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  • 1
    Electronic Resource
    Electronic Resource
    Habitat use by the African anabantid fish Ctenopoma muriei: implications for costs of air breathing (2004)
    Oxford, UK : Munksgaard International Publishers
    Ecology of freshwater fish 13 (2004), S. 0 
    Details
    ISSN: 1600-0633
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract –  This study examined whether habitat use by the African anabantid fish Ctenopoma muriei is consistent with predictions relating to two costs of air breathing (surface travel and aerial predation). We predicted that C. muriei would be most abundant in habitats that minimize potential costs of air breathing. We quantified environmental correlates of C. muriei abundance within a series of wetland lagoons in Uganda and found that C. muriei was more abundant in shallow waters of the deepest lagoon, in vegetated habitats, and at a depth 15–30 cm below the surface. These locations may minimize cost of travel to the surface for aerial respiration, while maintaining a reasonable distance from the surface to avoid detection by aerial predators. In addition, we experimentally tested effectiveness of vegetative cover in reducing mortality of C. muriei by aerial predators (pied kingfishers) using enclosures with and without vegetation cover in a swamp pool. We found that the presence of vegetative cover significantly reduced susceptibility of C. muriei to predation by pied kingfishers when dissolved oxygen in the water was low and air-breathing frequency was potentially high.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.0906-6691.2004.00034.x
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  • 2
    Electronic Resource
    Electronic Resource
    Fish populations in tropical floodplain pools: a re-evalution of Holden's data on the River Sokoto (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Ecology of freshwater fish 2 (1993), S. 0 
    Details
    ISSN: 1600-0633
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract– In this study we asked whether the fish populations of residual pools in a seasonally fluctuating African river varied between years. We used a series of data on the fish of the permanent floodplain pools of the River Sokoto, Nigeria compiled by M. J. Holden (1963) to address this objective. Holden provided estimates for the size and biomass of fish populations in 12 permanent dry season pools over a period of 2 to 3 years. On average, only 22% of the species present in a pool were absent from that pool in the following sampling period. Despite low interannual variability in the species composition of the pools, rank correlation analysis indlcated significant variation in the relative numbers and biomass of the 10 most numerically abundant species in most pools. Altering the spatial scale of analysis to include all possible combinations of 2 and 6 pools did not affect the results. Indices of similarity also indicated relatively high annual variability in the relative abundance of species in the pool communities. We suggest that habitat selection may contribute to the continued occurrence of fish species in pools from year to year, and such factors as changes in the overall abundance of fish species in the system and haphazard trapping during flood decline may contribute to annual variation in their relative abundance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-0633.1993.tb00013.x
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  • 3
    Electronic Resource
    Electronic Resource
    Seasonal dynamics of habitat use by an airbrathing catfish (Claris liocephalus) in a papyrus swamp (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Ecology of freshwater fish 4 (1995), S. 0 
    Details
    ISSN: 1600-0633
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: I examined the effects of extreme hypoxia and water level fluctuations on the distribution and movement of an air-breathing clariid catfish, Clarias liocephalus, in a papyrus swamp in western Uganda. Monthly records of the distribution and relative abundance of C. liocephalus across 28 swamp stations were used to examine seasonal trends in habitat use and movement. My results suggest that dissolved oxygen did not directly limit use of, or dispersal through, the papyrus swamp. C. liocephalus were found at most stations in the dry season, and there was no significant relationship between the number of stations used per month and mean monthly dissolved oxygen levels. In addition, there was no evidence for a significant effect of oxygen on the relative abundance of fish among stations during the driest months, or during peak flood conditions. However, relative abundance was positively correlated with water depth during the dry season. Fish from deeper habitats exhibited fewer injuries and lower rates of disappearance than fish from shallower waters. This may reflect the risk of aerial predation for surfacing fish. A comparison of habitat use and movements of C. liocephalus with the only other fish species found in the papyrus swamp, Barbus neumayeri, supports the idea that respiratory mode can affect the use of hypoxic papyrus swamps. B. neumayeri, is a small water-breathing cyprinid that uses aquatic surface respiration in response to severe hypoxia. The air-breathing capabilities of C. liocephalus permitted more widespread use of swamp waters than B. neumayeri. This study demonstrates that an understanding of the respiratory mode of fish species may be useful in predicting patterns of habitat use.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-0633.1995.tb00124.x
