Effects of temperature on cellular and biochemical parameters in the crab Carcinus aestuarii (Crustacea, Decapoda)

The effects of temperature on cellular and biochemical parameters of the crab Carcinus aestuarii were evaluated. Crabs were kept for 7 days at 4, 17 (reference value) and 30 °C (salinity of 35 psu), and total haemocyte count (THC), haemocyte volume, haemocyte proliferation, phenoloxidase (PO) activity in both haemocyte lysate (HL) and cell-free haemolymph (CFH), CFH total protein and glucose levels, superoxide dismutase (SOD) and catalase (CAT) activities in both gills and digestive gland were evaluated. The lowest and the highest temperature significantly decreased THC, whereas haemocyte volume and haemolymph glucose concentration did not differ significantly among experimental conditions. Haemolymph protein concentration significantly reduced in crabs maintained at 30 °C, when compared with that of animals kept at 4 and 17 °C. Haemocyte proliferation increased significantly in crabs kept at 4 and 30 °C, when compared with that of crabs held at 17 °C. Likewise, a significantly higher PO activity was recorded in CFH from crabs kept at 4 and 30 °C, than in control crabs. Conversely, PO activity did not vary significantly in HL. With regard to antioxidant enzyme activities, a significant decrease in CAT activity was observed in gills from crabs kept at 4 °C, when compared to that of crabs kept at 17 °C and 30 °C. Results obtained demonstrated that the highest and lowest temperature tested influenced crab biological responses, and indicated that C. aestuarii modulated its cellular and biochemical parameters (mainly haemocyte proliferation, CFH protein concentrations and CFH PO activity) in order to cope with temperature.     

Riders under storms: Contributions of nomadic herders’ observations to analysing climate change in Mongolia

Predictions of climate change and its impacts are highly uncertain at regional and local levels. Downscaled models often operate with a too coarse scale and look at standard parameters that may be irrelevant to resource-dependent people. This article argues that a more robust analysis and prediction of climate change at local levels can be inferred from the integration of local people's observation of change with meteorological records and models.The example proposed here is the analysis of climate change in the desert-steppe region of Mongolia. While regional models and local analyses agree that Mongolia has become warmer, predictions either ignore or are contradictory about the changes in precipitations and sand storms. The Mongolian pastoral nomads on the other hand identify longer and more intense droughts and sand storms as the most important recent climatic changes, relevant to their livelihoods. In addition, they record detailed changes in the precipitations regime. Thus, they are unequivocal that rains have become patchy – ‘silk embroidery rains’ – (forcing pastoralists to move farther and more frequently), more intense (thus less effective due to runoff) and that summer rains are delayed (reducing the growing season).The observations of the pastoralists can only partly be investigated in light of meteorological records due to different parameters observed by the two systems. Nevertheless, additional evidence derived from the analysis of meteorological records resonates with the perceptions of the herders and adds elements for further investigation. This combined evidence suggests that due to a southern shift of the East Asian Monsoon, rains in southern Mongolia rely on re-circulated local moisture, leading to large-scale droughts and in turn more frequent sand storms.The analysis provided herein shows that combining the two knowledge systems (local people's observations and climatology) holds the potential to provide more reliant and relevant investigations of climate change and allow for better planned adaptations.     

