• 14. Life underwater close

Trophy hunting is one of the most controversial issues in the field of biodiversity conservation. In particular, proponents and opponents debate fiercely over whether it poses a threat to hunted populations. Here, we show that trophy hunting constitutes a greater menace to threatened species than previously realized. Because humans value rarity, targeted species that are threatened are likely to be disproportionately hunted, thereby becoming even more vulnerable, which could eventually push them to extinction. With the ten felid species currently hunted for their trophies, we present evidence that (1) the number of killed individuals increases with time, in several cases exponentially, despite population declines, (2) the price of trophies is strongly dependent on species protection status, (3) changes of protection status coincide with counter-intuitive changes of hunting pressures: protection intensification with augmented hunting effort, and protection relaxation with lower effort. This suggests an over-exploitation of trophy-hunted felids and the necessity of a better quota system coupled with reconsidered protection methods.

Abstract Marine gastrotrichs of the Pacific Ocean are poorly known. Here, we report on the finding of a marine chaetonotid gastrotrich of the genus Diuronotus from an intertidal beach within the Sea of Japan in Hokkaido (Japan). The Japanese individual shows a very close resemblance to Diuronotus aspetos. This new record is a consequential extension of its biogeographic range; previous records for representatives of this genus are confined to West Greenland, the North Sea and the east coast of North America. This rarely encountered, but seemingly widespread genus of marine gastrotrichs exemplifies our limited understanding of meiofaunal diversity and distribution patterns caused by sampling bias and insufficient knowledge on nominal species complexes.

AbstractFossil benthic foraminifera are used to trace past methane release linked to climate change. However, it is still debated whether isotopic signatures of living foraminifera from methane-charged sediments reflect incorporation of methane-derived carbon. A deeper understanding of isotopic signatures of living benthic foraminifera from methane-rich environments will help to improve reconstructions of methane release in the past and better predict the impact of future climate warming on methane seepage. Here, we present isotopic signatures (δ13C and δ18O) of foraminiferal calcite together with biogeochemical data from Arctic seep environments from c. 1200 m water depth, Vestnesa Ridge, 79° N, Fram Strait. Lowest δ13C values were recorded in shells of Melonis barleeanus, − 5.2‰ in live specimens and − 6.5‰ in empty shells, from sediments dominated by aerobic (MOx) and anaerobic oxidation of methane (AOM), respectively. Our data indicate that foraminifera actively incorporate methane-derived carbon when living in sediments with moderate seepage activity, while in sediments with high seepage activity the poisonous sulfidic environment leads to death of the foraminifera and an overgrowth of their empty shells by methane-derived authigenic carbonates. We propose that the incorporation of methane-derived carbon in living foraminifera occurs via feeding on methanotrophic bacteria and/or incorporation of ambient dissolved inorganic carbon.

The condition and survival of Antarctic krill (Euphausia superba) strongly depends on sea ice conditions during winter. How krill utilize sea ice depends on several factors such as region and developmental stage. A comprehensive understanding of sea ice habitat use by krill, however, remains largely unknown. The aim of this study was to improve the understanding of the krill’s interaction with the sea ice habitat during winter/early spring by conducting large-scale sampling of the ice–water interface (0–2 m) and comparing the size and developmental stage composition of krill with the pelagic population (0–500 m). Results show that the population in the northern Weddell Sea consisted mainly of krill that were <1 year old (age class 0; AC0), and that it was comprised of multiple cohorts. Size per developmental stage differed spatially, indicating that the krill likely were advected from various origins. The size distribution of krill differed between the two depth strata sampled. Larval stages with a relatively small size (mean 7–8 mm) dominated the upper two metre layer of the water column, while larger larvae and AC0 juveniles (mean 14–15 mm) were proportionally more abundant in the 0- to 500-m stratum. Our results show that, as krill mature, their vertical distribution and utilization of the sea ice appear to change gradually. This could be the result of changes in physiology and/or behaviour, as, e.g., the krill’s energy demand and swimming capacity increase with size and age. The degree of sea ice association will have an effect on large-scale spatial distribution patterns of AC0 krill and on predictions of the consequences of sea ice decline on their survival over winter.

