Research ArticleMARINE CONSERVATION

Ghost reefs: Nautical charts document large spatial scale of coral reef loss over 240 years

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Science Advances  06 Sep 2017:
Vol. 3, no. 9, e1603155
DOI: 10.1126/sciadv.1603155
  • Fig. 1 A strong spatial gradient to coral loss in the Florida Keys.

    (A) Study area. (B). Modern and historical coral occurrences in the Florida Keys. The color of dots corresponds with the five delineated coral zones. (C) Enlarged area demonstrates the loss of coral from Florida Bay (red). (D) Enlarged area (Bahia Honda) demonstrates the loss of the nearshore patch reef (yellow) and the persistence of coral in the reef crest zone (blue). For (C) and (D), corals that no longer remain are indicated with an X. (E) Percent loss by zone. Bars represent the mean estimate of loss derived from three distance thresholds diameters (0.25, 0.5, and 0.75 km). Error bars represent the SEs across those three estimates.

  • Fig. 2 Example of nearshore coral loss near Key West, Florida.

    (A) Excerpt of Guald’s 1774 nautical chart, with locations of coral indicated with black rectangles. The inset shows an enlarged image of two adjacent historical coral references. (B) Same area today, represented by Google Earth imagery overlaid on the compiled modern benthic habitat map. Black rectangles indicate areas of coral persistence; gray rectangles indicate coral loss.

  • Table 1 Characteristics of the five reef zones, number of historical coral observations, mean depth of historical coral observations, and mean percent loss across zones.

    Percent loss represents the number of discrete historical observations in each zone that are represented by modern coral on modern benthic habitat maps. Values are mean estimates of change using three threshold distances (0.25, 0.5, and 0.75 km). na, not applicable.

    ZoneNameDepth range of corals (m)Historical coral observationsMean percent loss (SE, range)
    1Florida Bay2.1–11.4887.5 (7.2, 75–100)
    2Nearshore patch reef0.6–9.13168.8 (7.5, 61.3–83.9)
    3Offshore patch reef0.6–12.33540.0 (11.9, 22.9–62.9)
    4Reef crest1.2–14.64712.1 (6.8, 4.3–25.5)
    5Forereef12.8–58.5220 (0, na)

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/3/9/e1603155/DC1

    fig. S1. Example of method used to estimate coral persistence.

    fig. S2. Historical coral maps and zones and all historical coral observations (see table S2 for the additional data on each coral observation).

    fig. S3. The three modern coral data layers showing the differences and overlaps among them.

    table S1. Descriptive data from Gauld (1790) and the text box on the chart (fig. S1).

    table S2. All historical data, with coral observation number, map (Lower Keys versus Upper Keys), depth in meters, reef zone, and distance to nearest modern coral.

  • Supplementary Materials

    This PDF file includes:

    • fig. S1. Example of method used to estimate coral persistence.
    • fig. S2. Historical coral maps and zones and all historical coral observations (see table S2 for the additional data on each coral observation).
    • fig. S3. The three modern coral data layers showing the differences and overlaps among them.
    • table S1. Descriptive data from Gauld (1790) and the text box on the chart (fig. S1).
    • table S2. All historical data, with coral observation number, map (Lower Keys versus Upper Keys), depth in meters, reef zone, and distance to nearest modern coral.

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