Initial assessment of coastal benthic communities in the Marine Parks at Robinson Crusoe Island

Abstract

ABSTRACT. The National Biodiversity Strategy developed in Chile aims to protect 10% of the surface area of the most relevant marine ecosystems. The waters around the Juan Fernández Archipelago were not protected until 2014, when a Multiple Use Marine Protected Area was created in the 12 nautical miles around the archipelago, which includes five marine parks in sites of high conservation value. Three of these parks are located around Robinson Crusoe Island. This study aims to define a baseline for monitoring the impact of the marine protected area and provides ecological information to improve the understanding of coastal marine ecosystems around Robinson Crusoe Island. In addition to a characterization of bathymetry and habitats, intertidal and subtidal communities were sampled using transects and quadrats within the marine parks. We quantified species richness and abundances, which were later organized into functional groups for algae and trophic groups for mobile organisms. Although species richness did not vary between sites nor among the habitats sampled, we observed important differences in species abundance and composition as well as in functional and trophic groups both between sites and habitats. Among our results, we highlight: a) the dominance of endemic algae in intertidal and subtidal (mainly corticated and corticated foliose) habitats, b) high abundances of macroinvertebrate herbivores in intertidal habitats and detrivores in subtidal habitats, c) dominance of invertivorous fish in the subtidal, which are the primary predators of mobile benthic organisms. This characterization includes both the inter and subtidal coastal communities of the Juan Fernández Archipelago.

Overview of recent advances in oceanographic, ecological and fisheries research on oceanic islands in the southeastern Pacific Ocean

“…analyzes the updated list of species reported for Easter and Salas y Gómez islands and shows high levels of endemism for the majority of the taxonomic groups, with mollusks and poriferans exhibiting the highest levels overall (33%-34%). Fewer species are shared between Easter and Salas y Gómez islands and continental Chile than between these islands and Juan Fernández Archipelago, or between the archipelago and continental Chile Rodríguez-Ruiz et al, 2014). These findings, based on the limited information available, 668 suggest the need to increase research efforts and science-based conservation plans to preserve the unique species in oceanic island ecosystems.…”

“…In fact, the first marine protected areas around these islands were created in the last two years, 10 years behind those established in continental Chile. This occurred in spite of the high concentration of endemic species Pérez-Matus et al, 2014;Rodríguez-Ruiz et al, 2014) and growing fishing pressure around Chile's oceanic islands Zylich et al, 2014). Nonetheless, a few sporadic studies, associated with both national (e.g., CIMAR, Yáñez et al, 2008) and international initiatives (e.g., Friedlander et al, 2013), have contributed to our knowledge of the ecosystems associated with seamounts and oceanic islands in Chile.…”

“…Recent studies in Easter, Salas y Gómez, and Robinson Crusoe islands have focused on community structure. Additionally to the comparative work by Friedlander et al (2013), Pérez-Matus et al (2014), Wieters et al (2014) and Rodríguez-Ruiz et al (2014) report the most recent studies conducted in the inter and subtidal in the representative habitats of Juan Fernández Archipelago and Easter Island that characterize community structure. Pérez-Matus et al (2014) characterized the coastal ichthyofauna of Robinson Crusoe Island, presenting the first analysis of reef fish and macrobenthic community structure in Juan Fernández Archipelago.…”

“…Pérez-Matus et al (2014) characterized the coastal ichthyofauna of Robinson Crusoe Island, presenting the first analysis of reef fish and macrobenthic community structure in Juan Fernández Archipelago. Rodríguez-Ruiz et al (2014) also conducted recent research in Juan Fernández Archipelago, characterizing coastal communities, from the intertidal to the subtidal zone, studying the three recently created Marine Parks: Tierras Blancas, El Arenal and El Palillo. Among the most relevant patterns in coastal communities at Robinson Crusoe Island, we highlight: a) the dominance of foliose brown and red macroalgae at protected sites, while sessile species (i.e., cnidarians, vermetids, barnacles) structure the substratum at exposed sites , b) high algal species richness and abundance, both in the intertidal and subtidal zones, and particularly high abundance of filamentous algae at sites exhibiting high disturbance (extensive sand dynamics), in comparison with corticated algae and a greater diversity of functional groups at low disturbance sites, c) herbivorous invertebrates, particularly gastropods, dominate the intertidal, while the subtidal is dominated by detritivores, especially at sites were fur seal colonies were present, d) the highest fish abundance was recorded in subtidal habitats of the site were fur seal colonies were not present (El Palillo), and e) carnivorous fish, consumers of benthic invertebrates, dominated Robinson Crusoe's coastal habitats, where a negative relationship between fish abundance and benthic invertebrate abundance was found .…”

“…The characterization of the inter-and subtidal coastal habitats of Robinson Crusoe Island also allowed the advance of hypotheses about processes affecting community structure Rodríguez-Ruiz et al, 2014). Pérez-Matus et al (2014) suggest that habitat-structuring species (e.g., brown algae) explain fish species composition, since differrences in the composition of substratum species and architectural complexity, rather than changes in abiotic factors such as depth, drive species composition and abundance.…”