Successful external fertilization in turbulent environments.

Mathematical and experimental simulations predict that external fertilization is unsuccessful in habitats characterized by high water motion. A key assumption of such predictions is that gametes are released in hydrodynamic regimes that quickly dilute gametes. We used fucoid seaweeds to examine whether marine organisms in intertidal and subtidal habitats might achieve high levels of fertilization by restricting their release of gametes to calm intervals. Fucus vesiculosus L. (Baltic Sea) released high numbers of gametes only when maximal water velocities were below ca. 0.2 m/s immediately prior to natural periods of release, which occur in early evening in association with lunar cues. Natural fertilization success measured at two sites was always close to 100%. Laboratory experiments confirmed that (i) high water motion inhibits gamete release by F. vesiculosus and by the intertidal fucoids Fucus distichus L. (Maine) and Pelvetia fastigiata (J. Ag.) DeToni (California), and (ii) showed that photosynthesis is required for high gamete release. These data suggest that chemical changes in the boundary layer surrounding adults during photosynthesis and/or mechanosensitive channels may modulate gamete release in response to changing hydrodynamic conditions. Therefore, sensitivity to environmental factors can lead to successful external fertilization, even for species living in turbulent habitats.

Molecular cloning of a protein kinase whose phosphorylation is regulated by genetic adhesion during Chlamydomonas fertilization.

Fertilization in Chlamydomonas is initiated by adhesive interactions between gametes of opposite mating types through flagellar glycoproteins called agglutinins. Interactions between these cell adhesion molecules signal for the activation of adenylyl cyclase through an interplay of protein kinases and ultimately result in formation of a diploid zygote. One of the early events during adhesion-induced signal transduction is the rapid inactivation of a flagellar protein kinase that phosphorylates a 48-kDa protein in the flagella. We report the biochemical and molecular characterization of the 48-kDa protein. Experiments using a bacterially expressed fusion protein show that the 48-kDa protein is capable of autophosphorylation on serine and tyrosine and phosphorylation of bovine beta-casein on serine, confirming that the 48-kDa protein itself has protein kinase activity. This protein kinase exhibits limited homology to members of the eukaryotic protein kinase superfamily and may be an important element in a signaling pathway in fertilization.

Effects of the herbicide diuron on the early life history stages of coral

The effects of the herbicide diuron on the early life history stages of broadcast spawning and brooding corals were examined in laboratory experiments. Fertilisation of Acropora millepora and Montipora aequituberculata oocytes were not inhibited at diuron concentrations of up to 1000 mu gl(-1). Metamorphosis of symbiont-free A. millepora larvae was only significantly inhibited at 300 mu gl(-1) diuron. Pocillopora damicornis larvae, which contain symbiotic dinoflagellates, were able to undergo metamorphosis after 24h exposure to diuron at 1000 mu gl(-1). Two-week old P. damicornis recruits on the other hand were as susceptible to diuron as adult colonies, with expulsion of symbiotic dinoflagellates (bleaching) evident at 10 mu gl(-1) diuron after 96 h exposure. Reversible metamorphosis was observed at high diuron concentrations, with fully bleached polyps escaping from their skeletons. Pulse amplitude modulation (PAM) chlorophyll fluorescence techniques demonstrated a reduction in photosynthetic efficiency (Delta F/F'(m)) in illuminated P. dami- cornis recruits after a 2h exposure to 1 mu gl(-1) diuron. The dark-adapted quantum yields (F-v/F-m also declined, indicating chronic photoinhibition and damage to photosystem H. Crown Copyright (c) 2004 Published by Elsevier Ltd. All rights reserved.

Seawater carbonate chemistry and biological processes during experiments with early life stages of the blue mussel Mytilus edulis, 2010

Several experiments have shown a decrease of growth and calcification of organisms at decreased pH levels. There is a growing interest to focus on early life stages that are believed to be more sensitive to environmental disturbances such as hypercapnia. Here, we present experimental data, acquired in a commercial hatchery, demonstrating that the growth of planktonic mussel (Mytilus edulis) larvae is significantly affected by a decrease of pH to a level expected for the end of the century. Even though there was no significant effect of a 0.25-0.34 pH unit decrease on hatching and mortality rates during the first 2 days of development nor during the following 13-day period prior to settlement, final shells were respectively 4.5±1.3 and 6.0±2.3% smaller at pHNBS~7.8 (pCO2~1100-1200 µatm) than at a control pHNBS of ~8.1 (pCO2~460-640 µatm). Moreover, a decrease of 12.0±5.4% of shell thickness was observed after 15d of development. More severe impacts were found with a decrease of ~0.5 pHNBS unit during the first 2 days of development which could be attributed to a decrease of calcification due to a slight undersaturation of seawater with respect to aragonite. Indeed, important effects on both hatching and D-veliger shell growth were found. Hatching rates were 24±4% lower while D-veliger shells were 12.7±0.9% smaller at pHNBS~7.6 (pCO2~1900 µatm) than at a control pHNBS of ~8.1 (pCO2~540 µatm). Although these results show that blue mussel larvae are still able to develop a shell in seawater undersaturated with respect to aragonite, the observed decreases of hatching rates and shell growth could lead to a significant decrease of the settlement success. As the environmental conditions considered in this study do not necessarily reflect the natural conditions experienced by this species at the time of spawning, future studies will need to consider the whole larval cycle (from fertilization to settlement) under environmentally relevant conditions in order to investigate the potential ecological and economical losses of a decrease of this species fitness in the field.

