Morphologie, Ökologie und Zonierung von Korallenriffen bei Aqaba, (Golf von Aqaba,Rotes Meer)

The coral reefs of the Gulf of Aqaba are among the most northern ones of the world. This study, the first concerning the east coast of this topographically and hydrographically peculiar sea, considers relationships of biophysiographical and structural reef zones to fundamental abiotic environmental factors. An introduction to paleogeography, geology, petrography, topography, climate and hydrography is followed by terminological definitions used to describe the different reef areas. The investigations were carried out on two transects crossing fringing reefs of different shape. Each transect was 20 m wide and run from the shore over nearly 200 m to the fore reef in about 30 m depth. One reef, a “coastal-fringing reef”, represents an unaltered straight reef flat from shore to the reef edge 60 m away; two large pinnacles reach the surface some 125 m off the shore. The other reef, a “lagoon-fringing reef”, is divided into a 100 m wide lagoon of 0.5–2.3 m depth and a reef crest separated from the former by a rear reef. The reef platform of the lagoon-fringing reef is cut by a system of channels and tunnels; the reef edge is about 135 m off shore. Such water depth, substrate, temperature, illumination and water movement were recorded, about 200 common or dominant species (plants and animals) were collected, their distribution plotted and, together with other data and structural items, charted. Indicator species characterize the biophysiographical zones. Their variation as well as that of the structural and substrate zones depend on different zones of water movement. This basic factor also controls other ecological parameters such as food and oxygen supply as well as temperature and salinity gradients between fore reef and shore. From this point of view the ecological requirements of some indicator and other species and conversely the ecological settings of different reef areas are discussed. The different shapes of both reefs are explained on the basis of a “reef development cycle” — a hypothesis applicable to fringing reefs at unchanging sea level and based on the fact that only a small surf-influenced area of “living reef” is able to compensate for reef destruction: While a young coastal fringing reef is growing outwards, its back reef is gradually altered to a reef lagoon by erosion. After stillstand of seaward expansion the reef crest, too, is cut by a channel system eroded by rip currents. This stage is represented by the lagoon-fringing reef. Isolated pinnacles remain as remnants of the former reef crest; young coastal-fringing reefs develop from the shore. This stage is examplified by the first reef studied. Extension, growth intensity, dominant frame building corals, and the number of species of the Aqaba reefs are compared with those of Eilat and with reefs of the middle Red Sea, South India, Southwest-Pacific and Jamaica.     

Quantitative Analyse von Korallengemeinschaften des Sanganeb-Atolls (mittleres Rotes Meer). II. Vergleich mit einem Riffareal bei Aqaba (nördliches Rotes Meer) am Nordrande des indopazifischen Riffgürtels

Quantitative studies of coral communities in the central and northern Red Sea were designed for comparison of the community structure in both areas. The central Red Sea provides reef-building Scleractinia and reef-inhabiting Alcyonaria with optimal temperature conditions, whereas the north tip of the Gulf of Aqaba (29°30 N) represents the northernmost outpost of coral reefs in the Indian Ocean. It is generally assumed that coral diversity decreases towards the margins of the global reef-belt. In the Red Sea, generic diversity of hermatypic Scleractinia slightly decreases from the central to the northern part (51 : 48 genera); but cnidarian species abundance (species number per 25 m² area) was found to increase from 62 to 98 species and the Shannon-Wiener diversity index increased from 2.58 to 3.67 with regard to colony number. The mean colony size was 189 cm² at Sanganeb-Atoll, but only 52 cm² at Aqaba. The mean numbers of colonies were inversely related: 662 per 25 m² at Sanganeb-Atoll and 2028 at Aqaba. Uninhabited parts of the studied areas amounted to 47 % at Sanganeb-Atoll and to 56 % at Aqaba. The community structure of the studied areas indicates that occasional perturbations prevent the progress of the community towards a low-diversity equilibrium state. Since severe hydrodynamic damage is extremely rare in 10 m depth, major disturbances may occur by sedimentation, by the interference of grazers (e. g.Diadema setosum) and due to overgrowth by space-competitors (mainly soft corals). These events are to be regarded as throwbacks in the process of monopolization of the area by well adapted species. Recovery from such perturbations (i.e. recolonization of dead areas) obviously takes place at different velocities in the northern and central Red Sea, for the mean water temperature at Aqaba is 5 °C lower than in the central Red Sea. Hence the process of taking over a given space by a few species proceeds further in the central Red Sea than at its northern end. The increase in diversity per area towards high latitudes is comparable to that with depth. It is concluded from the great number of species at Aqaba that these reefs mark the northernmost outpost of the Indian Ocean only geographically but not ecophysiologically; they would occur at even higher latitudes, if the Gulf of Aqaba extended farther north.     

