basis: we find secular salinity increases of 0.35 A± 0.34 psu in Exuma Sound and 0.5 A± 0.35 psu in TOTO that must happen coevally with the secular temperature increases to explain the discrepancies between Sr/Ca and d18Oaragonite linear temperature trends. It is evident from (4) that our reconstruction is sensitive to the gradient d18Osw/S (0.54 %psu1). Despite the significant cumulative residual error from equations (1)a€“(3) (auxiliary material), our data clearly identify salinity variation in the subsurface waters of both Exuma Sound and TOTO during the last 100 years.

direction: decrease

interpDirection: decrease

scope: climate

variable: temperature

variableDetail: subsurface, 143 m

variableGroup: temperature and salinity

scope: climate

scope: climate

basis: bohm 2000 10.1016/S0016-7037(99)00408-1

coefficient: NA

direction: negative

equilibriumEvidence: mode of skeleton formation of Ceratoporella nicholsoni suggest that these sponges precipitate aragonite close to isotopic equilibrium (bohm, 2000).

fraction: NA

inferredMaterial: seawater

integrationTime: 1

integrationTimeBasis: sclerosponges were dated using U/Th radiometric techniques and then analyzed using high resolution micromilling for oxygen isotope analysis via isotope ratio mass spectrometry and laser ablation sampling for Sr/Ca analysis via ICP-MS. Constant-growth age models constructed from U/Th dating indicate growth rates of 145 mmy1 for the Exuma sclerosponge and 172 mmy1 for the TOTO sclerosponge (auxiliary material1). The radiometric age model of the TOTO sclerosponge was tuned to annual Sr/ Ca variations after Swart et al. [2002], however because tuned age models and constant growth models are within 5% [Swart et al., 2002], the U/Th constant growth model was used for the Exuma sclerosponge.

integrationTimeUncertainty: subannual samples averaged to annual for archived data

integrationTimeUncertaintyType: U/Th dating and Sr/Ca for annual cycles to define chronology

integrationTimeUnits: year

mathematicalRelation: linear

rank: 1

scope: isotope

variable: temperature

variableGroup: Temperature

variableGroupDirection: negative

variableGroupOriginal: T_water

basis: Oxygen isotope values (d18O) are measured in %VPDB for aragonite and % SMOW for water. Ratios of Sr/Ca are measured in mmolmol1, temperature (T) is in C, and salinity (S) is in psu. Equation (3) is constructed from surface waters (<50 m) of the return flow of the N. Atlantic Gyre between 45N and 31N. During transport between these latitudes, this water mass begins adopting the properties of the SMW [Krauss, 1986; Ottens, 1991]. By combining and rearranging these equations to reconstruct the salinity record preserved in Bahamas sclerosponges,

coefficient: NA

direction: negative

equilibriumEvidence: mode of skeleton formation of Ceratoporella nicholsoni suggest that these sponges precipitate aragonite close to isotopic equilibrium (bohm, 2000).

fraction: NA

inferredMaterial: seawater

integrationTime: 1

integrationTimeBasis: sclerosponges were dated using U/Th radiometric techniques and then analyzed using high resolution micromilling for oxygen isotope analysis via isotope ratio mass spectrometry and laser ablation sampling for Sr/Ca analysis via ICP-MS. Constant-growth age models constructed from U/Th dating indicate growth rates of 145 mmy1 for the Exuma sclerosponge and 172 mmy1 for the TOTO sclerosponge (auxiliary material1). The radiometric age model of the TOTO sclerosponge was tuned to annual Sr/ Ca variations after Swart et al. [2002], however because tuned age models and constant growth models are within 5% [Swart et al., 2002], the U/Th constant growth model was used for the Exuma sclerosponge.

integrationTimeUncertainty: subannual samples averaged to annual for archived data

integrationTimeUncertaintyType: U/Th dating and Sr/Ca for annual cycles to define chronology

integrationTimeUnits: year

mathematicalRelation: linear

rank: 2

scope: isotope

variable: salinity

variableGroup: EffectiveMoisture

variableGroupDirection: negative

variableGroupOriginal: salinity_seawater

coefficient: NA

fraction: NA

rank: NA

scope: isotope

scope: climate

scope: climate

scope: climate

coefficient: NA

fraction: NA

rank: NA

scope: isotope

coefficient: NA

fraction: NA

rank: NA

scope: isotope

coefficient: NA

fraction: NA

rank: NA

scope: isotope