Epibionts of the Eastern Surf Chiton, Ceratozona Squalida (Polyplacophora: Mopaliidae), from the Atlantic Coast of Florida

The eastern surf chiton, Ceratozona squalida (Adams, 1845), inhabits the West Indian Province. On the southeastern coast of Florida, it has a clumped distribution at densities of 2.7 m-2 in the high intertidal and supratidal zones of carbonate outcrops of the Anastasia Formation. The girdle of this chiton has a dense covering of chitinous bristles to which many species of algae attach. The algal turf provides a habitat for numerous invertebrates. In total, 27 epibiotic algal and 24 invertebrate taxa were found in this study. The red alga Polysiphonia howei Hollenberg, 1945 dominated the algal turf. Other significant contributors were the brown alga Acinetospora crinita (Carmichael) Kornmann, 1953 and the green algae Chaetomorpha aerea (Dillwyn) Kützing, 1849 and Ulva flexuosa Wulfen, 1803. Mollusks and arthropods were invertebrate groups with the highest diversity of identified taxa; and the groups that ranked highest in frequency of occurrence on chitons were nematodes and copepods, the latter including a few undescribed taxa. Although larger chitons were found higher on the shore, distribution and chiton size were unrelated to percent cover of the dorsum by epibiotic algae. The present study is the most detailed to date on epibiosis of mopaliid chitons, a worldwide group for which the functional aspects of epibiosis are unknown. Understanding the functional relationship between C. squalida and its epibionts will require further descriptive and experimental study.