Zur kenntnis des verhaltens und der ökologie von fischen an korallenriffen bei ghardaqa (Rotes Meer)

Ohne ZusammenfassungHerrn Prof. Dr. Ferdinand Pax zum 75. Geburtstag gewidmet.     

Quantitative Analyse von Korallengemeinschaften des Sanganeb-Atolls (mittleres Rotes Meer). I. Die Besiedlungsstruktur hydrodynamisch unterschiedlich exponierter Außen- und Innenriffe

The Sanganeb-Atoll off Port Sudan is an elongate annular reef which rests on a probably raised block in the fracture zone along the Red Sea-graben. Its gross morphology was most likely formed by subaerial erosion during low sealevel conditions. Features of its topography and hydrography are described. The prevailing wind waves are from NE, Hence, the outer and inner reef slopes are exposed to different hydrodynamic conditions. The sessile benthos was analysed using the quadrat method. Four test quadrats (5×5 m each) were selected on the outer and inner slopes at a depth of 10 m along a SSW-NNE transect across the atoll. Cnidaria were by far the most dominating group; coralline algae, Porifera, Bryozoa and Ascidia, however, counted for just under 3 % living cover. Light and temperature intensities did not differ significantly at the sites studied; water movement, however, decreased in the following order: TQ IV (outer NE side of the reef ring) was exposed to strong swell and surf; TQ II (inner side of the SW-ring) was met by a strong longreef current; TQ I was situated on the outer lee of the SW-atoll ring and TQ III in the inner lee of the NE-side. This hydrodynamic gradient correlates with the composition of the coral communities from predominantly branching Scleractinia (staghorn-like and otherAcropora species andPocillopora) in TQ IV, through aLobophyllia, Porites andXenia-dominated community in TQ II, and a mixed community with an increasing percentage of xeniid and alcyoniid soft corals in TQ I, to a community in TQ III which is dominated by the soft coralsSinularia andDendronephthya. The cnidarian cover ranged between 42.4 and 56.6 % whereby the two exposed test quadrats had a higher living coverage than the protected ones. In total, 2649 colonies comprising 124 species of stony, soft and hydrocorals were recorded by an elaborate method of accurate in-situ mapping. The 90 scleractinian species found include 3 species new to the Red Sea and 11 hitherto unknown species from its central part. Only 7 cnidarian species covered large areas, forming aXenia macrospiculata-zone in TQ I, a Lobophyllia corymbosa-zone in TQ II, aSinularia-Dendronephthya-zone in TQ III and anAcropora-Pocillopora verrucosa-zone in TQ IV. Hydrodynamic exposition and ratio of genus abundanceAcropora: Montipora are closely correlated: on the windward side (TQ IV) it is 943:4, but on the leeward side (TQ I) 18:208. Apart from the taxonomic and quantitative distribution of species and colonies, types of growth form and categories of the dead substrate are given. Since soft corals do not contribute to the reef framework, the distribution of Scleractinia and Alcyonaria indicates that at Sanganeb-Atoll reef substance is mainly generated on the windward side.     

Zur Analyse von Gleichgewichtsstörungen bei Naturfunden

Ohne Zusammenfassung     

Die lichtabhängige Besiedlung von Hafenstützpfeilern durch sessile Tiere und Algen aus dem Korallenriff bei Eilat (Rotes Meer)

