Structurally complex habitats provided by Acropora palmata influence ecosystem processes on a reef in the Florida Keys National Marine Sanctuary

The disappearance of Acropora palmata from reefs in the Florida Keys National Marine Sanctuary (FKNMS) represents a significant loss in the amount of structurally complex habitat available for reef-associated species. The consequences of such a widespread loss of complex structure on ecosystem processes are still unclear. We sought to determine whether the disappearance of complex structure has adversely affected grazing and invertebrate predation rates on a shallow reef in the FKNMS. Surprisingly, we found grazing rates and invertebrate predation rates were lower in the structurally complex A. palmata branches than on the topographically simple degraded reefs. We attribute these results to high densities of aggressively territorial damselfish, Stegastes planifrons, living within A. palmata. Our study suggests the presence of agonistic damselfish can cause the realized spatial patterns of ecosystem processes to deviate from the expected patterns. Reef ecologists must therefore carefully consider the assemblage of associate fish communities when assessing how the mortality of A. palmata has affected coral reef ecosystem processes.     

Assessing eukaryotic biodiversity in the Florida Keys National Marine Sanctuary through environmental DNA metabarcoding

Environmental DNA (eDNA) is the DNA suspended in the environment (e.g., water column), which includes cells, gametes, and other material derived from but not limited to shedding of tissue, scales, mucus, and fecal matter. Amplifying and sequencing marker genes (i.e., metabarcoding) from eDNA can reveal the wide range of taxa present in an ecosystem through analysis of a single water sample. Metabarcoding of eDNA provides higher resolution data than visual surveys, aiding in assessments of ecosystem health. This study conducted eDNA metabarcoding of two molecular markers (cytochrome c oxidase I (COI) and 18S ribosomal RNA (rRNA) genes) to survey eukaryotic diversity across multiple trophic levels in surface water samples collected at three sites along the coral reef tract within the Florida Keys National Marine Sanctuary (FKNMS) during four research cruises in 2015. The 18S rRNA gene sequences recovered 785 genera while the COI gene sequences recovered 115 genera, with only 33 genera shared between the two datasets, emphasizing the complementarity of these marker genes. Community composition for both genetic markers clustered by month of sample collection, suggesting that temporal variation has a larger effect on biodiversity than spatial variability in the FKNMS surface waters. Sequences from both marker genes were dominated by copepods, but each marker recovered distinct phytoplankton groups, with 18S rRNA gene sequences dominated by dinoflagellates and COI sequences dominated by coccolithophores. Although eDNA samples were collected from surface waters, many benthic species such as sponges, crustaceans, and corals were identified. These results show the utility of eDNA metabarcoding for cataloging biodiversity to establish an ecosystem baseline against which future samples can be compared in order to monitor community changes.     

Aerial and tidal transport of mosquito control pesticides into the Florida Keys National Marine Sanctuary

This project was undertaken as the initial monitoring program to determine if mosquito adulticides applied along the Florida Keys cause adverse ecological effects in the Florida Keys National Marine Sanctuary (FKNMS). The study monitored the distribution and persistence of two mosquito adulticides, permethrin and dibrom (naled), during three separate routine applications by the Florida Keys Mosquito Control District. The approach was to determine if toxic concentrations of the pesticides entered the FKNMS by aerial drift or tidal transport. The amount of pesticide entering the FKNMS by way of aerial drift was monitored by collection on glass fiber filter pads, set on floats in a grid pattern on either side of the FKNMS. Permethrin was recovered from filter pads on the leeward side for each of the three applications, ranging from 0.5 to 50.1 microg/m(2) throughout the study. Tidal current transport was monitored by collection of surface and subsurface water samples at each grid site. Tidal transport of naled and dichlorvos (naled degradation product) was apparent in the adjacent waters of the FKNMS. These compounds were detected in subsurface, offshore water at 0.1 to 0.6 microg/1, 14 hr after application. Permethrin was not detected in offshore water samples; however, concentrations ranging from 5.1 to 9.4 microg/l were found in surface water from the canal system adjacent to the application route. Comparison of the observed environmental concentrations with toxicity data (permethrin LC-50, 96 hr for Mysidopsis bahia = 0.02 microg/l) indicated a potential hazard to marine invertebrates in the canals with possible tidal transport to other areas.     

