Preparing a Tropical Synechococcus sp. for a Warming Ocean with Human-Assisted Evolution
Human Assisted Evolution
Many marine organisms are struggling to adapt to the ocean’s rapidly increasing sea surface temperatures as a result of high levels of anthropogenic carbon dioxide. The coral reef ecosystem, for example, suffers from large population declines due to coral bleaching events. Corals become stressed from the high temperature of their environment and, as a consequence, expel the symbiotic algae that inhabit their tissue, losing their main source of food. The corals then become a bleach white color and essentially starve to death. Losing the coral reef ecosystem would have major consequences to the surrounding environment and to ourselves. Thus, researchers have come up with a tool to help corals evolve faster and keep up with the rapidly increasing temperature of their environment, human-assisted evolution. I have previous experience with human-assisted evolution during the time I spent interning for the Gates Lab at the Hawai’i Institute of Marine Biology. We took calcifying species of coral (typically Montipora) that have survived past bleaching events and artificially bred them to create offspring with thermally tolerant genes. After each generation, the coral offspring became more thermally tolerant than the generation before. Although this method is effective for creating thermally tolerant corals, the reproduction rate and growth rate of corals is long. In addition, the scientific community has not reacted to the decline in coral populations fast enough, resulting in a race to save the coral population before they become extinct. I have taken inspiration from this experience to create a similar study with the cyanobacteria (picoprokaryotic phytoplankton) Synechococcus sp. collected from the Waterbury lab at the Woods Hole Oceanographic Institution. With the ocean continuing to increase in SST, the phytoplankton community is bound to shift as well; in particular, the survivability of picoprokaryotic phytoplankton in the tropics/subtropics is questionable. To prevent a last minute rush to save the phytoplankton community — like what is currently going on with the coral community — I plan to test methods of human-assisted evolution on the cyanobacteria Synechococcus sp.. I will select thermally tolerant traits in the Synechococcus sp. through human-assisted evolution. The methods behind human-assisted evolution are sound and well-established, however, there have been little to no record of human-assisted evolution on phytoplankton. If the study is a success, researchers can continue to develop and test different species of phytoplankton for thermal tolerance in hope of creating colonies of phytoplankton that are well adapted to future ocean environments.
Importance of Picoplankton
Picoplankton play an important role, especially in the tropical and subtropical ocean ecosystems. The tropical/subtropical ecosystems are oligotrophic — meaning they are nutrient poor — thus primary productivity is relatively low. This stresses the importance of picoplankton as one of the tropics/subtropics only major sources of primary production. According to Grossman and colleagues, picoplankton contribute roughly ~26–56% of the global phytoplankton biomass and about half of the global ocean primary productivity (Grossman et al., 2010). If the picoplankton community were to be removed from the ecosystem through thermal intolerance, the tropical/subtropical pelagic ecosystem would experience major declines in primary productivity and marine biomass; possibly ending in a total ecosystem collapse through a bottom up trophic level cascade.
The Future
For the future, if this study is successful, researchers will be able to apply this data into population dynamics, oceanographic projections, and species preservation. (1) Species Preservation: most notably, this study is meant to preserve the group of Synechococcus sp.. Without the Synechococcus sp., the tropical/subtropical ocean ecosystems will suffer and experience major trophic cascades. By increasing the thermal tolerance of the Synechococcus sp., we can establish their future. Additionally, by starting early, we do not have to scrabble to revive the community like we are currently experiencing with coral reefs. (2) Population Dynamics: both oceanographers and marine biologists monitor population dynamics to identify changes within the interactions between various organisms. However, if populations within the ecosystem continue to change, the dynamics will continue to shift as well. By establishing phytoplankton — the base of the trophic level and the beginning of every food web — in the future, we can prevent dramatic community shifts. (3) Oceanographic Projections: Studies, like the one produced by Thomas et al. (2012), use satellite data/imagery to make projections of future oceanographic and atmospheric conditions and how it will affect the potential biology of the ocean. Typically, these projections extend from phytoplankton to zooplankton. For example, in the study with Thomas et al. (2012), they project phytoplankton community shifts by examining their thermal tolerance and the projections of future ocean temperatures using satellite data. However, in their study, they stated that their predictions lean more conservatively as they could not account for the rate or potential of phytoplankton evolution. Again, if this study is successful, we can increase the theoretical limit of each phytoplankton species’ thermal tolerance and incorporate the data into these projections.
Works Cited:
- Grossman, A. R., Mackey, K. R. M., and Bailey, S. (2010). A perspective on photosynthesis in the oligotrophic oceans: hypotheses concerning alternate routes of electron flow1. J. Phycol. 46, 629–634. doi: 10.1111/j.1529–8817.2010.00852.x
- Thomas, M. K. et al. (2012). A global pattern of thermal adaptation in marine phytoplankton. Science.