Live coral cover has declined precipitously on Caribbean reefs in recent decades. Acropora cervicornis coral has been particularly decimated, and few Western Atlantic Acropora spp. refugia remain. ...Coral Gardens, Belize, was identified in 2020 as a long-term refugium for this species. This study assesses changes in live A. cervicornis coral abundance over time at Coral Gardens to monitor the stability of A. cervicornis corals, and to explore potential threats to this important refugium. Live coral cover was documented annually from 2012-2019 along five permanent transects. In situ sea-surface temperature data were collected at Coral Gardens throughout the study period and compared with calibrated satellite data to calculate Maximum Monthly Mean (MMM) temperatures and Degree Heating Weeks (DHW). Data on bathymetry, sediment, substrate, herbivore abundance, and macroalgal abundance were collected in 2014 and 2019 to assess potential threats to Coral Gardens. Live coral cover declined at all five transect sites over the study period. The greatest loss of live coral occurred between 2016 and 2017, coincident with the earliest and highest maximum average temperatures recorded at the study site, and the passage of a hurricane in 2016. Structural storm damage was not observed at Coral Gardens, though live coral cover declined after the passage of the storm. Uranium-thorium (230Th) dating of 26 dead in situ fragments of A. cervicornis collected in 2015 from Coral Gardens revealed no correlation between coral mortality and tropical storms and hurricanes in the recent past. Our data suggest that several other common drivers for coral decline (i.e. herbivory, predation, sedimentation, pH) may likely be ruled out for Coral Gardens. At the end of the study period, Coral Gardens satisfied most criteria for refugium status. However, the early onset, higher mean, and longer duration of above-average temperatures, as well as intermittent temperature anomalies likely played a critical role in the stability of this refugium. We suggest that temperature stress in 2016 and perhaps 2015 may have increased coral tissue vulnerability at Coral Gardens to a passing hurricane, threatening the status of this unique refugium.
At least 4 species of callichirid shrimp coexist in the shallow marine settings of San Salvador Island, an isolated, small platform of the all-carbonates Bahama Archipelago, implying that ...interspecific competition or trophic niche segregation occurs between these shrimp species. Carbon and nitrogen stable isotope analyses were conducted on soft tissues of 3 callichirid species,
Neocallichirus cacahuate
,
N. grandimana
, and
N. maryae
, to determine the food sources for each species. These analyses revealed that the isotopic trophic niches for these 3 species do not overlap. The most important food source for all 3 species was manatee grass
Syringodium filiforme
. The second most important food source for
N. cacahuate
and
N. grandimana
was drifting seaweed
Sargassum
sp., whereas that for
N. maryae
was turtle grass
Thalassia testudium
. These food-source adaptations likely contribute to the high species diversity of callichirid shrimp in tropical settings such as those found on San Salvador Island.
Caribbean Acropora spp. corals have undergone a decline in cover since the second half of the twentieth century. Loss of these architecturally complex and fast-growing corals has resulted in ...significant, cascading changes to the character, diversity, and available eco-spaces of Caribbean reefs. Few thriving Acropora spp. populations exist today in the Caribbean and western North Atlantic seas, and our limited ability to access data from reefs assessed via long-term monitoring efforts means that reef scientists are challenged to determine resilience and longevity of existing Acropora spp. reefs. Here we used multiple dating methods to measure reef longevity and determine whether Coral Gardens Reef, Belize, is a refuge for Acropora cervicornis against the backdrop of wider Caribbean decline. We used a new genetic-aging technique to identify sample sites, and radiocarbon and high-precision uranium-thorium (U-Th) dating techniques to test whether one of the largest populations of extant A. cervicornis in the western Caribbean is newly established after the 1980s, or represents a longer-lived, stable population. We did so with respect for ethical sampling of a threatened species. Our data show corals ranging in age from 1910 (.sup.14 C) or 1915 (.sup.230 Th) to at least November 2019. While we cannot exclude the possibility of short gaps in the residence of A. cervicornis earlier in the record, the data show consistent and sustained living coral throughout the 1980s and up to at least 2019. We suggest that Coral Gardens has served as a refuge for A. cervicornis and that identifying other, similar sites may be critical to efforts to grow, preserve, conserve, and seed besieged Caribbean reefs.
