Phenotypical responses of Fucus vesiculosus germlings to warming, acidification, nutrient enrichment and local upwelling under natural fluctuations (July - September 2014)

During summer 2014 (mid-July - mid-September 2014), early life-stage Fucus vesiculosus were exposed to combined ocean acidification and warming (OAW) in the presence and absence of enhanced nutrient levels (OAW x N experiment). Subsequently, F. vesiculosus germlings were exposed to a final upwelling disturbance during 3 days (mid-September 2014). Experiments were performed in the near-natural scenario "Kiel Outdoor Benthocosms" including natural fluctuations in the southwestern Baltic Sea, Kiel Fjord, Germany (54°27 'N, 10°11 'W). Genetically different sibling groups and different levels of genetic diversity were employed to test to which extent genetic variation would result in response variation. The data presented here show the phenotypical response (growth and survival) of the different experimental populations of F. vesiculosus under OAW, nutrient enrichment and the upwelling event. Log effect ratios demonstrate the responses to enhanced OAW and nutrient concentrations relative to the ambient conditons. Carbon, nitrogen content (% DW) and C:N ratios were measured after the exposure of ambient and high nutrient levels. Abiotic conditions the OAW x nutrient experiment and the upwelling event, are shown.

Adaptation of a globally important coccolithophore to ocean warming and acidification

Regulating intracellular pH (pHi) is critical for optimising the metabolic activity of corals, yet mechanisms involved in pH regulation and the buffering capacity within coral cells are not well understood. Our study investigated how the presence of symbiotic dinoflagellates affects the response of pHi to pCO2-driven seawater acidification in cells isolated from Pocillopora damicornis. Using the fluorescent dye BCECF-AM, in conjunction with confocal microscopy, we simultaneously characterised the response of pHi in host coral cells and their dinoflagellate symbionts, in symbiotic and non-symbiotic states under saturating light, with and without the photosynthetic inhibitor DCMU. Each treatment was run under control (pH 7.8) and CO2 acidified seawater conditions (decreasing pH from 7.8 - 6.8). After two hours of CO2 addition, by which time the external pH (pHe) had declined to 6.8, the dinoflagellate symbionts had increased their pHi by 0.5 pH units above control levels. In contrast, in both symbiotic and non-symbiotic host coral cells, 15 min of CO2 addition (0.2 pH unit drop in pHe) led to cytoplasmic acidosis equivalent to 0.4 pH units. Despite further seawater acidification over the duration of the experiment, the pHi of non-symbiotic coral cells did not change, though in host cells containing a symbiont cell the pHi recovered to control levels. This recovery was negated when cells were incubated with DCMU. Our results reveal that photosynthetic activity of the endosymbiont is tightly coupled with the ability of the host cell to recover from cellular acidosis after exposure to high CO2 / low pH.

Oligocene to early Miocene benthic foraminifera in the eastern Equatorial Pacific

We investigated Oligocene and early Miocene benthic foraminiferal faunas (> 105 µm in size) from Ocean Drilling Program (Leg 199) Site 1218 (4826 m water depth and ~3300 to ~4000 m paleo-water depth) and Site 1219 (5063 m water depth and ~4200 to ~4400 m paleo-water depth) to understand the response of abyssal benthic foraminifera to mid-Oligocene glacial events in the eastern Equatorial Pacific Ocean. Two principal factor assemblages were recognized. The Factor 1 assemblage (common Nuttallides umbonifer) is related to either an influx of the Southern Component Water (SCW), possibly carbonate undersaturated, or a decrease in seasonality of the food supply from the surface ocean. The Factor 2 assemblage is characterized by typical deep-sea taxa living under variable trophic conditions, possibly with a seasonal component in food supply. The occurrence of abyssal benthic foraminifera faunas during the mid-Oligocene depends on either the effect of SCW or the seasonality of food resources. The Factor 1 assemblage was most common near 76Ol-C11r, 73Ol-C10rn and 67Ol-C9n (ca. 30.2, 29.1 and 26.8 Ma respectively by Pälike et al. (2006, doi:10.1126/science.1133822)). This indicates that the effect of SCW increased or the seasonal input of food from the surface ocean to benthic environments was weakened close to these glacial events. In contrast, the huge export flux of small biogenic carbonate particles close to these glacial events might be responsible for carbonate-rich sediments buffering carbonate undersaturation. Changes in deep-water masses or the periodicity of food supply from the surface ocean and variation in surface carbonate production affected by orbital forcing had an impact on the mid-Oligocene faunas of abyssal benthic foraminifera around the intervals of glacial events in the eastern Equatorial Pacific Ocean. The Factor 1 assemblage decreased sharply at ? 30 Ma (29.8 Ma by Pälike et al. (2006), 30.0 Ma by CK95) and returned to dominance after ? 29 Ma (28.6 Ma by Pälike et al. (2006), 28.8 Ma by CK95). It is likely that the effect of SCW (possibly carbonate undersaturated) has intensified since the late Oligocene. The faunal transition of benthic foraminifera in the eastern Equatorial Pacific Ocean at ~29 Ma might be attributable to the influence of Northern Component Water (NCW) input to the Southern Ocean and the subsequent formation of SCW at about that time.

