Oral Presentation Australian Society for Fish Biology Conference 2017

Habitat connectivity exerts opposing effects on piscivory and browsing (#115)

Tyson SH Martin 1 , Asier BH Olalde 2 , Andrew D Olds 3 , Charlotte Berkstrom 2 , Ben L Gilby 3 , Thomas A Schlacher 3 , Ian R Butler 4 5 , Nicholas A Yabsley 3 , Rod M Connolly 1
  1. Australian Rivers Institute – Coast and Estuaries, and School of Environment, Griffith University, Southport, Queensland, Australia
  2. Department of Ecology, Environment & Plant Sciences, Stockholm University, Stockholm, Sweden
  3. School of Science and Engineering, University of the Sunshine Coast, Maroochydore, Queensland, Australia
  4. Research School of Biology, The Australian National University, Canberra, Australian Capital Territory, Australia
  5. CoraLogic, CoraLogic Environmental Consulting, Cook, Australian Capital Territory, Australia

Context Connectivity is an important property of landscapes that shapes populations and ecosystem functioning. We do not know, however, whether and how different types of spatial linkages influence ecological functions, and this hampers the integration of connectivity into conservation plans.

Objectives We used coral reef seascapes in eastern Australia as a model system to test whether habitat connections (between reefs) and seascape connections (among reefs and other habitats) exert similar effects on two key ecological functions (piscivory and browsing).

Methods We measured browsing (on macroalgae) and piscivory (on live prey fish) rates on reefs that differed in their level of connectivity to both other reefs and nearby mangroves and seagrass in Queensland, Australia.

Results The extent of habitat connectivity between reefs significantly influenced ecological function, but it did so in asymmetrical ways: isolated reefs supported high browsing but low piscivory, whilst, conversely, reefs that were closer to other reefs supported high piscivory but low browsing. This was not caused by browsers avoiding their predators, as the dominant piscivores (small predatory snappers) were too small to consume the dominant browsers (large rabbitfishes). Seascape features (e.g. distance to mangroves or seagrass) were less important in shaping function on reefs in this system.

Conclusions The way connectivity shapes ecological functions likely depends on both the type of spatial linkage and the type of ecological function in question. This has implications for conservation planning seeking to incorporate connectivity.