Examining the Role of Marine Mammals and Seabirds in Southeast Alaska’s Marine Ecosystem Dynamics

Melissa Rhodes-Reese,Curry Cunningham,Heidi C Pearson,Cheryl Reese,Janet Moriles-Miller,Joe Roman,David Clay,Joseph D Warren

doi:10.3389/fmars.2021.720277

Abstract

Primary producers are the foundation of marine food webs and require reliable nutrient sources to maintain their important role with ecosystems. While marine mammals and seabirds can play critical roles in marine nutrient cycling, their contributions are often overlooked. Southeast Alaska’s marine environment supports abundant marine mammal and seabird populations in addition to valuable fisheries. Nonetheless, there is still relatively little known about nutrient sources and fluxes in this region which is a critical component of fisheries management. The goal of our study was to advance knowledge of the role of mammals and seabirds in marine nutrient cycling and to understand how changing marine mammal and seabird populations may alter ecosystem dynamics. We utilized qualitative network models (QNMs) to examine how a simulated Southeast Alaska ecosystem would respond to an increase in marine mammals, seabirds, and nutrients. Researchers are increasingly utilizing QNMs as a first step in the development of ecosystem-based fisheries management plans as their adaptable nature is well suited to address rapidly changing climatic conditions. Our results indicate that marine mammals and seabirds make important contributions to marine nutrient concentrations in the region and that these valuable ecosystem services should not be overlooked.

Highlights

Large mammals and birds have a profound impact on nutrient cycling in terrestrial systems (e.g., McNaughton et al, 1997)
As a first step in addressing this information gap, we developed a qualitative network model (QNM) to examine how a simulated Southeast Alaska system would respond to multiple marine mammal and seabird perturbation scenarios
Utilizing QNMs, we model the contributions of marine mammals and seabirds to the ecosystem and discuss how our results may be used to inform EFBM

Summary

Introduction

Large mammals and birds have a profound impact on nutrient cycling in terrestrial systems (e.g., McNaughton et al, 1997). A suite of studies (Nicol et al, 2010; Lavery et al, 2014; Ratnarajah et al, 2014, 2016; Roman et al, 2014) has demonstrated the potential for baleen whale defecation to aid in recycling of autochthonous nutrients and stimulation of primary productivity Despite this mounting evidence ascribing the importance of marine mammals to marine productivity, questions remain regarding the generalizability of these findings as all but two (Roman and McCarthy, 2010; Roman et al, 2016) of the aforementioned studies occurred in the pelagic waters of the Southern Ocean

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Discussion

Conclusion