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

Conference · Tue Jan 01 04:00:00 EST 1985 · Geol. Soc. Am., Abstr. Programs; (United States)

OSTI ID:6613350

Evans, M W; Hine, A C; David, R A; Belknap, D F

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.

• Research Organization: Univ. of South Florida, St. Petersburg (USA)
• OSTI ID: 6613350
• Report Number(s): CONF-8510489-
• Conference Information: Journal Name: Geol. Soc. Am., Abstr. Programs; (United States) Journal Volume: 17
• Country of Publication: United States
• Language: English

Related Subjects

510100 -- Environment
Terrestrial-- Basic Studies-- (-1989)
54 ENVIRONMENTAL SCIENCES
58 GEOSCIENCES
580100* -- Geology & Hydrology-- (-1989)
AQUATIC ORGANISMS
COASTAL REGIONS
DEPOSITION
ECOLOGY
EROSION
FEDERAL REGION IV
FLORIDA
MORTALITY
NORTH AMERICA
PLANTS
POPULATION DYNAMICS
RESOURCE CONSERVATION
SAND
SEAWEEDS
SEDIMENTATION
SEDIMENTS
SOIL CONSERVATION
USA