such as oxygen, to typically highly reduced sediments at depth alters the microbial metabolic processes occurring around burrows. As bioturbators burrow, they also increase the surface area of sediments across which oxidized and reduced solutes can be exchanged, thereby increasing the overall sediment metabolism. This increase in sediment metabolism and microbial activity further results in enhanced organic matter decomposition and sediment oxygen uptake. In addition to the effects of burrowing activity on microbial communities, studies suggest that bioturbator fecal matter provides a highly nutritious food source for microbes and other macrofauna, thus enhancing benthic microbial activity. This increased microbial activity by bioturbators can contribute to increased nutrient release to the overlying water column. Nutrients released from enhanced microbial decomposition of organic matter, notably limiting nutrients, such as ammonium, can have bottom-up effects on ecosystems and result in increased growth of phytoplankton and bacterioplankton. Burrows offer protection from predation and harsh environmental conditions. For example, termites (Macrotermes bellicosus) burrow and create mounds that have a complex system of air ducts and evaporation devices that create a suitable microclimate in an unfavorable physical environment. Many species are attracted to bioturbator burrows because of their protective capabilities. The shared use of burrows has enabled the evolution of symbiotic relationships between bioturbators and the many species that utilize their burrows. For example, gobies, scale-worms, and crabs live in the burrows made by innkeeper worms. Social interactions provide evidence of co-evolution between hosts and their burrow symbionts. This is exemplified by shrimp-goby associations. Shrimp burrows provide shelter for gobies and gobies serve as a scout at the mouth of the burrow, signaling the presence of potential danger. In contrast, the blind goby Typhlogobius californiensis lives within the deep portion of Callianassa shrimp burrows where there is not much light. The blind goby is an example of a species that is an obligate commensalist, meaning their existence depends on the host bioturbator and its burrow. Although newly hatched blind gobies have fully developed eyes, their eyes become withdrawn and covered by skin as they develop. They show evidence of commensal morphological evolution because it is hypothesized that the lack of light in the burrows where the blind gobies reside is responsible for the evolutionary loss of functional eyes. Bioturbators can also inhibit the presence of other benthic organisms by smothering, exposing other organisms to predators, or resource competition. While thalassinidean shrimps can provide shelter for some