An understanding of environmental responses to current and emerging problems and the capacity to forecast future threats requires appropriate indicators. The temporal scale of impact to animal health and species biodiversity can vary from centuries in the case climate change, to immediate, such as chemical spills. This dissertation uses genetics, physiology, and community ecology to understand current and emerging environmental threats and appropriate biomonitoring responses across a range of temporal scales.
Patterns of genetic diversity across a species range can suggest past glacial refugia and recolonization, dispersal barriers, and evidence of vulnerabilities to future change. However, population genetic structure and historical refugia among co-occurring species is not well characterized for many groups of aquatic organisms. Therefore, I compared phylogeographies of five, large bodied co-occurring aquatic insect species (four stoneflies: Calineuria californica, Hesperoperla pacifica, Pteronarcys californica, and Pteronarcys princeps and one caddisfly: Dicosmoecus gilvipes) across their ranges.
Widespread and persistent environmental contaminants may be monitored in the marine environment using top predators such as marine mammals. I sampled serum, inner blubber, and outer blubber and determined predictive equations between tissues for a suite of persistent organic pollutants in northern elephant seals (Mirounga angustirostris), which indicated strong relationships, particularly between serum and inner blubber POP concentrations.
Although benthic macroinvertebrate communities respond to natural environmental fluctuations they can still serve as indicators of acute anthropogenic stressors. Multiple years of macroinvertebrate sampling (2004, 2010-2013) in an urban creek quantified the community response to an accidental, 3000 L, oil spill using a Before-After Control-Impact approach. Taxa richness and sensitive taxa decreased immediately, but recovered one year later, likely aided by drift from upstream reference sites and winter rains. Additionally, I identified five indicator taxa that will enhance future biomonitoring efforts.
To better understand population dynamics and response to drought in seasonal wetlands, I investigated successional changes in macroinvertebrate occurrence and abundance in northern California. The early-season predator assemblage was dominated by dytiscid beetles and late-season by Lestes damselflies. The phenology of taxa and life history strategies may affect how macroinvertebrate populations respond to increased annual variation in hydroperiod as a result of future climate change.