Data from Persistent kelp forests during a massive decline reveal the importance of land-sea connectivity [Dataset]

The different datasets present data on the benthic community assemblage in remnant habitat patches of bull kelp in 9 sites in Northern California, US, and related environmental variables driving its composition. For the study we used a combination of in situ field surveys (years 2020 to 2022), remote sensing data (years 2016 to 2022), and a laboratory grazing experiment with urchins (Strongylocentrotus purpuratus). We found that, in addition to the two dominant states (kelp forest vs. urchin barren), there is a third community state dominated by understory canopy-forming macroalgae that stays subsurface. Moreover, bull kelp abundance and cover were positively associated with freshwater flow and proximity to freshwater sources, and bull kelp persistence was positively associated with sand cover, all of which seem to diminish sea urchin abundance and negative effects of sea urchin herbivory on bull kelp. This was also shown in the laboratory experiment where sea urchin herbivory rates on bull kelp decreased with decreasing salinity. Overall, these results suggest that freshwater influence in shallow coastal environments could prevent loss of bull kelp and show that land-sea connections should be considered for species-specific management and conservation actions

Funding for this research was provided by the Anthropocene Institute, The Nature Conservancy, California Sea Grant (Grant #R/HCE-15), and the National Science Foundation (DISES Grant #2108002). AMR received the support of a fellowship from ”La Caixa” Foundation (LCF/BQ/PI23/11970014)”

This work contributes to the Institut de Ciències del Mar "Severo Ochoa Centre of Excellence" accreditation CEX2024-001494-S funded by AEI 10.13039/501100011033 of the Spanish Ministry of Science and Innovation

1. kelp_data_Ricart_et_al.csv: species abundances collected in 2 x 30m transects and environmental variables from the different study sites from years 2020, 2021 and 2022. 2. kelp_data_Ricart_et al_metadata.csv: metadata related to the above dataset. 3. urchin_salinity_exp_Ricart_et_al.csv: results from laboratory experiment to assess feeding rates of sea urchins (Strongylocentrotus purpuratus) on bull kelp stipes (Nereocystis luetkeana) for 72h at different seawater salinity. 4. urchin_salinity_exp_Ricart_et_al_metadata.csv: metadata related to the above dataset

Peer reviewed