Interactive responses of primary producers and grazers to pollution on temperate rocky reefs. (June 2018)

• Record Type: Journal Article
• Authors: Fowles, Amelia E.; Stuart-Smith, Rick D.; Hill, Nicole A.; Thomson, Russell J.; Strain, Elisabeth M.A.; Alexander, Timothy J.; Kirkpatrick, James; Edgar, Graham J.
• Is Part Of: Environmental pollution. Volume 237(2018)
• Page Start: 388
• Page End: 395
• Publication Date: 2018-06
• Subjects: Epifauna -- Herbivory -- Aquaculture -- Kelp -- Invertebrates; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2018.02.061
• Languages: English
• ISSNs: 0269-7491

Abstract

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. Graphical abstract: Image 1 Highlights: Common urban pollution sources directly impacted macroalgae in experimental plots. Indirect effects of pollution through herbivorous invertebrates were not observed. Pollution and complex macroalgae drive small grazing invertebrate abundance. Large gazing invertebrates such as sea urchins were more pollution tolerant. Abstract : Impacts of common marine pollution sources on macroalgal beds were primarily direct rather than mediated by indirect interactions involving invertebrate grazers.