Comparing environmental impacts of deep-seabed and land-based mining: A defensible framework.

The crises of climate change and biodiversity loss are interlinked and must be addressed jointly. A proposed solution for reducing reliance on fossil fuels, and thus mitigating climate change, is the transition from conventional combustion-engine to electric vehicles. This transition currently requires additional mineral resources, such as nickel and cobalt used in car batteries, presently obtained from land-based mines. Most options to meet this demand are associated with some biodiversity loss. One proposal is to mine the deep seabed, a vast, relatively pristine and mostly unexplored region of our planet. Few comparisons of environmental impacts of solely expanding land-based mining versus extending mining to the deep seabed for the additional resources exist and for biodiversity only qualitative. Here, we present a framework that facilitates a holistic comparison of relative ecosystem impacts by mining, using empirical data from relevant environmental metrics. This framework (Environmental Impact Wheel) includes a suite of physicochemical and biological components, rather than a few selected metrics, surrogates, or proxies. It is modified from the "recovery wheel" presented in the International Standards for the Practice of Ecological Restoration to address impacts rather than recovery. The wheel includes six attributes (physical condition, community composition, structural diversity, ecosystem function, external exchanges and absence of threats). Each has 3-5 sub attributes, in turn measured with several indicators. The framework includes five steps: (1) identifying geographic scope; (2) identifying relevant spatiotemporal scales; (3) selecting relevant indicators for each sub-attribute; (4) aggregating changes in indicators to scores; and (5) generating Environmental Impact Wheels for targeted comparisons. To move forward comparisons of land-based with deep seabed mining, thresholds of the indicators that reflect the range in severity of environmental impacts are needed. Indicators should be based on clearly articulated environmental goals, with objectives and targets that are specific, measurable, achievable, relevant, and time bound.

Assessing cadmium-based quantum dots effect on the gonads of the marine mussel Mytilus galloprovincialis.

This study assesses the sex-specific effects induced by CdTe QDs, on the marine mussel Mytilus galloprovincialis in comparison to its dissolved counterpart. A 14 days exposure to CdTe QDs and dissolved Cd was conducted (10 µg Cd L-1), analysing Cd accumulation, oxidative stress, biotransformation, metallothionein and oxidative damage in the gonads. Both Cd forms caused significant antioxidant alterations, whereby QDs were more pro-oxidant, leading to oxidative damage, being females more affected. Overall, biochemical impairments on gonads of M. galloprovincialis demonstrate that the reproductive toxicity induced by CdTe QDs in mussels are sex-dependent and mediated by oxidative stress and lipid peroxidation. It is crucial to acknowledge how gametes are affected by metal-based nanoparticles, such as Cd-based QDs. As well as understanding the potential changes they may undergo at the cellular level during gametogenesis, embryogenesis and larval development potentially leading to serious impacts on population sustainability and ecosystem health.

Are shallow-water shrimps proxies for hydrothermal-vent shrimps to assess the impact of deep-sea mining?

Polymetallic seafloor massive sulphide deposits are potential targets for deep-sea mining, but high concentrations of metals (including copper - Cu) may be released during exploitation activities, potentially inducing harmful impact. To determine whether shallow-water shrimp are suitable ecotoxicological proxies for deep-sea hydrothermal vent shrimp the effects of waterborne Cu exposure (3 and 10 days at 0.4 and 4 µM concentrations) in Palaemon elegans, Palaemon serratus, and Palaemon varians were compared with Mirocaris fortunata. Accumulation of Cu and a set of biomarkers were analysed. Results show different responses among congeneric species indicating that it is not appropriate to use shallow-water shrimps as ecotoxicological proxies for deep-water shrimps. During the evolutionary history of these species they were likely subject to different chemical environments which may have induced different molecular/biochemical adaptations/tolerances. Results highlight the importance of analysing effects of deep-sea mining in situ and in local species to adequately assess ecotoxicological effects under natural environmental conditions.

Environmental relevant levels of the cytotoxic drug cyclophosphamide produce harmful effects in the polychaete Nereis diversicolor.

