John has been comparing how native and non-native crabs feed on early stages of soft-shell clams, a common species from the sediments along the PEI coast. Invasive species, such as the invasive green crab, can have a number of detrimental effects on our native species, both by feeding directly on them, and by outcompeting them for available food resources. For his summer research, John carried out a number of laboratory experiments looking at the feeding rates in the non-native green crab (C. maenas) and the native black-clawed mud crab (Panopeus herbstii), and compared the results for the different predator species and for a variety of different kinds of substrates. He set up his aquatic tanks so that they either had sand, oyster shell, or mussel shell covering the bottom of the tank, then he compared the rate that the crabs fed on the clams in the different substrates. So far, he has found that the invasive green crabs are more efficient predators than the mud crabs and that the type of substrate had a strong effect on the native mud crab, but no effect on the green crab. These results suggest that the invasive species might have a negative effect on the native species by outcompeting it for food.
John Greenan - Biology
John has been comparing how native and non-native crabs feed on early stages of soft-shell clams, a common species from the sediments along the PEI coast. Invasive species, such as the invasive green crab, can have a number of detrimental effects on our native species, both by feeding directly on them, and by outcompeting them for available food resources. For his summer research, John carried out a number of laboratory experiments looking at the feeding rates in the non-native green crab (C. maenas) and the native black-clawed mud crab (Panopeus herbstii), and compared the results for the different predator species and for a variety of different kinds of substrates. He set up his aquatic tanks so that they either had sand, oyster shell, or mussel shell covering the bottom of the tank, then he compared the rate that the crabs fed on the clams in the different substrates. So far, he has found that the invasive green crabs are more efficient predators than the mud crabs and that the type of substrate had a strong effect on the native mud crab, but no effect on the green crab. These results suggest that the invasive species might have a negative effect on the native species by outcompeting it for food.
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