Other current projects
Ocean acidification and the macro algal environment
Abstract: Approximately one third of anthropogenic carbon emissions are absorbed by the oceans. It remains uncertain how rapid increases in ocean acidification will affect coastal ecosystems, specifically the mid intertidal to the shallow subtidal zones. This is where a common brown alga called Fucus distichus occurs. This phaeophyte alternates between haploid and diploid generations. Gametes are released from the rounded and inflated receptacles. Our hypothesis was based on the effects of increased ocean acidification. By exposing F. distichus eggs and zygotes to waters infused with carbon dioxide gas and placing them into an enclosed chamber with a steady flow of CO2 gas, an acidic equilibrium was established. We then measured the effects of the increased CO2. By counting the number of zygotes that germinated and measuring the length of rhizoids during early development, we were able to determine how an acidified ocean environment might affect algal development and growth.
Blooms of green macroalgae occur worldwide but are most common in temperate latitudes. They arise as a result of increased nutrients often termed eutrophication. Although it would seem that an increase in nutrients would be a positive condition, algal blooms are generally detrimental (Peterson et al., 1994; Fletcher, 1996; Valiela et al., 1997; Rafaelli et al., 1998; Cummins et al., 2004). One of the dominant components of subtidal blooms is the green alga Ulvaria obscura. It is a unique macro algae because it releases dopamine into the surrounding water (Van Alstyne et al., submitted). It is not clear if U. obscura releases this catecholamine as a feeding deterrent or under stressful conditions. We tested the combined effects of dopamine and ocean acidification on the brown alga Fucus distichus.
Dopamine functions as a neurotransmitter and hormone in animals. In plants its applications are less understood. Dopamine is a member of a family of compounds called catecholamines ,which also include epinephrine (adrenalin) and norepinephrine. Ulvaria obscura is the only alga known to produce dopamine in concentrations of approximately 0.5-1% of the alga’s fresh mass (Van Alstyne et al., submitted). The release of dopamine into intertidal and shallow subtidal zones could be detrimental to co-occurring organisms. It has been hypothesized that the alga releases this compound under stressful conditions and to ward off herbivores in a form of chemical defense (Van Alstyne et al., 2006). Harmful algal blooms (HAB’s) impose physical and chemical changes to the marine environment. Bloom species can outcompeting co-occurring algae (Piazzi et al., 2001), disrupting water flow (Escartin and Aubrey, 1995), and deplete nutrients and oxygen (Hull, 1987; Franz and Friedman, 2002).
