Variation in the fatty acid composition of the blubber in Cape fur seals (Arctocephalus pusillus pusillus) and the implications for dietary interpretation

Analysis of the fatty acid (FA) composition of blubber is a valuable tool in interpreting the diet of marine mammals. This technique is based on the principle that particular FA present in prey can be incorporated largely untransformed into predator adipose tissue stores, thereby providing biochemical signatures with which to identify prey species. Several studies of phocid seals and cetaceans have documented vertical stratification in the FA composition of blubber such that inferences about diet may vary greatly depending on the layer of the blubber that is analysed. It is not known whether blubber in otariid seals (fur seals and sea lions) also displays vertical stratification in FA composition. Furthermore, it is not known whether the FA composition of blubber is uniform in these species. In the present study, the vertical and regional variation in FA composition of blubber was investigated in seven adult female Cape fur seals (Arctocephalus pusillus pusillus). The proportion of monounsaturated fatty acids (MUFA) was greater in the outer (43.6±1.3%) than inner portion (40.9±1.2%; t20=5.59, P<0.001) whereas the proportions were greater in the inner than outer portions for saturated fatty acids (23.6±0.5% and 21.9±0.6%, respectively, t20 = 5.31, P<0.001) and polyunsaturated fatty acids (PUFA, 35.5±0.7% and 34.5±0.7%, respectively, t20 = 3.81, P < 0.001). There was an inverse relationship between MUFA and PUFA in the blubber, independent of sampling location. In addition, with the exception of the inner portion from non-lactating females, blubber from the mammary area had the highest proportions of 18:1ω9c and total MUFA, followed by blubber from the rump and neck, suggesting that the deposition and mobilisation of blubber lipids may not be uniform around the body in otariid seals. These results support the need for blubber tissue to be sampled from the same site on animals, and to the full depth of the blubber layer, to minimise variation in FA profiles that could occur if different sites and depths were sampled. Such standardisation of sampling will further aid in interpreting diet in otariid seals using the FA Signature Analysis approach.

Differences in foraging strategy and maternal behaviour between two sympatric fur seal species at the Crozet Islands

Marine top-predators such as marine mammals forage in a heterogeneous environment according to their energetic requirements and to the variation in environmental characteristics. In this study, the behaviour of breeding females in 2 sympatric fur seal species, Antarctic fur seal Arctocephalus gazella and Subantarctic fur seal A. tropicalis, was investigated in relation to foraging effort. Foraging effort was hypothesised to be greater in Antarctic fur seal than in Subantarctic fur seal due to their shorter lactation period. Using satellite telemetry, time-depth recorders and satellite images of sea-surface temperature and chlorophyll a concentration, the foraging grounds, the at-sea activity budgets and the environmental features were determined for both species breeding on the Crozet Archipelago. Foraging cycle duration was similar for the 2 species, and the seals exhibited similar at-sea activity budgets. Only the proportion of time spent at sea was higher in Antarctic fur seals. Separate foraging areas were identified for the 2 species. Antarctic fur seal distribution was related to bathymetric features, while we did not find any direct relationship between chlorophyll a concentration and seal foraging areas. Our results suggest that Antarctic fur seals tend to respond to the higher needs of their pups by having a higher foraging efficiency and concentrating their foraging activity in the most productive areas.

Habitat selection by female Australian fur seals (Arctocephalus pusillus doriferus)

1. Numerous studies have determined the foraging areas of marine apex predators and investigated their relationship to oceanographic features. Most of these, however, have concentrated on surface-feeding seabirds or epipelagic-foraging marine mammals and there is little information on habitat selection in benthic divers.

2. Satellite telemetry was used during the winters of 2001-2003 to determine the foraging areas of 48 female Australian fur seals (Arctocephalus pusillus doriferus) from four breeding sites in northern Bass Strait whose colonies together represent > 80% of the total species population.

