385 research outputs found

    Growth Characteristics of Reef-Building Corals Within and External to a Naval Ordinance Range: Vieques, Puerto Rico

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    The skeletal growth of reef·building corals is known to be sensitive to the environment. In particular, high levels of sedimentation and turbidity lead to decreased growth rate, suppressed growth variation, and, ultimately, coral death because of reduced illumination necessary to zooxanthellae and/or increased energy expenditure by the coral animal to remove impacted sediments. To assess the effect of Naval Ordnance Range usage at Vieques, Puerto Rico, specimens of Montastrea annulariswere collected from reefs adjacent to and removed from the range area. Growth was measured from annual increments revealed by X-radiography of medial slabs of the coral skeletons. Mean growth rates and growth variances were calculated for each station or station grouping over the common time period 1970-1977. Statistical comparison of the growth data reveals a general similarity between range and control stations. This evidence coupled with quantitative coral abundance and diversity data of others indicate a lack of anomalous and adverse sedimentation/turbidity conditions affecting corals on reefs near the range area. Chronologies of coral band widths compared to historical recorded environmental data indicate that a major natural parameter which controls coral growth in Vieques is annual water temperature variation

    X-Rays Provide Researchers with Views of Coral Growth Patterns

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    Effects of Drilling Mud on the Reef-Building Coral Montastrea annularis

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    The skeletal extension and corallite shape of individuals of the Caribbean and Atlantic reef-building coral Montastrea annularis (Ellis and Solander) were measured after more than six weeks\u27 continuous flow-through exposure in laboratory aquaria to treatments of 0, 1, 10 and 100-ppm (μl 1-1) drilling mud. Linear increase of the skeleton (extension rate) and fossa length were significantly depressed in the 100-ppm treatment. Chronic exposure to 100-ppm drilling mud impairs coral skeletal growth rate and possibly interferes with sediment rejection capability by lowering calical relief

    Coral populations and growth patterns: Responses to sedimentation and turbidity associated with dredging

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    Analysis of coral growth patterns and populations in Bermuda reveals that living coral abundance on the reefs of Castle Harbor, a location where extensive dredging occurred during 1941- 1943, is much reduced in comparison to external North-South reefs. Dead corals, sampled in the harbor, have skeletal patterns of growth which are similar and which show a marked decline in growth for several years prior to death...

    Annual Periodicity of the 18O16O and 13C12C ratios in the coral Montastrea annularis

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    The isotopic ratios 18O/16O and 13C/12C show an annual periodicity in the coral Montastrea annularis from Bermuda, Jamaica and Barbados. The abundances of 18O and 13C are positively correlated in the Jamaica and Barbados samples, but inversely related in the Bermuda sample. Annual high density growth bands are formed during the season of warmest water temperature at all 3 sites and are enriched in 16O. M. Annularis has a constant displacement from oxygen isotopic equilibrium and accurately records seasonal temperature variations via the temperature-dependent aragonite-water fractionation factor. Light intensity, through the activity of the coral\u27s endosymbiotic algae, regulates the depth-dependent and seasonal variations in the skeletal carbon isotopic composition

    Visual_HEA: Habitat Equivalency Analysis Software to Calculate Compensatory Restoration Following Natural Resource Injury

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    Habitat Equivalency Analysis (HEA) is a means to determine the amount of compensatory restoration required to provide services that are equivalent to the interim loss of natural resource services following an injury. HEA includes a discounting procedure to account for asset valuation in that the total asset value is equal to the discounted value of the future stream of all services from the natural resource or the compensatory resource. Discounting is used to include the relative valuation of loss and gain of ecological services of the resources over time. Visual_HEA is a computer program developed to calculate the amount of compensatory resource services that would be required to match those lost following an injury to natural resources. The program accepts input of parameters necessary to determine long-term service loss from the injury and long-term service gain from the desired compensatory restoration action. HEA results are highly dependent upon assumptions, and consequently it is useful to examine sensitivity of results to a range of parameter values. Visual_HEA offers an intuitive graphical interface that allows the user to input or modify input parameters and hence quickly create or alter the lost and gain service level shape functions. The ability to calculate results of many scenarios allows ready comparisons that may assist in determination of the most appropriate compensatory action

    Keynote Speech

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    Port Everglades Macroinvertebrate Monitoring: Monitoring of Benthic Macroinvertebrate Assemblages at the Southport Turning Basin and Adjacent Areas of John U. Lloyd State Recreation Area: August 1992 (With a Summary of the August 1991 and January 1992 Surveys)

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    This report documents the August 1992 monitoring of benthic macroinvertebrate assemblages in the Pon Everglades Southpon turning basin vicinity and adjacent areas of John U. Lloyd State Recreation Area. This is the third monitoring effort of the series carried out by Nova University Oceanographic Center. Sampling was carried out chiefly during the first two weeks of August 1992. Hurricane Andrew and its aftermath resulted in delays in sampling at several sites and in analyzing data. A two-week postponement in submission deadline was requested and granted. An additional postponement, to 31 January 1992, was requested due to a move at the Smithsonian Institution that prevented some consultants from returning identifications on time. A history of the monitoring project since its inception in 1988 was given in the report submitted December 1991 and is included here again for reference. This report also includes the tabular data for the two previous surveys (August 1991 and January 1992) together with a discussion of all three surveys carried out by Nova University. Please note modifications to the Ponar grab sample data for the January 1992 survey. In the original report for that survey, we inadvertently omitted doubling the dataset from large volume samples of which we sorted 50% (following the methodology described below). Diversity indices were not affected

    Climate Records in Coral Skeletons

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    Animal-Sediment Relations in a Tropical Lagoon: Discovery Bay, Jamaica

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    The distribution of many macrobenthic species in the back-reef lagoon of Discovery Bay, Jamaica can be related to a gradient in bottom stability. This gradient is defined by increasing rates of biogenic reworking and sediment resuspension in the western part of the lagoon. Infaunal diversity and coral growth decrease in the western, unstable areas. The infauna of the carbonate sand consists mainly of deposit feeders. In the western lagoon, the feeding activities of this group result in high biogenic reworking rates (up to 6-7 cm/week) producing loose surface sediment easily resuspended by waves. A maximum, mean resuspension rate of 19 mg/cm2/day was measured. Instability of the lagoon floor, resulting in high water turbidity, inhibits settlement and growth of most suspension feeders and reduces infaunal diversity and coral growth. Because stability of the soft-bottom is significantly influenced by deposit feeders, our observations represent an extension of the trophic group amensalism principle to tropical nearshore enviornments
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