Links between estuarine condition and spatial distributions of marine invaders

Abstract

Aim Non‐indigenous species pose a significant threat to the environment and to global economies. Predictive and preventative measures are widely considered more effective in curtailing invasions than are eradication or control measures. Of key importance in the prediction of regional invasion risk are the environmental conditions that enable successful establishment. Location We surveyed native and non‐indigenous sessile invertebrate diversity in each of two commercial (600–1500 vessels per year) and two recreational estuaries (seven to nine marinas) in New South Wales, Australia. Methods A nested hierarchical design was employed to investigate variation in sessile invertebrate diversity at the scales of site (1–3 km apart) and estuary (40–180 km apart). Settlement plates (15 × 15 cm) were used to sample invertebrates and background heavy metal loads were assessed using bioaccumulation in experimentally deployed oysters. Other physico‐chemical variables were monitored monthly. Manipulative experiments were used to test the direct effects of exposure to copper and tributyltin (TBT) antifouling paints on sessile invertebrates. Results Native and non‐indigenous species richness differed at various spatial scales, but showed no consistent difference between commercial and recreational estuaries. Instead, individual species distributions were strongly related to metal contamination, temperature, turbidity and pH. In experimental studies, several species (mostly invaders) were more abundant on plates exposed to copper and/or TBT antifouling paints. We found higher levels of copper (and in some instances TBT) in recreational marinas than in commercial harbours. Main conclusions Our results demonstrate the importance of metal pollution and physico‐chemical variables in the establishment of invaders in new regions. We have identified several native Australian species that have been exported overseas and suggested mechanisms contributing to their transport and establishment. Combining physico‐chemical information about donor and recipient regions with species tolerances could go some way to predicting where future invasions may occur.

Aquatic pollution increases the relative success of invasive species

“…For example, exotic species now in San Francisco Bay have survived conditions during long-distance transport, such as those encountered in metal ballast tanks or on the hulls of ships making transoceanic voyages hulls. In general, within anthropogenically-modified systems, these and many other exotics may have an advantage over natives (Dafforn et al 2009), as natives are now existing in conditions different than those in which they have evolved. This has been called the ''selection regime alteration'' hypothesis, where exotics are in essence ''preadapted'' to conditions in recipient environments (Byers 2002).…”

Top-Down Impacts of Sea Nettles (Chrysaora quinquecirrha) on Pelagic Community Structure in Barnegat Bay, New Jersey, U.S.A.

“…Additionally, the hardening of shorelines and elimination of natural vegetated regions create the potential that tolerant fouling organisms can colonize and expand in these degraded systems (Simkanin et al, 2012). Many coastal estuaries are plagued by poor water quality and increasing inclusion of nonnative species (Dafforn, Glasby, and Johnston, 2009). As such, developed coastal estuaries are being defined by lowered species richness and diversity as invaders monopolize available space (Cohen and Carlton, 1998;Ruiz et al, 1997), the quantity and toxicity of pollutants (Long et al, 1996), the loss of natural habitats (Lathrop and Bognar, 2001), and simplification of food webs through redirection of energy, species introduction, and overfishing (Byrnes, Reynolds, and Stachowicz, 2007).…”

N-acetyl-β-d-glucosaminidase activity in feral Carcinus maenas exposed to cadmium

“…Investigation of the enhanced tolerance should thus be accounted for in monitoring programmes employing NAGase as biomarker, to avoid data misinterpretation. Tolerance to metal pollution has been considered as a trait that may facilitate adaptation to contaminated estuaries (Dafforn et al, 2009), an important aspect given that C. maenas is also a well known widespread non-indigenous species that has colonised metal polluted areas (Cohen et al, 1995;Klassen and Locke, 2007).…”