Digital Commons @ Florida Atlantic
Not a member yet
400 research outputs found
Sort by
SUBMERSIBLE STUDIES OF DEEP-WATER-OCULINA AND LOPHELIA CORAL BANKS OFF SOUTHEASTERN U.S.A.
Get PDFTwo types of deep-water coral banks occur off the coast of southeastern United States: Oculina and Lophelia/Enallopsammia. The Oculina banks form an extensive reef system at depths of 70-100 m along the shelf edge off central eastern Florida. These reefs are comprised of \u3e100 individual pinnacles and ridges which are up to 24 min height. Each pinnacle is actually a bank of unconsolidated sediment and coral debris that is capped on the slopes and crest with living colonies of Oculina varicosa. the ivory tree coral. In comparison, deep-water banks of Lophelia and Enallopsammia corals occur at depths of 490-870 m along the base of the Florida-Hatteras slope on the west side of the Florida Straits and also on the Blake Plateau off South Carolina and Georgia. The morphology and functional structure of both the Oculina and Lophelia banks are similar. This paper summarizes 10 years of submersible studies on the deep-water Oculina reefs and describes recent submersible reconnaissance of the Lophelia banks off southeastern U.S.A
EASTERN ATLANTIC EXPEDITION: SUBMERSIBLE AND SCUBA COLLECTIONS FOR BIOACTIVE ORGANISMS FROM THE AZORES TO WESTERN AFRICA.
Get PDFResearch expeditions conducted by Harbor Branch Oceanographic Institution on the R/V Sea Diver in 1990 and on the R/V Seward Johnson in 1991 explored the waters of the Azores, Madeira Islands. Salvage Islands, Canary Islands, Republic of Cape Verde, and the west African countries Senegal and Sierra Leone. The objectives were to collect marine macro- and microorganisms for the purpose of isolating novel, biologically active compounds with potential as therapeutic agents for human diseases. A total of 1,756 samples of macroinvertebrates and algae were collected at 254 sites, utilizing submersible. scuba, trawl, and dredge. During 69 operational days, 28 diver-scientists using DCIEM dive tables made 547 dives, totaling 403 hr bottom time, to depths of 40 m. Deep-water (40 - 914 m) collections with the Johnson-Sea-Link I submersible discovered rugged, steep volcanic slopes off Madeira, Salvage and Canary Islands, and also dense populations of black coral, gorgonians, and sponges. The dominant taxa consisted of Porifera (49.6%), Cnidaria (19.3%), Rhodophyta Echinodermata (8.0%), Phaeophyta (6.2%), Ascidiacea (5.9%), Chlorophyta (2.7%) and Mollusca (2.0%). Biological affinities of many of the algae, cnidarians, sponges, and ascidians from Azores, Madeira, Salvage and Canary Islands are Mediterranean and west African. In contrast, the benthic communities in the warmer water of Cape Verde, Senegal, and Sierra Leone had more tropical and Caribbean similarities. Biological activities of sample extracts were tested with cytotoxic (P388), antitumor (A549), cell adhesion (EL4), and antifungal (Candida albicans) assays. Of the 759 samples tested, approximately 10% showed bioactivity
MICROCOLINS A AND B, NEW IMMUNOSUPPRESSIVE PEPTIDES FROM THE BLUE-GREEN ALGA LYNGBA MAJUSCULA.
Get PDFMicrocolin A [1] and microcolin B [2] are new immunosuppressive lipopeptides isolated from a Venezuelan sample of the blue-green alga Lyngbya majwcnh. The microcolins are potent inhibitors of the murine mixed lymphocyte response and murine P-388 leukemia in vitro. Isolation and structure elucidation of 1 and 2 by nmr, mass spectral, and chemical methods are described.
Marine organisms have emerged as an abundant source of novel peptide secondary metabolites (1). Several of these, such as the didemnins ( 2 4 ) , dolastatins ( 5 4 , and discodermins (9-11), have been shown to possess striking biological activity, for the most part in the antiviral, antitumor, cytotoxic, and antimicrobial areas. Our ongoing interest in the isolation of marine-derived immunomodulatory agents (12-14) led us to examine a specimen of Lyngbya majuscula Gamont (Oscillatoriaceae) {=Microcoleus lyngbyaceus (Kutzing) Crouan sensu Drouet), collected in Venezuelan waters. We report here the isolation and structure determination of two novel, potent immunosuppressive lipopeptides, microcolins A [1] and B [2]. The microcolins are related in structure to majusculamide D and deoxymajusculamide D (15), the difference being substitution of an N-methylleucine residue in place of the N, 0-dimethyltyrosine in the corresponding majusculamide D compounds
BIOMEDICAL RESEARCH IN THE SEA, A SEARCH FOR DRUGS AND NOVEL COMPOUNDS.
