scholarly journals Prey preferences of invasive (Hemigrapsus sanguineus, H. takanoi) and native (Carcinus maenas) intertidal crabs in the European Wadden Sea

2021 ◽  
pp. 1-7
Author(s):  
Nadine Bleile ◽  
David W. Thieltges
Keyword(s):  
Carcinus Maenas ◽  
Field Studies ◽  
Predation Pressure ◽  
Hemigrapsus Sanguineus ◽  
Crab Species ◽  
Invasive Predators ◽  
Prey Preferences ◽  
Shore Crabs ◽  
Algal Prey ◽  
General Preference

Abstract Invasive predators can have wide-ranging effects on invaded ecosystems and identifying the prey spectra and preferences of invaders are important steps in assessing their potential impacts on native biota. In this study, we investigated prey preferences of two invasive crab species (Hemigrapsus sanguineus and Hemigrapsus takanoi) that recently invaded Europe's shores and compared them with preferences of native shore crabs (Carcinus maenas) of similar size. In laboratory experiments, all three crab species preferred animal over algal prey. In general, sessile mussels (Mytilus edulis) were preferred over motile amphipods (Gammarus locusta) by all three crab species but amphipod predation was lower in the invasive compared with the native crabs. For the two invasive crab species, this pattern was the same in treatments where prey was offered separately (no-choice treatments) or simultaneously (choice treatments), while for the native crabs, mussel preference disappeared in choice treatments. The general preference of mussels by all three crab species suggests that local invasions of crabs most likely lead to increased competition among crabs. In addition, given that local densities of invasive crabs are often much higher than those of native crabs, predation pressure on native mussels can be expected to strongly increase at invaded sites. In contrast, local predation pressure on amphipods may be less affected by the crab invasions. Further field studies are needed to establish the magnitude of competition and predation pressure exerted by the invaders under natural conditions.

scholarly journals Prey preferences, consumption rates and predation effects of Asian shore crabs (Hemigrapsus takanoi) in comparison to native shore crabs (Carcinus maenas) in northwestern Europe

2021 ◽  
Vol 51 (5) ◽  
Author(s):  
Annika Cornelius ◽  
Katerina Wagner ◽  
Christian Buschbaum
Keyword(s):  
Feeding Behavior ◽  
Wadden Sea ◽  
Feeding Habits ◽  
Carcinus Maenas ◽  
Shore Crab ◽  
Crab Species ◽  
Blue Mussels ◽  
Pacific Oysters ◽  
Shore Crabs ◽  
Consumption Rates

AbstractThe Asian brush-clawed shore crab Hemigrapsus takanoi was introduced to the northern Wadden Sea (southeastern North Sea) in 2009 and now represents one of the most abundant brachyuran crab species. Abundance studies revealed an increase of mean crab densities on mixed reefs of native blue mussels (Mytilus edulis) and Pacific oysters (Magallana gigas) from 18 individuals m−2 in 2011 to 216 individuals m−2 in 2020. Despite its current high densities only little is known about the feeding habits of H. takanoi, its effects on prey populations and on the associated community in the newly invaded habitat. We summarize results of individual field and laboratory experiments that were conducted to assess feeding habits and consumption effects caused by Asian brush-clawed shore crabs and, additionally, compare the feeding ecology of H. takanoi with the one of the native shore crab Carcinus maenas. Field experiments manipulating crab densities revealed that both crab species affected the recruitment success of blue mussels, Pacific oysters and Australian barnacles (Austrominius modestus) with highest number of recruits at crab exclusion. However, endobenthic polychaetes within the reefs were differently affected. Only the native C. maenas caused a significant reduction in polychaete densities, whereas the introduced H. takanoi had no effect. Additional comparative laboratory studies revealed that single C. maenas consume more juvenile blue mussels than Asian brush-clawed shore crabs of the same size class. When offering amphipods as a mobile prey species, we found the same pattern with higher consumption rates by C. maenas than by H. takanoi. For Asian but not for native shore crabs, we detected a sex-dependent feeding behavior with male H. takanoi preferring blue mussels, while females consumed more amphipods. Considering mean crab densities and feeding behavior, our results suggest that despite lower consumption rates of single crabs, Asian brush-clawed shore crabs can cause stronger impacts on prey organisms than the native C. maenas, because H. takanoi exceeds their densities manifold. A strong impact of the invader on prey populations is supported by low amphipod occurrence at sites where H. takanoi density is high in the study area. Thus, the introduced Asian brush-clawed shore crab is an additional consumer with significant effects on the associated community of mixed reefs of mussels and oysters in the Wadden Sea.

scholarly journals Prey size selection in invasive (Hemigrapsus sanguineus and H. takanoi) compared with native (Carcinus maenas) marine crabs

2019 ◽  
Vol 100 (1) ◽  
pp. 73-77
Author(s):  
Mark M. Bouwmeester ◽  
Andreas M. Waser ◽  
Jaap van der Meer ◽  
David W. Thieltges
Keyword(s):  
Resource Competition ◽  
Size Range ◽  
Prey Size ◽  
Carcinus Maenas ◽  
Hemigrapsus Sanguineus ◽  
Crab Species ◽  
Size Classes ◽  
Size Selection ◽  
Size Preference ◽  
Selection Of

