During the last 2 centuries, southern right whalesEubalaena australiswere hunted to near extinction, and an estimated 150 000 were killed by pre-industrial whaling in the 19th century and illegal ...Soviet whaling in the 20th century. Here we focus on the coastal calving grounds of Australia and New Zealand (NZ), where previous work suggests 2 genetically distinct stocks of southern right whales are recovering. Historical migration patterns and spatially variable patterns of recovery suggest each of these stocks are subdivided into 2 stocks: (1) NZ, comprising NZ subantarctic (NZSA) and mainland NZ (MNZ) stocks; and (2) Australia, comprising southwest and southeast stocks. We expand upon previous work to investigate population subdivision by analysing over 1000 samples collected at 6 locations across NZ and Australia, although sample sizes were small from some locations. Mitochondrial DNA (mtDNA) control region haplotypes (500 bp) and microsatellite genotypes (13 loci) were used to identify 707 individual whales and to test for genetic differentiation. For the first time, we documented the movement of 7 individual whales between the NZSA and MNZ based on the matching of multilocus genotypes. Given the current and historical evidence, we hypothesise that individuals from the NZ subantarctic are slowly recolonising MNZ, where a former calving ground was extirpated. We also suggest that southeast Australian right whales represent a remnant stock, distinct from the southwest Australian stock, based on significant differentiation in mtDNA haplotype frequencies (F
ST= 0.15, p < 0.01; ΦST= 0.12, p = 0.02) and contrasting patterns of recovery. In comparison with significant differences in mtDNA haplotype frequencies found between the 3 proposed stocks (overallF
ST= 0.07, ΦST= 0.12, p < 0.001), we found no significant differentiation in microsatellite loci (overallF
ST= 0.004,G’ST= 0.019, p = 0.07), suggesting ongoing or recent historical reproductive interchange.
Prediction of the distribution of buoyant oil, plastics, flotsam and marine organisms near the ocean surface is a long-standing fundamental problem of practical importance. Here, progress in this ...area during the time of the Gulf of Mexico Research Initiative (GoMRI) (2012-2019) is synthesized, emphasizing the well-known accumulation of floating material into highly concentrated streaks on horizontal scales of meters to 10’s of kilometers. In the pre-GoMRI period, two new paradigms were developed: the importance of submesoscale frontal dynamics on the larger scales and of surface-wave-driven Langmuir turbulence on the smaller scales, with a broad transition occurring near 100 m. Rapid progress resulted from the combination of high resolution numerical modeling tools, mostly developed before GoMRI, and new observational techniques developed during GoMRI. New designs for inexpensive and biodegradable satellite tracked surface drifters and new techniques for aerial tracking of surface drift cards enabled the deployment of thousands of such drifters to measure surface currents and to act as calibrated surrogates for oil. Progress in using radar and optical remote sensing of surface waves enabled mapping of surface currents from ships and aircraft. These new tools, combined with traditional oceanographic tools, enabled a set of coordinated measurement programs which supported and expanded the new paradigms. Floating material was found to both accumulate at submesoscale fronts and to disperse by following these fronts as they moved, leading to both higher concentrations and increased dispersion. Analyses confirmed the distinct submesoscale dynamics of this process and complexity of the resulting fields. Existing tools could be developed into predictive models of submesoscale statistics; prediction of individual submesoscale features is limited by data. Away from fronts, measured rates of accumulation of material in and beneath surface windrows was found to be consistent with Langmuir turbulence, but highly dependent on the rise rate of the material and thus, for oil, on the droplet size. Models of this process were developed and tested and could be further developed into predictive tools. Both the submesoscale and Langmuir processes are sensitive to coupling with surface waves and air-sea flux processes; this is a promising area for future studies.
