Energy reserves and metabolism as indicators of coral recovery from bleaching

With reduced zooxanthellae, chlorophyll a (Chl a), or both, concentrations, bleached corals rely on some combination of energy reserves (i.e., lipid, carbohydrate, protein) and heterotrophy to survive and recover. To understand the dynamics of energy reserves and metabolism during long-term recovery, Porites compressa and Montipora capitata corals were experimentally bleached in outdoor tanks for 1 month (treatment corals). Additional corals were maintained in separate tanks at ambient temperatures (control corals). Recovery occurred on the reef for 0, 1.5, 4, or 8 months. At 0 months all treatment corals were white in color, with lower Chl a, lipid, carbohydrate, protein, tissue biomass, and photosynthesis than control corals. During recovery, P. compressa replenished energy reserves and tissue biomass at 8 mo, long after photosynthesis and Chl a had recovered at 1.5 and 4 months, respectively. M. capitata replenished energy reserves at 1.5 months, despite decreased Chl a and photosynthesis levels. P. compressa depends on photosynthetically fixed carbon for recovery from bleaching, whereas M. capitata does not. Overall, M. capitata had a faster recovery rate than P. compressa for all measured variables except Chl a concentration. With intensifying bleaching, coral diversity on future reefs may favor species with faster recovery rates

Coral skeleton P/Ca proxy for seawater phosphate: Multi-colony calibration with a contemporaneous seawater phosphate record

A geochemical proxy for surface ocean nutrient concentrations recorded in coral skeleton could provide new insight into the connections between sub-seasonal to centennial scale nutrient dynamics, ocean physics, and primary production in the past. Previous work showed that coralline P/Ca, a novel seawater phosphate proxy, varies synchronously with annual upwelling-driven cycles in surface water phosphate concentration. However, paired contemporaneous seawater phosphate time-series data, needed for rigorous calibration of the new proxy, were lacking. Here we present further development of the P/Ca proxy in Porites lutea and Montastrea sp. corals, showing that skeletal P/Ca in colonies from geographically distinct oceanic nutrient regimes is a linear function of seawater phosphate (PO4 SW) concentration. Further, high-resolution P/Ca records in multiple colonies of Pavona gigantea and Porites lobata corals grown at the same upwelling location in the Gulf of Panama were strongly correlated to a contemporaneous time-series record of surface water PO4 SW at this site (r2 = 0.7–0.9). This study supports application of the following multi-colony calibration equations to down-core records from comparable upwelling sites, resulting in ±0.2 and ±0.1 lmol/kg uncertainties in PO4 SW reconstructions from P. lobata and P. gigantea, respectively.P/Ca Porites lobata (lmol/mol) = (21.1 ? 2.4)PO4 SW (lmol/kg) + (14.3 ? 3.8)P/Ca Pavona gigantea (lmol/mol) = (29.2 ? 1.4)PO4 SW (lmol/kg) + (33.4 ? 2.7)Inter-colony agreement in P/Ca response to PO4 SW was good (±5–12% about mean calibration slope), suggesting that species-specific calibration slopes can be applied to new coral P/Ca records to reconstruct past changes in surface ocean phosphate. However, offsets in the y-intercepts of calibration regressions among co-located individuals and taxa suggest that biologically-regulated “vital effects” and/or skeletal extension rate may also affect skeletal P incorporation. Quantification of the effect of skeletal extension rate on P/Ca could lead to corrected calibration equations and improved inter-colony P/Ca agreement. Nevertheless, the efficacy of the P/Ca proxy is thus supported by both broad scale correlation to mean surface water phosphate and regional calibration against documented local seawater phosphate variations

Decadal timescale shift in the ^14C record of a central equatorial Pacific coral

Coral skeletal radiocarbon records reflect seawater Δ^14C and are useful for reconstructing the history of water mass movement and ventilation in the tropical oceans. Here, we reconstructed the inter-annual variability in central equatorial Pacific surface water Δ^14C from 1922–1956 using near-monthly 14C measurements in a Porites sp. coral skeleton (FI5A) from the windward side of Fanning Island (3°54'32"N, 159°18'88"W). The most pronounced feature in this record is a large, positive shift in the Δ^14C between 1947 and 1956 that coincides with the switch of the Pacific Decadal Oscillation (PDO) from a positive to a negative phase in the mid-1940s. Although the absolute Δ^14C values from 1950–1955 in FI5A differ from the Δ^14C values of another coral core collected from the opposite side of the island, both records show a large, positive shift in their Δ^14C records at that time. The relative increase in the Δ^14C of each record is consistent with the premise that a common mechanism is controlling the Δ^14C records within each coral record. Overall, the Fanning Δ^14C data support the notion that a significant amount of subtropical seawater is arriving at the Equator, but does not allow us to determine the mechanism for its transport

Photoacclimatization by the coral Montastraea cavernosa in the mesophotic zone: light, food, and genetics

