Increases in sea-surface temperature due to global warming are a major threat to tropical and subtropical corals as exposure to high water temperatures is the primary cause of coral bleaching. To ...continue receiving high ecosystem services from coral reef ecosystems in the future, it is important to predict the growth conditions of corals and take appropriate countermeasures to protect them at both global and local scales. The Kerama Islands (part of the Nansei Islands, Japan) were selected as the study area. The islands have been designated as a national park and attract substantial tourism, which utilizes the coral reef ecosystem. The selected study site is significant as it is known to act as a source of coral larvae for the surrounding area. In this study, coral bleaching and mortality rates under present and +1.5 °C/+2.0 °C water temperature conditions were estimated using a 1) three-dimensional hydrodynamic model with a spatial resolution of 100 m and 2) statistical model describing the relationship between various environmental parameters and coral bleaching and mortality rates. Applying a local hydrodynamic model enabled us to obtain high-resolution spatial and temporal variations in water temperature and current speed, and these data were used to obtain statistical model data. Coral conservation sites were prioritized based on 1) projections of the spatial distribution of bleaching and mortality rates under global warming conditions and 2) locations of the main diving and conservation points, with the intention of continuing the present use and management locations. The results of this study are expected to contribute to the management of coral reef ecosystems through conservation and adaptation strategies at local scales.
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•Priority conservation sites for corals under rising water temperature were identified•Coral bleaching and death were predicted using hydrodynamic and statistical models•A management plan considering the information on use and conservation was proposed
In recent decades, conflict between Kuril harbor seals (Phoca vitulina stejnegeri) and local fisheries have become a serious problem in Hokkaido, northern Japan. Catch damage in large-scale salmon ...set nets may be mitigated by attaching a rope grid to set net funnels. We investigated the effectiveness of different rope grids on catch damage caused by seals, and evaluated hidden impacts on catch caused by the seals using an underwater camera for observation of seal and salmon behavior coupled with on-board observations of catch and catch damage. The rate of seal prevention was highest for rope grid with 20 cm × 20 cm spacing (97.5 %). The percentage of catch damage in the set net with this rope grid was significantly lower than that for the set net with other rope grid which was easy to enter for seals. We concluded that it is effective to attach an appropriate rope grid to set nets to prevent seals from entering fish bags and to ensure salmon catch amounts. The existence of “hidden damage” was quantitatively revealed via the underwater observation of seals removing salmon from the fish bag, and by comparing the number of salmon between underwater observation and on-board observation.
In this study, we observed the behavior of two age groups of harbor seal (Phoca vitulina richardii), i.e., yearlings, which often become bycaught and individuals 2 yr or older, during their stays at ...salmon set nets at Cape Erimo, Japan. From July to November 2011–2015, acoustic receivers that track tagging seals were attached to three set nets located near the haul‐out site. Our observations showed that the mean visit interval and the mean stay of seals at the set nets during fishing operations were significantly higher than before operations. A cluster analysis, where Cluster 1 consisted of seals that spent a long time at the set nets and Cluster 2 consisted of the other seals, showed that seals in Cluster 1 visited the set nets every day, while Cluster 2 seals visited once every 3–5 d. In addition, age 2 + seals in Cluster 1 stayed longer at regular time frames (at night), suggesting that individuals of this age group in Cluster 1 are highly dependent on the salmon set nets as foraging sites at night. It is especially clear that the set nets near the haul‐out site have influenced the foraging ecology of some seals.
Between 18th October and 7th November 2010, three raccoon dogs were captured in Field Museum Tamakyuryo (FMT), and behaviour at fences was recorded by IP cameras at an enclosure. In this enclosure, ...fencing constructed of diamond-mesh wire netting, 150 cm in height, was used in conjunction with two types of mitigation commonly used in highway fences to prevent raccoon dogs from climbing (PVC board, Trical net). The raccoon dogs escaped successfully by both digging under (adult male) and climbing over the wire fence (yearling), but were not able to climb over the Trical net. Attempts to circumvent the mitigation treatments included biting, stretching the forelegs and/or stretching the nose upwards with standing on rear legs and pawing at the fence. Between October 2011 and October 2012, seven wild raccoon dogs were captured and measured at the TUAT campus, FMT, and Hinode town. These had a minimum paw width of 27 mm, indicating the largest fence mesh size capable of preventing them from climbing the fence. Their minimum lower jaw and canine width was, however, 12.4 mm, and therefore they were able to bite onto even this small Trical net mesh size of. Thus, maximum Trical net mesh size appears to be within 12.4 mm for purpose of bite-proof by raccoon dogs. The maximum gap between the forelegs was 53.6 cm, therefore PVC prevention board larger than this should not be scalable by raccoon dogs.
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