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

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.

Whales in the carbon cycle: can recovery remove carbon dioxide?

“…Whale excreta released in surface waters are rich in limiting nutrients. These nutrients, released across both vertical and horizontal gradients, may stimulate carbon fixation by phytoplankton, enhancing ecosystem productivity and potentially stimulating carbon storage, export, and sequestration (Figure 1) [11,40,54,55]. Two indirect pathways are discussed next: the whale pump and the great whale conveyor belt.…”

Whales and climate

“…Case studies are lacking from most regions, which is particularly r e l e v a n t g i v e n t h e n o r t h e r n / s o u t h e r n h e m i s p h e r e dichotomy in micronutrient limitation (Wing et al, 2014). This includes the lack of emerging research on the carbon cycle of all marine vertebrates such as fish and seabirds Rhodes-Reese et al, 2021) and the nutrient uptake by bacteria and viruses (Ratnarajah et al, 2018). Viruses are widely distributed in the marine environment, accumulating carbon at an equivalent to over 75 million blue whales (Suttle, 2005).…”

A risk assessment for the remote ocean: the case of the South East Atlantic

“…Other pressures from fishing in ABNJ relate to bycatch of nontarget species including seabirds, top predators and fishes. The removal of non-target species threatens associated direct benefits such as food and nutrition, spiritual wellbeing (Tilot et al, 2021) and opportunities for tourism and indirect benefits such as a healthy climate (Davison et al, 2013;Rhodes-Reese et al, 2021). As the complexity of ecosystems is reduced, through the removal of top predators, this corresponds with a reduced resilience of an ecosystem to adapt to other pressures such as changing ocean chemistry and temperature which exacerbates the risk of ecosystem service loss (Pauly et al, 1998;Myers and Worm, 2003;Davison et al, 2013;Daw et al, 2015;Cheung et al, 2018).…”