Cytotoxic drugs applied in chemotherapy enter the aquatic environment after patient's metabolism and excretion, in both main compounds and their respective metabolites. The increased consumption and discharge of these drugs raise concern on the genotoxic burden to non-target aquatic species, due to their unselective action on DNA. Settlement and adsorption of cytotoxic drugs to aquatic sediments pose risks to benthic species through chronic exposure. The aim of the present study was to assess the effects induced by the anticancer drug cyclophosphamide (CP) on the polychaete Nereis diversicolor, after 14 days of exposure to environmental relevant concentrations (10, 100, 500 and 1000 ng L-1). Burrowing impairment, neurotoxicity (Acetylcholinesterase - AChE activity), oxidative stress (superoxide dismutase - SOD; catalase - CAT; glutathione peroxidases - GPXs activities), biotransformation (glutathione-S-transferases - GST), oxidative damage (lipid peroxidation - LPO) and genotoxicity (DNA damage) were assessed. Burrowing impairments were higher at the lowest CP concentrations tested. The higher CP levels tested (500 and 1000 ng L-1) induced a significant inhibition on the enzymatic antioxidant system (SOD, GPx) and on GST activity. DNA damage was also significant at these concentrations as an outcome of CP metabolism, and high levels of oxidative damage occurred. The results showed that the prodrug CP was metabolically activated in the benthic biological model N. diversicolor. In addition to the potential cytotoxic impact likely to be caused in aquatic species with similar metabolism, N. diversicolor proved to be reliable and vulnerable to the cytotoxic mode of action of CP, even at the lower doses.

Development of an ecotoxicological protocol for the deep-sea fauna using the hydrothermal vent shrimp Rimicaris exoculata.

In light of deep-sea mining industry development, particularly interested in massive-sulphide deposits enriched in metals with high commercial value, efforts are increasing to better understand potential environmental impacts to local fauna. The aim of this study was to assess the natural background levels of biomarkers in the hydrothermal vent shrimp Rimicaris exoculata and their responses to copper exposure at in situ pressure (30MPa) as well as the effects of depressurization and pressurization of the high-pressure aquarium IPOCAMP. R. exoculata were collected from the chimney walls of the hydrothermal vent site TAG (Mid Atlantic Ridge) at 3630m depth during the BICOSE cruise in 2014. Tissue metal accumulation was quantified in different tissues (gills, hepatopancreas and muscle) and a battery of biomarkers was measured: metal exposure (metallothioneins), oxidative stress (catalase, superoxide dismutase, glutathione-S-transferase and glutathione peroxidase) and oxidative damage (lipid peroxidation). Data show a higher concentration of Cu in the hepatopancreas and a slight increase in the gills after incubations (for both exposed groups). Significant induction of metallothioneins was observed in the gills of shrimps exposed to 4µM of Cu compared to the control group. Moreover, activities of enzymes were detected for the in situ group, showing a background protection against metal toxicity. Results suggest that the proposed method, including a physiologically critical step of pressurizing and depressurizing the test chamber to enable the seawater exchange during exposure to contaminants, is not affecting metal accumulation and biomarkers response and may prove a useful method to assess toxicity of contaminants in deep-sea species.

Temporal change in deep-sea benthic ecosystems: a review of the evidence from recent time-series studies.

Societal concerns over the potential impacts of recent global change have prompted renewed interest in the long-term ecological monitoring of large ecosystems. The deep sea is the largest ecosystem on the planet, the least accessible, and perhaps the least understood. Nevertheless, deep-sea data collected over the last few decades are now being synthesised with a view to both measuring global change and predicting the future impacts of further rises in atmospheric carbon dioxide concentrations. For many years, it was assumed by many that the deep sea is a stable habitat, buffered from short-term changes in the atmosphere or upper ocean. However, recent studies suggest that deep-seafloor ecosystems may respond relatively quickly to seasonal, inter-annual and decadal-scale shifts in upper-ocean variables. In this review, we assess the evidence for these long-term (i.e. inter-annual to decadal-scale) changes both in biologically driven, sedimented, deep-sea ecosystems (e.g. abyssal plains) and in chemosynthetic ecosystems that are partially geologically driven, such as hydrothermal vents and cold seeps. We have identified 11 deep-sea sedimented ecosystems for which published analyses of long-term biological data exist. At three of these, we have found evidence for a progressive trend that could be potentially linked to recent climate change, although the evidence is not conclusive. At the other sites, we have concluded that the changes were either not significant, or were stochastically variable without being clearly linked to climate change or climate variability indices. For chemosynthetic ecosystems, we have identified 14 sites for which there are some published long-term data. Data for temporal changes at chemosynthetic ecosystems are scarce, with few sites being subjected to repeated visits. However, the limited evidence from hydrothermal vents suggests that at fast-spreading centres such as the East Pacific Rise, vent communities are impacted on decadal scales by stochastic events such as volcanic eruptions, with associated fauna showing complex patterns of community succession. For the slow-spreading centres such as the Mid-Atlantic Ridge, vent sites appear to be stable over the time periods measured, with no discernable long-term trend. At cold seeps, inferences based on spatial studies in the Gulf of Mexico, and data on organism longevity, suggest that these sites are stable over many hundreds of years. However, at the Haakon Mosby mud volcano, a large, well-studied seep in the Barents Sea, periodic mud slides associated with gas and fluid venting may disrupt benthic communities, leading to successional sequences over time. For chemosynthetic ecosystems of biogenic origin (e.g. whale-falls), it is likely that the longevity of the habitat depends mainly on the size of the carcass and the ecological setting, with large remains persisting as a distinct seafloor habitat for up to 100 years. Studies of shallow-water analogs of deep-sea ecosystems such as marine caves may also yield insights into temporal processes. Although it is obvious from the geological record that past climate change has impacted deep-sea faunas, the evidence that recent climate change or climate variability has altered deep-sea benthic communities is extremely limited. This mainly reflects the lack of remote sensing of this vast seafloor habitat. Current and future advances in deep-ocean benthic science involve new remote observing technologies that combine a high temporal resolution (e.g. cabled observatories) with spatial capabilities (e.g. autonomous vehicles undertaking image surveys of the seabed).

