Download Trace Element Signatures

SPATIAL EVALUATION OF TRACE ELEMENT SIGNATURES ATTRIBUTED TO
LOCAL PHYSICAL AND OCEANOGRAPHIC PROCESSES
Matthew Smith & Jessica Nolan, Ph.D.
Introduction
Results
Hypotheses
H0: Trace element signature concentrations of nine natural
elements including, 24Mg, 208Pb, 63Cu, 59Co, 43Ca, 46Ca, 66Zn, 88Sr,
139La, and 138Ba, will not differ between each of the six
collection sites in the Gulf of Maine.
2
0.5
0.5
0
-2
-1
0
1
2
3
4
-0.5
North
LP
HB
RH
South
-2
GN
DC
NH
LP
RH
HB
0
-1.5
-1
-0.5
0
0.5
1
1.5
2
2.5
-0.5
-1
• HB and NH have consistently high concentrations of elements
compared to other sites
-1
-2
Conclusions
-1.5
Canonical Axis 1
Canonical Axis 2
Figure 2. Canonical scores (site means ± 95% confidence intervals) for linear discriminant
function analysis (LDFA) of trace element concentrations in M. edulis juvenile shell edges
collected from six sites in the Gulf of Maine in May 2013, listed from north (GN) to south
(HB). Axes represent canonical scores for all elements with values representing elements
with the highest coefficients for distinguishing between sites. (a) Canonical Axes 1 (Pb/Ca)
and 2 (Zn/Ca) (b) Canonical Axes 2 (Zn/Ca) and 3 (Cu/Ca).
Predicted Site
HB
RH
LP
NH
DC
GN
Total N
%
correct
HB
7
2
2
1
2
0
14
50.0
RH
0
8
3
1
2
0
14
57.1
LP
0
1
19
1
5
0
26
73.1
NH
3
1
1
11
0
4
20
55.0
DC
0
2
3
0
12
1
18
66.7
GN
1
0
3
0
0
13
17
76.5
Collection Sites
Overall classification success
63.1%
Table 1. Classification success of a linear discriminant function analysis of trace elemental
composition in M. edulis juvenile mussel shells across six collection sites. Trace elements
were quantified at the shell edge of juveniles (3.8 ± 0.7 mm length) of varying sample size.
Figure 1. 450km study area in the GOM
10
LA-ICPMS
Statistical
Analyses
• Laser Parameters: 90% energy, 100μm spot
size, 5μm/s at 10 Hz
• USGS standards MACS-1 and MACS-3 analyzed
3x
• 43Ca analyzed as internal standard for
correcting instrument drift
• Linear Discriminant Function Analysis
(Canonical Variate Analysis CVA)
• Ordinary One-Way ANOVA
10000
a
a
a
b
b
5000
0
HB
RH
LP
NH
Collection Site
DC
GN
Cu Ratio (mol to mol Ca)
Mg Ratio (mol to mol Ca)
a
15000
1000
a
a
a
500
a,b
b
b
Pb Ratio (mol to mol Ca)
Analytical
• Future studies should re-evaluate natural element concentrations and
compare with local water samples.
• Evaluate entire species range of M. edulis and associated pole ward
shift due to warming ocean temperatures
a
• Left valves sectioned
lengthwise, mounted, and
polished
Future Studies
1500
20000
Sampling
Figure 4. Close proximity of study
site to Coastal Highway Route 1A in
Rye, NH.
• Investigation of trace element signatures using alternative
biogeochemical methods, as well as larger sample size.
Materials/Methods
• 15-30 juveniles collected from six sites in May,
June, and July 2013
• There could be reliable differences in trace element signatures,
however, an overall classification success of 63.1% is lower
with this methodology when compared to other methods with
75-91% success (Miller, 2013).
• HB and NH show highest mean
concentrations of Cu and Pb
which may be due to a number
of factors:
•
Concentration of
population surrounding
sites
•
Roads and/or
highways near coastline
•
Concentrated industry
around mouth of Picataqua
River, nearest to site NH.
