Land based sources of pollution//source estimates
Alina M. Szmant
szmanta at uncwil.edu
Tue Oct 2 12:43:37 EDT 2001
I can reply to your questions with regard to the upper and middle Florida
Keys, where I had a series of 9 inshore to offshore transects with sediment
traps and turbidity loggers for about 1 year. We have been able to explain
much of the turbidity and sedimentation variance by statistical correlation
with wind speed, duration and direction (C-MAN data), and thus the answer
for this area is (c). The sediments are autochonous carbonate and there
are no rivers for this area. We do get plumes of resuspended sediments
coming out of Florida Bay especially when fronts move through. A minor and
more localized source of turbidity is prop wake from large yachts and
dive/fishing boats. Inshore waters are greener and more turbid at times
due to slightly higher Chla (0.5 to 0.75 ug/l vs 0.25 or less
offshore). Suspended particulates even inshore are below 10 mg/L because
the resuspended particles are so fine and floculent.
At 09:59 AM 10/02/2001 -0500, Bob Buddemeier wrote:
>Katharina, or anyone --
>Do you have either estimates or expert-judgement opinions on the relative
>to which (or the geographic areas in which) the observed high-turbidity areas
>are primarily related to:
>a. medium or large river discharge;
>b. stream, small river or open coast runoff; or
>c. local resuspension of existing sediments?
>Getting some idea of the relative importance of these components of the
>turbidity forcing is critical to deriving impact predictions from climate,
>and land-use models.
>Katharina Fabricius wrote:
> > Another, recently published study from the Indo-Pacific province, in which
> > we looked at the effects of increasing turbidity on biodiversity:
> > Fabricius KE & De'ath G (2001) Biodiversity on the Great Barrier Reef:
> > Large-scale patterns and turbidity-related local loss of soft coral taxa.
> > Pp 127 - 144 in: Wolanski E (ed) Oceanographic processes of coral reefs:
> > physical and biological links in the Great Barrier Reef. CRC Press, London.
> > The article is best to be read in the original book which contains a CD
> > with the colour images and animations of processes. In our chapter, we
> > present a spatial model of increasing turbidtiy (originating from a
> > single-point-discharge), related to decreasing biodiversity. However I'm
> > happy to send out free reprints in paper form (black & white print) or
> > electronically (colour).
> > Abstract:
> > Spatial patterns and abiotic controls of soft coral biodiversity were
> > determined from an extensive reef surveys on the Great Barrier Reef (GBR).
> > Taxonomic inventories of soft corals, and estimates of cover of the major
> > benthos forms and of the physical environment, were obtained from 161
> > reefs, spread relatively evenly along and across the whole GBR. Reefs on
> > the mid-shelf between latitude 13° and 16° represented the "hotspot" of
> > taxonomic richness in soft corals on the GBR. Overlapping distributions of
> > in-shore and off-shore taxa maximised richness on mid-shelf reefs.
> > Taxonomic richness decreased with increasing latitude, and was low and
> > relatively even across the shelf south of 21° lat. Soft coral richness was
> > strongly depressed in areas of high turbidity. It was also weakly
> > positively related to the amount of sediment deposited, and strongly
> > increased with depth. Total cover of hard corals and soft corals was poorly
> > explained by physical and spatial variables, however both varied with
> > The findings presented here have three major management implications: (1)
> > Turbidity and sedimentation affect the generic richness of soft corals.
> > Reefs with highest soft coral richness are < 20 km from the coast, well
> > within the range of terrestrial run-off, and hence a loss of biodiversity
> > could result if turbidity increases due to land use practices which
> > generate soil loss; (2) Taxonomic composition is more strongly related to
> > environmental conditions than total hard and soft coral cover. Taxonomic
> > inventories are thus better indicators of environmental conditions and
> > human impacts than are assessments of total cover. (3) Richness and cover
> > change more within a single site between 0 and 18 m depth, than between
> > reefs hundreds of kilometers apart along the shelf at the same depth.
> > Valuable additional information can be gained in a cost-efficient way if
> > monitoring and survey programs covered several depth zones rather than a
> > single depth.
> > Regards,
> > Katharina Fabricius
> > <//\\><+><\\//><+><//\\><+><\\//><+><//\\><+><\\//>
> > Dr. Katharina Fabricius
> > Research Scientist
> > Australian Institute of Marine Science
> > PMB 3, Townsville Qld 4810, Australia
> > Fax +61 - 7 - 4772 5852
> > Phone +61 - 7 - 4753 4412 or 4758 1979
> > email k.fabricius at email.aims.gov.au
> > http://www.aims.gov.au
> > http://www.reef.crc.org.au
> > ~~~~~~~
> > For directions on subscribing and unsubscribing to coral-list or the
> > digests, please visit www.coral.noaa.gov, click on Popular on the
> > menu bar, then click on Coral-List Listserver.
>Dr. Robert W. Buddemeier
>Kansas Geological Survey
>University of Kansas
>1930 Constant Avenue
>Lawrence, KS 66047 USA
>Ph (1) (785) 864-2112
>Fax (1) (785) 864-5317
>e-mail: buddrw at kgs.ukans.edu
>For directions on subscribing and unsubscribing to coral-list or the
>digests, please visit www.coral.noaa.gov, click on Popular on the
>menu bar, then click on Coral-List Listserver.
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