Shore Crab Hemigrapsus Sanguineus Research Articles

Predation of the non-native Asian shore crab Hemigrapsus sanguineus by a native fish species, the cunner (Tautogolabrus adspersus)

Predation of non-native species by native predators can impact the success of an invasion. Recently, the Asian shore crab, Hemigrapsus sanguineus, successfully invaded the northeastern coastline of the United States, reaching densities greater than 100crabs·m−2 in rocky intertidal areas. The goal of this study was to determine if a specialist fish predator of invertebrates, the cunner, Tautogolabrus adspersus, consumes the juvenile stage of H. sanguineus. In laboratory prey choice experiments, T. adspersus (10.2–22.1cm total length) consumed greater numbers of native mud crabs (family Panopeidae, 3.0–9.0mm carapace width) than H. sanguineus of similar sizes. T. adspersus also consumed more of the native blue mussel, Mytilus edulis, when paired with similar-sized H. sanguineus. Gut content analysis of 60 T. adspersus captured from intertidal zones with high populations of H. sanguineus in southeastern Massachusetts revealed low consumption of the invasive species; only 5 of 60 guts contained Asian shore crabs. Frequent prey items found in cunner guts included panopeid crabs, small snails, barnacles, and branching and encrusting bryozoans. Our results suggest that, as long as native prey species are present for consumption, T. adspersus will not exert high predation pressure on H. sanguineus.

Abundance of Invasive and Native Crab Larvae in the Mouth of Delaware Bay:Hemigrapsus sanguineusandUca Pugnax

We compare larval distributions of the invasive Asian shore crab Hemigrapsus sanguineus and the native fiddler crab Ucapugnax. Our study was conducted in the coastal ocean adjacent to Delaware Bay on the east coast of the United States. Subtidal circulation in the study area is dominated by the Delaware Coastal Current, which is formed by the estuarine plume that extends southward out of the bay and along the inner continental shelf. The offshore edge of the current is marked by a strong density front and by convergent circulation along the frontal boundary. Surface plankton tows were taken at fine-scale intervals along saw-tooth transects traversing the front on 3 consecutive days in early August. Coincident physical measurements delivered hydrographic data throughout the investigation. Results provided a synoptic view of larval distribution near the bay mouth and showed patchy occurrence of the 2 species within the sampling area. Approximately 8.7 × 105 U. pugnax larvae were collected during the study, compared with 2.5 × 104 H. sanguineus. Analysis of spatial distribution with respect to the coastal current showed a marked difference between early- and late-stage larvae for each species. Zoea stage I larvae were most common in the main stream of the coastal current. In contrast, the distribution of advanced stages was skewed toward the frontal region. Larvae entrained in the frontal circulation are likely retained near Delaware Bay, whereas those in the main stream of the coastal current may undergo long-distance transport along the continental shelf.

NO- and H2S brain systems of the Japanese shore crab Hemigrapsus sanguineus under conditions of anoxia

The topography and dynamics of the activity of the enzymes of the synthesis of nitric oxide (NO) and hydrogen sulfide (H2S) in the brain of the Japanese shore crab Hemigrapsus sanguineus after 1, 6, and 12 h ofanoxia was studied histochemically and immunocytochemically. Changes in the activity and number of NO- and CBS-immune-positive cells that take place due to anoxia and the intensity of which depends on the duration of the influence were revealed. The fact that the balance between the nitric oxide and hydrogen sulfide systems in the brain of the crabs H. sanguineus is preserved indicates the joint participation of those systems in the central regulation of adaptive mechanisms under the influence of anoxia and, apparently, plays an important role in the adaptation of these hydrobionts to oxygen deficit.

