ALBERT

Description: Burrowing activities of the only European fiddler crab, Uca tangeri, and its resulting influence on biotope in mudflats were investigated during 1989-1990 at Ria Formosa, Portugal. Individuals use the same burrow for ca 1 wk, then occupy another or dig a new one. Overall a burrow is inhabited for ca 3 mo by several individuals before it is abandoned. Vacated burrows decay within 2 to 3 wk. Burrow size and number vary with the season. Burrow density was highest in spring and early summer with ca 17 burrows m-2, and then decreased. Deepest burrows (up to 90 cm long) were found in winter, the shallowest (up to 40 cm long) in summer. Volume of the sediment moved by U. tangen varied monthly between 3000 and 6000 cm3 per m2 of mudflat. Water is only found in the lower third of the burrow. Burrow water contains less oxygen and more nitrate than the surrounding water of the Ria Formosa.

Description: Respiration and activity of eelpouts Zoarces viviparus L. were measured in an underwater respiration chamber in Kiel Bay (Germany) under short-term hypoxia. Respiration and swimming activity both declined almost continuously with decreasing oxygen saturation...

Description: Methane seeps in shallow waters in the northern Kattegat off the Danish coast form spectacular submarine landscapes - the 'bubbling reefs' - due to carbonate-cemented sandstone structures which are colonized by brightly coloured animals and plants. These structures may be 100 m2 in area and consist of pavements, complex formations of overlying slab-type layers, and pillars up to 4 m high. The carbonate cement (high-magnesium calcite, dolomite or aragonite) is 13C-depleted, indicating that it originated as a result of microbial methane oxidation. It is believed that the cementation occurred in the subsurface and that the rocks were exposed by subsequent erosion of the surrounding unconsolidated sediment. The formations are interspersed with gas vents that intermittently release gas, primarily methane, at up to 25 1 h-' The methane most likely originated from the microbial decomposition of plant material eposited during the Eemian and early Weichselian periods, i.e. l00 000 to 125 000 years B.P. Aerobic methane oxidation in the sediment was restricted Lo the upper 4 cm in muddy sand and to the upper 13 cm In coarse sand. Maximum aerobic methane oxidation rates ranged from 4.8 to 45.6 pm01 dm-3 d". The rock surfaces and epifauna around the seeps were also sites of methane-oxidizing activity. Integrated sulphate reduction rates for the upper 10 cm of muddy sand gave 4.2 to 26.6 mm01 m-2 d-' These rates are higher than those previously reported from similar water depths in the Kattegat but did not relate to the sediment methane content. Since gas venting occurs over several km2 of the sea floor in the Kattegat it is likely to make a significant local contribution to the cycling of elements in the sediment and the water column. The rocks support a diverse ecosystem ranging from bacteria to macroalgae and anthozoans. Many animals live within the rocks in holes bored by sponges, polychaetes and bivalves. Stable carbon isotope composition (6'") of tissues of invertebrates from the rocks were in the range -17 to -24 'A, indicating that methane-derived carbon makes little direct contribution to their nutrition. Within the sediments surrounding the seeps there is a poor metazoan fauna, in terms of abundance, diversity and biomass. This may be a result of toxicity due to hydrogen sulphide input from the gas.

Description: During the Bremerhaven Workshop in the southern North Sea, REMOTS sediment profile lmages (SPI) were recorded in order to supplement the benthic component of the workshop and other environmentally relevant parameters investigated along a spatial gradient at an abandoned exploratory drilling site off the Dutch coast. The sampling stations were in accordance with the other studies, but due to bad weather conditions only a small proportion of the intended samples were taken. The profile data were supplemented by video recordings of the sediment surface features taken on a second cruise. The results presented here have important implications for the interpretation of other benthic and sediment samples, and may help to interpret some enigmat~cw orkshop data.

Description: Plgments are frequently used as biomarkers to study the fate of primary producers in the food web. We evaluated the effectiveness of pigment analysis in the giant aquatic isopod Saduna entomon, an important link in the food chain of the Baltic Sea. Specimens were collected on a transect across Puck Bay (Gulf of Gdansk, Poland) at stations comprising different sedimentary conditions and varying supply of micro- and macroalgal material. In laboratory experiments S. entomon was fed different kinds of prey. Different marker coinbinations were found in the intestlnal tissue, resulting from predation on herbivorous and carnivorous species. Analyses of field samples revealed that S. entomon, living in the sedlment surface, ingests freshly sedimented phytoplankton as well as plant detritus ß-carotene and the xanthophyll echinenone were found in the carapax and gonads, supporting the view that these substances are assimilated and servve as antioxidant protection of lipids and other macromolecules.

Description: The individual marking of flying and flightless birds has a long history in ornithology. It is the only technique which is cheap, simple and effective, yielding results on bird migration, age-specific annual survival and recruitment. Consequently, hundreds of thousands of birds are annually ringed worldwide. Unfortunately, researchers all too often tend to neglect problems associated with rings and tags. In Antarctic penguins, flipper bands have been used extensively by a variety of nations, and banding is an integral part of the Council for the Conservation of Antarctic Marine Living Resources' (CCAMLR) monitoring programme (Standard method A4). This programme suggests that mortality in penguins wearing bands can be attributed to either (a) prey species availability, (b) predation, (c) weather conditions or (d) other. In this paper, we have attempted to quantify energetic costs associated with wearing a flipper band. For that purpose, freshly caught Adelie penguins (n = 7) were introduced, in Antarctica, into a 21 m long still-water tunnel, where their behaviour and energy consumption were determined via observation and gas respirometry. Birds were either immediately marked with a flipper band and tested in the tunnel for ca 2 h, and then taken out and tested again after removal of the band, or vice-versa. Flipper bands significantly (ANOVA, p = 0.006) increased the power input of Adelie penguins during swimming by 24 % over the speed range of 1.4 to 2.2 m S-', from 17 W kg-' to 21.1 W kg-' (n = 115 and 157 measurements, respectively). The implications of banding on foraging performance and sunival of penguins are discussed. Implantable passive transponders could help overcome such problems.

Description: The quality of the food, especially origin and size, of the only European fiddler crab, Uca tangeri (Eydoux, 1835), was studied over a 2 yr period. In experiments with fluorescent microparticles, all particles smaller than 250 pm were ingested regardless of thelr chemical composition. Comparisons of sediment, feeding pellets and faeces showed that U. tangeri feeds primarily on microalgae which are completely extracted from the sediment. It also consumes vascular macrophytes (Arthrocnemum spp.), macroalgae, detritus and fish carcasses.