Luka Wright1,2, Louise Kregting1, Taylor Simpkins2, Belinda Martin2, Karen Filbee-Dexter2, 3, Thomas Wernberg2, 3
1Queen’s University Marine Laboratory, The Strand, Portaferry, Northern Ireland, United Kingdom,2Oceans Institute, University of Western Australia, Perth, Western Australia, Australia, 3Institute of Marine Research, His, Agder, Norway.
Kelp forests are the most productive macroalgal biome on the planet. Most of their primary production is remineralised in the forest or exported. Longevity of the exported fraction is partially explained by extrinsic factors like light, temperature and oxygen. But even under identical environmental conditions, warmer-affinity and annual plants decompose faster due to poorly understood intrinsic drivers. Data on microbial community succession indicate that microbes may play an important part in kelp remineralisation. However, due to microbial ecology’s increasing focus on omics approaches, saprotrophic function has not been directly quantified on kelp. Here we examine data from kelp forests in both hemispheres to understand the onset of microbial kelp decomposition. We resurrected an all but forgotten method to measure microbial extracellular enzyme activity on environmental samples. Our generalised additive multilevel models suggest that saprotrophic activity follows a boom-bust pattern with a peak after 40 days of in situ decomposition in most species with a potential earlier peak before 20 days. In vitro decomposition at varying temperature moreover shows that the initial peak is 14 days early (20°C, 25°C) and more pronounced (25°C) under warmer conditions compared to the cool treatment (15°C). Our results provide a first insight into the temporal patterns of saprotrophic kelp breakdown and reveal a mechanistic driver behind the known temperature effect on decomposition.
Biography:
I was born in Munich and after finishing secondary school there with a six-month stint in Adelaide, I travelled through Southeast Asia for the large part of ten months to work with marine conservation NGOs. I then discovered kelp forests while studying marine ecology in Plymouth. After some time working on Irish kelp forests in Strangford Lough, I secured my PhD with the Wernberg laboratory at UWA.
