Influence of Hydrocarbons Exposure on Survival, Growth and Condition of Juvenile Flatfish

Juveniles of numerous commercial marine flatfish species use coastal and estuarine habitats as nurseries. Hence, they are likely to be exposed to a number of anthropogenic stressors such as accidental and chronic exposure to chemical contaminants. Little is known about their response to such pollutants at the individual level and about the consequences on their population dynamics. Mesocosm experiments were conducted to determine whether short (24 h) but high exposure to petroleum hydrocarbons (1/1000 v: v water: fuel), similar to what happened after an oil spill on coastal areas, af fects survival and biological (growth, body condition and lipid reserve) performances of juvenile common sole, which live on near shore and estuarine nursery grounds. Results demonstrated that this type of exposure significantly reduce survival, growth (size, recent otolith increment and body condition), and especially ener gy storage (triacylglycerol to free sterol ratio) of the juvenile fish on the medium-term (three months after the exposure).These medium-term consequences affect future recruitment of this long- lived species

Placing Joseph Banks in the North Pacific

The South Pacific was a fulcrum of Joseph Banks's maritime world and global networks. The North Pacific was a distance and intangible fringe. This article is concerned with how Banks should be ‘placed’ in the North Pacific. It tracks how Banks's activities have been delineated in terms of languages and categories of global and local, and centre and margin, and then considers the historical and geographical specifics apposite to his connection to the North Pacific. In this setting, ideas of place (as location and assignment) and capital (as a circulatory and everyday practice of exchange and opportunism) come into view and question the distinction between science and commerce in Banks historiography. The article considers a diverse group of non-Indigenous figures – explorers, traders, cartographers, scientists, collectors – operating in the North Pacific in the 1780s and 1790s whose initiatives and missives passed across Banks's desk, and assesses their place in Banks's archive by drawing on Peter Sloterdijk's ideas about the interiorising and exteriorising logic of capital.PostprintPeer reviewe

Goldmining and its effects on landscapes of the Cariboo

Bibliography: p. 170-178.The cultural process of gold mining is examined within the context of an area which has been subject to continuous gold mining for over a century, the Barkerville area of British Columbia. The physical background of this area and its position in the general history of gold mining are reviewed. The gold mining of the Barkerville area is considered under three time periods, delimited on the bas is of the predominant form of the mining technology employed. Thus the three periods are "the early period," "the hydraulic period," and "the lode mining period." The extent of mining, the form of its technology, the role of the government, t he organisation of the industry, and the effects of the mining on the landscape, are traced for each period. The landscape effects, under the headings of geomorphology, communications and settlements, and vegetation are mapped whenever possible. A comparative assessment of the effects of the various mining techniques is made: hydraulic mining producing the greatest landscape devastation. The recent introduction of a new land use, recreation, into the Barkerville area is considered in the light of its relationship to past gold mining. Current and possible future land use conflicts arising from this new development are indicated and recommendations made for handling them

Effects of water viscosity upon ventilation and metabolism of a flatfish, the common sole Solea solea (L.)

International audienceThe French Atlantic coast contains large highly productive intertidal mudflats that are colonised by juveniles of numerous flatfish species, including the common sole (Solea solea, L.). These ecosystems are also heavily exploited by the shellfish farming industry. Intensive bivalve culture is associated with substantial biodeposition (1–6 t-dw ha−1 day−1), which directly or indirectly contributes to increase exopolysaccharide (EPS) concentrations at the interface between water column and seabed. EPS are long-chain molecules organised into colloids, which influence rheological properties of water, particularly viscosity. Increased water viscosity had consequences for ventilatory activity of juvenile flatfish, whereby the minimal pressure required to ventilate the medium increases directly with EPS concentration. Moreover, the critical EPS concentration ([EPS]crit) at which water was no longer able to flow through the branchial basket ranged from almost nil to over 30 mg l−1, depending on species and size. [EPS]crit was lower in small individuals and individuals from species with high metabolic rates (turbot and plaice). These differences may depend upon gill and bucco-branchial cavity morphometrics. The ventilatory workload of sole increased with viscosity to a maximum at 2 mg EPS l−1. Viscosity might, therefore, be a limiting factor for flatfish post larvae, which colonise the intertidal mudflats, depending upon their size and species. EPS concentrations in the field can reach 15 mg l−1. A selective effect is conceivable but remains to be estimated in the field

Carbohydrate production in relation to microphytobenthic biofilm development: an integrated approach in a tidal mesocosm

International audienceExperiments were performed to evaluate short-term changes in sediment extracellular carbohydratesfor a multispecific assemblage of benthic diatoms in relation to physiological status,endogenous migratory rhythms, and environmental conditions. For this purpose, a mesocosmwas used, which simulated both tidal and dark: light alternating cycles under controlled conditions.Scanning electronic microscopy in combination with picture analyses indicated thatnatural diatom migration patterns were reproduced in the mesocosm. Two EPS fractions wereoperationally separated in colloidal carbohydrate measurements: alcohol-soluble EPS (termed‘‘soluble EPS’’) and alcohol-insoluble EPS (termed ‘‘bound EPS’’). Microphytobenthic biomassfollowed a logistic-type curve and converged toward a maximal value termed the ‘‘biotic capacityof the local environment.’’ Both EPS fractions showed oscillations with production duringphotosynthetic periods and sharp decreases during night immersion periods. Productions ofboth EPS fractions increased with Chl a production during light periods suggesting a lightdependence in relation to migratory patterns. The decreases in both EPS fractions, which occurredduring night immersion periods suggest that carbohydrate hydrolysis and/or washawayaffected both EPS fractions similarly in benthic environments. Our results confirm the theoryaccording to which the two distinct fractions are under different metabolic controls. No changein soluble EPS release was obtained during the transition from logarithmic to stationary phase.On the other hand, a metabolism modification of microalgae, probably related to ammoniumdepletion, occurred when cells entered the stationary phase, since there was a high enhancementin bound EPS production. Mesocosm results can serve as a system of reference useful to characterizebiofilm development in field investigations and to revisit the effective implication ofeach EPS fraction in sediment stabilit

Cost of living dictates what whales, dolphins and porpoises eat: the importance of prey quality on predator foraging strategies.

Understanding the mechanisms that drive prey selection is a major challenge in foraging ecology. Most studies of foraging strategies have focused on behavioural costs, and have generally failed to recognize that differences in the quality of prey may be as important to predators as the costs of acquisition. Here, we tested whether there is a relationship between the quality of diets (kJ · g(-1)) consumed by cetaceans in the North Atlantic and their metabolic costs of living as estimated by indicators of muscle performance (mitochondrial density, n = 60, and lipid content, n = 37). We found that the cost of living of 11 cetacean species is tightly coupled with the quality of prey they consume. This relationship between diet quality and cost of living appears to be independent of phylogeny and body size, and runs counter to predictions that stem from the well-known scaling relationships between mass and metabolic rates. Our finding suggests that the quality of prey rather than the sheer quantity of food is a major determinant of foraging strategies employed by predators to meet their specific energy requirements. This predator-specific dependence on food quality appears to reflect the evolution of ecological strategies at a species level, and has implications for risk assessment associated with the consequences of changing the quality and quantities of prey available to top predators in marine ecosystems