Genetic Variation in the Asian Shore Crab Hemigrapsus sanguineus in Korean Coastal Waters as Inferred from Mitochondrial DNA Sequences

Genetic variation in the Asian shore crab Hemigrapsus sanguineus was determined from partial mitochondrial DNA (mtDNA) sequences of the cytochrome b (Cytb) gene. Samples included 143 crabs from six localities along three coastlines in South Korea. A nucleotide sequence analysis revealed 38 variable sites in a 470-bp sequence, which defined 37 haplotypes. The haplotypes were not associated geographically and had a shallow genealogy. Pairwise <TEX>$F_{ST}$</TEX> tests and a two-dimensional scaling analysis revealed no significant genetic differentiation among most of the populations. The low pairwise comparison values, but significant genetic differentiation of a northeastern population from all other populations, might have been influenced by a restriction in gene flow caused by hydrographic conditions such as ocean boundaries. The high haplotype diversity, low nucleotide diversity, and time since H. sanguineus expansion in Korean coastal waters indicate rapid population growth and a recent, sudden expansion in the Late Pleistocene.

Development and behavior of megalopae of the non-native crab Hemigrapsus sanguineus in response to chemical cues from coastal fishes

Understanding the invasibility of marine species with complex life cycles requires examination of the ecology of both larval and adult stages. The goal of our study was to determine whether several species of coastal fish native to the western North Atlantic Ocean can consume megalopae of the nonindigenous Asian shore crab Hemigrapsus sanguineus and, if so, whether megalopae can respond to chemicals from potential fish predators by either molting faster to a benthic crab stage or exhibiting avoidance behaviors. Laboratory predation experiments showed that all fish species tested (cunner, Tautogolabrus adspersus; tautog, Tautoga onitis; grubby, Myoxocephalus aeneus; scup, Stenotomus chrysops; and mummichog, Fundulus heteroclitus) consumed H. sanguineus megalopae. When megalopae were reared in seawater in which fish or adult crabs had been housed, fish chemical cues had no effect on molting rate whereas chemicals from adult conspecific crabs accelerated molting. Behavioral responses of H. sanguineus megalopae to chemicals from fish and crabs were tested in still and flowing water. In still water, megalopae moved away from chemicals from T. adspersus and M. aeneus. In flowing water, chemicals from T. onitis caused a behavioral reaction that led to enhanced movement away from the source of the cue. All 3 species are related to fishes present in the native range of H. sanguineus. In contrast, chemicals from adult crabs and F. heteroclitus had no effect on behavior of megalopae. Behavioral responses of H. sanguineus megalopae to chemical cues from coastal fish species might function as antipredator strategies that enhance survival of this nonindigenous species.

Prey selection in crustacean-eating fishes following the invasion of the Asian shore crab Hemigrapsus sanguineus in a marine temperate community

The Asian shore crab Hemigrapsus sanguineus invaded the coast of Long Island Sound approximately twenty years ago and has become hyper-abundant and the most common crab species throughout the intertidal region. The success of the species is hypothesized to be due to reduced predation pressure in the invaded region. Recent observations document the expansion of H. sanguineus into shallow subtidal habitats (i.e., up to 5m depth and up to 180 crabs m−2 in some habitats) where it is more accessible to a diversity of crustacean-eating predators. The role that higher trophic level predators might play in controlling populations of invasive species has seldom been investigated in marine communities. Here we conducted a series of prey-preference experiments under laboratory conditions to determine whether crustacean-eating fishes prefer H. sanguineus rather than native crab species, and to provide insight into how predator size and habitat type influence prey preference. Small size-class predators exhibited a clear preference for H. sanguineus in paired offerings of the invader versus native crab species while paired offerings for large size-class fishes resulted in mixed findings. Small size class predators demonstrated no preference when prey were set in a range of sediment type treatments (i.e., sand, pebble, cobble), while paired offerings for large size class predators resulted in mixed findings. In general, the results from this study support our hypothesis that H. sanguineus is preyed upon preferentially by native crustacean-eating fishes but sediment type and predator size play an important role in determining that preference. Preference for the invasive crab over the native prey items in some settings suggests prey switching could occur in areas where the invader is abundant. We suggest that future field studies focus on the role that crustacean-eating fishes can play in biological control of invasive crab populations and how management of predators can influence the impact of invaders.

