Seawater carbonate chemistry and Gadus morhua length, weight and sperm biological processes, 2010

Ocean acidification, as a consequence of increasing marine pCO2, may have severe effects on the physiology of marine organisms. However, experimental studies remain scarce, in particular concerning fish. While adults will most likely remain relatively unaffected by changes in seawater pH, early life-history stages are potentially more sensitive - particularly the critical stage of fertilization, in which sperm motility plays a central role. In this study, the effects of ocean acidification (decrease of pHT to 7.55) on sperm motility of Baltic cod, Gadus morhua, were assessed. We found no significant effect of decreased pH on sperm speed, rate of change of direction or percent motility for the population of cod analyzed. We predict that future ocean acidification will probably not pose a problem for sperm behavior, and hence fertilization success, of Baltic cod.

Seawater carbonate chemistry and biological processes during experiments with oyster Crassostrea gigas, 2009

An increasing number of studies are now reporting the effects of ocean acidification on a broad range of marine species, processes and systems. Many of these are investigating the sensitive early life-history stages that several major reviews have highlighted as being potentially most susceptible to ocean acidification. Nonetheless there remain few investigations of the effects of ocean acidification on the very earliest, and critical, process of fertilization, and still fewer that have investigated levels of ocean acidification relevant for the coming century. Here we report the effects of near-future levels of ocean acidification (?0.35 pH unit change) on sperm swimming speed, sperm motility, and fertilization kinetics in a population of the Pacific oyster Crassostrea gigas from western Sweden. We found no significant effect of ocean acidification - a result that was well-supported by power analysis. Similar findings from Japan suggest that this may be a globally robust result, and we emphasise the need for experiments on multiple populations from throughout a species' range. We also discuss the importance of sound experimental design and power analysis in meaningful interpretation of non-significant results.

Seawater carbonate chemistry, calcification and shell size of hard clam Mercenaria mercenaria during experiments, 2011

Increasing atmospheric carbon dioxide threatens to decrease pH in the world's oceans. Coastal and estuarine calcifying organisms of significant ecological and economical importance are at risk; however, several biogeochemical processes drive pH in these habitats. In particular, coastal and estuarine sediments are frequently undersaturated with respect to calcium carbonate due to high rates of organic matter remineralization, even when overlying waters are saturated. As a result, the post-larval stages of infaunal marine bivalves must be able to deposit new shell material in conditions that are corrosive to shell. We measured calcification rates on the hard clam, Mercenaria spp.,in 5 post-larval size classes (0.39, 0.56, 0.78, 0.98, and 2.90 mm shell height) using the alkalinity anomaly method. Acidity of experimental water was controlled by bubbling with air-CO2 blends to obtain pH values of 8.02, 7.64, and 7.41, corresponding to pCO2 values of 424, 1120, and 1950 µatm. These pH values are typical of those found in many near-shore terrigenous marine sediments. Our results show that calcification rate decreased with lower pH in all 5 size classes measured. We also found a significant effect of size on calcification rate, with the smaller post-larval sizes unable to overcome dissolution pressure. Increased calcification rate with size allowed the larger sizes to overcome dissolution pressure and deposit new shell material under corrosive conditions. Size dependency of pH effects on calcification is likely due to organogenesis and developmental shifts in shell mineralogy occurring through the post-larval stage. Furthermore, we found significantly different calcification rates between the 2 sources of hard clams we used for these experiments, most likely due to genotypic differences. Our findings confirm the susceptibility of the early life stages of this important bivalve to decreasing pH and reveal mechanisms behind the increased mortality in post-larval juvenile hard clams related to dissolution pressure, that has been found in previous studies.

