Enlarged lantern size in similar-sized,sympatric, sibling species of Strongylocentrotid sea urchins: from phenotypic accommodation to functional adaptation for durophagy

Strongylocentrotus droebachiensis is a well known omnivorous sea urchin with an unrivalled capacity to destroy North Atlantic kelp forests. S. pallidus is a lesser known, morphologically similar, and closely related species with no record of destructive grazing, despite its larger lantern size. I quantify the lantern size of both species using bivariate allometric analysis, and test the hypothesis that enlarged lantern size facilitates durophagy, the consumption of hard prey, by measuring the feeding capacity of urchins with different lantern sizes when offered a hard-shelled prey, the blue mussel, Mytilus edulis. The results suggest that S. droebachiensis has a limited capacity for durophagous feeding irrespective of lantern size, whereas in S. pallidus the ability to exploit hard shelled prey is positively related to lantern size. This is apparently the first evidence of a relationship between trophic morphology and diet in regular sea urchins. The hypothesis of systematic latitudinal variation in the lantern size of S. pallidus is reappraised and rejected. S. droebachiensis had larger gonads than S. pallidus in field samples, confirming that its small lantern is not impeding nutrient acquisition in shallow habitats.     

Better estimates of soil carbon from geographical data: a revised global approach

Mitigation and Adaptation Strategies for Global Change - Soils hold the largest pool of organic carbon (C) on Earth; yet, soil organic carbon (SOC) reservoirs are not well represented in climate...     

东非和西印度洋沿海水产养殖的发展:食品安全和地方经济的前景和问题

本文回顾了东非和西印度洋的岛屿在海藻、软体动物、鱼类和甲壳类动物的沿海养殖经验和状况.在许多方面,这一地区的沿海水产养殖仍处于发展初期,迫切需要制定旨在提高收入,确保沿海居民对可担负的蛋白质的获得的发展战略.     

Changes in acidity and cation pools of south Swedish soils between 1949 and 1985

The pH of south Swedish soils have decreased considerably during the last 15–35 years. The decrease has occurred throughout the soil profile, not only in the rhizosphere, and is particularly marked in the originally less acid soils. The pH decrease was accompanied by considerable losses of exchangeable Na, K, Mg and Ca, as well as of Zn and (in the originally less acid soils) of Mn. The changes can be prognosticated from the current relationship between soil pH and base saturation and from budget calculations based on lysimeter data.     

Risk-taking behavior in the lesser wax moth: disentangling within- and between-individual variation

Behaviors that appear to be plastic may well be determined by environmental influences during development. Being able to produce a wide range of variants of one kind of behavior, e.g., a very short and a very long response time to a stimulus under different environmental conditions, can be described as behavioral plasticity. How such behavioral reaction norms develop for individuals is poorly understood, but several factors are likely to play a role. We investigated what factors may affect how the risk-taking behavior of the lesser wax moth, Achroia grisella, is shaped during ontogeny. We manipulated larval density to represent the potential intensity of future competition for females in a lek of males, determined adult moths’ reaction to predator signals, and tested for plasticity in the silence response, i.e., the acoustic evasion behavior of the moths during the experiments. While we found no effect of larval density on either the probability or the duration of the silence response, 11 % of the variance in duration could be explained by differences between families, and 30 % of the variance was the result of differences between individuals. We found evidence for habituation to the predator signal, clearly indicating that the silence response is a plastic-enough trait to be adjustable to the immediate environment. These results suggest that the degree to which individuals take risks in the context of acoustic signaling depends more on the immediate context and, possibly, genetic differentiation than it is a product of adaptive developmental plasticity.     