Experiment on inter- and intra-specific phenotypic plasticity of three phytoplankton species in response to ocean acidification

Phenotypic plasticity describes the phenotypic adjustment of the same genotype to different environmental conditions and is best described by a reaction norm. We focus on the effect of ocean acidification (OA) on inter - and intraspecific reaction norms of three globally important phytoplankton species (Emiliania huxleyi, Gephyrocapsa oceanica, Chaetoceros affinis). Despite significant differences in growth rates between the species, they all showed a high potential for phenotypic buffering (no significant difference in growth rates between ambient and high CO2 condition). Only three coccolithophore genotypes showed a reduced growth in high CO2. Largely diverging responses to high CO2 of single coc-colithophore genotypes compared to the respective mean species responses, however, raise the question if an extrapolation to the population level is possible from single genotype experiments. We therefore compared the mean response of all tested genotypes to a total species response comprising the same genotypes, which was not significantly different in the coccolithophores. Assessing species reac-tion norm to different environmental conditions on short time scale in a genotype-mix could thus reduce sampling effort while increasing predictive power.

Seawater carbonate chemistry and community calcification near Lizar Island, 2011

It is predicted that surface ocean pH will reach 7.9, possibly 7.8 by the end of this century due to increased carbon dioxide (CO2) in the atmosphere and in the surface ocean. While aragonite-rich sediments don't begin to dissolve until a threshold pH of ~ 7.8 is reached, dissolution from high-Mg calcites is evident with any drop in pH. Indeed, it is high-Mg calcite that dominates the reaction of carbonate sediments with increased CO2, which undergoes a rapid neomorphism process to a more stable, low-Mg calcite. This has major implications for the future of the high-Mg calcite producing organisms within coral reef ecosystems. In order to understand any potential buffering system offered by the dissolution of carbonate sediments under a lower oceanic pH, this process of high-Mg calcite dissolution in the reef environment must be further elucidated.

Seawater carbonate chemistry and crab Necora puber size and elements in tissue during experiments, 2010

Ocean acidification (OA) is predicted to play a major role in shaping species biogeography and marine biodiversity over the next century. We tested the effect of medium-term exposure to OA (pH 8.00, 7.30 and 6.70 for 30 d) on acid-base balance in the decapod crab Necora puber-a species that is known to possess good extracellular buffering ability during short-term exposure to hypercapnic conditions. To determine if crabs undergo physiological trade-offs in order to buffer their haemolymph, we characterised a number of fundamental physiological functions, i.e. metabolic rate, tolerance to heat, carapace and chelae [Ca2+] and [Mg2+], haemolymph [Ca2+] and [Mg2+], and immune response in terms of lipid peroxidation. Necora puber was able to buffer changes to extracellular pH over 30 d exposure to hypercapnic water, with no evidence of net shell dissolution, thus demonstrating that HCO3- is actively taken up from the surrounding water. In addition, tolerance to heat, carapace mineralization, and aspects of immune response were not affected by hypercapnic conditions. In contrast, whole-animal O2uptake significantly decreased with hypercapnia, while significant increases in haemolymph [Ca2+] and [Mg2+] and chelae [Mg2+] were observed with hypercapnia. Our results confirm that most physiological functions in N. puber are resistant to low pH/hypercapnia over a longer period than previously investigated, although such resistance comes at the expenses of metabolic rates, haemolymph chemistry and chelae mineralization.