Seawater carbonate chemistry and elemental composition of purple sea urchin (Strongylocentrotus purpuratus) calcite in a laboratory experiment

Ocean acidification will likely have negative impacts on invertebrates producing skeletons composed of calcium carbonate. Skeletal solubility is partly controlled by the incorporation of "foreign" ions (e.g. magnesium) into the crystal lattice of these skeletal structures, a process that is sensitive to a variety of biological and environmental factors. Here we explore effects of life stage, oceanographic region of origin, and changes in the partial pressure of carbon dioxide in seawater (pCO2) on trace elemental composition in the purple sea urchin (Strongylocentrotus purpuratus). We show that, similar to other urchin taxa, adult purple sea urchins have the ability to precipitate skeleton composed of a range of biominerals spanning low- to high-Mg calcites. Mg / Ca and Sr / Ca ratios were substantially lower in adult spines compared to adult tests. On the other hand, trace elemental composition was invariant among adults collected from four oceanographically distinct regions spanning a range of carbonate chemistry conditions (Oregon, Northern California, Central California, and Southern California). Skeletons of newly settled juvenile urchins that originated from adults from the four regions exhibited intermediate Mg / Ca and Sr / Ca between adult spine and test endmembers, indicating that skeleton precipitated during early life stages is more soluble than adult spines and less soluble than adult tests. Mean skeletal Mg / Ca or Sr / Ca of juvenile skeleton did not vary with source region when larvae were reared under present-day, global-average seawater carbonate conditions (400 µatm; pHT = 8.02 ± 0.03 1 SD; Omega calcite = 3.3 ± 0.2 1 SD). However, when reared under elevated pCO2 (900 µatm; pHT = 7.73 ± 0.03; Omega calcite = 1.8 ± 0.1), skeletal Sr / Ca in juveniles exhibited increased variance across the four regions. Although larvae from the northern populations (Oregon, Northern California, Central California) did not exhibit differences in Mg or Sr incorporation under elevated pCO2 (Sr / Ca = 2.10 ± 0.06 mmol/mol; Mg / Ca = 67.4 ± 3.9 mmol/mol), juveniles of Southern California origin partitioned ~8% more Sr into their skeletons when exposed to higher pCO2 (Sr / Ca = 2.26 ± 0.08 vs. 2.09 ± 0.005 mmol/mol 1 SD). Together these results suggest that the diversity of carbonate minerologies present across different skeletal structures and life stages in purple sea urchins does not translate into an equivalent geochemical plasticity of response associated with geographic variation or temporal shifts in seawater properties. Rather, composition of S. purpuratus skeleton precipitated during both early and adult life history stages appears relatively robust to spatial gradients and predicted future changes in carbonate chemistry. An exception to this trend may arise during early life stages, where certain populations of purple sea urchins may alter skeletal mineral precipitation rates and composition beyond a given pCO2 threshold. This potential for geochemical plasticity during early development in contrast to adult stage geochemical resilience adds to the growing body of evidence that ocean acidification can have differing effects across organismal life stages.

Seawater carbonate chemistry and trace element accumulation during experiments with common cuttlefish, Sepia officinalis, 2009

Cephalopods play a key role in many marine trophic networks and constitute alternative fisheries resources, especially given the ongoing decline in finfish stocks. Along the European coast, the eggs of the cuttlefish Sepia officinalis are characterized by an increasing permeability of the eggshell during development, which leads to selective accumulation of essential and non-essential elements in the embryo. Temperature and pH are two critical factors that affect the metabolism of marine organisms in the coastal shallow waters. In this study, we investigated the effects of pH and temperature through a crossed (3?2; pH 8.1 (pCO2, 400 ppm), 7.85 (900 ppm) and 7.6 (1400 ppm) at 16 and 19°C, respectively) laboratory experiment. Seawater pH showed a strong effect on the egg weight and non-significant impact on the weight of hatchlings at the end of development implying an egg swelling process and embryo growth disturbances. The lower the seawater pH, the more 110 mAg was accumulated in the tissues of hatchlings. The 109Cd concentration factor (CF) decreased with decreasing pH and 65Zn CF reached maximal values pH 7.85, independently of temperature. Our results suggest that pH and temperature affected both the permeability properties of the eggshell and embryonic metabolism. To the best of our knowledge, this is one of the first studies on the consequences of ocean acidification and ocean warming on metal uptake in marine organisms, and our results indicate the need to further evaluate the likely ecotoxicological impact of the global change on the early-life stages of the cuttlefish.