Seawater carbonate chemistry and sperm swimming speed, fertilization success of the Australasian sea urchin Heliocidaris erythrogramma in lab experiment

Background: Climate change will lead to intense selection on many organisms, particularly during susceptible early life stages. To date, most studies on the likely biotic effects of climate change have focused on the mean responses of pooled groups of animals. Consequently, the extent to which inter-individual variation mediates different selection responses has not been tested. Investigating this variation is important, since some individuals may be preadapted to future climate scenarios. Methodology/Principal Findings: We examined the effect of CO2-induced pH changes ("ocean acidification") in sperm swimming behaviour on the fertilization success of the Australasian sea urchin Heliocidaris erythrogramma, focusing on the responses of separate individuals and pairs. Acidification significantly decreased the proportion of motile sperm but had no effect on sperm swimming speed. Subsequent fertilization experiments showed strong inter-individual variation in responses to ocean acidification, ranging from a 44% decrease to a 14% increase in fertilization success. This was partly explained by the significant relationship between decreases in percent sperm motility and fertilization success at delta pH = 0.3, but not at delta pH = 0.5. Conclusions and Significance: The effects of ocean acidification on reproductive success varied markedly between individuals. Our results suggest that some individuals will exhibit enhanced fertilization success in acidified oceans, supporting the concept of 'winners' and 'losers' of climate change at an individual level. If these differences are heritable it is likely that ocean acidification will lead to selection against susceptible phenotypes as well as to rapid fixation of alleles that allow reproduction under more acidic conditions. This selection may ameliorate the biotic effects of climate change if taxa have sufficient extant genetic variation upon which selection can act.

Ocean acidification and its potential effects on the early life-history of non-calcifying and calcifying echinoderm (Odontaster validus, Patiriella regularis and Arachnoides placenta) larvae, 2011

Ocean acidification, as a result of increased atmospheric CO2, has the potential to adversely affect the larval stages of many marine organisms and hence have profound effects on marine ecosystems. This is the first study of its kind to investigate the effects of ocean acidification on the early life-history stages of three echinoderms species, two asteroids and one irregular echinoid. Potential latitudinal variations on the effects of ocean acidification were also investigated by selecting a polar species (Odontaster validus), a temperate species (Patiriella regularis), and a tropical species (Arachnoides placenta). The effects of reduced seawater pH levels on the fertilization of gametes, larval survival and morphometrics on the aforementioned species were evaluated under experimental conditions. The pH levels considered for this research include ambient seawater (pH 8.1 or pH 8.2), levels predicted for 2100 (pH 7.7 and pH 7.6) and the extreme pH of 7.0, adjusted by bubbling CO2 gas into filtered seawater. Fertilization for Odontaster validus and Patiriella regularis for the predicted scenarios for 2100 was robust, whereas fertilization was significantly reduced in Arachnoides placenta. Larval survival was robust for the three species at pH 7.8, but numbers declined when pH dropped below 7.6. Normal A. placenta larvae developed in pH 7.8, whereas smaller larvae were observed for O. validus and P. regularis under the same pH treatment. Seawater pH levels below 7.6 resulted in smaller and underdeveloped larvae for all three species. The greatest effects were expected for the Antarctic asteroid O. validus but overall the tropical sand dollar A. placenta was the most affected by the reduction in seawater pH. The effects of ocean acidification on the asteroids O. validus and P. regulars, and the sand dollar A. placenta are species-specific. Several parameters, such as taxonomic differences, physiology, genetic makeup and the population's evolutionary history may have contributed to this variability. This study highlights the vulnerability of the early developmental stages and the complexity of ocean acidification. However, future research is needed to understand the effects at individual, community and ecosystem levels.

