Ecology of antifouling resistance in the bladder wrack Fucus vesiculosus: patterns of microfouling and antimicrobial protection

Abstract

The impact of moderate environmental stress may be modulated by stress-induced shifts of biotic interactions such as host -epibiont relationships. We studied the stress regime in shallow Western Baltic habitats, the variability of fouling at different temporal and spatial scales, and whether common stressors -low light, high temperature and grazing -affect the abundance and composition of the biofilm on a regionally important macroalga, the bladder wrack Fucus vesiculosus. We further explored the alga's capacity to chemically modulate the recruitment of microfoulers and analyzed whether this ability is impacted by stress. In laboratory, mesocosm and field experiments, fouling pressure and epibiotic cover on the alga varied strongly with changing environmental conditions such as temperature, irradiance, depth and grazing. The expectation that abiotic stress affects the fouling-modulating ability of the alga and thus indirectly produces the observed variability of epibiosis was not generally confirmed. Indeed, while the strength of chemical antifouling resistance varied seasonally, with a maximum in winter-spring and a minimum in late summer, this could not be related to temporal patterns of environmental stress, fouling pressure, or growth of F. vesiculosus. Only the seasonal variation in reproduction seemed to be in phase with antifouling activity. Controlled experiments confirmed that resistance strength was not affected by temperature or grazing, and only moderately by light. We conclude that the fouling modulation ability of F. vesiculosus may suffer from light reduction (e.g. by eutrophication effects), but is not sensitive to predicted warming or enhanced grazing.

Modeling the effects of abiotic and biotic factors on the depth distribution of Fucus vesiculosus in the Baltic Sea

“…Data from shallower depths (Strömgren 1986, Wahl et al 2010 agree with the year-round pattern of modeled μ c in showing a peak between May and June, which follows a steep increase in the spring months and is followed by a more gradual decline during summer. The modeled μ c at z L , with minima in early spring and autumn, disagrees with observed growth rates that show 1 clear minimum in winter.…”

Sour times: seawater acidification effects on growth, feeding behaviour and acid–base status of Asterias rubens and Carcinus maenas

“…Because the benthic habitat of sea stars, especially in eutrophic coastal zones, is often an area of high decomposition, the CO 2 levels in these regions are often substantially higher than in the pelagic environment (Feely et al 2008, Melzner et al 2009, Thomsen et al 2010). The mean pH at 10 m depth in Kiel Fjord was 7.7 (± 0.2 SD, corresponding to a pCO 2 of ~1400 µatm) between May and October 2009 (Wahl et al 2010) and was probably periodically lower at the sediment -water interface (see also Thomsen et al 2010). Consistent with our findings, Gooding et al (2009) report that the sea star Pisaster ochraceus grew significantly better and tended to consume more mussels under intermediate acidification levels (780 µatm), which, however, were closer to our natural 'low' than to our intermediate level.…”

Temperature tolerance of western Baltic Sea Fucus vesiculosus – growth, photosynthesis and survival

“…In the western Baltic Sea shallow water temperature may reach more than 30°C for short periods during summer (Wahl et al, 2010). These heatwaves are predicted to become more frequent and intense due to global warming.…”