Reef Coral Reproduction in the Eastern Pacific: Costa Rica, Panamá, and the Galápagos Islands (Ecuador). VI. Agariciidae, Pavona clavus

The reproductive ecology of the zooxanthellate reef coral Pavona clavus was investigated at several sites in Costa Rica, Panama, and the Galapagos Islands (Ecuador) over the period 1985–2009. Pavona clavus displayed stable gonochorism as only five hermaphrodites were found in 590 samples. At four of five locations, sex ratios were skewed toward female dominance; however, at Saboga Island (Panama) male colonies predominated. In Panama, sexual maturity was observed in an estimated eight year old female colony, and several colonies of 10–20 years of age demonstrated gametogenesis. Sexual activity was observed at all study sites, but gamete development occurred in only 14–31% of colonies sampled sporadically. Seasonality of gametogenic activity occurred predominantly during the warm/wet season, June to August, at mainland sites (Cano Island, Costa Rica, and Gulfs of Chiriqui and Panama, Panama). This pattern was repeated in the Galapagos Islands, but mainly from March to May when seasonally high sea temperatures and rainfall prevailed there. Histological sampling and field observations indicated that spawning was centered around the full moon, most frequently on lunar day 17, and near sunset (1,800 h). Mean fecundity (mature ova cm-2 live tissue) estimates were significantly different for two sites and ranged from ~1,780 (Saboga Island, Gulf of Panama, seasonally upwelling) to ~4,280 (Uva Is, Gulf of Chiriqui, nonupwelling). Assuming three annual spawning events colony-1 (August, September, October), extrapolation of minimum and maximum fecundities yield 5,340 and 12,840 ova cm-2 year-1. Seasonal, lunar, and diel spawning patterns in nine zooxanthellate species at Uva Island indicate asynchronous coral community spawning

Reproductive Ecology of the Azooxanthellate Coral Tubastraea coccinea in the Equatorial Eastern Pacific: Part V. Dendrophylliidae

The reproductive ecology of Tubastraea coccinea Lesson, an azooxanthellate tropical scleractinian coral, was studied over various periods from 1985 to 2006 at four principal eastern Pacific locations in Costa Rica, Panamá, and the Galápagos Islands (Ecuador). This small (polyp diameter 0.8–1.0 cm), relatively cryptic species produced ova and planulae year round, including colonies with as few as 2–10 polyps. Of 424 colonies examined histologically, 13.7% contained both ova and sperm. Mature ova varied in diameter from ~300 to 800 µm and the time from spawning and fertilization of oocytes to release of brooded planulae was about 6 weeks. Planulae were 0.5–1.5 mm long and they settled and metamorphosed on a variety of substrates after 1–3 days. Spermaries, though more difficult to distinguish in histological sections, were present throughout the year. Spent spermaries were never observed in sections, but several colonies in Panamá and the Galápagos Islands released sperm from night one to night five after full moon, indicating the potential for cross-fertilization among colonies. Planula release was observed at Uva Island (Panamá) in March, May, June, and July, and in general planula presence was higher at warm ocean temperatures at all sites, whether or not the sites were inXuenced by seasonal upwelling. Annual fecundity estimates for T. coccinea are comparable with other high fecundity brooding species, including the zooxanthellate Porites panamensis, with which it co-occurs in Panamá. Tubastraea coccinea is widely distributed in the tropical Indo-Pacific and has colonized substrates in the western Atlantic. In addition to the reproductive characteristics described in the present study, other features of the biology of T. coccinea, such as an ability to withstand conditions that produce bleaching and mortality in zooxanthellate species, may account for its widespread, low-latitude distribution in multiple oceans

Characterisation of tumour vasculature in mouse brain by USPIO contrast-enhanced MRI