Most studies on coral reefs have focused on shallow reef (<30 m) systems due to the technical limitations of conducting scientific diving deeper than 30 m. Compared to their shallow-water counterparts, these mesophotic coral reefs (30–150 m) are understudied, which has slowed our broader understanding of the biodiversity, ecology, and connectivity of shallow and deep coral reef communities. We know that the light environment is an important component of the productivity, physiology, and ecology of corals, and it restricts the distribution of most species of coral to depths of 60 m or less. In the Bahamas, the coral Montastraea cavernosa has a wide depth distribution, and it is one of the most numerous corals at mesophotic depths. Using a range of optical, physiological, and biochemical approaches, the relative dependence on autotrophy vs. heterotrophy was assessed for this coral from 3 to 91 m. These measurements show that the quantum yield of PSII fluorescence increases significantly with depth for M. cavernosa while gross primary productivity decreases with depth. Both morphological and physiological photoacclimatization occurs to a depth of 91 m, and stable isotope data of the host tissues, symbionts, and skeleton reveal a marked decrease in productivity and a sharp transition to heterotrophy between 45 and 61 m. Below these depths, significant changes in the genetic composition of the zooxanthellae community, including genotypes not previously observed, occur and suggest that there is strong selection for zooxanthellae that are suited for survival in the light-limited environment where mesophotic M. cavernosa are occurring

Pre-treatment effects on coral skeletal delta\u3csup\u3e13\u3c/sup\u3eC and delta\u3csup\u3e18\u3c/sup\u3eO

Pre-treatments are often used to remove organic “contaminant” material prior to isotopic analyses of coral skeletal samples. Here we conducted three experiments to test the pre-treatment effect of water, 30% hydrogen peroxide (H2O2), and household bleach [5.25% sodium hypochlorite (NaClO3) and 0.15% sodium hydroxide (NaOH)], on the stable isotopic composition of coral skeletal samples. First, using a mass balance approach we calculated the expected change in skeletal delta13C due to the removal of all organic carbon. The model showed that (1) the removal of organic carbon (which has a low delta13C value relative to skeletal delta13C) from the skeletal sample should theoretically result in a higher delta13C value of the remaining organic-carbon-free carbonate, and that (2) only at the highest concentrations of skeletal organic carbon within the tissue layer of corals is the contribution of the organic carbon to the overall delta13C skeletal value potentially large enough to be detectable by mass spectrometry. We then conducted two sets of experiments to test the model where we pre-treated a large number of skeletal samples from five species of corals with water, H2O2, bleach, or no pre-treatment for 24 h. Skeletal delta13C generally decreased significantly with water, bleach, and H2O2 pre-treatments which is contrary to the model-predicted increase in delta13C following such pre-treatments. Thus, organic carbon within the skeleton is not a net source of contamination to delta13C analyses. Skeletal delta18O decreased the most with water and bleach pre-treatments. In addition, the effect of H2O2 or bleach pre-treatments on either delta13C or delta18O was not consistent among species or locations. The direction of change in delta13C and delta18O with pre-treatments was no different for skeletal samples taken within or below the tissue layer. Based on our results, we suggest that pre-treatment is not necessary and recommend that pre-treatment not be performed on coral skeletal samples prior to stable isotope analysis to avoid any pre-treatment-induced variability that could significantly compromise inter-colony and inter-species comparisons

Increased prevalence of impulse control disorder symptoms in endocrine diseases treated with dopamine agonists: a cross-sectional study

INTRODUCTION: Impulse control disorders (ICDs) have been described as a side effect of dopamine agonists (DAs) in neurological as well as endocrine conditions. Few studies have evaluated the neuropsychological effect of DAs in hyperprolactinemic patients, and these have reported a relationship between DAs and ICDs. Our objective was to screen for ICD symptoms in individuals with DA-treated endocrine conditions. MATERIALS AND METHODS: A cross-sectional analysis was conducted on 132 patients with pituitary disorders treated with DAs (DA exposed), as well as 58 patients with pituitary disorders and no history of DA exposure (non-DA exposed). Participants responded to the full version of the Questionnaire for Impulsive-Compulsive Disorders in Parkinson’s disease (QUIP). RESULTS: Compared with the non-DA-exposed group, a higher prevalence of DA-exposed patients tested positive for symptoms of any ICD or related behavior (52% vs. 31%, p < 0.01), any ICD (46% vs. 24%, p < 0.01), any related behavior (31% vs. 17%, p < 0.05), compulsive sexual behavior (27% vs. 14%, p < 0.04), and punding (20% vs. 7%, p < 0.02) by QUIP. On univariate analysis, DA treatment was associated with a two- to threefold increased risk of any ICD or related behavior [odds ratio (OR) 2.43] and any ICD (OR 2.70). In a multivariate analysis, independent risk factors for any ICD or related behavior were DA use (adjusted OR 2.22) and age (adjusted OR 6.76). Male gender was predictive of the risk of hypersexuality (adjusted OR 3.82). DISCUSSION: Despite the QUIP limitations, a clear sign of increased risk of ICDs emerges in individuals with DA-treated pituitary disorders. Our data contribute to the growing evidence of DA-induced ICDs in endocrine conditions