Environmental drivers of spatial variability of Chilean Benthic Marine Invertebrates

Chilean benthic ecosystems make an ideal test case for studying macroecological patterns in species distributions. Chile spans ~39° in latitude, an eco-geographical gradient encompassing five marine ecoregions, significant variation in temperature, salinity, oxygen, solar radiation, and primary productivity, all of which are potential factors driving benthic community structure. This thesis aims to understand how key environmental drivers and human activities influence the spatial variability of benthic marine invertebrates along this gradient. I compile a new integrated biodiversity database and use it to calculate diversity metrics related to species richness, taxonomic diversity and functional diversity, and combine this with data on environmental covariates and human activities. Species richness and functional richness peaked between 42°-46° S. Taxonomic diversity increased south 42° S. Functional evenness peaked toward extreme northern and southern latitudes. Major anthropogenic activities related to diversity were aquaculture and human population density; however, contrary to expectations, diversity increased with increasing levels of these human pressures. My results highlight the importance of the Humboldt Current System for functional diversity: environmental stress (depletion of oxygen at maximum bottom depth and increasing sea bottom nitrate) modulates the benthic communities in this region. Hydrographic variability driven by bottom temperature and salinity gradients in the Patagonian fjords system influences taxonomic and functional diversities of benthic communities. My research confirmed the importance of latitudes between 42°-46° S as an area of high diversity of benthic marine invertebrates. Here, diversity is mainly driven by peaks of primary productivity. I argue that benthic invertebrate assemblages are composed of communities presenting a small volume of functional traits space, formed mainly by species tolerant to the environmental conditions, using available resources such as food and space, and presenting lower competition per resource. These communities show moderate levels of resilience to environmental changes and resistance to species loss.