Marine Protected Areas in connected land-seascapes

Its not just what we take-out !

In spatially connected systems, MPAs may not be a silver-bullet for managers.

The idea that changes to fishing can result system wide changes often assumes strong top-down effects. The existence of such trophic cascades requires 'key-stone' species at each trophic level. Strong control of tropical and temperate habitats via benthic grazing, as a function of direct or indirect fishing pressure, has had a persuasive influence on coastal managers throughout Australia. 

We have tremendous difficulty with the application of these ideas to South Australia's coast.  Instead, South Australians may need to be more concerned about what they add to their coast (coastal run-off) than what they remove from their coast (abalone, urchins, fish).  Our research has identified land-to-sea connections that links intensity of land-use to extent to subtidal habitat-degredation (kelp loss).

Comparison of south-coast recovery (after >2 years):

 References:

• Connell SD, BD Russell et al. 2008. Recovering a lost baseline: missing kelp forests from a metropolitan coast.  Marine Ecology Progress Series. 360:63-72
• Russell, BD & Connell SD 2007. Response of grazers to sudden nutrient pulses in oligotrophic v. eutrophic conditions. Marine Ecology Progress Series 349:73-80
• Gorgula, SK & Connell, SD 2004. Expansive covers of turf-forming algae on human-dominated coast: the relative effects of increasing nutrient and sediment loads. Marine Biology 145: 613-619
• Gorman, Russell & Connell SD 2009 Land-to-sea connectivity: linking human-derived terrestrial subsidies to subtidal habitat change on open rocky coasts.  Ecological Applications 19: 114-1126

Review:

• Connell, S. D. 2007. Water quality and the loss of coral reefs and kelp forests: alternative states and the influence of fishing. Pages 556-568 in S. D. Connell and B. M. Gillanders, editors. Marine Ecology. Oxford University Press, Melbourne