Foraging interactions between Wandering Albatrosses Diomedea exulans breeding on Marion Island and long-line fisheries in the southern Indian Ocean

Wandering Albatrosses Diomedea exulans are frequently killed when they attempt to scavenge baited hooks deployed by long-line fishing vessels. We studied the foraging ecology of Wandering Albatrosses breeding on Marion Island in order to assess the scale of interactions with known long-line fishing fleets. During incubation and late chick-rearing, birds foraged further away from the island, in warmer waters, and showed high spatial overlap with areas of intense tuna Thunnus spp. long-line fishing. During early chick-rearing, birds made shorter foraging trips and showed higher spatial overlap with the local Patagonian Toothfish Dissostichus eleginoides long-line fishery. Tracks of birds returning with offal from the Toothfish fishery showed a strong association with positions at which Toothfish long-lines were set and most diet samples taken during this stage contained fishery-related items. Independent of these seasonal differences, females foraged further from the islands and in warmer waters than males. Consequently, female distribution overlapped more with tuna long-line fisheries, whereas males interacted more with the Toothfish long-line fishery. These factors could lead to differences in the survival probabilities of males and females. Non-breeding birds foraged in warmer waters and showed the highest spatial overlap with tuna long-line fishing areas. The foraging distribution of Marion Island birds showed most spatial overlap with birds from the neighbouring Crozet Islands during the late chick-rearing and non-breeding periods. These areas of foraging overlap also coincided with areas of intense tuna long-line fishing south of Africa. As the population trends of Wandering Albatrosses at these two localities are very similar, it is possible that incidental mortality during the periods when these two populations show the highest spatial overlap could be driving these trends.     

Seasonal variation in the diet of the king penguin (Aptenodytes patagonicus) at sub-Antarctic Marion Island

King penguins are important consumers of marine resources, throughout the year, at the Prince Edward Islands. Meal size varied from 8.5–12.6% of adult mass, depending on the method of determination. In spite of the biases in the analysis favouring the overestimation of squid, fish and, in particular, myctophid fish accounted for the largest proportion of the stomach samples, 87% by wet mass, 75% by numbers and 69% by reconstituted mass. The relative abundance of fish in the diet dropped markedly in winter followed by a subsequent rise to nearly 100% in summer. This rise coincided with an increase in the chick growth rate and the king penguin population at the island and suggests the rise in relative abundance offish reflects a real increase in the availability of fish around the islands.
Juvenile and adult Krefftichthys anderssoni/Protomyctophum tenisoni and adult Electrona carlsbergi were the most common fish consumed. There was an increase in the modal size of K. anderssoni/P. tenisoni throughout the year which we interpret as growth of a single fish population. Juvenile Kondakoviu longimana was the important squid species taken by king penguins. Crustaceans were only rarely recorded in the diet and may have come from digestion of fish and squid stomachs.
This is the first study of the diet of a Southern Ocean pelagic predator that has identified myctophid fish as a major component of its diet. All three important fish species taken by king penguins at Marion Island have a wide distribution throughout the Southern Ocean and consequently may prove to be important dietary components of other Southern Ocean pelagic predators.     

The diet of strap-toothed whales (Mesoplodon layardii)

The food habits of strap-toothed whales ( Mesoplodon layardii ) were examined in detail using stomach contents from 14 stranded whales found on South African and New Zealand coasts. Although a few unidentified fish otoliths and crustacean remains were found in two of these stomachs, 24 species of oceanic squids (some of which occur at a great depth) accounted for 94.8% of counted prey items ( n = 232). Histioteuthis sp. and Taonius pavo were the predominant prey species (25.0 and 17.2% by number, 21.4 and 19.9% by mass, respectively). The presence of sub-Antarctic squid species suggested a northward migration to South African waters in late summer/autumn. Prey sizes were compared between males with fully grown strap-teeth and females/immature males without erupted teeth, using dorsal mantle lengths (DML) and weights of squids estimated from beak measurements. Although females/immature males ate longer squids than males, there was no significant difference in the estimated weights of squids eaten by the two groups. The presence of fully-erupted teeth in adult males, therefore, did not seem to influence the size of prey ingested, even though an adult male could only open its jaws about half as wide as a female. In general, the sizes of cephalopods eaten by strap-toothed whales were not significantly different from those eaten by smaller odontocetes, such as spotted dolphins and dwarf sperm whales, but were significantly smaller than those eaten by larger odontocetes, such as false killer, long-finned pilot, Cuvier's beaked, and southern bottlenose whales.     

Degradation of 4-chlorophenylacetic acid by a Pseudomonas species.

Pseudomonas sp. strain CBS3 was able to utilize 4-chlorophenylacetic acid as the sole source of carbon and energy. When this strain was grown with 4-chlorophenylacetic acid, homoprotocatechuic acid was found to be an intermediate which was further metabolized by the meta-cleavage pathway. Furthermore, three isomers of chlorohydroxyphenylacetic acid, two of them identified as 3-chloro-4-hydroxyphenylacetic acid and 4-chloro-3-hydroxyphenylacetic acid, were isolated from the culture medium. 4-Hydroxyphenylacetic acid was catabolized in a different manner by the glutathione-dependent homogentisate pathway. Degradation enzymes of both of these pathways were inducible.     

Degradation of 4-chlorobenzoic acid by an Arthrobacter species (author's transl)]

An Arthrobacter sp. growing on 4-Chlorobenzoic acid as its sole source of carbon excretes 4-hydroxygenzoic acid and protocatechuic acid into the culture medium. Protocatechuic acid is further attacked by "meta"-cleavage. During growth of the Arthrobacter sp. on benzoic acid cis-cis muconic acid can be isolated from the medium, suggesting the involvement of the "ortho"-cleavage pathway. The enzymes both for the "meta"- and the "ortho"-cleavage pathway are inducible.     

Diet and prey consumption of Antarctic petrels Thalassoica antarctica at Svarthamaren, Dronning Maud Land, and at sea outside the colony

The diet of the Antarctic petrel Thalassoica antarctica was studied during two seasons at Svarthamaren, an inland colony in Dronning Maud Land, Antarctica, and in the pack ice off the coast of Svarthamaren. The most important food (wet mass) at Svarthamaren was crustaceans (67%), fish (29%) and squid (5%); however, individuals collected in the pack ice took mostly fish (87%). The prey composition and lengths of prey are comparable to what has been documented in other studies on this species. Estimates of food consumption by birds breeding at Svarthamaren (ca. 250,000 pairs) suggest that approximately 6500 tonnes of crustaceans, 2800 tonnes of fish and 435 tonnes of squid are consumed during the breeding season. The annual consumptions of these birds are estimated to be 34,100 tonnes of crustaceans, 14,700 tonnes of fish, and 2300 tonnes of squid. Satellite telemetry data indicate that Antarctic petrels from Svarthamaren may fly more than 3000 km during one foraging trip, and thus may cover a huge ocean area to obtain their prey. Received: 1 September 1997 / Accepted: 3 February 1998     

Stone crabs close to the Antarctic Continent: Lithodes murrayi Henderson, 1888 (Crustacea; Decapoda; Anomura) off Peter I Island (68°51′S, 90°51′W)

Live reptant decapod crustaceans have never been collected on the Antarctic continental shelf, although shrimps occur locally in large quantities. Therefore, the collection of four male individuals of the anomuran decapod Lithodes murrayi off Peter I Island, close to the Antarctic Continent, between 180 and 260 m water depth in February 1994 is of particular relevance for further studies on the origin and adaptation of Antarctic decapods. Another five specimens were observed in situ by a remotely operated vehicle at the same location.