Point Lobos is a State Natural Reserve of ecological and cultural significance along the Central Coast of California. The Southern Sea Otter (Enhydra lutris nereis), one of the staple species within the Reserve, is listed as a ‘threatened’ species under the Federal Endangered Species Act and a ‘depleted’ species under the Marine Mammal Protection Action (Otter Project n.d.). Population numbers have increased since their discovery off of the Big Sur coast in 1938 but continue to struggle (ibid). There exist an estimated 2,700 otters in the wider Point Lobos region (California State Parks 2018: 4-47).
The continuation of Southern Sea Otters is threatened by the impacts of climate change. In particular, the impacts associated with increasing coastal ocean temperatures. The region has experienced sea surface temperature increases at a rate of 0.2°F per decade from 1920-2014 (OEHHA 2019).
Southern Sea Otters have strong ecological links to the Giant Kelp Forest (Macrocystis pyrifera) – a widely acknowledged special plant community in the Point Lobos Marine Zone (AECOM 2013: 3-53). Southern Sea Otters are a keystone species for the Giant Kelp Forests and contribute to its continuation by controlling the population of grazers, in particular, Purple Sea Urchins (Strongylocentrotus purpuratus) that feed on the Kelp. In turn, Southern Sea Otters seek shelter from storms and predators in the Giant Kelp Forest (AECOM 2013: 3-54).
Rising coastal ocean temperatures is having adverse impacts on the growth rates of the Giant Kelp Forest (NOAA n.d.; Bland 2017). Consequently, the Forests have experienced degradation and decline in recent years along the Central Coast of California (NOAA n.d.; Bland 2017). Thus, due to the interconnected and reciprocal nature of this ecological relationship, enhanced Kelp Forest exposure to the impacts of climate change will result in the enhanced vulnerability of Southern Sea Otters.
Further, warming coastal ocean temperatures is resulting in the rise of Great White Sharks (Carcharodon carcharias) to the region (Blohowiak 2020: 5). Great White Shark bites, once responsible for only 5% of Sea Otter deaths, now account for 50% of deaths (ibid). Most Shark bites are occurring in regions where Kelp canopy cover has declined (Copenhaver 2018). Therefore, increasing coastal ocean temperatures is not only increasing the Shark population in the region – the primary cause of Sea Otter deaths – it is also decreasing Kelp canopy cover – the primary source of shelter for Sea Otters. When compounded, these climate impacts render Southern Sea Otters greatly exposed to climate change.
Finally, ‘Harmful Algae Blooms’ will increase under climate change (Langridge 2018: 67; OEHHA 2019). These blooms are having adverse health impacts on the neurological systems of Sea Otters exposed to the toxins released from the algae (Lee 2021; Langridge 2018: 67).
Keystone Species: A species that exerts greater influence in the ecosystem than its biomass would suggest.
Harmful Algae Blooms: The rapid increase or accumulation in the population of algae in freshwater or marine water systems.
References
AECOM, 2013. Existing Conditions and Resources Inventory Report: Point Lobos State Natural Reserve.
Bland, A. 2017. As Oceans Warm, the World’s Kelp Forests Begin to Disappear. [online] Yale Environment 360. Available at: https://e360.yale.edu/features/as-oceans-warm-the-worlds-giant-kelp-forests-begin-to-disappear [Accessed 10 March 2021].
Blohowiak, D., 2020. Sea Otters: Fascinating, individualistic and still much threatened. Point Lobos Magazine, [online] (Spring 2020), pp.3-6. Available at: https://www.pointlobos.org/sites/default/files/uploads/magazine/Point-Lobos-Magazine-Spring2020.pdf[Accessed 10 March 2021].
California State Parks, 2018. Preliminary General Plan and Draft Environmental Impact Report. Carmel Area State Parks.
Copenhaver, A., 2018. Sea otters’ perilous path to recovery. [online] Monterey Bay Aquarium. Available at: https://www.montereybayaquarium.org/stories/sea-otters-perilous-path-to-recovery [Accessed 18 March 2021].
Langridge, R., 2018. Central Coast Region Report. California’s Fourth Climate Change Assessment.
Lee, K., 2021. Informational Interview on Point Lobos SNR.
NOAA, n.d. Impacts on Kelp Forests | Office of National Marine Sanctuaries. [online] Available at: https://sanctuaries.noaa.gov/visit/ecosystems/kelpimpacts.html [Accessed 15 March 2021].
OEHHA, 2019. Coastal Ocean Temperature: Ocean waters along the California coast are warming. [online] Available at: https://oehha.ca.gov/epic/impacts-physical-systems/coastal-ocean-temperature [Accessed 19 March 2021].
Otter Project, n.d. About Sea Otters. [online] Available at: http://www.otterproject.org/about-sea-otters/[Accessed 11 March 2021].