Dependence of release variables in the shot put.

When the shot is released above a horizontal plane, range from this point depends on release height, speed and angle. Measured distance is the sum of this range and horizontal distance of the release point from the throwing circle edge. Optimal release conditions can be calculated only if the dependence of release velocity on other variables, due to thrower limitations, is known. Experiments on two shot-putters investigated the hypothesis that there are constraint relationships among these four release parameters. A variable scaling scheme, using measurement of impact point and the known magnitude of g, corrected 2D data from one camera for out-of-plane motion and yielded accurate estimates of release parameters. Multivariate regression analyses determined approximate constraint surfaces limiting performance. Achievable release speed decreases with increasing release angle at about 1.7(m/s)/rad and decreases with increasing release height at about 0.8(m/s)/m, with only small differences in sensitivities between the throwers. Horizontal release distance also decreases with increasing release angle at about 1.7m/rad and increases with increasing release height at about 1.3m/m, again with only small differences between the two throwers. Optimal release conditions producing maximum range for a particular athlete can be determined using similar constraints for that athlete.

Choline acetyltransferase and somatostatin levels in aged Microcebus murinus brain.

beta-Amyloid protein (beta-AP) deposits, analoguous to those found in Alzheimer's disease (AD) are observed in the brain of aging Microcebus murinus. Because choline acetyltransferase (ChAT) activity and somatostatin (SRIH) content are consistently decreased in AD, we tested whether such changes could be observed in middle aged to aged Microcebus cerebral cortex and whether they were accompanied by beta-AP deposits. A positive correlation was observed between age and ChAT activity. By HPLC, SRIH immunoreactivity eluted as four peaks, two of which being identical with SRIH-28 and SRIH-14 while the other two likely represented precursor forms. Cortical SRIH content was not significantly affected by age. ChAT activity and SRIH content were not significantly correlated. Amyloid angiopathy was observed in every brain examined and the presence of cortical lesions analoguous to senile plaques observed in the oldest case only which did not demonstrate important alterations in ChAT and somatostatin levels.

Identification of amyloid beta protein in the brain of the small, short-lived lemurian primate Microcebus murinus.

The deposition of amyloid beta (A beta) protein in the brain has been demonstrated immunocytochemically in the small Lemurian primate Microcebus murinus. Both meningocerebral vascular deposits and cortical parenchymal deposits occur. All eight aged (> 8 years old) Microcebus examined showed vascular amyloid deposits, whereas only four exhibited parenchymal plaques. The vascular amyloid infiltrated the tunica media of the leptomeningeal and cortical arteries and arterioles and was also found in capillaries. A beta was observed to be deposited in three general forms in the cortical neuropil: round or elliptical plaques that were thioflavin-negative but sometimes showed a central concentration of A beta immunoreactivity; round plaques with a densely immunoreactive core that was thioflavin-positive; extensive ribbon-like infiltrations enclosing multiple cortical blood vessels. These observations, taken together with previous descriptions of age-related neurodegenerative changes in Microcebus, indicate that this species undergoes a beta-amyloid-associated neuropathology highly similar to that seen in Alzheimer's disease. We conclude that this lemurian primate of small size and relatively short life expectancy, provides a compelling animal model of some principal features of Alzheimer's disease.

[Similarities between cerebral amyloid plaques in aged lemurian and in human with Alzheimer's disease]. / Similitudes entre les plaques amyloïdes cérébrales d'un lémurien âgé et de l'homme atteint de maladie d'Alzheimer.