3. All individuals foraged over the shallow continental shelf of Bass Strait supporting earlier studies that suggested the species is an exclusively benthic forager. Individual females showed a high degree of foraging site-fidelity and several foraging 'hot spot' areas could be identified.

4. Analysis of habitat use indicated that individuals selected areas with depths of 60-80 m significantly more (λ = 0.216, P<0.001) than any other bathymetric class. There was also evidence for foraging areas being influenced by SST, with individuals selecting regions of 16.0-16.8 C SST (λ = 0.008, P<0.01), but not surface chlorophyll-a concentration (P> 0.05).

5. Temporal analysis of at-sea movements indicated, due to their primarily benthic foraging mode, the areas frequented by female Australian fur seals did not overlap substantially with areas targeted by commercial fisheries. An exception to this was in far eastern Bass Strait where the Otter Trawl component of the Commonwealth Trawl Sector is highly active over the continental shelf and encompasses the areas frequented by females from The Skerries colony.

Foraging trip strategies and habitat use during late pup rearing by lactating Australian fur seals

Australian fur seals (Arctocephalus pusillus doriferus) are the most conspicuous and abundant marine mammal in shelf waters of south-eastern Australia. To successfully rear offspring, the females must encounter sufficient prey on each foraging trip out of a central place for periods up to11 months each year. We investigated foraging trip strategies and habitat use by the females in three winter–spring periods, 2001–03, from four colonies that span the species’ latitudinal range and contribute 80% of pup production. Trip durations of 37 females averaged 6.1±0.5 (s.e.) days, although >90% of the seal’s time at sea was spent <150 km travel (<2 days) away. Most females exhibited strong fidelities to individually preferred hotspots Females from colonies adjacent to productive shelf-edge waters generally had shorter trips, had smaller ranges, foraged closer to colonies and exhibited less diversity in trip strategies than did those from colonies more distant from a shelf-edge. From a management perspective, there was minimal overlap (<1%) between where females foraged and a system of marine reserves established in 2007, suggesting that habitats visited by lactating Australian fur seals currently receive minimal legislative protection

Individual foraging site fidelity in lactating New Zealand fur seals : Continental shelf vs. oceanic habitats

Wide-ranging marine central place foragers often exhibit foraging site fidelity to oceanographic features over differing spatial scales (i.e., localized coastal upwellings and oceanic fronts). Few studies have tested how the degree of site fidelity to foraging areas varies in relation to the type of ocean features used. In order to determine how foraging site fidelity varied between continental shelf and oceanic foraging habitats, 31 lactating New Zealand fur seals (Arctocephalus australis forsteri1) were satellite tracked over consecutive foraging trips (14–108 d). Thirty-seven foraging trips were recorded from 11 females that foraged on the continental shelf, in a region associated with a coastal upwelling, while 65 foraging trips were recorded from 20 females that foraged in oceanic waters. There were no significant differences in the mean bearings (to maximum distance) of individual's consecutive foraging trips, suggesting individual fidelity to foraging areas. However, overlap in area and time spent in area varied considerably between continental shelf and oceanic foragers. Females that foraged on the continental shelf had significantly greater overlap in consecutive foraging trips when compared to females that foraged in oceanic waters (overlap in 5 × 5 km grid cells visited on consecutive trips 55.9%± 20.4% and 13.4%± 7.6%, respectively). Females that foraged on the continental shelf also spent significantly more time within the same grid cell than females that foraged in oceanic waters (maximum time spent in 5 × 5 km grid cells: 14%± 5% and 4%± 2%, respectively). This comparatively high foraging site fidelity may reflect the concentration of productivity associated with a coastal upwelling system, the Bonney Upwelling. Lower foraging site fidelity recorded by seals that foraged in oceanic waters implies a lower density/larger scale habitat, where prey are more dispersed or less predictable at fine scales, when compared to the continental shelf region.

