Marine Hard Bottom Communities

Abstract

Biological invasions can have powerful effects on ecosystem structure and function and are seen as a threat to global biodiversity. Coastal systems are especially vulnerable, and we review the characteristics of invasions in marine benthic communities, beginning with the factors influencing initial introduction: vectors and propagule pressure. Invasive species have few characteristics in common, and their ease of establishment in an area does not correlate with the strength of their effects on the recipient community. We then examine what makes communities vulnerable, including disturbance and responses such as biotic resistance and facilitation. Community diversity and vulnerability do not appear to be related; instead, invasions appear idiosyncratic and the effects of diversity are identity-specific. Lastly, we describe the often dramatic effects of invasions, including those of introduced ecosystem engineers and subtle effects such as niche drift and genetic responses, but note that there is little evidence of invasives causing indigenous extinctions.