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Authors: Dr Adriana Verges (UNSW) and A/Prof Thomas Wernberg (UWA).
Ocean warming causes physiological stress in cool water species and facilitates the expansion of warm water species onto temperate reefs. This is leading to range contractions of important cool water organisms such as canopy seaweeds, which fulfil a role similar to trees in forests. These underwater forests provide food and shelter to hundreds of species, and support Australia’s most economically important fisheries, such as rock lobster and abalone.
Increased temperature impacts seaweeds directly and indirectly, e.g. via effects on species that eat them. In Tasmania, warming has been directly linked to a decline in giant kelp forest canopy cover of over 90% since the 1940s. In Western Australia, an extreme heat wave caused the disappearance of several dominant seaweeds over ~ 100 km.
The greatest indirect impacts of warming in seaweed forests are caused by herbivore consumers. As the distribution of warm water herbivores expands, cool water seaweeds that have evolved under low levels of herbivory face increasing herbivore diversity and grazing intensity. In Tasmania, warming has led to the range expansion of a sea urchin that has overgrazed kelp forests. Similarly, increased feeding by tropical and subtropical fishes is increasing herbivore pressure on seaweeds near the warm edge of their distribution.
The climate-mediated loss of seaweeds has reduced the biodiversity of temperate reefs in Tasmania and the Mediterranean, and has been linked to the collapse of commercial fisheries in Japan. Elsewhere in Australia, climate change is emerging as a key threat to algal forests and the species they support.
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Supporting Research
Title
Aims
Bates A. E., Barrett N. S., Stuart-Smith R. D., Holbrook N. J., Thompson P. A. & Edgar G. J. (2014) Resilience and signatures of tropicalization in protected reef fish communities. Nature Clim. Change 4, 62-7.
Analyse the species richness, diversity and functional traits of temperate reef fish communities over 20 years in a global warming hotspot and compare patterns in a marine reserve with nearby sites open to fishing
Booth D. J., Figueira W. F., Gregson M. A., Brown L. & Beretta G. (2007) Occurrence of tropical fishes in temperate southeastern Australia: Role of the East Australian Current. Estuarine, coastal and shelf science 72, 102-14.
Document occurrence of tropical fishes within temperate reefs in the east coast of Australia and evaluate the role of the East Australian Current in facilitating their presence
Booth D. J., Bond N. & Macreadie P. (2011) Detecting range shifts among Australian fishes in response to climate change. Mar Freshw Res 62, 1027-42.
Non-quantitative conceptual review of climate-mediated range shifts in freshwater, estuarine and marine fish
Cheung W. W. L., Meeuwig J. J., Feng M., Harvey E., Lam V. W. Y., Langlois T., Slawinski D., Sun C. & Pauly D. (2012) Climate-change induced tropicalisation of marine communities in Western Australia. Mar Freshw Res 63, 415-27.
Predict current species distributions for 30 tropical, sub-tropical and temperate species that occur along the coast of Western Australia
Feary D. A., Pratchett M. S., J Emslie M., Fowler A. M., Figueira W. F., Luiz O. J., Nakamura Y. & Booth D. J. (In press) Latitudinal shifts in coral reef fishes: why some species do and others do not shift
Review of factors likely to influence latitudinal shifts in tropical fishes, including larval supply, settlement and post-settlement processes
Figueira W. F. & Booth D. J. (2010) Increasing ocean temperatures allow tropical fishes to survive overwinter in temperate waters. Global Change Biol 16, 506-16.
Quantify overwinter survival of tropical fish in SE Australia and evaluate the role of water temperature in facilitating overwintering
Ling S. D. (2008) Range expansion of a habitat-modifying species leads to loss of taxonomic diversity: a new and impoverished reef state. Oecologia 156, 883-94.
Examine the impact of Centrostephanus rodgersii, a range-extending sea urchin, on reef habitat structure and associated biodiversity in Tasmania (Australia)
Ling S. D., Johnson C. R., Frusher S. D. & Ridgway K. R. (2009) Overfishing reduces resilience of kelp beds to climate-driven catastrophic phase shift. Proc Natl Acad Sci USA 106, 22341-5.
To examine whether fishing has reduced kelp bed resilience and thus increased the risk of catastrophic overgrazing by the range-extending urchin C. rodgersii
Nakamura Y., Feary D. A., Kanda M. & Yamaoka K. (2013) Tropical fishes dominate temperate reef fish communities within western Japan. Plos One 8, e81107.
