Modern Marine Bioerosion by Macroinvertebrates, Northern Gulf of California
1989; Society for Sedimentary Geology; Volume: 4; Issue: 5 Linguagem: Inglês
10.2307/3514589
ISSN1938-5323
Autores Tópico(s)Coral and Marine Ecosystems Studies
ResumoCalcareous rocks exposed in the intertidal zone of the northern Gulf of California, where the spring tide range exceeds 7 meters, are being significantly eroded by a diverse suite of endolithic invertebrates, including bivalves, sipunculans, and clionid sponges. Intertidal endoliths of two different environments near Puerto Peniasco, Sonora, Mexico, were examined. The endolithic fauna of Station Beach, on an exposed coastline subject to annual and storm-related migration of sand bodies, is quite distinctfrom that of Cholla Bay, a large, protected muddy bay. Under conditions of variable sediment cover (Station Beach), endolithic communities display higher species diversity, greater species equitability, and lower population densities than those living under relatively static conditions (Cholla Bay). Typically, there are also differences in the orientations of boring openings to the sedimentlrock surface. Based on size-frequency determinations, endolith populations in the more dynamic environments at Station Beach appear to be less mature (in terms of age). These features can be useful in interpretating paleoenvironments. Endolithic organisms are major geomorphic agents in these intertidal environments. Where conditions permit, a complex biokarst is initiated. Bioerosion rates for sipunculans and bivalves averaged over the entire affected areas range up to 0.3 m of downward erosion per 1,000 years. These rates are at the same order of magnitude as those obtained by workers investigating bioerosion in coral reefs and along sea cliffs.
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