Reduced fecundity by one invader in the presence of another: A potential mechanism leading to species replacement

As invasive species proliferate and expand their ranges, they often interact either with natives or with other invasives across a broad geographic range. Moreover, because geographic ranges span a diversity of environments, the outcome of interactions between species pairs may vary spatially. The European green crab Carcinus maenas and the Asian shore crab Hemigrapsus sanguineus are both introduced species in North America where they co-occur over a large portion of the Atlantic coast. While interactions between the two crabs in the southern portion of this range within Long Island Sound resulted in the elimination of C. maenas within 2–3 years of H. sanguineus' arrival, species replacement appears to be taking much longer in northern areas within the Gulf of Maine. Previous work implicates predation by H. sanguineus on C. maenas recruits as the mechanism underlying species replacement. Here we explore an alternative or additional mechanism underlying this species replacement that can also account for the observed spatial variation in the timescale of species replacement between northern and southern areas. Specifically, we demonstrate that a previously documented shift in C. maenas diet which occurs in the presence of H. sanguineus can cause a reduction in C. maenas fecundity. This, combined with near-shore current patterns may explain the regional differences in the outcome of this species interaction.

Cystathionine β-synthase in the central nervous system of the shore crab Hemigrapsus sanguineus

Cystathionine β-synthase in the central nervous system of the shore crab Hemigrapsus sanguineus

Mating and Sperm Storage of the Asian Shore CrabHemigrapsus sanguineus

The Asian shore crab Hemigrapsus sanguineus is the principal invasive crab in many intcrtidal habitats on the east coast of the United States between Cape Hatteras and Maine. Previous work has described general aspects of mating for the genus Hemigrapsus; however, there has been no explicit study of mating behavior in H. sanguineus, and there has been little consideration of how this behavior might influence the success of H. sanguineus as a bio-invader. The objective of our investigation was to document the mating behavior of H. sanguineus under laboratory conditions and compare this pattern of behavior with that of other species of Hemigrapsus. Our observations show that mating in H. sanguineus was always initiated by the male and that both the male and female had calcified exoskeletons at the time of copulation. Small males were sometimes successful in securing mates, even in the presence of larger males. However, the male was larger than the female in 67% of the observed copulations. Duration of copulation in H. sanguineus was relatively long compared with other species of Hemigrapsus, and averaged ∼30 min. H. sanguineus differs from other species of Hemigrapsus in terms of positioning during mating. H. sanguineus typically used a vertical position relative to the substratum, with both crabs standing and facing each other, ventral surface to ventral surface. This position facilitated some degree of mobility in the copulating pair. Females were receptive to copulation within a few days of larval release, and were also capable of storing sperm and producing at least 2 broods from a single copulation. Mean incubation time of newly extruded eggs was around 16 days, and females often produced a second brood within a few days of larval release. Thus, an individual H. sanguineus could produce 2 broods within 40 days and presumably additional broods with subsequent copulation. This pattern of reproduction provides enhanced fecundity relative to co-occurring native species of crabs.

Stress-induced changes in the nitric oxide system of shore crabs living under different ecological conditions

The NO synthesis system in the brain and hemolymph of shore crabs Hemigrapsus sanguineus (Decapoda: Varunidae) living under different ecological conditions was examined under normal conditions and under acute stress. Intact crabs sampled from an area with a high anthropogenic load had a higher initial level of NO compared to crabs from a relatively clean location. After acute damaging exposure, the dynamics of the NO system activity in crabs from different stations differed markedly. The number of NO-positive elements in the brain and the level of NO metabolites in the hemolymph dramatically increased immediately after injuries in all groups of crabs. One hour after acute exposure, the expression of inducible NO-synthase in the protocerebral neurons was observed in crabs inhabiting the chronically polluted area. These results demonstrate for the first time the influence of pollution on the activity of NO-ergic processes and the involvement of nitric oxide in the formation of behavioral defense response in crustaceans under acute stress.

