Ana Paula Oliveira

Painted goby larvae under high-CO2 fail to recognize reef sounds

Atmospheric CO2 levels have been increasing at an unprecedented rate due to anthropogenic activity. Consequently, ocean pCO2 is increasing and pH decreasing, affecting marine life, including fish. For many coastal marine fishes, selection of the adult habitat occurs at the end of the pelagic larval phase. Fish larvae use a range of sensory cues, including sound, for locating settlement habitat. This study tested the effect of elevated CO2 on the ability of settlement-stage temperate fish to use auditory cues from adult coastal reef habitats. Wild late larval stages of painted goby (Pomatoschistus pictus) were exposed to control pCO2 (532 μatm, pH 8.06) and high pCO2 (1503 μatm, pH 7.66) conditions, likely to occur in nearshore regions subjected to upwelling events by the end of the century, and tested in an auditory choice chamber for their preference or avoidance to nighttime reef recordings. Fish reared in control pCO2 conditions discriminated reef soundscapes and were attracted by reef recordings. This behaviour changed in fish reared in the high CO2 conditions, with settlement-stage larvae strongly avoiding reef recordings. This study provides evidence that ocean acidification might affect the auditory responses of larval stages of temperate reef fish species, with potentially significant impacts on their survival.

Effects of ocean acidification on the swimming ability, development and biochemical responses of sand smelt larvae.

Ocean acidification, recognized as a major threat to marine ecosystems, has developed into one of the fastest growing fields of research in marine sciences. Several studies on fish larval stages point to abnormal behaviours, malformations and increased mortality rates as a result of exposure to increased levels of CO2. However, other studies fail to recognize any consequence, suggesting species-specific sensitivity to increased levels of CO2, highlighting the need of further research. In this study we investigated the effects of exposure to elevated pCO2 on behaviour, development, oxidative stress and energy metabolism of sand smelt larvae, Atherina presbyter. Larvae were caught at Arrábida Marine Park (Portugal) and exposed to different pCO2 levels (control: ~600μatm, pH=8.03; medium: ~1000μatm, pH=7.85; high: ~1800μatm, pH=7.64) up to 15days, after which critical swimming speed (Ucrit), morphometric traits and biochemical biomarkers were determined. Measured biomarkers were related with: 1) oxidative stress - superoxide dismutase and catalase enzyme activities, levels of lipid peroxidation and DNA damage, and levels of superoxide anion production; 2) energy metabolism - total carbohydrate levels, electron transport system activity, lactate dehydrogenase and isocitrate dehydrogenase enzyme activities. Swimming speed was not affected by treatment, but exposure to increasing levels of pCO2 leads to higher energetic costs and morphometric changes, with larger larvae in high pCO2 treatment and smaller larvae in medium pCO2 treatment. The efficient antioxidant response capacity and increase in energetic metabolism only registered at the medium pCO2 treatment may indicate that at higher pCO2 levels the capacity of larvae to restore their internal balance can be impaired. Our findings illustrate the need of using multiple approaches to explore the consequences of future pCO2 levels on organisms.

Iberia Coastal Ocean in the CO2 Sink/Source Context: Portugal Case Study

Abstract OLIVEIRA, A.P.; CABEÇADAS, G., and PILAR-FONSECA, T., 2012. Iberia coastal ocean in the CO2 sink/source context: Portugal case study. Carbon fluxes were calculated for the Portuguese western inner continental shelf region (adjacent waters off Douro, Tagus, and Sado estuaries, and Tagus estuary) and the southern outer shelf (Algarve). The role played by the described ecosystems in terms of CO2 source/sink functioning is compared with other coastal Atlantic systems off the Iberian Peninsula. Overall, the Portuguese western near-shore ecosystems emit 0.3 Tg C yr−1 to the atmosphere, which corresponds to an additional source of approximately 0.1% to the CO2 emissions of worldwide near-shore ecosystems. In these systems the CO2 water–air fluxes varied temporal and spatially. From 1999 to 2007, a trend of decreasing fluxes was observed. While annually the Iberia continental shelf is a sink for atmospheric CO2, roughly at a rate between −2.9 and −0.2 mol C m−2 yr−1, the Iberia near-shore ecosystems are sources of CO2 to the atmosphere, displaying fluxes from 0.01 to 76 mol C m−2 yr−1. An insight into the controlling factors and mechanisms for the CO2 flux variability for the distinct coastal ecosystem is provided. The Portuguese water–air CO2 fluxes presented in this work are a contribution to the European CO2 budgets.

Surgical and Non-Surgical Procedures Associated with Recurrence of Periodontitis in Periodontal Maintenance Therapy: 5-Year Prospective Study.

Background and Objective Prospective studies that investigated the influence of surgical and nonsurgical procedures in the recurrence of periodontitis and tooth loss in periodontal maintenance therapy (PMT) programs have not been previously reported. The objective of this study was to evaluate longitudinally the recurrence of periodontitis in regular compliers (RC) and irregular compliers (IC) individuals undergoing surgical and non-surgical procedures over 5 years in a program of PMT. Materials and Methods A total of 212 individuals participated in this study. Full-mouth periodontal examination including bleeding on probing, probing depth, and clinical attachment level were determined at all PMT visits over 5 years. The recurrence of periodontitis was evaluated in RC and IC individuals undergoing surgical and non-surgical procedures in PMT. The influences of risk variables of interest were tested through univariate analysis and multivariate logistic regression. Results Recurrence of periodontitis was significantly lower among RC when compared to IC. Individuals with recurrence of periodontitis and undergoing surgical procedures showed higher probing depth and clinical attachment loss than those who received non-surgical procedures. Recurrence of periodontitis was higher in individual undergoing surgical procedures and irregular compliance during PMT. Conclusions Irregular compliance and surgical procedures in individuals undergoing PMT presented higher rates of recurrence of periodontitis when compared to regular compliant patients undergoing non-surgical procedures.