The influence of light on coral reef communities has been studied in the merchant harbour of Eilat (Red Sea), where other parameters of the local ecosystem remain relatively constant. The harbour pier is supported over a length of about 550 m by eight rows of concrete pillars. Water current is parallel to the pillar rows. Benthic animals and algae settle on the pillars, between the sun-exposed first and the extremely shadowy eighth row, according to the light gradient (about 13 – 0.1% of the light intensity above the surface). The observations were carried out from January, 1970 to March, 1971. In the most common species (28 animals and five algae), four settlement zones can be distinguished: (a) “bright zone” (13 – 3% of the light intensity measured above the water surface) withTridacna maxima, T. squamosa andPadina pavonia and some stone corals as indicators; (b) “dim-light zone, bright” (3 – 1%) withSiphonochalina siphonella andDendronephthya species as indicators; (c) “dim-light zone, dark” (1 – 0.4%) withAcabaria biserialis andClathraria rubrinodis as indicators; (d) “dark zone” (0.4 – 0.1%) with violetLithothamnion andLithophyllum species as indicators. The distribution of animals in the horizontal light gradient (rows 1–8) corresponds to that in the vertical light gradient in coral reefs; this has been verified by SCUBA diving to 40 m depth near Eilat, Dahab, and Sharm el Sheikh on the Sinai coast, and Aqaba on the Jordanian coast of the Gulf. Light intensity is the dominant ecological factor which affects the distribution of the majority of species in the reef.     

Morphologische und ökologische Anpassungen vonAcabaria-Arten (Octocorallia) im Roten Meer an verschiedene Formen der Wasserbewegung

Zusammenfassung 1. Da standort- und formbestimmende Einflüsse ökologischer Faktoren auf Organismen im ausgebildeten Korallenriff meist nur sehr unzulänglich bestimmbar sind, wurde die Wirkung verschiedener physikalischer Einflüsse an speziell hierfür geeigneten Kunstbauten bei Eilat (Israel) im Golf von Aqaba untersucht. So wurde der Einfluß der Wasserbewegung an Gorgonarien studiert, die auf den Stützpfeilern im Handelshafen von Eilat siedelten.2. Die beiden ArtenAcabaria pulchra undA. biserialis kommen im gleichen Helligkeitsbereich (2–0,5% der über der freien Wasserfläche gemessenen Beleuchtungsstärke) vor.A. pulchra ist auf den Turbulenzbereich der anlaufenden Wellen in den obersten 2 m Wassertiefe beschränkt. Die Strömungsverhältnisse sind hier durch unterschiedlich gerichtete Wasserbewegung und ständig wechselnden Strömungsdruck charakterisiert. Dagegen kommtA. biserialis im Bereich langsamer bis mäßig starker (3–12 cm/sec), vor allem aber stets gleichgerichteter Strömung vor. Diese Verhältnisse waren im Bereich der Hafenpfeiler in einer Tiefe von ca. 2–6 m gegeben.3. Bei Vergleichsbeobachtungen an verschiedenen natürlichen Riffen des Golfs von Aqaba fand sichA. pulchra unter den typischen Bewohnern des Grotten- und Höhlensytems der Riffkante.A. biserialis wurde fast ausschließlich im Dämmerbereich unter 7 m Tiefe im Bereich der Rifflängsströmung gefunden. Durch die ständig anund ablaufenden Brandungswellen ist dieser Bereich fortwährend wechselnden Strömungsverhältnissen ausgesetzt.4. Die Kolonieform scheint arttypisch den verschiedenen Strömungsbedingungen zu entsprechen:A. pulchra wächst sparrig strauchförmig in alle Richtungen. Die Kolonien bleiben niedrig (6 cm) und werden auch bei starkem Strömungsdruck nicht abgebogen. Die Polypen sind gleichmäßig rings um die Zweige angeordnet.A. biserialis entwickelt sich flächig und dabei quer zur vorherrschenden Strömmungsrichtung, um einen maximalen Filtriereffekt zu erzielen. Die fächerartigen Kolonien erreichen eine Höhe von 30 cm. Die Polypen sind zweireihig längs der Seiten der Zweige angeordnet.5.Acabaria pulchra ist neben der habituell gleich erscheinenden, aber seltenenA. erythraea die einzige Gorgonarie im Roten Meer, die in den Bereich der Riffkante mit seinen wechselnden Strömungsrichtungen und -drücken vorgedrungen ist. Als Anpassungen an die Verhältnisse werden der niedrige Wuchs, die allseitig sparrig verzweigte Form und die gleichmäßige Verteilung der Polypen auf den Zweigen angesehen.