OBJECTIVES: To evaluate whether screening tests used to identify infectious and neoplastic triggers for immune‐mediated haemolytic anaemia, in particular a complete blood count and differential, ...serum biochemistry profile, urine analysis (including culture), abdominal ultrasound and thoracic radiographs, can identify triggers for steroid‐responsive meningitis‐arteritis. METHODS: Retrospective descriptive review. RESULTS: Twenty‐one steroid‐responsive meningitis‐arteritis cases were identified in which all screening tests had been performed. All cases had changes in complete blood count (including neutrophilia, monocytosis, lymphocytosis, eosinopenia or anaemia); 19 had changes in biochemistry (including hypoalbuminaemia, hyperglobulinaemia, increased alkaline phosphatase activity, hyperphosphataemia, increased total calcium concentration, hypercholesterolaemia, hyperkalaemia, increased urea concentration and increased alanine aminotransferase activity); two cases had an elevated urine protein to creatinine ratio but none had positive urine culture results; no cases had abnormalities on orthogonal radiographs of the thorax; four cases had abnormalities identified on abdominal ultrasound, which following cytological examination suggested inflammation in the absence of pathological organisms. CLINICAL SIGNIFICANCE: Screening tests used to identify infectious and neoplastic triggers in immune‐mediated haemolytic anaemia did not isolate triggers for steroid‐responsive meningitis‐arteritis in the population of dogs under investigation.
Abstract Background Traditionally, 6‐month courses of prednisolone are used to treat steroid‐responsive meningitis‐arteritis (SRMA), but this medication is associated with adverse effects that can ...lead to poor quality of life. Hypothesis/Objectives Resolution of clinical signs and rate of relapse of SRMA would not be significantly different between a 6‐month prednisolone protocol and a 6‐week protocol. Animals Forty‐four hospital cases from multiple referral centers in the United Kingdom (2015‐2019). Twenty of 44 were treated with the 6‐month protocol and 24/44 with the 6‐week protocol. Methods Prospective, randomized trial with 12‐month follow‐up. The same prednisolone protocol reinitiated in the event of relapse. Analysis of relapses with binary logistic and Poisson regression modeling. Results All cases responded to their treatment protocol. Relapses occurred in 6/20 (30%) of the 6‐month protocol and 9/24 (38%) of the 6‐week protocol. There was no statistical difference in the incidence risk of at least 1 relapse between the 2 groups (odds ratio = 1.40; 95% confidence interval CI, 0.40‐4.96, P = 0.60). Among the 15 dogs that relapsed, 10/15 (67%) relapsed once, 3/15 (20%) relapsed twice, and 2/15 (13%) relapsed 3 times. No statistical difference was detected in the incidence rate ratio (IRR) of total relapse events between the 2 groups (IRR = 1.46; 95% CI, 0.61‐3.48; P = 0.40). Conclusions and Clinical Importance “Short” 6‐week prednisolone protocols could be used to treat SRMA, thereby presumably reducing the duration and severity of prednisolone's adverse effects.
The Australian sea lion, Neophoca cinerea, one of the world’s rarest otariids, is notable for an asynchronous, aseasonal breeding chronology. Determining the ecological features that shape the ...genetic structure of marine predators such as Australian sea lions is challenging because their demersal foraging habitat is difficult to observe and quantify. Recent developments in stable isotope screening techniques using milk-dependent pups as proxies for maternal isotope signatures identified temporally stable, alternative (inshore and offshore) foraging ecotypes in adult female Australian sea lions. We combined this technique with mitochondrial DNA (mtDNA) analysis of samples of 40–60% of all pups produced at 17 of the largest South Australian colonies to determine whether ecological specialization in foraging ecotype within and between colonies has shaped maternal population structure within the species. Genetic isolation by distance was apparent at very fine geographical scales with three distinct clusters of colonies that share multiple haplotypes being interspersed with isolated breeding sites. There was no congruence between mtDNA haplotype distribution and foraging ecotypes suggesting that observed behavioural specialization was not maintained along matrilines. We propose that foraging specialization within discrete fine-scale foraging areas and habitats at the individual level limits the dispersive capacity of adult female Australian sea lions which in turn drives population structure. Given this species’ vulnerability to anthropogenic impacts and the high degree of female population structure, determining the extent of male-mediated gene flow in this species is critical. Only then can breeding colony connectivity be established and appropriate management units identified for the species.
► mtDNA and stable isotope data were collected across 17 breeding colonies of Australian sea lions. ► Isolation by distance was significant at 40km. Alternative foraging ecotypes were present at most sites. ► Fine-scale foraging site fidelity may restrict migratory movement. ► Foraging behaviour is not maintained along matrilines. ► Social learning could maintain foraging behaviour over generations.
