The Pacific Marine Heatwave: Monitoring During a Major Perturbation in the Gulf of Alaska. Long-Term Monitoring Program (Gulf Watch Alaska) Synthesis Report, (Exxon Valdez Oil Spill Trustee Council Program 19120114)

Suryan RM, Lindeberg MR, Aderhold DR (ed). 2021. The Pacific Marine Heatwave: Monitoring During a Major Perturbation in the Gulf of Alaska. Long-Term Monitoring Program (Gulf Watch Alaska) Synthesis Report, (Exxon Valdez Oil Spill Trustee Council Program 19120114). Exxon Valdez Oil Spill Trustee Council. Anchorage, Alaska

Gulf Watch Alaska is an interdisciplinary marine ecosystem monitoring program designed to inform restoration needs and activities for Exxon Valdez oil spill injured resources within the context of long-term environmental variability. One of the most significant, contemporary environmental events in the Gulf of Alaska (GOA) was the 2014-2016 northeast Pacific marine heatwave (PMH), which occurred soon after Gulf Watch Alaska began. This science synthesis report highlights major findings from Gulf Watch Alaska during the first 8 years of long-term ecosystem monitoring and the ecosystem-level impacts of the PMH. The report is structured around four manuscripts produced with the Herring Research and Monitoring Program and other collaborators. These manuscripts collectively use over 200 physical and biological time series to describe the development of the PMH and biological responses. Analyses of ocean temperature data showed that correlation length scales generally degraded considerably beyond 100 km, but that the PMH heatwave signal was so strong that surface waters (0-50 m) from the intertidal zone to the outer continental shelf warmed contemporaneously with offshore waters. Heating mechanisms and timing, however, differed for surface and near-bottom waters. The highly anomalous warming of the PMH affected rocky intertidal habitats across the northern GOA such that community structure that formerly appeared to vary independently within each region, showed remarkably similar responses across regions during and after the PMH. Likewise, in the pelagic prey and predator food web, the PMH coincided with the collapse of multiple forage fish populations, which disrupted energy flow to higher vertebrate predators and caused major reductions in abundance and productivity. Not all responses however were negative but were nonetheless together sufficiently strong to produce a GOA ecosystem community structure post-PMH that was different then years prior. Looking forward, we propose to build upon these data synthesis efforts while we continue to improve and expand the products that we provide to stakeholders. Developing a more complete understanding of the ecosystem effects of climate variability and other perturbations is critical to reducing uncertainty that can hinder marine resource recovery designations and economic development in the GOA.

Type
Published Report
Date of Issue
2021-03-11
Publisher
Exxon Valdez Oil Spill Trustee Council
Units
KATM , KEFJ , SWAN
Keywords
Environmental Drivers, Exxon Valdez Oil Spill Trustee Council, Gulf of Alaska, Nearshore Ecosystem, Pacific marine heatwave, Pelagic Ecosystem, PMH
Subjects
Ecological Framework: Air and Climate | Weather and Climate | Weather and Climate , Ecological Framework: Geology and Soils | Geomorphology | Coastal/Oceanographic Features and Processes , Ecological Framework: Geology and Soils | Geomorphology | Marine Features and Processes , Ecological Framework: Water | Hydrology | Marine Hydrology , Ecological Framework: Biological Integrity | Focal Species or Communities | Marine Communities , Ecological Framework: Biological Integrity | Focal Species or Communities | Intertidal Communities , Ecological Framework: Biological Integrity | Focal Species or Communities | Marine Invertebrates

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