P. Geoffrey Moore

Physiological stress in decapod crustaceans (Munida rugosa and Liocarcinus depurator) discarded in the Clyde Nephrops fishery

Crustacean discards experience stress during commercial fishing operations, due to increased exercise while in the trawl and aerial exposure during sorting of the catch. Physiological stress and recovery were assessed following trawling of two ecologically important decapod species, regularly discarded in the Clyde Nephrops fishery. Haemolymph samples taken from trawled swimming crabs, Liocarcinus depurator, and squat lobsters, Munida rugosa, had significantly higher concentrations of ammonia (0.308 and 0.519 mmol l(-1)), D-glucose (0.14 and 0.097 mmol l(-1)) and L-lactate (6.2 and 0.87 mmol l(-1)) compared with controls, indicating an impairment of ammonia excretion and a switch to anaerobic metabolism. Concurrently, the haemolymph pH of trawled squat lobsters was low (7.47) compared with controls (7.75); however, the reverse trend was found in L. depurator. Initially elevated lactate (7.98 mmol l(-1)) and glucose (0.73 mmol l(-1)) concentrations of trawled and emersed (1 h) L. depurator were restored, 4 h after re-immersion along with pH (7.54). Crabs that had been emersed for 1 h had significantly higher concentrations of glucose (0.2 mmol l(-1)) and lactate (5.14 mmol l(-1)), and had more acidic blood (7.64) than L. depurator subject to 1 h of exercise, indicating that anoxia was the main cause of physiological stress. Crabs and squat lobsters lost 7% and 9% of their initial body wet weight following 1 h of emersion, although blood osmolarities did not change significantly. While all animals survived aerial exposure in our experiments, sorting of the catch on commercial boats takes up to 300 min, which could lead to mortality or sub-lethal chronic biochemical changes that could compromise fitness.

Substratum-mediated heart rate responses of an invertebrate to predation threat

Although the relation between behaviour and stress in humans and other vertebrates is well documented, few comparable observations exist for invertebrates. We addressed this issue by considering the impact of the physical environment on cardiac activity in invertebrates exposed to predation and nonpredation threat scenarios. We used cardiac activity as a proxy of stress in juvenile queen scallops, Aequipecten opercularis, under predation threat by the common starfish, Asterias rubens. Stress levels were monitored in juvenile queen scallops exposed, and not exposed, to predation threat on a substratum known to act as a refuge (live maerl) as well as substrata known not to possess refuge potential (dead maerl, sand and no sediment). In the vicinity of known refuges, stationary scallops under predation threat had significantly lower cardiac activity than individuals in habitats lacking refuges. Scallops not under predation threat did not show significant differences in cardiac activity. These are probably habitat-mediated physiological responses to the presence of a predator and possibly to the availability of suitable attachment substrata. These findings have implications in terms of behavioural physiology in invertebrates.

Spinning a Marine Silk for the Purpose of Tube-Building

ABSTRACT Amphipod silk is a fibrous, self-secreted, adhesive substance employed in tube-building by amphipod species within the Corophiidea, Ampeliscoidea and Aetiopedidea. In the present study we provide a detailed characterisation of a novel, marine-based silk production system situated in pereiopods 3 and 4 in the corophioid Crassicorophium bonellii and the aorid Lembos websteri. The silk material is a mixture of protein and mucopolysaccharides. Ultrastructural and histological analyses revealed that silk in both species is produced in several rosette-type glands, presumed to be of two different types. These glands are distributed among all limb articles apart from the coxa but mainly in the basis and merus of pereiopods 3 and 4. Secretion commences in the basis and a thread-like secretion product leaves the glandular pereiopod through a cuticular pore near the dactylar tip. The silks physical and chemical properties most likely change while moving through the dactylar duct, which subdivides into several small ductules and terminates in a spindle-shaped chamber. This chamber, which communicates with the exterior, may be considered a silk reservoir in which the silk appears fibrous. For the first time an independently evolved, marine arthropod silk processing and secretion system is described.

Pagurisaea schembrii gen. et sp.n. (Crustacea, Amphipoda) Associated with New Zealand Hermit Crabs, with Notes on lsaea elmhirsti Patience

A description is given of both male and female Pagurisaea schembrii gen. et sp.n. (Isaeidae) which inhabit the topmost whorls of shells occupied by the hermit crab Paguristes pilosus Milne‐Edwards off Otago, New Zealand. Notes are appended on the male of Isaea elmhirsti and novel features of gnathopods, uropods and telson illustrated.