To enhance the success rate of antiangiogenic therapies in the clinic, it is crucial to identify parameters for tumour angiogenesis that can predict response to these therapies. In brain tumours, one such parameter is vascular leakage, which is a response to tumour-derived vascular endothelial growth factor-A and can be measured by Gadolinium-DTPA (Gd-DTPA)-enhanced magnetic resonance imaging (MRI). However, as vascular permeability and angiogenesis are not strictly coupled, tumour blood volume may be another potentially important parameter. In this study, contrast-enhanced MR imaging was performed in three orthotopic mouse models for human brain tumours (angiogenic melanoma metastases and E34 and U87 human glioma xenografts) using both Gd-DTPA to detect vascular leakage and ultrasmall iron oxide particles (USPIO) to measure blood volume. Pixel-by-pixel maps of the enhancement in the transverse relaxation rates (ΔR2 and ΔR2*) after injection of USPIO provided an index proportional to the blood volume of the microvasculature and macrovasculature, respectively, for each tumour. The melanoma metastases were characterised by a blood volume and vessel leakage higher than both glioma xenografts. The U87 glioblastoma xenografts displayed higher permeability and blood volume in the rim than in the core. The E34 glioma xenografts were characterised by a relatively high blood volume, accompanied by only a moderate blood–brain barrier disruption. Delineation of the tumour was best assessed on post-USPIO gradient-echo images. These findings suggest that contrast-enhanced MR imaging using USPIOs and, in particular, ΔR2 and ΔR2* quantitation, provides important additional information about tumour vasculature

Physico-Chemical Evaluation of Rationally Designed Melanins as Novel Nature-Inspired Radioprotectors

Melanin, a high-molecular weight pigment that is ubiquitous in nature, protects melanized microorganisms against high doses of ionizing radiation. However, the physics of melanin interaction with ionizing radiation is unknown.We rationally designed melanins from either 5-S-cysteinyl-DOPA, L-cysteine/L-DOPA, or L-DOPA with diverse structures as shown by elemental analysis and HPLC. Sulfur-containing melanins had higher predicted attenuation coefficients than non-sulfur-containing melanins. All synthetic melanins displayed strong electron paramagnetic resonance (2.14.10(18), 7.09.10(18), and 9.05.10(17) spins/g, respectively), with sulfur-containing melanins demonstrating more complex spectra and higher numbers of stable free radicals. There was no change in the quality or quantity of the stable free radicals after high-dose (30,000 cGy), high-energy ((137)Cs, 661.6 keV) irradiation, indicating a high degree of radical stability as well as a robust resistance to the ionizing effects of gamma irradiation. The rationally designed melanins protected mammalian cells against ionizing radiation of different energies.We propose that due to melanin's numerous aromatic oligomers containing multiple pi-electron system, a generated Compton recoil electron gradually loses energy while passing through the pigment, until its energy is sufficiently low that it can be trapped by stable free radicals present in the pigment. Controlled dissipation of high-energy recoil electrons by melanin prevents secondary ionizations and the generation of damaging free radical species

Magnetic resonance imaging of brain angiogenesis after stroke

Stroke is a major cause of mortality and long-term disability worldwide. The initial changes in local perfusion and tissue status underlying loss of brain function are increasingly investigated with noninvasive imaging methods. In addition, there is a growing interest in imaging of processes that contribute to post-stroke recovery. In this review, we discuss the application of magnetic resonance imaging (MRI) to assess the formation of new vessels by angiogenesis, which is hypothesized to participate in brain plasticity and functional recovery after stroke. The excellent soft tissue contrast, high spatial and temporal resolution, and versatility render MRI particularly suitable to monitor the dynamic processes involved in vascular remodeling after stroke. Here we review recent advances in the field of MR imaging that are aimed at assessment of tissue perfusion and microvascular characteristics, including cerebral blood flow and volume, vascular density, size and integrity. The potential of MRI to noninvasively monitor the evolution of post-ischemic angiogenic processes is demonstrated from a variety of in vivo studies in experimental stroke models. Finally, we discuss some pitfalls and limitations that may critically affect the accuracy and interpretation of MRI-based measures of (neo)vascularization after stroke

