Search

Antarctic krill (Euphausia superba) and Ice krill (Euphausia crystallorophias) are key species within Southern Ocean marine ecosystems. Given their importance in regional food webs, coupled with the uncertain impacts of climate change, the on-going recovery of krill-eating marine mammals, and the expanding commercial fishery for Antarctic krill, there is an increasing need to improve current estimates of their circumpolar habitat distribution. Here, we provide an estimate of the austral summer circumpolar habitat distribution of both species using an ensemble of habitat models and updated environmental covariates. Our models were able to resolve the segregated habitats of both species. We find that extensive potential habitat for Antarctic krill is mainly situated in the open ocean and concentrated in the Atlantic sector of the Southern Ocean, while Ice krill habitat was concentrated more evenly around the continent, largely over the continental shelf. Ice krill habitat was mainly predicted by surface oxygen concentration and water column temperature, while Antarctic krill was additionally characterized by mixed layer depth, distance to the continental shelf edge, and surface salinity. Our results further improve understanding about these key species, helping inform sustainable circumpolar management practices.

Global targets for area-based conservation and management must move beyond threshold-based targets alone and must account for the quality of such areas. In the Southern Ocean around Antarctica, a region where key biodiversity faces unprecedented risks from climate change and where there is a growing demand to extract resources, a number of marine areas have been afforded enhanced conservation or management measures through two adopted marine protected areas (MPAs). However, evidence suggests that additional high quality areas could benefit from a proposed network of MPAs. Penguins offer a particular opportunity to identify high quality areas because these birds, as highly visible central-place foragers, are considered indicator species whose populations reflect the state of the surrounding marine environment. We compiled a comprehensive dataset of the location of penguin colonies and their associated abundance estimates in Antarctica. We then estimated the at-sea distribution of birds based on information derived from tracking data and through the application of a modified foraging radius approach with a density decay function to identify some of the most important marine areas for chick-rearing adult penguins throughout waters surrounding Antarctica following the Important Bird and Biodiversity Area (IBA) framework. Additionally, we assessed how marine IBAs overlapped with the currently adopted and proposed network of key management areas (primarily MPAs), and how the krill fishery likely overlapped with marine IBAs over the past five decades. We identified 63 marine IBAs throughout Antarctic waters and found that were the proposed MPAs to be adopted, the permanent conservation of high quality areas for penguin species would increase by between 49 and 100% depending on the species. Furthermore, our data show that, despite a generally contracting range of operation by the krill fishery in Antarctica over the past five decades, a consistently disproportionate amount

The authors present to the Working Group on Ecosystem Monitoring and Management (WG EMM) the scientific background and justification for the development of a marine protected area (MPA) in the Weddell Sea planning area. In accordance with the recommendations by WG-EMM-14 (SC-CAMLR-XXIII, Annex 6), this was done in three separate documents (Part A-C). WG-EMM-16/01 (Part A) sets out the general context of the establishment of CCAMLR-MPAs and provides the background information on the Weddell Sea MPA (WSMPA) planning area; WG-EMM-16/02 (Part B) informs on the data retrieval process and WG-EMM-16/03 (Part C) describes the methods and the results of the scientific analyses as well as the development of the objectives and finally of the borders for the WSMPA. Earlier versions of Parts A-C were already presented at the meetings of EMM and SC-CAMLR in 2015. The Scientific Committee did recognise that the body of science of the background documents (SC-CAMLR-XXXIV/BG/15, BG/16, BG/17) provides the necessary foundation for developing a WSMPA proposal (SC-CAMLR-XXXIV, § 5.11). Here, the authors present the final version of Part A to WG EMM. Part A has undergone final editorial corrections in the 2015/16 intersessional period and contains (i) a synopsis in terms of the establishment of MPAs (chapter 1); (ii) a description of the boundaries of the WSMPA planning area (chapter 2); (iii) a comprehensive, yet succinct, general description of the Weddell Sea ecosystem (chapter 3); (iv) and finally a guidance regarding the future work beyond the development of the scientific basis for the evaluation of a WSMPA (chapter 4).