We hypothesize that phytoplankton have the sequential nutrient uptake strategy to maintain nutrient stoichiometry and high primary productivity in the water column. According to this hypothesis, phytoplankton take up the most limiting nutrient first until depletion, continue to draw down non-limiting nutrients and then take up the most limiting nutrient rapidly when it is available. These processes would result in the variation of ambient nutrient ratios in the water column around the Redfield ratio. We used high-resolution continuous vertical profiles of nutrients, nutrient ratios and on-board ship incubation experiments to test this hypothesis in the Strait of Georgia. At the surface in summer, ambient NO3− was depleted with excess PO43− and SiO4− remaining, and as a result, both N : P and N : Si ratios were low. The two ratios increased to about 10 : 1 and 0. 45 : 1, respectively, at 20 m. Time series of vertical profiles showed that the leftover PO43− continued to be removed, resulting in additional phosphorus storage by phytoplankton. The N : P ratios at the nutricline in vertical profiles responded differently to mixing events. Field incubation of seawater samples also demonstrated the sequential uptake of NO3− (the most limiting nutrient) and then PO43− and SiO4− (the non-limiting nutrients). This sequential uptake strategy allows phytoplankton to acquire additional cellular phosphorus and silicon when they are available and wait for nitrogen to become available through frequent mixing of NO3− (or pulsed regenerated NH4). Thus, phytoplankton are able to maintain high productivity and balance nutrient stoichiometry by taking advantage of vigorous mixing regimes with the capacity of the stoichiometric plasticity. To our knowledge, this is the first study to show the in situ dynamics of continuous vertical profiles of N : P and N : Si ratios, which can provide insight into the in situ dynamics of nutrient stoichiometry in the water column and the inference of the transient status of phytoplankton nutrient stoichiometry in the coastal ocean.

Advances in genetic and immunological approaches during the last few decades have transformed medicine and biomedical research. The human genome and the genomes of numerous model organisms are now fully sequenced. Initial exploitation of this wealth of genetic information has begun to revolutionize research on these species, and the applications derived from it. Progress in understanding the ecology of microorganisms (including marine taxa) has followed closely on the heels of these advances, owing to the tremendous benefit afforded by major technological advances in biomedicine. Through the application of these novel approaches and new technologies, marine microbial ecology has moved from a minor footnote within marine biology and biological oceanography during the 1950s and ‘60s to the focus of much of our present interest in the ocean. During the intervening half-century we have learned a great deal regarding the overall abundances, distributions and activities of microorganisms in the sea. Recognition of the extraordinary diversity of marine microbes, the predominant role that they play in global biogeochemical processes, and the potential for natural or engineered microbial products to benefit humankind, has placed marine microbes in the spotlight of both scientific and popular attention. Our fascination with these minute denizens of the ocean is not likely to wane anytime soon. Recent studies have indicated that we still know relatively little about the breadth of microbial diversity in marine ecosystems. In addition, many (most?) of the predominant marine microbial forms in nature have not yet been brought into laboratory culture. Thus, our knowledge is still rudimentary with respect to the spectra of biochemical, physiological and behavioral abilities of these species, and the study of marine microbes will remain a major focus of investigations in marine science well into the foreseeable future. As a large cadre of researchers moves headlong into this work, we can expect many new discoveries and more paradigm shifts regarding the composition and function of marine microbial communities. Los avances en los campos de la genética y la inmunología durante las últimas décadas han transformado las investigaciones de medicina y biomedicina. El genoma humano y el de muchos otros organismos modelo han sido completamente secuenciados. La explotación de esta importante información genética ha empezado a revolucionar la investigación de estas especies y las aplicaciones derivadas de ésta. El progreso en el conocimiento de la ecología de los microorganismos (incluyendo los marinos) ha seguido muy de cerca los avances tecnológicos en biomedicina. La aplicación de nuevas aproximaciones y nuevas tecnologías ha permitido que la ecología microbiana haya pasado de ser una nota a pie de página a ser el tema principal en muchos de los estudios en el océano. Durante los últimos 50 años hemos aprendido aspectos acerca de las abundancias, distribuciones y actividades de los microorganismos marinos. El reconocimiento de la extraordinaria diversidad de los microbios marinos, la importancia de su papel en los ciclos biogeoquímicos y las posibles aplicaciones de los productos fabricados por los microorganismos en beneficio de la humanidad, ha colocado los microbios marinos en el punto de mira tanto de los científicos como del público en general. Nuestra fascinación por estos seres diminutos es posible que prevalezca mucho tiempo. Estudios recientes han indicado que todavía conocemos relativamente poco acerca de la gran diversidad de microorganismos en sistemas marinos. Además, muchos (la mayoría?) de las formas predominantes en la naturaleza todavía no se han logrado cultivar en el laboratorio, lo que nos indica que nuestro conocimiento es todavía rudimentario en relación con las habilidades bioquímicas, fisiológicas y de comportamiento de estos microorganismos. Así pues, previsiblemente, el estudio de los microbios ocupará una gran parte de las investigaciones en ciencias marinas en el futuro. A medida que aumenten el número de investigadores dedicados a estos estudios, se vaticina muchos descubrimientos nuevos, así como nuevos paradigmas relacionados con la composición y función de las comunidades microbianas marinas.

