2,462 research outputs found
Poverty, Inequality and Growth in Zambia during the 1990s
Zambia, Poverty, Growth, Inequality, Economic reform
New information from fish diets on the importance of glassy flying squid (Hyaloteuthis pelagica) (Teuthoidea: Ommastrephidae) in the epipelagic cephalopod community of the tropical Atlantic Ocean
Squids of the family Ommastrephidae are a vital part of marine food webs and support major fisheries around the world. They are widely distributed in the open ocean, where
they are among the most abundant in number and biomass of nektonic epipelagic organisms. In turn, seven of the 11 genera of this family (Dosidicus, Illex, Martialia, Nototodarus, Ommastrephes, Sthenoteuthis, and Todarodes) are heavily preyed upon by top marine predators, i.e., birds, mammals, and fish, and currently support fisheries in both neritic and oceanic waters (Roper and Sweeney,
1984; Rodhouse, 1997). Their commercial importance has made the large ommastrephids the target of many scientific investigations and their biology is consequently reasonably
well-known (Nigmatullin et al., 2001; Zuyev et al., 2002; Bower and Ichii, 2005). In contrast, much less information is available on the biology and ecological role of the smaller, unexploited species of ommastrephids (e.g., Eucleoteuthis, Hyaloteuthis, Ornithoteuthis, and Todaropsis)
Seabirds as indicators of marine resources:black-browed albatrosses feeding on ommastrephid squids in Kerguelen waters
The species, distributions and abundances of squids in the Southern Ocean are difficult to assess by conventional oceanographic means. The study of the food and feeding ecology of squid-eating predators such as procellariiform seabirds appears to be a supplemental way to collect useful information on cephalopod biology. Regurgitations were collected from 52 chicks of the black-browed albatross Diomedea melanophrys at Kerguelen Island in February 1994. Cephalopod remains were removed and identified by means of beaks, gladius and mantle. Squid beaks of the family Ommastrephidae amounted to 55 % (n = 348) of the accumulated squid beaks. They were also those most often regurgitated in association with partially digested crowns and mantles (90 % of the squid fresh remains, n = 28). Two species of ommastrephids equally dominated the squid diet, Martialia hyadesi (only found once in Kerguelen waters) and a Todarodes species, probably T. angolensis, previously unknown in the area. The concomitant satellite tracking of 16 adult birds over a total of 35 foraging trips identified their main feeding areas as the inner shelf break to the NE and over a bank to the SE of Kerguelen Island. Taken together, albatross dietary and foraging data indicate that juveniles of M. hyadesi and Todarodes sp, concentrate over the upper shelf slope to the east of Kerguelen Island, some of them occurring in the top 5 m of the water column where they are caught by the albatrosses
Campus & alumni news
Boston University Medicine was published by the Boston University Medical Campus, and presented stories on events and topics of interest to members of the BU Medical Campus community. It followed the discontinued publication Centerscope as Boston University Medicine from 1991-2005, then continued as Campus & Alumni News from 2006-2013 before returning to the title Boston University Medicine from 2014-present
Life-history traits of the giant squid Architeuthis dux revealed from stable isotope signatures recorded in beaks
Peer reviewedPreprin
Several dystrophin-glycoprotein complex members are present in crude surface membranes but they are sodium dodecyl sulphate invisible in KCl-washed microsomes from mdx mouse muscle.
International audienceThe dystrophin-glycoprotein complex (DGC) is a large trans-sarcolemmal complex that provides a linkage between the subsarcolemmal cytoskeleton and the extracellular matrix. In skeletal muscle, it consists of the dystroglycan, sarcoglycan and cytoplasmic complexes, with dystrophin forming the core protein. The DGC has been described as being absent or greatly reduced in dystrophin-deficient muscles, and this lack is considered to be involved in the dystrophic phenotype. Such a decrease in the DGC content was observed in dystrophin-deficient muscle from humans with muscular dystrophy and in mice with X-linked muscular dystrophy (mdx mice). These deficits were observed in total muscle homogenates and in partially membrane-purified muscle fractions, the so-called KCl-washed microsomes. Here, we report that most of the proteins of the DGC are actually present at normal levels in the mdx mouse muscle plasma membrane. The proteins are detected in dystrophic animal muscles when the immunoblot assay is performed with crude surface membrane fractions instead of the usually employed KCl-washed microsomes. We propose that these proteins form SDS-insoluble membrane complexes when dystrophin is absent
Analysis of stable isotope ratios in blood of tracked wandering albatrosses fails to distinguish a δ13C gradient within their winter foraging areas in the southwest Atlantic Ocean
Rationale
The main limitation of isotopic tracking for inferring distribution is the lack of detailed reference maps of the isotopic landscape (i.e. isoscapes) in the marine environment. Here, we attempt to map the marine δ13C isoscape for the southwestern sector of the Atlantic Ocean, and assess any temporal variation using the wandering albatross as a model species.
Methods
Tracking data and blood and diet samples were collected monthly from wandering albatrosses rearing chicks at Bird Island, South Georgia, during the austral winter between May and October 2009. The δ13C and δ15N values were measured by mass spectrometry in plasma and blood cells, and related to highly accurate data on individual movements and feeding activity obtained using three types of device: GPS, activity (immersion) loggers and stomach temperature probes.
Results
The tracked birds foraged in waters to the north or northwest of South Georgia, including the Patagonian shelf-break, as far as 2000 km from the colony. The foraging region encompassed the two main fronts in the Southern Ocean (Polar and Subantarctic fronts). The δ13C values varied by only 2.1 ‰ in plasma and 2.5 ‰ in blood cells, and no relationships were found between the δ13C values in plasma and the mean latitude or longitude of landings or feeding events of each individual.
Conclusions
The failure to distinguish a major biogeographic gradient in δ13C values suggest that these values in the south Atlantic Ocean are fairly homogeneous. There was no substantial variation among months in either the δ13C or the δ15N values of plasma or blood cells of tracked birds. As birds did not show a significant change in diet composition or foraging areas during the study period, these results provide no evidence for major temporal variation in stable isotope ratios in consumer tissues, or in the regional marine isoscape in the austral winter of 2009
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