Abstract
The Hawaiian monk seal (Monachus schaundslani) is one of the most endangered species on the planet, largely due to environmental and anthropogenic influences. Analysis of the animals' tooth and bone complexes allows us to ascertain critical information regarding changes to their habitats and the effects on the animals. Tooth and bone samples from 240 naturally deceased Hawaiian monk seals were collected from the Northwest Hawaiian Island chain (NWHI) and Main Hawaiian Islands (MHI). Stable carbon, nitrogen and oxygen isotope rations (δ13C, δ15N, δ18O, respectively) provide a record of dietary and environmental change, and are reflected in the growth of teeth and bone collagen. Two hundred fifteen canine teeth were sectioned and growth layers counted to identify growth during specific years; tooth annuli dated from 1960 - 2011. These teeth represented seal occupation in the northern, central, and southern NWHI during that time. The δ13C and δ18O reveal interannual fluctuations that appear to correlate with the limited physical oceanographic data available for the region. Two hundred forty bone samples from 1910 - 2011 had collagen extracted and processed for δ13C and δ15N. Our data indicate primary productivity within the central and southern NWHI is much less than the productivity throughout the northern NWHI. Less production indicates less food and longer food webs for the organisms in these areas. The combination of all three stable isotope data indicate physical changes in the environment of the central North Pacific Ocean have a greater influence on the survival of this endangered species than direct anthropogenic influences.
Faculty Sponsors
Amy Hirons, Ph.D.
Project Type
Event
Location
Alvin Sherman Library
Start Date
4-10-2015 1:00 PM
End Date
4-10-2015 5:30 PM
Hawaiian Monk Seals: Record of Environmental Influence in an Endangered Species
Alvin Sherman Library
The Hawaiian monk seal (Monachus schaundslani) is one of the most endangered species on the planet, largely due to environmental and anthropogenic influences. Analysis of the animals' tooth and bone complexes allows us to ascertain critical information regarding changes to their habitats and the effects on the animals. Tooth and bone samples from 240 naturally deceased Hawaiian monk seals were collected from the Northwest Hawaiian Island chain (NWHI) and Main Hawaiian Islands (MHI). Stable carbon, nitrogen and oxygen isotope rations (δ13C, δ15N, δ18O, respectively) provide a record of dietary and environmental change, and are reflected in the growth of teeth and bone collagen. Two hundred fifteen canine teeth were sectioned and growth layers counted to identify growth during specific years; tooth annuli dated from 1960 - 2011. These teeth represented seal occupation in the northern, central, and southern NWHI during that time. The δ13C and δ18O reveal interannual fluctuations that appear to correlate with the limited physical oceanographic data available for the region. Two hundred forty bone samples from 1910 - 2011 had collagen extracted and processed for δ13C and δ15N. Our data indicate primary productivity within the central and southern NWHI is much less than the productivity throughout the northern NWHI. Less production indicates less food and longer food webs for the organisms in these areas. The combination of all three stable isotope data indicate physical changes in the environment of the central North Pacific Ocean have a greater influence on the survival of this endangered species than direct anthropogenic influences.
