A/Prof. Melanie Bishop1, Dr Mariana Mayer-Pinto2, Dr Maria Vozzo3, Ms Gemma Clifton1, A/Prof Katherine Dafforn1
1School of Natural Sciences, Macquarie University, North Ryde, Australia, 2School of Biological, Earth and Environmental Sciences, University of NSW, Kenningston, Australia, 3Sydney Institute of Marine Science, Mosman, Australia
The construction boom underway in our seas is contributing to a loss of biodiversity. Built structures typically have flat and smooth surfaces that provide little protection against predation and environmental stressors, and provide a relatively homogenous environment for colonisation. Eco-engineering seeks to redress this issue by incorporating habitat complexity into built structures. The assumption is a universally positive habitat complexity-biodiversity relationship, though there are few tests of whether this indeed holds up across environmental gradients, particularly on built structures. Here, we assessed how the enhancement of habitat complexity on seawalls affects biodiversity across two environmental gradients: an intertidal elevation gradient (i.e. high, mid and low intertidal), and a salinity gradient within an estuary (i.e. upstream vs downstream). Across the intertidal elevation gradient, we found effects of complexity generally increased with temperature and desiccation stress. At high and mid intertidal elevations, where complexity strongly mitigated temperature extremes, we found strong effects of complexity on biodiversity. However, at low intertidal elevations, where temperature maxima were less extreme, we found generally neutral effects. Across the estuarine gradient, effects of complexity generally decreased with distance upstream, perhaps reflecting the diminishing species pool of available colonists. Our results reinforce the need to consider key stressors to organisms and the niches of target species when designing eco-engineering interventions. Eco-engineering that is blindly applied using a one-size-fits-all approach may otherwise serve as little more than greenwashing.
Presentation Slides – Melanie Bishop
Biography:
A/Prof Bishop is a coastal ecologist with over 15 years of experience. She leads a team at Macquarie University that is uncovering how coastal ecosystems operate and respond to change. Her research has a particular focus on the innovation and evaluation of environmental solutions that create habitat and conserve native biodiversity in degraded seascapes. She co-leads the green engineering working group of the World Harbour Project and the Living Seawalls Program. The impact A/Prof Bishop’s work on environmental management has been recognised with a NSW Scientist of the Year Award, and the Brian Robinson Fellowship from the Banksia Environmental Foundation.
