Electromagnetic fields (EMFs) emitted from subsea cables have become a common feature of the marine environment with the global expansion of marine renewable energy developments (MREDs). Yet there are very few assessments of potential EMF effects on the behaviour or biology of marine organisms. The limited literature often has conflicting evidence and no standardised testing methodology. The uncertainty is concerning for stakeholders, such as fishers, who are dependent upon the predictability of marine organisms. This paper aimed to critically review the available literature on EMFs to conclude if marine species are at a significant biological risk of contact with energised subsea cables. Presently, there is no evidence of a significant threat to marine organisms encountering subsea cables.
Species coexistence within ecosystems and the stability of patterns of temporal changes
in population sizes are central topics in ecological theory. In the last decade, adaptive
behaviour has been proposed as a mechanism of population stabilization. In particular,
widely distributed adaptive trophic behaviour (ATB), the fitness-enhancing changes in
individuals feeding-related traits due to variation in their trophic environment, may play
a key role in modulating the dynamics of feeding relationships within natural
communities. In this article, we review and synthesize models and results from
theoretical research dealing with the consequences of ATB on the structure and
dynamics of complex food webs. We discuss current approaches, point out limitations,
and consider questions ripe for future research. In spite of some differences in the
modelling and analytic approaches, there are points of convergence: (1) ATB promotes
the complex structure of ecological networks, (2) ATB increases the stability of their
dynamics, (3) ATB reverses Mays negative complexity–stability relationship, and (4)
ATB provides resilience and resistance of networks against perturbations. Current
knowledge supports ATB as an essential ingredient for models of community dynamics,
and future research that incorporates ATB will be well positioned to address questions
important for basic ecological research and its applications.
A growing body of empirical evidence has suggested that biodiversity affects the simultaneous performance of multiple ecosystem functions (i.e. ecosystem multifunctionality). Given increasing environmental variability and uncertainty under global change, an emerging question is how biodiversity influences the stability of multiple functions (i.e. multifunctional stability). We currently know little, however, about the determinants and mechanisms of multifunctional stability, which is of practical importance for ensuring the sustainable provision of multiple functions.
Here, we examined mechanisms contributing to stability (quantified as the ratio of the mean to the standard deviation) of multiple functions related to ecosystem productivity and carbon sequestration, including plant above‐ground and below‐ground productivity, litter production, gross primary productivity and ecosystem respiration, in a large grassland biodiversity experiment in Inner Mongolia.
We found that community‐wide species asynchrony was a strong driver to stabilize multiple functions. Community‐wide asynchrony mediated the positive effects of species richness and response diversity (describing how species with similar effects on ecosystem function respond differently to environmental change) on multifunctional stability. However, species richness had a negative direct effect on multifunctional stability because, although it increased the averaged temporal mean of multiple functions, it strongly increased the averaged temporal standard deviation of multiple functions. The overall effects of species richness on multifunctional stability were thus negative, whereas those of response diversity were positive.
Synthesis. The studied ecosystem functions related to ecosystem productivity and carbon sequestration are important in natural grasslands across the world. We conclude that species asynchrony and response diversity, rather than species richness, are key to the ecosystem multifunctional stability. The loss of response diversity and compensatory mechanisms would likely reduce the long‐term sustainability of grasslands in the face of global change.
n the midwestern United States, maize detritus enters streams draining agricultural land. Genetically modified Bt maize is commonly planted along streams and can possibly affect benthic macroinvertebrates, specifically members of the order Trichoptera, which are closely related to target species of some Bt toxins and are important detritivores in streams. The significance of inputs of Bt maize to aquatic systems has only recently been recognized, and assessments of potential nontarget impacts on aquatic organisms are lacking. We conducted laboratory feeding trials and found that the leaf-shredding trichopteran, Lepidostoma liba, grew significantly slower when fed Bt maize compared to non-Bt maize, while other invertebrate taxa that we examined showed no negative effects. We also used field studies to assess the influence of Bt maize detritus on benthic macroinvertebrate abundance, diversity, biomass, and functional structure in situ in 12 streams adjacent to Bt maize or non-Bt maize fields. We found no significant differences in total abundance or biomass between Bt and non-Bt streams, and trichopterans comprised only a small percentage of invertebrate biomass at all sites (0-15%). Shannon diversity did not differ among Bt and non-Bt streams and was always low (H' range = 0.9-1.9). Highly tolerant taxa, such as oligochaetes and chironomids, were dominant in both Bt and non-Bt streams, and macroinvertebrate community composition was relatively constant across seasons. We used litterbags to examine macroinvertebrate colonization of Bt and non-Bt maize detritus and found no significant differences among litter or stream types. Our in situ findings did not support our laboratory results; this is likely because the streams we studied in this region are highly degraded and subject to multiple, persistent anthropogenic stressors (e.g., channelization, altered flow, nutrient and pesticide inputs). Invertebrate communities in these streams are a product of these degraded conditions, and thus the impact of a single stressor, such as Bt toxins, may not be readily discernable. Our results add to growing evidence that Bt toxins can have sublethal effects on nontarget aquatic taxa, but this evidence should be considered in the context of other anthropogenic impacts and alternative methods of pest control influencing streams draining agricultural regions.
