R.J. Veenhof1, C. Champion2, S.A Dworjanyn1, M.A. Coleman1,2
1National Marine Science Centre, Southern Cross University, Coffs Harbour, NSW, Australia
2Department of Primary Industries, Fisheries, Coffs Harbour, NSW, Australia
Kelp forests are biodiverse habitats that provide vast ecosystem goods and services but are in decline due to a range of anthropogenic stressors. Ocean warming is driving the transition of kelp forests to alternative states like urchin barrens and algal turfs, resulting in dramatic declines in biodiversity. To mitigate such profound ecosystem changes, an understanding of the ecology of kelp across all life cycle stages necessary. Kelps have a heteromorphic alternation of generations, and while there is growing understanding of the mechanisms driving change in the macroscopic sporophyte stage, the ecology of the microscopic gametophyte stage remains a knowledge gap. Here we give an overview of some of the most pressing questions concerning gametophytes, and present some of our research starting to fill these gaps. Of particular importance are biotic interactions of gametophytes with grazers, which may be a mechanism limiting reversal from barren and turf states to kelp forests. We show that several micro-grazers can negatively impact gametophyte persistence but also facilitate their reproduction. Warming appears to have little impact on herbivore grazing, but does hamper gametophyte recovery from grazing and their ability to recruit into sporophytes. These findings show the complexity of ecological interactions of kelp microscopic stages and beg further research on the ecological functioning of kelp gametophytes under climate change.