Ammonium content and buoyancy in midwater cephalopods

The majority of squid families (Teuthoidea: Cephalopoda) exchange sodium for ammonium, creating a low-density fluid that imparts lift for neutral buoyancy. However, previous methods for measuring ammonium did not distinguish between NH₄⁺ and various other amine compounds. The present study, using single column ion chromatography, reassessed the cation concentrations in several midwater cephalopod species. High NH₄⁺ levels were confirmed for histioteuthid, cranchiid, and chiroteuthid and related squids. A strong relationship is reported between ammonium content and body mass in Histioteuthis heteropsis, suggesting a gradual accumulation of ammonium coincident with an ontogenetic migration to greater depths. The bathypelagic squids Bathyteuthis abyssicola and Bathyteuthis berryi, on the other hand, contained very little ammonium but rather contained large quantities of an as yet unidentified cation. The ecological significance of this compound is not yet known. Morphology in Bathyteuthid squids suggests that the unknown cation is contained intracellularly and so, unlike sequestered ammonia, does not diminish the space available for muscle tissue. Accordingly, protein measurements in B. berryi mantle muscle are on par with shallower-living muscular squids, and in situ submersible observations reveal strong locomotory abilities relative to other deep-water squids.     

Using graphical chain models to analyze differences in structural correlates of undernutrition in Benin and Bangladesh

Undernutrition among children is one of the most important health problems in developing countries. In order to understand the complex pathways affecting undernutrition which is crucial for policy interventions, one needs to explicitly model the dependence chain of immediate, intermediate, and underlying factors affecting undernutrition. Graphical chain models are used here to investigate the determinants of undernutrition in Benin and Bangladesh. While the dependence chain affecting undernutrition contains many common elements, the influence of demographic, cultural, and socioeconomic factors seems to have stronger direct and indirect influences in Benin than in Bangladesh, where many socioeconomic and gender related factors have a more direct influence on undernutrition.     

Increase in parasite burden and associated pathology in harbour porpoises (Phocoena phocoena) in West Greenland

Knowledge about parasitism in harbour porpoises and their health status around Greenland is scarce. This study provides knowledge about the poorly studied cetacean in its rapidly changing environment. Parasites and pathological findings in 20 harbour porpoises (Phocoena phocoena) hunted in waters around West Greenland are presented. Carcasses were dissected, and parasitological, histological and bacteriological investigations were carried out. Protozoa (Sarcocystis sp.), Nematoda (Halocercus invaginatus, Stenurus minor, Anisakis simplex sensu lato (s.l.), Crassicauda sp.), Trematoda (Campula oblonga) and Cestoda (Phyllobothrium delphini, Monorygma grimaldii) were found. Parasitic infection of the peribullar cavity and lung with pseudaliid nematodes was found in most animals. Sixty per cent of the porpoises were infected with stomach worms, and trematodes were present in liver and pancreas of 90 and 30 % of the porpoises, respectively. Crassicauda sp. was isolated from perimuscular fascia in 45 % of the animals. This is the first record of tetraphyllidean merocercoids in harbour porpoises. M. grimaldii and P. delphini were found in blubber layer of 15 % and abdominal cavity of 50 % of the porpoises. Bronchopneumonia, gastritis, cholangitis, pancreatitis and panniculitis were almost exclusively associated with parasitic infection and usually mild. Compared with a previous study of Greenlandic porpoises from 1995, a significant increase in severity of parasitic infections and the emergence of new parasite species were observed, most likely associated with changes in diet, influenced by increasing sea temperatures and receding ice cover.     

Short communication. Statolith microstructure from hatchlings of the oceanic squid, Gonatus onyx (Cephalopoda, Gonatidae) from the Northeast Pacific

Statolith microstructure was studied in hatchlings of deepwater-spawned gonatid squid Gonatus onyx, caught between 1350 and 1420 m over a bottom depth of 2100 m in the San Clemente Basin off San Diego, California. It was found that the shape and size of the hatchling statolith were similar to those of the first-check statolith observed in paralarvae and small juveniles of G.onyx. The inner part of the bipartite postnuclear zone (= first-check statolith) is formed during late embryo-genesis, and the first check within the statolith microstructure must be considered as a starting point of increment counting for age estimation of Gonatus spp.