Bio-physical interactions and feedbacks in a global climate model

This PhD thesis addresses the topic of large-scale interactions between climate and marine biogeochemistry. To this end, centennial simulations are performed under present and projected future climate conditions with a coupled ocean-atmosphere model containing a complex marine biogeochemistry model. The role of marine biogeochemistry in the climate system is first investigated. Phytoplankton solar radiation absorption in the upper ocean enhances sea surface temperatures and upper ocean stratification. The associated increase in ocean latent heat losses raises atmospheric temperatures and water vapor. Atmospheric circulation is modified at tropical and extratropical latitudes with impacts on precipitation, incoming solar radiation, and ocean circulation which cause upper-ocean heat content to decrease at tropical latitudes and to increase at middle latitudes. Marine biogeochemistry is tightly related to physical climate variability, which may vary in response to internal natural dynamics or to external forcing such as anthropogenic carbon emissions. Wind changes associated with the North Atlantic Oscillation (NAO), the dominant mode of climate variability in the North Atlantic, affect ocean properties by means of momentum, heat, and freshwater fluxes. Changes in upper ocean temperature and mixing impact the spatial structure and seasonality of North Atlantic phytoplankton through light and nutrient limitations. These changes affect the capability of the North Atlantic Ocean of absorbing atmospheric CO2 and of fixing it inside sinking particulate organic matter. Low-frequency NAO phases determine a delayed response of ocean circulation, temperature and salinity, which in turn affects stratification and marine biogeochemistry. In 20th and 21st century simulations natural wind fluctuations in the North Pacific, related to the two dominant modes of atmospheric variability, affect the spatial structure and the magnitude of the phytoplankton spring bloom through changes in upper-ocean temperature and mixing. The impacts of human-induced emissions in the 21st century are generally larger than natural climate fluctuations, with the phytoplankton spring bloom starting one month earlier than in the 20th century and with ~50% lower magnitude. This PhD thesis advances the knowledge of bio-physical interactions within the global climate, highlighting the intrinsic coupling between physical climate and biosphere, and providing a framework on which future studies of Earth System change can be built on.

Recycled crustal material in the geochemical record of Pacific ocean island basalts from Pitcairn, Hawaii and Rurutu

Die Isotopenzusammensetzungen des Pitcairn Hotspot (Südpazifik), des Mauna Kea (Hawaii) und der Insel Rurutu (Französisch Polynesien) wurden bestimmt, um Heterogenitäten im Erdmantel zu charakterisieren. Die Bleiisotopenzusammensetzung wurde mit einer Dreiisotopenspiketechnik zur Korrektur der instrumentellen Massenfraktionierung gemessen. An Proben von Pitcairn wurde zusätzlich die Os, Hf, Nd, Sr Isotopenzusammensetzung, sowie die Haupt- und Spurenelementzusammensetzung bestimmt. Die Isotopensignatur des Pitcairn Hotspots kann durch eine Sedimentkomponente in der Magmenquelle erklärt werden. Die Bleiisotopenschwankungen des Mauna Kea in der HSDP-2 Bohrung treten als Oszillationen auf, die sich zu linearen Anordnungen im Bleiisotopenraum zusammensetzen. Das begrenzte zeitliche Auftreten einer linearen Anordnung zeigt, daß die Heterogenitäten mehrere zehner Kilometer Länge im aufsteigenden Mantelmaterial unter dem Vulkan einnehmen. Auch die Bleiisotopenzusammensetzungen der Rurutu-laven zeigen lineare Anordnungen.Diese lineare Anordnungen im Bleiisotopenraum können durch eine vorwiegend binäre Mischung erklärt werden. Ein Bleiisotopenentwicklungsmodell unterstützt, daß die Differenzierung der Ausgangsmaterialien vor weniger als etwa zwei Milliarden Jahren geschah und für Mauna Kea relativ jung sein könnte. Keine der Hotspots weisen identische Mischungsendglieder auf, so daß die Heterogenitäten kleinräumige Merkmale im Erdmantel sind.

