Ecological Archives M085-005-A2

John R. Morrongiello and Ronald E. Thresher. 2015. A statistical framework to explore ontogenetic growth variation among individuals and populations: a marine fish example. Ecological Monographs 85:93115. http://dx.doi.org/10.1890/13-2355.1

Appendix B. Supplementary methods and results: Estimation of spatially resolved annual bottom temperature from SynTS and the HadISST1 modelled products.

We used SynTS (Ridgway et al. 2006) to estimate average annual temperature at the seafloor (Temperature) for each zone. SynTS is a spatially and temporally resolved product that models temperature-at-depth and is available semi-daily for the period 1993–2011 and at two spatial resolutions (latitude–longitude grid): 0.2° for 1993–2005 and 0.25° for 2006–2010. Average bottom depth for a 0.2 × 0.2° or 0.25 × 0.25° region centred on SynTS grid points was estimated using AGSO Bathymetry (0.01° × 0.01° spatial and 1 m depth resolution: Petkovic and Buchanan 2002). Depth estimates were restricted to between 30 and 250 m, reflecting tiger flathead's distribution and the range where most sampled fish are caught.

To account for potential spatial uncertainty in SynTS, we calculated Temperature using the depths estimated above for a 3 × 3 grid cell region (0.6° × 0.6° or 0.75° × 0.75°) centred on each SynTS grid point. The resultant overlapping temperature estimates accounted for uncertainty in depth estimation and modelled temperature-at-depth. These temperature estimates were then averaged across each zone to provide the annualised parameter values used in subsequent analyses. SynTS and bathymetry data were accessed and summarised in the statistical program R 2.15.0 (R Development Core Team 2012) using the SDODE package (Hartog and Hobday 2011). We extended our annual bottom temperature record for each zone back to 1970 by using linear relationships (Table B1) derived from the regression of available SynTS data (18 years) with modelled estimates of annual sea surface temperature from the HadISST1 1o latitude-longitude grid product (Rayner et al. 2003), accessed using ERDDAP (Simons 2011).

Temperatures in the four eastern fishing areas (NC, NSW, EBS and ETAS), CBS and WBS all increased significantly during this interval, with the largest increase in the eastern areas (range for eastern areas - 0.010–0.019 °C.yr-1; linear regressions, n = 42 years; 0.250 ≤ R² ≤ 0.556; all P ≤ 0.001). CBS and WBS increased by an average of 0.006 and 0.009 °C yr-1, respectively (linear regression, n = 42 years, R² = 0.101 and 0.161, P = 0.040 and 0.008). There was also a trend towards higher Temperatures for WTAS (0.005 °C.yr-1; linear regression, n = 42 years; R² = 0.069; P ≥ 0.094). In general, the magnitude of the temperature increase was highest for those fishing areas most strongly influenced by the East Australia Current, although rates of increase are lower than those reported for surface waters (0.023 °C.yr-1, Ridgway 2007).

Table B1. Intercept, slope, and correlation coefficient for equations relating annual SynTS temperature to annual HadISST1 temperature for each zone.

zone

intercept

slope

R²

NC

7.638

0.407

0.386

NSW

5.163

0.526

0.691

EBS

2.670

0.711

0.666

CBS

2.259

0.771

0.663

WBS

-3.557

1.157

0.638

ETAS

-0.089

0.922

0.753

WTAS

1.142

0.856

0.628

Literature cited

Hartog, J., and A. J. Hobday. 2011. SDODE: Spatial dynamics ocean data explorer. User Guide v3. CSIRO Marine and Atmospheric Research, Hobart.

Petkovic, P., and C. Buchanan. 2002. Australian bathymetry and topography grid. [Digital Dataset]. Geoscience Australia, Canberra.

Rayner, N. A., et al. 2003. Global analyses of sea surface temperature, sea ice, and night marine air temperature since the late nineteenth century. Journal of Geophysical Research-Atmospheres 108:D14.

Ridgway, K. R., J. R. Dunn, M. Cahill, and D. Griffin. 2006. SynTS: a 3D ocean observational analysis for the Australian region.in Proceedings of the 15-years Progress in Altimetry, ESA Symposium, Venice.

Simons, R. A. 2011. ERDDAP - The Environmental Research Division's Data Access Program. NOAA/NMFS/SWFSC/ERD, Pacific Grove, California, USA.


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