AbstractIntroductions of predators can have strong effects on native ecosystems and knowledge of the prey size selection of invasive predators is pivotal to understand their impact on native prey and intraguild competitors. Here, we investigated the prey size selection of two invasive crabs (Hemigrapsus sanguineus and Hemigrapsus takanoi) recently invading European coasts and compared them with native shore crabs (Carcinus maenas) which are known to feed on similar prey species. In laboratory experiments, we offered different size classes of native blue mussels (Mytilus edulis) to different size classes of the crab species in an effort to identify the respective prey size preferences and potential overlap in prey size range of native and invasive crabs. In all three species, the preferred prey size increased with crab size reflecting general predator–prey size relationships. Prey size preference did not differ among the crab species, i.e. crabs showed similar mussel size preference in relation to carapace width. Given that additional morphological measurements showed that both of the invasive crab species have much larger claws relative to their body size compared with the native species, this finding was surprising and may relate to differential claw morphologies or structural strength. These results suggest that the invasive crabs exert predation pressure on the same size classes of native mussels as the native crabs, with potential effects on mussel population dynamics due to the high densities of the invaders. In addition, the overlap in prey size range is likely to result in resource competition between invasive and native crabs.

scholarly journals Influence of temperature on intraspecific, unbalanced dyadic contests between crabs

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7845
Author(s):  
Allan T. Souza ◽  
Felipe O. Ribas ◽  
João F. Moura ◽  
Claudia Moreira ◽  
Joana Campos ◽  
...  
Keyword(s):  
Carapace Width ◽  
Carcinus Maenas ◽  
Individual Characteristics ◽  
The Body ◽  
Shore Crab ◽  
Temperature Conditions ◽  
Red Color ◽  
Shore Crabs ◽  
Influence Of Temperature On ◽  
Globally Distributed

Intraspecific agonistic interactions are widespread across the animal kingdom, with many individual morphological and physiological characteristics playing important roles in the fate of disputes. Additionally, changes to environmental conditions can influence the outcomes of animal contests. The shore crab (Carcinus maenas) is a globally distributed species, present in numerous coastal and estuarine temperate systems around the world. Although shore crabs are highly tolerant to changes in temperature, this parameter has important physiological effects on the species’ ecology, while its effects on behavior are not fully understood. Our study aims to investigate how different individual characteristics (such as sex, color morphotype, carapace and chela morphology) and temperature conditions affect the dyadic interactions between shore crabs when disputing food resources. In general, the differences in carapace width between opponents, their sexes, color morphotypes and the temperature conditions interacted and were important predictors of the contest fate. We found that the body size and color morphotype of C. maenas determined the fate of dyadic disputes. However, the higher temperatures disrupted the well-established dominance of the larger red color morphotype individuals. Overall, the agonistic contest results suggest higher plasticity than previously acknowledged.

scholarly journals The ecology of shell shape difference in chirally dimorphic snails

2012 ◽  
Vol 81 (2) ◽  
pp. 95-101 ◽  
Author(s):  
Menno Schilthuizen ◽  
Martin Haase ◽  
Kees Koops ◽  
Sylvia M. Looijestijn ◽  
Sigrid Hendrikse
Keyword(s):  
Sexual Selection ◽  
Environmental Factors ◽  
Field Studies ◽  
Southeast Asian ◽  
Predation Pressure ◽  
Shell Shape ◽  
Ecological Traits ◽  
Shape Difference ◽  
Environmental Selection

The Southeast-Asian tree snail subgenus Amphidromus s. str. (Gastropoda Pulmonata: Camaenidae) is unusual among all gastropods for its genetic antisymmetry: populations consist of stable mixtures of individuals with clockwise (dextral) and counterclockwise (sinistral) coiling directions. Although previous studies in A. inversus suggest that this genetic dimorphism is maintained by sexual selection, it cannot be ruled out that environmental factors also play a role. Adult shell shapes in A. inversus are known to show subtle differences between both coiling morphs, and it is known that in snails in general, shell shape is under environmental selection, thus creating the possibility that micro-niche use of both coiling morphs differs. In this paper, we first confirm that hatchlings also differ in shell shape. We then proceed with field studies to compare dextral and sinistral juveniles and adults for (i) direction and rate of dispersal within the vegetation and (ii) micro-niche occupation. However, we failed to detect any difference in both ecological traits. In addition to earlier data that show that there is no clustering of morphs in the field and that both morphs suffer identical predation pressure, these new data do not provide any evidence for a role for environmental factors in maintaining the coil dimorphism in this species.

Capital or income breeding crabs: who are the better invaders?

Crustaceana ◽  
2014 ◽  
Vol 87 (14) ◽  
pp. 1648-1656 ◽  
Author(s):  
Yiwen Zeng ◽  
Colin McLay ◽  
Darren C. J. Yeo
Keyword(s):  
Life History ◽  
Gonadosomatic Index ◽  
Carcinus Maenas ◽  
Breeding Strategy ◽  
Life History Trait ◽  
Hepatosomatic Index ◽  
Hemigrapsus Sanguineus ◽  
Life History Pattern ◽  
Income Breeding ◽  
Capital Breeder

A recent study by Griffen et al. (2012) drew a link between invasiveness and breeding strategy (income or capital breeding), a hitherto unconsidered life-history trait, in crabs. The methods used by the authors identified Carcinus maenas (Linnaeus, 1758) as a capital breeder and Hemigrapsus sanguineus (De Haan, 1853) as an income breeder. We extend this association of breeding strategies and invasiveness to other crab species and note that crabs in general are capital breeders based on the concurrent opposing trends of gonadosomatic index and hepatosomatic index during secondary vitellogenesis (indicating an endogenous source of nutrients for reproduction). We identify possible reasons why H. sanguineus may be regarded as an exception to this brachyuran life history pattern. Given that some species could be capable of a mixed breeding strategy, we propose experimental methods for determining such strategies.

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