ALBERT

Description: The problems of reproduction of Octopus vulgaris and the seasonal distribution in the sea of planctonic larvae, benthonic juveniles and adults are discussed. The influence of environmental factors on growth is shown by experimental studies in the laboratory, and the difficulties of interpreting field data are emphazised.

Description: Mineral resources on and beneath the seafloor are briefly reviewed and the present and future economic value of specific mineral resources is discussed. The results obtained from the cruises of the German research vessel "Valdivia" during its first three years of operation are presented.

Description: Aus einer wäßrigen Lösung des Crustaceenäautungshormons Ecdysteron wurden Bakterien in Reinkultur isoliert, die das Hormon abzubauen vermögen. Die mögliche Bedeutung der bakteriellen Inaktivierung des Ecdysterons wird diskutiert. A bacterium which is able to degrade the crustacean malting hormone ecdysterone was isolated from an aqueous solution of the hormone. The possible significance of this inactivation by bacteria is discussed.

Description: Tauchuntersuchungen ermöglichten erste quantitative Angaben über das Vorkommen der Bohrmuschelarten Barnea candida und Zirfaea crispata in der Kieler Bucht. Die Muscheln bewohnen in hoher Siedlungsdichte Geschiebemergelflecken zwischen 2 und 13 m Wassertiefe. Ihre Bedeutung für die Auflockerung des Substrats, das dadurch auch von anderen Benthosformen besiedelt werden kann, ist beträchtlich. Diving investigations have provided first quantitative data on the occurence of boring clams (Barnea candida and Zirfaea crispata) in Kiel Bay. In a zone between 2 and 13 metres of water depth, the clams live in patches of till in large numbers. They have a considerable importance for eroding the substratum, which thus can be inhabited by other benthic species as well.

Description: Fluctuations of horizontal and vertical wind speed components and of air temperature have been measured on a mast in the Baltic Sea. Preliminary results of computed stress and sensible heat flux and their parametrisation with wind speed and air-sea temperature difference are given. Compared with the results of other authors, the present data show the following features: 1. The drag coefficient increases strongly with increasing wind speed. 2. The heat transfer coefficient seems to be smaller under stable stratification than under neutral or unstable conditions.

Description: The thermocline model suggested by ERTEL (1953) is used to describe thin surface layers that had been observed in the Western Baltic. The layers have typical vertical scales of a few decimeters, and their temperature exceeds the temperature of the underlying water by a few tenth °C. Advection is taken into account by means of a source function (including heat sources and sinks). The special case of the mixing coefficient of heat sinks and sources being equal to the coefficient of turbulent heat conduction can be used here if the coefficients are close to the molecular coefficient of heat conduction (approx. 10-3cm 2s-1). The results show that this special case of the model is applicable here. Using the above assumption the vertical temperature distribution during the heating period can be well approximated by using coefficients (10 to 40 10-3cm2s-l) which are sufficiently close to the molecular value.

Description: Es wird eine Methode zur Bestimmung des Kaloriengehaltes von partikularer Substanz aus Schöpfer- und Sinkstoffproben beschrieben. Die Proben werden auf Glasfaserfilter (Whatman GF/C, 2,25 cm Durchmesser) oder Membranfilter (Sartorius, Typ SM 1130, 2,5 cm Durchmesser) filtriert. Die Glasfaserfilter mit dem Filterrückstand werden nach Zugabe von Benzoesäure, die in Äthylalkohol gelöst ist, getrocknet und in einem Phillipson-Mikrokalorimeter verbrannt. Bei der Verbrennung der Membranfilter entfällt die Zugabe von Benzoesäure, da die Filter aus explosivem Cellulosenitrat bestehen. Sie können direkt nach der Trocknung verbrannt werden. Der methodische Fehler liegt bei der Verwendung von Glasfaserfiltern bei 27,1% und bei der Verwendung von Membranfiltern bei 9,6%. Als optimal erwies sich die Verwendung von Membranfiltern der PorengroBe 0,8 µ und die zweimalige Spülung des angereicherten Sestons auf dem Filter mit 2 bis 5 ml destilliertem Wasser. Die Glasfaser- und die Membranfilter weisen keinen signifikanten Unterschied in Bezug auf den Kaloriengehalt des abfiltrierten Sestons auf. In Bezug auf den Sestongehalt (als Trockengewicht) zeigt der Glasfaserfilter eine signifikant höhere Retention gegenüber dem Membranfilter (p1 〈 2% und p2 〈 0,1%). Es ergab sich ein signifikanter Unterschied (p 〈 0,2% in Bezug auf den Seston- und p 〈 0,1 % in Bezug auf den Kaloriengehalt) in der Retention der Filter bezogen auf 1 l Wasser bei der Filtration unterschiedlicher Wassermengen (1 l und 2 l). Aus diesem Grunde sollte immer die gleiche Menge Wasser zur Filtration verwendet werden. Der kalorische Aspekt der Phytoplanktonblüte im Frühjahr 1972 vor Boknis Eck wird dargestellt und diskutiert. Der Kaloriengehalt einer Phytoplanktonpopulation kann als Index für deren physiologischen Zustand angesehen werden.

