ABSTRACT

The Northern Gulf of Alaska (NGA) is a highly productive subarctic marine ecosystem, and diverse coastal communities have relied upon it for hundreds and thousands of years. Today, the NGA ecosystem continues to support national fisheries, local coastal communities, and Tribal governments in terms of food, culture, and economy. The NGA Long Term Ecological Research (LTER) site aims to understand this dynamic ecosystem. The NGA LTER overarching conceptual framework is that intense environmental variability ? both temporally and spatially ? has yielded a highly resilient ecosystem through species adaptation and community organization. Building off 25 years of multidisciplinary observations along the Seward Line and findings from Phase I of the NGA LTER, Phase II is improving mechanistic understanding of this biome?s key organisms, ecological processes, and responses to climate change. Phase II continues to educate students at all levels and to engage with local communities to understand the questions and concerns that they have regarding this ecosystem. Various agencies and organizations partner with and leverage the NGA LTER, demonstrating the importance of this LTER site and the data collected for the Gulf of Alaska region.

Building on long-term data sets and findings from Phase-I, Northern Gulf of Alaska LTER Phase-II research has three primary goals. First, the investigators are continuing collection and analysis of long-term ecosystem data to understand species abundance and connectivity, as well as their relationships to event-scale and long-term change. Second, the team is exploring functional redundancy of organisms as an underpinning of ecosystem resilience. Despite modest species richness, the NGA hosts numerous instances of ?redundant? taxa with comparable trophic roles throughout the food web; the investigators propose that these taxa, with differing but complimentary nutritional strategies, life histories, and life-cycle timing, contribute to functional redundancy. Redundancy stabilizes variability at higher trophic levels, thereby conferring resilience to the system (i.e., maintenance or recovery of key ecosystem properties in response to disturbance), and the degree to which redundancy stabilizes food webs has not been well explored in pelagic marine ecosystems. Third, the team is investigating the ecological role of physical fronts (i.e., transitions between different water masses) and associated ecotones (i.e., transitions in biological community structure) in the NGA. NGA is making use of new technologies that can overcome historical limitations to the study of fronts and their constituent communities at biologically relevant spatial and temporal scales. The investigators hypothesize that fronts exert a disproportionate influence on key ecosystem properties (e.g., production, export, biological diversity) and are thus related to whole-ecosystem resilience. In addition, fronts are likely to be influenced by both event-scale and long-term environmental change. The observations and experimentation under each of these three themes are coupled to modeling activities to understand relevant physical and biological relationships that occur at frontal transitions. These biome-specific formulations are exploring historical, current, and future ecological states based on climate scenarios predicted for the NGA. Collaboration with other LTER sites is further enhancing understanding of ecological theory.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

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