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To assess whether giant scallops, Placopecten magellanicus use distinct escape strategies to respond to their seastar and crustacean predators, escape responses to two major seastar predators, Asterias vulgaris and Leptasterias polaris, two seastars with little predatory impact, Crossaster papposus and Solaster endeca, and two crustacean predators, Cancer irroratus and Hyas araneus were compared. A glass rod served as a mechanical control. The responses of juvenile [2+ year (y), ~36-mm shell height (SH)] and adult (6+ y, ~100-mm SH) scallops from the Magdalen Islands, Quebec, Canada, were assessed in early summer 2005. The predatory seastars evoked the strongest response, in terms of both response latency and minimum interval between phasic contractions and numbers of phasic contractions, particularly early in the escape response. Both the minor seastar predators and crabs stimulated stronger responses than the mechanical control. Juvenile scallops were livelier than adult scallops. As P. magellanicus consistently responded to predators with an initial flurry of phasic contractions that tapered off to spaced phasic contractions separated by increasingly long tonic contractions, only the intensity of the escape response seems to have been modified by selection.

Abstract Supplying juvenile sea urchins with an abundant supply of resources and essential nutrients for growth will facilitate somatic growth and, hence, improve the success of the sea urchin aquaculture industry. Lipids are essential in physical processes such as membrane production and are a concentrated source of energy. This study, using prepared diets, tested the effects of lipid sources containing different major fatty acids (i.e., n‐3 and/or n‐6) (Part 1) and lipid concentration (i.e., 1, 3, 7, and 10%) (Part 2) on the somatic (i.e., test or shell) growth of two size cohorts (7.0‐ and 15.3‐mm average initial test diameter [TD]) of juvenile green sea urchins, Strongylocentrotus droebachiensis. The growth of the sea urchins fed prepared diets was compared to the growth of sea urchins fed a kelp reference diet, Laminaria longicruris. After both feeding trials, the kelp‐fed sea urchins had superior test growth and were more similar in physical appearance to wild sea urchins (i.e., test color, spine length, and gonad color). The sea urchins fed the prepared diets had pale test color, short, stubby spines, and large, pale‐colored gonads compared to wild sea urchins. The smaller cohort of sea urchins grew at a faster rate, but growth patterns for both cohorts were similar. The juveniles fed the prepared diets (in both feeding trials) had high initial growth rates that decreased after approximately 100 d compared to the kelp‐fed juveniles. Differences in test growth were not shown to be affected by sea urchin size (i.e., similar results for both cohorts) or by differences in dietary lipid sources (i.e., the presence of n‐3 and/or n‐6 fatty acids). However, the sea urchins fed diets with lower lipid concentration (≤3%) had larger average TDs than those fed diets with higher lipid concentrations (≥7%). Differences in test growth and physical appearance among those fed the prepared diets and kelp may have been because of nutritional deficiencies in the prepared diets.

Duplisea, D. E. 2005. Running the gauntlet: the predation environment of small fish in the northern Gulf of St Lawrence, Canada. e ICES Journal of Marine Science, 62: 412e416. Predation size spectra were constructed for the northern Gulf of St Lawrence, covering prey size ranges that include pre-recruit cod. Predation by fish and harp seals was modelled with a log-normally distributed predatoreprey size ratio along with a relationship between predator body size and the energy required. Fish concentrate predation on prey of weight 0.5e2 g, whereas harp seals prefer prey of 60e125 g. It is speculated that predation caused by harp seals on pre-recruits could be a major factor limiting cod recruitment in the system. The northern Gulf of St Lawrence is a cold boreal system with a large predatory seal population, and cod recruit older than elsewhere. Therefore, cod recruitment may be more strongly affected by predation in the northern Gulf of St Lawrence than in warmer systems such as the North Sea, where recruitment is strongly influenced by temperature.

