ABSTRACT1. While conservationists, resource managers, scientists and coastal planners have recognized the broad applicability of marine protected areas (MPAs), they are often implemented without a firm understanding of the conservation science } both ecological and socio-economic } underlying marine protection. The rush to implement MPAs has set the stage for paradoxical differences of opinions in the marine conservation community.2. The enthusiastic prescription of simplistic solutions to marine conservation problems risks polarization of interests and ultimately threatens bona fide progress in marine conservation. The blanket assignment and advocacy of empirically unsubstantiated rules of thumb in marine protection creates potentially dangerous targets for conservation science.3. Clarity of definition, systematic testing of assumptions, and adaptive application of diverse MPA management approaches are needed so that the appropriate mix of various management tools can be utilized, depending upon specific goals and conditions. Scientists have a professional and *Correspondence to: Dr T. Agardy, Sound Seas, Bethesda, MD 20816, USA. E-mail: tundiagardy@earthlink.net 1 The views expressed in this manuscript are those of the authors and do not necessarily reflect the official views or policies of their affiliated institutions. 2 Order of authorship is alphabetical by family name and does not indicate relative level of effort to the development of this paper. ethical duty to map out those paths that are most likely to lead to improved resource management and understanding of the natural world, including the human element, whether or not they are convenient, politically correct or publicly magnetic.4. The use of MPAs as a vehicle for promoting long-term conservation and sustainable use of marine biodiversity is in need of focus, and both philosophical and applied tune ups. A new paradigm arising out of integrated, multi-disciplinary science, management and education/outreach efforts must be adopted to help promote flexible, diverse and effective MPA management strategies. Given scientific uncertainties, MPAs should be designed so one can learn from their application and adjust their management strategies as needed, in the true spirit of adaptive management.5. It is critical for the conservation community to examine why honest differences of opinion regarding MPAs have emerged, and recognize that inflexible attitudes and positions are potentially dangerous. We therefore discuss several questions } heretofore taken as implicit assumptions: (a) what are MPAs, (b) what purpose do MPAs serve, (c) are no-take MPAs the only legitimate MPAs, (d) should a single closed area target be set for all MPAs, and (e) how should policymakers and conservation communities deal with scientific uncertainty?

Unattached, cellulolytic bacteria isolated from a salt marsh were cultured on [LSN]ammonium sulfate and ['Qglucose and fed to the American oyster Crassostrea virginica. Oysters were able to digest and assimilate bacterial C with an assimilation efficiency of 52.5%. We estimate that freeliving bacteria may be capable of supplying up to -9.5% of the total C requirements of oysters in their natural habitat. Cellulolytic bacteria were also cultured on 14C-labeled refractory Spartina alternlyora particles as the sole C source and [rSN]ammonium sulfate as a source of N. These labeled bacteria, together with the S. a/terniforu, were fed to the oysters. The refractory C from these detrital complexes was assimilated by the oysters with an efficiency of 10.3%. It was significantly (P = 0.0007) greater than the assimilation efficiency of 2.7% measured in a previous study for oysters feeding on the refractory S. alterniflora substrate alone. This result provides direct experimental evidence that cellulolytic bacteria in the environment can contribute to the transfer of C from refractory detritus to an ecologically important suspension-feeding macroinvertebrate.We calculated that C. virginica, when fed detrital complexes, assimilated bacterial N with an efhciency of 57.2% but that assimilation of total N present in the detrital complexes was only 3.4%. We speculate that this low assimilation efficiency was due to most (94%) of the N being in the form of condensation products such as humic geopolymers and extracellular polymeric substances secreted by bacteria which could not be digested and absorbed by the oysters. Calculations show that detrital complexes in the natural environment may provide a significant contribution to an oyster's C demand. The magnitude of this contribution can increase from 1.3 to 60% as both absolute bacterial abundance and proportion of bacteria attached to detrital particles increase, raising the oysters' efficiency of filtration for these substrates.The trophic relationship between filterfeeding bivalves and detrital complexes in the seston is poorly understood, although the potential value of the detrital complex as a food source for estuarine organisms is well recognized (Darnell 1967;Frankenberg and Smith 1967). Detrital-based food webs may add stability to ecosystems by making energy fixed seasonally in primary production available to consumers over extended periods (Riley 1963; Heinle and Flemer

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A prototype in-water laser line-scanning multispectral fluorescence imaging system was evaluated for its ability to provide data that could be used to determine the quantitative distribution and abundance of various functional groups on coral reefs. The system collected fluorescence imagery in three spectral bands with 1 cm 2 resolution at sites in Florida and the Bahamas. Fluorescence excitation was at 488 nm, and imagery was collected in emission bands centered at 520, 580, and 685 nm. Ground truth data on bottom cover was collected by divers using conventional line transect and photographic quadrat methods. A set of classification rules based on the relative signal levels in the three fluorescence channels was developed to assign the image pixels to functional groups. Once the image was classified, percent cover data for the groups were computed for the full image and for subsets of the image chosen to simulate line transect, grid survey, and photographic quadrat surveys. The statistics of percent cover of various bottom types derived from the fluorescence image compared favorably with those determined by diver survey techniques. The results demonstrate that fluorescence imaging has the long-term potential to provide coverage of large spatial areas of coral reefs at high resolution, with automated classification and quantification of functional groups in the image. AcknowledgmentsThis work was supported by grants to C.H.M., M.P.L., M.P.S., and B.C. from the Coastal Benthic Optical Properties program of the Environmental Optics Program, Office of Naval Research, and to M.P.C. from the U.S. Man and the Biosphere Program. We thank the Caribbean Marine Research Center at Lee Stocking Island, Bahamas, Florida Keys National Marine Sanctuary (FKNMS), National Oceanic and Atmospheric Administration (NOAA), Harbor Branch Oceanographic Institution, and the crews of the R/V Edwin Link, NOAA ship Ferrel, the FKNMS R/V Cool Hand, and the Florida Institute of Oceanography R/V Suncoaster for field support.