Validation and interpretation of annual skeletal marks in loggerhead (Caretta caretta) and Kemp’s ridley (Lepidochelys kempii) sea turtles

Numerous studies have applied skeletochronology to sea turtle species. Because many of the studies have lacked validation, the application of this technique to sea turtle age estimation has been called into question. To address this concern, we obtained humeri from 13 known-age Kemp’s ridley (Lepidochelys kempii) and two loggerhead (Caretta caretta) sea turtles for the purposes of examining the growth marks and comparing growth mark counts to actual age. We found evidence for annual deposition of growth marks in both these species. Corroborative results were found in Kemp’s ridley sea turtles from a comparison of death date and amount of bone growth following the completion of the last growth mark (n=76). Formation of the lines of arrested growth in Kemp’s ridley sea turtles consistently occurred in the spring for animals that strand dead along the mid- and south U.S. Atlantic coast. For both Kemp’s ridley and loggerhead sea turtles, we also found a proportional allometry between bone growth (humerus dimensions) and somatic growth (straight carapace length), indicating that size-at-age and growth rates can be estimated from dimensions of early growth marks. These results validate skeletochronology as a method for estimating age in Kemp’s ridley and loggerhead sea turtles from the southeast United States

The Fractal Geometry of Mytilus edulis L. Spatial Distribution in a Soft-Bottom System

The blue mussel, Mytilus edulis L., forms dense beds that cover extensive areas of the seafloor. Mussel bed spatial pattern often appears to be complicated and highly irregular. In this study, fractal geometry was used to characterize the spatial distribution of mussels in a population from Maine, USA. Hypotheses were tested that related fractal dimension, D, to percent cover, density and spatial dispersion. The first hypothesis was that the outline of the M. edulis pattern is fractal, i.e., D values lie between 1 and 2. The second and third hypotheses were that fractal dimensions reach their highest values at intermediate levels of M. edulispercent cover and density. The fourth hypothesis was that the relationship between fractal dimension and the degree of M. edulis aggregation is negative. All four hypotheses were supported. D values of the spatial pattern within quadrats ranged from 1.36 to 1.86. Second order regression curves in the form of downward-opening parabolas were found between D and percent cover (r2=0.94) and density (r2=0.92). A negative linear regression existed between D and Morisita\u27s Index of spatial dispersion (r2=0.82). The results indicate that the complex distribution of mussels within beds is spatially ordered and has a predictable pattern that is revealed by fractal geometry

Appendix B. Population simulations.

Population simulations