Water-air CO2 fluxes in the Tagus estuary plume (Portugal) during two distinct winter episodes

BackgroundEstuarine plumes are frequently under strong influence of land-derived inputs of organic matter. These plumes have characteristic physical and chemical conditions, and their morphology and extent in the coastal area depends strongly on physical conditions such as river discharge, tides and wind action. In this work we investigate the physical dynamics of the Tagus estuary plume and the CO2 system response during two contrasting hydrological winter periods. A hydrodynamic model was used to simulate the circulation regime of the study area, thus providing relevant information on hydrodynamic processes controlling the plume.ResultsModel simulations show that for the studied periods, the major cause of the plume variability (size and shape) was the interaction between Tagus River discharge and wind. The freshwater intrusion on Tagus shelf exerted considerable influence on biochemical dynamics, allowing identification of two regions: a high nutrient region enriched in CO2 inside the estuarine plume and another warmer region rich in phytoplankton in the outer plume.ConclusionsThe Tagus estuarine plume behaved as a weak source of CO2 to the atmosphere, with estimated fluxes of 3.5u2009±u20093.7 and 27.0u2009±u20093.8xa0mmol C m−2 d−1 for February 2004 and March 2001, respectively.

Inorganic carbon distribution and CO 2 fluxes in a large European estuary (Tagus, Portugal)

Ten field cruises were carried out in Tagus estuary from 1999 to 2007 to study the dynamics of the inorganic carbon system. Dissolved inorganic carbon (DIC) and total alkalinity (TA) increased with salinity. DIC and TA were generally conservative in the estuarine mixing zone (salinityu2009>u200910), while a complex distribution pattern was observed at the upper estuary. DIC values peaked 1786.9u2009±u2009155.8 µmol kg−1 at that segment. Estimated annual mean fluxes of DIC were 0.27 Tg C yr−1 from the river to the estuary, and 0.37 Tg C yr−1 from here to the coastal area. The Tagus estuary was always CO2 supersaturated, with partial pressure of CO2 (pCO2) reaching 9160 µatm in the upper estuary. An average emission of 0.11 Tg C yr−1 was estimated from the estuary to the atmosphere, corresponding to 23% of exported DIC. Only 8% of the riverine DIC was ventilated. The non-conservative behaviour of CO2 parameters in the estuary segment under freshwater influence was attributed to alternations in the relevance of riverine/terrestrial runoff, photosynthesis, aerobic respiration, organic matter mineralization and CaCO3 precipitation/dissolution.

Effects of high pCO2 on early life development of pelagic spawning marine fish

The present study investigated the effect of elevated pCO2 on the development of early stages of the pelagic spawning marine fish Solea senegalensis, Diplodus sargus and Argyrosomus regius. Eggs and larvae were reared under control (pH 8.0, ~570μatm) and two elevated pCO2 conditions (pH 7.8, ~1100μatm; pH 7.6, ~1900μatm) until mouth opening (3 days post-hatching). Egg size did not change with exposure to elevated pCO2, but hatching rate was significantly reduced under high pCO2 for all three species. Survival rate was not affected by exposure to increased pCO2, but growth rate was differently affected across species, with A. regius growing faster in the mid-level pCO2 treatment compared with control conditions. S. senegalensis and A. regius hatched with smaller yolk sacs under increased pCO2 but endogenous reserves of D. sargus were not affected. Otoliths were consistently larger under elevated pCO2 conditions for all the three species. Differences among egg batches and a significant interaction between batch and pCO2 suggest that other factors, such as egg quality, can influence the response to increased pCO2. Overall, the results support the occurrence of a species-specific response to pCO2, but highlight the need for cautious analysis of potential sensitivity of species from unreplicated observations.

Aspects of Phytoplankton Communities Response to Climate Changes

Climate changes concerning shifts in seasonal dominant winds and increases in atmospheric CO2 are underway. Thus, changes are occurring in coastal upwelling regimes as well as increases in CO2 absorption by the ocean/acidification impacting phytoplankton communities in terms of abundance and diversity. In order to illustrate these apparent changes we present results obtained from coastal waters adjacent to the Tagus estuary under different hydrological conditions. Upwelling events prevailed in winter 1994, were absent in winter 2001 and were present in summer 2002. Chemical and biological properties are examined: in March 1994, a strong bloom of phytoplankton developed (chlorophyll a up to 40 mg m–3) which was attributed to the combined effect of intense freshwater runoff and upwelling, leading to the establishment of a strong frontal boundary and a supply of a considerable amount of nutrients. In March 2001, under an extremely intense river discharge and absence of upwelling, only values up to 1.5 mg m–3 of chlorophyll a were measured. On the other hand, in June 2002, when Tagus river inflow was reduced and nutrient levels were quite low, chlorophyll a levels attained 5 mg m–3 despite the occurrence of upwelling.