Ingestion of Plastic Microfibers by the Crab Carcinus maenas and Its Effect on Food Consumption and Energy Balance.

Green crab (Carcinus maenas) have recently invaded the southern Gulf of St. Lawrence, Canada. Although these invasive crabs have coexisted without appreciable impact on American lobster (Homarus americanus) populations in northeastern United States, Bay of Fundy, and the southern shore of Nova Scotia, Canada, the green crab in the southern Gulf of St. Lawrence likely represents a new introduction of crab from northern Europe. The southern gulf is ideal habitat for green crab, and the crab are commonly captured subtidally, increasing the potential for overlap with juvenile lobsters. To complement previous experiments with green crab versus small (28–57 mm carapace length, CL) and medium (55–70 mm CL) sized lobsters in food competition trials, this paper reports findings from trials with large (72–80 mm CL) lobsters. The lobsters were first to gain possession of the food in an equal number of trials as green crab. The large lobsters fed for 62% of the total feeding time, versus 38% for the green crab, and initiated a significantly greater number of aggressive interactions than green crab. It appears that a reversal of dominance with adult green crab occurs once lobsters exceed 72 mm CL.

Populations of green crab (Carcinus maenas) have expanded within Newfoundland, and this has raised concern from fish harvesters and scientists regarding bivalve predation in coastal areas on species such as juvenile sea scallops (Placopecten magellanicus). We used 2 microcosm experiments to determine (1) the effects of water temperature (5°C and 12°C) on scallop predation; (2) scallop size selection in small and large green crabs and a large indigenous predator, the rock crab (Cancer irroratus); and (3) bivalve prey selection in large green crabs between softshell clams (Mya arenaria), blue mussels (Mytilus edulis), and sea scallops. Overall, green and rock crabs captured 4 times more scallops in warm water (12°C) than cold (5°C). Large green (60–70 mm) and rock (75–90 mm) crabs captured similar numbers of scallops, selected medium-size (30–40 mm) scallops, and avoided small (10–20 mm) scallops. Small green crabs (40–50 mm) captured only small scallops. Large green crabs selected softshell clams ...

BackgroundThe parasitic dinoflagellates of the genus Hematodinium represent the causative agent of so-called bitter or pink crab disease in a broad range of shellfish taxa. Outbreaks of Hematodinium-associated disease can devastate local fishing and aquaculture efforts. The goal of our study was to examine the potential role of the common shore (green) crab Carcinus maenas as a reservoir for Hematodinium. Carcinus maenas is native to all shores of the UK and Ireland and the North East Atlantic but has been introduced to, and subsequently invaded waters of, the USA, South Africa and Australia. This species is notable for its capacity to harbour a range of micro- and macro-parasites, and therefore may act as a vector for disease transfer.MethodsOver a 12-month period, we interrogated 1191 crabs across two distinct locations (intertidal pier, semi-closed dock) in Swansea Bay (Wales, UK) for the presence and severity of Hematodinium in the haemolymph, gills, hepatopancreas and surrounding waters (eDNA) using PCR-based methods, haemolymph preparations and histopathology.ResultsOverall, 13.6% were Hematodinium-positive via PCR and confirmed via tissue examination. Only a small difference was observed between locations with 14.4% and 12.8% infected crabs in the Dock and Pier, respectively. Binomial logistic regression models revealed seasonality (P < 0.002) and sex (P < 0.001) to be significant factors in Hematodinium detection with peak infection recorded in spring (March to May). Male crabs overall were more likely to be infected. Phylogenetic analyses of the partial ITS and 18S rRNA gene regions of Hematodinium amplified from crabs determined the causative agent to be the host generalist Hematodinium sp., which blights several valuable crustaceans in the UK alone, including edible crabs (Cancer pagurus) and langoustines (Nephrops norvegicus).ConclusionsShore crabs were infected with the host generalist parasite Hematodinium sp. in each location tested, thereby enabling the parasite to persist in an environment shared with commercially important shellfish.

