Inventory and Atlas of Corals and Coral Reefs, with Emphasis on Deep-Water Coral Reefs from the U
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Inventory and Atlas of Corals and Coral Reefs, with Emphasis on Deep-Water Coral Reefs from the U. S. Caribbean EEZ Jorge R. García Sais SEDAR26-RD-02 FINAL REPORT Inventory and Atlas of Corals and Coral Reefs, with Emphasis on Deep-Water Coral Reefs from the U. S. Caribbean EEZ Submitted to the: Caribbean Fishery Management Council San Juan, Puerto Rico By: Dr. Jorge R. García Sais dba Reef Surveys P. O. Box 3015;Lajas, P. R. 00667 [email protected] December, 2005 i Table of Contents Page I. Executive Summary 1 II. Introduction 4 III. Study Objectives 7 IV. Methods 8 A. Recuperation of Historical Data 8 B. Atlas map of deep reefs of PR and the USVI 11 C. Field Study at Isla Desecheo, PR 12 1. Sessile-Benthic Communities 12 2. Fishes and Motile Megabenthic Invertebrates 13 3. Statistical Analyses 15 V. Results and Discussion 15 A. Literature Review 15 1. Historical Overview 15 2. Recent Investigations 22 B. Geographical Distribution and Physical Characteristics 36 of Deep Reef Systems of Puerto Rico and the U. S. Virgin Islands C. Taxonomic Characterization of Sessile-Benthic 49 Communities Associated With Deep Sea Habitats of Puerto Rico and the U. S. Virgin Islands 1. Benthic Algae 49 2. Sponges (Phylum Porifera) 53 3. Corals (Phylum Cnidaria: Scleractinia 57 and Antipatharia) 4. Gorgonians (Sub-Class Octocorallia 65 D. Taxonomic Characterization of Sessile-Benthic Communities 68 Associated with Deep Sea Habitats of Puerto Rico and the U. S. Virgin Islands 1. Echinoderms 68 2. Decapod Crustaceans 72 3. Mollusks 78 E. Fishes Associated with Deep Sea Habitats of Puerto Rico 79 and the U. S. Virgin Islands 1. Early Collections and Records 79 2. Deep Sea Larval Fish Studies 84 ii 3. Commercial Deep Sea Fisheries 85 4. Seward-Johnson Submersible Survey 88 F. Field Survey at Isla Desecheo, Puerto Rico 99 1. Description of Study Area 99 2. Biological Characterization of Marine Communities 105 2.1 Sessile-Benthic communities 105 2.1.1 SW Wall Reef – 30 m 105 2.1.2 SW Wall Reef – 40 m 111 2.1.3 Agelas Reef – 50 m 116 2.2 Fishes 124 2.2.1 Fishes – 30 m 124 2.2.2 Fishes – 40 m 134 2.2.3 Fishes – 50 m 143 VI. Conclusions 151 VII. Literature Cited 153 VIII. Appendices 164 1. Taxonomic Record of Ahermatypic Corals Reported 165 for the Caribbean Sea 2. Taxonomic Record of Fishes Reported for PR and the USVI 167 3. Catch record of stations sampled during the NMFS-NOAA 207 fishery survey 4. Taxonomic composition and abundance of fishes associated 209 with the drop-off wall reef at a depth of 30 meters 5. Taxonomic composition and abundance of fishes associated 212 with the drop-off wall reef at a depth of 40 meters iii 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 and grouper fisheries potential were performed during the late 70’s and throughout the 1980’s by the National Marine Fishery Service in collaboration with the local governments of Puerto Rico, USVI, and the Caribbean Fishery Management Council. These surveys consisted of at least 11 cruises of the R/V Oregon II, R/V Delaware II and the Seward Johnson-Sea Link II submersible survey of the insular slope of PR and the USVI in 1985. The submersible survey provided an unprecedented and exceptional insight of our deep sea reef communities at depths between 100 – 1250 meters. Despite the generalized conclusion from these surveys that deep sea fish stocks were depauperate, deep sea snapper and grouper fisheries still represent the main fisheries resource in terms of catch and value in the U. S. Caribbean EEZ. The first quantitative assessment of reef substrate cover by benthic communities from deep hermatypic reefs of the upper insular slope of PR was produced by Singh et al. (2004) using the SeaBED Autonomous Underwater Vehicle (AUV) off the La Parguera shelf-edge. The SeaBED AUV is an imaging platform designed for high resolution optical and acoustic sensing. Scleractinian corals were the dominant sessile-benthic invertebrate at depths down to 30 m, with maximum reef substrate cover (25 %) at the 24 – 30 m depth interval. Below 30 m, sponges were the dominant sessile-benthic invertebrate with a mean substrate cover of less than 10%. Benthic algae, sand and other abiotic substrates prevailed down the insular slope of La Parguera to a maximum depth of 125 m. Black corals (Antipathes sp. and Cirrhipathes sp.) were reported from the deepest section of the transect (90-100 m). The SeaBED AUV imaging platform was used in June 2003 to survey the Hind Bank (MCD) benthic habitats south of St. Thomas, USVI, at depths between 32 to 54 m. Within the western side of the MCD, a well-developed deep hermatypic coral reef with 43 % mean living coral was found. The flattened growth form of boulder star coral, Montastrea annulari- franksi was the dominant taxonomic component of the sessile-benthos at all four sites surveyed in the MCD. Maximum coral cover found was 70 % at depths of 38 - 40 m. A similar deep hermatypic reef system, known as Black Jack Reef was studied off the south coast of Vieques, PR. The seamount rises from a depth of 51 m to a reef top at 30 m. A total of 25 species of scleractinian corals, two antipatharians and one hydrocoral were identified. Live coral cover averaged 28.8 % (range 25.0 – 40.4 %) within video-transect areas. Boulder star coral (Montastrea annularis - franski) was the dominant coral species in terms of substrate cover (mean: 21.9 %), representing 76 % of the total live coral cover at depths between 36 – 40 meters. Boulder star coral exhibited laminar, or flattened growth with closely spaced colonies of moderate size and low relief. Corals grow from a pedestal of unknown origin, creating a large protective habitat underneath the coral. 2 Deep hermatypic reefs have also been discovered at the southwest coast of Isla Desecheo. These include the SW Wall Reef, at depths between 30-40 m, and Agelas Reef, at depths between 45 – 70 m. Substrate cover at the SW Wall Reef was dominated by benthic macroalgae (mostly Lobophora variegata), sand, sponges, and massive corals. Sponges were highly prominent (mean surface cover: 17.3 %), growing mostly as large erect and branching forms that produced substantial topographic relief and protective habitat for fishes and invertebrates. In many instances, sponges were observed growing attached to stony corals, forming sponge-coral bioherms of considerable size. One of the most common associations involved the brown tube (Agelas conifera, A. sceptrum) and row pore sponges (Aplysina spp.) with star corals (Montastrea cavernosa, M. annularis). A total of 25 scleractinian corals, three hydrocorals and two antipatharian (black coral) species were present along the SW Wall Reef.