To examine the importance of resource use in structuring the distribution patterns of range shifting tropical and subtropical fishes in temperate reefs within SW Japan
Sala E., Kizilkaya Z., Yildirim D. & Ballesteros E. (2011) Alien marine fishes deplete algal biomass in the eastern Mediterranean. Plos One 6, e17356.
To determine the role of herbivorous fishes on creating a shift from macroalgal dominance to barrens in the eastern Mediterranean
Sen Gupta A., Brown J. N., Jourdain N. C., van Sebille E., Ganachaud A. & Vergés A. (In press) Episodic and non-uniform migration of thermal habitats in a warming ocean. Deep Sea Research Part II: Topical Studies in Oceanography.
To compare the rates of isotherm movement between different ocean regions and at different time scales and to examine to what extent the implied movement is uniform or sporadic.
Serisawa Y., Imoto Z., Ishikawa T. & Ohno M. (2004) Decline of the Ecklonia cava population associated with increased seawater temperatures in Tosa Bay, southern Japan. Fish Sci 70, 189-91.
To assess changes in (i) abundance of the kelp Ecklonia cava, (ii) abalone catches/ generated income and seawater temperature in Tosa Bay (southern Japan) between 1991-2001
Smale D. A. & Wernberg T. (2013) Extreme climatic event drives range contraction of a habitat-forming species. Proceedings of the Royal Society B: Biological Sciences 280.
To document impacts of an extreme marine heat wave on the distribution and abundance of a forest-forming seaweed, and to assess potential long-term changes in reef communities
Vergés A., Tomas F., Cebrian E., Ballesteros E., Kizilkaya Z., Dendrinos P., Karamanlidis A. A., Spiegel D. & Sala E. (2014) Tropical rabbitfish and the deforestation of a warming temperate sea. J Ecol 102, 1518-27.
To determine how tropical rabbitfish abundance is related to sea surface temperature. To relate changes in rabbitfish abundance to benthic community composition and to quantify feeding patterns and preferences of native temperate herbivorous fish vs. invasive tropical rabbitfish.
Wernberg T., Russell B. D., Moore P. J., Ling S. D., Smale D. A., Campbell A., Coleman M. A., Steinberg P. D., Kendrick G. A. & Connell S. D. (2011) Impacts of climate change in a global hotspot for temperate marine biodiversity and ocean warming. J Exp Mar Biol Ecol 400, 7-16.
To review known changes in Australia's temperate reef ecosystems that might have been forced by climate change and variability, and to forecast future change that might be managed by policy
Wernberg T., Russell B. D., Thomsen M. S., Gurgel C. F. D., Bradshaw C. J. A., Poloczanska E. S. & Connell S. D. (2011) Seaweed communities in retreat from ocean warming. Curr Biol 21, 1828-32.
Test for polewards shifts in Australian temperate seaweed floras since 1940's
Wernberg T., Smale D. A., Tuya F., Thomsen M. S., Langlois T. J., de Bettignies T., Bennett S. & Rousseaux C. S. (2013) An extreme climatic event alters marine ecosystem structure in a global biodiversity hotspot. Nature Clim. Change 3, 78-82.
To test the impacts of an extreme marine heat wave on benthic and fish communities in a cool and a warm location.
Wernberg T., Thomsen M. S., Tuya F., Kendrick G. A., Staehr P. A. & Toohey B. D. (2010) Decreasing resilience of kelp beds along a latitudinal temperature gradient: potential implications for a warmer future. Ecol Lett 13, 685-94.
To assess the links between physiological (photosynthesis) and ecological (abundance, recruitment and recovery) performance of the kelp Ecklonia radiata across a temperature gradient
Yamaguchi A. (2010) Biological aspects of herbivorous fishes in the coastal areas of western Japan. Bull Fish. Res. Agen. 32, 89-94.
To quantify the distribution, feeding habits, reproductive behaviour, growth, migration and population strucutre of herbivorous fishes in temperate reefs where seaweed cover has declined
Bates A. E., Pecl G. T., Frusher S., Hobday A. J., Wernberg T., Smale D. A., Sunday J. M., Hill N. A., Dulvy N. K., Colwell R. K., Holbrook N. J., Fulton E. A., Slawinski D., Feng M., Edgar G. J., Radford B. T., Thompson P. A. & Watson R. A. (2014) Defining and observing stages of climate-mediated range shifts in marine systems. Global Environ Change 26, 27-38.