Objectives:In a climate of scarce research funds, cost-effective exposure assessment becomes more critical. There is a long-acknowledged tradeoff between precision and cost of exposure assessment methods (Winkel and Mathiassen, 1994) that is seldom quantified.The purpose of this study was to compare different sampling strategies for observed trunk posture and determinewhich is the most cost-effective.Knowing the price-performance tradeoffs of observational exposure assessment can help researchers make the most of limited funds.Methods(maximum 150 words)Trunk posture data was observed by trained experts during full work shifts on 126 workers in heavy industry, with repeated measures on 76% of workers. The observed percentage of time spent with trunk flexed more than 60 degrees was recorded and summarized for each work day using the Back-EST sampling method (Village et al 2009). A cost model was developed using previously published cost data (Trask et al 2007) to account for the costs of recruiting companies, workers, and making a full-shift observation of trunk posture. Precision was described in terms of the standard error of the group mean (SEM), using equations from Samuels (1985) that account for multiple measures within companies and workers. Changes in cost efficiency were calculated for sampling strategies employing different combinations of the following: 1-4 companies, 1-12 workers, and 1-4 measures per worker. The case of one recruited company is highlighted here as an example.Results:(maximum 100 words)The SEM declines steeply for the first few additional subjects, while further subjects increase costs considerably with no substantial improvements in precision. Adding repeated measures generally increased costs with smaller gains in precision. In a single-company example, measuring 6 subjects twice (12 measurements total) yields SEM = 0.76 and costs $3929. The same number of measurements can cost up to $4505 with 12 subjects and no repeats, improving the S

Aims There is a long-acknowledged tradeoff between precision and cost of exposure assessment strategies (Winkel and Mathiassen, 1994), but a dearth of literature quantifying this tradeoff. This study compares different sampling strategies for trunk posture observation with respect to monetary costs and statistical efficiency. Methods Experts observed 126 workers in heavy industry during full work shifts, with repeated measures on 76% of workers. The observed percentage of time spent with trunk flexed more than 60 degrees was recorded and summarized for each work day using the Back-EST sampling method (Village et al 2009). A model of costs associated with the data sampling strategy was developed using previously published data (Trask et al 2007), accounting for the costs of recruiting companies and workers, and of observing full work shifts. Statistical performance was described as standard error of the mean (SEM). Post hoc, a selection of sampling strategies were simulated to demonstrate the empirical trade-off between cost and efficiency for different sampling strategies. Results: Figure 1 shows the family of curves resulting when 1 to 10 workers are measured 1 to 4 times within a single company. The SEM declines steeply for the first few additional subjects, while further subjects increase costs considerably with no substantial improvements in precision. Adding repeated measures generally increased costs with smaller gains in precision. Discussion/conclusions: This study informs design of posture observation sampling campaigns; the ‘mesh’ of sampling strategies in the figure demonstrates the maximum precision level that can be achieved for a given cost, as well as the minimum cost for a given level of precision. This allows researchers to make informed decisions on the use of limited resources when designing ergonomic studies

Udgivelsesdato: 2006/7

We studied the mortality from lung and pleural cancers in a cohort of 62, 937 male workers employed for at least 1 year in the pulp and paper industry in 13 countries during 1945 to 1996. Mill departments were classified according to probability and level of exposure to asbestos on the basis of available dust measurements and mill-specific information on exposure circumstances. Thirty-six percent of workers were classified as ever exposed to asbestos. Standardized mortality ratios of lung cancer were 0.99 (95 % confidence interval [CI], 0.90 to 1.08) among unexposed and 1.00 (95 % CI, 0.90 to 1.11) among ever exposed workers. The number of pleural cancer deaths among unexposed workers was 10, that among exposed workers was 14, most of which occurred among maintenance workers. In internal analyses, a trend in mortality from either neoplasm was suggested for estimated cumulative exposure to asbestos, weighted for the individual probability of exposure within the department and for duration of exposure (relative risk for lung cancer for 0.78+ f/cc-years, as compared with = 0.01 f/cc-years: 1.44, 95 % CI, 0.85 to 2.45, corresponding relative risk for pleural cancer: 2.43, 95% CI, 0.43 to 13.63). Despite a possible nondifferential misclassification of exposure and outcome, this study suggests that the carcinogenic effect of asbestos can be detected among workers employed in industries such as the pulp and paper industry, in which it is not considered to be a major hazard.