The competitive and predatory impacts of the nonindigenous crab Carcinus maenas (L.) on early benthic phase Dungeness crab Cancer magister Dana.

ABSTRACTThe growth and spread of non-indigenous green crabs (Carcinus maenas) in Atlantic Canada is of concern to the sustainability of shellfish resources, particularly in areas recently invaded. Commercial green crab fishing has been initiated on Prince Edward Island to help control this species and provide a new resource for inshore fishermen. Developing a soft-shell crab product modelled after the Venetian ‘Moleche’ would provide an economic incentive beyond the existing hard-shell crab bait market. However, answers to questions such as the timing and characteristics of green crab moulting are required. A pilot study conducted in 2014–2015 collected seven groups of crabs and held them in individual compartments for 2–4 weeks to record moulting rates and physical characteristics. We found that a synchronized ‘moulting window’ occurs during July for male crabs. Field experiments in 2015 had an average moulting rate of 34%, with group-specific rates as high as 60%. The same cohort of crabs held in the laboratory had an average moulting rate of 48%, with group-specific rates as high as 75%. We observed a gradual increase in moulting rates from early to mid-July, after which all crabs caught had recently moulted, with evidence of new carapaces on all crabs. In 2015, the moulting window followed a 5°C increase in water temperature. Regarding morphology, the presence of a ‘halo’ on the episternites of the carapace was an indicator that a crab would soon moult. These promising results represent the first step in assessing the feasibility of a soft-shell, green crab industry.

Scavengers are common in marine environments and provide an essential ecosystem service, helping to return nutrients and energy contained in carrion to the system. Knowledge of the prevalence of scavenging is required to fully understand marine food webs. As most scavengers are also predators it is usually unclear what proportion of their diet is derived from carrion, and if this proportion varies in time. In this study we set out to determine whether the input of seabird or other carrion could be detected in the stable isotope composition of the shore crab (Carcinus maenas). Shore crabs were captured in the intertidal zone of the Isle of May (Scotland) before and after the peak fledging of Atlantic puffins (Fratercula arctica). The stable isotope (δ15N and δ13C) compositions of crabs and the proposed carrion source were determined. Fifty crabs were selected (25 from before (IOM1) and 25 after the fledging period (IOM2)). IOM1 had a mean δ15N value of +13.85‰ and IOM2 a mean of +13.53‰. The mean δ13C values were –15.46‰ for IOM1 and –15.87‰ for IOM2. In contrast to our expectations, there was no evidence that shore crabs were feeding on seabird carrion following the post-fledging period of Atlantic puffins. Future sampling in autumn months following the grey seal (Halichoerus grypus) breeding season may be useful in establishing if there is another route for nutrient and energy cycling between higher predators and marine scavengers at this location.

Mussels are found in two quite different kinds of habitat between tide marks: open coast, and very sheltered places such as harbours and estuaries. This is true also of the Lough Ine area (Ebling, Kitching, Sleigh & Sloane, in press). Here the open sea Mytilus are all rather small, whereas those in shelter at the north end of the lough and in the Goleen include many large ones. Mytilus is present both in the straight (M. edulis) and hooked (M. galloprovincialis) forms (Hepper 1957) and both are present in both types of habitat (Ebling et al., in press). We have also seen Mytilus in a third kind of habitat at Lough Ine, sublittorally in strong current on the Sill. It is possible that the discontinuous distribution of Mytilus in the Lough Ine area is due to predation. On this hypothesis the predators would be affected adversely by wave action, by strong current, and also by some condition (possibly low salinity) operating in those parts of the lough least affected by tidal exchange. Mytilus would also benefit by situations where it was less accessible, such as deep crevices and vertical rock faces. The predacious gastropod Nucella lapillust is abundant on the dense beds of small Mytilus at open sea stations and is also found on sublittoral Mytilus on the Sill. Other possible predators of established mussels include the crabs Cancer pfagurus, Xantho incisus, Carcinus maenas and Portunits puber, and the starfishes Asterias rubens, Marthasterias glacialis and Asterina gibbosa, all common in the lough. The sea urchin Paracentrotus lividuts is abundant in the lough, and Echinus esculentus is not infrequent from the Bullock Narrows to the south-east corner of the lough. Of these Echinus is known to include animal material in its diet. Many other predators may affect the younger stages, so that the problem is likely to be complicated. We have so far confined our attention to Mytilus of the range of sizes found at Carrigathorna on the open coast (up to 25 mm in length) and at the north end of the lough (mainly 30-70 mm). Preliminary samples suggest that the small Mytilus found at Carrigathorna are almost entirely M. edulis and the large ones at the north end of the lough mainly M. galloprovincialis, but further investigations will be needed before we can report definitely on the distribution of these two forms or comment on their validity as species.