Competition for Cooperation: variability, benefits and heritability of relational wealth in hunter-gatherers

Many defining human characteristics including theory of mind, culture and language relate to our sociality, and facilitate the formation and maintenance of cooperative relationships. Therefore, deciphering the context in which our sociality evolved is invaluable in understanding what makes us unique as a species. Much work has emphasised group-level competition, such as warfare, in moulding human cooperation and sociality. However, competition and cooperation also occur within groups; and inter-individual differences in sociality have reported fitness implications in numerous non-human taxa. Here we investigate whether differential access to cooperation (relational wealth) is likely to lead to variation in fitness at the individual level among BaYaka hunter-gatherers. Using economic gift games we find that relational wealth: a) displays individual-level variation; b) provides advantages in buffering food risk, and is positively associated with body mass index (BMI) and female fertility; c) is partially heritable. These results highlight that individual-level processes may have been fundamental in the extension of human cooperation beyond small units of related individuals, and in shaping our sociality. Additionally, the findings offer insight in to trends related to human sociality found from research in other fields such as psychology and epidemiology.

The role of coccolithophore calcification in bioengineering their environment.

Coccolithophorids are enigmatic plankton that produce calcium carbonate coccoliths, which over geological time have buried atmospheric CO2 into limestone, changing both the atmosphere and geology of the Earth. However, the role of coccoliths for the proliferation of these organisms remains unclear; suggestions include roles in anti-predation, enhanced photosynthesis and sun-screening. Here we test the hypothesis that calcification stabilizes the pH of the seawater proximate to the organisms, providing a level of acidification countering the detrimental basification that occurs during net photosynthesis. Such bioengineering provides a more stable pH environment for growth and fits the empirical evidence for changes in rates of calcification under different environmental conditions. Under this scenario, simulations suggest that the optimal production ratio of inorganic to organic particulate C (PIC : POCprod) will be lower (by approx. 20%) with ocean acidification and that overproduction of coccoliths in a future acidified ocean, where pH buffering is weaker, presents a risk to calcifying cells.

The role of coccolithophore calcification in bioengineering their environment.

Coccolithophorids are enigmatic plankton that produce calcium carbonate coccoliths, which over geological time have buried atmospheric CO2 into limestone, changing both the atmosphere and geology of the Earth. However, the role of coccoliths for the proliferation of these organisms remains unclear; suggestions include roles in anti-predation, enhanced photosynthesis and sun-screening. Here we test the hypothesis that calcification stabilizes the pH of the seawater proximate to the organisms, providing a level of acidification countering the detrimental basification that occurs during net photosynthesis. Such bioengineering provides a more stable pH environment for growth and fits the empirical evidence for changes in rates of calcification under different environmental conditions. Under this scenario, simulations suggest that the optimal production ratio of inorganic to organic particulate C (PIC : POCprod) will be lower (by approx. 20%) with ocean acidification and that overproduction of coccoliths in a future acidified ocean, where pH buffering is weaker, presents a risk to calcifying cells.

Molecular basis of canalization in an ascidian species complex adapted to different thermal conditions

Canalization is a result of intrinsic developmental buffering that ensures phenotypic robustness under genetic variation and environmental perturbation. As a consequence, animal phenotypes are remarkably consistent within a species under a wide range of conditions, a property that seems contradictory to evolutionary change. Study of laboratory model species has uncovered several possible canalization mechanisms, however, we still do not understand how the level of buffering is controlled in natural populations. We exploit wild populations of the marine chordate Ciona intestinalis to show that levels of buffering are maternally inherited. Comparative transcriptomics show expression levels of genes encoding canonical chaperones such as Hsp70 and Hsp90 do not correlate with buffering. However the expression of genes encoding endoplasmic reticulum (ER) chaperones does correlate. We also show that ER chaperone genes are widely conserved amongst animals. Contrary to previous beliefs that expression level of Heat Shock Proteins (HSPs) can be used as a measurement of buffering levels, we propose that ER associated chaperones comprise a cellular basis for canalization. ER chaperones have been neglected by the fields of development, evolution and ecology, but their study will enhance understanding of both our evolutionary past and the impact of global environmental change.

