Physical habitat attribute mediates biotic resistance to non-indigenous species invasion

Abstract

A soft-shelled non-indigenous clam, Nuttallia obscurata, has invaded coastal soft-sediment habitats of the northeastern Pacific. In a survey of 35 sites within the San Juan Islands, Washington, USA, Nuttallia was found almost exclusively in sandy substrates, higher in the intertidal than most native clams (>1 m above mean lower low water). The distinctive distribution of Nuttallia suggested that tidal height and sediment composition may be important physical factors that control its refuge availability, regulating its exposure to predation and ultimately the success of its invasion. I tethered Nuttallia for 24 h in the high intertidal where it is typically found and in the low intertidal at an elevation where it was never found. Clams restrained to the surface suffered high mortality from crab predation at both tidal heights, whereas control clams with unrestricted burrowing movement exhibited high mortality rates only in the low intertidal. In a second experiment, I transplanted sediment within and between the two intertidal heights to measure effects of tidal height and sediment type on survival and burial depth of Nuttallia. At both tidal heights all clams placed on mud-cobble substrate, naturally common in the low intertidal, suffered high mortality rates (>60% in 24 h). Nuttallia on loosely packed sand substrate, naturally found in the upper intertidal, survived much better, however, because they buried deeper than in the tightly packed mud. Caged control clams at both tidal heights suffered no mortality. Apparently native predators are mitigating community level impacts of an invader by excluding Nuttallia completely from some beaches with improper sediment characteristics or relegating it in others to a zone not often inhabited by native species, thereby reducing potential competitive interactions. These findings show that a physical habitat characteristic can mediate biotic resistance to an invader and thus control invasion success and community-level impacts. Generally, such physical-biological interactions may explain some of the reported site-to-site variability in invasion success, as well as the patchy distribution of many soft-sediment infaunal species.

Abiotic impacts on spatial and temporal distribution of Corbicula fluminea (Müller, 1774) in the River Minho estuary, Portugal

“…Thus C. fluminea can achieve higher biomasses and growth rates in habitats with high organic matter content (Vaughn and Hakenkamp, 2001). Sediment characteristics are an important factor in the distribution of benthic species, including non-indigenous invasive bivalve species (Mellina and Rasmussen, 1994;Byers, 2002;Jones and Ricciardi, 2005). The model, showed higher biomasses were correlated with higher values of very coarse sand, fine sand and organic matter (with this last abiotic factor correlating with very fine sands and silt and clay).…”

Manipulating the intrinsic parameters of propagule pressure: implications for bio‐invasion

“…In many systems, including hard substrate invertebrate communities, predation is a dominant form of perturbation or disturbance. Recent evidence, however also suggests a strong resistive effect of endemic predators on invasion (Byers 2002, Ruesink 2007, Soledad Lopez et al 2010, making predictions of predatory effects less intuitive. Predation may have direct negative impacts on new invaders, particularly if the same, or similar, predator species are present in both the native and introduced ranges of invasive prey (Soledad Lopez et al 2010).…”

Abiotic and biotic resistance to grass invasion in serpentine annual plant communities

“…However, the eVect of the interactions among abiotic and biotic sources of community resistance on the success of invaders is only beginning to be understood. Moreover, the few studies on these interactions that exist come primarily from animal systems (e.g., Byers 2002;Holway et al 2002).…”

“…The abiotic environment can also aVect invasions by inXuencing the outcome of biotic interactions (Byers 2002;Holway et al 2002), generating an interaction between these two sources of resistance. Such interactions can amplify or dampen overall community resistance.…”