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Biogenic Reworking of Intertidal and Subtidal Sediments in Barnstable Harbor and Buzzards Bay, Massachusetts

Rhoads, Donald C.

The Journal of geology, 1967-07, Vol.75 (4), p.461-476 [Periódico revisado por pares]

University of Chicago Press

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  • Título:
    Biogenic Reworking of Intertidal and Subtidal Sediments in Barnstable Harbor and Buzzards Bay, Massachusetts
  • Autor: Rhoads, Donald C.
  • Assuntos: Burrowing ; Harbors ; Ingestion ; Limnology ; Moorings ; Oceanography ; Sand ; Sediments ; Tidal flats ; Worms
  • É parte de: The Journal of geology, 1967-07, Vol.75 (4), p.461-476
  • Descrição: Biogenic reworking of marine sediments is described from intertidal deposits in Barnstable Harbor and subtidal sediments of Buzzards Bay, Massachusetts. Reworking activities of three polychaete species were studied in Barnstable Harbor: Clymenella torquata, Pedinarla goiddii, and Amphitrite ornata. Sediment reworking by these tube-dwelling annelids is primarily a vertical and lateral size-sorting process. The selective ingestion and transportation of sand and smaller-sized particles leads to the formation of biogenically graded deposits. Clymenella is estimated to ingest 274 ml. of sediment per worm per year. Pectinaria ingests 400 ml. of sediment per worm per year according to Gordon (1966). The annual reworking rate of Amphitrite remains unknown, but probably exceeds that of Clymenella and Pectinaria. Five stations in Barnstable Harbor were artificially laminated with colored sand horizons to observe biogenic reworking at depth within the sediment. After 2 months, differences in intensity of reworking between stations appeared to be related to faunal composition rather than to faunal density. Tidal flats populated by low densities of predators were more highly reworked than stations populated by relatively high polychaete densities. Disturbance of the artificial laminae was found to be most intense in the upper 10 cm. of sediment (near surface predators). Reworking by polychaetes extended to a depth of 30 cm. Artificial lamination of subtidal Buzzards Bay sediment revealed extensive reworking of the upper 2-3 cm. of sediment after a 2-month period. Infaunal activity was restricted to a depth of 10 cm. Yoldia limatula (bivalve) was primarily responsible for extensive near-surface reworking. Nucula proxima (bivalve) and Nepthys incisa (polychaete) are also important reworking organisms in Buzzards Bay. Rates of biogenic reworking recorded in this study indicate the importance of benthic organisms as agents of sediment diagenesis. Differences in burrowing depth between intertidal and subtidal environments may prove valuable for paleoecologic determination of onshore-offshore facies relationships. Deep vertical burrowing (to a depth of 30 cm.) is common in nearshore environments, especially in intertidal sediments. Shallow horizontal burrowing (to a depth of 10 cm.) is best developed in offshore level bottoms. Burrowing attitude may be observed in vertical thin sections of sediments that otherwise lack fossils, permitting paleobathymetric analysis of un-fossiliferous as well as fossiliferous deposits.
  • Editor: University of Chicago Press
  • Idioma: Inglês
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  • Realização: ABCD-USP USP   Logos de Redes Sociais: Freepik

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