Inland lakes and ponds (view of Northeast Arm Lake from atop Dixon Hill Lighthouse; looking W) - San Salvador Island has numerous inland bodies of water. Christopher Columbus remarked upon them during his visit in October 1492.  These ponds and lakes can have freshwater, brackish water, hyposaline water, normal marine-salinity water, or hypersaline water.  Many of these lakes have aquatic biotas quite distinctive from adjacent lakes.




Much of the northeastern San Salvador lakes information presented below is synthesized from Godfrey et al. (1994) and Mylroie & Carew (2008) (see citations at bottom of page).







Reckley Hill Pond (looking ~NW) - this hyposaline to hypersaline lake just southeast of the Bahamas Field Station is also known as Reckley Hill Settlement Pond or Merrill’s Pond or Coast Guard Pond.  Reported water salinities range from 18 to 66 ppt, averaging around 47 ppt (cf. normal marine water at about 35 ppt).  I measured 45 ppt salinity here on 24 March 1999.



Batophora oerstedi Agardh, 1854 (= dark green fuzzy structures) & Acetabularia crenulata Lamouroux, 1816 (= whitish to whitish-green cup structures on thin stalks) (above & below).  The most common algae seen along the southern shoreline of Reckley Hill Pond are two green algae species - fuzzy finger algae (Batophora oerstedi - Plantae, Chlorophyta, Dasycladales, Dasycladaceae) and white mermaid’s wine glass algae (Acetabularia crenulata - Plantae, Chlorophyta, Dasycladales, Polyphysaceae).



Molluscan lake sediments - Reckley Hill Pond lakefloor sediments are overwhelmingly dominated by mollusc shells and broken mollusc shells.  Most of the shells seen above are batillariiid snails (black & white stripes - Batillaria minima), cerithiid snails (Cerithium lutosum), potamidid snails (brown - Cerithidea costata), and bivalves (whitish-gray - Anomalocardia auberiana & Polymesoda maritima).

Note the small, white-colored, coiled structures attached to the large, black leaf at left - those are Spirorbis worm tubes (Annelida, Polychaeta, Sabellida, Spirorbidae).



Reckley Hill Pond Conduit - this lake drain occurs near the southeastern corner of the lake.  Reckley Hill Pond experiences tides.  Because of the pond’s elevation, tidal inflows occur only during and near times of spring high tides (= extra high-high tides).  Reported salinites of water entering the lake from this conduit are 36 to 38 ppt - just above normal marine values.  The rocks around the conduit are limestones of the Cockburn Town Member of the Grotto Beach Formation (lower Upper Pleistocene, Sangamonian, MIS 5e, 119-131 k.y.).



Reckley Hill Pond Water Cave - this is the entrance to one of three small caves near the eastern shore of the lake, just northeast of Reckley Hill Pond Conduit (see above).  Published research has shown that a small stream flowing through this particular cave leads to the Reckley Hill Pond Conduit.  The rocks here are limestones of the Cockburn Town Member of the Grotto Beach Formation (lower Upper Pleistocene, Sangamonian, MIS 5e, 119-131 k.y.).





Crescent Pond (a.k.a. No Name Pond) (looking ~WSW) - this gently curving, E- to ENE-trending, inland lake in northeastern San Salvador Island occurs in a depression between two Pleistocene-aged sand dune ridges (now lithified to aragonitic calcarenite limestones).

Crescent Pond has slightly higher-than-normal marine salinities at 36 to 38 ppt.  I measured 38 ppt here on 22 March 2009.  The pond has three significant lake drains (conduits) on the southern side, near its western end.  Water flow from these conduits into the lake is moderately energetic during flood tides, resulting in visible boils at the lake surface.



Isognomon alatus (Gmelin, 1791) - the thin, black-colored shells encrusting Crescent Pond’s shoreline rocks here are mangrove oysters (Animalia, Mollusca, Bivalvia, Pteroida, Isognomonidae).  The greenish algae are Cladophoropsis macromeres Taylor, 1928 (Plantae, Chlorophyta, Siphonocladales, Boodleaceae).



Arenicola cristata Stimpson, 1856 - egg mass of the Atlantic lugworm (Animalia, Annelida, Polychaeta, Capitellida, Arenicolidae) in eastern Crescent Pond.