Larval influx of Diadema antillarum to the Florida Keys linked to passage of a Tortugas Eddy

Lack of recovery of the sea urchin Diadema antillarum in the Caribbean region following a widespread epizootic in 1983–1984 has garnered great interest due to the role of this species as a grazer of macroalgae that exclude reef-building corals. In the Florida Keys, USA, previous research suggests that reestablishment of D. antillarum is limited by low fertilization success and a lack of larval supply. However, the physical mechanisms determining larval supply in the Florida Keys remain poorly resolved. Here, we use coupled biological and physical oceanographic datasets of D. antillarum larval supply to settlement collectors, sea surface temperatures and heights, and the Okubo Weiss parameter to examine a link between influx of larvae to the middle Florida Keys and Tortugas Eddy activity in the Straits of Florida. The greatest magnitude of settlement over 3 months of measurements occurred from late May to late June 2015, coinciding with the passage and dissociation of a Tortugas Eddy. Settlement occurred on collectors only at offshore bank-barrier reef sites, consistent with a temperature signal of a passing eddy at these sites. No D. antillarum were observed by divers at sites 1 yr following settlement on the collectors. The results indicate that despite the lack of population recovery, D. antillarum larval influx can occur during intermittent oceanographic events.

     

Effects of excluding bottom-disturbing mobile fishing gear on abundance and biomass of groundfishes in the Stellwagen Bank National Marine Sanctuary,USA

<正> The Stellwagen Bank National Marine Sanctuary (southern Gulf of Maine, northwest Atlantic) is partially overlappedby the Western Gulf of Maine Closure Area (WGMCA). This is a region in which mobile, bottom-disturbing fishing gear has beenbanned by the New England Fishery Management Council to facilitate the rebuilding of depleted groundfish populations. We assessedthe effects and effectiveness of the WGMCA on groundfish assemblages using habitat-stratified (gravel, sand, mixed benthichabitats) sampling by means of a commercial trawler, inside and outside of the WGMCA. Sampling occurred over threemonth-long sampling periods in 2004-2005, two during the spring seasons and one during the fall season. A total of 18 specieswere analyzed for protection effects. After controlling for substratum, location and sampling season, eight groundfish species exhibitedhigher mean proportional abundance inside than outside the WGMCA while two were proportionally more abundant onaverage outside of the closure. Four species had higher mean proportional biomasses on average inside the closure and three outside.We conclude that the WGMCA may be achieving its goal of rebuilding abundance and biomass for some commercially targetedgroundfishes but not all. This study, six to seven years post-closure establishment, reveals fine-scale spatial and taxonomiccomplexity which will require a very different monitoring protocol than the one currently in place if adaptive management is to besuccessful in the region     

Effects of excluding bottom-disturbing mobile fishing gear on abundance and biomass of groundfishes in the Stellwagen Bank National Marine Sanctuary, USA

The Stellwagen Bank National Marine Sanctuary (southern Gulf of Maine, northwest Atlantic) is partially overlapped by the Western Gulf of Maine Closure Area (WGMCA). This is a region in which mobile, bottom-disturbing fishing gear has been banned by the New England Fishery Management Council to facilitate the rebuilding of depleted groundfish populations. We assessed the effects and effectiveness of the WGMCA on groundfish assemblages using habitat-stratified (gravel, sand, mixed benthic habitats) sampling by means of a commercial trawler, inside and outside of the WGMCA. Sampling occurred over three month-long sampling periods in 2004-2005, two during the spring seasons and one during the fall season. A total of 18 species were analyzed for protection effects. After controlling for substratum, location and sampling season, eight groundfish species exhibited higher mean proportional abundance inside than outside the WGMCA while two were proportionally more abundant on average outside of the closure. Four species had higher mean proportional biomasses on average inside the closure and three outside. We conclude that the WGMCA may be achieving its goal of rebuilding abundance and biomass for some commercially targeted groundfishes but not all. This study, six to seven years post-closure establishment, reveals fine-scale spatial and taxonomic complexity which will require a very different monitoring protocol than the one currently in place if adaptive management is to be successful in the region [Current Zoology 56 (1): 134-143, 2010].     

Restoration and monitoring of a vessel grounding on a shallow reef in the Florida Keys

This paper summarizes the results of a monitoring event designed to track the recovery of a repaired coral reef injured by the M/V Alec Owen Maitland vessel grounding incident of October 25, 1989. This grounding occurred within the Florida Keys National Marine Sanctuary. Pursuant to the National Marine Sanctuaries Act, NOAA recovers money for injury to Sanctuary resources, and uses it to restore those resources. A monitoring program tracks patterns of recovery, in order to determine the success of restoration measures. To evaluate success, reference habitats adjacent to the restoration site are concurrently monitored to compare the condition of restored areas with natural areas. Restoration of this site was completed in September 1995 by means of cement and limestone rock, and the monitoring results from summer 2007 are presented. Monitoring consisted of comparison of the biological conditions in the restored area with the reference area. Monitored corals are divided into the Orders: Gorgonians, Milleporans, and Scleractinians. Densities at the restored and reference areas are compared, and are shown to be greater in the restored. Size-class frequency distributions for the most abundant Scleractinians are examined, and reveal that the restoration is converging on the reference area. Also, for the Scleractinians, number and percentage of colonies by species, as well as several common biodiversity indices are provided; measures for the restored area approximate the reference area. A quantitative comparison of colony substrate settlement preference in the restored area is provided for all Orders, and for Scleractinians is further broken down for the two most frequent Genera.     

