ALBERT

Description: Distribution and abundance of the horned octopus Eledone cirrhosa in the Tyrrhenian Sea are described on the basis of stratified-random bottom trawl surveys in spring and summer of the years 1985–1987. Specimens were caught between 25 and 630 m depth (higher densities between 50 and 200 m depth); mature males were found to prefer deeper bottoms than mature females. Young specimens occurred in spring samples from the Western Ligurian Sea and in summer samples from the Lower Tyrrhenian Sea, but were scarcely represented in the Higher Tyrrhenian Sea. Thus recruitment seems to be progressively delayed later in the season from north to south. The greatest abundance was recorded in the Higher Tyrrhenian Sea; wide seasonal variations of minimum stock biomass estimates have been observed and total biomass decreased from 1985 to 1987 in the surveyed areas.

Description: An investigation was carried out on the morphology, growth and microstructure of statoliths of 833 specimens of Sthenoteuthis pteropus (Steenstrup) mantle length (ML): 2–548 mm collected in the open waters of the Gulf of Guinea in 1984–1988. Statolith morphology is similar to that of other species of the subfamily Ommastrephinae and is similar to the sibling species S. oulaniensis. Statolith development includes five stages resembling those of Illex illecebrosus and other ommastrephids. Statolith growth is characterized by negative allometry. Increments visible in ground sections of statoliths can be grouped into four main growth zones, differing mainly in colour and increment width. Age and growth rates of S. pteropus were calculated using increment counts. The life span of females of all size groups does not exceed 1 yr, that of males is 1–2 months shorter, probably due to preliminary mating. Instantaneous relative growth rage (G) of paralarvae is high (up to 16% of body weight (BW)). G values for juveniles decline, but remain relatively high (7–8% BW). Juveniles attain 100–110 mm ML by age 100–110 days. G values for adults are the lowest (1.8–2% BW), but daily growth rates reach maximum values (40–70 g per day in large females of 450–500 mm ML). Each ontogenetic phase of S. pteropus corresponds to features of morphology, growth and microstructure of the statolith.

Description: Mean intracellular pH (pHi) and PCO2 (PiCO2) have been analysed based on pH and total CO2 measurements in tissue homogenates. Tissues were sampled from undisturbed worms (Sipunculus nudus), squid (Illex illecebrosus), trout (Salmo gairdneri), toads (Bufo marinus), and rats. Homogenate metabolism was inhibited by the addition of potassium fluoride and nitrilotriacetic acid (NTA). Model calculations revealed that the influence of dilution, medium buffers, and contamination by extracellular fluids was negligible. In white muscle tissue the resulting pHi values were virtually the same as found in studies using DMO (dimethyloxazolidinedione). If large fractions of mitochondria were present (e.g. in heart muscle), DMO derived pHi values were considerably higher, probably representing overestimates. Homogenate derived pHi values are concluded to represent the effective mean pHi by taking into account pH gradients, and the volumes and buffering of cellular compartments. High time resolution and small variability make this method especially useful to assess rapid changes in pHi, e.g. in exercising animals.

Description: The periodicity of deposition of growth increments in the cuttlebone of juvenile Sepia officinalis was investigated under controlled conditions for a short period after hatching (19 days). The slope of time elapsed and increment counts was significantly different from 1 indicating that lamellae are not deposited on a daily basis. The relationship between increment counts and juvenile length was, however, highly significant. Also significant were the relationships between the number of growth increments and shell length and increment counts and cuttlebone area. These data show that the number of growth increments is related primarily to the growth rate of the juvenile rather than to its chronological age. Taking into account these data, the cuttlebone lamellae cannot be used for age determination in the juvenile cuttlefish just after hatching.

Description: The presented data on indirect and direct calorimetry in Halicryptus spinulosus, a species with prominent ecological significance in parts of the Baltic Sea, provide a basis for a better understanding of the metabolic adaptation of these animals to low oxygen availability in their environment. Metabolic rates in H. spinulosus were measured respirometrically as oxygen consumption and calorimetrically as heat dissipation. Oxygen uptake rates are in the range of M O2 = 3.81 ± 1.37 μmol O2·g−1 dry mass·h−1. Upon reimmersion into normoxic seawater after an anoxic incubation of 7 days, the animals exhibit an overshoot of oxygen consumption by a factor of 2.4. It takes at least 2 days for the animals to balance their oxygen consumption to previously measured rates. Direct calorimetry exhibits different strategies of H. spinulosus to cope with declining oxygen and anoxia. During the first 2 transitional days to anoxia in the calorimeter, the animals decreased heat dissipation moderately down to 53.4 and 26%, respectively, of aerobic values. The animals are not necessarily quiescent at the beginning of anoxia, but at the end of the experiments after 14 days metabolic rates have dropped substantially down to ≈2% of normoxic values. These findings are discussed with regard to an effective adaption to frequently changing oxygen regimes in deeper parts of the Baltic Sea.

