Dr Jacqui Pocklington1, Dr Timothy O’Hara, Professor Michael Keough, Emeritus Professor Stephen Hawkins, Professor Stuart Jenkins, Dr Alecia Bellgrove
1Deakin University, Geelong, Australia
Intertidal macroalgal canopies are important autogenic ecosystem engineers on temperate rocky shores. The effect of habitat complexity on the distribution patterns of macroinvertebrates was investigated in two regions (Southern England, South-Eastern Australia) to examine whether it explains variation in macroinvertebrate abundance that could be incorrectly attributed as association with an intertidal algal canopy. The microhabitats occupied by macroinvertebrates within and outside the canopy were also identified to examine whether features of the algae or the substratum affect patterns in distribution.
Six species had abundances that varied in relation to indices of substratum complexity on one or more sampling days at two sites in South-Eastern Australia, no pattern was consistent for any species through time. No species varied in response to substratum complexity at Hannafore Point in Southern England.
Macroinvertebrates occupied a variety of microhabitats within the canopy including algal fronds and holdfasts, crevices and small pits in the rock surface, vertical and horizontal bare rock. Despite the availability of abiotic microhabitats (e.g. crevices, small pits) within and outside the canopy, no macroinvertebrate associated with the canopy occupied an alternative abiotic microhabitat where the canopy was absent. Some species consistently occupied the same microhabitats across shores; though ‘functionally equivalent’ species did not consistently occupy particular microhabitats (e.g. not all periwinkles occupied the same microhabitats). The findings of this study confirm that intertidal macroalgal canopies are a major determining factor in the distribution of invertebrates on temperate rocky shores, and microhabitats are less important for species distribution in their presence.
Presentation Slides – Jacqui Pocklington
Biography:
Dr Jacqui Pocklington is a marine ecologist who’s research focuses on temperate reefs, macroalgae, invertebrates, monitoring, citizen science and conservation. She’s worked in academia, non-profit, consultancy and state government.