Microcebus cerebral cortex has been investigated using various technics: amyloid beta-A4 protein, alpha-1 antichymotrypsin and ubiquitin immunocytochemistry, thioflavin S staining for amyloid deposition and Bodian's silver impregnation not only for amyloid plaques but also for degenerated neurites; glial fibrillary acidic protein (GFAP) immunocytochemistry has been also used for astrocytes. Parenchymal beta-A4 amyloid is observed to be deposited in some aged Microcebus cerebral cortex in three forms: 1) diffuse plaques of about 100 microns in diameter; 2) dense plaques with compact amyloid core which are thioflavin-positive; these two types of amyloid plaques (AP) are also stained both with the antibodies against alpha 1-antichymotrypsin and ubiquitin respectively; they are also associated with GFAP-immunoreactive astrocytes; 3) extensive ribbon-like infiltrations enclosing multiple blood vessels. The distribution of the AP using an automatic image analyser has showed that the density of the AP in the neocortex fluctuates among the different cortical regions. The density is respectively up to 16 AP/mm2 in the superior part of the temporal lobe and 12 AP/mm2 in the amygdala, 9 AP/mm2 in the prefrontal area of the frontal lobe and 11 AP/mm2 in the central area, 10 AP/mm2 in the parietal lobe and 5 AP/mm2 in the occipital lobe. The compact AP are more often observed in the temporal lobe. In Alzheimer's disease the AP are also made of amyloid beta-A4 protein, alpha 1-antichymotrypsin and ubiquitin. As in Microcebus, in Alzheimer's disease two types of AP are observed: the diffuse and the compact AP; the latter are also thioflavin S positive. The dense AP are not so numerous as the diffuse AP and the density of the AP is greater in the temporal lobe. All these results lead to the conclusion that the AP occurred in age Microcebus brain are similar in many respects to those found in Alzheimer's disease. So, Microcebus murinus, lemurian primate of small size (about 100 g) and relatively short life span (up to 12 years), should provide a valid animal model for investigation of some principal features of Alzheimer's disease.

Systematisation of the olfactory bulb efferent projections in a lemurian primate: Microcebus murinus.

In order to investigate a sensorial pathway essential in animal behavior, the efferent projections of the olfactory bulbs in Microcebus murinus were identified after transection of one olfactory peduncle and revelation of degenerating fibers by various silver staining methods. Total and partial sections have enabled the demonstration of the involvement in the olfactory projection areas of each olfactory tract: the lateral olfactory tract (LOT) and the intermediate olfactory tract (IOT), either via the medial forebrain bundle (MFB) or not. The IOT fibers innervate the cortex, the anterior olfactory nucleus, the caudate-putamen, the septum and the hippocampus on both sides. The LOT fibers reach the olfactory tubercle, the piriform cortex, the entorhinal cortex and the amygdala on both sides. Olfactory fibers could also be observed in the MFB innervating on both sides firstly the hypothalamic areas (the lateral hypothalamus, the suprachiasmatic, posterior supraoptic, mammillary nuclei and the median eminence), and then the mesencephalic structures (the locus coeruleus and the raphe nuclei). It may be concluded that the olfactory bulbs are not only connected with above-mentioned telencephalic areas, but are also directly related to the vegetative and integrative brain areas located in the hypothalamus and the brainstem and especially with the major nuclei which play an essential role in neurovegetative, neuroendocrine and behavioral regulation.

Senile plaques and neurofibrillary changes in the brain of an aged lemurian primate, Microcebus murinus.

In some aged Microcebus brains (8- to 11-year-old animals) dramatic atrophy is found, particularly of the cortex, the hippocampus, the basal ganglia, the brainstem and the cerebellum, associated with a conspicuous increase in the size of the cerebral ventricles. These morphological changes are accompanied by certain histological profiles indicative of pathology. In the cortex, these histological changes consist of 1) a large number of senile plaques composed of degenerated neurites sometimes surrounding an amyloid plaque, 2) amyloid deposits in the vascular walls and 3) dense bundles of argyrophilic filaments in numerous pyramidal neurons. All these lesions resemble changes associated with Alzheimer's disease in man. The degenerative changes observed in the Microcebus brain are accompanied by behavioral changes. At the moment these preliminary studies, carried out on the smallest of all primates, do not prove that the degeneration is of the Alzheimer type, but do indicate that Microcebus murinus may well be a good model for the study of cerebral aging, providing a comparison with cerebral ageing in humans. The size, life span and cost of the animal provide further advantages when compared with other nonhuman primates.

