Habitat disturbance and marina development: An assessment of ecological effects. I. Changes in primary production due to dredging and marina construction

Potential impacts on primary production were estimated for an 800-slip marina previously planned for Davids Island, located in the extreme western portion of Long Island Sound, New York. Macroalgal and microalgal production in the area of the proposed marina was analyzed on the basis of six depth zones ranging from an existing seawall (at about +2.2 m MLW) seaward to a depth of ?2.4 m MLW. Productivity measurements were based on in situ ¹⁴C uptake studies, chlorophyll a determinations, and varying light exposures within the euphotic zone that were the estimate of daily production calculated for eight dominant macroalgae and microalgae, and summed to estimate existing production in the proposed marina. Similarly, post-construction production was estimated by applying the calculated daily production to the appropriate areas of hard substrate (breakwater, pilings, etc.) in the euphotic zone. Pre- and post-construction macroalgal production values were 50,608 and 42,152 g C d^?1, respectively. This represents a 17% reduction in macroalgal production. It should be noted, however, that production on the seafloor of the marina was not accounted for. Consquently, reductions in macroalgal production that might occur are likely overestimated. Microalgal production constituted less than 3% of total primary production in the nearshore areas of Davids Island. The pre- and post-construction microalgal production values were 1,542 and 743 g C d^?1, respectively. This represents a 48% reduction in microalgal production in unconsolidated sediment. However, micoalgal production would likely occur on hard substrates in the marina. Overall, pre- and post-construction estimates of primary production were remarkably similar, suggesting that production on hard substrates in the marina would compensate for lost production from deepening of the nearshore zone during construction. *** DIRECT SUPPORT *** A01BY074 00012     

Variability of precipitation and temperature in Guanajuato,Mexico

Variability of precipitation and temperature was examined on multiple time scales using data from five surface observing stations in the center of Guanajuato state, Mexico, as well as gridded data from the North American Regional Reanalysis (NARR). Frequency of days with total precipitation exceeding the 90th percentile was not found to have increased from 1979-2011. However, frequency of days with maximum temperature above the 90th percentile more than doubled from 1979-2011, and frequency of days with maximum temperature below the 10th percentile decreased by almost half over the same period, an important result given the scarcity of water resources for the agriculture-based economy. Precipitation within the growing season was found to vary by phase of the Madden-Julian oscillation (MJO), with MJO phases 1-3 associated with above-normal rainfall and MJO phases 4-7 with normal or below normal rainfall. Composite anomalies of precipitation, surface pressure, surface wind, surface temperature, and 700 mbar height showed that days with rainfall in Guanajuato were associated with on-shore, upslope flow, reduced surface temperatures, and reduced potential evaporation. Composites for MJO phases 1-3 and 8 agreed well with these anomalies. Similarly, composite anomalies for days without rainfall in Guanajuato showed warm surface temperatures, broad anticyclonic flow over much of northern Mexico, and enhanced potential evaporation. Composites for MJO phases 4-7 agreed well with these anomalies.     

Link between climate change mitigation and resource efficiency: A UK case study

This paper provides an in-depth analysis of the links between dematerialisation and climate change mitigation. Methods used for material flow analyses (MFA) within the wider context of industrial ecology (which includes a focus on all resource flows in an economy, not purely material tonnage) tend to focus either on detoxification and pollution reduction or dematerialisation and resource productivity. An environmentally extended input–output (EEIO) model incorporates both aspects, which need to be dealt with when looking at how to meet challenging greenhouse gas (GHG) emission targets. The approach understands both production systems and consumption patterns and has the ability through scenarios to analyse the (GHG) effectiveness of a wide range of material efficiency options. This analysis adopts an environmentally extended input–output approach to assess the role of material efficiency measures in reducing UK GHG emissions by 2050. A method for projecting the variables and parameters in the model, including the supply of and demand for materials and products, is presented and applied to investigate thirteen material efficiency strategies in the UK.     

Evidence for cold-based glacial activity in the Allan Hills,Antarctica

Evidence is presented for cold-based glacial erosion, deposition and deformation from the Allan Hills, South Victoria Land, Antarctica. Different erosional features such as scrapes, striae and grooves, depositional features including till, isolated boulders and ice-cored debris cones and three scales of glaciotectonism resulting from cold-based glacial advance are described, and conceptual models are presented based on these observations and those of advancing cold-based glaciers elsewhere. The models entail: (i) ice block apron overriding and entrainment, and (ii) ice-bed separation leading to the formation of a cavity on the down-glacier side of escarpments. The models are most applicable to a horizontally stratified, lithified sedimentary bedrock substrate, but our criteria may assist in correctly interpreting features such as boulder trains, modified bedrock tors and complex cosmogenic exposure histories which have been noted in several regions that may have experienced cold-based glaciation during Pleistocene glacial maxima.     

