Holocene reef growth on the edge of the Florida Shelf (reply)

Quaternary sea-level history of the United States

“…6). Submerged reefs have been identified off the Florida mainland, the Florida Keys, Puerto Rico, and St. Croix (Lidz et al, 1991(Lidz et al, , 1997Lighty et al, 1978Lighty et al, , 1982Ludwig et al, 1996;Toscano & Lundberg, 1998). Although other Holocene sea-level curves have been made (Bloom, 1983b;Kidson, 1982), the advantage of the Florida and Puerto Rico-St. Croix records is that, as with Barbados, they utilize Acropora palmata-dominated reefs.…”

“…The main species from Sand Key, Montastrea annularis, has a depth range of −3 to −80 m. Toscano & Lundberg (1999) did succeed in recovering Acropora palmata, a strictly shallowwater species, from Carysfort reef at water depths of −15.2 m (∼85,000 yr) and −15.5 m (∼92,000 yr). Because Acropora palmata grows within 5 m of the sea surface (Lighty et al, 1982), sea level could have been no lower than ∼20 m below present at these times. These data provide some measure of the possible amount of sea-level lowering during MIS 5b and the start of MIS 5a (Fig.…”

“…However, the early Holocene Florida record overlaps the Barbados record and is in broad agreement with it. Younger submerged reefs have been studied off Puerto Rico and St. Croix (Lighty et al, 1982;Macintyre, 1988;Macintyre et al, 1983). The combined records of the Florida and Puerto Rico-St. Croix reefs allow extension of the Barbados record into the Holocene and up to present sea level (Fig.…”

“…The dual dating using U-series and radiocarbon has allowed calibration of radiocarbon ages older than what was possible using tree-ring data. Modeling (Fairbanks, 1989;Bard et al, 1990), Florida (Ludwig et al, 1996;Toscano & Lundberg, 1998), and Puerto Rico-St. Croix (Lighty et al, 1978(Lighty et al, , 1982Macintyre et al, 1983). Barbados points are based on U-series ages and are corrected for tectonic uplift (Fairbanks, 1989 Stuiver et al (1998).…”

“…Paleo-sea levels for such reefs can be estimated using the shallow-water, reef-crest coral Acropora palmata because: (1) A. palmata almost always occurs in waters shallower than ∼5 m (Lighty et al, 1982); (2) its branching form allows easy recognition of whether or not it is still in growth position; (3) it grows rapidly enough that it can keep pace with a rising sea level (Buddemeier & Smith, 1988); and (4) it can be dated by both U-series and radiocarbon methods. The submerged Barbados reefs indicate that during the last-glacial maximum, sea level was ∼120 m lower than present, close to the estimate made by Shepard (1973), who used a worldwide average of the depth of the continental shelf-continental slope boundary.…”