Diversity, dynamics and biogeography of Chilean benthic nearshore ecosystems: an overview and guidelines for conservation

Despite Chile has been one of the pioneering countries in studies of human impact on marine communities, and despite the enormous economic and social significance that the marine environment has for the country, the developme nt of marine conservation programs and the scientific basis for sustainabil ity has not kept pace, with the exploitation rate of marine fisheries and t he increasing use of the coast for other purposes. Although we think that t he establishment of any conservation policies along the vast coastline of C hile must be based on a multitude of approaches and considerations, scienti fic, biological, and ecological principles should guide much of these effor ts. In this paper, we attempt to present a general overview of the current knowledge about the ecology and biogeography of nearshore systems in Chile. Based on the most relevant existing information, our goals are to: 1) Iden tify major biogeographic and ecological features of nearshore ecosystems, a nd the obvious gaps in information, 2) identify the most harmful human acti vities impacting the structure and dynamics of these systems, and 3) sugges t the possible use of indicators to assess the conservational status of dif ferent environments along the coast. This overview shows, on one side, the geographic areas of deficitary knowledge on nearshore environments that are critical for future marine conservation and management plans, and on the o ther, the availability of high quality information for other geographic are as along the coast. Regarding the taxonomy and large-scale patterns of spec ies distribution, important gaps in information were detected, however no b ig changes in the total number of species are expected in the future. There are few large-scale patterns of species distribution are reported in the l iterature, and in this contribution, but more work needs to be done, partic ularly for some taxa, to identify areas of high species diversity as well a s areas which possess unique characteristics in terms of ecosystem processe s (e.g., particular disturbance and upwelling regimes in coastal marine eco systems) and species (e.g., endemic and keystone species). For most marine invertebrates and macroalgae, hotspots in species diversity are present in southern Chile. New studies addressing the causal factors generating these large-scale patterns of species distribution are also needed; information a bout coastal oceanography and larval supply is still poor. This information crucial for the design of a marine reserve network. The information availa ble on community structure and ecosystem functioning, especially highlighti ng the effect of human impact, comes from very few geographic regions. More information about community structure for other areas of the coast is requ ired, particularly considering the strong differences in temperature, circu lation patterns, habitat heterogeneity, species composition, as well as of upwelling and El Nino effects along the 4,000 km of coastline. Finally, we list what we think are the most harmful human activities by area and enviro nment along the coast, and integrate this information to suggest possible e nvironmental indicators, and basic needs and guidelines for marine conserva tion in Chile.