Southeast Atlantic Research Articles

Global status of groundfish stocks

AbstractWe review the status of groundfish stocks using published scientific assessments for 349 individual stocks constituting 90% of global groundfish catch. Overall, average stock abundance is increasing and is currently above the level that would produce maximum sustainable yield (MSY). Fishing pressure for cod‐like fishes (Gadiformes) and flatfishes (Pleuronectiformes) was, for several decades, on average well above levels associated with MSY, but is now at or below the level expected to produce MSY. In contrast, fishing pressure for rockfishes (Scorpaeniformes) decreased from near MSY‐related levels in the mid‐1990s, and since the mid‐2000s has remained on average at only one third of MSY‐related levels. Regions with the most depressed groundfish stocks are the Northwest Atlantic and the Pacific coast of South America, while stocks from the Northeast and Eastern Central Pacific, Northeast Atlantic, Southeast Atlantic and Southwest Pacific tend to have greatest average abundance relative to MSY‐based reference points. In the most recent year available for each stock, the catch was only 61% of MSY. Equilibrium yield curves indicate that 76% of global potential groundfish yield could be achieved using current estimates of fishing pressure. 15% of this is lost by excess fishing pressure, 67% results from lower than optimal fishing pressure on healthy stocks and 18% is lost from stocks currently overfished but rebuilding. Thus, there is modest opportunity to increase catch of global groundfish fisheries by reducing overfishing on some stocks, but more by increasing harvest on others. However, there may be other reasons not to fully exploit these stocks.

Spatiotemporal Heterogeneity of Aerosol and Cloud Properties Over the Southeast Atlantic: An Observational Analysis

AbstractThe southeast Atlantic has expansive aerosol plumes overlying clouds for a third of each year. Aerosol optical depths (AODs) were measured from the airborne Sun photometer and lidar during the 2016 NASA ObseRvations of Aerosols above CLouds and their intEractionS (ORACLES) field campaign. We compare these measurements with one another and with collocated Moderate Resolution Imaging Spectroradiometer (MODIS) observations at native spatial resolutions using <15‐min and 3‐h temporal collocation criteria. We find better statistical relationships for the <15‐min temporal resolution, indicating that AODs in the southeast Atlantic commonly vary below three‐hourly temporal scales over MODIS spatial resolutions. We also use the airborne Solar Spectral Flux Radiometer (SSFR) to conduct the first comprehensive evaluation of attenuation‐corrected below‐aerosol cloud optical depths (CODs) from MODIS and the Spinning Enhanced Visible and Infrared Imager (SEVIRI). MODIS COD retrievals improve their agreement with the SSFR when accounting for overlying aerosol attenuation whereas SEVIRI CODs are mostly underestimated.

Regional flow conditions associated with stratocumulus cloud-eroding boundaries over the southeast Atlantic

AbstractLarge, abrupt clearing events have been documented in the marine stratocumulus cloud deck over the subtropical Southeast Atlantic Ocean. In these events, clouds are rapidly eroded along a line hundreds–to–thousands of kilometers in length that generally moves westward away from the coast. Because marine stratocumulus clouds exert a strong cooling effect on the planet, any phenomenon that acts to erode large areas of low clouds may be climatically important. Previous satellite-based research suggests that the cloud-eroding boundaries may be caused by westward-propagating atmospheric gravity waves rather than simple advection of the cloud. The behavior of the coastal offshore flow, which is proposed as a fundamental physical mechanism associated with the clearing events, is explored using the Weather Research and Forecasting model. Results are presented from several week-long simulations in the month of May when cloud-eroding boundaries exhibit maximum frequency. Two simulations cover periods containing multiple cloud-eroding boundaries (active periods), and two other simulations cover periods without any cloud-eroding boundaries (null periods). Passive tracers and an analysis of mass flux are used to assess the character of the diurnal west-African coastal circulation. Results indicate that the active periods containing cloud-eroding boundaries regularly experience stronger and deeper nocturnal offshore flow from the continent above the marine boundary layer, compared to the null periods. Additionally, we find that the boundary layer height is higher in the null periods than in the active periods, suggesting that the active periods are associated with areas of thinner clouds that may be more susceptible to cloud erosion.