A review of the adaptive significance and ecosystem consequences of zooplankton diel vertical migrations

Diel vertical migration (DVM) by zooplankton is a universal feature in all the World's oceans, as well as being common in freshwater environments. The normal pattern involves movement from shallow depths at night to greater depths during the day. For many herbivorous and omnivorous mesozooplankton that feed predominantly near the surface on phytoplankton and microzooplankton, minimising the risk of predation from fish seems to be the ultimate factor behind DVM. These migrants appear to use deep water as a dark daytime refuge where their probability of being detected and eaten is lower than if they remained near the surface. Associated with these vertical movements of mesozooplankton, predators at higher trophic levels, including invertebrates, fish, marine mammals, birds and reptiles, may modify their behaviour to optimise the exploitation of their vertically migrating prey. Recent advances in biotelemetry promise to allow the interaction between migrating zooplankton and diving air-breathing vertebrates to be explored in far more detail than hitherto.

Behaviour and buoyancy regulation in the deepest-diving reptile : the leatherback turtle

In the face of the physical and physiological challenges of performing breath-hold deep dives, marine vertebrates have evolved different strategies. Although behavioural strategies in marine mammals and seabirds have been investigated in detail, little is known about the deepest-diving reptile – the leatherback turtle (Dermochelys coriacea). Here, we deployed tri-axial accelerometers on female leatherbacks nesting on St Croix, US Virgin Islands, to explore their diving strategy. Our results show a consistent behavioural pattern within dives among individuals, with an initial period of active swimming at relatively steep descent angles (∼–40 deg), with a stroke frequency of 0.32 Hz, followed by a gliding phase. The depth at which the gliding phase began increased with the maximum depth of the dives. In addition, descent body angles and vertical velocities were higher during deeper dives. Leatherbacks might thus regulate their inspired air-volume according to the intended dive depth, similar to hard-shelled turtles and penguins. During the ascent, turtles actively swam with a stroke frequency of 0.30 Hz but with a low vertical velocity (∼0.40 ms–1) and a low pitch angle (∼+26 deg). Turtles might avoid succumbing to decompression sickness (‘the bends’) by ascending slowly to the surface. In addition, we suggest that the low body temperature of this marine ectotherm compared with that of endotherms might help reduce the risk of bubble formation by increasing the solubility of nitrogen in the blood. This physiological advantage, coupled with several behavioural and physical adaptations, might explain the particular ecological niche the leatherback turtle occupies among marine reptiles.

Indicators of the impact of climate change on migratory species

The Bonn Convention on the Conservation of Migratory Species of Wild Animals adopted a Resolution in 2005 recognising the impacts of climate change on migratory species. It called on Contracting Parties to undertake more research to improve our understanding of these impacts and to implement adaptation measures to reduce foreseeable adverse effects. Given the large diversity of taxa and species affected by climate change, it is impossible to monitor all species and effects thereof. However, it is likely that many of the key ecological and physical processes through which climate change may impact wildlife could be monitored using a suite of indicators, each comprising parameters of species/populations or groups of species as proxies for wider assemblages, habitats and ecosystems. Herein, we identify a suite of 17 indicators whose attributes could reveal negative impacts of climate change on the global status of migratory species: 4 for birds, 4 for marine mammals, 2 for sea turtles, 1 for fish, 3 for land mammals and 3 for bats. A few of these indicators would be relatively straightforward to develop, but most would require additional data collation, and in many cases methodological development. Choosing and developing indicators of the impacts of climate change on migratory species is a challenge, particularly with endangered species, which are subject to many other pressures. To identify and implement conservation measures for these species, indicators must account for the full ensemble of pressures, and link to a system of alerts and triggers for action.

