The rate of metabolism in marine animals: environmental constraints, ecological demands and energetic opportunities

The rates of metabolism in animals vary tremendously throughout the biosphere. The origins of this variation are a matter of active debate with some scientists highlighting the importance of anatomical or environmental constraints, while others emphasize the diversity of ecological roles that organisms play and the associated energy demands. Here, we analyse metabolic rates in diverse marine taxa, with special emphasis on patterns of metabolic rate across a depth gradient, in an effort to understand the extent and underlying causes of variation. The conclusion from this analysis is that low rates of metabolism, in the deep sea and elsewhere, do not result from resource (e.g. food or oxygen) limitation or from temperature or pressure constraint. While metabolic rates do decline strongly with depth in several important animal groups, for others metabolism in abyssal species proceeds as fast as in ecologically similar shallow-water species at equivalent temperatures. Rather, high metabolic demand follows strong selection for locomotory capacity among visual predators inhabiting well-lit oceanic waters. Relaxation of this selection where visual predation is limited provides an opportunity for reduced energy expenditure. Large-scale metabolic variation in the ocean results from interspecific differences in ecological energy demand.     

Increased viviparity of marine parasites at high latitudes

For the first time, Thorson's rule, that non-pelagic development increases with latitude, is shown to apply to a group of marine parasites. Relative and absolute numbers of species of viviparous Monogenea, gill parasites of fish, increase with increasing latitude. The gradient can be explained by the inability, in cold waters, of (a) free larvae to locate suitable habitats (hosts) and/ or (b) small invertebrates to produce pelagic larvae in sufficient numbers. Viviparous Monogenea are also more common in cold than in warm freshwater, but have not been fund in the deep sea.     

The rotifer fauna of peat-swamps in southern Thailand

Different taxa have had different degrees of success in invading and proliferating in the deep sea. The reasons for these differences are not well known, and exemplars need to be studied to provide insight as to factors that lead to success in the deep sea. Because the abundance of the deep-sea fauna taken as a whole declines with depth, the absolute abundance of a taxon is not an appropriate metric of its success. Rather, a taxon whose abundance declines as rapidly as or less rapidly than the general trend should be considered successful. In this paper, I used the macrofauna to define the general trend of abundance change with depth. When I compared the trend of abundance of harpacticoids to that for macrofauna, I found that harpacticoid abundance decreased less rapidly. Thus, harpacticoids are unusually successful in the deep sea. The reasons for their success are unknown, but I discuss three possible explanations.     

What constitutes fair shared decision-making in global health research collaborations?

Funders (located primarily in high-income countries) and high-income country researchers have historically dominated decision-making within global health research collaborations: from setting agendas and research design to determining how data are collected and analysed and what happens with findings and outputs. The ethical principle of shared decision-making has been proposed as a way to help address these imbalances within collaborations and to reduce semicolonial and exploitative forms of global health research. It is important to be clear about what shared decision-making means in order to ensure that it is not done in a tokenistic, shallow way. Thus far, the principle’s content has not been examined and articulated in detail. This paper aims to start the process of delineating a concept of fair shared decision-making as a minimum standard for global health research. Using two hypothetical case examples, the paper will demonstrate that global health research practice is often inconsistent with ideal shared decision-making. In such instances, it can be difficult to decide whether shared decision-making within collaborations is fair. The paper describes how the two cases do not meet criteria for unfair or non-ideal shared decision-making, despite having potentially morally troubling features. The nuances of these examples of research practice help to generate clearer ideas about how to judge fairness in shared decision-making. The paper concludes by presenting ideas about when soft power can be fairly employed between high-income-country and low- and middle-income-country partners and what fair compromise agreements may look like in shared decision-making.     

From principles to practice: a spatial approach to systematic conservation planning in the deep sea

Increases in the demand and price for industrial metals, combined with advances in technological capabilities have now made deep-sea mining more feasible and economically viable. In order to balance economic interests with the conservation of abyssal plain ecosystems, it is becoming increasingly important to develop a systematic approach to spatial management and zoning of the deep sea. Here, we describe an expert-driven systematic conservation planning process applied to inform science-based recommendations to the International Seabed Authority for a system of deep-sea marine protected areas (MPAs) to safeguard biodiversity and ecosystem function in an abyssal Pacific region targeted for nodule mining (e.g. the Clarion–Clipperton fracture zone, CCZ). Our use of geospatial analysis and expert opinion in forming the recommendations allowed us to stratify the proposed network by biophysical gradients, maximize the number of biologically unique seamounts within each subregion, and minimize socioeconomic impacts. The resulting proposal for an MPA network (nine replicate 400 × 400 km MPAs) covers 24% (1 440 000 km²) of the total CCZ planning region and serves as example of swift and pre-emptive conservation planning across an unprecedented area in the deep sea. As pressure from resource extraction increases in the future, the scientific guiding principles outlined in this research can serve as a basis for collaborative international approaches to ocean management.     

