Recruitment as a possible indicator of declining resilience in degraded kelp forests

9 pages, 4 figures, 2 table.-- Under a Creative Commons license

Kelp forests are critical marine ecosystems that provide habitat and ecological services, as well as economic benefits. However, kelp forests worldwide are facing multiple pressures, including climate change and human activities. In this study, we investigated whether recruitment success, an infrequently recorded variable in kelp monitoring studies, was affected in degraded kelp reefs where adult golden kelps (Laminaria ochroleuca) were persistently absent due to fish consumption. We conducted a three-year seasonal monitoring of kelp recruits and juveniles in both healthy and degraded kelp reefs in northwest Spain. Our findings reveal a decline in spring kelp recruitment over time on degraded reefs, while it remained stable on healthy reefs. The results indicate that continued herbivory pressure can decrease kelp recruitment, suggesting the potential exhaustion of kelp stand resilience. Altogether, our study highlights the importance of biotic interactions, such as herbivory, in understanding changes in kelp forest dynamics. Moreover, it emphasizes the significance of including recruitment in kelp forest assessments as an indicator of resilience

This research was funded by the “Fundación Biodiversidad y el Ministerio de Transición Ecológica y el Reto Demográfico”. BioCost Research group acknowledges funding from grants ED431B 2021/32 (“Axudas para a consolidación e estructuración de unidades de investigación competitivas do SUG” program, Xunta de Galicia), TED2021-129429B-I00 (co-funded by MCIN/AEI/10.13039/501100011033 and the European Union NextGenerationEU/PRTR) and grant PID2022-142945OB-I00 (funded by MCIN/AEI/10.13039/501100011033/FEDER, UE). SB received financial support from the Xunta de Galicia and the European Union (European Social Found – ESF) (grant ED481A-2018/101). CPC received financial support from Xunta de Galicia “Axudas de apoio á etapa de formación posdoutoral” (grant ED481B-2021/095)

Peer reviewed