Travelling through a warming world: climate change and migratory species

Long-distance migrations are among the wonders of the natural world, but this multi-taxon review shows that the characteristics of species that undertake such movements appear to make them particularly vulnerable to detrimental impacts of climate change. Migrants are key components of biological systems in high latitude regions, where the speed and magnitude of climate change impacts are greatest. They also rely on highly productive seasonal habitats, including wetlands and ocean upwellings that, with climate change, may become less food-rich and predictable in space and time. While migrants are adapted to adjust their behaviour with annual changes in the weather, the decoupling of climatic variables between geographically separate breeding and non-breeding grounds is beginning to result in mistimed migration. Furthermore, human land-use and activity patterns will constrain the ability of many species to modify their migratory routes and may increase the stress induced by climate change. Adapting conservation strategies for migrants in the light of climate change will require substantial shifts in site designation policies, flexibility of management strategies and the integration of forward planning for both people and wildlife. While adaptation to changes may be feasible for some terrestrial systems, wildlife in the marine ecosystem may be more dependent on the degree of climate change mitigation that is achievable.

The accuracy of Fastloc-GPS locations and implications for animal tracking

Over recent years, a major breakthrough in marine animal tracking has occurred with the advent of Fastloc-GPS that provides highly accurate location data even for animals that only surface briefly such as sea turtles, marine mammals and penguins. We assessed the accuracy of Fastloc-GPS locations using fixed trials of tags in which >45 000 locations were obtained. Procedures for determining the speed of travel and heading were developed by simulating tracks and then adding Fastloc-GPS location errors. The levels of detail achievable for speed and heading estimates were illustrated by using empirical Fastloc-GPS data for a green turtle (Chelonia mydas, Linnaeus, 1758) travelling over 3000 km across the Indian Ocean. The accuracy of Fastloc-GPS locations varied as a function of the number of GPS satellites used in the location calculation. For example, when Fastloc-GPS locations were calculated using 4 GPS satellites, 50% of locations were within 36 m and 95% within 724 m of the true position. These values improved to 18 and 70 m, respectively, when 6 satellites were used. Simulations indicated that for animals travelling around 2·5 km h-1 (e.g. turtles, penguins and seals) and depending on the number of satellites used in the location calculation, robust speed and heading estimates would usually be obtained for locations only 1-6 h apart. Fastloc-GPS accuracy is several orders of magnitude better that conventional Argos tracking or light-based geolocation and consequently will allow new insights into small-scale movement patterns of marine animals.

Assessment of body surface temperature in cetaceans: an iterative approach

A transferência de energia térmica da superfície corporal para a água é provavelmente o aspecto mais importante do equilíbrio térmico em mamíferos marinhos, mas os respectivos cálculos dependem do conhecimento da temperatura da superfície, T S, cuja medição direta em animais em liberdade constitui um problema difícil de resolver. Um método iterativo é proposto para a predição de T S de cetáceos em liberdade, a partir da temperatura corporal profunda, da velocidade de deslocamento e da temperatura e propriedades termodinâmicas da água.

Cryptococcosis: epidemiology, fungal resistance, and new alternatives for treatment

Cryptococcosis is an important systemic mycosis and the third most prevalent disease in human immunodeficiency virus (HIV)-positive individuals. The incidence of cryptococcosis is high among the 25 million people with HIV/acquired immunodeficiency syndrome (AIDS), with recent estimates indicating that there are one million cases of cryptococcal meningitis globally per year in AIDS patients. In Cryptococcus neoformans, resistance to azoles may be associated with alterations in the target enzyme encoded by the gene ERG11, lanosterol 14α-demethylase. These alterations are obtained through mutations, or by overexpressing the gene encoding. In addition, C. gattii and C. neoformans present a heteroresistance phenotype, which may be related to increased virulence. Other species beyond C. neoformans and C. gattii, such as C. laurentii, have been diagnosed mainly in patients with immunosuppression. Infections of C. albidus have been isolated in cats and marine mammals. Recent evidence suggests that the majority of infections produced by this pathogen are associated with biofilm growth, which is also related with increased resistance to antifungal agents. Therefore, there is a great need to search for alternative antifungal agents for these fungi. The search for new molecules is currently occurring from nanoparticle drugs of plant peptide origin. This article presents a brief review of the literature regarding the epidemiology of cryptococcosis, as well as fungal resistance and new alternatives for treatment. © 2013 Springer-Verlag Berlin Heidelberg.

