Predation by crustaceans on native and non-native Baltic clams

Abstract

We studied the effect of crustacean predators on native/non-native Macoma balthica bivalves in aquarium experiments. North Sea M. balthica (NS Macoma) were recently observed in the southern Baltic Sea. They differ genetically and in terms of morphology, behaviour and evolutionary history from Baltic Sea M. balthica (BS Macoma), and this may affect predation pressure and community structure. We hypothesised that predators consume more of the prey they co-exist with. NS Macoma and BS Macoma were exposed to crustacean predators common in the North Sea (Carcinus maenas and Crangon crangon) and in the Baltic Sea (C. crangon and Saduria entomon). Contrary to our hypotheses, the North Sea predators ate more BS Macoma, and S. entomon ate more NS Macoma. The crush-limited C. maenas preyed more on globular BS Macoma, whereas S. entomon, which do not crush but pry open the bivalve shell, ate more NS Macoma, which have a lighter (thus probably thinner) shell than BS Macoma. When NS and BS Macoma were offered together, BS Crangon ate more NS Macoma. We also studied BS Crangon consumption of M. balthica to assess whether sizes offered fall within the size spectrum that C. crangon can eat. Small (20 to 40 mm long), medium (40 to 50 mm) and large (50 to 60 mm) C. crangon especially ate small M. balthica. Differences in shape, size and meat/shell weight ratio between the BS and NS Macoma partly explained the differences in the susceptibility to predation by native and non-native predators.

Interactions between the invasive European green crab, Carcinus maenas (L.), and juveniles of the soft-shell clam, Mya arenaria L., in eastern Maine, USA

“…Since the six DU clams were all within a unit containing a crab, all clams were scattered on the surface and not discolored (as opposed to being burrowed in the sediment with both valves discolored black, as was the fate of the three DU clams from the control units), and no tissue was present in the valves, it would appear that the crab somehow consumed the clams without leaving any discernible shell damage. Because green crabs are known to crush juvenile, infaunal bivalves (Ejdung et al, 2009;Ropes, 1968;this study), this result is surprising. Perhaps some individuals of C. maenas are able to consume juveniles of Mya as individuals of the brachyuran crab, Hemigrapsus sanguineus (25-40 mm CW), is known to consume larger M. arenaria (ca.…”

Environmental context determines the impact of titanium oxide and silver nanoparticles on the functioning of intertidal microalgal biofilms

“…Biovolume of individuals were calculated using geometric shapes and published morphometric relationships for Hydrobia, Macoma (mollusca) and Hediste polychaete annelid worms. [69][70][71]…”

Characteristics of native predators are more important than those of alien prey in determining the success of biotic resistance in marine systems

“…For example, Twardochleb et al (2012) suggest that biotic resistance will be effective when the feeding rates of native predators outstrip that of alien prey reproduction but fail to address prey preference or the influence of alternative prey. In contrast, numerous publications predict that preference for an alien prey over a native prey is key for effective resistance (Carlsson et al 2009;Ejdung et al 2009;Epelbaum et al 2009;Shinen et al 2009). Studies more focussed on alien prey predict that species with high propagule pressure (Hollebone and Hay 2007), r-selected life histories (Morton 1997) or pre-adaptations to the recipient region's climatic conditions (Bomford et al 2010) have high probabilities of invasion success, irrespective of native predator abundance or behaviour.…”