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Namuka Reef is a broad fringing reef flat situated immediately adjacent to the populous and heavily industrialized areas surrounding Suva Harbor, Fiji Islands. Reef flat sediments are mainly very poorly to moderately sorted carbonate gravels and sands with occasional boulders and very little silt' with terrigenous sediments limited to a narrow' nearshore strip. Bulk sediment geochemical analyses show that trace metal concentrations are generally very low across the reef flat and closely similar to pristine reef areas offshore rather than to the nearby contaminated areas within Suva Lagoon. Exceptions occur close to villages, however, where sediments are enriched in Pb, As, and other trace metals, and possibly near wreck sites on the reef where Fe increases locally. These data together with those for major and minor oxides show that there is little or no movement of sediments from the rivers and deeper lagoon onto the carbonate reef flat even though extreme events such as tsunamis or cyclones affect the area. This indicates that the geomorphic separation of reef flats from adjacent contaminated environments is sufficient to prevent the introduction of solid contaminants. Reef flats may thus retain healthy ecosystems and provide resources to the community even though close to heavily contaminated areas., Many coastal areas around the world have been increasingly impacted during the past century by anthropogenic contaminants that affect both water quality and the health of marine ecosystems (e.g., Wade [...]

Dense aggregations of tube-worms can stabilize sediments and generate oases for benthic communities that are different and often more diverse and abundant than those of the surroundings. If these features are to qualify as biogenic reefs under nature-conservation legislation such as the EC Habitats Directive, a level of stability and longevity is desirable aside from physical and biological attributes. Lanice conchilega (Pallas, 1766) is widely distributed around the European coast and aggregations of this tube-dwelling polychaete are known to have a positive effect on the biodiversity of associated species in inter- and sub-tidal areas. This increases the value of L. conchilega-rich habitats for higher trophic levels such as birds and fish. However, L. conchilega is currently not recognized as a reef builder primarily due to uncertainty about the stability of their aggregations. We carried out three studies on different spatial and temporal scales to explore a number of properties relating to stability: (1) Individual aggregations of L. conchilega of ~1 [m.sup.2] were monitored for up to 1 year, (2) records of L. conchilega from a 258-ha area over a 35-year period were analyzed, (3) the recovery of a population of L. conchilega subjected to disturbances by cultivation of Manila clams (Ruditapes philippinarum) was followed over 3 years. The studies provided evidence about the longevity of L. conchilega aggregations, their resistance to disturbance, their resilience in recovering from negative impact and their large-scale persistence. The results showed that populations of L. conchilega were prone to considerable fluctuation and the stability of aggregations depended on environmental factors and on recruitment. The tube-worms proved to be susceptible to disturbance by cultivation of Manila clams but demonstrated the potential to recover from that impact. The long-term monitoring of a large L. conchilega population in the Bay of Mont Saint Michel (France) indicated that aggregations can persist over many decades with a constant, densely populated core area and an expanding and contracting more thinly populated fringe zone. The stability of aggregations of L. conchilega and the structures they form do not unequivocally fit the currently accepted definition of a reef. However, given L. conchilega's accepted reef-like potential to influence diversity and abundance in benthic communities, we suggest clarifying and expanding the definition of reefs so that species with records of significant persistence in particular areas and which otherwise meet expectations of reefs are included within the definition. doi: 10.1093/icb/icq060

The Nemakit-Daldynian--Tommotian (ND-T) boundary marks the first appearance of metazoan reefs and calcite biomineralizers and is associated with the largest [delta][sup.13]C shift during the Phanerozoic Eon. Biological transitions in Earth history are often accompanied by excursions in the carbon isotopic composition ([delta][sup.13]C) of the ocean, where [delta][sup.13]C variability is interpreted to reflect changes in the global carbon cycle. The duration and thus rate of these [delta][sup.13]C anomalies are rarely known, making it difficult to constrain their possible causes and their relationship, if any, to biologic transitions. We report sedimentological and [delta][sup.13]C data from a new 2.5-km-thick section that spans the early Cambrian evolutionary 'explosion' in the Moroccan Anti-Atlas Mountains. Three new zircon [sup.206]Pb-[sup.238]U ages from tufts within the stratigraphy constrain the timing of the ND-T boundary to 524.84 [+ or -] 0.09 Ma. Two of the tufts exactly bracket the ND-T transition and constrain the duration of the -8[per thousand] [delta][sup.13]C shift to 506 [+ or -] 126 k.y. With a simple box model, we explore a range of geochemical processes that could account for such a rapid ND-T [delta][sup.13]C shift, and conclude that metamorphic and/or volcanic fluxes of carbon may have been sustained at levels 4-16 times higher than today for millions of years. doi: 10.1130/G30726.1

