An evaluation of progress in implementing ecosystem-based management of fisheries in 33 countries

The performance of 33 countries was evaluated for ecosystem-based management (EBM) of fisheries in three fields (principles, criteria and implementation) using quantitative ordination including uncertainty. No country rated overall as ‘good’, only four countries were ‘adequate’, while over half received ‘fail’ grades. A few developing countries performed better than many developed nations. Two case studies test the method. In Indonesia, Raja Ampat and Papua, rated similar to the national evaluation, but better performance might follow successful implementation of a planned EBM initiative. A workshop in Australia rated regional fisheries managed by New South Wales 20% lower for EBM than federally managed fisheries.     

Late Glacial and Holocene avulsions of the Rio Pastaza Megafan (Ecuador–Peru): frequency and controlling factors

The geomorphological study by means of remote sensing imagery of the Rio Pastaza Megafan (Ecuador and northern Peru) reveals the traces of numerous avulsions. One hundred and eight avulsion sites have been defined. The location of these sites, the available radiocarbon ages as well as historical maps of the seventeenth century, enable us to propose an evolution history of the migration and avulsions of the Rio Pastaza since the Last Glacial Maximum. The first avulsions of the Río Pastaza occurred after the LGM in a zone close to and roughly parallel to the sudandean front, where the developed avulsion gave a distributive pattern to the ancient stream of the Río Pastaza in an area located between the modern Río Morona and Pastaza, where they caused the Rio Pastaza to develop a fan-like distributary pattern. This is interpreted as a response to thrust-related forelimb tilt, progressively shifting eastward the Rio Pastaza and the apex of the megafan. This sequence of events ended with the Great Diversion of the Rio Pastaza towards the modern Rios Corrientes and Tigre. Avulsions occurred in the Tigre-Corrientes Area between 9200 and 8,500 years Cal BP. Afterwards, the Río Pastaza was diverted to its present-day north–south course. This last significant avulsion occurred before AD 1691. In the area located between the modern Río Morona and Pastaza, avulsion frequency—probably overestimated—ranges between 100 and 200 years. In the Ríos Tigre and Corrientes area, avulsion frequency—probably underestimated—ranges from 300 to 400 years. Regional tectonics is likely to have triggered most of the avulsions in the Morona Pastaza area but its influence is restricted to this area. The factors controlling the avulsions in the Tigre-Corrientes area are less clear because the frequently described “hydrologic”-driven avulsion as observed in areas characterized by contrasted hydrologic cycles are inconsistent with the characteristics of the hydrologic cycles of the Rio Pastaza.     

Efficient Imaging Strategies For Next-Generation Radio Arrays

The performance goals of the Square Kilometre Array (SKA) are such that major departures from prior practice for imaging interferometer arrays are required. One class of solutions involves the construction of large numbers of stations, each composed of one or more small antennas. The advantages of such a “large-N” approach are already documented, but attention has recently been drawn to scaling relationships for SKA data processing that imply excessive computing costs associated with the use of small antennas. In this paper we examine the assumptions that lead to such scaling laws, and argue that in general they are unlikely to apply to the SKA situation. A variety of strategies for SKA imaging which exhibit better scaling behaviour are discussed. Particular attention is drawn to field of view issues, and the possibility of using weighting functions within an advanced correlator system to precisely control the field-of-view.     

Forebulge dynamics and environmental control in Western Amazonia: The case study of the Arch of Iquitos (Peru)

The Iquitos Arch corresponds to a broad topographic high in the Western Amazonia. Morphostructural and geophysical data and flexural modeling show that the Iquitos Arch is the present-day forebulge of the Northwestern Amazonian foreland basin. A detailed tectono-sedimentary study of the Neogene and Quaternary deposits of the Iquitos area has been carried out in order to circumscribe the timing of the forebulge uplift and its environmental consequences. The Neogene and Quaternary sedimentary succession of the Iquitos Arch consists of six formations that evolved from tidal to fluvial environments. The first three formations exhibit Late Miocene gliding features and synsedimentary normal faults. Such soft-sediment deformations bear witness to tectonic activity ascribed to the growth of the forebulge. Regional erosive surfaces that separate the Neogene and Quaternary formations recorded the progressive forebulge emersion and the evolution of Amazonian drainage system. This uplift is related to an increase in tectonic activity within the Andes, which has provoked the eastern propagation of the orogenic wedge and caused an orogenic loading stage in the Amazonian foreland basin system. The emersion of the forebulge induced the retreat of the Pebas “marine megalake” nearby the Iquitos area and consequently caused important environmental changes in the Amazonian basin. From the end of the Late Miocene to the Pliocene, the forebulge acted as a barrier inducing the deposition of fluvial deposits in the forebulge depozone and the deposition of the “White Sand” deposits in the backbulge depozone. Since about 6 Ma, the forebulge is incised and crossed over by the modern Amazon River. The Iquitos forebulge is still growing as shown by the faulted Holocene terrace deposits.     

