MARC 主機 00000nam 2200397 4500
001 AAI1519163
005 20130927093337.5
008 130927s2012 ||||||||s|||||||| ||eng d
020 9781267635440
035 (UMI)AAI1519163
040 UMI|cUMI
100 1 Griffin, Shelly Mae
245 10 Applying dendrochronology visual crossdating techniques to
the marine bivalve Arctica islandica and assessing the
utility of master growth chronologies as proxies for
temperature and secondary productivity in the Gulf of
Maine
300 240 p
500 Source: Masters Abstracts International, Volume: 51-02
500 Adviser: Alan D. Wanamaker, Jr
502 Thesis (M.S.)--Iowa State University, 2012
520 The work that follows is aimed at providing a more
comprehensive understanding of relationships between
growth variability within and among populations of A.
islandica in the Gulf of Maine. An essential goal of this
work is to establish the level of coherence of A.
islandica growth (that is the common growth signal) within
the Gulf of Maine. Further, the relationships between
variable growth rates and environmental conditions will be
investigated. This research presents preliminary findings
in the context of a larger project, with a goal to
establish a master shell chronology and to reconstruct
hydrographic conditions, including seawater temperatures,
for the last 1000 years in the Gulf of Maine
520 In order to determine the relationship between shell
growth and potential environmental forcings, site-specific
calibrations between growth and environmental conditions
must be developed. First, the strength of a common growth
signal (how synchronous growth is at the population level)
must be determined at each site. Then, ecologically
relevant comparisons with environmental can be
investigated. However, prior to any proxy-based climate or
environmental reconstruction, a calibration between the
proxy archive and an instrumental series is required.
Dendrochronology techniques were applied to the marine
bivalve Arctica islandica to demonstrate the benefits of
visual crossdating and replication of growth series
(growth within one shell and between multiple shells in
the same population). Prior to measuring the thickness of
annual increments, individual shell increments were
visually inspected and temporally aligned using several
visual crossdating techniques (marker years, modified list
method, and skeleton plots). Applying these techniques of
crossdating sclerochronological archives resulted in
precisely dated and a highly replicated master shell
chronology (average expressed population signal = 0.94;
series intercorrelation =0.76) from a site within the
central Gulf of Maine (northwestern Atlantic Ocean). Such
chronologies can then be more confidently compared to
environmental and climate indices. For example, the master
shell chronology developed from this population shows a
strong relationship with spring (MAM) local bottom water
temperatures (r = −0.81, p < 0.0001). This strong
proxy/instrumental relationship rapidly diminishes with
the introduction of chronology errors (i.e., errors that
occurred prior to crossdating). Two types of errors,
typically encountered when measuring increment widths in
bivalves, were introduced to the absolutely dated age
model. We then illustrate how these introduced errors
result in decreased agreement in the proxy/instrumental
series along with a corresponding decrease in statistical
of the relationship. This finding illustrates that poorly
developed age models (even with 1–3 errors over 60
years) will decrease the skill of the proxy archive to
accurately reflect environmental conditions. Visual
crossdating and replication of sclerochronological growth
series is an essential step in the development of accurate
master chronologies. This procedure is especially
important during the process of calibrating a proxy
archive with an environmental data series
520 To investigate ocean and ecosystem variability within the
Gulf of Maine two master shell chronologies were
constructed from annual growth increments of the marine
bivalve Arctica islandica from two sites (site 1: 44°
26’ 9.829” N, 67° 26’ 18.045”
W; site 2: 43° 42’ 54” N, 69° 44&
rsquo; 52” W). Both chronologies are statistically
robust (site 1- series intercorrelation = 0.70, EPS =0.93,
from 1954–2008; site 2 - series intercorrelation =
0.76, EPS = 0.94 from 1783-2009) showing strong
synchronous growth within each site. The master shell
chronologies are statistically comparable to A. islandica,
tree-ring, and otolith master chronologies from which
environmental reconstructions have been made. Both master
shell chronologies were compared with nearby instrumental
temperature records from Boothbay Harbor, Maine and
Canadian Prince 5 station. A statistically strong (r = &
minus;0.81) and significant (p < 0.0001) relationship with
site 2 master shell growth and Boothbay Harbor spring
(MAM) bottom water temperatures was found. Using the full
length of the site 2 master shell chronology, Boothbay
Harbor MAM bottom water temperatures were reconstructed
(1783 to 2009), yielding high year-to-year, decadal, and
multi-decadal variability. A third chronology was
constructed by averaging master shell chronologies from
site 1 and site 2. The combined chronology was compared
with continuous plankton recorder (CPR) time-series from
the Gulf of Maine. A significant correlation (r = 0.49; p
< 0.0002) exists between the combined chronology and the
annual abundance of Calanus finmarchicus, which is the
dominant zooplankton species for this region. Although
each site master shell chronology individually yielded a
significant relationship with the C. finmarchicus
abundance, the combined shell chronology outperformed each
site-specific shell chronology. This result illustrates
the potential advantage of combining master shell
chronologies, which in this study minimized local noise
and enhanced the regional-scale productivity signal. Based
on the robust and statistically significant relationships
between master shell chronologies with temperature and
secondary productivity indicators, these master shell
chronologies developed in the Gulf of Maine have the
potential to hindcast past ocean conditions beyond the
instrumental record
590 School code: 0097
650 4 Geology
650 4 Marine Geology
650 4 Paleoclimate Science
690 0372
690 0556
690 0653
710 2 Iowa State University.|bGeological and Atmospheric
Sciences
773 0 |tMasters Abstracts International|g51-02(E)
856 40 |uhttps://pqdd.sinica.edu.tw/twdaoapp/servlet/
advanced?query=1519163
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