Get PDFBiomedical research has discovered numerous pharmaceutical drugs and novel compounds produced by living organisms. Most of this research has focused on terrestrial sources but a potential reservoir of untapped drugs is being discovered in the oceans. Compounds produced from marine sponges, tunicates, bryozoans, soft corals and algae are being tested as potential agents against cancer, AIDS and other diseases. In this effort, the goal of the Division of Biomedical Marine Research (DBMR) at Harbor Branch Oceanographic Institution (HBOI) is to isolate and identify bioactive compounds from marine organisms. Since 1984 over 16,000 macroorganisms have been collected worldwide by HBOI personnel using scuba, JOHNSON-SEA-UNK submersibles and ROVs to depths of 9!5m. Biological assays of samples collected determine potential leads for antitumor, antiviral, antifungal, antibacterial and immunomodulatory agents. Active compounds are then isolated and structurally identified by nuclear magnetic resonance and mass spectroscopies. Presently over 200 chemical structures of biologically active compounds have been determined by DBMR scientists and affiliates resulting in 14 issued and allowed patents and 44 publications
USE OF PHOTOGRAMMETRIC TECHNIQUES TO MONITOR CORAL REEF RECOVERY FOLLOWING A MAJOR SHIP GROUNDING.
Get PDFPhotogrammetric techniques were used in a detailed study of benthic coral reef communities following a major physical disturbance, the grounding of the freighter Wellwood on Molasses Reef, in Key Largo National Marine Sanctuary, Florida. The sessile reef communities of the Wellwood site and the adjacent unimpacted reef areas were studied with non-destructive samplings of permanently located quadrats to document the recruitment of organisms and reef recovery in the impacted area. The grounding site was rapidly colonized by an algal community that was soon dominated by a fine algal turf composed of filamentous red algae. Although algal diversity and total algal abundance quickly returned to the levels of the nearby unimpacted reef, there remained a significant number of differences in the species composition and in the abundance of individual species. More conspicuously, the major benthic invertebrates of the community, particularly the important reef-building hard corals, recruited into the impacted area much more slowly, if at all, than the algae. By the end of the study, there was still a substantial number of major differences between the algal community of the impacted area and the unimpacted reef. The advantages of the techniques used in this study included: a minimal impact on a protected reef community, a large sample size for adequate statistical analysis, and high precision and quality-control
BIOLOGICAL AND GEOLOGICAL PROCESSES AT THE SHELF EDGE INVESTIGATED WITH SUBMERSIBLES.
Get PDFStudies of living reefs along the shelf edge off eastern Florida and the Bahamas suggest the interrelation of physical, biological, and geological processes. JOHNSON-SEA-LINK submersibles were used to sample corals and sediment with a manipulator or by lock-out diving. Videotape and 35 mm cameras, CTD system, and transmissometer were used to document the dives. Sediment traps, light meters, time-lapse camera, thermographs, and current meters were deployed and recovered. A 222 km long reef system of discontinuous pinnacles capped with living and dead Oculina coral was studied off Florida. Upwelling may contribute to growth and community structure of the reef system. Growth rates of the coral averaged 1.6 cm/yr and the coral harbors diverse faunal assemblages. Each pinnacle produces carbonate sediment and traps mud sized particles. Sand and gravel particles are not transported far from the reefs. On the margin of Little Bahama Bank sediment traps were also deployed to study sediment transport through reef notches from shallow to deep water. Average sediment flux over the edge of the wall was 1.34 kg notch-1 yr-1. Studies of living reefs along the shelf edge off eastern Florida and the Bahamas suggest the interrelation of physical, biological, and geological processes. JOHNSON-SEA-LINK submersibles were used to sample corals and sediment with a manipulator or by lock-out diving. Videotape and 35 mm cameras, CTD system, and transmissometer were used to document the dives. Sediment traps, light meters, time-lapse camera, thermographs, and current meters were deployed and recovered. A 222 km long reef system of discontinuous pinnacles capped with living and dead Oculina coral was studied off Florida. Upwelling may contribute to growth and community structure of the reef system. Growth rates of the coral averaged 1.6 cm/yr and the coral harbors diverse faunal assemblages. Each pinnacle produces carbonate sediment and traps mud sized particles. Sand and gravel particles are not transported far from the reefs. On the margin of Little Bahama Bank sediment traps were also deployed to study sediment transport through reef notches from shallow to deep water. Average sediment flux over the edge of the wall was 1.34 kg notch-1 yr-1
EFFECTS OF NATURAL AND ARTIFICIAL THALASSIA ON RATES OF SEDIMENTATION.