Relative reactivities of a series of neutral ligated boranes L-BH3 (where L is NHC, amine, pyridine, or phosphine) and the cyanoborohydride anion have been assessed in Rh(II)-catalyzed B–H insertion ...reactions with methyl 2-phenyl-2-diazoacetate. Stable α-boryl ester products were isolated by flash chromatography in all cases except for the salt product from cyanoborohydride. All of the substrates were either comparable to or more reactive than 1,4-cyclohexadiene, which is one of the most reactive substrates in C–H insertion reactions. The range of reactivity between the most reactive pyridine-borane and the least reactive phosphine-borane is a factor of approximately 40.
Boron–hydrogen bond insertion reactions of N-heterocyclic carbene (NHC) boranes and diazoesters can be catalyzed by NHC-boryl iodides and produce stable α-NHC-boryl esters. The conditions of the ...reaction resemble the previous rhodium-catalyzed transformations (only the catalyst is different); however, the mechanisms of the two reactions are probably very different. The new boryl iodide catalyzed method is adept at producing α-substituted-α-NHC-boryl esters, and this has led to a family of NHC-boryl esters with amino acid and amino-acid-like side chains.
The corals
Acropora palmata
and
A. cervicornis
are important Caribbean reef-builders that have faced significant mortality in recent decades. While many studies have focused on the recent demise of ...these species, data from areas where
Acropora
spp. have continued to thrive are limited. Understanding the genetic diversity, recruitment, and temporal continuity of healthy populations of these threatened
Acropora
spp. and the hybrid they form (“
Acropora prolifera
”) may provide insights into the demographic processes governing them. We studied three reef sites with abundant
A. cervicornis
,
A. palmata
, and hybrid
Acropora
populations offshore of Ambergris Caye, Belize at Coral Gardens, Manatee Channel, and Rocky Point. Samples were collected from all three
Acropora
taxa. We used microsatellite markers to determine: (1) genotypic diversity; (2) dominant reproductive mode supporting local recruitment; (3) minimum and maximum genet age estimates for all three acroporids; and (4) the history of hybrid colonization at these sites. We found that
Acropora
populations were highly clonal with local recruitment primarily occurring through asexual fragmentation. We also estimated the ages of 10
Acropora
genets using recent methodology based on somatic mutation rates from genetic data. Results indicate minimum ages of 62–409 yr for
A. cervicornis,
187–561 yr for
A. palmata
, and 156–281 yr for the
Acropora
hybrids at these sites. Our data indicate that existing
A. cervicornis, A. palmata,
and
Acropora
hybrid genets persisted during the 1980s Caribbean-wide
Acropora
spp. collapse, suggesting that these sites have been a refuge for Caribbean
Acropora
corals. Additionally, our data suggest that formation of extant hybrid
Acropora
genets pre-dates the widespread collapse of the parent taxa.
Summary Background In survivors of Ebola virus disease, clinical sequelae including uveitis, arthralgia, and fatigue are common and necessitate systematic follow-up. However, the infection risk to ...health-care providers is poorly defined. Here we report Ebola virus RT-PCR data for body site and fluid samples from a large cohort of Ebola virus survivors at clinic follow-up. Methods In this cross-sectional cohort study, consecutive survivors of Ebola virus disease attending Kerry Town survivor clinic (Freetown, Sierra Leone), who had been discharged from the Kerry Town Ebola treatment unit, were invited to participate. We collected and tested axillary, blood, conjunctival, forehead, mouth, rectal, semen, urine, and vaginal specimens for presence of Ebola virus using RT-PCR. We regarded samples to be positive for Ebola virus disease if the cycle threshold was 40 or lower. We collected demographic data from survivors of their age, sex, time since discharge from the treatment unit, and length of acute admission in the Ebola treatment unit using anonymised standard forms. Findings Between April 2, and June 16, 2015, of 151 survivors of Ebola virus disease invited to participate, 112 (74%) provided consent. The median age of participants was 21·5 years (IQR 14–31·5) with 34 (30%) participants younger than 16 years. 50 (45%) of 112 participants were male. We tested a total of 555 specimens: 103 from the axilla, 93 from blood, 92 from conjunctiva, 54 from forehead, 105 from mouth, 17 from the rectum, one from semen, 69 from urine, and 21 from the vagina. The median time from Ebola treatment unit discharge to specimen collection was 142 days (IQR 127–159). 15 participants had a total of 74 swabs taken less than 100 days from discharge. The semen sample from one participant tested positive for Ebola virus at 114 days after discharge from the treatment unit; specimens taken from the axilla, blood, conjunctiva, forehead, mouth, rectum, and urine of the same participant tested negative. All specimens from the other 111 participants tested negative. Interpretation Patients recovering from Ebola virus disease who do not meet the case definition for acute disease pose a low infection risk to health-care providers 6 weeks after clearance of viraemia. Personal protective equipment after this time might be limited to standard barrier precautions, unless contact with fluids from sanctuary sites is envisaged. Funding Save the Children International, Public Health England.