Calcification repsonse of m,arione bivalves to changed carbonate chemistry

Bivalve calcification, particularly of the early larval stages, is highly sensitive to the change in ocean carbonate chemistry resulting from atmospheric CO2 uptake. Earlier studies suggested that declining seawater [CO32-] and thereby lowered carbonate saturation affect shell production. However, disturbances of physiological processes such as acid-base regulation by adverse seawater pCO2 and pH can affect calcification in a secondary fashion. In order to determine the exact carbonate system component by which growth and calcification are affected it is necessary to utilize more complex carbonate chemistry manipulations. As single factors, pCO2 had no effects and [HCO3-] and pH had only limited effects on shell growth, while lowered [CO32-] strongly impacted calcification. Dissolved inorganic carbon (CT) limiting conditions led to strong reductions in calcification, despite high [CO32-], indicating that [HCO3-] rather than [CO32-] is the inorganic carbon source utilized for calcification by mytilid mussels. However, as the ratio [HCO3-] / [H+] is linearly correlated with [CO32-] it is not possible to differentiate between these under natural seawater conditions. An equivalent of about 80 µmol kg-1 [CO32-] is required to saturate inorganic carbon supply for calcification in bivalves. Below this threshold biomineralization rates rapidly decline. A comparison of literature data available for larvae and juvenile mussels and oysters originating from habitats differing substantially with respect to prevailing carbonate chemistry conditions revealed similar response curves. This suggests that the mechanisms which determine sensitivity of calcification in this group are highly conserved. The higher sensitivity of larval calcification seems to primarily result from the much higher relative calcification rates in early life stages. In order to reveal and understand the mechanisms that limit or facilitate adaptation to future ocean acidification, it is necessary to better understand the physiological processes and their underlying genetics that govern inorganic carbon assimilation for calcification.

Laboratory Investigation of Diluted Bitumen Trapping and Dissolution in Gravel

The Canadian economy is largely dependent on the distribution of large volumes of oil to domestic and international markets by a long network of pipelines. Unfortunately, accidents occur, and oil can leak or spill from these pipelines before it reaches its destination. Of particular concern are the long-term consequences of oil spills in freshwater, which include sinking of oil in water and the contamination of sensitive areas, such as where fish (e.g., salmon) deposit their eggs in gravel-dominated river sediments. There is a knowledge gap regarding the fate and behaviour of oil in river sediment. To this end, this study aimed at finding the potential for diluted bitumen (dilbit) oil to become trapped in gravel and to transfer hydrocarbons into water by dissolution, which are harmful to aquatic life. Two sets of laboratory experiments were conducted to simulate conditions of an oil spill on an exposed bank or in shallow water. In the first set, by conducting capillary pressure-saturation (Pc-Sw) experiments it was found that dilbit can enter gravel pores without much resistance and approximately 14% of the pore volume can be occupied by discontinuous single or multipore blobs of dilbit following imbibition of water. Air-water Pc-Sw experiments done in laboratory 1-D columns required gravity correction and could be successfully scaled to predict dilbit-water Pc-Sw curves, except for the trapped amount of dilbit. Trapped dilbit constituents can be dissolved into the water flowing through gravel pores (hyporheic flow) at different velocities. In the second set, dissolution experiments suggested that for the duration of the test, hydrocarbons that cause acute toxicity dissolve rapidly, likely resulting in a decrease in their effective solubility. However, dilbit saturation changed only <2% within that time. Chronically toxic PAH compounds were also detected in the effluent water. The total concentration of all detected PAHs and alkylPAHs exceeded the threshold literature value to protect early-life stage fish. Observations of decreased concentrations with increased aqueous velocities as well as less than equilibrium concentrations indicated that the mass transfer was rate-limited. A correlation was developed for the mass transfer rate coefficient to understand the mass transfer behaviour beyond the conditions used in the experiments, which had a Reynolds number exponent similar to the studies of NAPL dissolution in groundwater.

Progress and the Lack of Progress in Addressing Infant Health and Infant Health Inequalities in Ireland during the 20th Century

There is a growing literature which documents the importance of early life environment for outcomes across the life cycle. Research, including studies based on Irish data, demonstrates that those who experience better childhood conditions go on to be wealthier and healthier adults. Therefore, inequalities at birth and in childhood shape inequality in wellbeing in later life, and the historical evolution of the mortality and morbidity of children born in Ireland is important for understanding the current status of the Irish population. In this paper, I describe these patterns by reviewing the existing literature on infant health in Ireland over the course of the 20th century. Up to the 1950s, infant mortality in Ireland (both North and South) was substantially higher than in other developed countries, with a large penalty for those born in urban areas. The subsequent reduction in this penalty, and the sustained decline in infant death rates, occurred later than would be expected from the experience in other contexts. Using records from the Rotunda Lying-in Hospital in Dublin, I discuss sources of disparities in stillbirth in the early 1900s. Despite impressive improvements in death rates since that time, a comparison with those born at the end of the century reveals that Irish children continue to be born unequal. Evidence from studies which track people across the life course, for example research on the returns to birthweight, suggests that the economic cost of this early life inequality is substantial.

