REMOTE SENSING AND GIS-TECHNIQUES FOR THE EVALUATION OF MACROPHYTES IN THE GREIFSWALDER
BODDEN
Kornelia Christke, University of Rostock, Institute of Geodesy and Geoinformatics, Germany
Commission VII, Working group 8
KEY WORDS: Remote Sensing, GIS, Integration, Classification, Change Detection, Underwater Video, Estimation of
Macrophytes
ABSTRACT
There are great demands for information about the distribution of macrophytes in coastal and brackish water areas.
Continuous data of distribution of macrophytes as well as detailed information about the structure of the population is
required. Defects in the marine ecosystem could be detected only with periodical mapping of the macrophytobenthos.
Remote sensing data offer the possibility to observe a large area at the same time and substitute most dives. The aim of
the investigations is to test the suitability of digitized aerial photographs and other multispectral sensor data for the
evaluation and differentiation of the vegetation under water. Beyond that changes of the macrophyte populations within
a short and a long time period will be investigated by multitemporal analysis.
KURZFASSUNG
Es besteht grofser Bedarf an Informationen zur Verbreitung von Makrophyten in Küsten- und Brackwassergebieten.
Dabei werden einerseits fláchendeckende Angaben zur Verbreitung der Makrophyten, andererseits aber auch detail-
lierte Angaben zur Bestandszusammensetzung benótigt. Periodische Bestandsaufnahmen des Makrophytobenthos sind
Voraussetzung für das zeitige Erkennen von Scháden im marinen Ókosystem. Fernerkundungsmaterialien ermóglichen
eine flächendeckende Abbildung der Gewässer zu einem bestimmten Zeitpunkt und ersetzen einen großen Teil der
Taucharbeiten. Ziel der Forschungen ist es, die Eignung von digitalisierten Luftbildern und anderen multispektralen
Sensordaten für die Erfassung und Differenzierung der Unterwasser-Vegetation zu testen. Außerdem sollen die kurz-
und langfristigen Veränderungen des Pflanzenbestandes mittels multitemporaler Analysen untersucht werden.
1. INTRODUCTION benthos admit the conclusion that benthic organisms can
be mapped by digital remote sensing data. Digital proce-
dures of remote sensing are more effective and flexible
than analogous methods and they are more suitable for
continuous and semi-automated processes and for inte-
gration within an information system.
The Greifswalder Bodden is an important brackish water
area in the southern Baltic Sea. It is the buffer zone
between the salty Baltic Sea and the influx of fresh water
from the inland, where intensive exchanging, mixing and
distribution processes take place. The Greifswalder Bod-
den is an important economical factor in the region
because of the herring-fishery. The macrophytes are the
basis for spawning of the fishes and the refuge of young
water animals. The macrophytes are an important ele-
ment in the ecosystem. They take part in the sedimenta- ^ The Greifswalder Bodden is a 51000 ha large, eutrophic
tion, decrease the power of streams, influence thé ^ shallow water area in the north east of Germany and in
chemical properties of the waterbody and indicate thé ^ the south of the island Rügen. The average depth is 5.60
quality of water. In the last years the demand for infor- ^ m ang the maximum depth is 13.30 m. Tidal effect is
mation about the distribution of macrophytes in the Bod- — scarcely noticed. Geomorphology of the bay and the
den area increased. Continuous and quantitative data are ^ physical and chemical properties of the water are very
required about the distribution of macrophytes, the local heterogeneously. Salinity, flow chart, nutrient and sedi-
structure of population and about the quantitative and ^ ment transportation change extremely with the wind
qualitative changes of macrophyte communities over time conditions. All these factors influence plant growth and
to detect trends inside the marine ecosystem. macrophyte communities. Few species of macrophytes
Remote sensing data offer the possibility to observe a (Zostera marina) build up unmixed populations in the bay,
large area at the same time. The most used method to the most species form mixed communities (Cladophora
map or monitor submersed vegetation is the photointer- glomerata, Enteromorpha spec., Polysiphonia nigrescens,
pretation (e.g. Lang, 1969; Remillard, 1992; Ferguson, Furcellaria fastigiata, Potamogeton pectinatus, Fucus
1993). Another method is the combination of photointer- vesiculosus and other). The portions of the species in the
pretation with measurements of photo-density community and their frequencies depend strongly on the
(Tanaka,1988). Siegels investigations (Siegel, 1992) sediment, slope, aspect, light and temperature (Geisel,
about the spectral reflectance of sediments and phyto- 1986). Dependent on the season epiphytes (Ectocarpus
2. STUDY AREA
142
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B7. Vienna 1996
