9527888 Polis This work examines what factors determine the distribution, abundance, and diversity of key groups along the Gulf of California. Many species of insects, spiders, scorpions, lizards and mammals are extraordinarily dense on small islands and coastal areas compared to larger islands or the mainland. Several factors are important: productivity flowing from the marine to terrestrial ecosystems via shore drift and bird colonies; size of the island (its shoreline to area ratio); variable terrestrial productivity; and the presence/absence of predators. The marine and terrestrial food webs will be connected by examining how marine input penetrates inland and how it affects key species. How primary productivity by land plants changes with variable precipitation (drought to heavy rainfall associated with El Nino events) will be determined, as will differences in soil nutrients caused by seabird fertilization and how the terrestrial system responds to such changes. This research investigates several issues with applied importance. First, it analyzes the potentially great influence that marine input exerts on the dynamics of key populations, food webs, and ecosystems of island and terrestrial coastal communities. This is novel and important, since coastal communities cover about 8% of the earth and contain more than 65% of humans and a disproportionate amount of biodiversity and productivity. Second, this research addresses how El Nino, a major planetary weather maker, influences the productivity and structure of land communities. Third, it illustrates a ubiquitous process: the flow of nutrients, detritus, prey, and consumers across habitat boundaries. Finally, this system is a general model for the ecology of islands and fragmented habitats (e.g., nature reserves), each of different size, and each exhibiting different combinations of species and interconnections to other habitats. It also provides a general understanding of factors affecting abundance and biodiversity.
