simulated vegetation. In open water habitat, limnetic bluegills formed more dense shoaling aggregations, maintained a larger distance from the predator, and required longer amounts of time to capture than littoral bluegill. When provided with simulated vegetation, largemouth bass spent longer amounts of time pursuing littoral bluegill and captured significantly fewer littoral bluegills than limnetic fish. Hence, morphological and behavioral variation in bluegills was linked to differential susceptibility to predation in open water and vegetated environments. Combined with previous studies, these findings show that morphological and behavioral adaptations enhance both foraging performance and predator evasiveness in different lake habitats.

REPLACEMENT OF RESIDENT CRAYFISHES BY AN EXOTIC CRAYFISH: THE ROLES OF COMPETITION AND PREDATION

Exotic species are often a threat to native biodiversity. In northern Wisconsin lakes, the invading crayfish Orconectes rusticus is replacing 0. virilis, the native, and 0. propinquus, a previous invader. We tested the impacts of interspecific competition for food and of nonconsumptive effects of predation by largemouth bass, Micropterus salmoides, on growth and mortality of these three species. In competition experiments, 0. virilis grew less, and 0. propinquus suffered increased mortality in the presence of 0. rusticus relative to single-species treatments. Orconectes rusticus was unaffected by the presence of con- geners. In experiments testing nonconsumptive effects of predation, 0. virilis growth de- clined substantially in the presence of largemouth bass, 0. rusticus growth declined slightly, and 0. propinquus growth was unaffected. Mortality of all three crayfishes increased in the presence of largemouth bass, with 0. virilis experiencing the greatest and 0. rusticus the least mortality. To explore how competition, predation, and their interaction influence species replace- ments, we compared a fitness index (mortality/growth = (/g) among species across biotic interaction domains: no interaction, intraspecific competition, interspecific competition, predation by fish, fish predation with competition, and predation risk with competition. In three of six domains, 0. virilis and 0. propinquus had somewhat similar (/g, but reversals in p/g rank between 0. virilis and 0. propinquus among domains occurred. These reversals are consistent with lack of unidirectionality of species replacements observed where 0. virilis and 0. propinquus distributions overlap. In all four interspecific interaction domains, 0. rusticus had the lowest (/g (indicating greatest fitness), which is consistent with observed unidirectional replacement of 0. propinquus and 0. virilis by 0. rusticus. Whereas some fish management strategies might reverse the replacement of 0. virilis by 0. propinquus, no realistic interaction domain is likely to reverse replacement of the native species by 0. rusticus.

Predator-induced delayed maturity in bluegill sunfish (Lepomis macrochirus): variation among populations.

Previous studies suggested that differences in age at maturity among populations of bluegill sunfish (Lepomis macrochirus) were not genetically based, but rather were a phenotypic response to the presence of predators. I conducted two experiments to determine if the presence of largemouth bass affected age at maturity in bluegill sunfish. Bluegills from three populations were tested to see if the response to the threat of predation varied among source populations. Juvenile bluegills were maintained in the presence of predators or in controls with no contact with predators. Refuge use and growth were monitored during the experiments and reproductive activity was evaluated when bluegills reached age 1. Bluegills from one population exhibited delayed maturity in the presence of predators. Individuals from the other two populations showed no significant differences between predator and control treatments. The population that responded to the presence of predators had a history of high predation levels over the past 30-40 years. The other populations had a history of low levels of predation. This study suggests that presence of predators can induce phenotypic shifts in age at maturity of bluegills, but that the magnitude of response varies among populations in a manner consistent with historical patterns of coexistence.

Influences of Interstice Size, Shade, and Predators on the Use of Artificial Structures by Bluegills

Abstract Adding artificial structures to lakes concentrates fish and therefore may increase angler success. However, structure characteristics that attract fish are not well understood. The purpose of this study was to evaluate the preferences of juvenile and adult bluegills Lepomis macrochirus for interstice size (40, 150, and 350 mm) within artificial structures and shaded versus unshaded structures in the absence or presence of largemouth bass Micropterus salmoides. Structures were constructed of 10-cm-diameter plastic pipes and were 1.2 m × 1.2 m × 1.5 m in size. Juvenile (50–100 mm total length, TL) and adult (>150 mm TL) bluegills consistently preferred 40-mm interstices regardless of shading or presence of largemouth bass. Most bluegills (90%) were not associated with a structure on any given day, which suggested that small structures such as ours may have a limited carrying capacity for bluegills. Use of structures by largemouth bass appeared to be related to their body size. Small individuals (<3...

