Good or bad moves in the southern Benguela?

Laura K. Blamey (1), John J. Bolton (2), George M. Branch (3), Éva E. Plagányi (4), Tamara B. Robinson (5)

1 Marine Research Institute, Department of Biological Sciences, University of Cape Town, Rondebosch, Western Cape, 7701, laura.blamey@uct.ac.za,

2 Marine Research Institute, Department of Biological Sciences, University of Cape Town, Rondebosch, Western Cape, 7701, john.bolton@uct.ac.za

3 Marine Research Institute, Department of Biological Sciences, University of Cape Town, Rondebosch, Western Cape, 7701, mbranch@mweb.co.za

4 CSIRO Oceans and Atmosphere Flagship, Queensland BioSciences Precinct (QBP), St Lucia, Brisbane, Queensland, 4072, Eva.Plaganyi-lloyd@csiro.au

5 Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland, Western Cape, 7602,  trobins@sun.ac.za

Laura K. Blamey1, John J. Bolton2, George M. Branch3, Éva E. Plagányi4, Tamara B. Robinson5,

Shifts in species ranges, changes in species abundance and the introduction of non-native species are some of the reflections of species “on the move” and are almost always directly or indirectly related to human impacts. But are all moves bad, and what might dictate a bad mover vs. a good mover? We provide some examples of “species on the move” from nearshore coastal regions in the southern Benguela and compare these with similar systems elsewhere in the world.  In these examples we consider why and how the species moved and what effect this had on the rest of the ecosystem. First, the spiny lobster Jasus lalandii has shifted eastwards, with significant repercussions for species such as the urchin Parechinus angulosus and abalone Haliotis midae, but also for the ecosystem as a whole. In most kelp bed systems, an increase in spiny lobster and a decline in urchins would be viewed as a “good move”, but is this true for the South African system and if not, why not? Second, the kelp Ecklonia maxima has also moved, with changes in both abundance and distribution having occurred, but these changes are opposite to those in many other temperate systems and go against the predicted global trend. Finally, there have been major changes on rocky intertidal shores with the introduction and spread of non-native species and the retraction of native species, with positive and negative effects on different components of the community.