Description: CO2 partial pressure in surface water was measured in the Northeast Atlantic and in the Hebride Shelf/North Sea area during a cruise with R.V. Poseidon in June 1991. A mean pCO2 of 303 μatm was found in the Atlantic between 50°N and 60°N. For an atmospheric CO2 content of 357.5 ppm(v) this corresponds to a partial pressure difference of −55 μatm. This supports the view that the subarctic Atlantic is a significant sink within the CO2 cycle between the ocean and the atmosphere. A comparison of our measurements with other data reveals that the pCO2 distribution changes significantly during May/June. This explained by seasonal warming, CO2 exchange with the atmosphere and biomass production. The contribution by each of these processes to the seasonal variations is calculated. It was found that during a plankton bloom the production of biomass is the dominating factor and may lower seawater pCO2 by almost 100 μatm. The shelf areas are charactrized by strong pCO2 gradients which are explained by water exchange with the Atlantic, temperature effects and biomass production.

Description: Skin and hair samples of harbour seals (Phoca vitulina) found dead along the west coast of northern Germany in 1988 were analysed for total mercury, cadmium and lead. Cadmium and lead concentrations were below the detection limit in most skin samples. The mercury content of the hair (median: 23.1 μg g−1 wet wt) was several magnitudes higher than the mercury content of the skin (0.27 μg g−1 wet wt). Mercury concentrations in hair samples were significantly higher than lead concentrations (0.54 μg g−1 wet wt), which significantly exceeded cadmium levels (0.09 μg g−1 wet wt). Female seals revealed lower cadmium concentrations in the hair than male seals. Accumulations of metals with age were observed for cadmium and lead in hair samples and for mercury in skin samples of male seals. A connection between metal accumulation and pigmentation or rather moult was clearly recognizable.

Description: The spreading of Mediterranean Water (MW) released through the Straits of Gibraltar is studied with hydrographic data, oxygen, nutrients and for the first time with chlorofluoromethane (CFM, compounds F11 and F12) distributions along seven sections in the Gulf of Cadiz, and with measurements in the Western Alboran Sea and west of the Gulf. The properties of MW entering the Gulf are deduced from CFM-salinity correlations east and west of the Straits as well as from property-depth profiles in the Western Alboran Sea. At the time of the survey, the outflow originated from depths above the salinity maximum of the Intermediate Water in the Alboran Sea. It turned out that the F11/F12 ratio of the outflow is equal to the ratios found in the Atlantic water in the Gulf of Cadiz; thus the ratio carries no time information in the region. A model is developed to describe mixing of the MW undercurrent with overlying North Atlantic Central Water (NACW) from different depths. The contribution of each layer to the mixing is parameterized by a weighting factor, which has to satisfy the balances of potential temperature (θ), CFMs, oxygen and nutrients in the MW undercurrent. It is shown that entrainment of water from shallower depths into the undercurrent is important near the Iberian Continental Shelf. Farther west and south, the undercurrent mainly mixes with water from near the salinity minimum of the NACW. For regions where the undercurrent has left the bottom, additional mixing with North Atlantic Deep Water (NADW) has to be taken into account. The percentage of MW in the undercurrent decreases from 76% hear the Straits to about 34% at 7°30′W for the lower core (MI) and about 22–24% for the upper core (Mu). Assuming an outflow of undiluted MW through the Straits of 1.0 Sv, the transport of the undercurrent can be calculated by determining an average dilution factor for each section. The undercurrent transports 2.0 Sv just west of the Straits and 3.6 Sv leave the Gulf of Cadiz. At 36°N, 9°54′W, a meddy with unusually high temperatures and salinities below 500 m was found, covering the density range for both cores, Mu and Ml. From the θ−S characteristics and the evaluated mixing scheme of the meddy it appears to have formed near 7°W in the Gulf, a region up to now not proposed in the literature, and moved westward without much further mixing.

Description: In April 1990, 488 marine fish belonging to 30 species from central Phillipine waters were examined for flesh parasitic infections that may affect their consumability. One species of hemirhamphids and 3 species of belonids harboured plerocercoids of Otobothrium penetrans Linton, 1907 (Proceedings of the U.S. National Museum33, 85–126). This is the first record of this parasite from Pacific fish species. The highest intensity of infection found was 8 in Tylosurus crocodilus. Most of the larvae were located between the dorsal spines of the vertebral column, only 32% were found in the fillets. Based on the present material we give a description of the plerocercoid stage of the species using scanning electron microscopy of the armature and morphometrical measurements. Comparison to results from earlier findings of O. penetrons by Linton (1907; 1924, Proceedings of the U.S. National Museum64, 1–114) and to O. kurisi by Shields (1985, International Journal for Parasitology15: 635–643) lead to the conclusion that the latter species is a synonym for O. penetrans.