Molting of megalopae of the Asian shore crab Hemigrapsus sanguineus in intertidal habitats of Northeastern North America

Planktonic larvae of many benthic taxa settle and metamorphose in response to certain habitat cues. Although laboratory investigations of the importance of potential cues are numerous, field experiments are less common. We modified a field caging technique first developed for analysis of molting specificity of fiddler crab megalopae to test potential habitat cues affecting molting of megalopae of the non-native Asian shore crab Hemigrapsus sanguineus (de Haan). Potential cues consisted of waterborne substances from 2 potential habitats (cobble beach and salt marsh), and the material used to construct experimental cages. Experiments were conducted in 2002, 2003, and 2004 in Massachusetts and New York (USA). Megalopae (4 or 5 d post molt) were placed in either nylon mesh (500 μm) cages open to flooding seawater or transparent glass jars containing filtered seawater. Cages and jars were placed at identical intertidal heights at the field sites and retrieved 3 or 4 d later. The proportion of megalopae molting to the first crab stage was determined after the period of field exposure and for 2 d thereafter. More megalopae molted in cages than jars placed in the adult habitat (cobble beach) and in a marsh without adults. The cage mesh had little effect on molting response. We conclude that waterborne cues stimulate molting of H. sanguineus megalopae, and that cues are present in both the adult habitat and marsh. Molting of H. sanguineus megalopae is substantially less habitat-specific than molting of native fiddler crab megalopae.

Response of the Asian shore crab Hemigrapsus sanguineus to metamorphic cues under natural field conditions

For brachyuran crabs like Hemigrapsus sanguineus, survival past the planktonic life stage requires settlement out of the water column onto appropriate benthic habitat, followed by metamorphosis to the 1st juvenile stage. In the laboratory, H. sanguineus has been shown to respond to cues produced by conspecific adults and to various cues associated with the substratum. The objective of the present investigation was to determine the response of megalopae to cues produced by natural populations of adult H. sanguineus. In this study, laboratory-reared megalopae were deployed in cages at four locations along each of two transects that extended 20 m from rocky intertidal habitat that contained a dense population of adult H. sanguineus. One transect extended perpendicular to shore and into open water, while the second extended parallel to shore and adjacent to salt-marsh habitat. The percentage of megalopae undergoing metamorphosis was greatest in the cages that were closest to the adult population and diminished with distance from that population, regardless of transect. Moreover, a comparison of cages at comparable positions on the respective transects showed lower percentage metamorphosis in cages on the marsh transect than on the open-water transect. Our findings are coherent with results of previous laboratory studies and indicate that H. sanguineus megalopae can sense water-soluble metamorphic cues produced by conspecific adults at distances up to a few meters from the source.

Predation on juveniles of Crepidula fornicata by two crustaceans and two gastropods

Crepidula fornicata, the slippershell snail, while native to New England, has now become a successful invasive species along coastlines in many other parts of the world. This study considers the possible control of native populations by several common predators: the invasive shore crab Hemigrapsus sanguineus, one species of pagurid hermit crab ( Pagurus longicarpus), and juveniles of the drilling gastropods Nucella lapillus and Urosalpinx cinerea. In the laboratory, juveniles of C. fornicata were especially vulnerable to the two crustacean predators tested, and to a lesser extent vulnerable as well to predation by the oyster drill U. cinerea; in choice tests, young oyster drills ate barnacles and mussels rather than slippershell snails, but ate C. fornicata when offered no other choice. Juveniles of two other Crepidula species ( C. plana and C. convexa) were less susceptible to predation by hermit crabs, probably due to differences in juvenile shell morphology and growth trajectories. Remarkably, juvenile dogwhelks ( N. lapillus) ate no Crepidula prey over several months in the laboratory, even in the absence of alternative food and although they readily consumed blue mussels. Additional work is needed to determine the role of crustacean and other predators in regulating the growth of native populations of C. fornicata in the field and to determine the extent to which the explosive growth of at least some invasive Crepidula populations reflects escape of juveniles from native predators.

