Sampling

• 15-30 juveniles collected from six sites in May, June, and July 2013

Analytical

• Left valves sectioned lengthwise, mounted, and polished

LA-ICP-MS

• 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

Statistical

Analyses

• Linear Discriminant Function Analysis (Canonical Variate Analysis CVA)

• Ordinary One-Way ANOVA

SPATIAL EVALUATION OF TRACE ELEMENT SIGNATURES ATTRIBUTED TO LOCAL PHYSICAL AND OCEANOGRAPHIC

PROCESSESMatthew Smith & Jessica Nolan, Ph.D.

Introduction

Hypotheses

Study Area

Materials/Methods

Results

Conclusions

Acknowledgements

Results cont.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)

Collection Sites

• Rock Harbor, MA (RH)• Horizon Beach, MA

(HB)• Loblolly Point, MA (LP)• Rye, NH (NH)• Dyer Cove, ME (DC)• Grindstone Neck, ME

(GN)

  Predicted Site   

  HB RH LP NH DC GN Total N % correct

Collection Site

               

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

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.

-1 -0.5 0 0.5 1 1.5 2 2.5

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GNDCNHLPRHHB

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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.

H0: Trace element signatures of 24Mg, 208Pb, and 63Cu do not differ in concentration between northern and southern regions of the Gulf of Maine.

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).

• 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

GN

DC

NH

LP

HB RH

North

South

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. 

• 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).

• Discriminant Function Analysis highlights three elements of greatest distinction among the six sites: Zn, Pb, Cu (Table 1).

• We were able to successfully classify 63.1% of all juveniles to their respective sites.

• 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).

• HB and NH have consistently high concentrations of elements compared to other sites

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).

HB RH LP NH DC GN0

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Future Studies

• Future studies should re-evaluate natural element concentrations and compare with local water samples.

• Investigation of trace element signatures using alternative

biogeochemical methods, as well as larger sample size.

• Evaluate entire species range of M. edulis and associated pole ward shift due to warming ocean temperatures

Figure 1. 450km study area in the GOM

Figure 4. Close proximity of study site to Coastal Highway Route 1A in Rye, NH.

• 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.