Collection
Site
Rock Harbor, MA (RH)
Horizon Beach, MA (HB)
Loblolly Point, MA (LP)
Rye, NH (NH)
Dyer Cove, ME (DC)
Grindstone Neck, ME (GN)
• Greater variation was seen in Cu and Pb concentrations among all sites
(F=7.59, 12.95, p=<0.0001) than in concentrations of Mg (F=2.80,
p=0.0206).
-1.5
DC
NH
GN
DC
NH
LP
RH
HB
Canonical Axis 3
1
Study Area
•
•
•
•
•
•
• We were able to successfully classify 63.1% of all juveniles to their
respective sites.
1.5
H0: Trace element signatures of 24Mg, 208Pb, and 63Cu do not
differ in concentration between northern and southern regions
of the Gulf of Maine.
GN
• Discriminant Function Analysis highlights three elements of greatest
distinction among the six sites: Zn, Pb, Cu (Table 1).
1
2.5
Canonical Axis 2
Larval Connectivity
• Many marine invertebrate species disperse during a planktonic
larval stage (Grahame & Branch 1985)
• Larval connectivity is the movement or exchange of individuals
between geographically isolated populations
The blue mussel, Mytilus edulis
• Ecologically and economically important bivalve species
• A recent 350 km southern range contraction (see Jones et al.,
2010) threatens local/national economies and fisheries
Trace Element Signatures
• Accumulation of natural elements in calcified structures (i.e.
shells, otoliths) during growth
• Differences in these signatures offer insight into the element
composition and natural vs. human-induced pollution
sources(Carson, 2013)
Results cont.
8
a
6
Acknowledgements
4
b
b
b
b
2
0
0
HB
RH
LP
NH
Collection Site
DC
GN
HB
RH
LP
NH
DC
GN
Collection Site
• Special thanks to Dr. Nolan and Dr. Hagerty for their help in the comprehension and data analysis of this
project.
• CREST REU UMass Boston funded by National Science Foundation Award # 1062374 to Hannigan and Christian
[OCE-GEO/OCE-Education and Human Resources (Ocean Sciences)]
• Field Team/Volunteers: Meredith Doellman, Marcus Franklin, Aishwarya Jagtap, Anna Gannett, Kelsey Magrane,
Nikelle Albright
Figure 3. Trace elemental composition of 24Mg, 208Pb, and 63Cu in shells of M.edulis
juveniles collected from six sites in the Gulf of Maine, listed south (HB) to north (GN)
(n=125). Values represent mean ratios (μmol to mol Ca46) ± 95% CI. Vertical dashed lines
within each graph distinguish between north and south location in the Gulf of Maine.
Ordinary One-way ANOVA with Tukey’s post hoc test was used with log transformed data for
all between-group analyses; means not sharing a common letter are significantly different
(p<0.05).
References:
•
Carson, H.S., Lopez-Duarte, P., Cook, G.S., Fodrie, F.J., Becker, B.J., DiBacco, C., and Levin, L.A. 2013. Temporal, spatial, and interspecific
variation in geochemical signatures within fish otoliths, bivalve larval shells, and crustacean larvae. Mar. Ecol. Prog. Ser. 473: 133-148.
•
Grahame, J. and Branch, G.M. 1985. Reproductive patterns of marine invertebrates. Oceanogr. Mar. Biol. Ann. Rev. 23: 373-398.
•
Jones, S.J., Lima, F.P., and Wethy, D.S. 2010. Rising environmental temperatures and biogeography: poleward range contraction of the blue
mussel, Mytilus edulis L., in the western Atlantic. J. Biogeogr. 37: 2243-2259.
•
Miller, S.H., Morgan, S.G., White, J.W., and Green, P.G. 2013. Interannual variability in an atlas of trace element signatures for determining
population connectivity. Mar. Ecol. Prog. Ser. 474: 179-190.