The olfactory receptor gene repertoires in secondary-adapted marine vertebrates: evidence for reduction of the functional proportions in cetaceans

An olfactory receptor (OR) multigene family is responsible for the well-developed sense of smell possessed by terrestrial tetrapods. Mammalian OR genes had diverged greatly in the terrestrial environment after the fish-tetrapod split, indicating their importance to land habitation. In this study, we analysed OR genes of marine tetrapods (minke whale Balaenoptera acutorostrata, dwarf sperm whale Kogia sima, Dall's porpoise Phocoenoides dalli, Steller's sea lion Eumetopias jubatus and loggerhead sea turtle Caretta caretta) and revealed that the pseudogene proportions of OR gene repertoires in whales were significantly higher than those in their terrestrial relative cattle and also in sea lion and sea turtle. On the other hand, the pseudogene proportion of OR sequences in sea lion was not significantly higher compared with that in their terrestrial relative (dog). It indicates that secondary perfectly adapted marine vertebrates (cetaceans) have lost large amount of their OR genes, whereas secondary-semi-adapted marine vertebrates (sea lions and sea turtles) still have maintained their OR genes, reflecting the importance of terrestrial environment for these animals.     

How many demersal fish species in the deep sea? A test of a method to extrapolate from local to global diversity

Grassle and Maciolek (1992) estimated that there were of the order of 107 species of benthic macro-invertebrates in the world's deep sea soft sediments. Their estimate was extrapolated from the 798 species they sampled and the pattern of species diversity observed along a 176km transect on the continental slope of the northeast Atlantic Ocean. Relative to the deep sea invertebrate fauna, the deep sea fish fauna has been better sampled, at least in the upper 1500m. To test the validity of the Grassle and Maciolek method of extrapolation, we applied it to data from a survey of fishes along the continental slope off western Australia, a diverse and previously unsurveyed region. The resulting global estimate for the deep sea demersal fishes – 60000 species – was then compared with the number described to date, about 2650 species, and an estimate of total extant species. Our estimate, which considers the proportion of new species found in little-explored regions of the world ocean, such as off western Australia, and the number of new species expected in future taxonomic revisions, is a total of 3000–4000 species. The Grassle and Maciolek method appears invalid as a means to extrapolate global biodiversity from local surveys.     

可培养海洋放线菌生物多样性的研究进展

海洋放线菌是新药开发和天然活性产物的重要来源,海洋放线菌的生物多样性是代谢产物功能多样性的基础,因此研究可培养放线菌的生物多样性具有重要的意义。综述了近年来可培养的海洋放线菌生物多样性的研究进展,尤其是海绵共附生放线菌、深海放线菌和海洋固有放线菌的研究进展,对可培养的海洋放线菌的分离培养方法,包括样品处理、培养基的选择等进行了重点介绍,并对未培养海洋放线菌的分离培养进行了探讨,强调了建立区域性海洋放线菌菌种及基因资源库的重要性。     

“深层海水”对小鼠耐受力的影响

本文将90只条件相同小鼠随机分成3组,A组服90 ppm(mg/mL)深层海水,B组服45 ppm深层海水,C组服自来水,均自由饮用30 d,第31 d时行耐缺氧实验、游泳耐力实验,断头采血,测定血细胞、肝肾功能及各种酶的变化。结果表明,在相同的饲养条件下三组体重无明显改变。A、B组比C组小鼠力竭游泳时间及耐缺氧时间显著延长(P<0.05),耗氧量显著减少(P<0.05),天冬氨酸氨基转移酶、肌酸激酶、肌酸肌酶同工酶降低,有显著差别(P<0.05),血常规、肝肾功能、电解质无显著性差异。因而,深层海水能改善酶的功能,减少小鼠的耗氧量,能明显增强小鼠的耐受力。     

深海微生物资源研究开发技术进展

深海微生物由于生存环境的特殊性而具有各种与陆地和浅海微生物不同的功能,这些特殊功能具有重要的应用价值,是争夺激烈的深海热点资源之一。近年来,不断有新的研究技术和方法得到应用,推动了深海微生物资源的获取、研究和开发。对深海微生物菌株和基因资源研究开发方面的技术发展以及工作策略进行了综述与讨论。