Montastrea Annularis Research Articles

A mid-twentieth century reduction in tropical upwelling inferred from coralline trace element proxies

The Cariaco Basin is an important archive of past climate variability given its response to inter- and extratropical climate forcing and the accumulation of annually laminated sediments within an anoxic water column. This study presents high-resolution surface coral trace element records ( Montastrea annularis and Siderastrea siderea) from Isla Tortuga, Venezuela, located within the upwelling center of this region. A two-fold reduction in Cd/Ca ratios (3.5–1.7 nmol/mol) is observed from 1946 to 1952 with no concurrent shift in Ba/Ca ratios. This reduction agrees with the hydrographic distribution of dissolved cadmium and barium and their expected response to upwelling. Significant anthropogenic variability is also observed from Pb/Ca analysis, observing three lead maxima since 1920. Kinetic control of trace element ratios is inferred from an interspecies comparison of Cd/Ca and Ba/Ca ratios (consistent with the Sr/Ca kinetic artifact), but these artifacts are smaller than the environmental signal and do not explain the Cd/Ca transition. The trace element records agree with historical climate data and differ from sedimentary faunal abundance records, suggesting a linear response to North Atlantic extratropical forcing cannot account for the observed historical variability in this region.

The bacterial ecology of a plague-like disease affecting the Caribbean coral Montastrea annularis.

The bacterial communities associated with the Caribbean coral Montastrea annularis showing tissue lesions indicative of a White Plague (WP)-like disease were investigated. Two molecular screening techniques using bacterial 16S rDNA genes were used and demonstrated distinct differences between the bacterial communities of diseased and non-diseased coral tissues, and also in relation to the proximity of tissue lesions on diseased corals. Differences between non-diseased corals and the apparently healthy tissues remote from the tissue lesion in affected corals indicates a 'whole coral' response to a relatively small area of infection with a perturbation in the normal microbial flora occurring prior to the onset of visible signs of disease. These whole organism changes in the microbial flora may serve as a bioindicator of environmental stress and disease. There were striking similarities between the 16S rDNA sequence composition associated with the WP-like disease studied here and that previously reported in association with black band disease (BBD) in coral. Similarities included the presence of a potential pathogen, an alpha-proteobacterium identified as the causal agent of juvenile oyster disease (JOD). The WP-like disease studied here is apparently different to WP Type ii because the bacterial species previously identified as the causal agent of WP Type ii was not detected, although the symptoms of the two diseases are similar.

A novel method for the transport and analysis of genetic material from polyps and zooxanthellae of scleractinian corals

We have developed a new simple method for transport, storage, and analysis of genetic material from the corals Agaricia agaricites, Dendrogyra cylindrica, Eusmilia ancora, Meandrina meandrites, Montastrea annularis, Porites astreoides, Porites furcata, Porites porites, and Siderastrea siderea at room temperature. All species yielded sufficient DNA from a single FTA® card (19 μg–43 ng) for subsequent PCR amplification of both coral and zooxanthellar DNA. The D1 and D2 variable region of the large subunit rRNA gene (LSUrDNA) was amplified from the DNA of P. furcata and S. siderea by PCR. Electrophoresis yielded two major DNA bands: an 800-base pair (bp) DNA, which represented the coral ribosomal RNA (rRNA) gene, and a 600-bp DNA, which represented the zooxanthellar srRNA gene. Extraction of DNA from the bands yielded between 290 μg total DNA ( S. siderea coral DNA) and 9 μg total DNA ( P. furcata zooxanthellar DNA). The ability to transport and store genetic material from scleractinian corals without resort to laboratory facilities in the field allows for the molecular study of a far wider range and variety of coral sites than have been studied to date.

Strontium in coral aragonite: 1. Characterization of Sr coordination by extended absorption X-ray fine structure

Aragonite was analyzed from Porites lobata, Pavona gigantea, Pavona clavus, and Montastrea annularis corals by Sr K-edge extended absorption X-ray fine structure (EXAFS) and compared with aragonite, strontianite, and mechanically mixed standards. Bulk analyses were performed and data compared with equivalent micro-EXAFS analyses on small (∼400 μm 3) analytical volumes with a microfocused X-ray beam. As a result of the architecture of the coral skeleton, the crystals within the microanalytical volume are not randomly oriented, and the microanalytical X-ray absorption spectra show orientational dependence. However, refinement of bulk and microanalytical data provided indistinguishable interatomic distances and thermal vibration parameters in the third shell (indicative of Sr speciation). The Sr K-edge EXAFS of all the coral samples refine, within error, to an ideally substituted Sr in aragonite, in contrast to previous studies, in which significant strontianite was reported. Some samples from that study were also analyzed here. Strontianite may be less widely distributed in corals than previously thought.