Corn (Zea mays L.) that has been genetically engineered to produce the Cry1Ab protein (Bt corn) is resistant to lepidopteran pests. Bt corn is widely planted in the midwestern United States, often adjacent to headwater streams. We show that corn byproducts, such as pollen and detritus, enter headwater streams and are subject to storage, consumption, and transport to downstream water bodies. Laboratory feeding trials showed that consumption of Bt corn byproducts reduced growth and increased mortality of nontarget stream insects. Stream insects are important prey for aquatic and riparian predators, and widespread planting of Bt crops has unexpected ecosystem-scale consequences.
Avec la dégradation générale des conditions environnementales, beaucoup craignent une 6ème vague d’extinction massive d’espèces. Cette crainte a suscité de nombreuses recherches sur la relation entre la biodiversité et le fonctionnement des écosystèmes, notamment en matière d’écologie des communautés et des écosystèmes. Affrontées au cours des années 1990, ces approches appellent une intégration des deux disciplines. Les auteurs présentent ici quelques éléments de synthèse. C’est une démarche importante car dans le contexte actuel du changement global, l’influence des sociétés humaines est susceptible d’altérer les mécanismes homéostatiques à l’œuvre dans les écosystèmes et, à terme, de déstabiliser la dynamique de nombreux écosystèmes, provoquant ainsi des dommages qui pourraient gravement affecter certaines sociétés humaines. L’édification d’une théorie intégrée à l’interface de l’écologie des communautés et des écosystèmes, est donc plus que jamais d’actualité.
Chapitre n° 2 : Conflits, controverses et paradigmes d’aménagement des cours d’eau
[...] Ce chapitre présente un état de l’art sur la question des conflits et des controverses. Il justifie le recours à ces deux notions pour étudier des questions environnementales et d’aménagement. Il propose un détour par l’histoire de la construction des barrages et par l’histoire de l’aménagement des cours d’eau pour ensuite introduire plus spécifiquement les conflits et controverses liées aux barrages et tisser des liens entre ceux-ci et des changements dans les paradigmes d’aménagement des cours d’eau. En effet, parce qu’elle s’intéresse à la construction de représentations (dans la perspective d’une géographie sociale et culturelle) et de discours (dans une perspective de political ecology), cette thèse accorde une place importante aux temporalités dans l’étude des conflits et des controverses.
Fifty hertz magnetic fields (MFs) induced the expression of heat shock proteins (HSPs) 70 and 90 in immunocytes of the mussel Mytilus galloprovincialis. Animals exposed at 300 μT for three different times (30; 2*30; 3*30 min), did not show differences in the HSP densitometric values in comparison with non-exposed mussels. At 400 μT, exposed animals showed a time-dependent increase in HSP expression as revealed by Western blot. After exposure to 600 μT, the HSP densitometric values were significantly higher than controls but not related to exposure duration. The induction of HSPs is concomitant with the activation of p38 MAP kinase signalling pathway. The present findings suggest the possibility to modulate the expression of HSPs by an appropriate time–intensity magnetic field exposure.
Grasslands in Inner Mongolia have been confronted with unprecedented degradation in recent years. Research on ecosystem stability is important to inform evaluation of the health of degraded grassland ecosystems. We examined synthetic stability, which was defined by the relationships between multiple components of stability, known as multidimensional stability, in grasslands at four stages of degradation (undegraded, slightly degraded, moderately degraded, and intensely degraded) in the Xilin River Basin, Inner Mongolia, China. We analyzed the connections between multidimensional stability and its relationship with four stability components, including community resistance and recovery measured on the basis of plant functional traits, and community functional (aboveground net primary productivity) and structural (Jaccard dissimilarity) variability, calculated on the basis of ten plots from different spatial distributions in a study site. Our results showed that (i) 9 of 17 traits displayed a significant trend along the grazing intensity gradient, indicating a clear turnover of species within communities in response to the grazing intensity gradient; (ii) moderately degraded (C) grasslands showed higher recovery, resistance, and synthetic stability than undegraded (A) and slightly degraded (B) grassland communities overall (recovery: p = 0.026, p = 0.032, for pairs of samples from A and C, and B and C, respectively; resistance: p = 0.024, for a pair of samples from A and C), which conformed with the intermediate disturbance hypothesis and positive diversity-stability relationship; and (iii) the multidimensionality of stability varied between different stages of degradation and were strongly dependent upon the correlations between stability components. Our study is expected to enrich the theory of stability maintenance in grassland ecosystems and provide guidance for grassland restoration and biodiversity conservation.