About the Authors
School of Biological Sciences, Bangor University, Bangor, United Kingdom
The authors have declared that no competing interests exist.
Conceived and designed the experiments: RST. Performed the experiments: YSG HJ. Analyzed the data: RST YSG HJ. Wrote the paper: RST YSG. Contributed to field work and data analysis: RST. Carried out the field work, laboratory work and data analysis: YSG. Carried out all aspects of the work on the NE transects: HJ.