I.
Executive Summary
Hermatypic coral reefs in deep terraces of the outer shelf, rocky outcrops and vertical wall
features of the insular slope, submerged volcanic ridges and oceanic seamounts comprise
the deep reef systems of Puerto Rico and the U. S. Virgin Islands (US Caribbean EEZ).
Ahermatypic coral banks have not been reported, but at least 33 species of azooxanthellate
(aposymbiotic) corals, including the deep water reef builder, Lophelia pertusa have been
collected from deep reef habitats of the US Caribbean EEZ. The bathymetry of the northern
and southern slope of PR and the USVI is characterized by an abrupt, almost vertical drop,
without any large topographic features (platforms) where extensive deep (ahermatypic) reef
banks could develop. There are two prominent ridge systems submerged along the west
and southeast coasts that offer the best possibilities for existence of deep coral reefs. The
most extensive is the great southern Puerto Rico fault zone, a submerged section of the
Antillean ridge that extends across the entire Mona Passage, connecting Puerto Rico with
La Hispaniola. On the southeast coast of Puerto Rico, the submerged seamounts, Bajo
Investigador, Bajo Grappler and Bajo Whitting are the most prominent deep reef systems.
These are seamount pinnacles of a submerged ridge that extends east, connecting the shelf
platform of Puerto Rico with the Island of St. Croix, USVI. The ridge is separated from the
mainland by oceanic depths of more than 1,000 meters. Bajo Grappler is the largest and
taller of the seamounts, with its pinnacle reaching less than 60 meters from the surface. As
with the west coast deep reef systems, the submerged seamounts of the south coast were
sites of an intensive fishing effort for deep water snappers and groupers during the last three
decades.
Most of the information regarding deep water habitats and associated communities in Puerto
Rico and the U. S. Virgin Islands was produced more than 100 years ago, during the early
ocean exploration surveys that included the Voyage of H. M. S. Challenger during 1873,
dredging surveys by “Blake” during 1878-79, U. S. Fish Commission “Fish Hawk” in 1899,
and the Johnson-Smithsonian Expedition aboard the Yacht Caroline in 1933. Extensive
deep sea samplings of the southwestern Atlantic were performed during the period between
1950’s through and 1970’s by the exploratory fishing vessels R/V Oregon, R/V Silver Bay,
R/V Combat, R/V Pelican, R/V Gerda, R/V Columbus-Iselin, and R/V John Elliot Pillsbury,
but most of the survey effort was concentrated in the Florida Straits, Gulf of Mexico, western
and southwestern Caribbean, Bahamas, and the Lesser Antilles. The US Caribbean EEZ
received a relatively minor attention with respect to the sampling of deep sea habitats. After
the 1970’s, most of the research attention on deep sea communities of Puerto Rico and the
USVI was focused toward fishery resources. Assessment surveys of the deep sea snapper
1
Executive Summary
Hermatypic coral reefs in deep terraces of the outer shelf, rocky outcrops and vertical wall
features of the insular slope, submerged volcanic ridges and oceanic seamounts comprise
the deep reef systems of Puerto Rico and the U. S. Virgin Islands (US Caribbean EEZ).
Ahermatypic coral banks have not been reported, but at least 33 species of azooxanthellate
(aposymbiotic) corals, including the deep water reef builder, Lophelia pertusa have been
collected from deep reef habitats of the US Caribbean EEZ. The bathymetry of the northern
and southern slope of PR and the USVI is characterized by an abrupt, almost vertical drop,
without any large topographic features (platforms) where extensive deep (ahermatypic) reef
banks could develop. There are two prominent ridge systems submerged along the west
and southeast coasts that offer the best possibilities for existence of deep coral reefs. The
most extensive is the great southern Puerto Rico fault zone, a submerged section of the
Antillean ridge that extends across the entire Mona Passage, connecting Puerto Rico with
La Hispaniola. On the southeast coast of Puerto Rico, the submerged seamounts, Bajo
Investigador, Bajo Grappler and Bajo Whitting are the most prominent deep reef systems.
These are seamount pinnacles of a submerged ridge that extends east, connecting the shelf
platform of Puerto Rico with the Island of St. Croix, USVI. The ridge is separated from the
mainland by oceanic depths of more than 1,000 meters. Bajo Grappler is the largest and
taller of the seamounts, with its pinnacle reaching less than 60 meters from the surface. As
with the west coast deep reef systems, the submerged seamounts of the south coast were
sites of an intensive fishing effort for deep water snappers and groupers during the last three
decades.
Most of the information regarding deep water habitats and associated communities in Puerto
Rico and the U. S. Virgin Islands was produced more than 100 years ago, during the early
ocean exploration surveys that included the Voyage of H. M. S. Challenger during 1873,
dredging surveys by “Blake” during 1878-79, U. S. Fish Commission “Fish Hawk” in 1899,
and the Johnson-Smithsonian Expedition aboard the Yacht Caroline in 1933. Extensive
deep sea samplings of the southwestern Atlantic were performed during the period between
1950’s through and 1970’s by the exploratory fishing vessels R/V Oregon, R/V Silver Bay,
R/V Combat, R/V Pelican, R/V Gerda, R/V Columbus-Iselin, and R/V John Elliot Pillsbury,
but most of the survey effort was concentrated in the Florida Straits, Gulf of Mexico, western
and southwestern Caribbean, Bahamas, and the Lesser Antilles. The US Caribbean EEZ
received a relatively minor attention with respect to the sampling of deep sea habitats. After
the 1970’s, most of the research attention on deep sea communities of Puerto Rico and the
USVI was focused toward fishery resources. Assessment surveys of the deep sea snapper
1