Influence of habitat modification by rock oysters and barnacles on small-scale distribution of the tropical pulmonate limpet Siphonaria guamensis

ABSTRACT

On intertidal rocky shores, biogenic structures created by sessile organisms provide an alternative type of secondary substrate for mobile epibenthic species. The influence of habitat modification by two common sessile organisms: rock oysters Saccostrea cucullata Born, 1778 and barnacles Chthamalus spp. on small-scale (the scale of centimeters) distribution of the tropical pulmonate limpet Siphonaria guamensis Quoy and Gaimard, 1833 was investigated on four intertidal rocky shores of southern Thailand. Quadrats (100 cm²) were placed in a random fashion in both oyster and barnacle zones. The limpets were counted and their shell lengths were measured. The type of the substrate to which limpets were attached was noted. We found that limpets inhabiting unmodified rock surfaces were in higher abundance and had longer shells than those found on the shells of oysters; whereas limpets were absent from the tests of barnacles. A negative relationship between the space occupied by sessile species and limpet abundance was also detected on two of the shores studied. This suggests that there is a negative impact on siphonariid limpets from habitats modified by sessile organisms and that the process is likely to be size-dependent.

KEYWORDS:

• Rocky shore
• ecosystem engineer
• Siphonaria
• rock oysters
• barnacles

Acknowledgments

We thank Awatsaya Pimsai and Saranya Peerakietkhajorn for their help in field work and anonymous reviewers for their assistance with improving this manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Funding was provided as support for a fourth-year undergraduate project by Department of Biology, Faculty of Science, Prince of Songkla University.