Morphological and Phylogenetic Description of an Unusual Amphidinium (Dinophyceae) Species

Amphidinium carterae, an important harmful algal species that produces powerful antifungal and hemolytic compounds (amphidinols) and cytotoxic macrolides (amphidinolides) is ubiquitous in coastal waters. Samples from coral rubble contained an unusual and previously unreported Amphidinium (D2) with a circular outline. Genetic analysis of clone D2 of this species, involving the sequencing of large subunit (LSU) rDNA, revealed a relationship between Amphidinium sp. D2 and both A. carterae and A. massartii. However, morphological and genetic differences suggest that Amphidinium sp. D2 is not conspecific with A. carterae or A. massartii. Further studies to describe this species are presently underway

Hysteresis Between Coral Reef Calcification and the Seawater Aragonite Saturation State

Some predictions of how ocean acidification (OA) will affect coral reefs assume a linear functional relationship between the ambient seawater aragonite saturation state (Ωa) and net ecosystem calcification (NEC). We quantified NEC in a healthy coral reef lagoon in the Great Barrier Reef during different times of the day. Our observations revealed a diel hysteresis pattern in the NEC versus Ωa relationship, with peak NEC rates occurring before the Ωa peak and relatively steady nighttime NEC in spite of variable Ωa. Net ecosystem production had stronger correlations with NEC than light, temperature, nutrients, pH, and Ωa. The observed hysteresis may represent an overlooked challenge for predicting the effects of OA on coral reefs. If widespread, the hysteresis could prevent the use of a linear extrapolation to determine critical Ωa threshold levels required to shift coral reefs from a net calcifying to a net dissolving state

Groundwater and Porewater as Major Sources of Alkalinity to a Fringing Coral Reef Lagoon (Muri Lagoon, Cook Islands)

To better predict how ocean acidification will affect coral reefs, it is important to understand how biogeochemical cycles on reefs alter carbonate chemistry over various temporal and spatial scales. This study quantifies the contribution of shallow porewater exchange (as quantified from advective chamber incubations) and fresh groundwater discharge (as traced by 222Rn) to total alkalinity (TA) dynamics on a fringing coral reef lagoon along the southern Pacific island of Rarotonga over a tidal and diel cycle. Benthic alkalinity fluxes were affected by the advective circulation of water through permeable sediments, with net daily flux rates of carbonate alkalinity ranging from −1.55 to 7.76 mmol m−2 d−1, depending on the advection rate. Submarine groundwater discharge (SGD) was a source of TA to the lagoon, with the highest flux rates measured at low tide, and an average daily TA flux of 1080 mmol m−2 d−1 at the sampling site. Both sources of TA were important on a reef-wide basis, although SGD acted solely as a delivery mechanism of TA to the lagoon, while porewater advection was either a sink or source of TA dependent on the time of day. This study describes overlooked sources of TA to coral reef ecosystems that can potentially alter water column carbonate chemistry. We suggest that porewater and groundwater fluxes of TA should be taken into account in ocean acidification models in order to properly address changing carbonate chemistry within coral reef ecosystems

Carbon Cycling Hysteresis in Permeable Carbonate Sands over a Diel Cycle: Implications for Ocean Acidification

Dissolved inorganic carbon, dissolved oxygen, H+, and alkalinity fluxes from permeable carbonate sediments at Heron Island (Great Barrier Reef) were measured over one diel cycle using benthic chambers designed to induce advective pore‐water exchange. A complex hysteretic pattern between carbonate precipitation and dissolution in sands and the aragonite saturation state (ΩAr) of the overlying chamber water was observed throughout the incubations. During the day, precipitation followed a hysteretic pattern based on the incidence of photosynthetically active radiation with lower precipitation rates in the morning than in the afternoon. The observed diel hysteresis seems to reflect a complex interaction between photosynthesis and respiration rather than ΩAr of the overlying water as the main driver of carbonate precipitation and dissolution within these permeable sediments. Changes in flux rates over a diel cycle demonstrate the importance of taking into account the short‐term variability of benthic metabolism when calculating net daily flux rates. Based on one diel cycle, the sediments were a net daily source of alkalinity to the water column (5.13 to 8.84 mmol m−2 d−1, depending on advection rates), and advection had a net stimulatory effect on carbonate dissolution. The enhanced alkalinity release associated with benthic metabolism and pore‐water advection may partially buffer shallow coral reef ecosystems against ocean acidification on a local scale

Nitrous Oxide and Methane Dynamics in a Coral Reef Lagoon Driven by Pore Water Exchange: Insights from Automated High‐Frequency Observations