[Presence of neuritic plaques and neurofibrillary changes in the cerebral cortex of an aged lemuride primate]. / Présence de plaques neuritiques et de modifications neurofibrillaires dans le cortex cérébral d'un primate lémurien âgé.

Some aged Microcebus murinus brains (8 to 11-years old animals) displayed a dramatic atrophy particularly in the neocortex, hippocampus, basal ganglia, hypothalamus, brainstem and cerebellum, associated with a conspicuous increase in the size of the cerebral ventricles. These morphological changes were accompanied by certain histological profiles indicative of pathology. In the cortex, these histological changes consisted of (1) a large number of neuritic plaques formed by degenerated neurites sometimes surrounding an amyloid plaque, (2) dense bundles of argyrophilic filaments in many pyramidal neurons, and (3) amyloid deposits in and around the vascular walls. So far these preliminary studies cannot prone that this degeneration is similar to the human senile dementia of Alzheimer's type, but they may indicate that Microcebus murinus may well be a good model to study cerebral aging, providing comparisons with humans. Furthermore, the size, life span and cost of this species provide further advantages over other nonhuman primates.

Localization and characterization of neuropeptide Y in the brain of Microcebus murinus (Primate, Lemurian).

The distribution of neuropeptide Y (NPY) in the brain of the lemur Microcebus murinus was determined by immunocytochemistry with the aid of a highly specific antiserum against synthetic porcine NPY. When compared with previous immunohistochemical data obtained in primates and other mammalian species, the localization of NPY-immunoreactive (IR) structures in the Microcebus murinus brain revealed particular features. (1) Numerous NPY-IR perikarya and a dense network of IR nerve terminals were found in the supraoptic and suprachiasmatic nuclei, respectively. The occurrence of NPY-IR perikarya in the supraoptic nucleus, also reported in the squirrel monkey, seems to be specific to primates. In the squirrel monkey, the suprachiasmatic nucleus exhibits only a moderate innervation, whereas in humans it appears totally devoid of NPY-IR fibers. (2) IR perikarya and axon processes were observed in many upper brainstem areas, in particular in the interpeduncular, raphe pontine, dorsal tegmental, parabrachial, and dorsal raphe nuclei, in the locus coeruleus, the nucleus of the solitary tract, and the reticular formation; in this latter area, the occurrence of two categories of NPY-IR neurons was demonstrated on the basis of their morphology and localization, suggesting that they may play distinct roles. (3) NPY-IR nerve processes could be traced over a long distance. (4) For the first time, numerous NPY-IR terminals were observed close to the lumen of the various cerebral ventricles. The immunoreactive NPY-like peptide was characterized by combining high performance liquid chromatography (HPLC) analysis and radioimmunoassay quantification. The dilution curves obtained with synthetic porcine NPY and serial dilutions of occipital cortex, paraventricular and supraoptic hypothalamus, posterior hypothalamus, medulla oblongata, or preoptic area extracts were parallel. The highest amounts of NPY were measured in the hypothalamus and telencephalon. HPLC analysis resolved a single peak of NPY-like immunoreactivity that exhibited the same retention time as synthetic porcine NPY. The distribution of NPY in the lemurian brain is discussed with respect to phylogeny and putative functions.

[Demonstration of direct olfactory projections in the hypothalamus, the mesencephalon and the metencephalon of Microcebus murinus (Primate, Lemurian)]. / Mise en évidence de projections olfactives directes dans l'hypothalamus, le mésencéphale et le métencéphale de Microcebus murinus (Primate, Lémurien).

The efferent projections of the olfactory bulb in Microcebus murinus were identified after transection of the olfactory peduncle and after the revelation of the degenerating fibers by different silver staining methods. Total and partial sections have allowed demonstrating the importance of the two olfactory tracts in the olfactory projection areas. Degenerated fibers and endings were evidence not only in the different telencephalic regions, as classically known, but also in various hypothalamic nuclei (lateral hypothalamus, the suprachiasmatic, posterior supraoptic and mammillary nuclei and in the median eminence) and in several mesencephalic and metencephalic nuclei (ventral tegmental area, interpeduncular and raphe nuclei, and locus coeruleus). In all these structures the degenerate fibers were seen on both sides. The olfactory projections appeared not to be limited to the telencephalic areas. Moreover, the olfactory bulbs seem to be directly connected especially with the vegetative and integrative areas localized in the hypothalamus and the brainstem and particularly with the major aminergic nuclei that play an essential role in the neurovegetative, neuroendocrine and behavioral regulations.