VOLKER
RUDOLF from the Department of Animal Ecology and Tropical Biology at the
University of Wuerzburg in Germany, studies the ecology, the reproductive mode
and the larval biology of the frog species Phrynobatrachus guineensis (Anura,
Ranidae). This species was first described by GUIBE & LAMOTTE 1961 from
Mont Tonkoui, Ivory Coast, but the reproductive mode and the tadpoles remained
unknown, until in 1998 both were discovered in Tai National Park. Phrynobatrachus
guineensis is the first species of African ranids known to reproduce in tree-holes.
The work with this species is part of the BIOTA project for West Africa, and
belongs to an amphibian monitoring program led by Dr. M.-O. Roedel. The main
focus of the monitoring programme is to establish amphibians as a bioindicator
system to evaluate the state of West African rain forests in general and that
of TNP in particular.
Most of the 56 recovered species of frogs in TNP live in swampy parts of the
Tai forest because they need open water for their reproduction or larval life.
Many different types of amphibian reproductive modes are known for the species
in the TNP. But just a small minority of specialists is not dependent on ponds
or rivers for their reproduction and larval life. One of them is Phrynobatrachus
guineensis. This small frog uses water accumulations in treeholes, roots or
even snail-shells. They attach small numbers of single eggs above the water
surface to the walls of the holes, where they develop. After four days, the
tadpoles drop into the water and continue their development until they leave
the holes after less than a month as small froglets. Due to this special and
recently unknown reproductive mode, they are not dependent on ponds and rivers.
Therefore this species is of special interest for the biomonitoring program.
In his research about the ecology of this species in the Tai National Forrest,
VOLKER RUDOLF focus on the choice of the sites in which reproduction takes
place, what affects this choice and its effects on the reproduction and larval
life itself. Nothing is known about the factors being important for this choice
and how they affect the larval development and live. The tadpole-densities
in these holes are up to ten times higher than known from other species. What
are the reasons for this high densities and what effects do they have on the
larval live. To answer this questions the methods used in his studies combine
daily monitoring, observation of marked individuals and field- as well as
laboratory-experiments.
This exceptional reproductive mode, which takes place in these microhabitats,
makes this species not only to an interesting species for the biomonitoring
in the TNP. It although offers an excellent model to study an ecological system
and allows to examine density effects in natural and experimental conditions.
Dr. Mark - Olivier Rödel est le coordinateur du projet amphibiens
dans le Parc National de Taï. Son travail adéjà conduit
vers des découvertes des trois nouvelles espèces d'amphibiens,
deux grenouilles et un crapaud. Il est auteur d'une livre scientifique sur
les amphibiens de l'Afrique de l'Ouest. Son travail fait partie du programme
BIOTA.
Trouvez ci - dessous le thème de recherche d'un collaborateur de Dr.
Rödel