Monitoring the coral disease, plague type II, on coral reefs in St. John, U.S. Virgin Islands.

In July 1997, conspicuous white patches of necrotic tissue and bare skeleton began to appear on scleractinian corals in several bays around St. John, US Virgin Islands. Analysis of diseased coral tissue from five different species confirmed the presence of a Sphingomonas-like bacterium, the pathogen for plague type II. To date, 14 species of hard corals have been affected by plague type II around St. John. This disease was monitored at Haulover and Tektite Reefs at depths of 7-12 meters. The study site at Tektite Reef has > 50% cover by scleractinian corals with 90% of hard corals being composed of Montastraea annularis. Monthly surveys at Tektite Reef from December 1997 to May 2001 documented new incidence of disease (bare white patches of skeleton) every month with associated loss of living coral and 90.5% of all disease patches occurred on M. annularis. The frequency of disease within transects ranged from 3 to 58%, and the area of disease patches ranged from 0.25 to 9000 cm2. The average percent cover by the disease within 1 m2 ranged from 0.01% (+/- 0.04 SD) to 1.74% (+/- 9.08 SD). Photo-monitoring of 28 diseased corals of 9 species begun in September 1997 at Haulover Reef revealed no recovery of diseased portions with all necrotic tissue being overgrown rapidly by turf algae, usually within less than one month. Most coral colonies suffered partial mortality. Very limited recruitment (e.g., of Agaricia spp., Favia spp. and sponges) has been noted on the diseased areas. This coral disease has the potential to cause more loss of live coral on St. John reefs than any other stress to date because it targets the dominant reef building species, M. annularis.

A high‐resolution calibration of Sr/Ca thermometry using the Caribbean coral Montastraea annularis

A relationship has been established between the Sr/Ca ratio in the skeleton of the scleractinian coral Montastraea annularis and sea surface water temperature in south Florida. In order to obtain this correlation, specimens of Montastraea annularis were transplanted to a site at a local reef where every two to three months throughout a 2‐year period the corals were stained with Alizarin‐red S and where water temperature, which annually ranges between ∼20° and 30°C, was continually monitored. At the end of the experimental period the coral skeleton was sampled at a rate of ∼50 samples per year, each sample corresponding to only around 20 μg of calcium carbonate. For the 2.5‐year period, the Sr/Ca ratio exhibited excellent correlation in the first year (R2 = 0.83; Sr/Ca (mmol/mol) = 10.11 − 0.0452 × SST (°C)), but a rather poorer correlation in the second year (R2 = 0.68; Sr/Ca (mmol/mol) = 10.09 − 0.0406 × SST (°C)). Averaging the data into monthly values for year 1, we determined a relationship of (Sr/Ca (mmol/mol) = 10.165 − 0.0471 × SST (°C). On the basis of the excellent correlation between temperature and Sr/Ca, we feel that this relationship is the most accurate. Discrepancies in the second year are suggested to arise from slight sampling errors relative to the stain lines.

Characterization of the bacterial consortium associated with black band disease in coral using molecular microbiological techniques.

The bacterial community associated with black band disease (BBD) of the scleractinian corals Diploria strigosa, Montastrea annularis and Colpophyllia natans was examined using culture-independent techniques. Two complementary molecular screening techniques of 16S rDNA genes [amplified 16S ribosomal DNA restriction analysis (ARDRA) of clone libraries and denaturing gradient gel electrophoresis (DGGE)] were used to give a comprehensive characterization of the community. Findings support previous studies indicating low bacterial abundance and diversity associated with healthy corals. A single cyanobacterial ribotype was present in all the diseased samples, but this was not the same as that identified from Phormidium corallyticum culture isolated from BBD. The study confirms the presence of Desulfovibrio spp. and sulphate-reducing bacteria that have previously been associated with the BBD consortium. However, the species varied between diseased coral samples. We found no evidence of bacteria from terrestrial, freshwater or human sources in any of the samples. We report the presence of previously unrecognized potential pathogens [a Cytophaga sp. and an alpha-proteobacterium identified as the aetiological agent of juvenile oyster disease (JOD)] that were consistently present in all the diseased coral samples. The molecular biological approach described here gives an increasingly comprehensive and more precise picture of the bacterial population associated with BBD. To understand the pathogenesis of BBD, our attention should be focused on the pervasive ribotypes identified in this study (the Cyanobacterium sp., the Cytophaga sp. and the JOD pathogen).