Impact of the variability in vertical separation between biomass burning aerosols and marine stratocumulus on cloud microphysical properties over the Southeast Atlantic

Abstract. Marine stratocumulus cloud properties over the Southeast Atlantic Ocean are impacted by contact between above-cloud biomass burning aerosols and cloud tops. Different vertical separations (0 to 2000 m) between the aerosol layer and cloud tops were observed on six research flights in September 2016 during the NASA ObseRvations of Aerosols above CLouds and their intEractionS (ORACLES) field campaign. There were 30 contact profiles, where an aerosol layer with aerosol concentration (Na) > 500 cm−3 was within 100 m of cloud tops, and 41 separated profiles, where the aerosol layer with Na > 500 cm−3 was located more than 100 m above cloud tops. For contact profiles, the average cloud droplet concentration (Nc) in the cloud layer was up to 68 cm−3 higher, the effective radius (Re) up to 1.3 µm lower, and the liquid water content (LWC) within 0.01 g m−3 compared to separated profiles. Free-tropospheric humidity was higher in the presence of biomass burning aerosols, and contact profiles had a smaller decrease in humidity (and positive buoyancy) across cloud tops with higher median above-cloud Na (895 cm−3) compared to separated profiles (30 cm−3). Due to droplet evaporation from entrainment mixing of warm, dry free-tropospheric air into the clouds, the median Nc and LWC for contact profiles decreased with height by 21 and 9 % in the top 20 % of the cloud layer. The impact of droplet evaporation was stronger during separated profiles as a greater decrease in humidity (and negative buoyancy) across cloud tops led to greater decreases in median Nc (30 %) and LWC (16 %) near cloud tops. Below-cloud Na was sampled during 61 profiles, and most contact profiles (20 out of 28) were within high-Na (> 350 cm−3) boundary layers, while most separated profiles (22 out of 33) were within low-Na (< 350 cm−3) boundary layers. Although the differences in below-cloud Na were statistically insignificant, contact profiles within low-Na boundary layers had up to 34.9 cm−3 higher Nc compared to separated profiles. This is consistent with a weaker impact of droplet evaporation in the presence of biomass burning aerosols within 100 m above cloud tops. For contact profiles within high-Na boundary layers, the presence of biomass burning aerosols led to higher below-cloud Na (up to 70.5 cm−3) and additional droplet nucleation above the cloud base along with weaker droplet evaporation. Consequently, the contact profiles in high-Na boundary layers had up to 88.4 cm−3 higher Nc compared to separated profiles. These results motivate investigations of aerosol–cloud–precipitation interactions over the Southeast Atlantic since the changes in Nc and Re induced by the presence of above-cloud biomass burning aerosols are likely to impact precipitation rates, liquid water path, and cloud fraction, and modulate closed-to-open-cell transitions.

Analyzing Spatio-temporal Land Cover Dynamics in an Atlantic Forest Portion Using Unsupervised Change Detection Techniques

Over the past decades, the Southeast Atlantic Forest in Paraiba do Sul River Valley has suffered intense deforestation and human disturbances. Due to the Atlantic Forest biodiversity and the economic relevance of such a region in Brazil, spatial-temporal analyses are of crucial importance to protect the forest, as well as to support economic decision-making of public and private agents. In this context, the use of change detection techniques applied to remote sensing imagery arises as a powerful tool to track and map the Earth’s surface transformations. Therefore, this work investigates the effectiveness and practical feasibility of distinct unsupervised change detection approaches when they are applied to reveal the spatial-temporal dynamics in Paraiba do Sul River Valley across the last four decades. Different change detection approaches such as Change Vector Analysis (CVA), a K-Means and Principal Component Analysis (PCA-KM) framework, and a Alternating Sequential Filtering (ASF) based process were taken and properly tuned to cope with Landsat image series. The analysis of the results revealed a permanent land cover change rate over the last decades. Moreover, these changes do not necessary occur in the same locations, as it was confirmed the existence of successive modifications in original coverage of the study area. Another observed aspect is that the simplest technique for detecting changes, CVA, turned out to be the best approach to map the changes in the examined region.

