Small islands in the Gulf of California support extraordinarily high densities of many species compared to larger islands or the mainland. Three variables are important: productivity flowing from the marine to terrestrial ecosystems; the presence of predators; and relative colonizing ability. Small island receive more nutrients from shore drift and marine birds (land plants provide little energy). The scaling effect is counter-intuitive to the general notion that larger islands are more productive. Scaling also influences predation: small islands lack many predators found on larger islands, allowing high marine productivity to produce large populations. Predators drastically reduce population size on larger islands and the mainland. Thus community and food web dynamics vary greatly with habitat size, productivity, species composition and dependence on habitats. Overall, the research objectives are to connect the seemingly unrelated food webs form marine and terrestrial systems and to integrate elements of landscape ecology with the effects of variable production and productivity to understand food web and community structure. In general this research provides an understanding of factors affecting abundance and biodiversity. This system is a general model for fragmented habitats, each of different size and each exhibiting different combinations of species and interconnections to other habitats.
