Ostreopsis cf. ovata (Dinophyta) bloom in an equatorial island of the Atlantic Ocean

The epi-benthic dinoflagellate Ostreopsis cf. ovata Fukuyo has an increasingly global distribution. In Brazil there are reports of O. cf. ovata along the coast from 8°S to 27°S latitude and blooms have been registered on the Rio de Janeiro coastline. In the current study, an O. cf. ovata bloom is reported at Saint Paul's Rocks (0°55'10″N; 29°20'33″W), between the southern and northern hemispheres. The Archipelago is not inhabited and not subjected to eutrophication, due to isolation, and sustains a number of endemic species. Therefore, blooms of O. cf. ovata may potentially cause demise to trophic chains by affecting marine invertebrates and vertebrates.     

Mapping seascapes of international environmental arrangements in the Coral Triangle

The Coral Triangle Initiative on Coral Reefs, Fisheries and Food Security (CTI), adopted recently in response to the degradation of coastal and marine environments in the Southeast Asia-Pacific’s Coral Triangle, emphasises the need for using existing international and regional fora to promote implementation. Large-scale marine initiatives, including the CTI, very often must contend with a remarkably complex institutional system. This raises the question of whether and how such complexity can be conducive to marine resources management. To answer this question, this paper aims to better understand the governance context in which the CTI was established (i.e., map governance fragmentation/complexity), and explore how such a context may support the implementation of the CTI goals (i.e., examine normative interplay). To conduct this examination, it uses an objective method that allows users to view and explore institutional arrangements through a network approach. By documenting the system of existing institutions in the Coral Triangle, the study shows that the Coral Triangle governance system is illustrative of those of international environmental governance. It involves multiple policy domains, and features different institutional arrangements and variability in terms of geographical scope and main subject matter. Such a system is complex and fragmented, marked by jurisdiction and functional overlaps. The paper suggests interplay management, such as inter-institutional learning and enhancing institutional synergy, as a promising process to promote inter-institutional coordination.     

Metamorphism and exhumation of basement gneiss domes in the Quadrilátero Ferrífero:Two stage dome-and-keel evolution?

The presence of dome-and-keel provinces in Archean cratons has been connected with the initiation of plate tectonics on Earth as these features are most commonly observed in Archean rocks.The Quadrilátero Ferrífero in Brazil has been identified as a Paleoproterozoic dome-and-keel province for more than three decades.The prevailing model suggests that it formed during the Rhyacian Transamazonian orogeny,making it unique among dome-and-keel provinces.However,a lack of appropriate lithologies,datable minerals and the metamorphic overprint of later orogenesis has resulted in a cryptic metamorphic record for the formation of this dome-and-keel province.A clinopyroxene-bearing migmatite from the core of the Ba??o dome has peak P-T conditions of 5-7 kbar and 700-750 ℃ and a published age of ca.2730 Ma based on U-Pb ages of zircon from leucosomes,suggesting that this age represents the migmatisation event.A fine-grained epidote-albite-titanite assemblage overprints the coarse-grained clinopyroxene and amphibole,giving P-7 conditions of 8-9 kbar and 550 ℃ with an associated titanite age of ca.2050 Ma.A garnet-bearing amphibolite sample also from the core of the dome has peak P-T conditions of 7-8 kbar and 650-700 ℃,and texturally late titanite from this sample produces an age of ca.2060 Ma.Three additional samples were collected from the edges of the dome.A garnet-gedrite bearing felsic schist produces peak P-T conditions of 8-9 kbar and 650-700℃ on a clockwise P-T evolution.This sample has a U-Pb zircon age of ca.2775 Ma,which could date metamorphism or be the age of its volcaniclastic protolith.Texturally unconstrained titanite from the sample gives an age of ca.2040 Ma.A garnet-bearing amphibolite that occurs as a boudin within the felsic schist gives both zircon and titanite ages of ca.2050 Ma and has peak P-T conditions of 5-6 kbar and 650-700 ℃ on a near isobaric P-T path.An amphibolite dike,observed to cross-cut the felsic schist produces a zircon U-Pb age of ca.2760 Ma.Altogether this data suggests that the samples were metamorphosed in the Archean(ca.2775-2730 Ma)and again during the Transamazonian event.The most plausible explanation for this data is that dome-and-keel formation occurred in the Archean with migmatisation and high-temperature metamorphism occurring at this time.The Paleoproterozoic event is interpreted as a reactivation of the dome-and-keel formation structures,with Paleoproterozoic keels crosscutting Archean keels and producing metamorphic aureoles.The high radiogenic heat production and the presence of dense sedimentary successions in Archean terranes make dome-and-keel provinces a uniquely Archean feature,but they are susceptible to reworking,resulting in an enigmatic record of formation.     

