| Phytoplankton not only form the base of the oceanic food web, but also act as mediators for a majority of biogeochemical fluxes in aquatic environments. Their functional importance in all natural waters, and especially in coastal areas, is paramount. Consequently much research has concentrated on the physiology, primary production, and distribution of coastal phytoplankton groups. Unfortunately, much of this work has focused on a few major phytoplankton groups while many other taxa of potential significance have been overlooked. One such overlooked group of coastal phytoplankton are the cryptomonads. This thesis clarifies our understanding of the physiological ecology of the Cryptomonads and thus serves as the basis for understanding and forecasting the stability and resilience of coastal ecosystems.; Cryptophytes have an exclusive combination of photosynthetic pigments and, under low light conditions, the ability to mixotrophically exploit available inorganic as well as organic nutrients. This makes them a unique group able to take advantage of several niches in the coastal environment. Specifically, cryptophytes are able to maximize light absorption and utilization by varying pigments concentrations and PSII:PSI stoichiometry, to use alternative fuel sources such as organic nutrients under low light conditions when photosynthetic rates may not be sufficient to support strictly autotrophic growth, and to use their swimming ability to control their proximity to light and nutrients in the water column. These distinctive strategies allow cryptophytes to rival more customary bloom forming algae under certain conditions. Principally, cryptophytes are most prevalent in areas marked by low light and high concentrations of organic matter. In these areas, their physiological capabilities allow them to potentially out-compete traditional phytoplankton groups. As more coastal areas move towards these types of organically laden, low light environments we should expect to see a proliferation of cryptophyte algae as they exploit their lifestyle to contest other coastal phytoplankton. In order to comprehend the changes this shift in phytoplankton community composition will have on coastal ecosystems, it is essential to understand the current physiological ecology and distribution patterns of cryptophyte algae. This work begins to illuminate the functional importance of cryptophyte algae in coastal areas. |