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Morphological and ecological adaptations ofAcabaria species (Octocorallia) to different kinds of water movement in the Red Sea

The influence of turbulent current in comparison to regularly unidimensionally flowing current on the gorgoniansAcabaria pulchra, A. erythraea andA. biserialis has been studied in the merchant harbour of Eilat. Their distribution on the concrete pillars supporting the harbour pier was restricted to shadow areas (2–0.5% of the illumination above the free surface). Only in the surf-influenced surface layer with oscillating and pendular currents of changing intensity and direction (down to 2 m),A. pulchra and the very similar but rare speciesA. erythraea were found. Corresponding to these findings,A. pulchra could be observed in the natural reef only in the dark channels and crevices of the reef edge where currents are irregular according to the varying surf intensity. In contrast,A. biserialis settled on harbour pillars below theA. pulchra region in a zone of a regularly unidimensionally flowing long shore current. The rigid colonies ofA. pulchra are small (up to 6 cm high) and thus capable of resisting surf pressure. They are branched in all directions; the polyps are extended on all sides of the branches.A. biserialis reached a hight of 20 cm at the harbour pillars and 30 cm at the slope base of various reefs. Colonies were always two-dimensionally branched. Fans grew from the lateral sides of the harbour pillars into the prevailing long shore current. Corresponding conditions were found on the reef. Perpendicularly positioned to the current, they achieve a maximum filter effect. The polyps ofA. biserialis are situated in two lateral rows along the branches. The different growth forms ofA. pulchra undA. biserialis seem to be species specific. Both species exclude themselves in their distributional patterns, depending on water movement:A. pulchra (together withA. erythraea) is the single gorgonian in the Red Sea, settling on the reef edge and outer flat exposed to surf influence;A. biserialis grows in deeper water, like a typical sea fan, in the zone of unidimensionally flowing long reef current.

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Mit Unterstützung der Deutschen Forschungsgemeinschaft.     

Haltung und Zucht von Basstölpeln Morus bassanus (Linnaeus, 1758) im Zoo am Meer Bremerhaven

Already at the opening of the Zoo am Meer in 1928 the Northern Gannets (Morus bassanus), whose main range is located off the east coast of Scotland, were part of the animal collection of the small zoo at the Weser river in Bremerhaven. The first successful breeding at the Zoo am Meer and thus also the first time in captivity at all, succeeded in 1988. Presumably the breeding was only successful because of the exceeding of a critical group size that allows certain group dynamic behaviours.After a complete renovation of the Zoo am Meer in 2004, a new phase of breeding with 16 animals began. Already in 2005 there was the first offspring and since then a total of 30 chicks hatched. Consistently it happens that animals that shelter their chicks are distracted by one bird and other birds steal and eat the chick. Plaster eggs for couples without oviposition or the removal of individuals provide relief during this critical period.     

Physiologisch-ökologische Experimente anLigia oceanica (Isopoda)

Zusammenfassung Die Salinit?t im Substrat, die Art des Substrates und die Art der Nahrung bilden fürLigia oceanica drei Faktorenkomplexe, die untereinander partiell kompensierbar sind : zwei von ihnen müssen stets im Optimalbereich liegen, um ein überleben adulter Ligien zu erm?glichen. Der Optimalbereich ist durch eine Salinit?t zwischen 8 und 40‰, durch Sand oder Stein als Substrat und durch Braunalgen als Nahrung gekennzeichnet. Hohe Temperaturen setzen die Salinit?tstoleranz vonLigia oceanica herab. Junge Tiere rind empfindlicher als alte. H?utungen und Gravidit?t setzen bei alten Tieren die Resistenz gegenüber extremen Umweltfaktoren herab. Herzschlag und Sauerstoffverbrauch lassen keine Rückschlüsse auf die Qualit?t der gebotenen Umweltbedingungen zu.

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Summary The salinity of the substratum, the nature of the substratum and the food are three complex factors whose effects onLigia oceanica can compensate one another to a certain extent: Two of them have to be in an optimal range to guarantee the survival of adultLigiae. The optimal has a salinity from 8 to 40‰, a sandy or stony substratum and brown algae. High temperatures affect the salinity-tolerance ofLigia. Young animals are more delicate than adults. The resistancy of adults is weakened by gravity and moulting. The frequency of the heart beat and the oxygen consumption give no indication of the quality of the ecological factors.