El Niño southern oscillation and its effect on fog oases along the Peruvian and Chilean coastal deserts

Fog oases, locally named Lomas, are distributed in a fragmented way along the western coast of Chile and Peru (South America) between ~6°S and 30°S following an altitudinal gradient determined by a fog layer. This fragmentation has been attributed to the hyper aridity of the desert. However, periodically climatic events influence the ‘normal seasonality’ of this ecosystem through a higher than average water input that triggers plant responses (e.g. primary productivity and phenology). The impact of the climatic oscillation may vary according to the season (wet/dry). This thesis evaluates the potential effect of climate oscillations, such as El Niño Southern Oscillation (ENSO), through the analysis of vegetation of this ecosystem following different approaches: Chapters two and three show the analysis of fog oasis along the Peruvian and Chilean deserts. The objectives are: 1) to explain the floristic connection of fog oases analysing their taxa composition differences and the phylogenetic affinities among them, 2) to explore the climate variables related to ENSO which likely affect fog production, and the responses of Lomas vegetation (composition, productivity, distribution) to climate patterns during ENSO events. Chapters four and five describe a fog-oasis in southern Peru during the 2008-2010 period. The objectives are: 3) to describe and create a new vegetation map of the Lomas vegetation using remote sensing analysis supported by field survey data, and 4) to identify the vegetation change during the dry season. The first part of our results show that: 1) there are three significantly different groups of Lomas (Northern Peru, Southern Peru, and Chile) with a significant phylogenetic divergence among them. The species composition reveals a latitudinal gradient of plant assemblages. The species origin, growth-forms typologies, and geographic position also reinforce the differences among groups. 2) Contradictory results have emerged from studies of low-cloud anomalies and the fog-collection during El Niño (EN). EN increases water availability in fog oases when fog should be less frequent due to the reduction of low-clouds amount and stratocumulus. Because a minor role of fog during EN is expected, it is likely that measurements of fog-water collection during EN are considering drizzle and fog at the same time. Although recent studies on fog oases have shown some relationship with the ENSO, responses of vegetation have been largely based on descriptive data, the absence of large temporal records limit the establishment of a direct relationship with climatic oscillations. The second part of the results show that: 3) five different classes of different spectral values correspond to the main land cover of Lomas using a Vegetation Index (VI). The study case is characterised by shrubs and trees with variable cover (dense, semi-dense and open). A secondary area is covered by small shrubs where the dominant tree species is not present. The cacti area and the old terraces with open vegetation were not identified with the VI. Agriculture is present in the area. Finally, 4) contrary to the dry season of 2008 and 2009 years, a higher VI was obtained during the dry season of 2010. The VI increased up to three times their average value, showing a clear spectral signal change, which coincided with the ENSO event of that period.

Measurement of the oscillation frequency of B s mesons in the hadronic decay mode B s pi D s (phi pi) X with the D0 detector at the Fermilab Tevatron collider

The standard model (SM) of particle physics is a theory, describing three out of four fundamental forces. In this model the Cabibbo-Kobayashi-Maskawa (CKM) matrix describes the transformation between the mass and weak eigenstates of quarks. The matrix properties can be visualized as triangles in the complex plane. A precise measurement of all triangle parameters can be used to verify the validity of the SM. The least precisely measured parameter of the triangle is related to the CKM element |Vtd|, accessible through the mixing frequency (oscillation) of neutral B mesons, where mixing is the transition of a neutral meson into its anti-particle and vice versa. It is possible to calculate the CKM element |Vtd| and a related element |Vts| by measuring the mass differences Dmd (Dms ) between neutral Bd and bar{Bd} (Bs and bar{Bs}) meson mass eigenstates. This measurement is accomplished by tagging the initial and final state of decaying B mesons and determining their lifetime. Currently the Fermilab Tevatron Collider (providing pbar{p} collisions at sqrt{s}=1.96 TeV) is the only place, where Bs oscillations can be studied. The first selection of the "golden", fully hadronic decay mode Bs->Ds pi(phi pi)X at DØ is presented in this thesis. All data, taken between April 2002 and August 2007 with the DØ detector, corresponding to an integrated luminosity of int{L}dt=2.8/fb is used. The oscillation frequency Dms and the ratio |Vtd|/|Vts| are determined as Dms = (16.6 +0.5-0.4(stat) +0.4-0.3(sys)) 1/ps, |Vtd|/|Vts| = 0.213 +0.004-0.003(exp)pm 0.008(theor). These results are consistent with the standard model expectations and no evidence for new physics is observable.

