RECENT DISTRIBUTION PATTERNS OF LUBOMIRSKIIDAE IN LAKE BAIKAL AND IMPLICATIONS ON SPICULE-ALLOCATIONS IN FOSSIL SEDIMENTS
IMAGE PROCESSING AND CLOSE-RANGE PHOTOGRAMMETRY AS METHODS TO SURVEY SESSILE AQUATIC ORGANISMS IN DIVABLE DEPTHS
Autor: Bonse, Dirk; Korduan, Peter
In:

Third International Symposium
Series of the International Symposiums: Speciation In Ancient Lakes (SIAL)
Herausgeber: SIBERIAN DIVISION OF RUSSIAN ACADEMY OF SCIENCES, BAIKAL INTERNATIONAL CENTER FOR ECOLOGICAL RESEARCH (BICER), LIMNOLOGICAL INSTITUTE SD RAS (LIN SD RAS) AND BAIKAL MUSEUM SD RAS (BM SD RAS)
Sachtitel_Bandes: Ancient Lakes: Speciation, Development in Time and Space, Natural History
Ort: Venue: Irkutsk, Russia
Jahr: 2002

Einordung:
Institut: Professur Geodäsie und Geoinformatik

Abstract:
The endemic sponge family Lubomirskiidae is – regarding the biomass with up to 1 kg/m2 (KOZHOW 1963) – an important benthic community of Lake Baikal. At least since the early Miocene exists a fossil record of Lubomirskiidae, as described e.g. by MARTINSON 1954. The variation of fossil spicule allocations in sediments during time has proven to be a significant paleo-ecological indicator by Weinberg et al. 1999 on sediment short-cores ranged until the lower Pleistocene boundary.
In order to compare recent with extant distribution patterns of sponges more informations on present sponge-socialisations are necessary. Within the current DFG-sponsored project “Paleo-ecologic Development in Ancient Lakes – Reconstruction based on Sponge Socialisations in Lake Baikal” several computer-aided methods and experimental field-investigations has been implemented. Apart from the transfer experiments, one basic idea was to survey the sponges as contact-free as possible to not disturb their natural development.
Groundwork is the digital mapping of especially incrusting sponge communities in photographed 30x30 cm plots. Measuring the relative and absolute covering of the different sampled species within a surveyed community has been carried out using a Geographical Information System. Until now, 12 transects, located in the southern and central part of Lake Baikal has been accomplished.
Supported by the Rollei GmbH, a german company for metric cameras and photogrammetric software solutions, a method of precise three dimensional reconstructions of L. baicalensis using close-range photogrammetry is evolved to determine an annual growth rate. These reconstructions allow accurate size measurements on sessile organisms with a deviation less than 1mm – this is necessary because annual photographic observations of some specific L. baicalensis showed an annual growth rate less than at least 1 cm.
The transfer experiments of selected sponges to different bathymetric habitats with varying ecologic parameters (light, substrate, food supply) should help to illuminate the range of environmental conditions that a particular sponge is able to handle. During the ongoing research regarding the abundance of the baikalian sponges at different times this might give considerations on possible environmental circumstances that causes particular socialisations of sponges at a certain geologic time unit.
Literature cited:
KOZHOW, M., 1963. Lake Baikal and its life. The Hague, 344 pp.
Martinson, G. G., 1954. A zoological analysis of bottom deposits in Baikal. Trudy Baik. Limnol. St. Acad. Sci. USSR, 14: 152-168 . *
Weinberg, E. et al 1999. Spicule Analysis and the prospects of its use for studying the Baikal bottom sediments. Russian Geology and Geophysics 40/8: 1238-1241.
*published in russian

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