Relation of Caulerpa racemosa (Forsskål) J.Agardh, 1873 (Chlorophyta;Bryopsidales) with the benthic sessile organism diversity and potential use of Sacoglossan molluscs as biocontrol agents in Santa Cruz, Galapagos Islands

The macroalga Caulerpa racemosa (Forsskål) J. Agardh, 1873 is a cryptogenic species within the Galapagos Marine Reserve (GMR) that possesses a high potential for invasion. The presence of this species leads to sediment accumulation, which can have detrimental effects on native species by hindering their growth and even suffocating them. In this study, we compared Shannon-Weiner diversity, Simpson dominance, and Pielou's evenness index across three study sites around Santa Cruz Island, Galapagos. We observed that C. racemosa dominated two of the three bays, resulting in reduced diversity and evenness of benthic sessile species in those areas. Additionally, we focused on the collection of three sacoglossan molluscs, namely Berthelinia chloris (Dall, 1918), Lobiger sagamiensis Baba, 1952, and Oxynoe sp., from Tortuga Bay. These molluscs were examined as potential biological control agents for the alga. Their grazing rates were determined to be as follows: B. chloris = 0.15 g·d-1, L. sagamiensis = 0.21 g·d-1, and Oxynoe sp. = 0.47 g·d-1. Furthermore, it was found that water temperature significantly influenced their grazing rates. Among the three species, Oxynoe sp. exhibited the highest egg-laying capacity per week, with 54,320 eggs, followed by B. chloris with 46,856 eggs and L. sagamiensis with 21,763 eggs.