Bull kelp (Nereocystis luetkeana) growth rates as climate stress indicators for Canada’s Pacific coast

• DOI: 10.1139/facets-2023-0237
• Publication Date: 2024-10-02T11:00:18Z
• Authors: Ondine Pontier; Olivia Rhoades; Brenton Twist; Dan Okamoto; Margot Hessing-Lewis
• Keywords: bull kelp; growth; Science; Q; bioindicator; temperature; nereocystis luetkeana; primary producer; L; Education

Primary producers’ growth rates are ideal bioindicators of changing climate due to their sensitivity environmental conditions. On the Central Coast British Columbia, we assessed Nereocystis luetkeana, a canopy-forming annual kelp, by assessing baseline variability in and response conditions over 600 individuals across three sites (2016–2019). Optimal for blades stipes (∼13–14 cm/day) occurred within narrow range local Growth decreased at temperatures > 10 °C, below 1 µm/L nitrate concentration, surface light availability reduced blade low high levels (daily integral or DLI <20 >40 mol/m2/day). Spatiotemporal these drivers co-occurred with differences rates, suggesting that strongly influenced growth. In particular, temperature nutrients were un-coupled seasonally this region, more variable responses primary growing season (May September). Overall, kelp climatic suggests it is useful bioindicator management marine planning efforts (e.g., restoration aquaculture) its species provides feasible metric monitoring.