Fish are one of North America’s most valuable renewable resources. Although recreational anglers harvest a portion of their catch, modern recreational fisheries are based on the principle of sustainable use, and most are highly regulated using the best available science, fisheries data and risk assessments. Recent surveys indicate that approximately 10–20% of the North American population participates in angling, and the resulting economic impact is greater than that from commercial fishing and aquaculture; it even exceeds the combined annual revenue from several of the top major league sports in North America. The relationship between man and certain fish species that arises through activities such as recreational angling is an important driver of the science on aquatic species and their ecosystems. There are many other ways that recreational anglers contribute to conservation, with benefits for sportfish and non-sportfish species alike, as well as for North America’s aquatic ecosystems.

ABSTRACT This study determined the growth and biochemical composition of blue mussels (Mytilus edulis) reared on effluent from Atlantic cod (Gadus morhua) and compared it with mussels reared on a standard shellfish diet. Feeding trials lasted 6 mo, and mussels were sampled on a monthly basis. Dry weight, ash-free dry weight, shell length, and condition index were all significantly higher in algae-fed mussels at the end of the experiment compared with effluent-fed mussels. The carbon content decreased for mussels fed both diets; however, their nitrogen and protein content increased, with effluent-fed mussels having significantly more nitrogen and protein than algae-fed mussels, suggesting that effluent can increase mussel growth. Total lipid and fatty acid (FA) content decreased for effluent-fed mussels at the end of the experiment. There were no significant differences in the lipid class composition between mussels fed the 2 diets. Mussels fed both diets significantly decreased in the amount of 14:0, 16:1...

Abstract In vitro ruminal fermentation of ground and dry-rolled barley samples differing in starch content was evaluated using a batch culture technique. The study was arranged in a 2 (low and high starch) × 2 (ground and dry-rolled) factorial design. Gas production (GP), short chain fatty acids (SCFA), dry matter (DM) and starch disappearance were estimated at 3, 6, 12 and 24 h of incubation using rumen fluid from 3 ruminally fistulated beef cattle. Rate of GP was greater (P a + b (1 − e − c ( t − L ) ). Starch content × processing interactions were noted for the b fraction and rate of DM disappearance. Consistently, both high starch and ground barley samples had greater (P a and b fractions, rate constant of disappearance of b fraction and effective degradability versus low starch and dry-rolled samples. Expectedly, molar proportions of individual and total SCFA were greater (P versus low) had significant effect on the rate of GP and constant rate of DM disappearance but no effect on the constant rate of starch disappearance.

To broaden our knowledge about the toxicity of metals in marine elasmobranchs, cannulated spiny dogfish (Squalus acanthias) were exposed to 20 μM and 100 μM lead (Pb). Since we wanted to focus on sub lethal ion-osmoregulatory and respiratory disturbances, arterial blood samples were analysed for pH(a), PaO(2), haematocrit and total CO(2) values at several time points. Plasma was used to determine urea, TMAO, lactate and ion concentrations. After 96 h, Pb concentrations were determined in a number of tissues, such as gill, rectal gland, skin and liver. To further investigate ion and osmoregulation, Na(+)/K(+)-ATPase activities in gill and rectal gland were analysed as well as rates of ammonia and urea excretion. Additionally, we studied the energy reserves in muscle and liver. Pb strongly accumulated in gills and especially in skin. Lower accumulation rates occurred in gut, kidney and rectal gland. A clear disturbance in acid-base status was observed after one day of exposure indicating a transient period of hyperventilation. The increase in pH(a) was temporary at 20 μM, but persisted at 100 μM. After 2 days, plasma Na and Cl concentrations were reduced compared to controls at 100 μM Pb and urea excretion rates were elevated. Pb caused impaired Na(+)/K(+)-ATPase activity in gills, but not in rectal gland. We conclude that spiny dogfish experienced relatively low ion-osmoregulatory and respiratory distress when exposed to lead, particularly when compared to effects of other metals such as silver. These elasmobranchs appear to be able to minimize the disturbance and maintain physiological homeostasis during an acute Pb exposure.

The BMJ ’s issue highlighting clinical and research malpractice is welcome,1 as is the recognition of trenchant resistance to change. Privileged groups seek to defend the indefensible.2 There is much privilege and profit to defend in health, including for health professional associations, corporations, and universities. Once qualified, clinical professionals find …