Seasonal fluctuations in the photosynthetic capacity of photosystem II in symbiotic dinoflagellates in the Caribbean reef-building coral Montastraea

The photosynthetic capacity of photosystem II (PS II) in symbiotic dinoflagellates (Symbiodinium sp.), as measured by analysis of chlorophyll fluorescence, was investigated in the primary Caribbean reef-building corals, Montastraea annularis and Montastraea faveolata, for 5 years and Montastraea franksi over 2 years in the Bahamas. Significant seasonal fluctuations in the quantum yield of charge separation (Fv/Fm) of PS II were found in all species at all depths, with the highest photosynthetic capacity consistently recorded between mid-winter and early spring and the lowest photosynthetic capacity occurring in the mid to late summer. Corals residing in shallow depths of 1–2 m showed the greatest fluctuations in Fv/Fm, whereas deeper corals (3–4 and 14 m depths) had consistently higher values of Fv/Fm. Densities of symbiotic dinoflagellates and photosynthetic pigments followed a similar pattern. Fluctuations of photosynthetic capacity showed a strong correlation with seasonal patterns of water temperature and light. Such seasonal shifts in photosynthetic capacity are most likely due to several biochemical processes in the algae that lead to alterations of both photoprotection and photodamage. While symbiont density changed significantly on a seasonal basis, visual signs of coral bleaching were noted only in the fall of 1995 and the spring and summer of 1998. Comparisons of photosynthetic capacity and the decrease in the number of symbionts and their subsequent recovery indicated that symbiont populations in this study had the ability to recover quickly following bleaching events, as long as continued physical perturbation (e.g. thermal stress) did not shorten the recovery phase. Large-scale bleaching events are best viewed as the end points of seasonal physiological variation in which photosynthetic capacity and density of symbiotic dinoflagellates are reduced to a lower level than during "non-bleaching" years.

Genetic evidence for a protozoan (phylum Apicomplexa) associated with corals of the Montastraea annularis species complex

Genetic evidence for a protozoan (phylum Apicomplexa) associated with corals of the Montastraea annularis species complex

X-Ray absorption spectroscopy of uranium at low ppm levels in coral skeletal aragonite

We performed X-ray absorption spectroscopy of uranium in three coral specimens and present results of analysis of U L-II edge XANES (X-ray absorption near edge structure) spectra. The XANES of two specimens, Pavona gigantea (collected live at Champion Island, Galapagos) and Pavona clavus (collected live from Bartolme, Galapagos) were most similar to XANES of model compounds of U 6+. In contrast, the XANES of a specimen of Montastrea annularis (Pleistocene age from an exposed reef terrace on Marie Galante, Guadeloupe) showed some features typical of spectra of model compounds of U 4+. These data and interpretations suggest that uranium is incorporated into coral skeletons chiefly in its oxidized U 6+ form. The uranium may be subject to postmortem subaerial reduction to U 4+, or may be replaced or enhanced by addition of U 4+ compounds.

Effect of the 1995-1996 bleaching event on polyp tissue depth, growth, reproduction and skeletal band formation in Montastraea annularis