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  • 4
    Electronic Resource
    Electronic Resource
    Respiratory oxygen consumption among groups of Pseudocrenilabrus multicolor victoriae subjected to different oxygen concentrations during development (2002)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 61 (2002), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The routine metabolic rate of Pseudocrenilabrus multicolor victoriae, laboratory-reared, F1 offspring of parents collected from a hypoxic swamp, did not differ between sibs raised under normoxia and hypoxia. In the offspring of parents originating from a river where the oxygen levels were generally high but fluctuating, the metabolic rate of fish raised under normoxia was higher than for sibs raised under extreme hypoxia. Although further experiments with a larger random sample of the parental stock will be necessary to validate the patterns, the difference between the experiments may indicate the selective environment of the parents.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.2002.tb01749.x
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  • 5
    Electronic Resource
    Electronic Resource
    Respiratory characters of three species of haplochromine cichlids: Implications for use of wetland refugia (2000)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 57 (2000), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Respiratory characters of three east African haplochromine cichlid species that differ in their use of hypoxic wetlands were examined to consider the potential of dissolved oxygen as one factor affecting habitat use. All three species had a large gill surface area, ranging from the 67th (Pseudocrenilabrus multicolor victoriae) to 98th (Astatotilapia velifer) percentile of the known gill size range for freshwater fishes. Pseudocrenilabrus multicolor victoriae was the most tolerant to hypoxia exhibiting the lowest aquatic surface respiration (Rs)thresholds and lowest critical oxygen tension of the three species. Astatotilapia velifer had the highest ASR thresholds, gill ventilation rates, and level of surface activity of the three species, indicating a relatively low tolerance to hypoxia. Prognathochromis venator was intermediate in its response to hypoxia. These findings are discussed in light of survivorship and distribution patterns of these species following Nile perch introduction into Lake Nabugabo.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.2000.tb02187.x
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  • 6
    Electronic Resource
    Electronic Resource
    Hypoxia and interdemic variation in Poecilia latipinna (2004)
    Oxford, UK; Malden, USA : Blackwell Science Ltd
    Journal of fish biology 65 (2004), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Variation in respiratory traits was quantified between two populations of the sailfin molly Poecilia latipinna(one from a periodically hypoxic salt marsh, Cedar Key, and one from a chronically normoxic river site, Santa Fe River). Two suites of characters were selected: traits that may show both short-term acclimation response and interdemic variation in acclimation response (metabolic rate, critical oxygen tension and respiratory behaviour), and those that are not likely to respond to short-term acclimation but may vary among populations (gill morphometric characters). Sailfin mollies from the salt marsh, acclimated to hypoxia (1 mg l−1, c. 20 mmHg) for 6 weeks, spent less time conducting aquatic surface respiration and had lower gill ventilation rates than hypoxia-acclimated conspecifics from the well-oxygenated river site. Poecilia latipinna acclimated to hypoxia exhibited a lower critical oxygen tension (Pc) than fish acclimated to normoxia; however, there was also a significant population effect. Poecilia latipinna from Cedar Key exhibited a lower Pc than fish from the Santa Fe River, regardless of acclimation. Cedar Key fish had a 14% higher mean gill surface area relative to fish from the Santa Fe River, a character that could account, at least in part, for their greater tolerance to hypoxia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.0022-1112.2004.00474.x
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  • 7
    Electronic Resource
    Electronic Resource