Automated cavity ring down spectroscopy was used to make continuous measurements of dissolved methane, nitrous oxide, and carbon dioxide in a coral reef lagoon for 2 weeks (Heron Island, Great Barrier Reef). Radon (222Rn) was used to trace the influence of tidally driven pore water exchange on greenhouse gas dynamics. Clear tidal variation was observed for CH4, which correlated to 222Rn in lagoon waters. N2O correlated to 222Rn during the day only, which appears to be a response to coupled nitrification‐denitrification in oxic sediments, fueled by nitrate derived from bird guano. The lagoon was a net source of CH4 and N2O to the atmosphere and a sink for atmospheric CO2. The estimated pore water‐derived CH4 and N2O fluxes were 3.2‐fold and 24.0‐fold greater than the fluxes to the atmosphere. Overall, pore water and/or groundwater exchange were the only important sources of CH4 and major controls of N2O in the coral reef lagoon

Non-conservative Behavior of Dissolved Organic Matter and Trace Metals (Mn, Fe, Ba) Driven by Porewater Exchange in a Subtropical Mangrove-Estuary

Estuaries play a key role in controlling the land-ocean fluxes of dissolved organic matter (DOM), nutrients and trace metals. Here, we study how mangrove-fringed areas affect the molecular DOM and trace metal composition in a subtropical estuary. We combined molecular analysis of solid-phase extractable (SPE) DOM using ultrahigh-resolution mass spectrometry with organic and inorganic bulk parameter analyses in surface and porewater along the estuarine gradient of a mangrove-fringed estuary in Australia (Coffs Creek). Statistical analysis and mixing models demonstrate that the fluvial and mangrove-porewater derived DOM and inorganic chemical species were altered and/or removed by the estuarine filter before reaching the coastal ocean. The mangrove-fringed central estuary was a net source for dissolved Mn and Ba as well as total dissolved nitrogen (TDN) and dissolved organic carbon (DOC) to the tidal creek, likely due to the exchange of mangrove-porewater strongly enriched in these constituents. Dissolved Fe was removed from the water column, probably during the tidally driven circulation of creek water through the sulfidic mangrove sediments. In the mangrove-porewater dominated tidal creek, sulfur- and nitrogen-containing as well as aromatic DOM compounds were relatively enriched, whereas phosphorous-containing DOM was relatively depleted compared to non-mangrove fringed areas. In areas with intense mixing of estuarine and marine water masses we observed a strong decrease of these DOM compounds relative to values expected from conservative mixing, suggesting their removal by photodegradation and co-precipitation with particles such as Mn(hydr)oxides and/or as organometallic complexes, leading to more aliphatic DOM signatures at the creek-mouth. Tidally driven porewater exchange and surface water runoff from the mangroves had a stronger effect on the biogeochemical cycling in the estuary than the fluvial input during a dry compared to a wet season. Our study confirms that mangroves can significantly contribute to biogeochemical budgets of (sub)tropical estuaries

Drivers of pCO2 Variability in Two Contrasting Coral Reef Lagoons: The Influence of Submarine Groundwater Discharge

The impact of groundwater on pCO2 variability was assessed in two coral reef lagoons with distinct drivers of submarine groundwater discharge (SGD). Diel variability of pCO2 in the two ecosystems was explained by a combination of biological drivers and SGD inputs. In Rarotonga, a South Pacific volcanic island, 222Rn‐derived SGD was driven primarily by a steep terrestrial hydraulic gradient, and the water column was influenced by the high pCO2 (5501 µatm) of the fresh groundwater. In Heron Island, a Great Barrier Reef coral cay, SGD was dominated by seawater recirculation through the sediments (i.e., tidal pumping), and pCO2 was mainly impacted through the stimulation of biological processes. The Rarotonga water column had a higher average pCO2 (549 µatm) than Heron Island (471 µatm). However, pCO2 exhibited a greater diel range in Heron Island (778 µatm) than in Rarotonga (507 µatm). The Rarotonga water column received 29.0 ± 8.2 mmol free‐CO2 m−2 d−1 from SGD, while the Heron Island water column received 12.1 ± 4.2 mmol free‐CO2 m−2 d−1. Over the course of this study, both systems were sources of CO2 to the atmosphere with SGD‐derived free‐CO2 most likely contributing a large portion to the air‐sea CO2 flux. Studies measuring the carbon chemistry of coral reefs (e.g., metabolism and calcification rates) may need to consider the effects of groundwater inputs on water column carbonate chemistry. Local drivers of coral reef carbonate chemistry such as SGD may offer more approachable management solutions to mitigating the effects of ocean acidification on coral reefs

Divergent drivers of carbon dioxide and methane dynamics in an agricultural coastal floodplain: post-flood hydrological and biological drivers

