Title: **Paleocology of deep-sea corals in the Gulf of Mexico and
Western Atlantic: deciphering the high resolution marine climate history
over the last three thousand years**

Statement of Problem: In 1785, James Hutton, recognized that the
formation of geologic features could be understood by studying the
processes active at present. His axiom, "the present is key to the
past," has become the foundation of geologic research. To understand the
forces which control climate change, the 0corollary of this axiom "the
past can be used to understand the present" has been employed for the
last few decades. Modern instrumentation has recorded climate change on
an inter-annual time scale, but is insufficient to record climate change
over centuries. Our knowledge of climate change is based on studies of
ice cores, tree rings, shallow water corals, and varved sediments. These
are predominantly derived from terrestrial data. The oceanic records of
climate change presently available have limited resolution. Recently, it
has been discovered that deep-water corals, (black corals), contain
high-resolution records of environmental changes in the ocean. As these
are slow growing, they contain an extended temporal record that rivals
tree rings and other terrestrial recorders of climate change. This
project will focus construction the climate record for the ocean using
the information locked in the chemistry of these corals. Black corals,
or Antipatharians, are colonial animals, are found in all oceans, but
are most common in deepwater habitats of tropical and subtropical seas.
Black corals are carnivores. The fan-like growth patterns that
characterize colonies of some species are thought to be an adaptation
for efficient feeding in directional current flows. Firmly attached to
the seafloor, colonies are swept by currents that move animal plankton
over the polyps. While relatively little is known about the life cycle,
it has been determined that these corals grow at a very slow rate. In a
living black coral, the skeletal framework is covered with a thin veneer
of tissue, called the cenosarc. This layer secretes the tightly-layered
central skeleton of horn-like protein. It has been determined that these
distinct layers of protein are produced annually. The annual growth
bands can be counted, separated, and analyzed chemically. Thus these
animals record the environmental changes of the surrounding ocean. USGS
recently discovered a black coral from the Atlantic that is over 3000
years old with others that are 1000 years old. Carbon, nitrogen, sulfur
isotopes, and metals in the growth rings reflect fluxes that are related
to environmental change. Hence, this study proposes to use these corals
to document a chronology of environmental change. Together, the
chemistry of these corals define high-resolution changes in temperature,
salinity (including thermal-hyaline circulation patterns), and the
chemistry of the surrounding sea over time.

Objectives: Objectives of this project are to use the structure and
chemistry encapsulated in the annual bands of deep-water corals to
construction the paleo-ecology of deep-water habitats and use the
variation in trace metals and isotopes in the bands to construct a
high-resolution history of climate change in the Gulf of Mexico and
Western Atlantic Ocean. Develop a fundamental understanding of processes
that govern interactions among climate, earth surface processes, and
marine and terrestrial ecosystems.

Work Strategy: The antipatharians collected have been photographed and
identified. Using an existing potassium hydroxide technique, the annual
layers will be separated. These will be dated via Pb-210 and carbon-14.
As the samples are derived from annual bands, carbon-14 determinations
will establish a calibrated chronology for the regions from which the
specimens are found, defining the reservoir factor for the surrounding
ocean. In addition, the bands will be analyzed for carbon, nitrogen, and
sulfur isotopes and trace metals. The carbon isotopes will track changes
in the carbon cycle; the nitrogen and sulfur isotopes with track changes
in tropic level in the surround sea. In addition to the isotopic
analysis, trace metals and the isotopes of zinc, cadmium and iron will
be measured by ICP/MS and ICP/MC. They and the isotopes of zinc, iron
and cadmium will track sources of sediment.

Relevance and Impact: This study will provide fundamental,
high-resolution data on climatic changes in the Gulf of Mexico and
Eastern Atlantic Ocean. This information will form the basis for better
understanding the forces that drive short-term climate changes. Also,
knowledge of the deepwater environment is basic to understanding habitat
characteristics and long-term physical and chemical characteristics, as
well as life-history on relatively rare, long-lived, deepwater taxa.
Such information will be used to make informed decisions that are needed
to protect living resources. Thus this study will provide information
germane to the management of deep-water habitats while providing
high-resolution climatic histories which are important in the
development of predictive climate models.\
Partnerships: University of North Carolina, Minerals Management service,
and NOAA.