Sensitivity to stress of the estuarine bivalve Macoma balthica from areas between the Netherlands and its southern limits (Gironde)

Variation in the sensitivity to stress of Macoma balthica was measured in several French and Dutch estuaries. For adult and juvenile Macoma balthica exposed to copper under conditions of starvation, differences in mortality rate, condition, glycogen, burrowing rate and copper content were assessed. No significant differences were observed between adults and juveniles; the influence of treatment and origin was always evident. Animals from the most southern estuaries, Loire and Gironde, near to the species's southern limit of distribution, showed, in the field, the strongest deviations for the ecophysiological traits measured, and were in the experiments the most sensitive to stress.     

Observations on the Burrows and Burrowing Behaviour of the Red Band-Fish, Cepola rubescens L.

Abstract. The red band-fish, Cepola rubescens L., lives in burrows in sublittoral muddy sediments. The authors first presented information on the burrows of this species in the 1970s. The present paper presents new information on burrow structure, describes the method of excavation, and comments on the bioturbatory significance of the species. The work derives from field and laboratory studies. A burrow typically consists of a vertical shaft which opens into an expanded terminal chamber. In some cases a side shaft may be added. The paper includes a size analysis of 130 burrows measured in the field and detailed morphological information from a selection of burrows which were cast with polyester resin. The fish burrows are frequently intersected by the burrows of other species and interspecific associations may develop. Burrow size reflects the size of the occupant and may approach 1 m in depth. The biogenic movement of water and particles to this depth is often overlooked in bioturbation studies and is discussed. Burrow distribution is aggregate, which has implications for the bioturbatory impact of the species. Burrows are constructed by mouth excavation and this is described in detail. Fish transport fine material within their mouths and coarse material is grasped in the jaws. Large spoil heaps occur at burrow openings. One obvious effect of this bioturbatory activity at the field site was the redistribution of coarse material (shell gravel) from depth to the sediment surface.     

Seagrass as the main food source of Neaxius acanthus (Thalassinidea: Strahlaxiidae), its burrow associates, and of Corallianassa coutierei (Thalassinidea: Callianassidae)

Burrows of the thalassinidean shrimps Neaxius acanthus and Corallianassa coutierei are striking aspects in tropical seagrass beds of the Spermonde Archipelago, Indonesia. Burrow construction, behaviour, burrow type and associated commensal community were investigated to clarify the ecological role and food requirements of these shrimps and their commensals. Gut content analysis and stable-isotope data were used to unravel the food sources and the trophic interactions among the commensal community.Individuals of Neaxius acanthus were caught on Bone Batang Island. In narrow aquaria filled with sediment they constructed burrows resembling those found in the field. During burrow construction and maintenance only little sediment was brought to the surface, most was sorted and compacted to create a distinct lining. Maintenance work by single shrimps typically took about 5 min, after which the shrimp walked up to the entrance and rested for a similar period of time. There were no differences in behaviour between day and night. Intrasexual encounters inside the burrow were characterised by a high level of aggression and all resulted in one participant being driven out of the burrow. Intersexual encounters led to coexistence with both animals taking turns in burrow maintenance and guarding the entrance. Offered seagrass leaves were pulled underground, cut into pieces and eventually integrated into the lining. Burrows of Corallianassa coutierei resembled a deep U-shape. Chambers branching off halfway down and at the deepest point contained seagrass fragments. All steep parts of the burrow were lined similar to burrows of N. acanthus.No commensals were found associated with Corallianassa coutierei. However, burrows of Neaxius acanthus in the field typically contained a pair of shrimps, up to 8 individuals of the commensal bivalve Barrimysia cumingii and large numbers of gammarid amphipods. Other animals found associated with the burrow were the goby Austrolethops wardi, a palaemonid shrimp species and two species of tube-building polychaetes, one of which was also found as an epibiont on N. acanthus.Stable-isotope and gut content analyses indicate that the diet of Neaxius acanthus, its commensal Austrolethops wardi, and Corallianassa coutierei is mainly derived from detrital seagrass leaves, with a potential contribution of sediment organic matter and seagrass epiphytes. In contrast the isotopic signature of Barrimysia cumingii suggests the presence of symbiotic sulphide metabolism bacteria. This study underlines that, besides their interactions with the surrounding ecosystem, thalassinid shrimp burrows play an important role as a sub-habitat with a unique associated fauna.     

Burrowing behaviour of the paddle crab Ovalipes catharus (White, 1843) (Brachyura: Portunidae)

The burrowing behaviour of Ovalipes catharus (White, 1843) is described and compared with that of some other burrowing crabs. O. catharus is a fast, back burrowing crab which makes temporary burrows in soft sand. The average time from initiation of burrowing to complete submergence was 6.5 s, there was no difference between males and females but burrowing time increased significantly with crab size. Similar morphological adaptations are required for burrowing and swimming: streamlined body shape, smooth lightly constructed exoskeleton, and flattened legs. O. catharus has a reversed respiratory current like O. guadulpensis but it differs in its burrowing behaviour. Compared to some other crabs, burrowing in O. catharus is rapid.     

