The Paleoecology of Pinnipeds on the Pacific Rim

University Of California-Santa Cruz, Santa Cruz CA

Investigators

Abstract

The Paleoecology of Pinnipeds on the Pacific Rim Intellectual Merits - Recent studies have shown that humans, including prehistoric people, play a major role in shaping the ecosystems they inhabit, and that some of the ecosystems we are familiar with today operated differently in the recent past. Historical and paleoecological data provide crucial contextual information for the conservation communities considering future management decisions, especially for species that have witnessed relatively recent population declines. Our overarching goal is to explore how environmental and anthropogenic factors interacted to generate ecological shifts on the northeastern Pacific coast over the past 5000 years. The most complete record of these changes is found in coastal archaeological sites, where the faunas of past terrestrial and marine ecosystems can be studied to investigate paleoecologic shifts. Furthermore, the recognition of major ecological shifts will be important for archaeologists attempting to decipher changes in human demography and resource utilization. In past studies, northern fur seals were studied using isotopic and archaeological data to show that the species has changed its breeding and migratory behavior over the past 1000 years. Fur seal bones were also dated to show that the collapse of local breeding colonies was not synchronous across the Pacific margin. For this study, we will investigate changes in foraging, migratory, weaning, and haul-out behavior in four different pinniped species since the mid-Holocene through construction of time series on isotopic composition, presence/absence, relative abundance, and age/sex distribution. In addition, we will develop two new methods to assess weaning age in pinnipeds. The first will use growth structures in pinniped teeth as proxies for weaning age and maternal investment. The other is a biogeochemical approach that uses changes in the N isotope ratios in bone growth series and tooth dentin. We will focus on four centers of pinniped diversity - the eastern Aleutian Islands, the US-Canadian border, the Oregon coast, and the Channel Islands. This project will include an extensive literature search and compilation of existing faunal information into a database on Holocene pinniped dynamics along the NE Pacific margin. Broader Impacts - This study will show how insights into the ecology of threatened species may be gleaned from archaeological data. This is important for species in relict populations, whose current ecology may be shaped by recent exploitation or environmental change. Three of the four species we will study are presently undergoing rapid population declines, but the causes for these declines are far from clear. This study will provide baseline data on the ecology of these species over deep time, and indicate whether or not they experienced similar declines in the past in relation to anthropogenic or environmental perturbations. We will work with conservation biologists to make our data available to those making management decisions. To this end, in winter 2004 we will co-host a conference, funded by the UC-PACRIM, which will bring together archaeologists, historians, marine mammal ecologists, conservation biologists, and social scientists. Our goal is to evaluate the archaeological and historical record of NE Pacific pinnipeds in the context of the ecology of these species today, and then to develop strategies for integrating this information into decision-making processes of conservation policy makers. A more immediate impact of this project will be the education of graduate and undergraduate students at UCSC. In addition, our prehistoric approach to marine mammal ecology was developed into a module for COSMOS (California State Summer School for Mathematics and Science) in 2002 and 2003. A diverse group of students (grades 8-12) took part in a 4-week course that integrated field, laboratory, and classroom exercises designed to introduce scholarly and motivated young people to science.