    Papyrus swamps, hypoxia, and faunal diversification: variation among populations of Barbus neumayeri (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 54 (1999), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: To test whether patches of papyrus swamp contribute to diversification of populations of non-air-breathing fishes, the gill morphology of Barbus neumayeri was compared between a papyrus swamp and several tributaries which differed in oxygen regime. Total gill filament length differed among sites and was negatively related to dissolved oxygen availability, supporting strong selection pressure for low-oxygen tolerance in the swamp interior. Among recaptures of marked B. neumayeri over a 4·5-year period among the focal swamp and connected stream and river sites, 93% of fish were recovered at the site of capture. Some of the individuals that moved crossed physicochemical gradients and traversed long distances within the swamp/stream system. This movement rate would theoretically be sufficient to homogenize gene frequencies among populations. However, randomly amplified polymorphic DNA (RAPD) markers indicated significant genetic differentiation among sites and no relationship between genetic differences and geographical distances among sites suggesting habitat-specific selection pressures on dispersers, rather than insufficient dispersal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1999.tb00832.x
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  • 8
    Electronic Resource
    Electronic Resource
    Interdemic variation in haematocrit and lactate dehydrogenase in the African cyprinid Barbus neumayeri (2004)
    Oxford, UK; Malden, USA : Blackwell Science Ltd
    Journal of fish biology 65 (2004), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: This study evaluated whether the African cyprinid Barbus neumayeri from Rwembaita Swamp (low-oxygen) and Njuguta River (high-oxygen) in the Kibale National Park, Uganda differed in traits related to aerobic and anaerobic metabolic potential. Haematocrit was measured as an index of blood oxygen-carrying capacity, and tissue activities and isozyme composition of lactate dehydrogenase (LDH) were measured as indices of tissue anaerobic capacity. To address whether site-dependent differences were acute responses v. longer-term adjustments to environmental conditions, these variables were measured in fish sampled shortly after collection and after laboratory maintenance under well-aerated conditions. In fish sampled in the field, those from the low-oxygen site had significantly higher haematocrit, but this difference disappeared after long-term laboratory maintenance. In contrast, fish from the low-oxygen site had higher liver LDH activities than fish from the high-oxygen site, and this difference persisted during laboratory maintenance. Polymorphism was detected at both the LDH-A and LDH-B loci, and genotype frequencies for LDH-B differed significantly between collection sites. These results demonstrate physiological, biochemical and genetic differences in B. neumayeri from habitats differing in dissolved oxygen availability and suggest both acute and long-term responses to local environmental conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.0022-1112.2004.00515.x
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  • 9
    Electronic Resource
    Electronic Resource
    Air-breathing behaviour of the African anabantoid fish Ctenopoma muriei (2005)
    Oxford, UK; Malden, USA : Blackwell Science Ltd
    Journal of fish biology 67 (2005), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Frequency of aerial respiration in Ctenopoma muriei increased as dissolved oxygen (DO) decreased; breathing behaviour was spatially synchronous, and there was no difference in air-breathing frequency between populations from a high- and low-DO site. Although C. muriei survived without access to the surface, its loss of buoyancy and equilibrium under these conditions suggested that it is a functionally obligatory air breather.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.0022-1112.2005.00725.x
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  • 10
    Electronic Resource
    Electronic Resource
    Hypoxic wetland tributaries as faunal refugia from an introduced predator (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Ecology of freshwater fish 8 (1999), S. 0 
    Details
    ISSN: 1600-0633
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract– The introduction of Nile perch (Lates niloticus) into the Lake Victoria basin of East Africa has coincided with the decline or disappearance of hundreds of indigenous species. To mitigate additional biodiversity loss, we must learn what limits the spread of Nile perch and what habitats serve as refugia for prey species. Heavily vegetated wetlands may protect fishes from Nile perch predation by providing both structural and low-oxygen refugia for prey species tolerant of hypoxia. To examine the potential of wetlands as refugia we quantified the composition, persistence, and stability of fish assemblages in a wetland tributary of Lake Nabugabo, a satellite lake of Lake Victoria in which Nile perch have been introduced. Nile perch were extremely rare in the wetland, and nine of the 18 species that have disappeared from the open waters of the satellite lake were captured in the tributary in this study. Dissolved oxygen was chronically low in the river and may be important in shaping fish community characteristics. Faunal attenuation occurred as the dry season progressed and oxygen levels dropped; however, the most common species remained through seasonal changes. The chronically low oxygen conditions in the werland tributary may permit persistence of only hypoxia-tolerant species. However, wetland conditions seem to limit exploitation by Nile perch providing critical refugia for a subset of the basin fauna.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-0633.1999.tb00049.x
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