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Title: Depositional response to seagrass mortality along a low-energy, barrier-island coast: west-central Florida

Abstract

Analysis of aerial photographs and surficial sediment samples from the northern islands of the west-central barrier system of Florida indicates that: (1) seagrass beds in the nearshore zone have controlled onshore/longshore sand transport, and (2) resulting sedimentary accumulations within nearshore seagrass beds make differentiation of nearshore and backbarrier facies difficult. Between 1957 and 1973, an extensive seagrass community occupying the nearshore zone off Anclote Key disappeared, thus allowing the sudden and rapid onshore and longshore transport of sand. The 1000 year old barrier island lengthened 30% by recurved spit growth in this very short period of time. Although there are not direct observations, four possible causes of seagrass mortality have been postulated, and of these overgrazing as a result of the accelerated population growth of sea urchins (Lytechinus variegatus) seems to be the most likely cause. Because of the ability of seagrasses to trap fine-grained sediments, contribute organic matter, and provide for low-energy, sheltered, molluscan biocoenosis, there is little depositional difference between these nearshore and backbarrier/lagoonal facies. This work indicates that the development and destruction of benthic floral communities should be considered as a process that generates or accentuates episodicity/cyclicity in the sedimentary record. Additionally, such changes in these communitiesmore » should be expected to present a blurred distinction between certain types of coastal sedimentary facies.« less

Authors:
; ; ;
Publication Date:
Research Org.:
Univ. of South Florida, St. Petersburg (USA)
OSTI Identifier:
6613350
Alternate Identifier(s):
OSTI ID: 6613350
Report Number(s):
CONF-8510489-
Journal ID: CODEN: GAAPB
Resource Type:
Conference
Resource Relation:
Journal Name: Geol. Soc. Am., Abstr. Programs; (United States); Journal Volume: 17; Conference: 98. annual meeting of the Geological Society of America, Orlando, FL, USA, 28 Oct 1985
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; 54 ENVIRONMENTAL SCIENCES; COASTAL REGIONS; EROSION; SOIL CONSERVATION; FLORIDA; SEAWEEDS; MORTALITY; POPULATION DYNAMICS; DEPOSITION; ECOLOGY; SAND; SEDIMENTATION; SEDIMENTS; AQUATIC ORGANISMS; FEDERAL REGION IV; NORTH AMERICA; PLANTS; RESOURCE CONSERVATION; USA 580100* -- Geology & Hydrology-- (-1989); 510100 -- Environment, Terrestrial-- Basic Studies-- (-1989)

Citation Formats

Evans, M.W., Hine, A.C., David, R.A., and Belknap, D.F.. Depositional response to seagrass mortality along a low-energy, barrier-island coast: west-central Florida. United States: N. p., 1985. Web.
Evans, M.W., Hine, A.C., David, R.A., & Belknap, D.F.. Depositional response to seagrass mortality along a low-energy, barrier-island coast: west-central Florida. United States.
Evans, M.W., Hine, A.C., David, R.A., and Belknap, D.F.. Tue . "Depositional response to seagrass mortality along a low-energy, barrier-island coast: west-central Florida". United States.
@article{osti_6613350,
title = {Depositional response to seagrass mortality along a low-energy, barrier-island coast: west-central Florida},
author = {Evans, M.W. and Hine, A.C. and David, R.A. and Belknap, D.F.},
abstractNote = {Analysis of aerial photographs and surficial sediment samples from the northern islands of the west-central barrier system of Florida indicates that: (1) seagrass beds in the nearshore zone have controlled onshore/longshore sand transport, and (2) resulting sedimentary accumulations within nearshore seagrass beds make differentiation of nearshore and backbarrier facies difficult. Between 1957 and 1973, an extensive seagrass community occupying the nearshore zone off Anclote Key disappeared, thus allowing the sudden and rapid onshore and longshore transport of sand. The 1000 year old barrier island lengthened 30% by recurved spit growth in this very short period of time. Although there are not direct observations, four possible causes of seagrass mortality have been postulated, and of these overgrazing as a result of the accelerated population growth of sea urchins (Lytechinus variegatus) seems to be the most likely cause. Because of the ability of seagrasses to trap fine-grained sediments, contribute organic matter, and provide for low-energy, sheltered, molluscan biocoenosis, there is little depositional difference between these nearshore and backbarrier/lagoonal facies. This work indicates that the development and destruction of benthic floral communities should be considered as a process that generates or accentuates episodicity/cyclicity in the sedimentary record. Additionally, such changes in these communities should be expected to present a blurred distinction between certain types of coastal sedimentary facies.},
doi = {},
journal = {Geol. Soc. Am., Abstr. Programs; (United States)},
number = ,
volume = 17,
place = {United States},
year = {Tue Jan 01 00:00:00 EST 1985},
month = {Tue Jan 01 00:00:00 EST 1985}
}

Conference:
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