Polyp tissue depth, skeletal extension rate, reproduction and density band formation were studied in 15 colonies of Montastraea annularis from October 1994 to September 1997 as part of a long-term field study. With the commencement of a bleaching event in September 1995, the effects of bleaching on these biological parameters were examined. Bleaching affected all the parameters investigated, but the speed of recovery of each parameter to pre-bleaching values differed. Tissue depth recovered the fastest, within 4 to 8 wk of regaining normal pigmentation. Once pigmentation and tissue depth had recovered, skeletal growth resumed at its pre-bleaching rate. Reproduction took the longest to recover and reproductive failure occurred in severely bleached colonies 1 yr after bleaching. Even after 2 yr, reproductive output remained reduced in previously bleached colonies when compared with previously unbleached ones, although all colonies had successfully completed gametogenesis and spawning. Among the reproductive parameters measured, gonad size recovered faster than the number of gonads per polyp (i.e. polyps produced a smaller number of full-sized gonads 2 yr after bleaching). In all colonies, bleached and unbleached, the 1995 annual high-density (HD) band, which formed at the time of the bleaching event, appeared more prominent and in some cases wider than the HD bands for the years that preceded and succeeded bleaching. Bleaching reduced skeletal extension rate, and the HD band that formed at the time of the bleaching event was most pronounced in colonies in which skeletal extension rate was reduced for the longest period of time (i.e. severely bleached colonies). In 1996, the year following the bleaching event, colonies that did not complete gametogenesis (i.e. severely bleached colonies) produced no distinct HD band, while those that completed gametogenesis (i.e. mildly bleached colonies) produced a distinct HD band. These findings suggest that an inverse relationship between skeletal extension rate and HD band prominence may occur in Montastraea annularis, and that the failure of severely bleached colonies to produce a HD band in 1996 might be related, not to bleaching, but rather to the lack of gonad development and spawning in these colonies.

Timing of reproduction in Montastraea annularis: relationship to environmental variables

The timing of reproduction was investigated in 15 colonies of Montastraea annularis located on the Port Royal Cays, Jamaica. Spawning occurred between Days 6 and 8 after August's and/or September's full moon. In the 14 wk prior to spawning, mean total gonad size increased from 0.30 ± 0.17 to 34.38 ± 13.20% of the polyp cross-sectional area. Gonad size was significantly correlated with temperature and light intensity, but was not correlated with photoperiod or rainfall. Spawning occurred in the month prior to the period of heaviest rainfall, when temperatures were at their maximum. A meta-analysis of spawning time and climatic conditions at 19 other geographical locations also showed that spawning occurs in those periods without heavy rainfall in which temperatures are warmest. The data presented here suggest that temperature is not the only environmental variable controlling the annual timing of coral spawning. Rather, the time of coral spawning is controlled by a combination of temperature and rainfall.

No habitat correlation of zooxanthellae in the coral genus Madracis on a Curaçao reef

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 227:221-232 (2002) - doi:10.3354/meps227221 No habitat correlation of zooxanthellae in the coral genus Madracis on a Curaçao reef O. E. Diekmann1,3,*, R. P. M. Bak1,2, L. Tonk3, W. T. Stam3, J. L. Olsen3 1Institute of Biodiversity and Ecosystem Dynamics, University of Amsterdam, PO Box 94766, 1090 GT, Amsterdam, The Netherlands 2Netherlands Institute for Sea Research (NIOZ), PO Box 59, 1790 AB, Den Burg, Texel, The Netherlands 3Department of Marine Biology, Centre for Ecological and Evolutionary Studies, University of Groningen, PO Box 14, 9750 AA, Haren, The Netherlands *Corresponding author. E-mail: o.e.diekmann@biol.rug.nl Address for correspondence: University of Groningen ABSTRACT: Symbiotic dinoflagellates belonging to the genus Symbiodinium (zooxanthellae) play an important role in ecological specialization and physiological adaptation in corals. We examined the diversity and depth distribution of zooxanthellae in 5 morphospecies of Madracis at the Buoy I study-reef on Curaçao, Netherlands Antilles. Following earlier studies, we examined length and sequence variation in the D1 and D2 domains of the nuclear rDNA, large subunit (LSU) of Madracis-associated zooxanthellae. Both RFLP and sequence comparisons showed that all 5 Madracis morphospecies host a single type of Symbiodinium belonging to phylogenetic Group B sensu Rowan. No correlation was found between zooxanthellae and habitat depth. The presence of the single, Type-B zooxanthellae in all Madracis morphospecies at Buoy I (and from 3 other biogeographic locations in the Caribbean) suggests that Œgeneralist¹ zooxanthellae-coral associations are equally successful over a range of habitats and that adaptations to different light and nutrient regimes are not necessarily dependent on the mix of zooxanthellae types or zonation with depth, as has been shown in the well-studied Montastraea annularis complex and Acropora cervicornis. A review of the current literature on zooxanthellae diversity in scleractinians (including biogeographic sampling for some species) shows that most species appear to harbor only 1 zooxanthellae type and that the 3 types of Symbiodinium (A, B, C sensu Rowan) are found at all depths and are thus potentially always available for acquisition. KEY WORDS: Corals · Zooxanthellae · Madracis · Symbiodinium · rDNA · Symbiosis · Brooder · Bleaching Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 227. Online publication date: February 13, 2002 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2002 Inter-Research.

