Non-trophic interactions amplify kelp harvest-induced biomass oscillations and biomass changes in a kelp forest ecological network model

• Main Authors: Perala, Tommi, Pesari, Susanna
• Format: Other/Unknown Material
• Language: unknown
• Published: Zenodo 2023
• Subjects: kelp harvesting; Northeast Atlantic; food web; habitat complexity; Atlantic cod; European lobster; allometric trophic network model; Laminaria; atlantic cod; Gadus morhua; Homarus gammarus
• Online Access: https://doi.org/10.5281/zenodo.7763090

Kelp forests are important marine ecosystems providing habitat for numerous species. Despite over 50 years of mechanical harvesting in the Northeast Atlantic, the indirect impacts of kelp harvesting and associated habitat loss on faunal species within kelp forests remain poorly understood. We investigated the consequences of kelp harvesting by developing an allometric trophic network model for a subtidal Northeast Atlantic kelp forest (dominated by Laminaria hyperborea ). Additionally, we designed a novel mechanistic model to explore the non-trophic interactions between kelp and age class 0 Atlantic cod ( Gadus morhua ) and kelp and European lobster ( Homarus gammarus ), specifically focusing on the increased survival benefits provided by the kelp habitat. Simulations were conducted over a 50-year period, incorporating harvesting cycles of 2, 5, and 9 years, as well as low and high harvesting intensities. Our findings reveal the complex dynamics resulting from kelp harvesting. The recovery of kelp biomass was observed with 5- and 9-year harvesting cycles, whereas a decline was observed with a 2-year cycle. Furthermore, the non-trophic interaction facilitated a higher pre-harvest biomass for both the European lobster and the Atlantic cod compared to scenarios without this interaction. These results highlight the multitrophic effects of kelp harvesting and emphasize that the recovery of kelp-associated species may not necessarily align with kelp recovery, depending on harvesting intensity and recovery periods. Importantly, our study contributes to a better understanding of the ecological consequences of kelp harvesting and underscores the need for sustainable management practices to mitigate habitat loss in kelp ecosystems. Funding provided by: Academy of Finland Crossref Funder Registry ID: https://ror.org/05k73zm37 Award Number: 317495 Funding provided by: Academy of Finland Crossref Funder Registry ID: https://ror.org/05k73zm37 Award Number: 350392 Funding provided by: European Research Council Crossref ...