Seafloor primary production in a changing Arctic Ocean

Area of Science:

• Marine ecology
• Arctic Oceanography
• Carbon cycling

Background:

• Phytoplankton and sea ice algae are traditionally viewed as the primary producers in the Arctic.
• Benthic primary producers (BPPs), including microalgae, macroalgae, and seagrasses, are a poorly quantified but potentially significant source of marine primary production.
• Models suggest BPPs cover approximately 3 million km² of Arctic coastal and shelf seas.

Purpose of the Study:

• To explore the importance of BPPs in the Arctic marine ecosystem.
• To quantify the contribution of BPPs to Arctic primary production.
• To assess the impact of climate change on BPPs and their habitats.

Main Methods:

• Synthesis of published data on BPPs in the Arctic.
• Application of a novel model to estimate BPPs' contribution to primary production.
• Analysis of changes in Arctic seafloor area exposed to sunlight and its correlation with BPP distribution and productivity.

Main Results:

• BPPs contribute an estimated 77 Tg C y⁻¹ to Arctic primary production, representing 20-35% of phytoplankton production.
• Macroalgae contribute ~43 Tg C y⁻¹, seagrasses ~23 Tg C y⁻¹, and microalgae ~11-16 Tg C y⁻¹.
• The sunlit seafloor area has increased by ~47,000 km² y⁻¹ since 2003, expanding BPP habitats, with expected increases in macrophyte productivity due to warming and ice loss.

Conclusions:

• BPPs are a major contributor to Arctic marine primary production, necessitating their inclusion in ecosystem models and carbon budgets.
• Climate change impacts BPPs complexly; while warming and ice loss favor macroalgae, reduced water transparency may limit microalgal production.
• Further research is crucial to address knowledge gaps regarding Arctic BPPs' distribution, productivity, and role in the ecosystem.