V.
Field Survey at Isla Desecheo
1. Description of Study Area
Desecheo is an oceanic island located in Mona Passage, about 12 nautical miles off
Rincon, northwest coast of Puerto Rico. The emergent section of the island is about 1.6
km long by 1.4 km wide. Its submerged insular shelf, down to a depth of 100 m along its
most extensive northeast to southwest axis is approximately 5 km long. Surrounding
depths range between 400-900 m, increasing abruptly to the north, where the
southwestern edge of the Puertorrican Trench is found (Figure 9). The island,
designated as a Natural Reserve in 1999, was used as a shooting range by the U. S.
Navy during the Second World War.
Marine communities at Isla Desecheo are influenced by exceptionally clear waters, swift
currents and seasonally strong wave action associated with North Atlantic winter swells.
A rocky shoreline fringes the entire island, except for two small beach coves on the west
and southwest coast (Puerto Botes and Puerto Canoas). A federally and locally
enforced closure to fishing practices is in effect year-round. The protected area includes
a fringe of 0.5 miles around the island.
The northwest shelf of Isla Desecheo consists of a series of massive lava rock
promontories partially displaced from the main island. Hard substrate is mostly
colonized by a dense algal turf with encrusting brown macroalgae. Scleractinian corals
cover approximately 25.2 % of the substrate at a depth of 10.6 m on the North Reef of
Isla Desecheo (García et al., 2001b). Due north, an isolated rock promontory known as
the “Yellow Reef” rises from a depth of 38 m at its base to a pinnacle at approximately 6
m from the surface. This reef is extensively colonized by benthic algae (mostly
encrusting fan-leaf alga, Lobophora variegata), colonial hydrozoans, hydrocorals and
encrusting sponges and corals. To the northeast, the shelf is relatively wide and
gradually slopes down along a flat, hard and mostly un-colonized bottom with sand
channels and scattered small rock promontories encrusted by benthic algae, corals and
sponges. The east coast features a narrow shelf with an abrupt slope. Rock
promontories surge from narrow terraces down the slope at depths ranging from 30 to
50 meters. These rock reefs are relatively small (less than 30 m long) and are mostly
covered by encrusting algae, sponges and isolated corals.
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Field Survey at Isla Desecheo
1. Description of Study Area
Desecheo is an oceanic island located in Mona Passage, about 12 nautical miles off
Rincon, northwest coast of Puerto Rico. The emergent section of the island is about 1.6
km long by 1.4 km wide. Its submerged insular shelf, down to a depth of 100 m along its
most extensive northeast to southwest axis is approximately 5 km long. Surrounding
depths range between 400-900 m, increasing abruptly to the north, where the
southwestern edge of the Puertorrican Trench is found (Figure 9). The island,
designated as a Natural Reserve in 1999, was used as a shooting range by the U. S.
Navy during the Second World War.
Marine communities at Isla Desecheo are influenced by exceptionally clear waters, swift
currents and seasonally strong wave action associated with North Atlantic winter swells.
A rocky shoreline fringes the entire island, except for two small beach coves on the west
and southwest coast (Puerto Botes and Puerto Canoas). A federally and locally
enforced closure to fishing practices is in effect year-round. The protected area includes
a fringe of 0.5 miles around the island.
The northwest shelf of Isla Desecheo consists of a series of massive lava rock
promontories partially displaced from the main island. Hard substrate is mostly
colonized by a dense algal turf with encrusting brown macroalgae. Scleractinian corals
cover approximately 25.2 % of the substrate at a depth of 10.6 m on the North Reef of
Isla Desecheo (García et al., 2001b). Due north, an isolated rock promontory known as
the “Yellow Reef” rises from a depth of 38 m at its base to a pinnacle at approximately 6
m from the surface. This reef is extensively colonized by benthic algae (mostly
encrusting fan-leaf alga, Lobophora variegata), colonial hydrozoans, hydrocorals and
encrusting sponges and corals. To the northeast, the shelf is relatively wide and
gradually slopes down along a flat, hard and mostly un-colonized bottom with sand
channels and scattered small rock promontories encrusted by benthic algae, corals and
sponges. The east coast features a narrow shelf with an abrupt slope. Rock
promontories surge from narrow terraces down the slope at depths ranging from 30 to
50 meters. These rock reefs are relatively small (less than 30 m long) and are mostly
covered by encrusting algae, sponges and isolated corals.
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