Community disruption in small biogenic habitats: A coastal invader overcomes habitat complexity to alter community structure

• Published in: PloS one Vol. 15; no. 10; p. e0241116
• Main Authors: Malyshev, Andrey V, Tummon Flynn, Paula, Cox, Ruth, Duarte, Cristian, Quijón, Pedro A
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 26-10-2020; Public Library of Science (PLoS)
• Subjects: Animals; Biology and Life Sciences; Biotic communities; Brachyura; Canada; Carcinus maenas; Clumps; Coastal ecology; Community structure; Complexity; Crustaceans; Density; Dyspanopeus sayi; Earth Sciences; Ecology and Environmental Sciences; Environmental aspects; Experiments; Feeding rates; Field tests; Food Chain; Habitats; Indigenous species; Introduced Species; Invertebrates; Mollusks; Mud; Mussels; Mya; Mya arenaria; Mytilus edulis; Predation; Predators; Predatory Behavior; Prey; Sediments; Shorelines; Soil density; Canada; Chile; Prince Edward Island Canada
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0241116

Non-indigenous species are often identified as threats to native species and communities. Yet, the mechanisms that enable many of these invaders to thrive and alter their newly invaded habitats are still not fully understood. This applies to habitats such as widespread sedimentary shorelines characterized by the presence of scattered biogenic clumps of blue mussels (Mytilus edulis) structurally more complex than bare sediments. In Atlantic Canada, some of these shorelines are numerically dominated by native mud crabs (Dyspanopeus sayi) but have been gradually invaded by the European green crab (Carcinus maenas). This study describes between-habitat (mussel clump vs. bare sediment) differences in density and diversity of invertebrates. It also tests the impact of juvenile green crabs in comparison to native mud crabs using two approaches: First, measuring habitat-related differences in these crabs' feeding rates on a common prey (soft-shell clams, Mya arenaria). Second, measuring their influence on invertebrate communities associated with mussel clumps. The results show that mussel clumps hold higher invertebrate density and diversity than surrounding sedimentary bottoms. In the laboratory, the feeding rates of native mud crabs were dependent on the type of habitat (sand flat > mussel clump), whereas those of green crabs were significantly higher and unrelated to the habitat in which predation occurred. In field experiments, juvenile green crabs were also the only predators that changed community structure in the mussel clump habitat. These results indicate that green crabs can cause a significant impact on native species and communities. Moreover, they suggest that the ability of this species to overcome the refuge provided by complex biogenic habitats for prey may represent an unexplored mechanism to explain this invader's expansion here and elsewhere.