Coral reefs have tremendous environmental, economic, and cultural value but are in dramatic global decline. Over the last 4 decades, coral cover on Caribbean reefs has declined by ~80% and on Pacific reefs by more than 50%. Declines are being driven by a host of anthropogenic stresses including global change, overfishing, pollution, and disease spread, but all of these stresses generally result in losses of corals, increases in seaweeds, and then a loss of reef resilience as seaweeds dominate and suppress corals.
Ice sheets have gone through periods of rapid melting, causing sea level to rise many times faster than the current rate of rise. Some of these rapid melting events have occurred during periods when ocean and atmospheric temperatures were at or just above modern temperatures. It is thought that there are instabilities intrinsic in the dynamics of ice sheet flow and melting that may cause such rapid sea level rise events, even without changing climate.
Plastic marine debris or the plastisphere impacts marine organisms through ingestion, entanglement, and as a source of toxic chemicals. The plastisphere could also have a major impact on biogeochemical cycles in the oceans. Plastics are transported via major ocean currents to central gyres, where they reside for decadal time scales. The amount of plastic waste is large, exceeding 2 kg/ km2 in central gyres. Even the most recent ocean surveys cannot account for the amount of debris estimated to enter the ocean, with inputs and outputs differing by orders of magnitude.
Advection and biological consumption are both important sinks for oil and gas released from natural seeps in the Gulf of Mexico. We will use a combination of stable isotope measurements and high resolution modeling with both passive and positively buoyant tracers to study the interaction between physical and biological processes in distributing and transporting the carbon released from natural seeps. We will focus on three major seep fields in the Northern Gulf with different water depths –GC185 (ca. 400 m), GC600 (ca. 1200 m), and GC767 (ca.
Many densely populated coastal areas around the world are low lying and susceptible to relative sea level rise (SLR) associated with climate change, land level subsidence or tectonic subsidence. Coastal defense structures have been constructed as barriers to certain design storm surge, storm wave or tsunami heights. Typically even without SLR the design criteria change over time as hazards get reanalyzed or remodeled. The decrease in risk reduction due to relative SLR and the performance of existing defense barriers under loading conditions beyond the design need to be determined.
Geochemical time series from remote Pacific atolls have provided long records of climate variability that extend into the pre-industrial era. Recent studies document a wide range of geochemical variability in corals growing on the same reef, ostensibly of the same genus. Deciphering which fraction of coral geochemistry variations are driven by changes in physical environment versus physiological differences between corals is key to constructing more robust records of past climate variability.
The project aims at further testing a new approach, the maximum entropy production (MEP) model of surface heat fluxes (Wang et al, 2014), for modeling and monitoring air-sea exchange of water and heat air-sea water and heat.
The recently completed resource assessment for ocean current energy (Haas et al. 2013) utilized fairly simplistic analytical methods to estimate the extractable energy from the Gulf Stream System as well as to analyze the relative impacts of large scale energy extraction. This level of analysis can be considered to be accurate to an order of magnitude and only provides an idea on the overall trends of the impacts of extraction. Much higher resolution modeling is required to accurately determine the overall impacts of extraction for both localized and far field effects.
Single-celled marine algae are especially chemically rich, producing toxins that kill fish, marine mammals, and seabirds, contaminate shellfish, and threaten human health. Many predators of these algae – copepods – selectively consume less toxic algae, which in turn sense copepods via an excreted blend of copepod-specific molecules. These algae then become up to 20X more toxic when they sense copepod cues in the open ocean.