     

Ein Fall der abhängigen Entwicklung von Linsenfasern bei völligem Mangel eines Augenbechers bei Triton

Ohne Zusammenfassung     

Vergrösserung von Aortenepithelzellen,gefunden bei hochgradiger Sklerose

Ohne Zusammenfassung     

Gliridae (Rodentia,Mammalia) des Eichkogels bei Mödling (Niederösterreich)

Five dormice species belonging to five genera have been recognized at Eichkogel:Vasseuromys thenii nov. spec., Muscatdinus pliocaenicus Kowalski 1963,Myomimus dehmi (De Bruijn 1966),Glirulus lissiensis HuguEnEy & Mein 1965 and a glirid gen. et spec, indet. Petauristinae, Eomyidae and most of the Gliridae representing almost half to the Eichkogel rodent species are thought to have inhabited moist woodlands.     

Die Beschreibung von Hörversuchen anhand eines einfachen,systemtheoretischen Modells

Summary It is shown that sets of quantities that are investigated in hearing-experiments, namely sounds and sound-sensations, can be referred to as input- and output-sets of conciously percepting systems. A simple system-theoretic model of a conciously percepting system is given, the set-functions between input and outputs are derived. The basic steps to measure these set-functions and to estimate accompaning possible errors are discussed. The results can be generalized on perceptional experiments concerning other senses than hearing.

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Aus einer am IENT Aachen angefertigten Dissertation.     

Nahrungsökologische Untersuchungen an Mantelmöwen(Larus marinus) auf Helgoland

This paper is based on observations and the analysis of 54 stomach contents of great black-backed gulls obtained from the island of Helgoland (North Sea) in 1971 and 1972. It deals with the following problems: How large is the share of food taken from the human area in progressing synanthropy of the great black-backed gull? Does this gull have any negative effect on the colony of guillemots(Uria aalge albionis) on Helgoland? Do great black-backed gulls bring further danger (in addition to weather, etc.) for smaller birds migrating over or resting on Helgoland in spring and autumn? 73.5% of the food taken up is of human origin, only 26.5% is considered to be natural food (Crustacea, Mollusca, Insecta). 36 (66.7%) stomachs contained remainders of fish, mainly cod(Gadus morhua), whiting(Merlangius merlangus) and poor cod(Trisopterus minutus). Together with herring gulls(Larus argentatus), great black-backed gulls often swoop down on fishing guillemots to recover the just captured fish from them. They also attack homing guillemots in the range of their breeding rocks. Only in one case the remainders of a smaller bird were found, but presumably a greater number of smaller birds is killed by great gulls.     

Beiträge zur Analyse der Wachstumsförderungen bei Einwirkung von Hemmstoffen auf Mikroorganismen im Diffusionstest

Zusammenfassung An der Förderung des Mikroorganismenwachstums am Rande der Hemmzone des Diffusionstestes können mehrere Faktoren beteiligt sein.Für Förderungen, die am Rande von Hemmzonen ohne Einwirkung von Hemmstoffen demonstriert werden können, wurde zur Unterscheidung vom Konzentrationseffekt der Hemmstoffe der Begriff Randwachstumseffekt geprägt und hierbei zwischen einem nährstoffbedingten Randwachstumseffekt (Randwachstumseffekt 1. Art) und einem solchen 2. Art unterschieden, der dadurch entsteht, daß autotoxische Hemmstoffe der Testorganismen aus dem Randbereich wegdiffundieren und der Testorganismus dort weniger unter der autotoxischen Wirkung zu leiden hat als in seinem hauptsächlichen Wachstumsbereich. Es kann angenommen werden, daß solche Randwachstumseffekte im Mikroorganismenreich weit verbreitet sind und sicher auch Anlaß waren, daß fälschlich auf Förderwirkungen unterschwelliger Hemmstoffkonzentrationen geschlossen wurde.Für Bacillus subtilis als Testorganismus ließ sich auf den Trypsin-Pepton-Agarplatten ein Randwachstumseffekt 2. Art in Höhe von 52% Wachstumssteigerung nachweisen. Bei Colletotrichum atramentarium traten Randwachstumseffekte nicht auf.Die jeweiligen Versuchsbedingungen sind für die Beurteilung des Förderungsphänomens von großer Bedeutung.Die Methoden der qualitativen und quantitativen Analyse der Faktoren, die Förderungswälle im Diffusionstest verursachen können, wurden beschrieben und die Möglichkeiten und Grenzen der Förderungs-analyse diskutiert.