Click Here to download Dr. Bergmann's thesis dissertation. It is approximately 1.5 MB.
Abstract
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 outcompete
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.