Annemie Rose Janssen1,2, Mariana Mayer-Pinto2, Melanie Bishop1, Jessica O’Hare1, Adam Stow1, Katherine Dafforn1
1Macquarie University, Australia - 2University of New South Wales, Australia
Marine ecosystems are increasingly threatened by the combined effects of climate warming and coastal development. Many of these ecosystems are underpinned by habitat-forming species whose adaptive capacity is dependent on genetic diversity within their populations. However, in urbanised estuaries where ecosystems have been exposed to centuries of human activity, the genetic diversity of habitat-formers may already be eroded, limiting their adaptive potential and undermining their role in maintaining ecosystem structure and function. In this study, we characterised the genetic diversity and population structure of the golden kelp, Ecklonia radiata, the main habitat-former in temperate Australia, across eight sites within Sydney Harbour, an urban estuary located in Australia’s largest city. We hypothesised that genetic diversity would be greater at outer harbour sites, that are regularly flushed by coastal waters, than at inner harbour sites which are generally regarded as more degraded. Our analysis of 2,107 neutral single-nucleotide polymorphisms (SNPs) revealed the presence of two genetic clusters – corresponding to the inner and outer harbour sites – each with small effective population sizes. Both populations presented relatively low genetic diversity and elevated inbreeding coefficients, suggesting high rates of self-fertilisation across the harbour. The strong population structure was underpinned by significant associations with morphological patterns of E. radiata and environmental differences between the inner and outer harbour. Genotype-environment analyses revealed strong associations with light, organic matter, copper, manganese and temperature suggesting adaptation to local environments. These findings emphasise the importance of considering local adaptation and population structure in developing conservation strategies for populations of habitat-forming species, particularly in heavily urbanised environments.
Biography
Annemie Rose has a background in marine ecology and international environmental policy. Her research has spanned deep-sea sharks, marine mammals, Southern Ocean dynamics, and kelp. She has engaged in the ongoing dialogue between scientists, governments, industry leaders, and high-level authorities like the EU Parliament and UNESCO’s Intergovernmental Oceanographic Commission. Today, her lab coat smells like seaweed, her hair is saltwater-damaged, but she feels like a phycological Indiana Jones.