Selective serotonin reuptake inhibitor antidepressant use in first trimester pregnancy and risk of specific congenital anomalies: a European register-based study

Evidence of an association between early pregnancy exposure to selective serotonin reuptake inhibitors (SSRI) and congenital heart defects (CHD) has contributed to recommendations to weigh benefits and risks carefully. The objective of this study was to determine the specificity of association between first trimester exposure to SSRIs and specific CHD and other congenital anomalies (CA) associated with SSRI exposure in the literature (signals). A population-based case-malformed control study was conducted in 12 EUROCAT CA registries covering 2.1 million births 1995-2009 including livebirths, fetal deaths from 20 weeks gestation and terminations of pregnancy for fetal anomaly. Babies/fetuses with specific CHD (n = 12,876) and non-CHD signal CA (n = 13,024), were compared with malformed controls whose diagnosed CA have not been associated with SSRI in the literature (n = 17,083). SSRI exposure in first trimester pregnancy was associated with CHD overall (OR adjusted for registry 1.41, 95% CI 1.07-1.86, fluoxetine adjOR 1.43 95% CI 0.85-2.40, paroxetine adjOR 1.53, 95% CI 0.91-2.58) and with severe CHD (adjOR 1.56, 95% CI 1.02-2.39), particularly Tetralogy of Fallot (adjOR 3.16, 95% CI 1.52-6.58) and Ebstein's anomaly (adjOR 8.23, 95% CI 2.92-23.16). Significant associations with SSRI exposure were also found for ano-rectal atresia/stenosis (adjOR 2.46, 95% CI 1.06-5.68), gastroschisis (adjOR 2.42, 95% CI 1.10-5.29), renal dysplasia (adjOR 3.01, 95% CI 1.61-5.61), and clubfoot (adjOR 2.41, 95% CI 1.59-3.65). These data support a teratogenic effect of SSRIs specific to certain anomalies, but cannot exclude confounding by indication or associated factors.

Pratiques parentales coercitives, anxiété et traitement de la peur chez les jeunes en bonne santé: corrélats neuronaux, biologiques, physiologiques et comportementaux

