Thresholds in seascape connectivity: influence of mobility, habitat distribution, and current strength on fish movement
- 659 Downloads
Assessing connectivity of the marine environment is a fundamental challenge for marine conservation and planning, yet conceptual development in habitat connectivity has been based on terrestrial examples rather than marine ecosystems. Here, we explore differences in marine environments that could affect localized movement of marine organisms and demonstrate the importance of incorporating them into seascape models. We link a fish-based cost surface model to simulated seascapes to test hypotheses about the effects of fish mobility, water current strength, and their interactions on functional connectivity of a seascape. Our models predict that sedentary fish should be more sensitive to habitat change than more mobile fish. Furthermore, highly mobile fish should be more sensitive to water currents than habitat change. In our models, the cost of swimming against a current (of any strength) exceeded its benefits, resulting in overall decreases in connectivity with increasing current strengths. We further hypothesized that thresholds in functional connectivity will be affected by both fish mobility and water current strength. Connectivity thresholds in the models occurred when 10–50 % of benthic habitat was favourable; below these thresholds there was a rapid increase in path cost. Thresholds were influenced by the interaction of relative habitat costs (simulated fish mobility) and habitat fragmentation: thresholds for less mobile fish (higher relative cost) were reached at lower habitat abundance when habitat was fragmented, while thresholds for mobile fish were less affected by fragmentation. Our approach suggests mobility and water current are useful indicators of connectivity in marine environments and should be incorporated in seascape models.
KeywordsHabitat abundance Habitat loss Fragmentation Conservation Marine Landscape Damselfish
This is a contribution from Project Seahorse. IRC was supported by the Natural Sciences and Engineering Research Council of Canada, IODE Canada, and the Animal Behavior Society. SEG was supported by a Natural Sciences and Engineering Council of Canada Discovery Grant. Project Seahorse is supported by Guylian Chocolates (Belgium) and the John G. Shedd Aquarium, through partnerships in marine conservation. The manuscript was greatly improved by comments from A. Vincent, P. P. Molloy, A. R. E. Sinclair, I. Côté, and S. Hinch.
- Bélisle M, St. Clair CC (2002) Cumulative effects of barriers on the movements of forest birds. Conserv Ecol 5:9 (Available from http://www.ecologyandsociety.org/vol5/iss2/art9/)
- Foley MM, Halpern BS, Micheli F, Armsby MH, Caldwell MR, Crain CM, Prahler E, Rohr N, Sivas D, Beck MW, Carr MH, Crowder LB, Duffy JE, Hacker SD, McLeod KL, Palumbi SR, Peterson CH, Regan HM, Ruckelshaus MH, Sandifer PA, Steneck RS (2010) Guiding ecological principles for marine spatial planning. Mar Policy 34:955–966CrossRefGoogle Scholar
- Froese R, Pauly D (2012) FishBase. Available from http://www.fishbase.org. Accessed Feb 2012
- Grober-Dunsmore R, Pittman SJ, Caldow C, Kendall MS, Frazer TK (2009) A landscape ecology approach for the study of ecological connectivity across tropical marine seascapes. In: Nagelkerken I (ed) Ecological connectivity among tropical coastal ecosystems. Springer, Dordrecht, pp 493–530CrossRefGoogle Scholar
- IUCN (2012) The IUCN red list of threatened species. Available from http://www.iucnredlist.org. Accessed June 2012
- Lindsay CC (1978) Form, function, and locomotory habits in fish. In: Hoar WS, Randall DJ (eds) Fish physiology, vol VII: Locomotion. Academic Press, New York, pp 1–88Google Scholar
- Robinson J, Aumeeruddy R, Jorgensen TL, Ohman MC (2008) Dynamics of camouflage (Epinephelus polyphekadion) and brown marbled grouper (Epinephelus fuscoguttatus) spawning aggregations at a remote reef site, Seychelles. Bull Mar Sci 83:415–431Google Scholar
- Waycott M, Duarte CM, Carruthers TJB, Orth RJ, Dennison WC, Olyarnik S, Calladine A, Fourqurean JW, Heck KL, Hughes AR, Kendrick GA, Judson KW, Short FT, Williams SL (2009) Accelerating loss of seagrasses across the globe threatens coastal ecosystems. Proc Natl Acad Sci USA 106:12377–12381PubMedCrossRefGoogle Scholar