Hydropower under climate uncertainty: Characterizing the usable capacity of Brazilian, Colombian and Peruvian power plants under climate scenarios

Hydropower may be a low-carbon option to increase power generation in developing countries, but these countries are some of the most vulnerable to climate change. Climate change can affect hydropower generation through changes in the timing and magnitude of precipitation, rising temperatures, and glacier mass changes. Evaluating climate impacts on hydropower generally requires detailed local input data and hydrological models, which may not be available in many developing nations. Nevertheless, the need to understand the impacts is essential for the developing world. Here we present a modeling framework that relies on remotely sensed and global gridded datasets forced by an ensemble of 21 general circulation models (GCMs) under two representative concentration pathways (RCPs) to evaluate climate-induced impacts on hydropower through the 21st century. We include 134 hydropower plants (>100 MW), representing 42% of hydropower installed capacity in South America, across five regions of Brazil, Colombia, and Peru. Our results suggest the median monthly usable capacity would increase for Colombia (+2.6% to +8.4% for RCP 4.5 and 8.5, respectively) and Peru (+6.7% to +9.3% for RCP 4.5 and 8.5, respectively) by 2100 relative to the late 20th century. For Brazil, we observe a mix of reductions and increases in usable capacity. While our results suggest potential reductions for the dry season usable capacity in the Parana, Paraguay, and Southeast Atlantic regions of Brazil, we also observe slight increases in usable capacity during the rainy months for all its regions. These results can help inform future planning decisions and potential interconnections between the three countries. Additionally, the proposed framework can contribute to an increased capability to evaluate climate-induced risks to power systems in developing countries, where data and computation resources can be limited.

The CLoud–Aerosol–Radiation Interaction and Forcing: Year 2017 (CLARIFY-2017) measurement campaign

Abstract. The representations of clouds, aerosols, and cloud–aerosol–radiation impacts remain some of the largest uncertainties in climate change, limiting our ability to accurately reconstruct past climate and predict future climate. The south-east Atlantic is a region where high atmospheric aerosol loadings and semi-permanent stratocumulus clouds are co-located, providing an optimum region for studying the full range of aerosol–radiation and aerosol–cloud interactions and their perturbations of the Earth's radiation budget. While satellite measurements have provided some useful insights into aerosol–radiation and aerosol–cloud interactions over the region, these observations do not have the spatial and temporal resolution, nor the required level of precision to allow for a process-level assessment. Detailed measurements from high spatial and temporal resolution airborne atmospheric measurements in the region are very sparse, limiting their use in assessing the performance of aerosol modelling in numerical weather prediction and climate models. CLARIFY-2017 was a major consortium programme consisting of five principal UK universities with project partners from the UK Met Office and European- and USA-based universities and research centres involved in the complementary ORACLES, LASIC, and AEROCLO-sA projects. The aims of CLARIFY-2017 were fourfold: (1) to improve the representation and reduce uncertainty in model estimates of the direct, semi-direct, and indirect radiative effect of absorbing biomass burning aerosols; (2) to improve our knowledge and representation of the processes determining stratocumulus cloud microphysical and radiative properties and their transition to cumulus regimes; (3) to challenge, validate, and improve satellite retrievals of cloud and aerosol properties and their radiative impacts; (4) to improve the impacts of aerosols in weather and climate numerical models. This paper describes the modelling and measurement strategies central to the CLARIFY-2017 deployment of the FAAM BAe146 instrumented aircraft campaign, summarizes the flight objectives and flight patterns, and highlights some key results from our initial analyses.

Molecular data reshape our understanding of the life cycles of three digeneans (Monorchiidae and Gymnophallidae) infecting the bivalve, Donax variabilis: it's just a facultative host!

The coquina, Donax variabilis, is a known intermediate host of monorchiid and gymnophallid digeneans. Limited morphological criteria for the host and the digeneans’ larval stages have caused confusion in records. Herein, identities of coquinas from the United States (US) Atlantic coast were verified molecularly. We demonstrate that the current GenBank sequences for D. variabilis are erroneous, with the US sequence referring to D. fossor. Two cercariae and three metacercariae previously described in the Gulf of Mexico and one new cercaria were identified morphologically and molecularly, with only metacercariae occurring in both hosts. On the Southeast Atlantic coast, D. variabilis’ role is limited to being a facultative second intermediate host, and D. fossor, an older species, acts as both first and second intermediate hosts. Sequencing demonstrated 100% similarities between larval stages for each of the three digeneans. Sporocysts, single tail cercariae, and metacercariae in the incurrent siphon had sequences identical to those of monorchiid Lasiotocus trachinoti, for which we provide the complete life cycle. Adults are not known for the other two digeneans, and sequences from their larval stages were not identical to any in GenBank. Large sporocysts, cercariae (Cercaria choanura), and metacercariae in the coquinas’ foot were identified as Lasiotocus choanura (Hopkins, 1958) n. comb. Small sporocysts, furcocercous cercariae, and metacercariae in the mantle were identified as gymnophallid Parvatrema cf. donacis. We clarify records wherein authors recognized the three digenean species but confused their life stages, and probably the hosts, as D. variabilis is sympatric with cryptic D. texasianus in the Gulf of Mexico.

