Interactive responses of primary producers and grazers to pollution on temperate rocky reefs

Amelia E Fowles; Rick D Stuart-Smith; Nicole A Hill; Russell J Thomson; Elisabeth M A Strain; Timothy J Alexander; James Kirkpatrick; Graham J Edgar

doi:10.1016/j.envpol.2018.02.061

Interactive responses of primary producers and grazers to pollution on temperate rocky reefs

Environ Pollut. 2018 Jun:237:388-395. doi: 10.1016/j.envpol.2018.02.061. Epub 2018 Mar 15.

Authors

Amelia E Fowles¹, Rick D Stuart-Smith², Nicole A Hill¹, Russell J Thomson³, Elisabeth M A Strain⁴, Timothy J Alexander⁵, James Kirkpatrick⁶, Graham J Edgar¹

Affiliations

¹ Institute for Marine and Antarctic Studies, University of Tasmania, Private Bag 49, Hobart, Tasmania, 7001, Australia.
² Institute for Marine and Antarctic Studies, University of Tasmania, Private Bag 49, Hobart, Tasmania, 7001, Australia. Electronic address: rstuarts@utas.edu.au.
³ Centre for Research in Mathematics, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia.
⁴ Institute for Marine and Antarctic Studies, University of Tasmania, Private Bag 49, Hobart, Tasmania, 7001, Australia; Sydney Institute of Marine Science, Chowder Bay, Mosman, NSW, 2068, Australia.
⁵ Department of Fish Ecology and Evolution, Centre of Ecology, Evolution and Biogeochemistry, EAWAG Swiss Federal Institute of Aquatic Science and Technology, Seestrasse 79, CH-6047, Kastanienbaum, Switzerland; Division of Aquatic Ecology and Evolution, Institute of Ecology and Evolution, University of Bern, Baltzerstrasse 6, CH-3012, Bern, Switzerland.
⁶ Discipline of Geography and Spatial Sciences, School of Land and Food, University of Tasmania, Private Bag 77, Hobart, Tas, 7001, Australia.

PMID: 29502001
DOI: 10.1016/j.envpol.2018.02.061

Abstract

Macroalgal beds provide important habitat structure and support primary production for rocky reef communities, but are increasingly degraded as a result of human pressures. Various sources of pollution can have both direct and interactive effects on stressed ecosystems. In particular, interactions involving invertebrate grazers could potentially weaken or strengthen the overall impact of pollution on macroalgal beds. Using a paired impact-control experimental design, we tested the effects of multiple pollution sources (fish farms, marinas, sewerage, and stormwater) on translocated and locally established algal assemblages, while also considering the influence of invertebrate grazers. Marinas directly affected algal assemblages and also reduced densities of amphipods and other invertebrate mesograzers. Fish farms and sewerage outfalls tended to directly increase local establishment of foliose and leathery algae without any indication of changes in herbivory. Overall, pollution impacts on algae did not appear to be strongly mediated by changes in grazer abundance. Instead, mesograzer abundance was closely linked to availability of more complex algal forms, with populations likely to decline concurrently with loss of complex algal habitats. Macrograzers, such as sea urchins, showed no signs of a negative impact from any pollution source; hence, the influence of this group on algal dynamics is probably persistent and independent of moderate pollution levels, potentially adding to the direct impacts of pollution on algal beds in urbanised environments.

Keywords: Aquaculture; Epifauna; Herbivory; Invertebrates; Kelp.

MeSH terms

Animals
Ecosystem*
Environmental Monitoring*
Environmental Pollution
Feeding Behavior
Herbivory
Invertebrates / physiology*
Sea Urchins