Objectives Currently, active euthanasia is legalized in only 7 countries worldwide. These countries have encountered problems in its implementation. The study aims to summarize the practical clinical problems in the literature on active euthanasia. Methods A systematic literature review was conducted using 140 works consisting of 130 articles from PubMed and EthxWeb and data from 10 euthanasia laws. Results After reviewing the specific problems reported to be associated with euthanasia in each country, 5 problems were extracted: many ambiguous conditions with room for interpretation, insufficient assurance of voluntariness, response to requests for euthanasia due to psychological distress, conscientious objection, and noncompliance by medical professionals. Significance of results Multiple ambiguous conditions that are open to interpretation can result in a “slippery slope phenomenon.” An insufficient guarantee of voluntariness violates the principle of respect for autonomy, which is the underlying justification for euthanasia. In cases of euthanasia due to mental anguish, a distinction between a desire for death caused by psychological pain alone prompted by mental illness and a desire for death caused by mental symptoms prompted by physical illness is essential. Conscientious objection should remain an option because of the heavy burden placed on doctors who perform euthanasia. Noncompliance by medical professionals due to ignorance and conflicts regarding euthanasia is contrary to procedural justice.

Climate change is leading to novel species interactions and profoundly altering ecosystems. In marine systems, tropical and subtropical species are increasing in higher latitudes. This has been linked to the deforestation of temperate coastlines, as direct effects of ocean warming combine with increased herbivory from tropical and sub-tropical fishes and lead to the decline of canopy-forming kelp. Here, we tested the hypothesis that this deforestation may be facilitated by greater palatability of temperate kelp and other canopy seaweeds compared to tropical taxa. We used multiple-choice filmed feeding field experiments and chemical analyses to measure the palatability of temperate and tropical seaweeds from Tosa Bay (southeastern Japan) and we used single-species feeding assays to measure changes in consumption of the kelp Ecklonia cava throughout the year. We found no evidence that temperate seaweeds are more palatable to herbivorous fish. In the multiple-choice assays, consumption was concentrated on both tropical and temperate Sargassum species, which are ephemeral and peak in abundance in the spring/early summer. Consumption of the kelp Ecklonia cava peaked during the autumn, when Sargassum species are absent. The highest levels of kelp herbivory coincide with the reproductive season for E. cava and may contribute to the long-term decline of these kelp forests in southern Japan.

An Ecklonia cava bed has been developing on an oŠshore breakwater at Usa, Kochi Prefecture (western Japan) after seeding in 2003. To investigate the patterns of habitat use byˆsh in this aŠorested kelp bed, a monthly underwater visual transect survey was conducted between November 2013 and October 2015. A total of 73 species within 38 families were observed during this period. We observed a higher density of some species in the kelp bed compared with those in the adjacent unvegetated area, including permanent resident species, such as Girella punctata and Calotomus spinidens, seasonal resident species, such as Scombrops boops, which utilized the kelp bed as a juvenile habitat, and transient resident species, such as Fistularia commersonii, which utilized the kelp bed as a foraging ground. Theˆsh assemblage structures were compared between the aŠorested kelp bed and a natural kelp bed within the same prefecture, during winter, early summer, and early autumn. No diŠerences were found