Impacts of Deepwater Horizon oil and associated dispersant on early development of the Eastern oyster Crassostrea virginica

The explosion of the Deepwater Horizon (DWH) oil platform resulted in large amounts of crude oil and dispersant Corexit 9500A® released into the Gulf of Mexico and coincided with the spawning season of the oyster, Crassostrea virginica. The effects of exposing gametes and embryos of C. virginica to dispersant alone (Corexit), mechanically (HEWAF) and chemically dispersed (CEWAF) DWH oil were evaluated. Fertilization success and the morphological development, growth, and survival of larvae were assessed. Gamete exposure reduced fertilization (HEWAF: EC201 h = 1650 μg tPAH50 L− 1; CEWAF: EC201 h = 19.4 μg tPAH50 L− 1; Corexit: EC201 h = 6.9 mg L− 1). CEWAF and Corexit showed a similar toxicity on early life stages at equivalent nominal concentrations. Oysters exposed from gametes to CEWAF and Corexit experienced more deleterious effects than oysters exposed from embryos. Results suggest the presence of oil and dispersant during oyster spawning season may interfere with larval development and subsequent recruitment.

Development of super early genotypes for the dry bean (Phaseolus vulgaris) as affected by nitrogen management.

The super early genotypes (SEG) of dry bean (Phaseolus vulgaris L.) have a shorter life cycle (65-75 days) when compared with the season length of traditional cultivars (90-100 days). Timing of nitrogen top-dressing fertilization could be different because of this reduction in length of the SEG life cycle. This study aimed at characterizing, by using growth analysis and vegetation index, super early genotypes of dry bean development as affected by timing of nitrogen application. Field experiments were conducted in the 2014 and 2015 growing seasons in central Brazil with a randomized block experimental design with split plots scheme and four replicates. The plots comprised the dry bean genotypes (Colibri ? check cultivar, CNFC 15873, CNFC 15874, and CNFC 15875), and subplots comprised applications of N at different timings: 90 kg of N at sowing, 90 kg N at top-dressing; 45 kg of N at sowing plus 45 kg at top-dressing, with urea as the source of N. We also used a control treatment without N application. The CNFC 15874 super early genotype of dry bean had the higher grain yield (2776 kg ha-1) and differed from the CNFC 15873 genotype (2492 kg ha-1). Nitrogen fertilization allowed higher grain yield (2619 kg ha-1, when applied N at sowing, 2605 kg ha-1, when applied N at sowing and at top-dressing, and 2680 kg ha-1, when applied N at top-dressing) than the control, 2360 kg ha-1 (no N fertilization). The time of N fertilization in super early genotype of dry bean did not affect grain yield.

Growth, nutrient accumulation in leaves and grain yield of super early genotypes of common bean.

There is a lack of researches that evaluate the development and nutrient accumulation in super early genotypes of common bean for the elaboration of fertilization programs. This study aimed at characterizing the development; N, P, K, Ca and Mg accumulation by leaves; grain yield; and yield components of super early genotypes of common bean. Field experiments were conducted in a randomized blocks design, with four replications. The treatments consisted of the IPR Colibri (control), CNFC 15873, CNFC 15874 and CNFC 15875 genotypes. Plants were sampled throughout the common bean development, being divided into leaves, stems and pods. After determining the dry matter, the contents of N, P, K, Ca and Mg accumulated in leaves were estimated. At harvesting, the grain yield and yield components were evaluated. The biomass accumulation in stems and leaves occurred until the flowering stage, and then it started in the pods until harvesting. The genotypes that absorbed more nitrogen and phosphorus had a higher grain yield. The average growing season of super early genotypes was 70 days (winter) and 63 days (summer). CNFC 15874 was the most productive genotype in the winter, with grain yield similar to the IPR Colibri cultivar (control). In the summer, CNFC 15873 and CNFC 15875 achieved grain yield similar to the IPR Colibri cultivar.

Lady Nugent and Tom Cringle on the veranda : early nineteenth century observations on a Caribbean architectural feature

This study of the veranda as seen through the eyes of Lady Maria Nugent and Michael Scott, alias Tom Cringle, clearly demonstrates the important role that the piazza, as it was then more commonly known, played in the life of early nineteenth century Caribbean colonial society. The popularity of the veranda throughout the region, in places influenced by different European as well as African cultures, and among all classes of people, suggests that the appeal of this typical feature was based on something more than architectural fashion. A place of relative comfort in hot weather, the veranda is also a space at the interface of indoors and outdoors which allows for a wide variety of uses, for solitary or small or large group activities, many of which were noted by Nugent and Scott. Quintessentially, the veranda is a place in which to relax and take pleasure, not least of which is the enjoyment of the prospect, be it a panoramic view, a peaceful garden or a lively street scene. Despite the great changes in the nature of society, in the Caribbean and in many other parts of the world, the veranda and related structures such as the balcony continue to play at least as important a role in daily life as they did two centuries ago. The veranda of today’s Californian or Australian bungalow, and the balcony of the apartment block in the residential area of the modern city are among the contemporary equivalents of the lower and upper piazzas of Lady Nugent’s and Tom Cringle’s day.