Scientific research topics 1999

1.) GROWTH OF HERMATYPIC CORALS III: A LONG- TERM SURVEY
Harald Fischer, Birgit Greiner, Michael Zika

ABSTRACT
This project presents the results of the annual growth of reef-building corals in the Gulf of Aqaba, Red Sea, Jordan. The survey was initiated in November 1997 and first results were obtained in November 1998. In 1999 the most obvious results were recorded in branching colonies such as Acropora sp., Stylophora pistillata, and Millepora dichotoma. The investigation of growth and colonisation of corals on artificial substrates was extended and yielded first results.

2.) ASSESSMENT OF CORAL REEF DAMAGE IN AQABA, JORDAN
Stefan Achleitner, Fanni Aspetsberger, Pierre Madl, Daniela Meisel, Sonja Schwent, Maricela Yip

Introduction
The coral disease survey was attempted for the first time in 1999 as part of the Marine Ecology Field Course by the University of Vienna, Institute of Ecology. The main interest was focused on hard corals (scleractinians) because they comprise most of the framework of a living coral reef, and they are home for a great number of marine organisms. Coral mortality in reefs is a well-known and common event. Even the healthiest reefs always contain some dead colonies among the coral aggregation. Although the aragonitic skeletons of hard corals remain intact long after the coral animal has died, they scarcely reveal the cause of their death. Thus, coral mortality is easy to record but difficult to investigate. Despite this complication, some coral degradation can be easily traced and calssified as biological destruction such as predation (e.g. by polychaetes, crustaceans, molluscs, echinderms, fish, etc.). On the other hand, corals can also die from being overgrown by algae, sponges, zoanthids, octocorals, ascidians or simply due to interspecific competition. Recently, coral mortalitiy seems to reveal yet another set of causes which goes beyond those listed above - symptoms of anthropogenic origin. Coral diseases, first reported in 1973, have not yet received the attention of marine biologists that they would deserve. With the onset of global climate change (a factor that should no longer be neglected), however, their frequencies and extent of damage are on the increase. Recent reports regarding diseased corals from around the world have focused on these dramatic events. In order to avoid their continuos spreading and to attempt the conservation of healthy corals for future generations, coral disease monitoring deserves more attention today than in the past.

3.) CHARACTERISATION OF DIFFERENT FISH SPECIES WITH REGARD TO THEIR ASSEMBLAGE, ARRANGEMENT AS WELL AS NORMAL AND DISTURBANCE BEHAVIOUR IN THE GULF OF AQABA/ RED SEA
Alexandra Haselmair, Philipp Steiner, Barbara Trattner, Wolfgang Huber, Martina Kutlaca

ABSTRACT
Red Sea fish species show every type of social behaviour. They live solitary, in pairs in small groups or in huge schools. This study was conducted near Aqaba/Jordan in the gulf of Aqaba by scuba diving. Measured were the species assemblage, the species arrangement above a coral block and the normal and disturbance behaviour around two coral blocks. The observed fish species showed different behaviour, e.g. the very stereotypic behaviour of Pomacentrus trichourus compared to them of Dascyllus trimaculatus (bulk courtship behaviour). For the species assemblage two different types of fish aggregation were picked out: schools of wandering grazer: Heniochus diphreutes, and shools with permanent shelter on the reef; e.g. Chromis viridis, Dascyllus trimaculatus, Pomacentrus trichourus, Pseudanthias squamipinnis. Nummerically, P.squamipinnis dominated around the coral blocks. The assembly of species was identical on Block I and Block II. The distribution also did not differ far between the two blocks. Most fishes had a territory or home range, which they did not leave.

4.) SAND BOTTOM FAUNA IN THE GULF OF AQABA (RED SEA, JORDAN)
Hubert Blatterer, Wolfgang Waitzbauer, Nikolaus Czaszar, Michaela Knosp, Nikolaus Ritter

Introduction
Several trips have been made to the reefs of Aqaba and different habitats were examined by the faculty and students of the University of Vienna. Various biological topics were investigated every year. The sediment fauna around the Royal Diving Center was examined for the first time in 1999. Therefore no records or results were available. Special methods were developed by our team to study this habitat. The most difficult and time-consuming process was the accurate determination of the material. We recorded many difficult-to-determine species due to lack of identification keys for Aqaba.