Get PDFSediment traps were used to measure the rate of deposition in a Thalassia seagrass meadow and in an adjacent (sandy) grass-free area. The average depositional rate of mud in the Thalassia bed was 4.96 g trapˉ¹ weekˉ¹, and in the sandy area, it was 3.04 g trapˉ¹ weekˉ¹ in the summer. In winter, these rates were 1.60 and 1.50 g mud trapˉ¹ week ˉ¹, respectively. Electromagnetic current-meter measurements showed that the mean flow velocity in the grass-free area is higher than in the seagrass area. Therefore, the increased depositional rate of mud within the seagrass is due to slowing of water currents by the grass blades. Confirmation of the blade baffle effect was obtained by placing a 1-m² plot of artificial Thalassia in a grass-free area. Sediment traps in the artificial Thalassia contained 5.45 g mud trapˉ¹ weekˉ¹ as compared to 3.04 g mud trapˉ¹ weekˉ¹ in the adjacent grassfree area in summer. In winter, these rates were 1.82 and 1.50 g mud trapˉ¹ weekˉ¹, respectively. Epiphytes in the Indian River Lagoon had no detectable effect on the amount of mud deposited in Thalassia beds
SEDIMENTS FROM A LIVING SHELF-EDGE REEF AND ADJACENT AREA OFF CENTRAL EASTERN FLORIDA.
Get PDFJeff\u27s Reef (270 32.5\u27 N; 790 58.3\u27 W), a 16m high Oculina coral bank on the shelf-slope break, is the site of modem carbonate sedimentation mixed with relict carbonate and quartz. Surficial sediments from the 94 km2 surrounding area of outer shelf, shelf edge and upper slope are significantly different from reef sediments as judged by wt.% gravel, sand, silt, clay, mud, sorting, skewness and normalized kurtosis. Sand grain types (ooid +pellet+ carbonate rock fragments, barnacles and coral) are also different for reef and non-reef areas. Sediments of non-reef origin in the adjacent areas have significantly larger between-station variance than within-station variance for the above grain size descriptors. These sediments have significant changes in grain size descriptors E-W, and no significant changes N-S.
Sediment on the eastern shelf (48m depth) is unimodal coarse-skewed sand; shelf-edge sediment (80m depth) is bimodal, coarse-skewed sand; and upper slope sediment (140m depth) is unimodal, fine-skewed sand. Gravel fractions of non-reef sediments are dominated by shells and shell hash. By volume, sand fractions are composed of detrital silicate 25.7%, ooids 9.4, pellets 1 0.6, carbonate rock fragments 4.5, molluscs 23.0, barnacles 2.2, forams 10.6, coralline algae 0.3, coral 0.2, echinoderms 2.2, and unknowns 11 .0. Jeff\u27s Reef sediments (70-80m depth) are polymodat gravelly sands with the gravel fractions composed mainly of broken Oculina branches (up to 70% by wt.). By volume, sand fractions are composed of detrital silicate 26.8%, ooids 4.3, pellets 6.7, carbonate rock fragments 3.8, molluscs 23.6, barnacles 7 .3, forams 12.2, coralline algae 0.2, coral 1.1, echinoderms 3.3, and unknowns 1 0.0. Reef top sands contain significantly more coral and barnacles, and significantly less molluscs and carbonate rock fragments than the reef base.
