11th ICRS Abstract book - Nova Southeastern University

Oral Mini-Symposium 19: Biogeochemical Cycles in Coral Reef Environments
19-13
Water Quality Monitoring Along The Florida Reef Tract: Assessment Of Dissolved
Organic Matter Sources And Compositional Variations
Youhei YAMASHITA* 1 , Joseph BOYER 1 , Diane WILLIAMS 1 , Rudolf JAFFE 1
1 Southeast Environmental Research Center, Florida International University, Miami, FL
The characterization of DOM can contribute to understanding its ecological roles in
diverse aquatic environments. This carbon pool is highly reactive and influences
ecosystem function through many biogeochemical reactions and is known to fuel the
microbial loop, particularly in oligotrophic environments. Thus in addition to its quantity
it is important to determine its source and characteristics (i.e. quality) in large scale and
long term water quality monitoring programs. DOM in coastal regions is derived from a
variety of sources, including autochthonous planktonic as well as allochthonous
terrestrial and anthropogenic sources and its quality has been found to strongly depend on
sources and physical and biological processes. This study reports on preliminary data on
DOM quality along the Florida Keys reef tract. The concentration of dissolved organic
carbon (TOC) and dissolved organic nitrogen (DON) in addition to optical properties of
DOM were determined at over 100 field stations ranging from the upper Florida Keys to
the Dry Tortugas National Park in the Gulf of Mexico on a quarterly schedule. DOM
quality was determined through excitation emission matrix (EEM) fluorescence in
combination with parallel factor analysis (PARAFAC). Results show that the DOM
associated with the South Florida coral reef community is derived from a combination of
sources including autochthonous microbial sources as well as terrestrial and
anthropogenic sources, both from the Florida Keys as well as through water exchange
with Florida Bay and the Florida Shelf. The spatial variability confirmed potential source
assignments of the DOM.
19-14
Organic Matter Cycling in Tropical Coral Reef Ecosystems: The Role Of The Reef
Framework And Its Biota, Dominated By Encrusting Sponges.
Jasper M. DE GOEIJ* 1,2 , Joost W. VAN DAM 1,2 , Hubèrt EIJKELENBOOM 1,2 , Eric
H.G. EPPING 3 , Fleur C. VAN DUYL 1
1 Department of Biological Oceanography, Royal Netherlands Institute for Sea Research,
Den Burg, Netherlands, 2 Caribbean Research & Management of Biodiversity, The
CARMABI Foundation, Willemstad, Netherlands Antilles, 3 Department of Marine
Chemistry & Geology, Royal Netherlands Institute for Sea Research, Den Burg,
Netherlands
The coral reef framework is a major sink of organic matter. The removal of organic
carbon by framework cavities, with volumes ranging from 50-250 dm 3 , in reefs of the
Berau area, East-Kalimantan, Indonesia and in the reefs of Curaçao, Netherlands Antilles
were in the range, or even exceeded the estimated average gross primary production of a
coral reef ecosystem. Dissolved organic carbon removal rates by coral cavities were on
average 1 to 2 orders of magnitude higher than particulate organic carbon removal rates.
A mass balance for carbon (C), nitrogen (N) and phosphorus (P) was constructed for
Curaçaoan coral reef framework cavities. The major fate of C was assimilation,
suggesting a rapid turnover of matter for a net increase in biomass close to zero. Relative
to C and N, P was selectively retained from the reef water flushing the coral cavities. To
directly link the nutrient cycling within the reef framework with the cryptic biota, the
organic carbon fluxes were determined for the four dominant communities: (1) Sponge,
(2) calcareous algae, (3) sediment, and (4) bare substrate – together accounting for, on
average, 88% of the surface of the cavities. Evidently, sponges play a key role in the
carbon cycling within the reef framework. Sponges, with an average cavity surface cover
of approximately 25%, represented approximately 75% of the total organic carbon flux
by coral cavities. Dissolved organic carbon accounted for more than 90% of the total
organic carbon removal rate by encrusting sponges. We conclude that the coral reef
framework is an important habitat for decomposition and (re)cycling of - to large extent
dissolved - organic matter within the coral reef ecosystem. The nutrient cycling is mainly
accounted for by a thin veneer of, mostly encrusting, sponges.