Macroalgae blooms and δN in subtropical coastal lagoons from the Southeastern Gulf of California: Discrimination among agricultural, shrimp farm and sewage effluents

Macroalgae blooms of Gracilaria vermiculophylla, Hypnea spinella and Spyridia filamentosa have been found in coastal lagoons in the SE Gulf of California. Agriculture, livestock, shrimp and poultry farms and sewage contribute anthropogenic nitrogen to the systems. The δ¹⁵N of these sources, water column and macroalgae were studied in order to identify the N supply for macroalgae blooms. δ¹⁵N of three species of macroalgae (4.3-13.6‰) were enriched compared to the water column ( 3.7-6.8‰), probably because of fractioning from the macroalgae. δ¹⁵N of POM (1.4-10.3‰) was similar to the water column but the relationship was unclear. Depending on the site, macroalgae showed different δ¹⁵N values since some sites receive more or less influence from one given source of the associated watershed, which is reflected in the different δ¹⁵N values of the macroalgae of the same system and in the relative contributions of the sources.     

The application of caesium‐137 measurements to investigate floodplain deposition in a large semi‐arid catchment in Queensland,Australia: a low‐fallout environment

Floodplains comprise geomorphologically important sources and sinks for sediments and associated pollutants, yet the sedimentology of large dryland floodplains is not well understood. Processes occurring on such floodplains are often difficult to observe, and techniques used to investigate smaller perennial floodplains are often not practical in these environments. This study assesses the utility of ¹³⁷Cs inventory and depth‐profile techniques for determining relative amounts of floodplain sedimentation in the Fitzroy River, northeastern Australia; a 143 000 km² semi‐arid river system. Caesium‐137 inventories were calculated for floodplain and reference location bulk soil cores collected from four sites. Depth profiles of ¹³⁷Cs concentration from each floodplain site and a reference location were recorded. The areal density of ¹³⁷Cs at reference locations ranged from 13 to 978 Bq m^–2 (0–1367 Bq m^–2 at the 95% confidence interval), and the mean value ± 2 (standard error of the mean) was 436 ± 264 Bq m^–2, similar to published data from other Southern Hemisphere locations. Floodplain inventories ranged from 68 to 1142 Bq m^–2 (0–1692 Bq m^–2 at the 95% confidence interval), essentially falling within the range of reference inventory values, thus preventing calculation of erosion or deposition. Depth‐profiles of ¹³⁷Cs concentration indicate erosion at one site and over 66 cm of deposition at another since 1954. Analysis of ^239+240Pu concentrations in a depositional core substantiated the interpretation made from ¹³⁷Cs data, and depict a more tightly constrained peak in concentration. Average annual deposition rates range from 0 to 15 mm. The similarity between floodplain and reference bulk inventories does not necessarily indicate a lack of erosion or deposition, due to low ¹³⁷Cs fallout in the region and associated high measurement uncertainties, and a likely influence of gully and bank eroded sediments with no or limited adsorbed ¹³⁷Cs. In this low‐fallout environment, detailed depth‐profile data are necessary for investigating sedimentation using ¹³⁷Cs. Copyright © 2009 John Wiley & Sons, Ltd.     