Description: Different food species cause modifications in the growth forms of bryozoan species. Under cultivation conditions a "stolonization of zooids" is possible in Bowerbankia spp. In some species, e.g. Conopeum seurati and Alcyonidium spp., the numbers of tentacles are influenced by external and physiological conditions. Observations on the brackish water Membraniporid Conopeum seurati are summarized, which revealed that maturity and growth of the erect form are effected by a complex of interdependent factors (colony size, food, temperature, salinity). It is stressed that greater attentions should br paid to the ecologial conditions by taxononoists and systernatists. Numerical inquiries and statistical comparisons which ignore the influences of external factors on the growht forms are questionable. Cultivated Bryozoa may develop forms which under natural conditions will not normally be realized, but which may be of systematic importance. A new cultivation apparatus for long term rearing of sessile plankton feeders has been developed. The experimental vessel of the apparatus has a U-bottom of perspex to sustain a vertical water rotation. The water movement is produced by water in a container vessel, raised above the level in the experimental vessel by an improved type of a bubble-pump. The experimental animals can be observed with a stereo-microscope or with a photo-apparatus without removal from the experimental vessel.

Description: This work is based on 63 samples obtained by Beyer's 50 cm epibenthic closing net and 43 vertical hauls with a 70 cm Hensen-net from December 1969, and March, June and November 1970. The depth in the sampling locality, Vejsnäs Rinne, varied between 28 and 32 meters. Only abundant and particularly interesting species and animal groups have been treated here. Seasonal variations were studied in the cumacean Diastylis rathkei, some mysids, the euphausid Thysanoessa raschii, the decapod Crangon crangon, the chaetognath Sagitta elegans and in some fishes. During winter there are, relatively, a higher number of species (including some rare ones), as well as of individuals. This may partly be ascribed to a stronger inflow of water from the Kattegat in winter, and partly to seasonal horizontal migrations in the animals. It is furthermore apparent that by the present sampling method a larger fraction of the more vagile near-bottom fauna is collected than by more conventional sampling techniques. The diurnal variations in the hyperbenthos were studied in benthic as well as some pelagic groups of animals. Based on the results, it is possible to recognise at least three main patterns of vertical migrations in the hyperbenthos: A. The relatively few pelagic animals found stay just above the bottom during the day. They leavethe region sampled by the epibenthic closing net (i.e. from the bottom to about 80 cm above it) about sunset and stay away until the next morning when they reappear at this level. B. Some of the benthic animals at certain seasons or developmental stages are sparsely represented in the epibenthic closing net samples during day. The catches are increased at dusk, but decrease again later in the evening. In the morning the animals appear once more in the hyperbenthos, only to disappear again after sunrise. The reduced number collected around midnight is either due to midnight sinking, i.e. the animals burrow in the sediment and thus avoid the epibenthic net, or the animals ascend above the level sampled by the net. This last pattern is particularly found in juveniles and in gravid females. C. The majority of the migrating benthic species seem to come sufficiently far off the bottom to be caught in higher numbers in the epibenthic closing net during the dark hours. They are often considerably less numerous throughout the day. The value to an animal of performing diurnal vertical migration has been briefly discussed. It seems possible that some of the more important demersal fishes in the area are able to exploit the migrating animals as food, particularly at dawn and dusk.