19-15
Seasonal Carbon Production And Topographic Features in Sesoko Beach Reef, Okinawa,
Japan
Hiroyuki FUJIMURA* 1 , Takashi FUKUNAGA 1 , Kyouhei ISHIKAWA 1 , Koujiro
SHIMADA 1 , Tomihiko HIGUCHI 1 , Tamotsu OOMORI 1 , Yoshikatsu NAKANO 2 , Tatsuo
NAKAI 3 , Beatoriz CASARETO 4 , Yoshimi SUZUKI 5 , Takuji ITO 6
1 Department of Chemistry, Biology and Marine Science, University of the Ryukyus, Okinawa,
Japan, 2 Sesoko Station Tropical Biosphere Research Center, University of the Ryukyus,
Okinawa, Japan, 3 Kokushikan University, Tokyo, Japan, 4 Laboratory of aquatic science
consultant (LASC), Tokyo, Japan, 5 Shizuoka University, Shizuoka, Japan, 6 Mitsubishi
corporation, Tokyo, Japan
Owing to the global warming and environmental change, coral reefs have been under a serious
threat of degradation in the world. In order to understand the present state of coral reefs and
predict the future changes, it is important to study a seasonal variation of community carbon
metabolism and topographic features in coral reefs. We observed the community carbon
metabolism of photosynthesis and calcification every month in Sesoko Beech reef in
northwestern part of Sesoko Island, Okinawa, Japan. Most of the corals damaged by mass coral
bleaching in 1998 and has not recovered yet. Topographically and biologically different sites
were selected as representatives of the reef community in Sesoko. We took water samples every
30min for pH, dissolved oxygen and total alkalinity during slack water periods when the
shallow lagoon water (< 80cm) was isolated from offshore. Only two narrow channels is existed
and small portion of inside water is flowing out to offshore during low tide. Organic and
inorganic carbon productions were estimated from the change in total alkalinity (AT) and total
dissolved inorganic carbon (CT) with time. CT was calculated from pH and total alkalinity using
a carbonate equilibrium in seawater. Gross primary production was 300-400 mmol/m 2 /d and
respiration was 150-300 mmol/m 2 /d. P/R ratio varied 1.3-1.9, indicating the high photosynthesis
rate of fringing reef in Ryukyu Islands. While the high organic carbon production, inorganic
carbon production of calcification was 45-55 mmol/m 2 /d which is lower value than the other
reefs of Okinawa reported before the bleaching. This suggests that the Sesoko coral reef has
significantly degraded since coral bleaching in 1998. Further observations are needed to detect
the early change in recovery or more additional degradation in the future.
19-16
Temporal Variations in Dissolved Inorganic Nitrogen, Dissolved Gas And Volatile
Organic Matter Fluxes Resulting From Sponge Respiration And Microbial
Transformations On Conch Reef, Florida Keys (Usa)
Christopher MARTENS* 1 , Niels LINDQUIST 2 , Howard MENDLOVITZ 3 , James HENCH 4 ,
Richard CAMILLI 5 , Anthony DURYEA 6 , Brian POPP 7 , Patrick GIBSON 3 , Melissa
SOUTHWELL 3,8 , Jeremy WEISZ 9 , Nyssa SILBIGER 3
1 Marine Sciences, UNC-Chapel Hill, Chapel Hill, NC, 2 Institute of Marine Sciences, UNC-
Chapel Hill, Morehead City, NC, 3 UNC-Chapel Hill, Chapel Hill, NC, 4 Stanford University,
Stanford, CA, 5 Woods Hole Oceanographic Institution, Woods Hole, MA, 6 Monitor Instruments
Company, Cheswick, PA, 7 University of Hawaii at Manoa, Honolulu, HI, 8 UNC-Wilmington,
Wilmington, 9 Old Dominion University, Norfolk, VA
High nutrient element fluxes from sponges resulting from rapid respiration rates of dissolved
and particulate organic matter likely dominate dissolved inorganic nitrogen (DIN) cycling on
the Florida Keys reefs and should be dominant in coral reef ecosystems around the world
featuring significant sponge biomass. The barrel sponge Xestospongia muta accounts for
approximately 60% of sponge biomass in a 600m2 area on Conch Reef off Key Largo, and
generates net DIN fluxes exceeding 10 mmol/m2/day, far greater than fluxes from coral
substrate and sediments. Respiration by X. muta generally results in a 5-15% oxygen drawdown
in the huge volumes of ambient water pumped through its tissues. This sponge and many other
plentiful species have a single exit point for all exhaled water, allowing for rigorous in situ
quantification of filtration rates and net chemical fluxes utilizing a variety of underwater
instrumentation. During two 2007 missions utilizing the NURC/UNCW Aquarius Reef Base
undersea observatory, chemical transformations and fluxes resulting from X. muta respiration
were quantified continuously for periods of hours to weeks by coupling chemical sensor
measurements with acoustic Doppler velocimetry (ADV) pumping rate measurements. Three
different instrument arrays, including a newly designed, in situ membrane inlet mass
spectrometer (MIMS), were utilized to continuously measure dissolved gases including O2
(mass 32), N2 (28), Ar (40) and CO2 (44,45) plus a variety of volatile dissolved organic
molecules. The stoichiometries of O2 consumption, CO2 production and DIN release were
utilized to quantify the role of barrel sponges in reef respiration and C and N cycling and to
identify potential biogeochemical transformations such as the uptake of dissolved organic
matter, N2 fixation and denitrification. The new capability to measure fluxes of volatile organic
molecules from sponges using MIMS should provide novel insights into the chemical
interactions of sponges with other reef ecosystem inhabitants.
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