Selection of Habitat Structure Interstice Size by Bluegills and Largemouth Bass in Ponds

Abstract We examined how interstice size in a structure influenced fish use of that structure. We determined preferences of bluegills Lepomis macrochirus (35–95 mm total length, TL) for small (40-mm), medium (150-mm), and large (350-mm) interstices within artificial structure units (2.5 m3) in three 0.16-hectare ponds both before and after largemouth bass Micropterus salmoides (255–454 mm TL) were added to study ponds. In the absence of predators, yearling bluegills preferred small- and medium-interstice structures over large interstices regardless of major differences in water clarity among ponds. In the presence of largemouth bass, bluegills preferred small interstices over medium and large interstices in all ponds; medium interstices were preferred over large interstices in turbid ponds but not in the clear pond. These preferences were most pronounced in the clear pond where bluegill use of medium- and large-interstice structures was halved after largemouth bass were stocked. The addition of largemouth...

Mortality and Standing Stocks of Grass Carp Planted in Two Iowa Lakes

Abstract Grass carp (Ctenopharyngoden idella) were stocked at various times in two small Iowa lakes to control the vegetation. Subsequent sampling was done by electrofishing in 1983 to determine population sizes and mortality rates. These fish grew rapidly, were long-lived, and had low annual mortality rates of 2.0-7.7%. The lowest rate occurred with plantings of age-1 fish; even the highest rate was considered low, however, because 2.5-in fingerlings were stocked in the presence of large-mouth bass (Micropterus salmoides). Grass carp plantings in Iowa lakes need to be monitored, and supplemental stocking should take place only when additional vegetation control is needed.

Experimental Study of the Impacts of Bluegill (Lepomis macrochirus) and Largemouth Bass (Micropterus salmoides) on Pond Community Structure

We examined community impacts of bluegill (Lepomis macrochirus) and largemouth bass (Micropterus salmoides) in a summer experimental pond study of factorial design with four treatment combinations (fishless, bluegill, largemouth bass, and bluegill with largemouth bass). Ceriodaphnia reticulata, Daphnia pulicaria, Chaoborus sp., Volvox sp., anisopteran and zygopteran nymphs, and dissolved oxygen levels were suppressed in the presence of bluegill. Diaptomus sp., Conochiloides sp., Cyclotellas sp., Navicula sp., Oocystis sp., Anabaena sp., Ceratium sp., algal fluorescence, turbidity, 5- to 12.7-μm particles, and total phosphorus and total nitrogen were enhanced in the presence of bluegill. Daphnia pulicaria was enhanced and Cyclotella sp. and Oocystis sp. were suppressed in the presence of largemouth bass. Although the effects of the two fish were not independent, as indicated by significant bluegill × largemouth bass interactions for some plankton taxa, we found little evidence of bluegill impacts being reversed by largemouth bass. While total bluegill biomass was reduced and bluegill biomass distributions were shifted toward larger individuals, bluegill remained abundant in the presence of largemouth bass.

Evaluation of Male Bluegill X Female Green Sunfish Hybrids for Stocking Mississippi Farm Ponds

Abstract Supplemental feeding and the presence of largemouth bass (Micropterus salmoides) had a positive influence on the size of male bluegill (Lepomis macrochirus) x female green sunfish (Lepomis cyanellus) hybrids in 12 Mississippi ponds during the first 24 months after stocking young-of-the-year hybrids. After 24 months, the size of hybrids that had supplemental feeding and were stocked without largemouth bass was similar to that of hybrids stocked with largemouth bass but without supplemental feeding. Nonfed hybrids stocked without largemouth bass were the smallest of the four group combinations; fed hybrids with largemouth bass were the largest. Largemouth bass predation reduced recruitment of F 2 hybrids by 98% relative to F1 hybrid populations without bass. Growth of these hybrids exceeded that reported for the same hybrid in Illinois ponds and was superior to that which can be expected from bluegills under typical pond conditions in Mississippi. Catchability experiments in two of the ponds confir...