Impacts of Ocean Change on the Galapagos Marine Ecosystem

THE CHALLENGE

KEY QUESTIONS

• How do distinct physical and chemical environments influence the Galapagos marine plankton and, in turn, how do these communities support higher trophic levels and influence marine carbon cycling?
• What are the effects of dramatic variations in ocean conditions due to El Niño and climate change on the Galapagos marine ecosystem and how does this inform us about changes occurring in other parts of the plant?

People: Adrian Marchetti, Harvey Seim, and Scott Gifford

The Galapagos Marine Reserve (GMR) is comprised of a highly dynamic ecosystem that is vital to the maintenance of biodiversity and food security of the islands. In 2014, a collaboration between the Galapagos Science Center and the Galapagos National Park was established to implement a long-term monitoring program in the GMR. Annual research cruises are conducted during the cool season to survey the waters in and around the Archipelago on board GNP vessels. Two motivations for the cruises are the need for coordinated observations in both space and time to support ecosystem modeling, and to gain an understanding of how episodic climatic events (such as El Niño) impact the GMR. A particular focus has been on understanding how specific physical ocean processes impacted by El Niño influence primary productivity and the resulting microbial (i.e., phytoplankton and bacteria) communities as determined through molecular sequencing. On these cruises, measurements and samples are collected to characterize a broad range of ocean properties across trophic levels. These include physical properties (i.e., temperature, salinity, chlorophyll fluorescence and light profiles at stations across the archipelago and continuous surface measurements along the cruise track), chemical properties (dissolved inorganic nutrients and particulate nutrients) and biological properties (primary productivity, phytoplankton biomass, nitrate uptake rates, bacterial respiration and microbial community composition). Multi-year ocean temperature time series collected at 10-30 m depths from a number of islands that capture tidal to interannual variability. As the marine ecosystem is highly sensitive to ocean changes on both relatively short-term (e.g., storms) and long-term (e.g., El Niño) timescales, continued oceanographic monitoring in the GMR is essential to making well-informed conservation and management decisions in the face of climate change.