Many coastal floodplains have been artificially drained for agriculture, altering hydrological connectivity and the delivery of groundwater-derived solutes including carbon dioxide (CO2) and methane (CH4) to surface waters. Here, we investigated the drivers of CO2 and CH4 within the artificial drains.of a coastal floodplain under sugarcane plantation and quantify the contribution of groundwater discharge to CO2 and CH4 dynamics over a flood event (290 mm of rainfall). High temporal resolution, in situ observations of dissolved CO2 and CH4, carbon stable isotopes of CH4 (delta C-13-CH4), and the natural groundwater tracer radon (Rn-222) allowed us to quantify. CO2, CH4 and groundwater dynamics during the rapid recession of a flood over a five day period. Extreme super-saturation of free CO2 ([CO2*]) up to 2,951 mu M (25,480% of atmospheric equilibrium) was driven by large groundwater input into the drains (maximum 87 cm day-(1)), caused by a steep hydraulic head in the adjacent water table. Groundwater input sustained between 95 and 124% of the surface [CO2*] flux during the flood recession by delivering high carbonate alkalinity groundwater (DIC = 10,533 mu M, similar to pH = 7.05) to acidic surface water (pH <4), consequently transforming all groundwater-derived DIC to [CO2*]. In contrast, groundwater was not a major direct driver of CH4 contributing only 14% of total CH4 fluxes. A progressive increase in CH4 concentrations of up to similar to 2400 nM day-(1) occurred as a combination of increased substrate availability delivered by post-flood drainage water and longer residence times, which allowed for a biogenic CH4 signal to develop. The progressive enrichment in delta C-13-CH4 values (- 70%. to-48%.) and increase in CH4 concentrations (46-2460 nM) support coupled production-oxidation, with concentrations and delta C-13 values remaining higher (2,798 nM and-47%.) than pre-flood conditions (534 nM and-55 parts per thousand) three weeks after the flood. Our findings demonstrate how separate processes can drive the aquatic CO2 and CH4 response to a flood event in a drained coastal floodplain, and the key role groundwater had in post-flood [CO2*] evasion to the atmosphere, but not CH4. (C) 2016 Elsevier B.V. All rights reserved

Sitematización de la asistencia de enfermería al paciente con síndrome de la abstinencia alcohólica en la unidad de emergencia

Este trabalho trata de uma pesquisa bibliográfica cujo objetivo foi identificar o corpo de conhecimentos essenciais para prestar assistência de enfermagem a pacientes portadores da Síndrome da Abstinência Alcoólica na unidade de Pronto Socorro. A fonte principal de dados foi a Base de Dados LILACS, usando-se expressões de pesquisa pertinentes ao tema. Para compor um corpo de conhecimentos essenciais na assistência, os resultados identificaram a necessidade de usar escalas de avaliação da síndrome, ter conhecimentos sobre as manifestações clínicas, saber as terapêuticas existentes e as respectivas intervenções. Concluiu- se que a identificação deste corpo de conhecimentos pode contribuir para dispensar-se uma assistência de enfermagem efetiva a pacientes portadores desta síndrome.This paper is a literature review that aimed to identify a body of essential nursing knowledge to assess patients withAlcoholicWithdrawal Syndrome in Emergency Units. Primary data source was LILACS database using pertinent descriptors. To compose the body of essential knowledge for nursing care, results identified a need to use assessment scales, to have knowledge about clinical manifestations, to know existing therapeutics, and its related interventions. It was concluded that the identification of this body of knowledge can contribute for an effective nursing care to patients with that syndrome.Este artículo es una investigación bibliográfica que tuvo como objetivo identificar un cuerpo esencial de conocimientos de enfermería para el cuidado de pacientes con la Síndrome de la Abstinencia Alcohólica en una unidad de emergencia. Los datos primarios fueran encontrados en la Base de Datos LILACS con el uso de descriptores pertinentes. Para la composición del cuerpo de conocimientos para la asistencia de enfermería, los resultados identificaron la necesidad del uso de escalas de evaluación, tener conocimiento acerca e las manifestaciones clínicas, conocer las terapéuticas existentes y sus respectivas intervenciones. Se concluyó que la identificación de ese cuerpo de conocimientos puede contribuir para una asistencia de enfermería efectiva a pacientes con ese síndrome

Inorganic carbon outwelling from a Mediterranean seagrass meadow using radium isotopes

Seagrass meadows are ‘blue carbon’ ecosystems widely recognised for their potential role in climate change mitigation. Previous studies have focused mainly on carbon storage within meadows and sediments. However, little is known about contribution of outwelling (i.e., lateral transport) to seagrass carbon budgets. Here, radium isotopes (223Ra and 224Ra) were used to assess dissolved inorganic carbon (DIC) and total alkalinity (TA) outwelling from a Mediterranean Posidonia oceanica meadow during early autumn. DIC outwelling was 114 ± 61 mmol m − 2 day − 1 and exceeded above-meadow CO2 outgassing (3 ± 1 mmol m − 2 day − 1). Production of DIC was uncoupled from TA and fuelled by net heterotrophy and aerobic processes within the meadow. The small export of TA (5 ± 6 mmol m−2 day − 1) implied that ∼ 90 % of outwelled DIC may return to the atmosphere as CO2 in offshore waters. Combining these fluxes with above-meadow outgassing suggested a total carbon loss that exceeded long term burial in sediments. Overall, the meadow acted as a carbon source to the atmosphere during the early autumn season. Further studies quantifying outwelling at multiple spatial and temporal scales are required to better resolve seagrass carbon budgets and their contribution to carbon sequestration