Evidence of photoacclimatization at mesophotic depths in the coral-Symbiodinium symbiosis at Flower Garden Banks National Marine Sanctuary and McGrail Bank

Coral Reefs - Similar to shallower conspecifics, mesophotic scleractinian corals found at ~ 30–150&nbsp;m depths maintain important symbioses with photosynthetic microalgae in the...     

Fish assemblages on artificial and natural reefs in the Flower Garden Banks National Marine Sanctuary, USA

 Visual censusing was used to characterize fish assemblages on artificial and natural reefs located within the boundaries of the Flower Garden Banks National Marine Sanctuary (FGBNMS) in the northwestern Gulf of Mexico. Emphasis was placed on determining spatial and temporal patterns in habitat utilization by fishes on an offshore artificial reef (Mobil Platform HI-A389A). Overall, 43 species were observed during diurnal surveys in the upper 24 m of the artificial reef. Midwater pelagic fishes (i.e., carangids and scombrids) accounted for over 50% of all taxa enumerated on the artificial reef; however, these taxa were transient members of the assemblage and were observed infrequently. Labrids, pomacentrids, and serranids were the dominant reef-dependent taxa. Distinct trends in vertical, diel, and seasonal abundances were observed for juvenile and adult fishes. Of the three designated depth zones (upper 1.5–9.0, middle 9.0–16.5; lower 16.5–24.0 m), abundance and species diversity were lowest in the upper zone. Nocturnal counts were characterized by a marked reduction or complete absence of most species, due in part to twilight cover-seeking and movement activities. Seasonal variation in community composition and species abundance (May versus September) was primarily due to recruitment of juveniles (0-age fishes) to the artificial reef in late summer. Increases in total fish abundance (all taxa combined) coincided with both increasing habitat rugosity and degree of fouling. Species richness on natural coral reefs in the FGBNMS was higher than on the artificial reef. Unlike the artificial reef, fish assemblages on the natural reefs were dominated by a single family (Pomacentridae) which accounted for over 50% of all individuals observed. Accepted: 1 August 1996     

Temporal and Vertical Distributions of Bacterioplankton at the Gray's Reef National Marine Sanctuary

Large spatial scales and long-term shifts of bacterial community composition (BCC) in the open ocean can often be reliably predicted based on the dynamics of physical-chemical variables. The power of abiotic factors in shaping BCC on shorter time scales in shallow estuarine mixing zones is less clear. We examined the diurnal variation in BCC at different water depths in the spring and fall of 2011 at a station in the Gray''s Reef National Marine Sanctuary (GRNMS). This site is located in the transition zone between the estuarine plume and continental shelf waters of the South Atlantic Bight. A total of 234,516 pyrotag sequences of bacterial 16S rRNA genes were recovered; they were taxonomically affiliated with >200 families of 23 bacterial phyla. Nonmetric multidimensional scaling analysis revealed significant differences in BCC between spring and fall samples, likely due to seasonality in the concentrations of dissolved organic carbon and nitrate plus nitrite. Within each diurnal sampling, BCC differed significantly by depth only in the spring and differed significantly between day and night only in the fall. The former variation largely tracked changes in light availability, while the latter was most correlated with concentrations of polyamines and chlorophyll a. Our results suggest that at the GRNMS, a coastal mixing zone, diurnal variation in BCC is attributable to the mixing of local and imported bacterioplankton rather than to bacterial growth in response to environmental changes. Our results also indicate that, like members of the Roseobacter clade, SAR11 bacteria may play an important role in processing dissolved organic material in coastal oceans.     