Ocean acidification can mediate biodiversity shifts by changing biogenic habitat

The effects of ocean acidification (OA) on the structure and complexity of coastal marine biogenic habitat have been broadly overlooked. Here we explore how declining pH and carbonate saturation may affect the structural complexity of four major biogenic habitats. Our analyses predict that indirect effects driven by OA on habitat-forming organisms could lead to lower species diversity in coral reefs, mussel beds and some macroalgal habitats, but increases in seagrass and other macroalgal habitats. Available in situ data support the prediction of decreased biodiversity in coral reefs, but not the prediction of seagrass bed gains. Thus, OA-driven habitat loss may exacerbate the direct negative effects of OA on coastal biodiversity; however, we lack evidence of the predicted biodiversity increase in systems where habitat-forming species could benefit from acidification. Overall, a combination of direct effects and community-mediated indirect effects will drive changes in the extent and structural complexity of biogenic habitat, which will have important ecosystem effects

Rapid bioerosion in a tropical upwelling coral reef

Coral reefs persist in an accretion-erosion balance, which is critical for understanding the natural variability of sediment production, reef accretion, and their effects on the carbonate budget. Bioerosion (i.e. biodegradation of substrate) and encrustation (i.e. calcified overgrowth on substrate) influence the carbonate budget and the ecological functions of coral reefs, by substrate formation/consolidation/erosion, food availability and nutrient cycling. This study investigates settlement succession and carbonate budget change by bioeroding and encrusting calcifying organisms on experimentally deployed coral substrates (skeletal fragments of Stylophora pistillata branches). The substrates were deployed in a marginal coral reef located in the Gulf of Papagayo (Costa Rica, Eastern Tropical Pacific) for four months during the northern winter upwelling period (December 2013 to March 2014), and consecutively sampled after each month. Due to the upwelling environmental conditions within the Eastern Tropical Pacific, this region serves as a natural laboratory to study ecological processes such as bioerosion, which may reflect climate change scenarios. Time-series analyses showed a rapid settlement of bioeroders, particularly of lithophagine bivalves of the genus Lithophaga/ Leiosolenus (Dillwyn, 1817), within the first two months of exposure. The observed enhanced calcium carbonate loss of coral substrate (>30%) may influence seawater carbon chemistry. This is evident by measurements of an elevated seawater pH (>8.2) and aragonite saturation state (Ωarag >3) at Matapalo Reef during the upwelling period, when compared to a previous upwelling event observed at a nearby site in distance to a coral reef (Marina Papagayo). Due to the resulting local carbonate buffer effect of the seawater, an influx of atmospheric CO2 into reef waters was observed. Substrates showed no secondary cements in thin-section analyses, despite constant seawater carbonate oversaturation (Ωarag >2.8) during the field experiment. Micro Computerized Tomography (μCT) scans and microcast-embeddings of the substrates revealed that the carbonate loss was primarily due to internal macrobioerosion and an increase in microbioerosion. This study emphasizes the interconnected effects of upwelling and carbonate bioerosion on the reef carbonate budget and the ecological turnovers of carbonate producers in tropical coral reefs under environmental change.Sistema Nacional de Áreas de Conservación/[028-2013-SINAC]/SINAC/Costa RicaSistema Nacional de Áreas de Conservación/[72-2013-SINAC]/SINAC/Costa RicaUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Ciencias del Mar y Limnología (CIMAR

Species richness of motile cryptofauna across a gradient of reef framework erosion

