Zur Bryozoen-Fauna der deutschen Meeresgebiete und Brackwässer, 1 : neue Funde

In deutschen Meeresgebieten und Brackwässern wurden erstmals nachgewiesen: Crisia aculeata HASSALL (Helgoland, ? "Lister Rhede"), Electra monostachys (BUSK) (Weser-Mündung, N von Wangerooge, Schleswig-Holsteinische Austernbank), Conopeum seurati (CANU) (Nordostseekanal, Kieler Förde), Callopora dumerilii (Aunoum) (Helgoländer Tiefe Rinne). Buskia nitens ALDER wurde in der Kieler Bucht und bei Helgoland gefunden. Aetea truncata (LANDSBOROUGH) wurde erstmals in der Kieler Bucht nachgewiesen. Bei Helgoland wurde eine nicht bestimmte Crisia gefunden. Electra monostachys kann (vermutlich durch saure Sekrete) auf kalkigem Substrat "Spuren" bilden in Form von Verfärbungsflecken oder kleinen länglichen Gruben unter der Mitte der Cystide. The following species have been found for the first time in German marine and brackish waters: Crisia aculeata HASSALL (Helgoland, ? "Lister Rhede"), Electra monostachys (BUSK) (Weser-Mündung, N of Wangerooge, Schleswig-Holsteinische Austernbank), Conopeum seurati (CANU) (Nordostseekanal, Kieler Förde), Callopora dumerilii (Aunoum) (Helgoländer Tiefe Rinne). Buskia nitens ALDER has been found in the Kieler Bucht and around Helgoland. Aetea truncata (LANDSBOROUGH) is new in the Kieler Bucht. An undetermined Crisia has been found near Helgoland. Electra monostachys is able to produce coloured markes and sometimes small excavations (possible by acid secretions) in the carbonate substrate under the cystids

Bryozoen als Holzschädlinge im Brackwasser

In der Oberen Eider bei Rendsburg wurden erstmals folgende Bryozoen-Arten gefunden: Bulbella abscondita BRAEM, Tanganella mülleri (KRAEPELIN), Bowerbankia gracilis LEIDY und Conopeum seurati (CANU). Die letztgenannte Art wurde mit einem Fund im Nordostseekanal 1965 zum ersten Mal in deutschen Gewässern nachgewiesen. Eine minierende Wuchsform (forma perforans) wurde erstmals von Tanganella mülleri in verwittertem Holz in der Oberen Eider gefunden. Bowerbankia gracilis (Vesicularina) bildet Dauerknospen (wie die Arten der Paludicellea, z.B. Bulbella abscondita und Tanganella mülleri), die in die morsche Oberflächenschicht des Holzes eingesenkt werden können. Bulbella abscondita und Tanganella mülleri minieren, indem sich die wachsenden Knospen durch das morsche Holz pressen. Diese Arten haben stellenweise einen deutlichen Anteil an der Entstehung der Verwitterungsrinde an Holz im Brackwasser (und vermutlich auch im Süßwasser). Durch ihre lokal große Siedlungsdichte und durch die anscheinend weite Verbreitung können die minierenden Bryozoen als Schädlinge an Wasserbauten aus Holz auftreten. The following Bryozoan species have been found for the first time in the Obere Eider near Rendsburg: Bulbella abscondita BRAEM, Tanganella mülleri (KRAEPELIN), Bowerbankia gracilis LEIDY, and Conopeum seurati (CANU). The occurence of the latter in German waters was first ascertained by a find in the Nordostseekanal in 1965. A penetrating growth (forma perforans) was found for the first time for Tanganella mülleri in rotten wood in the Obere Eider. Bowerbankia gracilis (Vesicularina) builds lasting buds (as known from the Paludicellea, for example Bulbella abscondita and Tanganella mülleri), which may penetrate the rotten surface layer of the wood. Bulbella abscondita and Tanganella mülleri grow penetrating by pressing the buds through the rotten wood. Sometimes these species no doubt help to decompose the wood in brackish water (and probably also in fresh water). These penetrating Bryozoans, which show a great lokal density and are probably widely distributed, may threaten wood constructions in water

Zur Bryozoen-Fauna der deutschen Meeresgebiete und Brackwässer, 2 : kalkminierende Bryozoen

Immergentia suecica, Terebripora comma und Penetrantia concharum wurden erstmals in deutschen Gewässern in der Tiefen Rinne bei Helgoland gefunden. Diese kalkminierenden Formen sind sehr häufig in Schillbänken im vollmarinen Bereich und scheinen ein bedeutender Faktor bei der Zerstörung und Reminiralisierung von Mollusken-Schalen zu sein. Immergentia suecica, Terebripora comma, and Penetrantia concharum have been found first in German waters in the Tiefe Rinne near Helgoland. These shell penetrating species are very common in shell beds in typical marine waters and seem to be an important factor for destruction and reminiralization of molluscan shells

Preliminary observations on the influences of food and other factors on the growth of Bryozoa

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

The protective reflex of Bowerbankia (Bryozoa) : calibration and use to indicate movements of the medium beneath a capillary surface wave

The protective polypide-withdrawal reflex ofBowerbankia imbricata (Bryozoa, Ctenostomata) was released by controlled oscillations of the medium (water). The range of effective oscillation frequencies extends from 10 to 200 Hz. The displacements at the threshold of the reflex are 120 μm (peak to peak) at 10 Hz, an average of 30 μm in the range 40-80 Hz, and 150 μm at 200 Hz. The thresholds of oscillation velocity remain within the limits of 0.5 to 1.0 cm/s throughout the frequency range 10-110 Hz, which suggests that this parameter is involved in stimulus reception. The "all-or-none reflex movement" of the animal was employed as an indicator of the position of a defined amount of displacement of the medium beneath a capillary surface wave; this result was compared with calculated values

Assessing zoo giraffe survivorship: Methodological aspects, historical improvement and a rapid demographic shift

Giraffe have been kept in zoos for a long time. They have traditionally been considered difficult to maintain due to various husbandry requirements, including their nature as intrinsic browsers. However, zoo animals are expected to achieve higher survivorship than free-ranging conspecifics due to protection against dangers that would be experienced in their natural habitat. Global zoo giraffe data was analysed for historical developments of juvenile and adult survivorship, assessing the data with various demographic measures and comparing it to that of populations from natural habitats. Additionally, zoo population structure was analysed, in particular with respect to two events that occurred in parallel in 2014—a recommendation to restrict the number of new offspring given by the European Endangered Species Programme (EEP) studbook coordinator and the culling of a designated ‘surplus’ giraffe at Copenhagen Zoo that attracted global media attention. Both juvenile and adult giraffe survivorship has increased over time, suggesting advances in giraffe husbandry. For juveniles, this process has been continuous, whereas for adults the major progress has been in the most recent cohort (from 2000 onwards), in parallel with the publication of various husbandry guidelines. Zoo giraffe survivorship is now generally above that observed in natural habitats. Simple survivorship analyses appear suitable to describe these developments. Since 2014, the global giraffe population has undergone a rapid demographic shift from a growing to an ageing population, indicating a drastic limitation of reproduction rather than a system where reproduction is allowed and selected animals are killed (and possibly fed to carnivores). Thus, giraffe are both a showcase example for the historical progress made in zoo animal husbandry due to efforts of the zoo community and serve as an example to discuss implications of different methods of zoo population management