Influence of feeding regime and temperature on development and settlement of oyster Ostrea edulis (Linnaeus, 1758) larvae

Under controlled conditions of food density and temperature, larval performances (ingestion, growth, survival and settlement success) of the flat oyster, Ostrea edulis, were investigated using a flow‐through rearing system. In the first experiment, oyster larvae were reared at five different phytoplankton densities (70, 500, 1500, 2500 and 3500 μm³ μL^?1: ≈1, 8, 25, 42 and 58 cells μL^?1 equivalent TCg), and in the second, larvae were grown at four different temperatures (15, 20, 25 and 30°C). Overall, larvae survived a wide range of food density and temperature, with high survival recorded at the end of the experiments. Microalgae concentration and temperature both impacted significantly larval development and settlement success. A mixed diet of Chaetoceros neogracile and Tisochrysis lutea (1:1 cell volume) maintained throughout the whole larval life at a concentration of 1500 μm³ μL^?1 allowed the best larval development of O. edulis at 25°C with high survival (98%), good growth (16 μm day^?1) and high settlement success (68%). In addition, optimum larval development (survival ≥97%; growth ≥17 μm day^?1) and settlement (≥78%) were achieved at 25 and 30°C, at microalgae concentrations of 1500 μm³ μL^?1. In contrast, temperature of 20°C led to lower development (≤10 μm day^?1) and weaker settlement (≤27%), whereas at 15°C, no settlement occurred. The design experiments allowed the estimation of the maximum surface‐area‐specific ingestion rate  = 120 ± 4 μm³ day^?1 μm^?2, the half saturation coefficient {X_K} = 537 ± 142 μm³ μL^?1 and the Arrhenius temperature T_A = 8355 K. This contribution put a tangible basis for a future O. edulis Dynamic Energy Budget (DEB) larval growth model.     

Hindcasting modelling for restoration and conservation planning: application to stream fish assemblages

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Showcasing the sovereignty of non‐self‐governing islands: New Caledonia

Since 1983, no non‐self‐governing island connected to a (neo‐) colonial European or American metropole has acquired full Westphalian sovereignty and these islands continue to operate within constitutional frameworks that connect them to these metropoles. Large majorities in referendums on several of these islands have rejected full sovereignty. This paper opens with a review of the essential elements of the concept of sovereignty in a historical and global context, before studying how sovereignty is unfolding in new forms in non‐self‐governing islands in the Pacific and the Caribbean. As a case study, an analysis is presented of how pro‐France (loyaliste) and pro‐independence (indépendantiste) parties in New Caledonia are negotiating sovereignty with France. Evidence is given of how these New Caledonian parties are creatively using classic Westphalian signifiers of sovereignty normally reserved for sovereign states such as flags, diplomatic representations and international treaties, while still negotiating New Caledonia's sovereignty with France. This suggests that in contrast to Westphalian sovereignty, a unique ‘Islandian’ concept of sovereignty is emerging. Islands that are not sovereign in a Westphalian sense can creatively disassemble and reassemble signifiers of Westphalian sovereignty to strengthen their continuous negotiations with their metropoles and their neighbours.     

Analysis of a commercial dimethyl‐sulfoxide‐stabilized frozen canine platelet concentrate by turbidimetric aggregometry

