ALBERT

Description: In a midoceanic region of the northeast Atlantic, patches of freshly deposited phytodetritus were discovered on the sea floor at a 4500 m depth in July/August 1986. The color of phytodetritus was variable and was obviously related to the degree of degradation. Microscopic analyses showed the presence of planktonic organisms from the euphotic zone, e.g., cyanobacteria, small chlorophytes, diatoms, coccolithophorids, silicoflagellates, dinoflagellates, tintinnids, radiolarians, and foraminifers. Additionally, crustacean exuviae and a great number of small fecal pellets, “minipellets,” were found. Although bacteria were abundant in phytodetritus, their number was not as high as in the sediment. Phytodetrital aggregates also contained a considerable number of benthic organisms such as nematodes and special assemblages of benthic foraminifers. Pigment analyses and the high content of particulate organic carbon indicated that the phytodetritus was relatively undegraded. Concentrations of proteins, carbohydrates, chloroplastic pigments, total adenylates, and bacteria were found to be significantly higher in sediment surface samples when phytodetritus was present than in equivalent samples collected at the same stations in early spring prior to phytodetritus deposition. Only the electron transport system activity showed no significant difference between the two sets of samples, which may be caused by physiological stress during sampling (decompression, warming). The chemical data of phytodetritus samples displayed a great variability indicative of the heterogeneous nature of the detrital material. The gut contents of various megafauna (holothurians, asteroids, sipunculids, and actiniarians) included phytodetritus showing that the detrital material is utilized as a food source by a wide range of benthic organisms. Our data suggest that the detrital material is partly rapidly consumed and remineralized at the sediment surface and partly incorporated into the sediment. Incubations of phytodetritus under simulated in situ conditions and determination of the biological oxygen demand under surface water conditions showed that part of its organic matter can be biologically utilized. Based on the measured standing stock of phytodetritus, it is estimated that 0.3–3% of spring primary production sedimented to the deep-sea floor. Modes of aggregate formation in the surface waters, their sedimentation, and distribution on the seabed are discussed.

Description: The diet of Northern Rockhopper Penguins Eudyptes chrysocome moseleyi breeding on Gough Island, south Atlantic Ocean was studied, during November 1984, 1985 and 1986 by stomach content analysis. Rockhopper Penguins fed chiefly on the euphausiids Thysanoessa gregaria, Euphausia lucens and E. similis. Fish and squid were of minor importance by mass but constituted the largest individual prey items.

Description: The Imperial Cormorant Phalacrocorax atriceps is an inshore foraging, diving seabird (Cooper 1985) distributed throughout the southern hemisphere south of 45°S (Watson 1975). A brief description of the diet of the Imperial Cormorant at Marion Island has been published (Blankley 1981). We present here a more comprehensive report based on food samples collected throughout the year.

Description: The western margin of the Tauera Window (Eastern Alps) is defined by a low angle westward dipping fault zone of potently We disp lacement. Ductile deformation of the fault rocks results in a carpet of mylonites up to 400 metres thick. Evidence from shear criteria and the excision of part of the Cretaceous-Tertiary metamorphic edifice both indicate normal displacements, and relative movement of Austroalpine nappe complex towards the west. The Sterzing-Steinach mylonite zone overprints the Alpine nappe edifice. Movements occurred on the cooling path of the Tauern metamorphism, and may be as recent as Middle Miocene. The Kinematics and geometry of the mylonite zone constrain two likely t ectonic explanations that are both compatible with secondary thining of a thick orogenic wedge. (1) Ute the Austroalpine nappe pile due to tectonic unroofing of the Tauern window. (2) Continental escape by east-west stretching of the Alpine orogenic wedge in response to continental collision.

Description: Chemical composition of Zostera marina L. seed and shoots was determined. Morphology and histochemistry of mature seeds were studied by fluorescence, brightfield and scanning electron microscopy to locate storage constituents in the seed. Starch content in the mature seed was 51% and was the major storage reserve in the embryo and a minor component in the testa. Starch in the shoots ranged from 0.3 to 2.3%. Protein, located in the embryo as small protein bodies, comprised about 9.0% of the seed. Protein in shoots ranged from 6–15%. Protein quality of both seeds and shoots resembled corn in composition, and the first limiting amino acid was lysine. Shoots were high in minerals, fiber and ash, while seeds were lower in these constituents. Fat was low (0.3–1.7%) in both shoots and seeds.

Description: The diet of Ommastrephes bartramii (Lesueur, 1821) was determined by analysing the stomach contents of 73 squid caught in the South-West Atlantic Ocean. There were three main prey groups, Cephalopoda (in 82% of the squid stomachs), Osteichthyes (34%) and Crustacea (18%). Cannibalism was common. Squid of the families Histioteuthidae and Enoploteuthidae and other teuthoids were less frequent in the diet. The fish prey was predominantly Myctophidae, of various species. The bulk of the prey was mesopelagic species that migrate into the epipelagic layers at night.

Description: Feeding strategies are different when adult Illex illecebrosus prey on large (trout) and small fish (mummichogs). Attacks on trout are characterized by (1) rotation as the squid changes from tail‐first to head‐first swimming; (2) an approach phase involving rapid acceleration towards the prey; (3) a tracking phase where the squid slowly follows the trout; (4) the capture phase. No tracking phase is present in attacks on mummichogs. These differences in feeding strategies can be explained by performance limitations of the squid jet propulsion system. Head‐first acceleration rates in Illex are low (max. = 12 m • s−2) and maneuverability poor compared to fish. A large fish could thus out‐perform an attacking squid if forced into evasive action. The tracking phase is a type of oceanic stalking strategy designed to bring the squid into close proximity to larger fish. The behaviour is not necessary when attacking small fish due to their low swimming speeds.

Description: Oxygen consumption and ammonia excretion rates were investigated in young Octopus maya (hatching to 139 days old; 0.11–81.23 g wet body weight, BW; 22.5–23.9°C), young squids of Loligo forbesi (hatching to 45 days old; 9.4–115.3 mg BW; 12.3–13.1°C) and young squids of Lolliguncula brevis (2.00–39.98 g BW; 23.8–24.7°C). Except at hatching, oxygen consumption and ammonia excretion rates on an individual basis (M) of these three cephalopods increased linearly with increasing body weight (BW) expressed as M = aBWb . Values of b for oxygen consumption were 0.900, 0.910 and 0.848 and for ammonia excretion were 0.744, 0.809 and 0.751 for O. maya, L. forbesi and L. brevis, respectively. Among the three species the value a varied widely, while b was similar for both oxygen consumption and ammonia excretion rates. Based upon these data, metabolism for hatchlings of O. maya and L. forbesi was estimated to be relatively lower than that of older juveniles. The O/N ratios for hatchlings of O. maya and L. forbesi were relatively high and indicate an apparent dependence upon lipids in the immediate post‐hatching period, followed by standard protein energy utilization thereafter.

Description: The first recorded specimens of Scaeurgus unicirrhus from the South-East Atlantic are described. Five males and two females were captured on the Valdivia Bank, Walvis Ridge, between 24 and 27°S, 400 miles off the Namibian coast. They are compared with specimens caught from other areas, and historical and geographic surveys of the species are made.