Научно-поисковые исследования и перспективы развития отечественного океанического рыболовства в Атлантике и Юго-Восточной части Тихого океана

The article provides a brief description of the activities of scientific research
 studies of AtlantNIRO to provide the domestic fishing fleet with a raw
 material base in the oceanic regions. The main stages of the opening of
 fishing areas and new fishing facilities in the North-West, Central, South-
 West and South-East Atlantic and in the South-East Pacific are described.
 It is emphasized that at the present time, in the conditions of a changing
 climate, it is impossible to stop expeditionary work in order to monitor fish
 stocks and their distribution in the open areas of the ocean.

Dissolved neodymium and hafnium isotopes and rare earth elements in the Congo River Plume: Tracing and quantifying continental inputs into the southeast Atlantic

The Congo River is the second largest river by discharge in the world and a major source of element inputs into the South Atlantic Ocean. Yet, the element fluxes and transport mechanisms across and beyond its estuary and their impacts on the marine distribution and cycling of many major and trace elements are not well understood. We present the first combined dissolved neodymium (Nd) and hafnium (Hf) isotope and rare earth element (REE) concentration distributions following the Congo River plume along its flow path off the West African coast and along a connected offshore latitudinal section at 3°S. The Congo River freshwater itself is characterized by extraordinarily high Nd and Hf concentrations of up to 4000 pmol/kg and 54 pmol/kg, and by Nd (εNd) and Hf (εHf) isotope compositions that range between −15.6 and −16.4 and between 0.35 and −1.4, respectively. Our near- and offshore data indicate that at salinities above 23 conservative mixing of Congo-derived Nd and Hf concentrations and isotopic signatures with ambient surface seawater occurs for at least 1000 km to the northwest of the river mouth. This demonstrates a large spatial extent of the influence of the Congo plume on trace metal distributions in the eastern south Atlantic surface waters. A comparison between dissolved Nd and Hf fluxes from the Congo River and the shelf zone estimated based on radium isotope compositions indicate that release from Congo-derived particulate phases likely balances strong estuarine REE and Hf removal in the low salinity zone. The combined riverine and shelf zone flux for Nd is almost twice as high as that estimated for the Amazon River, despite that the Amazon discharge is about five times higher than that of the Congo River. Even the offshore Nd flux estimated for the 3 °S transect based on radium isotope compositions still corresponds to ∼40% of the Congo-shelf-zone flux and reaches 150 ± 50 Mg/year for Nd. Moreover, intermediate waters below the plume are strongly affected by exchange with particulate inputs from the Congo River given that Nd isotope signatures are inconsistent with values expected from large-scale water mass mixing and instead support unradiogenic Nd release either from sinking or deposited Congo-derived detrital material. Deep and bottom water isotopic signatures are also slightly affected by interaction with particles and benthic Nd release.

Direct and semi-direct radiative forcing of biomass-burning aerosols over the southeast Atlantic (SEA) and its sensitivity to absorbing properties: a regional climate modeling study

Abstract. Simulations are performed for the period 2000–2015 by two different regional climate models, ALADIN and RegCM, to quantify the direct and semi-direct radiative effects of biomass-burning aerosols (BBAs) in the southeast Atlantic (SEA) region. Different simulations have been performed using strongly absorbing BBAs in accordance with recent in situ observations over the SEA. For the July–August–September (JAS) season, the single scattering albedo (SSA) and total aerosol optical depth (AOD) simulated by the ALADIN and RegCM models are consistent with the MACv2 climatology and MERRA-2 and CAMS-RA reanalyses near the biomass-burning emission sources. However, the above-cloud AOD is slightly underestimated compared to satellite (MODIS and POLDER) data during the transport over the SEA. The direct radiative effect exerted at the continental and oceanic surfaces by BBAs is significant in both models and the radiative effects at the top of the atmosphere indicate a remarkable regional contrast over SEA (in all-sky conditions), with a cooling (warming) north (south) of 10 ∘S, which is in agreement with the recent MACv2 climatology. In addition, the two models indicate that BBAs are responsible for an important shortwave radiative heating of ∼0.5–1 K per day over SEA during JAS with maxima between 2 and 4 km a.m.s.l. (above mean sea level). At these altitudes, BBAs increase air temperature by ∼0.2–0.5 K, with the highest values being co-located with low stratocumulus clouds. Vertical changes in air temperature limit the subsidence of air mass over SEA, creating a cyclonic anomaly. The opposite effect is simulated over the continent due to the increase in lower troposphere stability. The BBA semi-direct effect on the lower troposphere circulation is found to be consistent between the two models. Changes in the cloud fraction are moderate in response to the presence of smoke, and the models differ over the Gulf of Guinea. Finally, the results indicate an important sensitivity of the direct and semi-direct effects to the absorbing properties of BBAs. Over the stratocumulus (Sc) region, DRE varies from +0.94 W m−2 (scattering BBAs) to +3.93 W m−2 (most absorbing BBAs).

