Holocene saline lake history, San Salvador Island, Bahamas

Abstract

The lakes of San Salvador Island, Bahamas, occupy sinkholes and curvilinear depressions between dune ridges. Most lakes have maximum water depths of 2 m. They lie approximately at sea level and are saline to varying degrees. Sea water from the surrounding ocean infiltrates the lake basins through permeable carbonate bedrock. The average salinity of lake waters is controlled by the degree of development of the conduit system, the size of the basin, its elevation relative to sea level, rainfall, and the presence of local freshwater lenses.Ostracodes, which are abundant in these lakes, define three salinity-controlled assemblages: freshwater, marine, and euryhaline. The euryhaline assemblage, consisting of four species, predominates, with a salinity range of 10 to almost 100 ppt.Lake basins typically contain as much as 2 m of unconsolidated Holocene sediment resting on Pleistocene carbonate bedrock. Where different assemblages are present, varying ostracode abundances can be used to subdivide cores into zones. Longer cores exhibit four zones, which are apparently correlative from lake to lake. Consistent ostracode assemblages indicate prevailing or typical salinities in these zones. Different lakes reveal parallel salinity histories. Salinity fluctuations through time are likely to have been caused by changing climate or sea level.Initial study of salinity-controlled Mg concentrations in the carapace of Cyprideis americana gives estimates of salinity similar to those interpreted from assemblages of ostracodes. Salinity minima, which occur at zone boundaries, correlate with Holocene low stands of sea level. In lakes where only the euryhaline assemblage is present, salinity minima may be used for correlation.

Changes in growth rates of oral jaw elements produce evolutionary novelty in bahamian pupfish

“…Wild fish were collected from San Salvador Island, Bahamas in 2013 using hand nets and minnow traps baited with cat food. San Salvador Island contains numerous inland hypersaline lakes that are hydrostatically connected to the ocean through conduits and a porous limestone karst bedrock (Titus, ; Hagey and Mylroie, ; Teeter, ; Turner et al, ; Rothfus, ). While the omnivore pupfish, C. variegatus , can be found in all habitable lakes on the island, the scale‐biter, C. desquamator , and the hard prey specialist, C. brontotheroides , occur in a subset of these same lakes (Turner et al, ; Martin and Feinstein, ).…”

Reproductive isolation among endemic pupfishes (Cyprinodon) on San Salvador Island, Bahamas: microsatellite evidence

“…Multiple lines of evidence, including C‐14 analysis (Kwolek, 1985), indicate that the lakes date from between 3500 and 6000 years BP (Pacheco & Foradas, 1986; Godfrey et al. , 1994; Hagey & Mylroie, 1995; Teeter, 1995; Carew & Mylroie, 1997). For example, the first red mangrove ( Rhizophora sp.)…”

“…Descriptions of the geology, hydrography, and ecology of all of these localities are included in broader discussions of the San Salvador lakes by Gerace (1973), Gerace et al. (1983; Gerace, Ostrander & Smith 1998), Teeter (1983, 1995), Teeter & Bain (1984), Curran et al. (1985), Carew & Mylroie (1994), Hagey & Mylroie (1995) and Godfrey et al.…”

Sea level rise and inundation of island interiors: Assessing impacts of lake formation and evaporation on water resources in arid climates

“…SEAWAT currently lacks the capability of directly simulating lakes. We thus simulate lakes as depressions by increasing the porosity to 100% and the hydraulic conductivity by a factor of 4 in a selected set of top cells of the model grid, so that the lake depths are 1 m, similar to Bahamian lakes [ Teeter , ]. This modeling approach allows water and solutes to be transported by groundwater flow into cells representing lakes, allows for approximately completely mixed conditions in the lake cells, and allows water to be discharged from lakes by evaporation.…”