Pain Pond (above & below) (looking ~WNW above & looking ~SW below) - Pain Pond is a small lake having a lake drain/conduit on the eastern side, along a “swiss-cheese limestone” rocky shoreline.  The water’s salinity is near-normal marine, around 36 ppt.  I measured 36 to 37 ppt salinity on 24 March 1999.

Easily observed organisms include Cerithium snails, Arenicola cristata (Atlantic lugworm) egg masses, and Cyprinodon variegatus sheepshead minnows.



Codakia limestone just west of Pain Pond (camera lens for scale).  The large fossil shells are the tiger lucine clam, Codakia orbiculata (Linnaeus, 1758).  This is part of the Cockburn Town Member of the Grotto Beach Limestone (lower Upper Pleistocene, Sangamonian, MIS 5e, 119-131 k.y.).





Moon Rock Pond (looking ~SE) - the name of this lake is in reference to the extensive “swiss cheese limestone” outcrops along much of its shoreline, especially on the northern side (see below).  The large-scale limestone macroporosity somewhat resembles craters on the Moon.  I measured 39 ppt salinity here on 22 March 2009.

Whitish, fine-grained aragonite lakefloor sediments are common in this pond.  The sediments appear to originate from CaCO3 precipitation events in the lake following rainstorms.  During such events, Moon Rock Pond’s waters turn milky white (for the full story, see Davis in Godfrey et al., 1994, p. 26).



Codakia limestone at the northeastern corner of Moon Rock Pond.  The large fossil shells are the tiger lucine clam, Codakia orbiculata (Linnaeus, 1758).  This is part of the Cockburn Town Member of the Grotto Beach Limestone (lower Upper Pleistocene, Sangamonian, MIS 5e, 119-131 k.y.).



Moon rock (above & below) along the northern shoreline of Moon Rock Pond.  The limestone’s secondary macroporosity has been attributed to groundwater aggresivity at the mixing zone of lake water and meteoric-derived groundwater descending toward the lake from the hill to the north.  A lithified dune ridge of Pleistocene-aged aragonitic calcarenite limestones occurs on the northern side of this pond, separating it from Crescent Pond (see above).

Mixing zone groundwater aggresivity is the same causal factor behind development of flank margin caves in the Bahamas.



Batillaria snails (Animalia, Mollusca, Gastropoda, Batillariidae) on rocky western shoreline of Moon Rock Pond.





Wild Dilly Pond (above & below) (looking ~SW) - this small, ~flat-bottomed lake between Moon Rock Pond and Oyster Pond is lined by subvertical limestone walls.  The rocks are Cockburn Town Member of the Grotto Beach Formation (lower Upper Pleistocene, Sangamonian, MIS 5e, 119-131 k.y.).  The lake drain/conduit is along the limestone wall near the southwestern corner of the pond.  Water salinities are ~normal marine.

The subvertical grooves on the upper part of the sloping limestone walls are rills, formed by dissolution by slightly acidic rainwater draining into the pond.





Purslane Pit (above & below) - this very small, ephemeral pond just west of Wild Dilly Pond is normally covered in a greenish & reddish, low-growing succulent called the sea purslane, Sesuvium portulacastrum (Plantae, Angiospermophyta, Caryophyllales, Aizoaceae).  The lake drain/conduit is a small opening in the limestone on the western edge of the depression.

Above: Purslane Pit, looking ~west.  The lake drain is the small grayish area where the person at center is pointing.

Below: lake drain for Purslane Pit.  The water is reported to be ~normal marine salinity.





Osprey Lake (a.k.a. Osprey Pond) (above & below) (looking ~SW) - this medium-sized lake is separated from Northeast Arm Lake (= part of San Salvador Island’s Great Lake System) by a narrow barrier (see below).  Osprey Lake water salinites are ~normal marine to hypersaline.  Water enters and exits via a lake drain/conduit and a tidal channel in the barrier beach.



References cited:


Godfrey, P.J., D.C. Edwards, R.R. Smith & R.L. Davis.  1994.  Natural History of Northeastern San Salvador Island: a “New World” Where the New World Began, Bahamian Field Station Trail Guide.  28 pp.



Mylroie, J.E. & J.L. Carew.  2008.  Field Guide to the Geology and Karst Geomorphology of San Salvador Island.  88 pp.



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