Are there genetic breaks between Atlantic and Pacific Yellowfin tuna (Thunnus albacares) populations? A preliminary study based on microsatellites gene variation

Yellowfin tuna (Thunnus albacares, YFT, Bonnaterre 1788) is one of the most important market tuna species in the world. The high mortality of juveniles is in part caused by their bycatch. Indeed, if unregulated, it could permanently destabilize stocks health. For this reason investigating and better knowing the stock boundaries represent a crucial concern. Aim of this thesis was to preliminary investigate the YFT population structure within and between Atlantic and Pacific Oceans through the analysis of genetic variation at eight microsatellite loci and assess the occurrence of barriers to the gene flow between Oceans. For this propouse we collected 4 geographical samples coming from Atlantic and Pacific Ocean and selected a panel of 8 microsatellites loci developped by Antoni et al., (2014). Samples 71-2-Y and 77-2-Y, came from rispectively west central pacific ocean (WCPO) and east central pacific ocean (ECPO), instead samples 41-1-Y and 34-2-Y derive from west central atlantic ocean (WCAO) and east central atlantic ocean (ECAO). Total 160 specimens were analyzed (40 per sample) and were carried out several genetic information as allele frequencies, allele number, allelic richness, HWE (using He and Ho) and pairwise Fst genetic distance. Results obtained, may support the panmictic theory of this species, only one of pairwise Fst obtained is statistically significant (Fst= 0.00927; pV= 0.00218) between 41-1-Y and 71-2-Y samples. Results suggest low genetic differentiation and consequent high level of gene flow between Atlantic and Pacific populations. Furthermore, we performed an analysis of molecular taxonomy through the use of ATCO (the flaking region between ATPse6 and cytochrome oxidase subunit III genes mt DNA, to discriminate within the gener Thunnus two of the related species (Yellofin and bigeye tuna) according with their difficult recognition at certain size (<40 cm). ATCO analysis in this thesis, has provided strong discriminate evidence between the target species proving to be one of the most reliable genetic tools capable to indagate within the genus Thunnus. Thus, our study has provided useful information for possible use of this protocol for conservation plans and management of this fish stocks.

Assessment of the resilience of coral reefs to natural and human disturbances by means of recruitment panels in Indo-Pacific

Indo-Pacific region encompasses about 75% of world's coral reefs, but hard coral cover in this region experienced a 32% region-wide decline since 1970s. This great change is primarily ascribable to natural and anthropogenic pressures, including climate change and human activities effects. Coral reef conservation requires management strategies oriented to maintain their diversity and the capacity to provide ecosystem goods and services. Coral reef resilience, i.e. the capacity to recover after disturbances, is critical to their long-term persistence. The aims of the present study were to design and to test field experiments intended to measure changes in recruitment processes, as a fundamental aspect of the coral reef resilience. Recruitment experiments, using artificial panels suspended in the water column, were carried out in two Indo-Pacific locations affected by different disturbances: a new mine in Bangka Island (Indonesia), and the increased sedimentation due to coastal dynamics in Vavvaru Island (Maldives). One (or more) putatively disturbed site(s) was selected to be tested against 3 randomly selected control sites. Panels’ arrangement simulates 2 proximities to living corals, i.e. the sources of propagules: few centimetres and 2 meters over. Panels were deployed simultaneously at each site and left submerged for about five months. Recruits were identified to the lowest possible taxonomic level and recruited assemblages were analysed in terms of percent cover. In general it was not possible to detect significant differences between the benthic assemblages recruited in disturbed and control sites. The high variability observed in recruits assemblages structure among control sites may be so large to mask the possible disturbance effects. Only few taxa showed possible effects of the disturb they undergo. The field tests have highlighted strengths and weaknesses of the proposed approach and, based on these results, some possible improvements were suggested.