Surface Ultrastructure of Some Tests of Recent Foraminiferida from the Dry Tortugas, Florida

SYNOPSIS. The surface ultrastructure of 10 species of benthic Foraminiferida from the Dry Tortugas, Florida, has been investigated using an electron microscope. Tests of miliolid Foraminiferida appear to be made up of at least 2 distinct layers. An outermost pavement-like layer, consisting of a single layer of calcite rhombohedrons, and an underlying "randomly oriented layer" comprise most of the wall thickness. It was possible to differentiate each miliolid species on the basis of a statistical analysis of calcite rhombs making up the pavement-like layer. Pseudopores were found on the tests of Miliolinella subrotunda (Montagu) and Archaias angulatus (Fichtel and Moll). None of these pseudopores completely penetrated the wall, and all floored in the "randomly oriented layer." It is believed that these structures are formed at time of calcification, rather than secondarily at some later time.
Calcification in Foraminiferida appears to be a biphasic process similar to that found in most other organisms. Groups of crystals were discernible on surfaces of most porcelaneous and "radiate" calcareous species. This suggests that parallel growth of crystals may be an important process in calcification of many Foraminiferida.
A sieve-plate was found in a canal paralleling the test's surface in Cymbaloporetta squammosa (d'Orbigny).     

Fish Species and Community Distributions as Proxies for Seafloor Habitat Distributions: The Stellwagen Bank National Marine Sanctuary Example (Northwest Atlantic, Gulf Of Maine)

Defining the habitats of fishes and associated fauna on outer continental shelves is problematic given the paucity of data on the actual types and distributions of seafloor habitats. However many regions have good data on the distributions of fishes from resource surveys or catch statistics because of the economic importance of the fisheries. Fish distribution data (species or communities) have been used as a proxy for the distribution of habitats to develop precautionary conservation strategies for habitat protection (e.g., marine protected areas, fishing gear restrictions). In this study we assessed the relationships between the distributions of fish communities and species derived from trawl survey data with the spatial distribution of sediment types determined by sampling and acoustic reflectance derived from multibeam sonar surveys in Stellwagen Bank National Marine Sanctuary. Fish communities were correlated with reflectance values but all communities did not occur in unique sediment types. This suggests that use of community distributions as proxies for habitats should include the caveat that a greater number of communities within an area could indicate a greater range of habitat types. Single species distributions showed relationships between abundance and reflectance values. Trawl catches with low abundances had wide variations in reflectance values while those with high abundances had narrower ranges indicating habitat affinities. Significant non-random frequency-dependent relationships were observed for 17 of 20 species although only 12 of 20 species had significant relationships based on rank correlation. These results suggest that species distributions based on trawl survey data can be used as proxies for the distribution of seafloor habitats. Species with known habitat associations can be used to infer habitat requirements of co-occurring species and can be used to identify a range of habitat types.     

Gambierdiscus (Dinophyceae) species diversity in the Flower Garden Banks National Marine Sanctuary,Northern Gulf of Mexico,USA

Globally, ciguatera fish poisoning (CFP) is the principal cause of non-bacterial illness associated with seafood consumption. The toxins (ciguatoxins) responsible for CFP are produced by dinoflagellates in the genus Gambierdiscus, which are endemic to tropical and sub-tropical areas. Ciguatoxins are lipophilic and bioaccumulate in marine food webs, typically reaching their highest concentrations in fish. Following a CFP event in 2008, the U.S. Food and Drug Administration (USFDA) issued a ciguatera toxin alert that included fish harvested in the northern Gulf of Mexico in and near the Flower Garden Banks National Marine Sanctuary (FGBNMS). The East Flower Garden Bank (EFGB) and West Flower Garden Bank (WFGB) are characterized by thriving coral communities that support Gambierdiscus growth. This study was undertaken specifically to document the diversity of Gambierdiscus species present in the sanctuary that may be sources of ciguatoxins entering the food web. Samples collected from the FGBNMS over a three year period were screened using species-specific polymerase chain reaction assays. A diverse assemblage of Gambierdiscus species was distributed to depths of >45 m, a new depth record for Gambierdiscus. Gambierdiscus belizeanus, Gambierdiscus caribaeus, Gambierdiscus carolinianus, Gambierdiscus carpenteri and Gambierdiscus ribotype 2 were all found on both East and West FGB with Gambierdiscus ruetzleri also recorded from the WFGB. The most common species was G. carolinianus, originally identified from samples collected between 35 and 40 m off the coast of NC, USA. Our findings are consistent with recent physiological studies showing that some Gambierdiscus species can grow year round at the temperatures and salinities at the FGBNMS and at light levels as low as 10 μmol photons m⁻² s⁻¹. Such irradiances are estimated to occur in the FGBNMS at depths of ∼70–80 m. The consistent recovery of Gambierdiscus species from deep sampling sites in areas known to produce ciguatoxic fish signals a substantial change in our concept of suitable habitats for Gambierdiscus to include depths greater than 50 m.