Patterns and traits associated with invasions by predatory marine crabs

Cheruscha Swart,Tamara B Robinson,Vernon Visser

doi:10.3897/neobiota.39.22002

Cheruscha Swart, Tamara B Robinson + Show 1 more

Open Access

https://doi.org/10.3897/neobiota.39.22002

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Journal: NeoBiota	Publication Date: Aug 28, 2018
Citations: 9	License type: CC BY 4.0

Affiliation: Stellenbosch University, University of Cape Town

Abstract

Predatory crabs are considered amongst the most successful marine invasive groups. Nonetheless, most studies of these taxa have been descriptive in nature, biased towards specific species or regions and have seldom considered traits associated with invasiveness. To address this gap in knowledge, this study presents a global review of invasions by this group and applies biological trait analysis to investigate traits associated with invasion success. A total of 56 species belonging to 15 families were identified as having spread outside their native ranges. The family Portunidae supported the highest number of alien species (22). Most crabs had their origin in the North West Pacific IUCN bioregion while the Mediterranean Sea received the most species. No traits associated with successful establishment were identified, but this finding may reflect the paucity of basic biological knowledge held for many species. This lack of foundational knowledge was unexpected as crabs are large and conspicuous and likely to be well studied when compared to many other groups. Addressing this knowledge gap will be the first step towards enabling approaches like biological trait analysis that offer a means to investigate generalities in invasions.

Highlights

Studies reviewing the distribution and vectors of marine alien species are numerous and include those that focus at the global (e.g. Bax et al 2003, Ruiz et al 2011) and regional scale (e.g. Europe (Galil et al 2014); South Africa (Mead et al 2011))
The largest number of established species was from the family Portunidae and included species such as the European shore crab, Carcinus maenas
Other families supporting notable numbers of established alien species were the Varunidae, Cancridae, Pilumnidae and Grapsidae, highlighting a positive correlation between the number of alien species known from a family and the number of established species in that family (Spearman’s rank correlation; r = 0.79, p

Summary

Introduction

Studies reviewing the distribution and vectors of marine alien species are numerous and include those that focus at the global (e.g. Bax et al 2003, Ruiz et al 2011) and regional scale (e.g. Europe (Galil et al 2014); South Africa (Mead et al 2011)). Bax et al 2003, Ruiz et al 2011) and regional scale (e.g. Europe (Galil et al 2014); South Africa (Mead et al 2011)) These studies are often descriptive in nature, providing first insights into the marine invasions of a region. There has been a move to advance this approach by identifying invasion patterns and applying biological trait analysis to identify taxa that are likely to invade. The use of these approaches adds statistical power to the conclusions drawn about the factors that may play a role in the spread and establishment of alien species (Cardeccia et al 2018). Such reviews can be insightful as they focus on highly invasive taxa from well-studied groups, enabling detailed analyses of factors driving their invasion success (Kolar and Lodge 2002, Hänfling et al 2011)

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