Geomorphic evidence of active deformation and uplift in a modern continental wedge-top–foredeep transition: Example of the eastern Ecuadorian Andes

The eastern Ecuadorian Andes appear as a fold-and-thrust belt adjacent to a continental foredeep represented by one of the world's largest tropical alluvial megafans, the Pastaza megafan, debouching into the Amazonian lowland. The apex of the Pliocene–Pleistocene megafan situated in the present-day wedge top (Subandean Zone) has been cut by an erosion surface, the western part of which has been uplifted of 500 m along the frontal thrust, forming a poorly dissected plateau, the Mera plateau. This erosion surface erased most of the previous fluvial landscape but preserved a large thrust-related anticlinal hinge deforming less erodible underlying strata, the Mirador fold and smaller-sized anticlines. This surface has been then incised by two antecedent major rivers, the Pastaza and the Napo, and few tributaries. The plateau edge is marked by a series of large scale gently sloping landslides clustered along a 70 km long concave eastward line associated with the frontal thrust fault. The newly formed immature rivers issued from the landslides or sourced within east-dipping remnants of the erosion surface downstream of the landslide line constitute the greatest part of the streams feeding the Ecuadorian Amazonian basin. At 70 to 100 km from the landslide line, the drainage abruptly changes from highly immature to mature with a well-defined hinge line representing the outer limit of landslide and tectonic control. The diversions of the Pastaza River indicate ongoing fold growth since at least the late Pleistocene in the Eastern Cordillera, and the early Holocene in the Mera plateau. The preserved terraces of the Pastaza valley are all degradational and are ascribed to periods of tectonic (seismic) activity alternating with periods of tectonic quiescence or decreased seismic activity rather than to climatic events. ¹⁴C dating of the plateau erosion surface and of the upper Pastaza terraces indicates that the minimum average incision rate since 18,000 years BP varies locally in the upper Pastaza valley from 0.5 to 0.67 cm year⁻¹ , increasing from 18,000 years BP to now. A comparison of these incision rates with fold-and-thrust fault uplift rates indicates that incision in the upper Pastaza valley was a result of rapid uplift (up to 1 cm year⁻¹) along the Mirador fold-and-thrust which caused a restoration of the local equilibrium profile of the upper reach, combined with smaller local fault uplift along the westernmost thrust faults. The uplift of the whole Mera plateau with respect to the upper Amazonian basin gives a minimum average uplift rate of 2.8 cm year⁻¹ since 18,000 years BP. The overall uplift of the Mera plateau and the Eastern Cordillera is likely to have been caused by a regional-scale low angle thrust ramp emerging as the frontal thrust fault.     

Influence of natural and anthropogenic factors on the water quality of the coastal waters around the South Andaman in the Bay of Bengal

During the last decade, the Andaman and Nicobar Islands (ANI) have witnessed a marginal population growth with associated variations and degradation in the water quality of the inhabited coastal region. Monthly water quality data collected from six coastal locations in ANI were used to evaluate the anthropogenic influence in an otherwise pristine island environment. Exceptionally low dissolved oxygen (0.7–2.0 mg/L) at the Phoenix Jetty (PJ) and mangrove site indicates hypoxic conditions. Among the nutrients, nitrate shows high values at PJ due to heavy nutrient loading from domestic sewage. The cluster analysis segregated PJ from the remaining sites, indicating deterioration in the water quality. On the other hand, water quality at Sippighat, a low-intensity aquaculture site, does not indicate any deterioration. Apart from the large modulations in the water quality of the study area by the Bay of Bengal waters, the effect of domestic waste discharges significantly affects the coastal waters of Andaman. Though the present water quality at most of the study sites appears acceptable, the increased volume of tourism and allied activities poses a potential threat to the island ecosystem. Besides the anthropogenic influences, the long-term trends in oceanographic factors were analyzed in order to decipher the expected natural effect on future water quality of the region. Based on the increasing sea surface temperature as well as the decreasing chlorophyll-a, eddy kinetic energy, and zonal kinetic energy, we propose that the combined effect of both natural and anthropogenic factors can ultimately distress the present ambient water quality of ANI.     

Effect of simultaneous state–parameter estimation and forcing uncertainties on root-zone soil moisture for dynamic vegetation using EnKF

In this study, an EnKF-based assimilation algorithm was implemented to estimate root-zone soil moisture (RZSM) using the coupled LSP–DSSAT model during a growing season of corn. Experiments using both synthetic and field observations were conducted to understand effects of simultaneous state–parameter estimation, spatial and temporal update frequency, and forcing uncertainties on RZSM estimates. Estimating the state–parameters simultaneously with every 3-day assimilation of volumetric soil moisture (VSM) observations at 5 depths lowered the average standard deviation (ASD) and the root mean square error (RMSE) for RZSM by approximately 1.77% VSM (78%) and 2.18% VSM (93%), respectively, compared to the open-loop ASD where as estimating only states lowered the ASD by approximately 1.26% VSM (56%) and the RMSE by 1.66% VSM (71%). The synthetic case obtained RZSM estimates closer to the observations than the MicroWEX-2 case, particularly after precipitation/irrigation events. The differences in EnKF performance between MicroWEX-2 and synthetic observations may indicate other sources of errors in addition to those in parameters and forcings, such as errors in model biophysics.     