L’adversité tôt dans la vie est associée au développement de symptômes anxieux pouvant perdurer jusqu’à l’âge adulte (Casey et el, 2010, Pine 2003). Des études chez l’adulte suggèrent que ces liens pourraient être associés à des altérations du « circuit de la peur » qui inclut l’amygdale, l’hippocampe antérieur, l’insula et le cortex préfrontal (Marek, 2013, Etkin & Wager, 2007). Ceci a cependant peu été étudié chez les jeunes. L’objectif principal de cette thèse était de définir les corrélats comportementaux, physiologiques, biologiques et neuronaux du traitement de la peur chez les jeunes en bonne santé, en lien ou non avec un historique d’adversité -- sous la forme de pratiques parentales coercitives -- et d’anxiété. D’abord, puisque nous nous intéressions aux pratiques parentales coercitives chroniques, nous avons examiné leur évolution et facteurs de risque, en nous concentrant sur la période de 17 à 72 mois. Un total de 2045 dyades mère-enfant ont été incluses dans une analyse de courbe de croissance latente. Nous avons démontré que la coercition maternelle suit une évolution non linéaire durant cette période et atteint un sommet à 42 mois. Les facteurs de risque relatifs à l’enfant et à la mère, mesurés à 17 mois, permettent de prédire les niveaux de coercition à 42 mois. Finalement, les prédicteurs relatifs à l’enfant et l’efficacité maternelle prédisent l’évolution des pratiques parentales coercitives entre 17 et 72 mois. Ensuite, afin de définir une méthodologie solide pour étudier le traitement de la peur chez des jeunes, nous avons adapté une tâche développée par Lau et ses collaborateurs (2008), employant des visages féminins comme stimuli. Le sexe des participants et des visages employés comme stimuli pouvant potentiellement moduler le traitement de la peur (Kret & de Gelder, 2012; McClure, 2000), nous avons étudié leurs influences respectives sur les réponses électrodermales et subjectives de peur durant le conditionnement et l’extinction de la peur chez 117 jeunes. Nous avons démontré que les stimuli féminins suscitent des réponses davantage comparables entre les garçons et les filles que les stimuli masculins. De plus, nous avons observé un effet du « même sexe », caractérisé par un conditionnement différentiel uniquement face aux stimuli du même sexe que le participant. Finalement, nous avons exploré les différences individuelles et conjointes associées aux différents niveaux de pratiques parentales coercitives et d’anxiété en termes de réponses de peur et d’activité cérébrale, durant le conditionnement et l’extinction de la peur chez 84 jeunes. Nous avons démontré que la coercition est spécifiquement associée au fonctionnement du lobe temporal médian et aux interactions entre l’amygdale et l’insula, durant le conditionnement. Durant l’extinction, les niveaux d’anxiété étaient associés à des différences spécifiques d’activation du gyrus cingulaire antérieur (GCA) dorsal. Enfin, les pratiques parentales coercitives et l’anxiété interagissent et viennent moduler la connectivité fonctionnelle amygdale - GCA rostral, l’activation d’une sous-région du GCA dorsal et les réponses subjectives de peur. Ces résultats ajoutent une pièce au casse-tête des neurosciences développementales et fournissent des pistes intéressantes pour le développement d’interventions futures.

Effects of ocean acidification on embryo development: Does encapsulation matter?

As the concentration of CO2 in surface seawaters increases (ocean acidification, or OA) the saturation of calcium carbonate decreases, preventing marine organisms from creating shells and other calcified structures. These effects of elevated CO2 on calcification have been previously shown in free-spawning larvae, but are not as well-studied in larvae that spend their early life stages in encapsulation. The focus of our study was to determine what effects CO2 would have on a diversity of encapsulated embryos, and whether different types of encapsulating structures provided different levels of protection against OA. We found only a moderate larval response to low (600 ppm), medium (1050 ppm), and high (1500 ppm) CO2 concentrations across all species taken as a whole, but did observe that several species/ populations exhibited a decline in shell length with no corresponding decline in inorganic content. This suggests that while calcification was not significantly decreased by our OA conditions, perhaps the morphology of certain shells changed, becoming wider and shorter. Our hatch times, which increased with elevated CO2, confirmed that increased CO2 placed embryos under stress during development.

Genetic effect of domestication selective pressures on Pacific oyster at larval stage

Among bivalve species, the Pacific oyster, Crassostrea gigas, is the most economically important bivalve production over the world. Today, C. gigas is subject to an important production effort that leads to an intensive artificial selection. Larval stage is relatively unknown, specifically in a domestication context. Genetic consequence of artificial selection is still at a preliminary study. We aimed to tackle the consequence of inconscient domestication on the variance reproductive success focusing on larval stage, keystone of the life cycle. We studied two kinds of specific selective processes that common hatchery rearing practices exert : the effect of discarding the smallest larvae on genetic diversity and the artificial environment rearing effect via the temperature providing a contrast resembling wild versus hatchery conditions (20 and 26°C). In order to monitor the effect of the selection of fast growing larvae by sieving, growth variability and genetic diversity in a larval population descended from a factorial breeding was studied. We used a mixed-family approach to reduce potentially confounding environmental biais. The retrospective assignment of individuals to family groups has been performed using a three microsatellite markers set. Two different rearing were carried out in parallel. For three (replicates) 50-l tanks, the smallest larvae were progressively discarded by selective sieving, whereas for the three others no selective sieving was performed. The intensity of selective sieving was adjusted so as to discard 50% of the larvae over the whole rearing period in a progressive manner. As soon as the larvae reached the pediveliger stage, ready to settle larvae were sampled for genetic analysis. Regarding the artificial environment rearing effect via the temperature, we used a similar mixed-family approach. The progeny from a factorial breeding design was divided as follows: three (replicates) 50-l tanks were dedicaced to a rearing at 26°C versus 20°C for three others 50-l tanks. The whole size variability was preserved for this experiment. Individual growth measurements for larvae genetically identified have been performed at days 22 and 30 after fertilization for both conditions. In a same way, we collected individual measurements for genotyped juvenile oysters (80 days after fertilization). At a phenotypic scale, relative survival and settlement success for larvae with sieving were higher. Sieving appears as a time-saving process associated with a better relative survival ratio. But in the same time, our results confirm that a significant genetic variability exist for early developmental traits in the Pacific oyster. This is congruent with the results already obtained that investigated genetic variability and genetic correlations in early life-history traits of Crassostrea gigas. Discarding around 50% of the smallest larvae can lead to significant selection at the larval stage.