An upwelling area as a hot spot for mercury biomonitoring in a climate change scenario: A case study with large demersal fishes from Southeast Atlantic (SE-Brazil)

Data concerning the monomethylmercury (MeHg) bioaccumulation in marine biota from Southeast Atlantic Ocean are scarce. This study purchased large specimens of demersal fishes from an upwelling region: Warsaw grouper (Epinephelus nigritus), Dusky grouper (Epinephelus marginatus) and Namorado sandperch (Pseudopercis numida). The authors addressed the bioaccumulation and toxicokinetic of mercury in fish organs, and the toxicological risk for human consumption of this metal in the muscle tissues accessed. Additionally, the present study discussed the possible implications of shifts in key variables of the environment related to a climate-changing predicted scenario, to the mercury biomagnification in a tropical upwelling system. The muscle was the main stock of MeHg, although the highest THg concentrations have been found in liver tissue. Regarding the acceptable maximum level (ML = 1 mg kg−1), E. nigritus and E. marginatus showed 22% of the samples above this limit. Concerning P. numida, 77% were above 0.5 mg kg−1, but below the ML. The %MeHg in liver and muscle showed no significative correlations, which suggest independent biochemical pathways to the toxicokinetic of MeHg, and constrains the indirect assessment of the mercury contamination in the edible tissue by the liver analyses. The present study highlights the food web features of a tropical upwelling ecosystem that promote mercury biomagnification. Additionally, recent studies endorse the enhancement of upwelling phenomenon due to the climate global changes which boost the pumping of mercury enriched water to the oceanic upper layer. Therefore, the upwelling areas might be hot spots for MeHg monitoring in marine biota.

Sightings of southern right whales (Eubalaena australis) in Namibian waters, 1971-1999

Southern right whales were originally abundant in Namibian waters in winter and spring. They were either eradicated from the region ordriven to extremely low numbers more than a century ago. Since 1971, 36 incidental sightings and three aerial surveys confirm the regularpresence of the species within its historical calving range, between June and December. Calving has been recorded in four successive yearsand at least 10 calves were born in the area between 1996 and 1999, confirming the existence of a small established breeding population.This represents a northward extension of the hitherto known modern regular calving range in the South East Atlantic Ocean by more than1,000km.

Daytime aerosol optical depth above low-level clouds is similar to that in adjacent clear skies at the same heights: airborne observation above the southeast Atlantic

Abstract. To help satellite retrieval of aerosols and studies of their radiative effects, we demonstrate that daytime aerosol optical depth over low-level clouds is similar to that in neighboring clear skies at the same heights. Based on recent airborne lidar and sun photometer observations above the southeast Atlantic, the mean aerosol optical depth (AOD) difference at 532 nm is between 0 and −0.01, when comparing the cloudy and clear sides, each up to 20 km wide, of cloud edges. The difference is not statistically significant according to a paired t test. Systematic differences in the wavelength dependence of AOD and in situ single scattering albedo are also minuscule. These results hold regardless of the vertical distance between cloud top and aerosol layer bottom. AOD aggregated over ∼2∘ grid boxes for each of September 2016, August 2017 and October 2018 also shows little correlation with the presence of low-level clouds. We posit that a satellite retrieval artifact is entirely responsible for a previous finding of generally smaller AOD over clouds (Chung et al., 2016), at least for the region and time of our study. Our results also suggest that the same values can be assumed for the intensive properties of free-tropospheric biomass-burning aerosol regardless of whether clouds are present below.