Sediment originated from the reef contains more mud (X = 14.3%) than nearby shelf sediments at the same depth (X= 4.6%). Coral branch gravel is not transported from the reef but export of coral sand is detectable. Current velocities near the reef base exceed 15 cm sec-1 17% of the time in winter and 11% of the time in summer. A 2 km wide band of shell hash between 70-100 m is elongated N-S suggesting transport parallel to the coast
THE MOLLUSCAN COMMUNITY ASSOCIATED WITH THE SCLERACTINIAN CORAL OCULINA VARICOSA.
Get PDFThe molluscan community associated with the scleractinian coral Oculina varicosa is compared among four reef sites: inner shelf (6 m), midshelf (27 m), outer shelf (42 m), and shelf edge (80 m). Enumeration ofall the mollusks from 41 coral samples yielded 5,132 individuals and 230 species-level taxa, including 155 gastropods, 68 bivalves, I scaphopod, 5 polyplacophorans, and I cephalopod. Of these taxa, approximately 47% were free living (motile), 32% symbiotic (parasitic or commensal), 18% epilithic (fouling), and 3% endolithic (boring). The species assemblage at the 80-m reef was very distinct from that at 6 m. Approximately 75% of the individuals collected at 6 m were herbivores or detritivores; higher light levels and sedimentation from wave surge at this station may account for this dominance. Carnivores dominated at the 80-m station (62.1% ofthe individuals) but were uncommon at 6 m (4.8%). At the 80-m station, greater coral coverage permitted more coral-eating mollusks, and greater percentage of dead coral per colony enabled more epilithic species and associated symbionts to exist. The corallum of O. varicosa was denser at 80 m and the branches were generally thinner than at 6 m, possibly accounting for the fewer numbers and species ofboring mollusks at the 80-m reef. Periodic coldwater upwelling and cooler average temperatures may account for the greater numbers of eurythermic tropical, temperate, and boreal species at the 80-m reef than at the 6-m reef
PRODUCTION AND OFF-BANK TRANSPORT OF CARBONATE SEDIMENT, BLACK ROCK, SOUTHWEST LITTLE BAHAMA BANK.
Get PDFSurficial sediments between the intertidal zone and 600 m were studied with the objectives of characterizing their source, dispersal pathways and sites of accumulation. Bioerosion is a major source of sediment in the intertidal and shallow subtidal environments. In-situ enclosure experiments showed that the urchin Echinometra lucunter produced 667 mg sediment cm -2 yr-1, and an associated diverse rock infauna produced an additional 183mg cm-2 yr-1. Microborers caused erosion of 25 mg cm -2 yr -1, and feeding activity by the chiton Acanthopleura granulate caused additional erosion of 10 mg cm-2 yr-1. Sequential weighing of tethered limestone plates showed an abrasion rate of 5.5 mg cm-2 yr-1 due chiefly to impacts on the plate edges.
Surficial sediments between the intertidal zone and the top of the bank-margin wall at 30 mare gravel-sand mixtures containing 0-2% mud. Molluscs and Halimeda plates are the main constituents of gravel fractions. Sand fractions are composed of bioerosion-produced carbonate rock fragments (1-70%), skeletal material from Halimeda (3-63%), forams (1-33%), molluscs (6-15%) and coral (0-6%).
Gravel and sand are transported as bedload in chutes across the narrow, rocky shelf. Chutes end at 45 m, and sediment traps indicate an average flux of 5.4 kg chute -1 yr-1, equivalent to 945 kg km -1 yr-1, moving to deep water. A dense population of Halimeda living on the wall, between 30-70 m, contributes gravel and sand to sediment on wall ledges. At the base of the steep wall (65°), a ramp slopes into the Northwest Providence Channel. Between 120-300 m, the ramp (300 slope) is a zone by-passed by coarse and fine sediment.
At 300 m, the slope decreases to an average of 13°, and an apron-shaped body of mud is accumulating. The apron extends parallel to the bank margin and wall, and reaches depths\u3e 600 m. Traps showed that sediment flux to the ramp is 0.12 kg m -2 yr -1, which is 2% of the particle flux overtopping the bank margin. Surficial sediment of the ramp is mostly mud (\u3e 70%) which is primarily of shallow-water origin. Some form of bottom current transporting gravel and sand (mostly Halimeda and abraded coral heads) has cut gullies into the ramp. This bottom flow is probably episodic, and turbulent enough to suspend and supply Halimeda sand to sediment traps on the ramp at 463 m