First record of the Japanese shore crab Hemigrapsus sanguineus (de Haan, 1835) (Brachyura: Grapsoidea: Varunidae) from the Black Sea

1* , Victor Niţa Abstract The Japanese shore crab Hemigrapsus sanguineus is recorded for the first time from a Black Sea locality: Tomis Marina in Constanţa, Romania. The suggested vector of introduction is as adults in the hull fouling of yachts. The species has not established and salinity requirements for larval development make it unlikely that it will ever establish in the Black Sea.

Asian Shore Crabs Hemigrapsus spp. (Crustacea: Brachyura: Grapsoidea) continue their invasion around the Cotentin Peninsula, Normandy, France: Status of the Hemigrapsus population in 2009

This paper reports on the state of the Asian shore crab Hemigrapsus sanguineus (de Haan, 1835) population around the Cotentin Peninsula (Normandy, France) for 2009. As in 2008, the year of the first survey, the northern and eastern Cotentin coasts remain the most densely colonised. On the western shore, H. sanguineus remains rare, except in two sites not surveyed in 2008. In the east most colonised sites, Gatteville-Phare and La Hougue, the populations for both years indicate a rapid increase of abundance: maximum density > 50 .ind.m -2 in 2009 compared to 10 ind.m -2 in 2008. This observation probably demonstrates that the species' current significant increase is comparable to that of an invasive species. A second species of Asian shore crab Hemigrapsus takanoi Asakura & Watanabe, 2005 was only present on one eastern site off Saint-Vaast-La-Houge, but remains isolated.

Induction of metamorphosis in the Asian shore crab Hemigrapsus sanguineus: Characterization of the cue associated with biofilm from adult habitat

Recruitment of crabs to nursery habitat requires settlement of the megalopal stage on suitable substratum followed by metamorphosis into the first juvenile stage. Reducing the time to metamorphosis may result in higher recruitment and survival. Previous work has shown that metamorphosis of the Asian shore crab is accelerated by cues from three different sources: (a) water-soluble exudate produced by conspecific adult crabs; (b) biofilm covering rocks in natural habitat for this species; and (c) abiotic rock from natural habitat. The objective of the present investigation was to characterize the metamorphic cue associated with biofilm from rocky intertidal habitat and to compare the three metamorphic cues (exudate from conspecific adults, biofilm from rocky intertidal, and texture of substratum) that have been identified for H. sanguineus. Results of our study show that megalopae of the Asian shore crab respond strongly to biofilm associated with rocky intertidal habitat that has developed for at least 8 days. We also found that megalopae respond to textured rock surfaces from natural habitat, even when those surfaces had been rendered abiotic. The cue remains active after the biofilm has been exposed to − 20 ºC for 12 h, but is de-activated by a few minutes exposure to 100 °C. Moreover, the biofilm cue appears to work in synergy with cues from other sources, but requires actual contact with the biofilm. Our findings show that addition of biofilm to an abiotic textured rock surface significantly decreases mean time to metamorphosis, and simultaneous exposure of megalopae to biofilm-covered rock and to exudate from adult H. sanguineus decreases mean time to metamorphosis even further. The response of this species to multiple cues—and particularly to biofilm in the absence of adult conspecifics—provides a clear advantage in the colonization of virgin habitat and helps explain the very rapid spread of this invasive species along the majority of the east coast of the United States in only two decades.