Coral reef ecosystems contain exceptionally high concentrations of marine biodiversity, potentially encompassing millions of species. Similar to tropical rainforests and their insects, the majority of reef animal species are small and cryptic, living in the cracks and crevices of structural taxa (trees and corals). Although the cryptofauna make up the majority of a reef's metazoan biodiversity, we know little about their basic ecology. We sampled motile cryptofaunal communities from both live corals and dead carbonate reef framework across a gradient of increasing erosion on a reef in Pacific Panama. A total of 289 Operational Taxonomic Units (OTUs) from six phyla were identified. We used species-accumulation models fitted to individual- and sample-based rarefaction curves, as well as seven nonparametric richness estimators to estimate species richness among the different framework types. All procedures predicted the same trends in species richness across the differing framework types. Estimated species richness was higher in dead framework (261-370 OTUs) than in live coral substrates (112-219 OTUs). Surprisingly, richness increased as framework structure was eroded: coral rubble contained the greatest number of species (227-320 OTUs) and the lowest estimated richness of 47-115 OTUs was found in the zone where the reef framework had the greatest vertical relief. This contradicts the paradigm that abundant live coral indicates the apex of reef diversity

Seawater carbonate chemistry and benthic community composition at reefs of Bolinao, Philippines

Coral reefs are vulnerable to global ocean acidification (OA) and local human activities will continue to exacerbate coastal OA. In Bolinao, Philippines, intense unregulated fish mariculture has resulted in regional eutrophication. In order to examine the coastal acidification associated with this activity and the impact on nearby coral reefs, water quality and carbonate chemistry parameters were measured at three reef sites, a mariculture site and an offshore, minimally impacted control site during both the wet and dry season. Additionally, benthic community composition was characterized at reef sites, and both autonomous carbonate chemistry sampling and high-frequency pH measurements were used to characterize fine-scale (diel) temporal variability. Water quality was found to be poorer at all reefs during the wet season, when there was stronger outflow of waters from the mariculture area. Carbonate chemistry parameters differed significantly across the reef flat and between seasons, with more acidic conditions occurring during the dry season and increased primary production suppressing further acidification during the wet season. Significant relationships of both total alkalinity (TA) and dissolved inorganic carbon (DIC) with salinity across all stations may imply outflow of acidified water originating from the mariculture area where pH values as low as 7.78 were measured. This apparent mariculture-induced coastal acidification was likely due to organic matter respiration as sustained mariculture will continue to deliver organic matter. While TA-DIC vector diagrams indicate greater contribution of net primary production, net calcification potential in the nearest reef to mariculture area may already be diminished. The two farther reefs, characterized by higher coral cover, indicates healthier ecosystem functioning. Here we show that unregulated fish mariculture activities can lead to localized acidification and impact reef health. As these conditions at times approximate those projected to occur globally due to OA, our results may provide insight into reef persistence potential worldwide. These results also underscore the importance of coastal acidification and indicate that actions taken to mitigate OA on coral reefs should address not only global CO2 emissions but also local perturbations, in this case fish mariculture-induced eutrophication

Seawater carbonate chemistry and vertical movement of stone crab larvae

Anthropogenic activities are increasing ocean temperature and decreasing ocean pH. Some coastal habitats are experiencing increases in organic runoff, which when coupled with a loss of vegetated coastline can accelerate reductions in seawater pH. Marine larvae that hatch in coastal habitats may not have the ability to respond to elevated temperature and changes in seawater pH. This study examined the response of Florida stone crab (Menippe mercenaria) larvae to elevated temperature (30°C control and 32°C treatment) and CO2-induced reductions in pH (8.05 pH control and 7.80 pH treatment). We determined whether those singular and simultaneous stressors affect larval vertical movement at two developmental stages. Geotactic responses varied between larval stages. The direction and rate of the vertical displacement of larvae were dependent on pH rather than temperature. Stage III larvae swam upwards under ambient pH conditions, but swam downwards at a faster rate under reduced pH. There was no observable change in the directional movement of Stage V larvae. The reversal in orientation by Stage III larvae may limit larval transport in habitats that experience reduced pH and could pose challenges for the northward dispersal of stone crabs as coastal temperatures warm