Molecular basis of canalization in an ascidian species complex adapted to different thermal conditions

Canalization is a result of intrinsic developmental buffering that ensures phenotypic robustness under genetic variation and environmental perturbation. As a consequence, animal phenotypes are remarkably consistent within a species under a wide range of conditions, a property that seems contradictory to evolutionary change. Study of laboratory model species has uncovered several possible canalization mechanisms, however, we still do not understand how the level of buffering is controlled in natural populations. We exploit wild populations of the marine chordate Ciona intestinalis to show that levels of buffering are maternally inherited. Comparative transcriptomics show expression levels of genes encoding canonical chaperones such as Hsp70 and Hsp90 do not correlate with buffering. However the expression of genes encoding endoplasmic reticulum (ER) chaperones does correlate. We also show that ER chaperone genes are widely conserved amongst animals. Contrary to previous beliefs that expression level of Heat Shock Proteins (HSPs) can be used as a measurement of buffering levels, we propose that ER associated chaperones comprise a cellular basis for canalization. ER chaperones have been neglected by the fields of development, evolution and ecology, but their study will enhance understanding of both our evolutionary past and the impact of global environmental change.

Exploration du rôle modérateur des stratégies d’adaptation sur la relation entre les mauvais traitements perçus et les problèmes psychologiques d’adolescents à risque

Les adolescents qui ont subi de la négligence ou des abus substantiels dans leur famille risquent de présenter des symptômes anxieux et dépressifs et des comportements antisociaux plus importants. Parmi les ressources internes qui pourraient contribuer à la résilience de ces jeunes, les stratégies qu’ils adoptent pour composer avec les situations stressantes ont été peu examinées. Dans cette thèse, nous examinons les stratégies d’adaptation utilisées par 336 adolescents placés en centre de réadaptation, avec pour objectif de vérifier leur rôle modérateur dans la relation entre les mauvais traitements qu’ils perçoivent et l’ampleur de leurs problèmes intériorisés ou extériorisés. Le premier chapitre présente une revue de la recherche sur les liens entre divers stresseurs, les stratégies d’adaptation des jeunes et leur condition psychologique. Ces études mettent en lumière combien les effets des stratégies qu’ils utilisent peuvent varier selon les stresseurs familiaux ou sociaux auxquels ils sont exposés. Les deux études empiriques aux chapitres 2 et 3 portent sur les interactions entre trois types de maltraitance (abus émotionnel ou physique, négligence émotionnelle) et quatre stratégies d’adaptation (centrées sur les problèmes, les émotions, la diversion sociale et la distraction). Dans la première étude, ces interactions sont testées pour leurs effets sur l’ampleur des problèmes intériorisés rapportés par les jeunes ou leurs éducateurs; la seconde étude explore leurs effets sur l’ampleur des problèmes extériorisés. Quand les problèmes intériorisés sont rapportés par les adolescents, les stratégies centrées sur les problèmes, la diversion sociale et la distraction avaient un effet protecteur sur l’ampleur des symptômes associés à la maltraitance émotionnelle, surtout chez les filles. Les stratégies centrées sur les problèmes ont aussi un effet protecteur sur la relation entre l’abus émotionnel et les comportements agressifs rapportés par les jeunes. Toutefois quand il s’agit des problèmes extériorisés, plusieurs interactions montrent plutôt que les effets adaptatifs de certaines stratégies diminuent quand les mauvais traitements augmentent. Il en est ainsi pour les stratégies centrées sur les problèmes ou la diversion sociale quand ces problèmes sont observés par les éducateurs, et pour les distractions, lorsqu’ils sont rapportés par les filles. Enfin la diversion sociale est associée à des comportements délinquants plus marqués rapportés par les jeunes et son effet modérateur chez les garçons montre que cette relation est plus forte quand ils sont moins maltraités. Les stratégies d’adaptation examinées contribuent donc surtout à atténuer la détresse émotionnelle des filles victimes de maltraitance psychologique, mais elles semblent avoir peu d’impact sur les comportements antisociaux des jeunes maltraités. Ces résultats sont discutés en lien avec les caractéristiques de notre échantillon. Les implications cliniques qui s’en dégagent permettent de suggérer des pistes pour mieux soutenir ces jeunes dans l’apprentissage de stratégies adaptatives pour réguler leur stress.

Functions of the SLC36 transporter Pathetic in growth control of Drosophila sensory neurons

Thesis (Ph.D.)--University of Washington, 2016-08

Letting the managers manage: analyzing capacity to conserve biodiversity in a cross-border protected area network

