Record Details
Patterns of loggerhead turtle ontogenetic shifts revealed through isotopic analysis of annual skeletal growth increments
ScholarsArchive at Oregon State University
| Field | Value |
|---|---|
| Title | Patterns of loggerhead turtle ontogenetic shifts revealed through isotopic analysis of annual skeletal growth increments |
| Names |
Ramirez, Matthew D.
(creator) Avens, Larisa (creator) Seminoff, Jeffrey A. (creator) Goshe, Lisa R. (creator) Heppell, Selina S. (creator) |
| Date Issued | 2015-11 (iso8601) |
| Note | To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by the author(s) and published by the Ecological Society of America. The published article can be found at: http://esajournals.onlinelibrary.wiley.com/hub/journal/10.1002/%28ISSN%292150-8925/ |
| Abstract | Ontogenetic changes in resource use often delimit transitions between life stages. Ecological and individual factors can cause variation in the timing and consistency of these transitions, ultimately affecting community and population dynamics through changes in growth and survival. Therefore, it is important to document and understand behavioral and life history polymorphisms, and the processes that drive intraspecific variation in them. To evaluate juvenile loggerhead sea turtle (Caretta caretta) life history variation and to detect shifts in habitat and diet that occur during an oceanic-to-neritic ontogenetic shift, we sequentially analyzed the stable isotope composition of humerus bone growth increments from turtles that stranded dead on Southeastern U.S. beaches between 1997 and 2013 (n = 84). In one-half of the sampled turtles, growth increment-specific nitrogen stable isotope (δ¹⁵N) data showed significant increases in δ¹⁵N values over each turtle's life. These data were used to provide a new line of evidence that juvenile Northwest Atlantic loggerheads exhibit two major ontogenetic shift patterns: discrete shifts (n = 24), which were completed within one year, and facultative shifts (n = 14), which were completed over multiple years (up to five). The mean difference in pre- and post-ontogenetic shift δ¹⁵N values was 4.3‰. Differences in isotopic baselines between neritic and oceanic habitats of the Northwest Atlantic Ocean make it likely these patterns are driven by a coupled change in both habitat and diet, and that facultative shifters utilize both neritic and oceanic resources within transitional growth years. Mean size and age at transition between habitats (54.2 cm straightline carapace length, SCL; 11.98 yr) was within the range of previous estimates and did not differ between discrete and facultative shifters. Our results further expand our understanding of loggerhead sea turtle life history polymorphisms and demonstrate the value of bone tissue analysis to the study of this variation. Sequential analysis of annual skeletal growth increments provides a valuable method for reconstructing long-term ontogenetic changes in foraging ecology and habitat use in long-lived, cryptic marine species. |
| Genre | Article |
| Access Condition | http://creativecommons.org/licenses/by/3.0/us/ |
| Topic | Caretta caretta |
| Identifier | Ramirez, M. D., Avens, L., Seminoff, J. A., Goshe, L. R., & Heppell, S. S. (2015). Patterns of loggerhead turtle ontogenetic shifts revealed through isotopic analysis of annual skeletal growth increments. Ecosphere, 6(11), 244. doi:10.1890/ES15-00255.1 |
