On the Transparency of the Sea

Collier, Albert; Finlayson, Gale M.; Cake, Edwin W.

doi:10.4319/lo.1968.13.2.0391

Cited by 9 publications

(2 citation statements)

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“…Measurements of upper ocean transparency collected with the Secchi disk have been collected using a standardized methodology since 1866 and have been related to inherent and apparent optical properties measured by modern oceanographic instruments in the context of a "theory" of the Secchi disk (see Preisendorfer 1986). Secchi disk measurements have been used to infer changes in biological productivity and phytoplankton abundance in both freshwater and oceans (Boyce et al 2010;Collier et al 1968;Falkowski and Wilson 1992;Lewis et al 1988;Tyler 1968). The linkage between observations of transparency and chlorophyll is through the dominant influence of marine phytoplankton on absorption and scattering of light in the upper ocean, similar to the basis of using ocean color radiometry in the inference of chlorophyll concentration in the upper ocean.…”

Section: Transparency Measurementsmentioning

confidence: 99%

“…Direct shipboard measurements of upper ocean Chl have been made since the early 1900s, first using spectrophotometric (Stokes 1864) and then fluorometric analyses of filtered seawater residues, and more recently through in vivo measurements of phytoplankton fluorescence (Jeffrey et al 1997;Lorenzen 1966;Yentsch and Menzel 1963). Measurements of upper ocean transparency using the standardized Secchi disk have been made since 1866 (Collier et al 1968;Tyler 1968) and have been used as a predictor of surface ocean Chl through empirically based optical equations (Falkowski and Wilson 1992;Lewis et al 1988). Although the Secchi disk is one of the oldest and simplest oceanographic instruments, Chl concentrations derived from Secchi depth observations (Z D ) are closely comparable to those estimated from direct in situ optical measurements or satellite remote sensing (Boyce et al 2010;Lewis et al 1988).…”

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Integrating global chlorophyll data from 1890 to 2010

Boyce¹,

Lewis²,

Worm³

2012

Limnology & Ocean Methods

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Understanding large-scale phytoplankton dynamics requires accurate, multi-decadal measurements of abundance and distribution. Since 1890, marine phytoplankton abundance has been assessed using a diverse range of sensors and observational platforms, and inter-calibrating these data have been challenging. Consequently, syntheses of historical phytoplankton data have been rarely attempted, and the need for accurate, long-term assessments of phytoplankton abundance and distribution is commonly acknowledged. Here, we derive quantitative indices of phytoplankton abundance from measurements of upper ocean transparency and color-calibrated with direct measurements of surface chlorophyll. The strong correlation and linear scaling of the predicted data enabled the construction of a comprehensive, globally intercalibrated chlorophyll time series from 1890 to 2010. The calibrated chlorophyll data reproduced the well-established spatial features of phytoplankton surface biomass and were strongly correlated with chlorophyll concentration derived from two independent remote sensing platforms discontinuously available since 1978. These results suggest that with careful statistical treatment it is possible to generate a globally integrated chlorophyll time series extending 120 years into the past. This database, which is available in the web appendices of this paper, may enable new insights in the areas of climate science, biogeochemical cycling, and marine ecosystem structure and functioning over the past century.

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Section: Transparency Measurementsmentioning

confidence: 99%

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confidence: 99%

Integrating global chlorophyll data from 1890 to 2010

Boyce¹,

Lewis²,

Worm³

2012

Limnology & Ocean Methods

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Are artificial reefs comparable to neighbouring natural rocky areas? A mollusc case study in the Gulf of Castellammare (NW Sicily)

Badalamenti¹,

Chemello

D’Anna³

et al. 2002

ICES Journal of Marine Science

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Mollusc assemblages of three concrete artificial reefs (ARs) in the Gulf of Castellammare were compared with those of two nearby natural reefs (NRs). The reefs were located in areas characterized by different degrees of water transparency, with average annual Secchi disk visibility ranging from clear (>20 m) to turbid waters (<6 m). In spring 1995, 28 samples of 400 cm 2 were scraped off the reefs at depths of 16-22 m (20 from ARs; 8 from NRs), which yielded a total of 116 species and 1084 specimens of molluscs. The assemblage derived from a NR in clear water showed the highest diversity, species richness, and evenness, while the highest number of specimens and dominance values were observed at an AR in turbid water. The lowest values of diversity and species richness were found at ARs in turbid water and the lowest number of specimens at a NR in turbid water. Comparison of the five reefs showed significant differences in average number of species and in diversity values, while differences in the number of specimens were not significant. Factorial correspondence analysis showed a pattern that was strongly polarized along the first axis by the NR in clear water and by the AR in turbid water. The most distinctive feature was the dominance of Bittium latreillii at AR sites. Three years after deployment, mollusc assemblages of ARs in the Gulf remain entities that are distinct from those of nearby natural reefs. However, the potential of the assemblages in terms of density of individuals is comparable to that of natural reefs.

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3.3.5 Visibility in the sea

Hoejerslev¹

Landolt-Börnstein - Group v Geophysics

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On the Transparency of the Sea

Abstract: trient samples can be tiken from the pump effluent when the water arrives from predetermined depths. STRICKLAND. '1967. The measurement of upwelling and subsequent biological processes by means of an autoanalyzer and associated equipment. Deep-Sea Res., 14: 381-389.

Cited by 9 publications

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Integrating global chlorophyll data from 1890 to 2010

Integrating global chlorophyll data from 1890 to 2010

Are artificial reefs comparable to neighbouring natural rocky areas? A mollusc case study in the Gulf of Castellammare (NW Sicily)

3.3.5 Visibility in the sea

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