Fiddler crabs (Brachyura: Ocypodidae: Uca) are important bioturbators globally in protected tropical and temperate marine intertidal to supratidal, muddy to sandy environments. Their burrow ...distribution patterns vary with specific substrate. The study area is a saltwort (Salicornia virginica) meadow in a high intertidal to supratidal zone bordered by mangroves on the northern end of Pigeon Creek, a slightly hypersaline lagoon on San Salvador Island. Here the mostly carbonate sand substrate is heavily burrowed by Uca (Leptuca) speciosa (Ives, 1891). Three micro-habitats were differentiated according to variations in vegetation cover and depth to groundwater, as follows: 1) a meadow wetland, commonly flooded during spring high tides and with dense, luxuriant S. virginica and intermediate substrate firmness values, which has the highest density of burrows and the widest range of burrow diameters with mid-range values in burrow depth and length - maintaining the best conditions for fiddler crabs that include individuals of different ages; 2) dryland with slightly more subaerial elevation and sparse vegetation with the highest substrate firmness values and lowest density of burrows, the burrows being deeper, longer, and exhibiting the lowest range of diameters - with less favorable burrowing conditions for only fully mature adults; 3) wetland with sparse vegetation in the high intertidal zone with lowest firmness values, lowest number of burrows, smallest burrow diameters, and shallowest and shortest burrows - favoring colonization mainly by juveniles. If burrows similar to those of this study were preserved as trace fossils, they should be assigned to the ichnospecies Psilonichnus tubiformis Fürsich, 1981. When ichnological features such as burrow densities and dimensions, along with sedimentological and stratigraphical data, are taken into account in ways similar to those of this neoichnological study, interpretations of paleoenvironmental conditions and burrowing crab paleopopulation distributions could be significantly improved.
Although sea urchins are critical for controlling macroalgae on heavily fished coral reefs, high densities threaten reefs, as urchins are also prodigous bioeroders. This study examined urchin ...population characteristics, bioerosion rates, their fish predators (Labridae), and potential competitors (Scaridae) on unprotected reefs and a reef within a marine protected area (MPA) in the lagoonal regions off Belize. Urchin density (<1 m^sup -2^) and bioerosion rates (0.2 kg CaCO^sub 3 ^m^sup -2 ^year^sup -1^) were lowest and members of the Labridae were the highest (20 fish 200 m^sup -3^) within the MPA, while several unprotected reefs had higher (18-40 m^sup -2^) urchin densities, lower Labridae abundances (1-3 fish 200 m^sup -3^), and bioerosion rates ranging from 0.3-2.6 kg CaCO^sub 3 ^m^sup -2^ year^sup -1^. Urchin abundances were inversely related to Labridae (wrasses and hogfish) densities; however, on reef ridges, low algal cover (15%), small urchin size (14 mm), and low proportion of organic material in urchin guts suggested food limitation. Both top-down (predation) and bottom-up factors (food limitation) likely contribute to the control of urchins, predominantly Echinometra viridis, off Belize, thereby potentially diminishing the negative impacts of bioerosion activities by urchins.PUBLICATION ABSTRACT
PDF
