Oceanographic Monitoring in Cook Inlet and Kachemak Bay, CTD Data, 2012-202, Gulf Watch Alaska Environmental Drivers Component

The lower Cook Inlet/Kachemak Bay oceanographic monitoring project collected oceanographic and plankton data year-round at high temporal frequency and spatial resolution from 2012 to present to assess the effects of oceanographic variability on nearshore and pelagic species injured by the 1989 Exxon Valdez oil spill. The project is part of Gulf Watch Alaska (GWA), the long-term ecosystem monitoring program of the Exxon Valdez Oil Spill Trustee Council (EVOSTC), within the Environmental Drivers component of the program. Shipboard oceanographic and plankton surveys were made along repeated transects from February 2012 to August 2022, with monthly sampling along a mid-Kachemak Bay transect, and quarterly seasonal sampling along an outer Kachemak Bay and three lower Cook Inlet transects. Oceanographic data were collected at vertical stations with conductivity-temperature vs depth (CTD) profilers (SeaBird Electronics 19plus), with vertical measurements of dissolved oxygen, turbidity, fluorescence, and light availability also made from attached sensors. CTD data were processed using SBE Data Processing software. The final dataset is composed of post-processed text (CSV format) files, with one file provided for each study year. The files contain processed CTD data in 1 meter vertical bins, which have been aggregated from sampling conducted at all times and transects for each year. Coincident with the oceanographic observations, zooplankton and phytoplankton net tows were conducted at three of the stations along each transect to identify spatial and seasonal patterns in plankton biomass and community composition, and to assess plankton community response to environmental changes. Opportunistic seabird and marine mammal observations were conducted during shipboard surveys, in collaboration with the U.S. Fish and Wildlife Service Migratory Bird Program. Both the plankton and seabird studies are available as seperate datasets referenced under Related Resources.