Clarify the processes of range contraction and extension; identify and describe different stages of each
Johnson C. R., Banks S. C., Barrett N. S., Cazassus F., Dunstan P. K., Edgar G. J., Frusher S. D., Gardner C., Haddon M., Helidoniotis F., Hill K. L., Holbrook N. J., Hosie G. W., Last P. R., Ling S. D., Melbourne-Thomas J., Miller K., Pecl G. T., Richardson A. J., Ridgway K. R., Rintoul S. R., Ritz D. A., Ross D. J., Sanderson J. C., Shepherd S. A., Slotvvinski A., Swadling K. M. & Taw N. (2011) Climate change cascades: Shifts in oceanography, species' ranges and subtidal marine community dynamics in eastern Tasmania. J Exp Mar Biol Ecol 400, 17-32.
Compile evidence for impacts of climate change in eastern Tasmania (Australia)
Steneck R. S. & Johnson C. R. (2013) Kelp forests: dynamic patterns, processes and feedbacks. In: Marine Community Ecology (eds M. Bertness, B. Silliman and J. J. Stachowicz) pp. 315-36. Sinaur Associates Inc.
Review of the key patterns and processes that influence the ecosystem and functioning of kelp forest communities
Vergés A., Steinberg P. D., Hay M. E., Poore A. G. B., Campbell A. H., Ballesteros E., Heck K. L., Booth D. J., Coleman M. A., Feary D. A., Figueira W., Langlois T., Marzinelli E. M., Mizerek T., Mumby P. J., Nakamura Y., Roughan M., van Sebille E., Gupta A. S., Smale D. A., Tomas F., Wernberg T. & Wilson S. K. (2014) The tropicalization of temperate marine ecosystems: climate-mediated changes in herbivory and community phase shifts. Proceedings of the Royal Society B: Biological Sciences 281.
Conceptual paper proposing a new type of phase-shift away from macroalgal dominance in temperate reefs and mediated by increased herbivory due to the range expansion and increased feeding rates of tropical/ warm-temperate species
Bennett, S., T. Wernberg, E. S. Harvey, J. Santana-Garcon and B. J. Saunders (2015). Tropical herbivores provide resilience to a climate-mediated phase shift on temperate reefs. Ecology Letters 18(7): 714-723.
Test the effects of herbivores on maintaining a canopy-free state in a tropical-temperate transition zone after a heatwave event that led to complete seaweed canopy loss
Johnson C. R., Banks S. C., Barrett N. S., Cazassus F., Dunstan P. K., Edgar G. J., Frusher S. D., Gardner C., Haddon M., Helidoniotis F., Hill K. L., Holbrook N. J., Hosie G. W., Last P. R., Ling S. D., Melbourne-Thomas J., Miller K., Pecl G. T., Richardson A. J., Ridgway K. R., Rintoul S. R., Ritz D. A., Ross D. J., Sanderson J. C., Shepherd S. A., Slotvvinski A., Swadling K. M. & Taw N. (2011) Climate change cascades: Shifts in oceanography, species' ranges and subtidal marine community dynamics in eastern Tasmania. J Exp Mar Biol Ecol 400, 17-32.
Compile evidence for impacts of climate change in eastern Tasmania (Australia)
Wernberg T., Russell B. D., Moore P. J., Ling S. D., Smale D. A., Campbell A., Coleman M. A., Steinberg P. D., Kendrick G. A. & Connell S. D. (2011) Impacts of climate change in a global hotspot for temperate marine biodiversity and ocean warming. J Exp Mar Biol Ecol 400, 7-16.
To review known changes in Australia's temperate reef ecosystems that might have been forced by climate change and variability, and to forecast future change that might be managed by policy
Basford A. J., Feary D. A., Truong G., Steinberg P. D., Marzinelli E. M. & Vergés A. (2015) Feeding habits of range-shifting herbivores: tropical surgeonfishes in a temperate environment. Mar Freshw Res.
Compare feeding habits of range-shifting tropical herbivorous surgeonfish to warm-termperate species commonly found in temperate reefs
Wernberg T., Russell B. D., Moore P. J., Ling S. D., Smale D. A., Campbell A., Coleman M. A., Steinberg P. D., Kendrick G. A. & Connell S. D. (2011) Impacts of climate change in a global hotspot for temperate marine biodiversity and ocean warming. J Exp Mar Biol Ecol 400, 7-16.
To review known changes in Australia's temperate reef ecosystems that might have been forced by climate change and variability, and to forecast future change that might be managed by policy