Papers by Martien van Oijen
Zootaxa, 2013
The designation of a neotype for Scleropages formosus (Müller & Schlegel, 1840) by triggered a se... more The designation of a neotype for Scleropages formosus (Müller & Schlegel, 1840) by triggered a search for the type specimens of the species, which were found in the collections of the Naturalis Biodiversity Center, Leiden (RMNH) and the Natural History Museum, London (BM(NH)). The publication date of the species is corrected. Moreover, detailed data on the day of capture and the type locality were uncovered. An English translation of the major part of the original Dutch description is provided, and a number of neglected colour descriptions and figures of S. formosus are discussed. Lastly, a lectotype is designated.
ABSTRACT The recovering cichlid species in Lake Victoria provide interesting data on ecological a... more ABSTRACT The recovering cichlid species in Lake Victoria provide interesting data on ecological and morphological responses to the dramatic environmental changes in the lake. In the 1970s, the species feeding on detritus and phytoplankton made up 50% of the haplochromine ichthyomass in sub-littoral waters, and zooplanktivores 25%. However, currently the relative proportions of detritivores and zooplanktivores have reversed. Further, of these two trophic groups, only a few species recovered, some of which are now even more abundant than in the past. The dominant species seem to have expanded the range of their diet types and of habitats considerably. These changes possibly resulted in a loss of specialisation and ecological segregation. Moreover, morphological adaptations to the changed environment have been observed, e.g. a strong increase in gill surface, a change in retina structure and changes in the feeding apparatus, which seem to be in response to the decreased oxygen concentrations, the changed light conditions and the changed diet. The changes that occurred in a time span of twenty years, or about as many generations, are probably the combined results of phenotypic plasticity and natural selection. Though the dramatic ecological changes in Lake Victoria are a distressing example of the impacts of human induced perturbations, the data and material collected over the past thirty years provide excellent opportunities to study both the resilience of complex tropical ecosystems, as well as contemporary evolution in vertebrates.
Zootaxa, 2013
The presumed type status of the two remaining specimens of Peristedion moluccense Bleeker 1850 in... more The presumed type status of the two remaining specimens of Peristedion moluccense Bleeker 1850 in the collection the Naturalis Biodiversity Center was examined by comparing them to descriptions in two Bleeker papers and an unpublished manuscript by Bleeker written for the Atlas Ichthyologique. Latin, French and Dutch parts of these papers were translated into English. The Dutch description of P. laticeps Schlegel 1852 was also translated. In the course of this study it became clear why Bleeker considered P. laticeps, a as a synonym of P. moluccense.
A new species of a haplochromine cichlid (Pisces: Cichlidae: Haplochrominae) from Lake Victoria i... more A new species of a haplochromine cichlid (Pisces: Cichlidae: Haplochrominae) from Lake Victoria is described. It is the largest species known from the Mwanza gulf area before the Nile perch upsurge in 1986. Specimens have been collected between 1975 and 1985. Presumably, the species does not exist anymore and is considered to be extinct.
A new species of haplochromine cichlid from Lake Victoria, only known from the Mwanza Gulf area i... more A new species of haplochromine cichlid from Lake Victoria, only known from the Mwanza Gulf area is described.
Citation: de Zeeuw MP, Westbroek I, van Oijen MJP, Witte F (2013) Two new species of zooplanktivo... more Citation: de Zeeuw MP, Westbroek I, van Oijen MJP, Witte F (2013) Two new species of zooplanktivorous haplochromine cichlids from Lake Victoria, Tanzania. ZooKeys 256: 1-34.
The recovery of a preserved sawfish caudal fin, which turned out to be the holotype of Pristis du... more The recovery of a preserved sawfish caudal fin, which turned out to be the holotype of Pristis dubius Bleeker, 1852, prompted a review of Dr. P. Bleeker's publications on the family Pristidae. In his attempt to re-describe his original species P. zijsron and P. dubius, Bleeker made a number of mistakes that are addressed herein. Contrary to Bleeker's statement, P. zijsron and P. dubius are synonyms and the former name has priority over the latter. To make Bleeker's works on Pristis more accessible, English translations of relevant parts of his papers on Pristidae (in Dutch) and current locations of existing specimens from his original collection are provided. All existing specimens from Bleeker's original collection were also examined.
… Biology of Fishes, 1992
Ichthyological …, 2006
1 University of Miyazaki, The United Graduate School of Agricultural Sciences, Kagoshima Universi... more 1 University of Miyazaki, The United Graduate School of Agricultural Sciences, Kagoshima University, 1-1 Gakuen-kibanadai-nishi, Miyazaki 889-2192, Japan (e-mail: [email protected]) 2 National Museum of Natural History, PO Box 9517, ...
witte, f., kishe-machumu, m. a., mkumbo, o. c., wanink, J. h., goudswaard, P. c., van riJssel, J.... more witte, f., kishe-machumu, m. a., mkumbo, o. c., wanink, J. h., goudswaard, P. c., van riJssel, J.c. & van oiJen, m. J.P. The fish fauna of Lake Victoria during a century of human induced perturbations. In , by area the largest tropical lake of the world, is well-known for its diverse native fish fauna, which comprised about 500 endemic haplochromine cichlid species, two tilapiine species and 46 other species belonging to 12 families. During the past decades, the fish species diversity in the lake has declined dramatically due to human induced perturbations in the ecosystem. Based on literature and our own research findings we provide an overview of these changes and their most likely causes. During the first half of the last century, the increasing fishing pressure had a great impact on the native tilapiine cichlids and other large fish species. The shift in fish landings showed a classic example of fishing down the food web. Because of the dwindling catches, the Nile perch and four exotic tilapiine cichlids were introduced into the lake in the 1950s. Dramatic changes in the fish fauna occurred in the 1980s, with the upsurge of the introduced Nile perch and Nile tilapia, the decline of wetland zones, and increased eutrophication of the lake. The native tilapiines were replaced by the Nile tilapia, and several of the catfish species showed a dramatic decline, as did the lungfish. Most severely hit were the haplochromine cichlids, which disappeared from large parts of the lake, probably resulting in the extinction of many species. The introduced Nile perch and Nile tilapia, and the native cyprinid Rastrineobola argentea became the dominant fish species. Though water quality deteriorated and fish diversity decreased, fish landings rose from about 100,000 t y -1 in the 1970s to approximately 1 million t y -1 in the period 2005-2007. Since 1999 the biomass of Nile perch declined, whereas that of R. argentea increased. In the same period some of the sublittoral haplochromine species have recovered. Some of the surviving fish species, show remarkable changes in ecological and morphological features relative to the pre-Nile perch period, which seem to be adaptive responses to the changed environment. Although it may be possible to reconcile fisheries sustainability with biodiversity conservation in the lake basin, measures to reduce environmental stress in the lake are an urgent issue. lake victoria's fish fauna during the Past century -witte et aL.
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Papers by Martien van Oijen