Lanterna Rally

Author: Alison Mae McNally

Publisher:

Published: 2014

Total Pages:

ISBN-13: 9781321363357

Invertebrates are among the most imperiled species on Earth, with an estimated one in five facing extinction in the near future. Habitat loss, invasive species and pollution all contribute to the loss of invertebrate biodiversity, especially those that persist in fragmented ecosystems. The Lange's Metalmark butterfly (Apodemia mormo langei), a subspecies of the more widespread Mormon Metalmark (Apodemia mormo), is such an example, having been listed as endangered under the Federal Endangered Species Act in 1976, and endemic to a small stretch of relict dunes along the San Joaquin River near the town of Antioch, California, in what is now the Antioch Dunes National Wildlife Refuge (NWR). Industrial and urban pressures have degraded the sand dune habitat of the Lange's Metalmark from mobile sandy areas supporting stands of their host plant, the Antioch Dunes buckwheat (Eriogonum nudum var. psychicola) to a stabilized dune system overrun by invasive grasses and forbs. Peak flight numbers of the insect have been on the decline since 1999, hitting a critical low of 45 in 2006, and a mere 28 in 2013. By examining the historical geography of the Antioch Dunes NWR, the seasonal averages of precipitation and temperature, and atmospheric aerosols deposited on site, this research aims to better understand abiotic factors contributing to habitat decline at the Antioch Dunes NWR, and, ultimately, to population decline of the Lange's Metalmark butterfly. Ultimately, the objective is that this research adds to a larger body of work whose goal is to restore habitat for and increase the population of the butterfly. Chapter One looks at the historical ecology of the Antioch Dunes, and investigates the origin and age of the dune system, which allows for a better understanding of how long the Lange's Metalmark and its ecosystem have existed at the Antioch Dunes. Anthropogenic uses and disturbances are also tracked through time and their role in population decline of the insect and degradation of its habitat discussed. In Chapter Two, multiple regression models were used to look at the influence of seasonal climatic variability on the population of the Lange's Metalmark. In all model iterations, average spring precipitation had a negative effect on population growth rate response, with higher spring precipitation leading to lower counts (i.e., peak flight numbers) of the butterfly, most likely through indirect effects on the vegetation, especially favoring the invasive, non-native annual plants. Lastly, the role of atmospheric aerosol deposition on the Antioch Dunes ecosystem is examined in Chapter Three, which quantifies how much particulate matter is deposited during the peak flight period of the Lange's Metalmark. Signatures of calcium, sulfur, magnesium, and sodium were particularly high, and can be attributed directly to the Georgia Pacific gypsum plant in close proximity to the Antioch Dunes National Wildlife Refuge. The input of nitrate and ammonia is also significant. The role of these particulates with regard to soil nutrients and changing the ecosystem from oligotrophic to more eutrophic is also discussed. Recommendations are made for both management actions and further research for this imperiled sand dune ecosystem and its endangered, endemic species.