Repopulation of Zooxanthellae in the Caribbean corals Montastraea annularis and M. faveolata following experimental and disease-associated bleaching.

Caribbean corals of the Montastraea annularis species complex associate with four taxa of symbiotic dinoflagellates (zooxanthellae; genus Symbiodinium) in ecologically predictable patterns. To investigate the resilience of these host-zooxanthella associations, we conducted field experiments in which we experimentally reduced the numbers of zooxanthellae (by transplanting to shallow water or by shading) and then allowed treated corals to recover. When depletion was not extreme, recovering corals generally contained the same types of zooxanthellae as they did prior to treatment. After severe depletion, however, recovering corals were always repopulated by zooxanthellae atypical for their habitat (and in some cases atypical for the coral species). These unusual zooxanthellar associations were often (but not always) established in experimentally bleached tissues even when adjacent tissues were untreated. Atypical zooxanthellae were also observed in bleached tissues of unmanipulated Montastraea with yellow-blotch disease. In colonies where unusual associations were established, the original taxa of zooxanthellae were not detected even 9 months after the end of treatment. These observations suggest that zooxanthellae in Montastraea range from fugitive opportunists and stress-tolerant generalists (Symbiodinium A and E) to narrowly adapted specialists (Symbiodinium B and C), and may undergo succession.

Zooxanthellae of the Montastraea annularis species complex: patterns of distribution of four taxa of Symbiodinium on different reefs and across depths.

Corals of the Montastraea annularis complex host several different dinoflagellates in the genus Symbiodinium. Here we address two questions arising from our previous studies of these associations on an offshore reef. First, do the same taxa and patterns of association (Symbiodinium A and B found in higher irradiance habitats than Symbiodinium C) occur on an inshore reef? Second, does M. franksi at the limits of its depth range host only Symbiodinium C, as it does at intermediate depths? In both surveys, a new Symbiodinium taxon and different patterns of distribution (assayed by analyses of small ribosomal subunit RNA genes [srDNA]) were observed. Inshore, a taxon we name Symbiodinium E predominated in higher irradiance habitats in M. franksi and its two sibling species; the only other zooxanthella observed was Symbiodinium C. Offshore, M. franksi mainly hosted Symbiodinium C, but hosted Symbiodinium A, B, C, and E in shallow water and Symbiodinium E and C in very deep water. Symbiodinium E may be stress-tolerant. Observed srDNA heterogeneity within samples of Symbiodinium B, C, and E is interpreted as variation across copies within this multigene family. Experimental bleaching of Symbiodinium C supported this interpretation. Thus sequences from natural samples should be interpreted cautiously.

Lead contamination in the Mexican Caribbean recorded by the coral Montastraea annularis (Ellis and Solander)

Lead contamination in the Mexican Caribbean recorded by the coral Montastraea annularis (Ellis and Solander)

Impacts of recreational SCUBA diving on coral communities of the Caribbean island of Grand Cayman

The impact of recreational SCUBA diving on coral reefs of the Cayman Islands, British West Indies, was assessed from 63 10-m video transects, filmed on reefs in the West Bay area of Grand Cayman. Three high use and three low use dive sites were sampled at distances of c. 15, 55 and 200 m from mooring buoys, in addition to three sites where no diving occurs. Both diver numbers and distance from buoys were found to show highly significant ( P<0.01) effects on hard coral cover and cover of the major reef-building coral, Montastrea annularis. Diver numbers also increased the amount of dead coral and coral rubble. Relative to overall hard coral cover, the proportion of massive corals was smallest at heavily dived sites, but there was a larger proportion of Agaricia spp. corals, dead coral and coral rubble at these sites. Our findings suggest the need for a new management approach if the Islands are to conserve the ecological and aesthetic qualities of their most popular dive sites.