Limno-tolerant bacteria govern nitrate concentration in Mandovi Estuary,India

The spatial and temporal abundances of limno-tolerant and halo-tolerant bacteria were investigated in the tide-dominated Mandovi estuary along the west coast of India. These investigations were carried out in relation to various environmental parameters on a monthly basis at three fixed stations for a year. On an annual basis, the estuary showed an average salinity of 28.2, 17.4, and 12.6 at the mouth, midstream and upstream region. Halo-tolerant retrievable count (HTRC) and limno-tolerant retrievable count (LTRC) of bacteria were in the order of 10⁶ L⁻¹. Among the environmental parameters, a strong negative relationship between salinity and nitrate (r = −0.806; p < 0.001) suggested that 64% of the variation could be due to fresh water influence in the estuary. The limno-tolerant retrievable count (LTRC) brought about 23% variations in nitrate concentration. This influence was maximum during the monsoon (r = 0.522; p < 0.05) especially in the surface waters (r = 0.624; p < 0.001) suggesting nitrate reduction by LTRC. Measurements of nitrate reducing activity (NRA) in whole-water samples along the salinity gradient in the estuary also revealed higher reduction rates at lower salinity upstream. This was further confirmed by culture experiments where the limno-tolerant bacteria showed higher NRA than halo-tolerant forms. It is therefore suggested that LTRC is more actively involved in the variation of nitrate that enters the Mandovi estuary particularly during the monsoon.     

Provenance record of late Maastrichtian–late Palaeocene Andean Mountain building in the Amazonian retroarc foreland basin (Madre de Dios basin,Peru)

Biostratigraphic, sedimentological and provenance analyses suggest that a proto‐Andean Cordillera already existed in southern Peru by late Maastrichtian–late Palaeocene times. A 270‐m‐thick stratigraphic section shows changes in depositional environments from shallow marine (early Maastrichtian) to non‐marine (late Maastrichtian) then back to estuarine (late Palaeocene) conditions. An erosional surface separates lower Maastrichtian from upper Maastrichtian deposits. Above this surface, the late Maastrichtian unit exhibits moderately developed palaeosols and syn‐sedimentary normal faults. The sedimentary evolution is accompanied by a decrease in sedimentation rate and by changes in provenance. Shallow marine lower Maastrichtian deposits have a cratonic provenance as shown by their low εNd(0) values (?15 to ?16) and the presence of Precambrian inherited zircon grains. The upper Maastrichtian deposits have a mixed Andean and cratonic origin with εNd(0) values of ~12.6 and yield the first Cretaceous and Permo‐Triassic zircon grains. Estuarine to shallow marine upper Palaeocene deposits have an Andean dominant source as attested by higher εNd(0) values (?6 to ?10) and by the presence of Palaeozoic and Late Cretaceous zircon grains. The changes in depositional environments and sedimentation rates, as well as the shift in detrital provenance, are consistent with a late Maastrichtian–late Palaeocene period of Andean mountain building. In agreement with recently published studies, our data suggest that an Andean retroarc foreland basin was active by late Maastrichtian–late Palaeocene times.     

Coastal hazard mapping in the Cuddalore region, South India

It is estimated that nearly one-third of India’s population lives on the coast and is dependent on its resources. Shoreline erosion, storm surges and extreme events have resulted in severe loss of human life, damage to ecosystems and to property along the coast of India. Studies carried out in the Cuddalore region of South India reveal that this low-lying coastal zone, which suffered significant erosion during the last century, has been severely affected by the tsunami of 2004, storm floods and cyclones. In response to these impacts, a variety of coastal defense measures and adaptation strategies have been implemented in the region, although with only limited success. In order to inform future coastal planning in this region, the work reported here identifies a composite hazard line, seaward of which coastal flooding events will have a return interval of less than 1 in 100 years. The area landward of the coastal hazard line will be unaffected by 100 years of coastal erosion at present day rates. The study directly supports the Integrated Coastal Zone Management (ICZM) Plan of the Tamil Nadu State through the identification and assessment of coastal hazards and the overall vulnerability to coastal flooding and erosion. The key results from this pilot study will be used directly by the State of Tamil Nadu in the protection of the coastal livelihoods, better conservation measures and sustainable development along the coast. This study is a step toward mapping the hazard line for the entire coast of India that helps protect human lives and property.