Large donors transfer more sperm,but depletion is faster in a promiscuous hermaphrodite

Males are limited in sperm and seminal fluid, which can lead to prudent sperm allocation across consecutive matings. While sperm depletion is usually considered a population characteristic, we investigated an individual size-related variation in sperm depletion in the promiscuous sea slug Chelidonura sandrana. We found that sperm counts substantially declined across four successive copulations, indicating sperm depletion. Sperm depletion occurred at a disproportionally fast rate in larger sperm donors. Based on our finding of body size-dependent sperm depletion, we further investigated whether this translates into prudent sperm allocation across ejaculates. We found no evidence that slugs adjusted the number of delivered sperm in response to partner body weight, a tight proxy of fecundity. Instead, sperm counts increased with sperm donor body weight. Sperm donation independent of partner body size and—as found in previous work—partner novelty leaves scope for currently unidentified traits like the sperm competition environment to affect male sperm allocation. Alternatively, we propose that, in C. sandrana, a low optimal male mating rate close to the female optimum as indicated by our data may ultimately render indiscriminate sperm allocation the most beneficial male mating strategy.     

A multispecies assessment of wildlife impacts on local community livelihoods

Conflicts between the interests of agriculture and wildlife conservation are a major threat to biodiversity and human well-being globally. Addressing such conflicts requires a thorough understanding of the impacts associated with living alongside protected wildlife. Despite this, most studies reporting on human–wildlife impacts and the strategies used to mitigate them focus on a single species, thus oversimplifying often complex systems of human–wildlife interactions. We sought to characterize the spatiotemporal patterns of impacts by multiple co-occurring species on agricultural livelihoods in the eastern Okavango Delta Panhandle in northern Botswana through the use of a database of 3264 wildlife-incident reports recorded from 2009 to 2015 by the Department of Wildlife and National Parks. Eight species (African elephants [Loxodonta africana], hippopotamuses [Hippopotamus amphibious], lions [Panthera leo], cheetah [Acinonyx jubatus], African wild dogs [Lycaon pictus], hyenas [Crocuta crocuta], leopards [Panthera pardus], and crocodiles [Crocodylus niloticus]) appeared on incident reports, of which 56.5% were attributed to elephants. Most species were associated with only 1 type of damage (i.e., either crop damage or livestock loss). Carnivores were primarily implicated in incident reports related to livestock loss, particularly toward the end of the dry season (May–October). In contrast, herbivores were associated with crop-loss incidents during the wet season (November–April). Our results illustrate how local communities can face distinct livelihood challenges from different species at different times of the year. Such a multispecies assessment has important implications for the design of conservation interventions aimed at addressing the costs of living with wildlife and thereby mitigation of the underlying conservation conflict. Our spatiotemporal, multispecies approach is widely applicable to other regions where sustainable and long-term solutions to conservation conflicts are needed for local communities and biodiversity.     

Impact of Arenicola marina (Polychaeta) on the microbial assemblages and meiobenthos in a marine intertidal flat

The benthic microbial food web can be responsible for a large proportion of benthic carbon cycling yet there are few data on the trophic interactions between this food web and macrobenthos. A large-scale field experiment was conducted to investigate effects of eliminating the polychaete Arenicola marina on benthic microbes (prokaryotes, heterotrophic and autotrophic protists) and metazoan meiofauna in a marine intertidal flat of the North Sea, Germany. Over a period of 2 years, quantity and composition of micro- and meiobenthos from unmanipulated sites were compared to those from sites deplete of lugworms. These grazer treatments were cross-classified with different sediment characteristics (low- and mid-intertidal areas). Lugworm removal resulted in an initial increase in abundance of prokaryotes and nanoflagellates, which became less pronounced in the second year. Ciliates were not affected quantitatively, but in the absence of lugworms, diversity and the proportion of carnivorous forms increased. Meiobenthos (nematodes, ostracods and copepods) were affected only moderately. The observed changes are probably due to a combination of release from grazing/predation pressure, changes in the species composition of higher trophic levels (namely large polychaetes) and altered environmental conditions (such as depth of the oxygenated layer and sediment grain size). Spatial differences between sites of different tidal exposure/grain size appeared to be as large as temporal differences during the 2 years following the manipulation of the system. We conclude that in intertidal sediments, indirect effects due to habitat transformation are as important as direct biological interactions (grazing pressure and competition) for the dynamics of the benthic microbial food web.