Interview with Charles W. Peck

Interview in five sessions, October-November 2003, with Charles W. Peck, professor of physics (now emeritus) in the Division of Physics, Mathematics, and Astronomy. He recalls his early life in South Texas and his interest in radio; first year of college at Texas Arts & Industries; three more years at New Mexico College of Agriculture & Mechanical Arts. Recalls graduate studies at Caltech with Murray Gell-Mann, H. P. Robertson, Robert Walker, Richard A. Dean, W. R. Smythe. Works on increasing intensity and stability of the Caltech synchrotron, with Walker, Matt Sands, and Alvin Tollestrup; 1964 thesis on K-lambda photoproduction. Joins the faculty as an assistant professor in 1965. Discusses his various teaching assignments, including an embarrassing moment when Richard Feynman attended one of his freshman physics lectures. Discusses his research at the Stanford Linear Accelerator Center and Lawrence Radiation Laboratory’s Bevatron. Collaboration with UC Berkeley and SLAC on “crystal ball” detector for SLAC’s SPEAR storage ring. Taking the crystal ball to DESY, in Hamburg. Works with Barry Barish at Gran Sasso laboratory in Italy, on MACRO; search for magnetic monopoles. He also discusses his administration work at Caltech, as executive officer for physics (1983-1986) and as PMA division chair from 1993 to 1998, when he immediately had to deal with the troubles plaguing LIGO [Laser Interferometer Gravitational-wave Observatory]. Detailed discussion of the LIGO contretemps and how it was settled, and of turning Big Bear Solar Observatory over to the New Jersey Institute of Technology. Advent of David Baltimore as Caltech president; attempt to recruit Ed Witten.

Spatial and Temporal Dynamics of Larval Atlantic Menhaden on the East Coast of the United States

Atlantic Menhaden Brevoortia tyrannus is a commercially and ecologically important forage fish abundant on the Atlantic Coast of the United States. We conducted spatial and temporal analyses of larval Atlantic Menhaden using data collected from two large-scale ichthyoplankton programs during 1977-1987 and 1999-2013 to construct indices of larval abundance and survival over time, evaluate how environmental factors affect early life survival, and examine how larvae are distributed in space to gain knowledge on spawning and larval dispersal. Over time, we found larval abundance to increase, while early life survival declined. Coastal temperature, wind speed, and Atlantic Multidecadal Oscillation were found to potentially explain some of this decline in survival. Over both periods, we found evidence spawning predominantly occurs near shore, from New York to North Carolina, increasing in intensity southwards. While the general spatial patterns were consistent, we observed some localized variation and overall expansion of occupied area by larvae.

Aspects of migration, size structure and mortality of juvenile Nile perch in the Mwanza Gulf of Lake Victoria

A detailed study of the early life of fishes forms one of the very important aspects with respect to recruitment mechanism and proper uneterstanding of the dynamics leading to sustainance of fish populations. It should be the central theme of the fisheries biologist and managers to extract the bilogical information relevant to the proper understanding of this part of the population. A number of studies in the Mwanza gulf and Lake Victoria have emphasized the need to monitor the fishery by conducting observations of stock size, migration, catch effort data and growth of big specimen (Acere 1981, Goudsward et al 1984, Asila. Ogari 1988 and Okemwa 1984). The present paper discusses the preliminary information on the size structure, mortality and migration of juvenile Nile perch. The long term objectives of the programme is aimed at describing the size structure, growth, mortality, recruitment pattern and population dynamics of the Nile perch up to 30 cm total length in the, Mwanza Gulf.