Differential escape from parasites by two competing introduced crabs

Although introduced species often interact with one another in their novel communities, the role of parasites in these interactions remains less clear. We examined parasite richness and prevalence in 2 shorecrab species with different invasion histories and residency times in an introduced region where their distributions overlap broadly. On the northeastern coast of the USA, the Asian shorecrab Hemigrapsus sanguineus was discovered 20 yr ago, while the European green crab Carcinus maenas has been established for over 200 yr. We used literature and field surveys to evaluate parasitism in both crabs in their native and introduced ranges. We found only 1 parasite species infecting H. sanguineus on the US East Coast compared to 6 species in its native range, while C. maenas was host to 3 parasite species on the East Coast compared to 10 in its native range. The prevalence of parasite infection was also lower for both crabs in the introduced range compared to their native ranges; however, the difference was almost twice as much for H. sanguineus as for C. maenas. There are several explanations that could contribute to C. maenas’ greater parasite diversity than that of H. sanguineus on the US East Coast, including differences in susceptibility, time since introduction, manner of introduction (vector), distance from native range, taxonomic isolation, and the potential for parasite identification bias. Our study underscores not just that non-native species lose parasites upon introduction, but that they may do so differentially, with ramifications for their direct interactions and with potential community-level influences.

Establishment of the invasive Asian shore crab Hemigrapsus sanguineus (De Haan, 1835) (Crustacea: Brachyura: Grapsoidea) from the Cotentin Peninsular, Normandy, France

The occurrence of the invasive Asian shore crab Hemigrapsus sanguineus (de Haan, 1835), around the Cotentin Peninsular, Normandy, France, is reported. The northern and eastern Cotentin coasts are more densely colonised (maximum density ≅ 10 ind.m -2 ) than western shore, where the crab remains rare. These colonisation and establishment demonstrate probably the western progression of the species from its initial introduction into the Le Havre harbour during 1999.

Induction of Metamorphosis in the Asian Shore Crab Hemigrapsus sanguineus: Effects of Biofilms and Substratum Texture

Since its initial invasion in the late 1980s, the Asian shore crab Hemigrapsus sanguineus has spread over 650 km along the Atlantic Coast of the United States. Larvae of this species can live in the water column for over 3 weeks, which provides ample time for transport to new locations. Previous research on the settlement and metamorphosis of H. sanguineus showed that postlarvae (megalopae) accelerate metamorphosis in response to very specific water-soluble cues. However, the response to substratum cues appears to be much broader. The experiments presented here were designed to test the metamorphic response to biofilms and substratum texture. We found that nylon mesh with pore size of 100 and 1,000 μm had a greater effect on mean time to metamorphosis than 10 and 2,000 μm mesh. Results also showed a positive response to natural rock substrata, and this response was most pronounced when megalopae were exposed to substrata with rough texture. In addition, we found that a combination of a textured surface and a natural biofilm accelerated metamorphosis more than either an abiotic substratum or a smooth surface covered with natural biofilm. A final experiment compared the effect of textural cues to that of a water-soluble cue found in exudate from adult H. sanguineus. Results indicated that both types of cue-induced metamorphosis to the same extent.

Stimulation of molting in megalopae of the Asian shore crab Hemigrapsus sanguineus: physical and chemical cues

The Asian shore crab Hemigrapsus sanguineus is a recent invader and abundant mem- ber of rocky intertidal coastlines of the eastern USA. Understanding factors influencing the settlement and metamorphosis of its larvae is important for predict- ing colonization of the species. For many species of brachyuran crustaceans studied to date, chemical cues in the natural environment stimulate molting of megalopae, the final larval stage, to the first crab stage, whereas physical cues alone have little or no effect. However, physical structure can influence the abundance of juvenile and adult crabs. In this study, I tested whether physical/structural and chemical cues stimulate molting of H. sanguineus in the labo- ratory. Molting rates of megalopae exposed to exu- dates from adult crabs (H. sanguineus and the green crab Carcinus maenas) and different physical cues varying in structural complexity (rocks with or with- out biofilms, silt particles, nylon mesh used in aqua- culture) were monitored. Megalopae molted sooner to the first crab stage in the presence of exudates of both crab species, rocks with and without biofilms, and all nylon meshes tested regardless of the size of mesh openings. By separating the effects of chem- ical and physical cues, this study shows both to be important during settlement and metamorphosis of Asian shore crab megalopae, potentially contributing to its successful colonization of North Atlantic coast- lines.