Kelp are foundation species that support high levels of biodiversity and, either directly or indirectly provide a wide range of ecological goods and services to human society. In recent decades, due to the high demand for kelp-derived products such as alginate, commercial wild harvesting has increased, leading to declines of kelp biomass in some regions. Chile accounts for 40% of the global kelp harvest, with the subtidal kelp, Lessonia trabeculata being one of the main target species. Currently, however, there is a lack of information on how different degrees of harvesting intensity, governed by distinct management regimes and their enforcement influences L. trabeculata populations. Here we examined the effect different management regimes, characterised by distinct levels of exploitation of kelp and kelp-associated fauna, have on L. trabeculata density and morphology along ~ 1600 km of the Chilean coastline. The findings demonstrated that harvesting intensity likely influences both L. trabeculata density and morphology. Juvenile density of L. trabeculata was five times higher in the most harvesting-affected areas, while kelp morphology values, including holdfast diameter, number of stipes and total length, were always higher in the less-intensively harvested areas. Our study suggests that different degrees of protection can influence density and morphology of subtidal  L. trabeculata populations, which in turn has important implications for the conservation of the kelp forest ecosystems and management of this important fishery.

Resumen.-Las costas de Chile y California central representan importantes puntos de comparación para el estudio de convergencias ecológicas como la composición de parásitos en distintos hospederos. Ambas costas presentan similares condiciones ambientales junto con compartir muchas familias de distintas especies. Se analizó la diversidad parasitaria de especies de peces de ambas zonas comparando si existe similitud entre estas faunas, además se determinó la presencia de 6 grupos taxonómicos de parásitos a través de la literatura y en bases de datos para cada zona (Chile y California). Se creó una matriz de presencia ausencia para las especies de peces estudiadas de ambas zonas y se realizó un análisis de similitud para probar si la composición parasitaria era similar. Los taxones de parásitos mayormente encontrados en peces de California Central correspondieron a digeneos y nemátodos mientras que en Chile central se encontró una mayor diversidad (Digenea, Annelida, Copepoda, Acanthocephala y Nematoda). El análisis de similitud mostró que las comunidades parasitarias entre Chile y California son diferentes significativamente, sin embargo, se obtuvieron sobreposiciones en la diversidad parasitaria agrupándose los hospedadores en 3 grupos, uno de los cuales estuvo conformado por hospedadores de ambas zonas. Esta diferencia puede ser explicada por la reducida diversidad de parásitos en el ensamble de peces del intermareal rocoso en California, tal vez debido a los escasos estudios existentes sobre parásitos de peces intermareales en California, junto con posibles factores no estudiados hasta el momento.Palabras clave: Peces intermareales, parásitos, Chile, California, similitud, diversidad parasitaria, convergencia evolutiva Abstract.-The coasts of central Chile and central California are important points of comparison in the study of ecological convergence such as a host's parasite load because of their similar environmental conditions and the shared presence of many families of different species. In this study, the diversity of parasites in fish species from both zones was analyzed and compared to establish if there are similarities between them. The presence of 6 taxonomic groups of parasites was determined using published literature and databases for each location. A presence-absence matrix was created for the fish species studied in Chile and California, and a similarity analysis was carried out to prove whether the parasite loads of both zones were similar. The parasite taxa most frequently found in fish in central California were Digenea and Nematoda, whereas in central Chile the common taxa were Digenea, Annelida, Copepoda, Acanthocephala, and Nematoda. The similarity analysis showed that the parasite composition was different between zones. Nevertheless, overlaps were obtained in the parasitic diversity grouping the host in 3 host groups, one of which consists of hosts from both zones. This difference can be explained by the low parasitic diversity in the assemble of rocky intertidal fishes in California, po...

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