Potentialities and problems of satellite remote sensing with special reference to arid and semiarid regions

Although satellite remote sensing of the atmosphere and Earth's surface has been pursued now for many years, it has not been applied widely in detailed or systematic investigations of the atmospheric and land surface climates of arid and semiarid regions. This paper briefly surveys characteristics of satellite systems that should be considered when evaluating the present and potential roles of satellite remote sensing in arid and semiarid zone research, and in studies of desertification. Actual and potential applications of satellite data in these research areas are then reviewed. It is concluded that satellite data available for arid and semiarid areas have been used in a very fragmentary and unsystematic manner. Proposals are made for exploiting more fully satellite data, especially in investigations of desertification.     

Axial and transverse deep-water sediment supply to syn-rift fault terraces: Insights from the West Xylokastro Fault Block,Gulf of Corinth,Greece

Deep-water syn-rift systems develop in partially- or transiently-linked depocentres to form complicated depositional architectures, which are characterised by short transport distances, coarse grain sizes and a wide range of sedimentary processes. Exhumed systems that can help to constrain the tectono-stratigraphic evolution of such systems are rare or complicated by inversion tectonics. Here, we document a mid-Pleistocene deep-water syn-rift system fed by Gilbert-type fan deltas in the hangingwall of a rift margin fault bounding the West Xylokastro Horst block, on the southern margin of the Gulf of Corinth, Greece. Structural and stratigraphic mapping combined with digital outcrop models permit observations along this syn-rift depositional system from hinterland source to deep-water sink. The West Xylokastro Fault hangingwall is filled by two distinct sediment systems; an axial system fed by coarse-grained sediment gravity flows derived from fault-tip Gilbert-type fan deltas and a lateral system dominated by mass transport deposits fed from an evolving fault-scarp apron. Abrupt changes in stratigraphic architecture across the axial system are interpreted to record changes in relative base level, sediment supply and tectonics. Locally, depositional topography and intra-basinal structures controlled sediment dispersal patterns, from bed-scale infilling of local rugose topography above mass transport complexes, to basin-scale confinement from the fault scarp apron. These acted to generate a temporally and spatially variable, heterogeneous stratigraphic architecture throughout the basin-fill. The transition of the locus of sedimentation from a rift margin to a fault terrace through the syn-sedimentary growth of a basinward fault produced regressive surfaces updip, which manifest themselves as channels in the deep-water realm and acted to prograde the system. We present a new conceptual model that recognises coeval axial and transverse systems based on the stratigraphic architecture around the West Xylokastro fault block that emphasizes the lateral and vertical heterogeneity of rift basin-fills with multiple entry points.     

The Pb isotopic composition of Jurassic cherts overlying ophiolites in the North Apennines,Italy

In the Mesozoic eugeosynclinal sequences of the Italian North Apennines, ophiolitic rocks are commonly stratigraphically overlain by thick bedded chert sequences of Late Jurassic age. The isotopic composition of Pb contained in upper basalts, lower ferruginous (and in places manganiferous) cherts, middle cherts and upper cherts indicates that simple mixing occurred in the sediments between basalt-derived Pb, and more radiogenic Pb provided by fine-grained terrigenous detritus, radiolarian silica and possibly seawater.The most ferruginous cherts are those nearest the ophiolitic basement, which is interpreted as ocean crust formed early in the opening of the Apennine ocean. Hematite content, considered to represent original Fe hydroxy-oxide chemical precipitate in the sediment, decreases upwards in a general way to very low values in the upper cherts. The most ferruginous cherts also contain the highest volcanogenic Pb component and total Pb, whereas higher cherts contain mainly terrestrially-derived Pb. These relations indicate a volcanic-hydrothermal origin for a significant portion of the Pb in the basal to middle parts of the chert formation, and suggest a similar origin for the hematitic Fe. The vertical distribution of hematite and volcanogenic Pb suggests that some initial Fe precipitates, carrying such Pb, had a widespread lateral dispersal after formation at an active ridge.