Mid-level clouds are frequent above the southeast Atlantic stratocumulus clouds

Abstract. Shortwave-absorbing aerosols seasonally overlay extensive low-level stratocumulus clouds over the southeast Atlantic. While much attention has focused on the interactions between the low-level clouds and the overlying aerosols, few studies have focused on the mid-level clouds that also occur over the region. The presence of mid-level clouds over the region complicates the space-based remote-sensing retrievals of cloud properties and the evaluation of cloud radiation budgets. Here we characterize the mid-level clouds over the southeast Atlantic using lidar- and radar-based satellite cloud retrievals and observations collected in September 2016 during the ORACLES (ObseRvations of Aerosols above CLouds and their intEractionS) field campaign. We find that mid-level clouds over the southeast Atlantic are relatively common, with the majority of the clouds occurring between altitudes of 5 and 7 km and at temperatures between 0 and −20 ∘C. The mid-level clouds occur at the top of a moist mid-tropospheric smoke-aerosol layer, most frequently between August and October, and closer to the southern African coast than farther offshore. They occur more frequently during the night than during the day. Between July and October, approximately 64 % of the mid-level clouds had a geometric cloud thickness less than 1 km, corresponding to a cloud optical depth of less than 4. A lidar-based depolarization–backscatter relationship for September 2016 indicates that the mid-level clouds are liquid-only clouds with no evidence of the existence of ice. In addition, a polarimeter-derived cloud droplet size distribution indicates that approximately 85 % of the September 2016 mid-level clouds had an effective radius less than 7 µm, which could further discourage the ability of the clouds to glaciate. These clouds are mostly associated with synoptically modulated mid-tropospheric moisture outflow that can be linked to the detrainment from the continental-based clouds. Overall, the supercooled mid-level clouds reduce the radiative cooling rates of the underlying low-altitude cloud tops by approximately 10 K d−1, thus influencing the regional cloud radiative budget.

Namibia's way to Marine Spatial Planning – Using existing practices or instigating its own approach?

The territorial waters and EEZ of Namibia are part of the Benguela Current Large Marine Ecosystem in the South-East Atlantic. Growing demands and conflicts emerge although the area is not as intensely used as marine areas elsewhere. Namibia has chosen Marine Spatial Planning (MSP) as an integrated approach to facilitate sustainable ocean development and improved ocean governance. The paper explores the reality of the Namibian MSP process to date by investigating two guiding research questions: (1) What makes the Namibian approach to MSP distinct? and (2) What are the opportunities and difficulties of the Namibian MSP process in that particular context? The country's approach to MSP features a series of distinct attributes, not least due to its unique environmental and socio-economic context. Namibian MSP is highly precautionary and forward-looking given the relatively low intensity of current uses, has a strong ecosystem-based perspective due to the fairly pristine environment, is driven by a social equity and distributive justice agenda, and features a strong collaborative process governance. Whilst challenges such as limited financial resources, lacking legislation and weak links to broader ocean governance exist, the MSP process, which was linked to a systematic conservation planning process from the outset, has however resulted in a clear framework for the development of the first marine plan.

Quantifying climate, streamflow, and watershed control on water quality across Southeastern US watersheds

Identification of the key variables that influence spatial variation in stream water quality is crucial for designing sustainable water management strategies. In this study, we investigated the key variables that influence the spatial variability of stream of water quality, across multiple watersheds. This study uses water quality data collected over 19 years for 59 watersheds located in the Southeast Atlantic region of the United States, which includes the states of North Carolina, South Carolina, and Georgia. A conceptual modeling framework was developed to understand the linkage between the long-term mean water quality constituents (Total nitrogen, Total phosphorus, Turbidity, and pH) and the watershed characteristics (e.g., topography, land use/cover, soil type), streamflow data, and climatic variables (precipitation and temperature). The modeling results suggest that not only anthropogenic variables influence the mean water quality constituents, but other watershed characteristics, such as soil properties, have a significant impact. The natural watershed characteristics explain most of the spatial variability in the mean Turbidity and pH values in streams. The modeling results also suggest that once land use and soil properties are considered, watershed topography has a limited role to explain the variation in the mean water quality. Overall, the developed watershed models can be used to forecast stream water-quality responses to future land use, climate, soil, and land management changes within the study area.

Underwaterwriting: from theory to empiricism in regional mortgage markets in the U.S.

