TY - JOUR

T1 - Disturbance alters ecosystem engineering by a canopy-forming alga

AU - Pocklington, Jacqueline

AU - Jenkins, Stuart

AU - Bellgrove, Alecia

AU - Keough, Michael

AU - O'Hara, Tom

AU - Masterson Algar, Patricia

AU - Hawkins, Stephen J.

PY - 2018/6

Y1 - 2018/6

N2 - Canopy-forming fucoid algae have an important role as ecosystem engineers on rocky intertidal shores, where they increase the abundance of species otherwise limited by exposure during low tide. The facilitative relationship between Ascophyllumnodosum and associated organisms was explored using a frond breakage experiment (100%, 50%, 25%, 0% intact-frond treatments) in southern England, to assess the consequences of disturbance. Understorey substratum temperature was on average38C higher in 0% and 25% intact-frond treatments than in plots with 50% and 100% intact fronds. Light (as PAR during low tide) doubled in 0% intact-frond treatments in comparison to other treatments (which had similar light levels). Mobile invertebratespecies richness declined by on average 1 species per m2 in the treatments with only 25% and 0% intact fronds, and the abundance of Littorina obtusata declined by 2.4–4.2 individuals per m2 in the treatments with 25 and 0% intact fronds.Sessile taxa, including Osmundea pinnatifida and encrusting coralline algae, declined by half on average in the 0% intactfrond treatment. These results suggest that the ability of Ascophyllum to mediate environmental conditions to the understoreyis the mechanism responsible for species distributed in the understorey (autogenic ecosystem engineering). The results of this study imply that a pulse disturbance resulting in a 50% breakage of Ascophyllum fronds significantly increasestemperature and decreases the abundance of mobile invertebrates usually associated with Ascophyllum. Sessile taxa associated with Ascophyllum can, however, withstand disturbances down to 25% intact Ascophyllum fronds.

AB - Canopy-forming fucoid algae have an important role as ecosystem engineers on rocky intertidal shores, where they increase the abundance of species otherwise limited by exposure during low tide. The facilitative relationship between Ascophyllumnodosum and associated organisms was explored using a frond breakage experiment (100%, 50%, 25%, 0% intact-frond treatments) in southern England, to assess the consequences of disturbance. Understorey substratum temperature was on average38C higher in 0% and 25% intact-frond treatments than in plots with 50% and 100% intact fronds. Light (as PAR during low tide) doubled in 0% intact-frond treatments in comparison to other treatments (which had similar light levels). Mobile invertebratespecies richness declined by on average 1 species per m2 in the treatments with only 25% and 0% intact fronds, and the abundance of Littorina obtusata declined by 2.4–4.2 individuals per m2 in the treatments with 25 and 0% intact fronds.Sessile taxa, including Osmundea pinnatifida and encrusting coralline algae, declined by half on average in the 0% intactfrond treatment. These results suggest that the ability of Ascophyllum to mediate environmental conditions to the understoreyis the mechanism responsible for species distributed in the understorey (autogenic ecosystem engineering). The results of this study imply that a pulse disturbance resulting in a 50% breakage of Ascophyllum fronds significantly increasestemperature and decreases the abundance of mobile invertebrates usually associated with Ascophyllum. Sessile taxa associated with Ascophyllum can, however, withstand disturbances down to 25% intact Ascophyllum fronds.

KW - Ascophyllum nodosum

KW - Community

KW - Facilitation

KW - Foundation species

KW - Macroalgae

KW - Marine

KW - Intertidal

U2 - 10.1017/S0025315416002009

DO - 10.1017/S0025315416002009

M3 - Article

VL - 98

SP - 687

EP - 698

JO - Journal of the Marine Biological Association of the United Kingdom

JF - Journal of the Marine Biological Association of the United Kingdom

SN - 0025-3154

IS - 4

ER -