The influence of ‘host release factor’ on carbon release by zooxanthellae isolated from fed and starved Aiptasia pallida (Verrill)

Symbiotic dinoflagellates (zooxanthellae) typically respond to extracts of host tissue with enhanced release of short-term photosynthetic products. We examined this ‘host release factor’ (HRF) response using freshly isolated zooxanthellae of differing nutritional status. The nutritional status was manipulated by either feeding or starving the sea anemone Aiptasia pallida (Verrill). The release of fixed carbon from isolated zooxanthellae was measured using 14C in 30 min experiments. Zooxanthellae in filtered seawater alone released approximately 5% of photosynthate irrespective of host feeding history. When we used a 10-kDa ultrafiltrate of A. pallida host tissue as a source of HRF, approximately 14% of photosynthate was released to the medium. This increased to over 25% for zooxanthellae from anemones starved for 29 days or more. The cell-specific photosynthetic rate declined with starvation in these filtrate experiments, but the decline was offset by the increased percentage release. Indeed, the total amount of released photosynthate remained unchanged, or even increased, as zooxanthellae became more nutrient deficient. Similar trends were also observed when zooxanthellae from A. pallida were incubated in a 3-kDa ultrafiltrate of the coral Montastraea annularis, suggesting that HRF in the different filtrates operated in a similar manner. Our results support the suggestion that HRF diverts surplus carbon away from storage compounds to translocated compounds such as glycerol.

Are free amino acids responsible for the 'host factor' effects on symbiotic zooxanthellae in extracts of host tissue?

Symbiotic dinoflagellates (`zooxanthellae') typically release short-term photosynthetic products and have enhanced photosynthesis when exposed to extracts of host tissue. Published evidence has indicated that free amino acids (FAA) at concentrations exceeding 40 mM are responsible for these `host factor' effects on zooxanthellae from sea anemones and corals. We have compared the ninhydrin-positive FAA concentrations of extracts of the symbiotic sea anemone Aiptasia pallida with their efficacy in eliciting these responses and found little effect on carbon release by freshly isolated A. pallida symbionts at concentrations up to 0.6 mM, the highest concentration of our samples. Extracts of the coral Montastraea annularis induced release from these algae at less than 0.1 mM FAA, but there was no correlation between total ninhydrin-positive FAA concentration and `host factor' activity. However, all of these preparations stimulated photosynthesis. We tested a range of concentrations (≤50 mM) of glycine, alanine and glutamic acid with the isolated A. pallida symbionts. There was a significant increase in the release of fixed carbon with increasing alanine concentrations, but not with the other two amino acids. There were no effects on photosynthesis. Our observations support other reports indicating that other compounds , or specific amino acids such as taurine and the mycosporine-like amino acids, are responsible for `host factor' effects.

Time‐averaged fluxes of lead and fallout radionuclides to sediments in Florida Bay

Recent, unmixed sediments from mud banks of central Florida Bay were dated using 210Pb/226Ra, and chronologies were verified by comparing sediment lead temporal records with Pb/Ca ratios in annual layers of coral (Montastrea annularis) located on the ocean side of the Florida Keys. Dates of sediment lead peaks (1978±2) accord with prior observations of a 6 year lag between the occurrence of maximum atmospheric lead in 1972 and peak coral lead in 1978. Smaller lags of 1–2 years occur between the maximum atmospheric radionuclide fallout and peaks in sediment temporal records of 137Cs and Pu. Such lags are consequences of system time averaging (STA) in which atmospherically delivered particle‐associated constituents accumulate and mix in a (sedimentary?) reservoir before transferring to permanent sediments and coral. STA model calculations, using time‐dependent atmospheric inputs, produced optimized profiles in excellent accord with measured sediment 137Cs, Pu, lead, and coral lead distributions. Derived residence times of these particle tracers (16±1, 15.7±0.7, 19±3, and 16±2 years, respectively) are comparable despite differences in sampling locations, in accumulating media, and in element loading histories and geochemical properties. For a 16 year weighted mean residence time, STA generates the observed 6 year lead peak lag. Evidently, significant levels of nondegradable, particle‐associated contaminants can persist in Florida Bay for many decades following elimination of external inputs. Present results, in combination with STA model analysis of previously reported radionuclide profiles, suggest that decade‐scale time averaging may occur widely in recent coastal marine sedimentary environments.