Toxic heritage: maternal transfer of pyrethroid insecticides and sunscreen agents in dolphins from Brazil

Pyrethroids (PYR) and UV filters (UVF) were investigated in tissues of paired mother-fetus dolphins from Brazilian coast in order to investigate the possibility of maternal transfer of these emerging contaminants. Comparison of PYR and UVF concentrations in maternal and fetal blubber revealed Franciscana transferred efficiently both contaminants to fetuses (F/M > 1) and Guiana dolphin transferred efficiently PYR to fetuses (F/M > 1) different than UVF (F/M < 1). PYR and UVF concentrations in fetuses were the highest-ever reported in biota (up to 6640 and 11,530 ng/g lw, respectively). Muscle was the organ with the highest PYR and UVF concentrations (p < 0.001), suggesting that these two classes of emerging contaminants may have more affinity for proteins than for lipids. The high PYR and UVF concentrations found in fetuses demonstrate these compounds are efficiently transferred through placenta. This study is the first to report maternal transfer of pyrethroids and UV filters in marine mammals.

Chemical contaminants in juvenile gray whales (Eschrichtius robustus) from a subsistence harvest in Arctic feeding grounds

Gray whales are coastal migratory baleen whales that are benthic feeders. Most of their feeding takes place in the northern Pacific Ocean with opportunistic feeding taking place during their migrations and residence on the breeding grounds. The concentrations of organochlorines and trace elements were determined in tissues and stomach contents of juvenile gray whales that were taken on their Arctic feeding grounds in the western Bering Sea during a Russian subsistence harvest. These concentrations were compared to previously published data for contaminants in gray whales that stranded along the west coast of the US during their northbound migration. Feeding in coastal waters during their migrations may present a risk of exposure to toxic chemicals in some regions. The mean concentration (standard error of the mean, SEM) of Σ PCBs [1400 (130) ng/g, lipid weight] in the blubber of juvenile subsistence whales was significantly lower than the mean level [27 000 (11 000) ng/g, lipid weight] reported previously in juvenile gray whales that stranded in waters off the west coast of the US. Aluminum in stomach contents of the subsistence whales was high compared to other marine mammal species, which is consistent with the ingestion of sediment during feeding. Furthermore, the concentrations of potentially toxic chemicals in tissues were relatively low when compared to the concentrations in tissues of other marine mammals feeding at higher trophic levels. These chemical contaminant data for the subsistence gray whales substantially increase the information available for presumably healthy animals.

A Preliminary Note on Trichinosis Investigations in Alaska

Trichinosis in the arctic regions of the world has received considerable attention during recent years, particularly since the work of Roth (1948) in Greenland. In Connell's (1949) review of arctic trichinosis some Alaskan and Canadian records were included but, until now, little has been known of the status of the disease in Alaska. Information available at the present time indicates that the incidence of trichinosis is high in circumpolar carnivores and that marine mammals have a definite place in its epizootiology. Present knowledge cannot explain the survival of trichinosis in marine mammal populations, but it is evident that they may serve as important sources of human infection. Up to the present time the following mammals from Alaska have been found to be infected: From the arctic coast-polar bear, Thalarctas maritimus; arctic fox, Alapex lagapus irmuitus; red fox, Vulpes fulva alascemis; white whale, Delphinapterus leucas; Eskimo dog. From south of the Brooks Range--brown and grizzly bears, Ursus spp.; wolf, Canis lupus ssp.; wolverine. Gula l. luscus. At the time of writing, nearly ail species of land carnivores in Alaska have been examined as well as many other mammalian species less likely to be infected, including various rodents, shrews, and others.