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  • 1
    Electronic Resource
    Electronic Resource
    Depth equilibration of a shallow-water cichlid fish (1978)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 13 (1978), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The cichlid Melanochromis exasperatus has a natural distribution which is restricted to a single island in Lake Malawi, Africa. Diving observations indicated that it does not occur below 4.5 m depth. Measurements of depth equilibration in a pressure tank showed that males can equilibrate to a depth of 25 m and females to 18 m. Mean maximum sustained rate of depth equilibration was 2 m day−1. M. exasperatus survived a pressure decrease of 40% every 12 h from the maximum equilibration depth to the surface. The fish swim actively during the day but rest on the bottom at night when they are equilibrated to a depth 1 m deeper than ambient. Reduced activity at night is reflected in a drop in oxygen consumption to nearly half of the daytime active value.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1978.tb03488.x
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Depth equilibration by two predatory cichlid fish from Lake Malawi (1979)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 14 (1979), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The cichlid fish, Haplochromis polystigma and Haplochromis livingstonii are piscivorous ambush predators endemic to Lake Malawi, Africa. Experimentally it was found that large adult H. livingstonii could equilibrate to 38 m, but that juveniles were restricted to shallower depths. Mean depth attained by 8 H. polystigma was 45 m but two individuals exceeded the maximum simulated depth (59 m). H. livingstonii had a mean equilibration rate of 4–7 m day−1 for the first 10 m declining to 2·4 m day−1 thereafter. The mean rate of descent for H. polystigma was 3·8 m day−1 for the first 10 m and 2·8 m day−1 thereafter. The fish were decompressed at a rate of a 20% decrease every 12 h. Although cichlid fishes occur down to 200 m depth in Lake Malawi, experimental and field data indicate that the depth distribution of individual species is restricted and that the restriction is largely related to swimbladder physiology. All cichlid species so far tested equilibrate slowly to depth (2 to 5 m a day) and are not capable of rapid decompression.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1979.tb03548.x
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Cuckoo among Lake Malawi cichlid fish (1977)
    [s.l.] : Nature Publishing Group
    Nature 267 (1977), S. 243-244 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] In May 1976, during diving off Likoma and Chisumulu Islands (Lake Malawi), maternal Haplochromis polystigma Regan were found caring for mixed broods: their own offspring, easily recognised because they have adult coloration and markings from the outset, and fry of another species differing slightly ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/267243a0
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  • 4
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    African Coelacanth Ecosystem Programme: an overview of the conference contributions (2006)
    Academy of Science of South Africa
    In:  South African Journal of Science, 102 (9-10). pp. 409-415.
    Details
    Publication Date: 2020-11-09
    Description: Latimeria chalumnae is the icon for the multidisciplinary, multinational African Coelacanth Ecosystem Programme (ACEP) dedicated to improving the understanding of biological and other processes that support marine life. This article provides an overview of contributions made at a conference hosted by ACEP at the end of 2003. It also reviews significant developments regarding coelacanth conservation which have taken place since the conference. Delegates at the meeting concluded that the integrated regional,ecosystem approach that had been adopted by ACEP should continue. Underwater observation and exploration, however, should be supplemented by more experimental and technical analyses in order to answer longstanding questions related to coelacanths and other organisms.
    Type: Article , PeerReviewed
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 5
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    Oceanographic environment of the Sodwana Bay coelacanths (Latimeria chalumnae) (2006)
    Academy of Science of South Africa
    In:  South African Journal of Science, 102 (9-10). pp. 435-443.
    Details
    Publication Date: 2020-05-26
    Description: Trimix scuba divers discovered coelacanths in Jesser Canyon at a depth of 104 m on the northern KwaZulu-Natal (KZN) coast (Sodwana Bay) in October 2000. The existence of these animals at such a shallow depth and in the swift and powerful Agulhas Current led to a suggestion that this might be an isolated group swept well away from the main population in the Comoros, where they live at depths of 200-350 m with little current. Subsequent observations from three manned submersible surveys and one remotely operated vehicle expedition together with recreational diver observations indicate that the South African population of coelacanths has at least 26 individuals, mostly occupying the depth range of 104-140 m in canyons. Seventeen CTD sections collected during four cruises in 2002 and 2003 indicate the temperature range in this habitat to be similar to that found in the Comoros Islands (that is, 15-22〈sup〉o〈/sup〉C cf. 15-19〈sup〉o〈/sup〉C in the Comoros). However, a 2.5-month-long time series of hourly data collected by a thermistor array deployed near a known coelacanth cave in Wright Canyon indicated greater variation than anticipated, with temperature changes between 16〈sup〉o〈/sup〉C and 24〈sup〉o〈/sup〉C occurring in a day. Dissolved oxygen levels in this depth zone were found to range between 3.0 ml l〈sup>-1〈/sup> and 4.8 ml l〈sup>-1〈/sup> compared to 3.5 ml l〈sup>-1〈/sup> in the Comoros. The low oxygen values along this coast are a result of the shallow oxygen minimum, which becomes shallower in the southwest Indian Ocean, particularly in the Agulhas Current, than in tropical latitudes. Current velocities measured using a ship-borne ADCP in the depth range 100-140 m at Sodwana were considerably higher than those measured in the Comoros habitat (20-60 cm s〈sup>-1〈/sup> cf. 3-4 cm s〈sup〉-1〈/sup〉) and may be an important factor explaining the coelacanths' occupation of the canyons found along the northern KZN shelf-break.
    Type: Article , PeerReviewed
    Format: text
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
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