Biodiversity loss is one of the most significant drivers of ecosystem change and is projected to continue at a rapid rate. While protected areas, such as national parks, are seen as important refuges for biodiversity, their effectiveness in stemming biodiversity decline has been questioned. Public agencies have a critical role in the governance of many such areas, but there are tensions between the need for these agencies to be more “adaptive” and their current operating environment. Our aim is to analyze how institutions enable or constrain capacity to conserve biodiversity in a globally significant cross-border network of protected areas, the Australian Alps. Using a novel conceptual framework for diagnosing biodiversity institutions, our research examined institutional adaptive capacity and more general capacity for conserving biodiversity. Several intertwined issues limit public agencies’ capacity to fulfill their conservation responsibilities. Narrowly defined accountability measures constrain adaptive capacity and divert attention away from addressing key biodiversity outcomes. Implications for learning were also evident, with protected area agencies demonstrating successful learning for on-ground issues but less success in applying this learning to deeper policy change. Poor capacity to buffer political and community influences in managing significant cross-border drivers of biodiversity decline signals poor fit with the institutional context and has implications for functional fit. While cooperative federalism provides potential benefits for buffering through diversity, it also means protected area agencies have restricted authority to address cross-border threats. Restrictions on staff authority and discretion, as public servants, have further implications for deploying capacity. This analysis, particularly the possibility of fostering “ambidexterity”—creatively responding to political pressures in a way that also achieves a desirable outcome for biodiversity conservation—is one promising way of building capacity to buffer both political influences and ecological pressures. The findings and the supporting analysis provide insight into how institutional capacity to conserve biodiversity can be enhanced in protected areas in Australia and elsewhere, especially those governed by public agencies and/or multiple organizations and across jurisdictions.

Intolérence à l'effort en hypertension artérielle pulmonaire : Implication des déterminants périphériques

L’hypertension artérielle pulmonaire (HTAP) est une maladie caractérisée par l’augmentation progressive des résistances vasculaires pulmonaires causant une augmentation de la pression artérielle pulmonaire qui mène au décès prématuré des patients. Malgré une amélioration rapide ces dernières années des traitements spécifiques, les patients souffrant d’HTAP demeurent dyspnéiques et intolérants à l’effort. L’atteinte vasculaire pulmonaire est actuellement irréversible. Elle est également la source de plusieurs anomalies au niveau des systèmes cardiovasculaires, ventilatoires et musculaires constituant les principaux déterminants physiologiques de la capacité à l’effort des patients. Cette thèse a investigué différentes facettes de la tolérance à l’effort en HTAP : les différents mécanismes ayant un impact sur l’apport musculaire en oxygène, l’altération des voies de signalisation cellulaire impliquées dans l’angiogenèse musculaire et les mécanismes ayant un impact sur la régulation du débit sanguin et l’oxygénation cérébrale en HTAP. Nous avons premièrement documenté une diminution de l’apport en oxygène aux muscles squelettiques à l’effort des patients en relation avec une diminution de la densité capillaire musculaire. Ce défaut d’angiogenèse corrélait d’ailleurs avec la capacité à l’effort des sujets. Par la suite, nous avons étudié les voies de signalisations cellulaires de l’angiogenèse musculaire. Ces résultats ont permis de démontrer une diminution de l’expression de miR-126, unique aux patients HTAP, qui était responsable de la diminution de la densité capillaire et qui contribuait à leur intolérance à l’effort. De plus, il était possible de moduler in vivo l’expression de miR-126. L’expérimentation in vivo, à l’aide d’un modèle murin d’HTAP, a permis de rétablir l’expression de miR-126, d’augmenter la microcirculation musculaire et d’améliorer la tolérance à l’effort des animaux, ce qui met en lumière le potentiel thérapeutique de l’angiogenèse musculaire pour améliorer la capacité à l’effort en HTAP. Notre dernier projet a démontré que les patients HTAP présentaient une diminution de débit sanguin cérébral. Ce projet a également démontré que les changements de pression artérielle sont moins bien amortis par les vaisseaux cérébraux des patients et que leurs vaisseaux cérébraux étaient moins réactifs aux changements de CO2. Les patients présentaient aussi une augmentation de la sensibilité des chémorécepteurs centraux qui contribuait à augmenter leur ventilation au repos, mais aussi à l’exercice. Finalement, à l’effort, nous avons démontré que le débit sanguin cérébral des patients HTAP était principalement influencé par la pression artérielle alors que chez les sujets sains, le débit sanguin cérébral était influencé principalement par la PETCO2. Nous avons également démontré que les patients HTAP présentaient une diminution progressive de leur oxygénation cérébrale, qui corrélait avec leur capacité à l’effort. Les résultats obtenus au cours de ce doctorat démontrent bien que la capacité à l’effort en HTAP est aussi déterminée par plusieurs anomalies physiopathologiques périphériques.