中国蛤蜊Mactra chinensis Philippi稚贝运动行为学初步研究

为从行为学角度解释中国蛤蜊(Mactra chinensis Philippi)的跑滩现象, 研究了规格、温度对其跳跃行为以及底质、流速和周期性干露对其潜沙行为的影响。结果表明, 中国蛤蜊运动能力与其规格和水温有关, 3 mm稚贝不具备跳跃能力, 5 mm以上具备跳跃能力; 跳跃频率和高度随水温的升高呈上升趋势。中国蛤蜊稚贝潜沙比例均随时间推移逐渐上升; 各时间节点中国蛤蜊稚贝在细沙底质的潜沙比例最高, 中沙底质次之, 粗沙底质最低。施加微弱水流后, 中国蛤蜊稚贝潜沙速度和比例显著增加; 流速增大到一定程度后部分稚贝被水流冲走, 潜沙比例随之下降。周期性干露会导致中国蛤蜊稚贝从底质中爬出, 干露时间越长, 爬出比例越高。干露后的稚贝重新放置于海水中, 部分稚贝会在水面漂浮一段时间后再下落至水底, 漂浮比例随干露时间的增加而增加。本研究从行为学角度初步查明了中国蛤蜊跑滩现象, 为解决中国蛤蜊防跑滩问题提供了思路。     

Comparing traditional and modern methods of kākahi translocation: implications for ecological restoration

ABSTRACT

Handling methods are an important determinant of translocation success. In Aotearoa/New Zealand, tangata whenua traditionally used insulated kete to translocate aquatic animals to new environments as part of ahumoana tawhito (ancient aquaculture). In this study we investigated the influence of three transport methods (traditional [flax kete], modern [bucket], and a hybrid of the two [bucket with flax support structures]) on the short-term performance (burrowing speed) of kākahi (freshwater mussels). We also tested whether assisted release (planting kākahi in the substrate) resulted in enhanced burrowing speeds. Kākahi that were transported using the traditional method were slower to begin probing the substrate, but there was no difference in overall burrowing speed. We also found that assisted release resulted in faster burrowing speeds. We conclude that handling and release procedures can influence the short-term performance of translocated kākahi, and we recommend procedures for future translocation projects, including transporting animals in immersion vessels where practical, and planting them at the release site     

Behaviour of some New Zealand sea anemones and their molluscan and crustacean hosts

The sea anemones Calliactis conchicola Parry, 1952 and Paracalliactis rosea Hand, 1975, which live associated with gastropods, hermit crabs, and true crabs, possess mounting responses similar to those known for several species of Calliactis. In some areas of New Zealand Calliactis conchicola occurs most abundantly on living gastropods and in others on gastropod shells occupied by hermit crabs. No behaviour by either the gastropod or the hermit crabs was observed which explains this differential distribution. One hermit crab stimulates Paracalliactis rosea to mount its shell by a regular tapping of the anemone with its chelae or dactyls, but ignores Calliactis conchicola. Several other hermit crabs, which may be found carrying these anemones, do not stimulate them to mount. The spider crab Leptomithrax longipes may be found in nature carrying specimens of four kinds of anemones: Calliactis conchicola, Paracalliactis rosea, Bunodactis chrysobathys, and Phellia aucklandica. This crab prises these anemones from most substrates with its chelae, cleans them with its mouth parts, and places them on its legs and carapace with its chelae. From observation, Calliactis conchicola apparently protects this crab from octopus predatiori, but not from other predators such as small sharks. Though associations of anemones with hermit crabs and other invertebrates are usually considered to be commensal, it seems likely that these associations may be mutualistic.     

The Diel Behaviour of Small Demersal Fish on Soft Sediments on the West Coast of Scotland using a Variety of Techniques: with Special Reference to Lesueurigobius friesii (Pisces; Gobiidae)

Abstract. The diel behaviour of communities of small demersal fishes was studied in situ on the west coast of Scotland using trawling, diving, underwater television and underwater time-lapse photography techniques. Lumpenus lampretaeformis and Pomatoschistus norvegicus were shown to have crepuscular behaviour patterns. Lesueurigobius friesii was a day active fish, spending the night close to or within its burrow and feeding through the day. Disruptions to this behaviour pattern occurred at high abundances of gadoids and during the spawning season. The fish community as a whole showed a crepuscular periodicity. The various observational methods are discussed. There did not appear to be any close association between Lesueurigobius friesii and the decapod Nephrops norvegicus.