Pacific States National Print Biennial, University of Hawaii, Hilo

Pacific States National Print Biennial University of Hawaii, Hilo Dec 2012-April 2013

UV Responses in Native Hawaiians or Other Pacific Islanders and Asians Residing in Hawaiʻi and in Maryland

Background: UV exposure causes a wide range of skin damage including cutaneous melanoma. The mechanisms of cellular and molecular damage as well as erythemal and pigmentation responses to UV exposure have largely been studied in the White population. Methods: This study systematically investigates responses to UV exposure in the Native Hawaiian and Pacific Islanders (NHPI) and Asian populations living in Hawai’i (A/HI) as well as in Asians living in Maryland (A/MD). Results: Our analyses indicate that the NHPI population is less sensitive to UV exposure than the A/HI population. Comparisons between the two Asian groups suggest that, despite slightly but not statistically different baseline constitutive pigmentation (pre-UV exposure), the A/HI and A/MD had similar UV sensitivity, measured as minimal erythemal dose (MED). However, the A/MD population had higher levels of oxy-hemoglobin at doses of 2.0, 2.8 and 4.0 MED. Unexpectedly the A/MD subjects retained higher levels of pigmentation 2 weeks post UV exposure. Conclusion: This study provides insight into UV responses of the inhabitants of Hawai’i and shows that such responses are statistically significant for relatively small samples of Native Hawaiian and Pacific Islanders, and for Asians living in Hawai’i and Asians living in Maryland.

Sensitivity of atmospheric CO2 and climate to explosive volcanic eruptions

Impacts of low-latitude, explosive volcanic eruptions on climate and the carbon cycle are quantified by forcing a comprehensive, fully coupled carbon cycle-climate model with pulse-like stratospheric aerosol optical depth changes. The model represents the radiative and dynamical response of the climate system to volcanic eruptions and simulates a decrease of global and regional atmospheric surface temperature, regionally distinct changes in precipitation, a positive phase of the North Atlantic Oscillation, and a decrease in atmospheric CO2 after volcanic eruptions. The volcanic-induced cooling reduces overturning rates in tropical soils, which dominates over reduced litter input due to soil moisture decrease, resulting in higher land carbon inventories for several decades. The perturbation in the ocean carbon inventory changes sign from an initial weak carbon sink to a carbon source. Positive carbon and negative temperature anomalies in subsurface waters last up to several decades. The multi-decadal decrease in atmospheric CO2 yields a small additional radiative forcing that amplifies the cooling and perturbs the Earth System on longer time scales than the atmospheric residence time of volcanic aerosols. In addition, century-scale global warming simulations with and without volcanic eruptions over the historical period show that the ocean integrates volcanic radiative cooling and responds for different physical and biogeochemical parameters such as steric sea level or dissolved oxygen. Results from a suite of sensitivity simulations with different magnitudes of stratospheric aerosol optical depth changes and from global warming simulations show that the carbon cycle-climate sensitivity γ, expressed as change in atmospheric CO2 per unit change in global mean surface temperature, depends on the magnitude and temporal evolution of the perturbation, and time scale of interest. On decadal time scales, modeled γ is several times larger for a Pinatubo-like eruption than for the industrial period and for a high emission, 21st century scenario.