Publications by authors named "Christina Lockyer"

The Harbour porpoise (Phocoena phocoena) is a highly mobile cetacean species primarily occurring in coastal and shelf waters across the Northern hemisphere. It inhabits heterogeneous seascapes broadly varying in salinity and temperature. Here, we produced 74 whole genomes at intermediate coverage to study Harbour porpoise's evolutionary history and investigate the role of local adaptation in the diversification into subspecies and populations.

View Article and Find Full Text PDF

Rationale: Stable isotope analysis of growth layers in sperm whale teeth dentine can provide valuable insight into individual long-distance displacements and diet. Although treating teeth half-sections with formic acid and rubbing their surface with a graphite pencil improves growth layer visibility and reduces sampling error, previous studies mostly used untreated half-sections as the effect that this treatment may have on stable isotope ratios in dentine is unknown. The present study investigates the treatment effect on stable C and N isotope ratios in sperm whale teeth dentine.

View Article and Find Full Text PDF

The population structure of the highly mobile marine mammal, the harbor porpoise (Phocoena phocoena), in the Atlantic shelf waters follows a pattern of significant isolation-by-distance. The population structure of harbor porpoises from the Baltic Sea, which is connected with the North Sea through a series of basins separated by shallow underwater ridges, however, is more complex. Here, we investigated the population differentiation of harbor porpoises in European Seas with a special focus on the Baltic Sea and adjacent waters, using a population genomics approach.

View Article and Find Full Text PDF

Concentrations of PCBs, organochlorine pesticides (OCPs), brominated flame retardants and a suite of relevant metabolites of these POPs, in all 175 different compounds, were determined in liver and plasma of traditionally hunted pilot whales (n=14 males and n=13 females of different age groups) from the Faroe Islands. The main objectives of this study were to determine differences in the presence and concentrations of the compounds in the liver and plasma, how they depend on developmental stage (calves, sub adults, and adult females), and to assess maternal transfer of the compounds to suckling calves. Generally, the lipid weight (lw) concentrations of quantified POPs in the liver and plasma of pilot whales were positively correlated, and lw concentrations of most POPs did not differ between these matrices.

View Article and Find Full Text PDF

In pelagic species inhabiting large oceans, genetic differentiation tends to be mild and populations devoid of structure. However, large cetaceans have provided many examples of structuring. Here we investigate whether the sperm whale, a pelagic species with large population sizes and reputedly highly mobile, shows indication of structuring in the eastern North Atlantic, an ocean basin in which a single population is believed to occur.

View Article and Find Full Text PDF

Profiles of seven compounds of perfluoro-alkyl substances (PFASs) were compared among three species of top predators from the Danish North Sea: the white-beaked dolphin (Lagenorhynchus albirostris), the harbor porpoise (Phocoena phocoena), and the harbor seal (Phoca vitulina). The seals had higher total burdens (757.8 ng g(-1) ww) than the dolphins (439.

View Article and Find Full Text PDF

The effects of climate change on marine ecosystems and in particular on marine top predators are difficult to assess due to, among other things, spatial variability, and lack of clear delineation of marine habitats. The banks of West Greenland are located in a climate sensitive area and are likely to elicit pronounced responses to oceanographic changes in the North Atlantic. The recent increase in sea temperatures on the banks of West Greenland has had cascading effects on sea ice coverage, residency of top predators, and abundance of important prey species like Atlantic cod (Gadus morhua).

View Article and Find Full Text PDF

Eighty-five stranded or bycaught harbor porpoises collected from the Danish North Sea between 1980 and 2005 were analyzed for perfluorochemicals in the liver. PFOS was the predominant compound, making up on average 88.9% of the ∑PFC, followed by PFOSA (7.

View Article and Find Full Text PDF

The effect of age, sex, nutritive condition and organochlorine concentration on blubber retinoid concentrations was examined in 74 common dolphins incidentally caught off northwestern Spain. Age and blubber lipid content were strong determinants of the retinoid concentrations in males, while these variables did not account for the variation found in females. Retinoids were positively correlated with organochlorines in males and negatively in females.

View Article and Find Full Text PDF

The concentrations of butyltin (summation operatorBT=TBT+DBT+MBT) and mercury (Hg) were determined in the liver of 35 harbour porpoises (Phocoena phocoena), which were found dead along the coastlines or caught as by-catch in the Danish North Sea and the Inner Danish waters. In addition, three harbour porpoises hunted in West Greenland were analysed. High levels of butyltin and mercury, within the range of 68-4605 mg BT/kg ww and 0.

View Article and Find Full Text PDF

During the 1995 hunting season, 75 harbour porpoises (Phocoena phocoena) were sampled in three locations in West Greenland: Maniitsoq, Nuuk, and Paamiut. Sex, age, morphometrics, reproductive condition, and organochlorine compound (OC) levels in blubber were determined for each individual. OC levels were extremely low and, therefore considered unlikely to affect the population adversely: mean blubber concentrations, expressed on lipid weight basis were 1.

View Article and Find Full Text PDF