This article provides the theoretical foundation for the concept of “Underwaterwriting,” which can be understood as various informational and institutional limitations related to environmental exposure and climate change impacts—specifically flooding and sea level rise inundation—shaping firm participation in mortgage markets. Underwaterwriting suggests that the unevenness of scientific knowledge and local soft information, as well as the institutional barriers for the utilization of that information, could result in determinations of risk that may not accurately reflect long-term asset performance or credit loss. These informational asymmetries may result in assignments of risk that reflect a degree of arbitrariness or inaccuracy that may operate to strand assets and shed or increase market share in ways that are inefficient and may otherwise lead to negative public externalities. Consistent with this theory, this article provides evidence that concentrated local lenders are transferring risk in high-risk coastal geographies in the Southeast Atlantic and Gulf Coasts (U.S.) through increased securitization of mortgages. These findings provide an impetus for supporting more robust analysis of climate-risk in light of forthcoming accounting rules that require an upfront accounting of forward-looking credit losses.

Identification of four new Kudoa spp. (Myxozoa: Myxosporea: Multivalvulida) in commercial fishes collected from South China Sea, Atlantic Ocean, and Bering Sea by integrated taxonomic approach.

Members of the myxosporean genus Kudoa are defined as having a myxospore with four or more shell valves (SVs) and a corresponding number of polar capsules (PCs). Here, we employed integrated taxonomic approaches to four kudoid isolates from Acentrogobius chlorostigmatoides and Konosirus punctatus from the South China Sea, off Guangdong, Pentanemus quinquarius from the Southeast Atlantic Ocean, off West African coast, and Atheresthes stomias from the Bering Sea, off Alaska, and concluded that all these kudoids were novel species, named Kudoa acentrogobia n. sp., Kudoa guangdongensis n. sp., Kudoa iidae n. sp., and Kudoa aburakarei n. sp., respectively. Kudoa guangdongensis n. sp., forming pseudocysts in the trunk muscle myofibers of K. punctatus, had large-sized tripod myxospores with three wing-like SV extensions and three PCs (one prominent PC and two rudimentary PCs). Phylogenetic analyses based on the 18S and 28S ribosomal RNA gene (rDNA) demonstrated its affinity to the genus Kudoa, not to Unicapsula characterized by a myxospore with one prominent PC and two rudimentary PCs, suggesting the atypical nature of this new species in the context of myxospore morphology. Three other kudoid isolates had four SVs and PCs in a semi-quadrated, ray-like, or cruciform myxospore, respectively, forming pseudocysts in the trunk muscle myofibers. Kudoa iidae n. sp. forming pseudocysts in the muscles of P. quinquarius from Southeast Atlantic Ocean had unique myxospores with ray-like form, showing close morphological resemblance to Kudoa rayformis, which were recorded from the muscle of Scomberomorus sierra from the Pacific Ocean off Panama. These two species had a phylogenetic relationship of morphological convergence, evolving separately in different sea areas. It is fairly difficult to differentiate K. acentrogobia n. sp. and K. aburakarei n. sp., prevalent in their host fishes, from kudoid species with similar myxospore morphology (e.g., Kudoa nova and Kudoa thyrsites, respectively), but distinct in phylogeny from known Kudoa spp. Combined taxonomic identification of multivalvulid myxosporeans based on both morphological criteria of isolated myxozoans and their molecular characterization could disclose their real biodiversity and phylogeny.

On the diversity of Terebellides (Annelida, Trichobranchidae) in West Africa,seven new species and the redescription of T. africana Augener, 1918 stat. prom.

The actual diversity of Terebellides (Annelida; Trichobranchidae) in the South East Atlantic Ocean remains largely unknown. Only two species have been reported to date, T. stroemii Sars, 1835 and T. jorgeni Hutchings, 2007. The revision of specimens collected during the Atlantide and Galathea oceanographic cruises in the Atlantic coast of Africa, along with new materials obtained during monitoring surveys off Gabon, Congo and Angola, has allowed us to describe seven new species: T. augeneri sp. nov., T. congolana sp. nov., T. fauveli sp. nov., T. kirkegaardi sp. nov., T. longiseta sp. nov., T. nkossa sp. nov. and T. ramili sp. nov. Moreover, the type material of Terebellides stroemii var. africana Augener, 1918 is redescribed and the variety raised to species. All taxa are morphologically characterised and compared with species described or reported in world seas, particularly from the Atlantic Ocean. The presence of T. stroemii in Africa and the validity of the thoracic uncini as taxonomic character is discussed and a key to all species of Terebellides described from the South Atlantic Ocean is provided.