Objectives – To assess platelet function of a commercial dimethyl‐sulfoxide (DMSO)‐stabilized frozen platelet concentrate (PC) using turbidimetric aggregometry. Design – In vitro analysis. Setting – Research laboratory in a school of veterinary medicine. Animals – Five units of frozen PC in 6% DMSO were studied. Fresh platelet‐rich plasma (PRP), with and without 6% DMSO, from 6 healthy dogs were used as controls. Interventions – Turbidimetric platelet aggregation was measured after initiation of platelet aggregation by addition of adenosine diphosphate (ADP), collagen, or thrombin at concentrations of 30 μM, 20 μg/mL, and 0.5 U/mL, respectively. Measures were performed at thaw and repeated 2 hours after thaw for the frozen PC. Measurements and Main Results – Compared with PRP, the frozen PC showed decreased aggregation in response to thrombin (amplitude of 84% versus 25%, P=0.01), and collagen (amplitude of 13% versus 3%, P=0.05) but not ADP (6.5% versus 18%, P=0.2). Compared with frozen PC at thaw, the frozen PC at 2 hours after thaw showed decreased aggregation in response to thrombin, collagen, and ADP (P<0.05). There was no difference in aggregation between PRP in 6% DMSO and frozen PC. Conclusions – These in vitro data suggest there is a decrease in platelet response to agonists associated with the freeze‐thaw process in the commercially available 6% DMSO canine frozen PC.     

Dispersal strategies of juvenile pike (Esox lucius L.): Influences and consequences for body size,somatic growth and trophic position

Individual variability in dispersal strategies, where some individuals disperse and others remain resident, is a common phenomenon across many species. Despite its important ecological consequences, the mechanisms and individual consequences of dispersal remain poorly understood. Here, riverine Northern pike (Esox lucius) juveniles (age 0+ (young-of-the-year) and 1+ years) were used to investigate the influence of body size and trophic position (at capture) on the dispersal from off-channel natal habitats and the subsequent consequences for body sizes, specific growth rate and trophic position (at recapture). Individuals that dispersed into the river (“dispersers”) were not significantly different in body size than those remaining on nursery grounds (“stayers”). For trophic position, 0+ dispersers were of significantly lower trophic position than stayers, but with this not apparent in the 1+ fish. Following dispersal into the river, the dispersers grew significantly faster than stayers and, on recapture, were significantly larger, but with no significant differences in their final trophic positions. Early dispersal into the river was, therefore, not associated with early dietary shifts to piscivory and the attainment of larger body sizes of individuals whilst in their natal habitats, contrary to prediction. These results suggest that despite an increasing risk of mortality for individuals dispersing early from natal areas, there are long-term benefits via elevated growth rates and, potentially, higher fitness. Such early dispersal behaviour could be driven by early competitive displacement.     

Red operculum spots,body size,maturation and evidence for a satellite male phenotype in non‐native European populations of pumpkinseed Lepomis gibbosus

Carotenoid‐based pigmentation is a striking feature of many taxa, yet the function, if any, of colour traits is often unclear. Pumpkinseed Lepomis gibbosus, a widely introduced freshwater sunfish that exhibits alternative male mating strategies, express a striking, red operculum spot. To investigate the potential function of this red spot as a signal in this species' mating system, we determined the presence and measured the size of red operculum spots in fish collected from 12 populations in five European countries in which pumpkinseed is an established non‐native species. We subsequently related the presence and size of the red spot to body size and mating strategy, based on an analysis of relative gonad size (gonado‐somatic index, GSI), using a mixed modelling approach. The study demonstrated that the presence of a red operculum spot in pumpkinseed is associated with sexual maturation, with GSI frequency distributions suggesting that cuckolders in some non‐native populations comprised both sneaker and satellite males, the latter not having previously been reported for this species. Further, the size of red spot correlated strongly with body size in parental and cuckolder males, although there was no difference in the presence or size of the red operculum spot between male mating strategies. The function of a red operculum spot in females is not clear but may be partly mediated by pleiotropic genetic mechanisms. Red operculum spots appear to function as signals of male maturation and body size in pumpkinseed, irrespective of mating strategy.     

Influence of postruminal supplementation of methionine and lysine, isoleucine, or all three amino acids on intake and chewing behavior, ruminal fermentation, and milk and milk component production.

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Political borders impact associations between habitat suitability predictions and resource availability

Landscape Ecology - By linking species of conservation concern to their abiotic and biotic requirements, habitat suitability models (HSM) can assist targeted conservation measures. Yet,...