Population Structure of Adult Blue Crabs, <Emphasis Type="Italic">Callinectes sapidus</Emphasis>, in Relation to Physical Characteristics in Barnegat Bay,New Jersey

Blue crabs (Callinectes sapidus) are an important species in coastal or lagoonal estuaries where adult population characteristics may differ as compared to drowned-river estuaries. Barnegat Bay, in southern New Jersey, is composed of two large embayments: one without and one with a salinity gradient. We tested the influence of physical characteristics on the abundance, sex ratio, and size of adult blue crabs and examined variation in measures of reproductive potential (e.g., sperm stores) in both sexes in Barnegat Bay from June to September, 2008–2009. Population structure was distinct between the embayments due to sex-specific responses to salinity: male abundance was negatively correlated with salinity whereas adult females were more abundant in high salinity because of proximity to Barnegat Inlet. This produced high sex ratios in low salinity areas and low sex ratios in high salinity areas. Summer was a growing season for adult males while in late summer-early fall, juvenile males recruited to the adult size class. The spawning season lasted from May to August and ovigerous females were concentrated near the inlets. Information on female sperm stores and ovarian development identified two cohorts of adult females: females that will spawn in the current summer and females that will not spawn until the following summer. Thus, not all adult females near the spawning grounds were members of the current spawning stock. This suggests that annual estimates of spawning stock size which overlook the proximity of females to spawning are overestimating the current spawning stock in Barnegat Bay and other estuaries.     

The size-frequency distribution of dormant Jupiter family comets

We estimate the total number and the slope of the size-frequency distribution (SFD) of dormant Jupiter family comets (JFCs) by fitting a one-parameter model to the known population. We first select 61 near-Earth objects (NEOs) that are likely to be dormant JFCs because their orbits are dynamically coupled to Jupiter [Bottke, W.F., Morbidelli, A., Jedicke, R., Petit, J., Levison, H.F., Michel, P., Metcalfe, T.S., 2002a. Icarus 156, 399-433]. Then, from the numerical simulations of Levison and Duncan [1997. Icarus 127, 13-32], we construct an orbit distribution model for JFCs in the NEO orbital element space. We assume an orbit-independent SFD for all JFCs, the slope of which is our unique free parameter. Finally, we compute observational biases for dormant JFCs using a calibrated NEO survey simulator [Jedicke, R., Morbidelli, A., Spahr, T., Petit, J., Bottke, W.F., 2003. Icarus 161, 17-33]. By fitting the biased model to the data, we estimate that there are ∼75 dormant JFCs with H<18 in the NEO region and that the slope of their cumulative SFD is −1.5±0.3. Our slope for the SFD of dormant JFCs is very close to that of active JFCs as determined by Weissman and Lowry [2003. Lunar Planet. Sci. 34. Abstract 2003]. Thus, we argue that when JFCs fade they are likely to become dormant rather than to disrupt and that the fate of faded comets is size-independent. Our results imply that the size distribution of the JFC progenitors—the scattered disk trans-neptunian population—either (i) has a similar and shallow SFD or (i^′) is slightly steeper and physical processes acting on the comets in a size-dependent manner creates the shallower active comet SFD. Our measured slope, typical of collisionally evolved populations with a size-dependent impact strength [Benz, W., Asphaug, E., 1999. Icarus 142, 5-20], suggests that scattered disk bodies reached collisional equilibrium inside the protoplanetary disk prior to their removal from the planetary region.     

The effects of viewing angle on the inference of magnetic shear in preflare active regions

The magnetic shear at a point within an active region field configuration can be defined (Hagyard et al., 1984b) as the difference in angle between the observed photospheric transverse field and that of a reference potential field calculated using the observed line-of-sight field as a boundary condition. Using analytic models for non-potential (but force-free) fields representative of preflaring active regions, we calculate the degree of magnetic shear along the magnetic neutral line that such fields would exhibit, as a function of the location and orientation of the active region on the solar disk. We find that, except for regions close to disk center, the position of the inferred neutral line (zero line-of-sight field) is significantly different from the actual neutral line (zero radial field), and that the calculated reference potential field also varies significantly with the position of the region. Thus the inferred degree of shear can vary significantly with the position and orientation of the region, due to (a) straightforward geometric projection effects, (b) the shift of the inferred neutral line relative to its true position, and (c) variations in the reference potential field. The significance of these results for flare prediction is considered.Presidential Young Investigator.