Abstract
Acrucial region of the ocean surface boundary layer (OSBL) is the strongly-sheared and -stratified transition layer (TL) separating the mixed layer from the upper pycnocline, where a diverse ...range of waves and instabilities are possible. Previous work suggests that these different waves and instabilities will lead to different OSBL behaviours. Therefore, understanding which physical processes occur is key for modelling the TL. Here we present observations of the TL from a Lagrangian float deployed for 73 days near Ocean Weather Station Papa (50°N, 145°W) during Fall 2018. The float followed the vertical motion of the TL, continuously measuring profiles across it using an ADCP, temperature chain and salinity sensors. The temperature chain made depth/time images of TL structures with a resolution of 6cm and 3 seconds. These showed the frequent occurrence of very sharp interfaces, dominated by temperature jumps of O(1)°C over 6cm or less. Temperature inversions were typically small (≲ 10cm), frequent, and strongly-stratified; very few large overturns were observed. The corresponding velocity profiles varied over larger length scales than the temperature profiles. These structures are consistent with scouring behaviour rather than Kelvin-Helmholtz-type overturning. Their net effect, estimated via a Thorpe-scale analysis, suggests that these frequent small temperature inversions can account for the observed mixed layer deepening and entrainment flux. Corresponding estimates of dissipation, diffusivity, and heat fluxes also agree with previous TL studies, suggesting that the TL dynamics is dominated by these nearly continuous 10cm-scale mixing structures, rather than by less frequent larger overturns.
The ocean has depth Lee, K. A.; Huveneers, C.; Duong, T. ...
Marine ecology. Progress series (Halstenbek),
05/2017, Letnik:
572
Journal Article
Recenzirano
Most aquatic animals employ 3-dimensional (3D) movements to fully exploit the resources of the environment they inhabit. Many of these animals, however, are impossible to observe directly, making it ...necessary to use indirect methods of observation such as biotelemetry in order to study them. Despite technological advances with tracking equipment enabling movement to be assessed in 3 dimensions, many studies restrict their analyses to traditional 2-dimensional (2D) space use. We compared 2D and 3D (1) core and home range size, (2) home range overlap and (3) changes in space use in relation to biological and environmental variables of a large, demersal reef-dwelling fish species, the eastern blue groper Achoerodus viridis, tracked using passive acoustic telemetry. Mixed effects models were used to determine differences between the core/home range sizes and home range overlap between the sex of the fish and the breeding and non-breeding seasons. The 2D analyses were unable to detect differences in core and home range sizes between the sexes that were successfully identified by the 3D analyses. 2D analyses only detected differences in home range overlap between the breeding and non-breeding seasons, whereas the 3D analyses found seasonal differences according to the sex of the fish. Two-hourly 2D space use estimates failed to detect differences in space use between fished and protected areas that were detected in the 3D analyses. This study demonstrates that to truly understand how animals use the space they inhabit, we must assess their movement in the full spatial context of their environment.
Interactions between short-beaked common dolphins Delphinus delphis and the fishing industry of South Australia (SA) have lead to serious concerns over the long-term viability of the local dolphin ...population. Common dolphins are gregarious animals with high vagility and are expected to display limited genetic differentiation over large spatial scales. Here, we investigate population genetic structure of southern Australian common dolphins using mitochondrial DNA control region sequences and seven microsatellite markers. We found unexpected levels of genetic differentiation for short-beaked common dolphins over a distance of ~1500 km. Although no genetic structure was observed in common dolphins along the coast of SA, we detected marked differentiation between dolphins from SA and south-eastern Tasmania, suggesting a minimum of two genetic populations in southern Australia. We hypothesize that the ephemeral distribution of small pelagic fish enhances movement and dispersal between dolphin groups at a local level. However, clear differences in water temperature, habitat features and fish abundance between SA and Tasmania may contribute to the contemporary isolation observed between dolphin populations. Our findings have important consequences for developing conservation management strategies, because SA has the largest purse-seine fishery by weight in Australia, and substantial numbers of fatal common dolphin interactions have occurred. In 2004/2005 alone, an estimated 1728 common dolphins were encircled and 377 died over a 7-month period. If these impacts lead to a reduction in population size, it is unlikely that dolphins from the adjacent south-eastern Tasmanian population will replace the lost individuals. Recommendations for assessing the impacts of the fishery are presented. The information herein may also have implications for fisheries-marine mammal interactions in coastal and neritic habitats in other areas of the world. Moreover, we demonstrate that a species commonly thought to be wide ranging can show an unexpected degree of genetic differentiation.
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