Local knowledge is making important contributions to environmental management. Improving understanding of local knowledge that is in the early stages of development may be useful towards management of novel species or understanding other contemporary events. In this study we interviewed Nova Scotian fishermen with experience with a recently arrived invasive species, the European green crab (Carcinus maenas), to evaluate their knowledge of its local distribution. Ten participants who had either fished green crab or experienced it as a by-catch were interviewed. Environmental, temporal and internal population factors that were frequently associated with green crab distributions were reported by participants. Environmental factors described included primarily depth, vegetation, biotic interactions and bottom type. Furthermore, interactions with temporal factors (e.g. tidal and seasonal changes) as well as internal-population factors (e.g. sex and age) were observed by a number of participants. Internal factors were described more frequently among participants with more experience and more direct associations with green crab. Local knowledge illustrates not only a nascent understanding of this species’ distribution, but realization of internal population structure and temporal variations, which may help to refine management strategies. This study illustrates the potential for local knowledge to form and develop, even around relatively recent environmental events.

The coastal and marine environment performs several key functions—regulating the climate, sequestering carbon dioxide, and sustaining essential biological processes. With close to a quarter of the world’s population living in coastal and adjacent areas and millions depending on coastal and marine ecosystems and resources for their livelihood and sustenance, the health of the marine and coastal environment is critical. Despite this, the coastal and marine environment is fast deteriorating, the degradation set to accelerate rapidly with climate change and sea level rise. This chapter provides an understanding of these developments and the current state of the law on the protection of the marine and coastal environment in India evaluating its capacity to respond to these challenges. In this regard, the focus will be on India’s coastal law and the attempts to operationalize integrated coastal zone management which has global recognition as the primary pathway to secure sustainable coastal development.

An increasing number of examples suggest that interactions among introduced species are ecologically important and relevant to the management of invaded systems. We investigated the potential for the introduced cephalaspidean sea slug Philine orientalis to interfere with the feeding of the introduced European green crab (Carcinus maenas) and the native Dungeness crab (Cancer magister). We observed co-occurrence of crab species and P. orientalis at field sites in Bodega Harbor and Tomales, San Pablo, and San Francisco Bays. In laboratory and field experiments, we determined whether crab feeding was suppressed by P. orientalis and the duration of this suppression for individual crabs. We also used foraging response models to explore changes in the feeding rate of crabs with varying densities of P. orientalis and small bivalve prey. We found that P. orientalis deterred predation by green and Dungeness crabs on small clams in laboratory feeding trials, but not in field experiments with green crabs and P. orientalis. Foraging models predicted that P. orientalis would only affect crab feeding in the field under specific conditions of crab, P. orientalis, and prey densities. These foraging models bridged an important gap between lab and field experiments and allowed us to predict how changes in species abundances at two trophic levels might alter the importance of crab suppression by P. orientalis.