Storms and associated surges are major coast-shaping processes. Nevertheless, no typical sequences for storm surge deposits in different coastal settings have been established. This study interprets a coarse-grained hurricane ridge deposit on the island of Bonaire, Netherlands Antilles. The sequence was deposited during Hurricane Lenny in November 1999. Insight is gained into the hydrodynamics of surge flow by interpreting textural trends, particle imbrication, and deposit geometry. Vertical textural variations, caused by time-dependent hydrodynamic changes, were used to subdivide the deposit into depositional units that correspond to different stages of the surge, such as setup, peak, and return flow. Particle size and imbrication trends and geometry of the units reflect landward bed-load transport of components during the setup, a nondirectional flow with sediment falling out of suspension during the peak, and a seaward bed-load transport during the return flow. Formation of a ridge during setup affected the texture of the return flow unit. Changing angles of imbrication reflect alternating flow velocities during each phase. Normal grading during setup and inverse grading during return flow are caused by decelerating and accelerating flow, respectively. Hence, the interpreted deposit seems to represent the first described complete hurricane surge sequence from a carbonate environment.

Radiometrically calibrated ages from three reef cores are used to develop a Holocene reef growth chronostratigraphy and sea-level history in the Maldives, central Indian Ocean. Last interglacial reef (U-series age 122 [+ or -] 7 ka) was encountered at 14.1 m below mean sea level. An age of ca. 8100 calibrated (cal) yr B.P. immediately overlying this Pleistocene surface records the initiation of Holocene reef growth. Massive in situ corals occur throughout the cores and the consistency of the three age-depth plots indicate that the reef grew steadily between 8100 and 6500 cal yr B.P., and at a decreasing rate for the next 2 k.y. The position of modern sea level was first achieved ca. 4500 cal yr B.P. and sea level reached at least 0.50 [+ or -] 1 m higher from 4000 to 2100 cal yr B.P. before falling to present level. Emergent fossil microatolls provide evidence of this higher sea level. Results are significant to two long-standing issues relating to Maldivian sealevel history. First, the ambiguity of a late Holocene highstand has been resolved with clear evidence of its existence reported here. Second, the uncertainty of the regional pattern of sea-level change in the central Indian Ocean has been clarified, the Maldivian results broadly agreeing with island records in the eastern, rather than western Indian Ocean. Our results provide the first field evidence confirming geophysical model projections of a highstand 4-2 k.y. ago in the central Indian Ocean, though the observed level (+0.50 [+ or -] 0.1 m) is lower than that projected.

We report the first radiometric dates (thermal-ionization mass spectrometry) from late Pleistocene reef deposits from offshore Belize, the location of the largest modern reef complex in the Atlantic Ocean. The results presented here can be used to explain significant differences in bathymetry, sedimentary facies, and reef development of this major reef area, and the results are significant because they contribute to the knowledge of the regional geology of the eastern Yucatan. The previously held concept of a neotectonically stable eastern Yucatan is challenged. The dates indicate that Pleistocene reefs and shallow-water limestones, which form the basement of modern reefs in the area, accumulated ca. 125-130 ka. Significant differences in elevation of the samples relative to present sea level (>10 m) have several possible causes. Differential subsidence along a series of continental margin fault blocks in combination with variation in karstification are probably the prime causes. Differential subsidence is presumably related to initial extension and later left-lateral movements along the adjacent active boundary between the North American and Caribbean plates. Increasing dissolution toward the south during Pleistocene sea-level lowstands is probably a consequence of higher precipitation rates in mountainous southern Belize. Keywords: Belize, Pleistocene, reef, U-series dating.

Incipient speciation and restricted gene flow have been studied in disjunct Sea of Cortez and Pacific Ocean populations of a reef fish species, opaleye, or Girella nigricans. Individual fish were in three clades, one in the Sea of Cortez, a Pacific one south of Punta Eugenia, and a Pacific one north of Punta Eugenia.

A day in the field for Justin Suca begins at 4:45 in the morning, just before the first stars begin to disappear from the sky over the island of St. [...]

Early Pleistocene reefs on the eastern cost of Jamaica exhibit different faunas from the shallow parts of the reefs. Plaeozoic-type biotas such as brachiopods adn crinoids are located in deeper water, but are not easily available or studied. The older Pleistocene faunas are more accessible and informative.

