Macroalgal Ecology

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Sargassum muticum.jpg
A canopy of fucoid algae is a defining characteristic of sheltered rocky shores. These canopy-forming algae act as foundation species, creating habitat and modulating the flow of resources to other organisms- they are effectively reefs. One striking example that the Marine Ecology and Technology group are actively working on, is Ascophyllum nodosum, a mid-shore dominant alga along sheltered coasts of the North Atlantic. Ascophyllum canopies can have a high biomass and influence biodiversity by providing a stable, year-round, canopy which facilitates understory algae. This species is relatively long lived, with estimated holdfast ages exceeding 50 years and is considered to be well protected from grazers by the metabolite, phlorotannin with typical concentrations of 5-10 % dry weight. Since 2001, we have been researching the ecology of Ascophyllum, with particular focus on long-term temporal dynamics, and their chemical defence.

Chemical defences consisting of both primary and secondary metabolites are found in many macroalgae, with their primary function appearing to be as a grazing deterrent. In recent years, we have been investigating the role that phlorotannins play in the ecology of two canopy forming macroalgae; Ascophyllum and Sargassum muticum. Whilst Ascophyllum is a text-book example of an important foundation species commonly found on sheltered shores throughout the North Atlantic, Sargassum is a Japanese macroalga that is a highly successful invader of the Western European rocky shores. It was first observed in the UK on the Isle of Wight in 1973 and has spread rapidly throughout the coastline, reaching Northern Ireland in 1995, south-west Wales in 1997 and Loch Ryan in Scotland in 2004. Sargassum also produces a conopy, but unlike Ascophyllum, this canopy is not stable- breaking down in Autumn leaving only a perennial hold-fast and one or two stipes. The Sargassum canopy, therefore, does not provide the continuous, stable habitat that does Ascophyllum. Of current interest are the differences in ecologies between the two species, and specifically how Britain’s local grazers are responding to the Sargassum invasion, particularly since Sargassum is also unpalatable to grazers, but has phlorotannin concentrations around one order of magnitude lower than Ascophyllum.

[edit] For further information contact

Martyn Kurr,
School of Ocean Sciences,
University of Wales Bangor,
Menai Bridge,
Anglesey,
LL59 5AB,

ospe11@bangor.ac.uk

Martyn was awarded a NERC studentship in 2011.

[edit] Key references from our lab

Wadke, P. M., Burrows, M. T., Meldrum, D., & Davies, A. J. (2007). Using magneto-resistive sensors to monitor animal behaviour: a case study using limpets (pp. 1–6). IEEE. doi:10.1109/OCEANS.2007.4449334

Davies, A. J., & Johnson, M. P. (2006). Coastline configuration disrupts the effects of large-scale climatic forcing, leading to divergent temporal trends in wave exposure. Estuarine, Coastal and Shelf Science, 69(3-4), 643–648. doi:10.1016/j.ecss.2006.05.012

Davies, A., Johnson, M., & Maggs, C. (2008). Subsidy by Ascophyllum nodosum increases growth rate and survivorship of Patella vulgata. Marine Ecology Progress Series, 366, 43–48. doi:10.3354/meps07453

Mineur, F., Davies, A. J., Maggs, C. A., Verlaque, M., & Johnson, M. P. (2010). Fronts, jumps and secondary introductions suggested as different invasion patterns in marine species, with an increase in spread rates over time. Proceedings of the Royal Society B: Biological Sciences, 277(1694), 2693–2701. doi:10.1098/rspb.2010.0494

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