DOI: 10.25921/4zv1-z503
title: NOAA/WDS Paleoclimatology - Northwest Atlantic 115 Year Coralline Algae Growth Increment Data

description: Over the past decade coralline algae have increasingly been used as archives of paleoclimate information. Encrusting coralline algae, which deposit annual growth increments in a high Mg-calcite skeleton, are amongst the longest-lived shallow marine organisms. In fact, a live-collected plant has recently been shown to have lived for at least 850 years based on radiometric dating. While a number of investigations have successfully used geochemical information of coralline algal skeletons to reconstruct sea surface temperatures, less attention has been paid to employ growth increment widths as a temperature proxy. Here we explore the relationship between growth and environmental parameters in Clathromorphum compactum collected in the subarctic Northwestern Atlantic. Results indicate that growth-increment widths of individual plants are poorly correlated with instrumental sea surface temperatures (SST). However, an averaged record of multiple growth increment-width time series from a regional network of C. compactum specimens up to 800 km apart reveals strong correlations with annual instrumental SST since 1950. Hence, similar to methods applied in dendrochronology, averaging of multiple sclerochronological records of coralline algae provides accurate climate information. A 115-year growth-increment width master chronology created from modern-collected and museum specimens is highly correlated to multidecadal variability seen in North Atlantic sea surface temperatures. Positive changes in algal growth anomalies record the well-documented regime shift and warming in the northwestern Atlantic during the 1990s. Large positive changes in algal growth anomalies were also present in the 1920s and 1930s, indicating that the impact of a concurrent large-scale regime shift throughout the North Atlantic was more strongly felt in the subarctic Northwestern Atlantic than previously thought, and may have even exceeded the 1990s event with respect to the magnitude of the warming.
description: 115 year growth increment chronology of the massive coralline alga 
Clathromorphum compactum from the Northwest Atlantic. A network of 
modern-collected and museum specimens from the shelf regions of 
Newfoundland and the Gulf of St. Lawrence, Canada, were used to 
develop a 115-year annual-resolution growth-increment width 
master chronology. 


Table 1
Correlation coefficients and significance levels of annually resolved C. compactum growth time series
from the Northwest Atlantic, Canada. Note that correlations improve when two transects within
the same sample are averaged (e.g. SJ28-L1+2), and when averaging all transects (Master).
Correlation coefficients (r) and significance levels (p) from 1950 to end of record with annually
averaged ERSSTJul-Sept (Smith et al., 2008); n = number of years used in correlation.

                                                                                                 AnnualGrowth(um)
Sample       Site                      Location           Lat. N       Long. W      Period         Average    1SD       r       p         n
SJ28-L1      Bay Bulls, St. Johns      Newfoundland       47°18.496'   52°47.354'   1933-2007        276       44     0.13    0.333       58
SJ28-L2      Bay Bulls, St. Johns      Newfoundland       47°18.496'   52°47.354'   1920-2007        251       39     0.19    0.155       58
SJ21-L2      Bay Bulls, St. Johns      Newfoundland       47°18.496'   52°47.354'   1914-2007        335       80     0.26    0.044       58
QP4-4-L1     Quirpon Island            Newfoundland       51°35.135'   55°25.490'   1941-2007        303       75     0.34    0.009       58
QP4-4-L2     Quirpon Island            Newfoundland       51°35.135'   55°25.490'   1941-2007        335       77     0.28    0.036       58
QP4-3-L1     Quirpon Island            Newfoundland       51°35.135'   55°25.490'   1933-2007        326      105      0.2    0.133       58
QP4-3-L2     Quirpon Island            Newfoundland       51°35.135'   55°25.490'   1941-2007        358      114      0.2    0.127       58
170176       Cape St. Martin           Newfoundland       50°1.5'      55°53'       1871-1963        298       84     0.09    0.761       14
64-27-C      Outer Wapitagun Island    Gulf St. Lawrence  50°11.7'     60°0.8'      1893-1963        265       73     0.07    0.824       14
64-22-H      Ile Longue, Quetachu Bay  Gulf St. Lawrence  50°16.4'     62°48'       1872-1963        220       65     0.15    0.606       14
SJ28-L1+2    Bay Bulls, St. Johns      Newfoundland       47°18.496'   52°47.354'   1920-2007        264       42     0.23    0.076       58
QP4-4-L1+2   Quirpon Island            Newfoundland       51°35.135'   55°25.490'   1941-2007        319       76     0.38    0.003       58
QP4-3-L1+2   Quirpon Island            Newfoundland       51°35.135'   55°25.490'   1933-2007        342      110     0.27    0.037       58
Master All Sites                                                                    1893-2007        296       43     0.48   0.0001       58