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 187:237-250 (1999) - doi:10.3354/meps187237 Foraging by mobile predators on a rocky shore: underwater TV observations of movements of blennies Lipophrys pholis and crabs Carcinus maenas Michael T. Burrows1,*, Kei Kawai2 , Roger N. Hughes2 1Dunstaffnage Marine Laboratory, Centre for Coastal Marine Sciences, PO Box 3, Oban PA34 4AD, United Kingdom 2School of Animal Biology, University of Wales, Bangor LL57 2UW, United Kingdom *E-mail: mtb@wpo.nerc.ac.uk ABSTRACT: The hypothesis was proposed that shore fishes and crabs, predators other than gastropods, may be primarily responsible for depletion of barnacle populations in the vicinity of crevices through thigmotactic behaviour during foraging. To test this hypothesis, movements of mobile predators on barnacle-dominated rock in the lower intertidal zone were observed using a fixed underwater television camera. An area of 0.2 m2 was monitored continuously for 14 d on a vertically oriented but relatively protected shore on the west coast of Scotland. Infrared lights during nighttime high tides lit the area. Stereo photography was used to determine the topography of the area. The principal species seen by day was the blenny Lipophrys pholis (L.) while the shore crab Carcinus maenas (L.) was the most frequent species at night. Scorpion fish Taurulus bubalis (Euphrasen), dogwhelks Nucella lapillus (L.) and a single North American mink Mustela vison Schreber were also seen. Movements of crabs, and especially blennies, were concentrated around small-scale concavities in the rock surface of less than 10 cm dimensions, supporting the primary hypothesis. Times spent by Lipophrys pholis and Carcinus maenas in 0.001 m2 (10 cm2) areas within the video frame varied by 3 and 2 orders of magnitude, respectively. These 2 species are known to be active predators of barnacles Semibalanus balanoides and showed behaviour consistent with attacks on barnacles as prey. Observed movements and apparent spatial concentration of attacks, especially around crevices, may be a cause of patchiness in barnacle populations at this scale. KEY WORDS: Rocky shores · Predation · Barnacles · Crabs · Intertidal fishes · Surface topography Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 187. Publication date: October 14, 1999 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1999 Inter-Research.

The Shore Crab (Carcinus maenas) is an excellent subject for school study, both in the field and the laboratory. It is easily collected and maintained and can be used for a wide range of investigations. Some background details are given and possible areas of investigation suggested.

The major objective of this study was to determine whether there were significant differences in the physiological responses of shore crabs (Carcinus maenas L.) sampled from environments with varying degrees of contamination. Crabs collected from a range of sites were subjected to a standardised, environmentally realistic sequence of physiological challenges in the laboratory to determine if such measures would prove sensitive enough to differentiate among the sites. Heart-rate changes and osmoregulatory ability were measured. The results indicated that changes in osmoregulatory ability were sufficiently sensitive to detect differences in environmental contamination. The utility of physiological measurements in environmental monitoring is discussed.

Worldwide growth of offshore renewable energy production will provide marine organisms with new hard substrate for colonization in terms of artificial reefs. The artificial reef effect is important when planning offshore installations since it can create habitat enhancement. Wind power is the most advanced technology within offshore renewable energy sources and there is an urgent need to study its impacts on the marine environment. To test the hypothesis that offshore wind power increases the abundance of reef species relative to a reference area, we conduct an experiment on the model species common shore crab (Carcinus maenas).Overall, 3962 crabs were captured, observed, marked and released in 2011 and 1995 crabs in 2012. Additionally, carapace size, sex distribution, color morphs and body condition was recorded from captured crabs. We observed very low recapture rates at all sites during both years which made evaluating differences in population sizes very difficult. However, we were able to estimate population densities from the capture record for all three sites. There was no obvious artificial reef effect in the Lillgrund wind farm, but a spill-over effect to nearby habitats cannot be excluded. We could not find any effect of the wind farm on either, morphs, sex distribution or condition of the common shore crab. Our study found no evidence that Lillgrund wind farm has a negative effect on populations of the common shore crab. This study provides the first quantitative and experimental data on the common shore crab in relation to offshore wind farms.

Phospholipids composition and metabolism in the hemolymph of Carcinus maenas (Crustacea, Decapoda)—Effect of temperature