Offshore Atlas Project: Methodology and Results

The Offshore Atlas Project (OAP) grouped 4,325 Miocene and older and 5,622 Pliocene and Pleistocene productive sands in the Gulf of Mexico into 91 chronostratigraphic hydrocarbon plays to aid the oil and gas industry with regional hydrocarbon exploration and field development. OAP has produced a two-volume atlas series entitled Atlas of Northern Gulf of Mexico Gas and Oil Reservoirs. Volume 1 comprises Miocene and older reservoirs, while volume 2 comprises Pliocene and Pleistocene reservoirs. Chronozones (Reed et al., 1987) were used to define geologic ages in the Gulf of Mexico. A chronozone is a time-stratigraphic unit defined by a particular benthic foraminifera biostratigraphic zone. The 26 chronozones identified by Reed et al. (1987) were further grouped into 14 Cenozoic and 2 Mesozoic chronozones for OAP. A composite type log (CTL), which shows the chronostratigraphic relationship of all productive sands in a field, was constructed for each of the 876 proved federal fields in the Gulf of Mexico. Depositional facies (retrogradational, aggradational, progradational, and submarine fan)were next identified on each CTL. The four facies were identified primarily according to characteristic SP-curve shapes, paleoecozones, and sand content. The chronozones and depositional facies identified on each CTL were then correlated among fields across the Gulf of Mexico. All productive sands correlated to the same chronozone and depositional facies were then identified as a unique play. Both federal and state fields in the Gulf of Mexico contain original proved reserves (sum of cumulative production and remaining proved reserves) estimated at 12.481 Bbbl of oil and condensate and 156.466 Tcf of gas (40.322 Bboe [sum of liquids and energy equivalent gas]). Of this, 9.943 Bbbl of oil and condensate and 122.263 Tcf of gas (31.698 Bboe) have been produced. Miocene plays contain the most total original proved reserves with 41.9 %, followed by Pleistocene plays (36.2 %), Pliocene plays (18.6 %), Mesozoic plays (2.9 %), and Oligocene plays (0.4 %). Miocene plays have produced the largest amount of total hydrocarbons, as well, at 43.5 % followed by Pleistocene plays (36.5 %), Pliocene plays (19.1 %), Oligocene plays (0.5 %), and Mesozoic plays (0.4 %). Just over two-thirds of the Gulf of Mexico's total original proved reserves are contained in progradational facies (67.4 %),with the remainder comprising submarine-fan facies (18.5 %), aggradational facies (9.9 %), retrogradationalfacies (2.4 %), combination facies (1.7 %), and caprock and reef reservoirs (0.1 %). Total cumulative production from the different facies closely mimics the distribution of original proved reserves. Of the 91 plays, the lower Pleistocene progradational play (LPL P.1) contains the most original proved gas reserves (10.5 %) and has produced the most gas (11.4 %). However, the upper upper Miocene eastern progradational play (UM3 P.1B) contains the most original proved oil and condensate reserves (18.9 %) and has produced the most oil and condensate (21.4%). Several technical studies resulting from OAP have been published. Hunt and Burgess (1995) described the distribution of OAP plays deposited by the ancestral Mississippi River delta system in the north-central Gulf of Mexico over the past 24 million years. The lower Miocene plays are restricted to the westernmost portion of the Louisiana shelf. In the late middle Miocene, the depocenter migrated east of the present-day Mississippi River delta. During the late upper Miocene, the depocenter began migrating back to the west and prograded basinward, and it continued to do so throughout the Pliocene and Pleistocene. Lore and Batchelder (1995) discussed how OAP plays can be used to find exploration targets and assess undiscovered resources. As an exploration tool, OAP play maps can be used to identify conceptual submarine-fan plays downdip of established shallow water producing facies, and to identify wells where a known producing facies or chronozone has not yet been reached. As an assessment tool, the extensive data sets associated with each OAP play can be used to infer statistically the size of undiscovered resources in a play to determine if exploration in that play is economically justifiable. Lore et al. (1995) estimated the amount of undiscovered conventionally recoverable resources in the Gulf of Mexico, basing their assessment on previous work performed for OAP. Mean level estimates show that, by far, submarine-fan plays have the greatest potential for additional oil and gas in the Gulf of Mexico, with 75.1 % and 70.4 % of the total oil and gas resources, respectively. Mean level estimates for the 13 OAP Miocene, Pliocene, and Pleistocene chronozones show that upper Pleistocene plays have the most oil resource potential (24.3 %), while lower Pleistocene plays have the most gas resource potential (20.6 %).     

The age of Spitsbergen basement consolidation: U–Pb dating of detrital zircons from the Upper Precambrian and Lower Carboniferous clastic rocks of the northwestern part of Nordenskiöld Land

The age distribution of detrital zircons from Upper Riphean and Early Carboniferous sandstones of the northwest part of Nordenskiöld Land (Spitsbergen Island) was studied. The results obtained supplement the previously known data on the rocks of Precambrian and Paleozoic masses of West Spitsbergen. Integrated consideration of these data showed that the time interval from the Middle Riphean to the Early Carboniferous inclusive might be subdivided into at least five stages characterized by quite different provinces supplying detritus to sedimentary basins. (The relics of these latter are represented in the present structure of western Svalbard.) The most ancient distinguished event of alteration of the sources of sedimentary matter (at the boundary of the Middle and Late Riphean) corresponds to the consolidation time of the ancient basement of Svalbard.     

The East Caledonian Current: A Case Example for the Intercomparison between AltiKa and In Situ Measurements in a Boundary Current

This paper presents an assessment of SARAL/AltiKa satellite altimeter for the monitoring of a tropical western boundary current in the south-western Pacific Ocean: the East Caledonian Current. We compare surface geostrophic current estimates obtained from two versions of AltiKa along-track sea level height (AVISO 1 Hz and PEACHI 40 Hz) with two kinds of dedicated in situ datasets harvested along the satellite ground tracks: one deep-ocean current-meter mooring deployed in the core of the boundary current and five glider transects. It is concluded that the AltiKa-derived current successfully captures the velocity of the boundary current, with a standard error of 11 cm/s with respect to the in situ data. It also appears important to reference AltiKa sea level anomaly to the latest mean dynamic topography available in our area. Doing so, Ka-band altimetry provides a satisfactory representation of the western boundary current. Thereby, it usefully contributes to observing its variability in such a remote and under-observed ocean region. However, the rather long repeat period of SARAL (35 days) in comparison to the high frequency variability seen in the flow velocity of the boundary current calls for a combined use of SARAL with the other satellite altimetry missions.