Abstract. It has been previously proposed that alkalinity release from sediments can play an important role in the carbonate dynamics on continental shelves, lowering the pCO2 of seawater and hence increasing the CO2 uptake from the atmosphere. To test this hypothesis, sedimentary alkalinity generation was quantified within cohesive and permeable sediments across the North Sea during two cruises in September 2011 (basin-wide) and June 2012 (Dutch coastal zone). Benthic fluxes of oxygen (O2), alkalinity (AT) and dissolved inorganic carbon (DIC) were determined using shipboard closed sediment incubations. Our results show that sediments can form an important source of alkalinity for the overlying water, particularly in the shallow southern North Sea, where high AT and DIC fluxes were recorded in near-shore sediments of the Belgian, Dutch and German coastal zone. In contrast, fluxes of AT and DIC are substantially lower in the deeper, seasonally stratified, northern part of the North Sea. Based on the data collected, we performed a model analysis to constrain the main pathways of alkalinity generation in the sediment, and to quantify how sedimentary alkalinity drives atmospheric CO2 uptake in the southern North Sea. Overall, our results show that sedimentary alkalinity generation should be regarded as a key component in the CO2 dynamics of shallow coastal systems.

Additional file 4:Table S4: The primer set for the 20 amplicons used in this study. The file shows the designation and the sequence of the primers used, as well as the primer binding sites on the mitochondrial DNA according to the reference sequence (NC_001960.1). (DOCX 16 KB)

Abstract. The diversity and distribution of epipelagic metazooplankton across the Mediterranean Sea was studied along a 3000 km long transect from the eastern to the western basins during the BOUM cruise in summer 2008. Metazooplankton were sampled using both a 120 μm mesh size bongo net and Niskin bottles in the upper 200 m layer at 17 stations. Here we report on the stock, the composition and the structure of the metazooplankton community. The abundance was 4 to 8 times higher than in several previously published studies, whereas the biomass remained within the same order of magnitude. An eastward decrease in abundance was evident, although biomass was variable. Spatial (horizontal and vertical) distribution of metazooplankton abundance and biomass was strongly correlated to chlorophyll-a concentration. In addition, a clear association was observed between the vertical distribution of nauplii and small copepods and the depth of the deep chlorophyll maximum. The distinction between the communities of the eastern and western basins was clearly explained by the environmental factors. The specific distribution pattern of remarkable species was also described.

Accepted: 2009-11-18 資料番号: SA1000984000 著者人数：192名