A database of pre-Quaternary Phanerozoic reefs is used to test the significance of ancient reefs as paleoclimatic tracers. The compilation of reef paleolatitudes through time and comparison with published paleoclimate curves shows that neither the width of the tropical reef zone nor the total latitudinal range of reefs is correlated with published estimates of paleotemperature. However, reefs trace paleoclimate indirectly: Algal reefs tend to prevail during icehouse climatic intervals, and distinct high-latitude reefs are only developed in cold intervals, whereas during greenhouse episodes, the reef zone usually ended abruptly at a particular latitudinal boundary in the subtropics. Additionally, different biotic reef types tended to be concentrated in different latitudes. The lowest latitudes have usually been occupied by coralline sponge or microbial reefs, coral reefs tended to grow in intermediate latitudes, and bryozoan reefs constantly occupied the highest latitudinal position. Keywords: paleoclimate, paleolatitude, reef builders, reefs, secular variations.

While descriptive data can suggest that the diverse communities of fish on coral reefs are closely co-evolved, equilibrial assemblages of species, these are highly dynamic, non-equilibrial assemblages with structure driven more by patterns of recruitment of individual species, than by patterns of resource allocation among differently adapted phenotypes. As a consequence, local assemblages differ in structure, and structure wanders through time. Individual fish are confronted by different mixes of species in different times and places. The recruitment process that drives these dynamics is complex, being driven by several mechanisms, and local populations receive some portion of their recruitment from distant sources. Information on this connectivity among local populations is critically important for management which is based increasingly on use of marine protected areas (no-take zones) both to conserve, and to provide sustainable fisheries. At present, however, we do not know the spatial scale or the extent of this connectivity, and this critical knowledge gap impedes both management, and fundamental understanding. I will outline, and present preliminary results from ECONAR, a regional scale, multi-disciplinary project to delineate the scale and extent of this connectivity.

To gain insight into suborganismal mechanisms underlying responses of predators to environmental stress, we examined the effects of temperature and food availability on the physiology and feeding activity of the predatory whelk Nucella ostrina (formerly N. emarginata). Studies were conducted in the mid-low transition zone on rocky reefs at two sites on the Oregon coast: Strawberry Hill (SH) and Boiler Bay (BB). SH is dominated by suspension-feeding invertebrates and their predators, while BB is dominated by macrophytes. In wave-exposed (EX) and wave-protected (PR) habitats at each site, we measured air and water temperatures, whelk body temperatures, and indices of physiological condition (malate dehydrogenase [MDH] activities and RNA: DNA ratios) for wild-caught whelks. The influence of food ([+ or -] prey) and thermal conditions ([+ or -] shelter) on prey consumption, physiological performance (oxygen consumption rate), and response to thermal stress (induction of Hsp70-class stress proteins) of whelks was determined in field experiments. Low-tide air temperatures, whelk body temperatures, and biochemical indices of whelk field condition were consistently different between sites (SH > BB) and wave exposures (temperatures: PR > EX, condition: PR < EX). Foraging activity, metabolic rates, and stress protein (Hsp) expression were consistently higher at SH than BB. Respiration rates were lower for all -prey treatments than for +prey treatments; however, whelks in -prey +shade treatments had lower Hsp expression and higher respiration rates (an indication of better physiological condition) than whelks in -prey -shade treatments. Most measures of performance suggested that wave-exposed individuals were more physiologically robust than wave-protected individuals. Temporal physiological responses to stress suggested that high levels of heat stress compromise whelk performance later in the summer. These data are consistent with the hypothesis that physiological stress interacts with prey abundance to modify activity of whelks. Detailed studies of the effects of environmental stress on predator-prey interactions are needed to elucidate the relationship between physiological stress and predator-prey interactions. However, present evidence suggests that whelks alter activity (behavioral modification) and physiology (biochemical modification) in ways that lead to differential impacts by these predators on prey populations at different sites. Key words: community structure; enzymes; food availability; heat shock proteins; mussels; Mytilus; Nucella; oxygen consumption rates, RNA: DNA; rocky intertidal; wave exposure; whelks.

Specific fishing guidelines are important in preserving the ecological function of coral reefs. Overharvesting not only results in the depletion of a particular species, but endangers others that are dependent on that species. To determine these guidelines, researchers should study reproductive outputs and growth curves, and the effects of experimental population reductions.