On the ecology of oligochaetes: Monthly variation of community composition and environmental characteristics in two South Carolina tidal creeks

In the tidal creeks of the southeastern United States, the numerically and ecologically dominant macrobenthic organisms are typically oligochaetes. Due to their relatively small size and difficult taxonomy, little is known about the short-term and seasonal changes in the oligochaetes of tidal creeks. This study presents a report of the spatial and temporal changes of the oligochaete taxa within and between two tidal creeks in southern South Carolina, at monthly intervals over a 13-month period. These changes are framed within the reference of monthly changes in benthic chlorophylla, sediment composition, and porewater ammonia, as well as in the perspective of seasonal changes in the entire tidal creek macrobenthic community. The most abundant oligochaete found in this study was the tubificidMonopylephorus rubroniveus, followed by the naidParanais litoralis and the tubificidsTubificoides heterochaetus andT. brownae. All of the oligochaetes exhibited strong month-to-month and spatial changes, indicative of changes in water quality and sediment habitat characteristics (e.g., low dissolved oxygen, high benthic chlorophylla). There were significant correlations between the abundance of most species and either benthic chlorophylla concentration or the silt-clay fraction of the sediment. Looking at short-term changes in this rapidly changing component of the macrobenthic community provides insight not only into the ecology of the oligochaetes, but also into the changes in the tidal creek ecosystem and their potential effects on other biota.     

Climate, water management, and policy in the San Pedro Basin: results of a survey of Mexican stakeholders near the U.S.–Mexico border

This paper reviews regional climate knowledge and vulnerability in the northern Mexico San Pedro River Basin, with a focus on water quality, quantity, and management issues on the Mexican side of the border. A discussion based on the available literature is supplemented by a survey assessing concerns about water and the quality and usability of climate and hydrologic information available to water managers and communities. The surveys indicate that the central concern for urban residents is the lack of reliable potable water due to frequent service breakdowns–with climate change and variability, specifically drought and high temperatures, as contributing factors. Water managers desire appropriate meteorological and hydrologic information to improve planning strategies, but access to this information remains limited. Considerable disagreement exists about who should pay for previously free or low-cost water and wastewater treatment. Urban users have little incentive to conserve because of the present flat, low rate and frustration with service. In rural areas, while a majority of ranchers recognize that variable climate and water loss could increasingly jeopardize their lifestyle, they seldom use meteorological information in planning or modify their water consumption. Climate vulnerability also includes potential for serious environmental health issues due to the presence of heavy metals and organic contaminants in the San Pedro.     

Relationships Between Meteorological and Water Quality Variables and Fisheries-Independent White Shrimp (<Emphasis Type="Italic">Litopenaeus setiferus</Emphasis>) Catch in the ACE Basin NERR,South Carolina

White shrimp (Litopenaeus setiferus) fisheries-independent and fisheries-dependent landings can be highly variable and may be related to environmental factors that influence growth, mortality, and survival. We used linear regression analysis to look for potential relationships between environmental and white shrimp catch-per-unit-effort (CPUE) data collected from the Ashepoo-Combahee-Edisto (ACE) Basin National Estuarine Research Reserve (NERR) for four critical months in the shrimp life cycle. This analysis used data from white shrimp fisheries-independent CPUE (2002 to 2014) and water quality and meteorological variables for August (juvenile), December (sub-adult), March (adult), and April (spawning adult). The results showed that shrimp CPUE was mainly correlated with water temperature, salinity, and dissolved oxygen concentration collected through the ACE Basin NERR’s System-Wide Monitoring Program (SWMP), but offshore wind, precipitation, and intra-annual CPUEs also partially explained the variability in monthly CPUEs. Black gill prevalence was correlated with water temperature and salinity. Additionally, our analysis found that winter water temperatures of ≤11 °C were correlated with reduced shrimp abundance the following spring. Ultimately, managers would like to successfully predict white shrimp stock abundance throughout fishing seasons based on environmental conditions. This study is a first step in identifying the environmental variables that may be useful in predicting white shrimp CPUE in the South Atlantic Bight. The techniques employed here can serve as a basis for predicting and managing other wild annual fisheries stocks.     

The Morcles microgranite (Aiguilles Rouges,Swiss Alps): geochronological and geochemical evidences for a common origin with the Vallorcine intrusion

The Morcles microgranite is located in the N–E termination of the Aiguilles Rouges massif (External Crystalline Massifs, Switzerland). It outcrops as dykes, a few meters to 150 m in thickness, intruding the Aiguilles Rouges polymetamorphic basement, and presents variation of texture from granophyric to rhyolitic. We present here for the first time, in situ U–Pb zircon dating of the Morcles microgranite/rhyolite based on laser-ablation—inductively coupled plasma—mass spectrometry (LA-ICP-MS) data. Results indicate late Variscan emplacement ages at ~303 and ~309–312 Ma, a major Caledonian inherited component age at ~445–460 Ma, and secondary inherited ages ranging from Pan-African (550–1000 Ma) to Paleoproterozoic (2.3 Ga). Geochronological and geochemical data indicate that the Morcles microgranite/rhyolite shares a common origin with the higher (or “H”) facies of the neighbouring Vallorcine granitic intrusion. This close affinity is further corroborated by the geographical alignment of both intrusive bodies on either side of the Rhone Valley. The fine-grained texture of the microgranite groundmass and the rhyolite indicates a very rapid cooling rate and emplacement close to the surface, suggesting that the Morcles microgranite/rhyolite may constitute the shallow-level counterpart of the Vallorcine granite. The mineralogical assemblages observed in the Morcles microgranite/rhyolite support the idea of high-temperature melting conditions provided by underplating of mantle-derived magmas during the Carboniferous extension of the Variscan cordillera.     

Comparison of C and N stable isotope ratios between surface particulate organic matter and microphytoplankton in the Gulf of Lions (NW Mediterranean)

Carbon and nitrogen stable isotope ratios of particulate organic matter (POM) in surface water and 63–200 μm-sized microphytoplankton collected at the fluorescence maximum were studied in four sites in the Gulf of Lions (NW Mediterranean), a marine area influenced by the Rhone River inputs, in May and November 2004. Some environmental (temperature, salinity) and biological (POM, Chlorophyll a and phaeopigments contents, phytoplankton biomass and composition) parameters were also analysed. Significantly different C and N isotopic signatures between surface water POM and microphytoplankton were recorded in all sites and seasons. Surface water POM presented systematically lower δ¹³C (∼4.2‰) and higher δ¹⁵N (∼2.8‰) values than those of microphytoplankton, due to a higher content of continental and detrital material. Seasonal variations were observed for all environmental and biological parameters, except salinity. Water temperature was lower in May than in November, the fluorescence maximum was located deeper and the Chlorophyll a content and the phytoplankton biomass were higher, along with low PON/Chl a ratio, corresponding to spring bloom conditions. At all sites and seasons, diatoms dominated the phytoplankton community in abundance, whereas dinoflagellate importance increased in autumn particularly in coastal sites. C and N isotopic signatures of phytoplankton did not vary with season. However, the δ¹⁵N of surface water POM was significantly higher in November than in May in all sites likely in relation to an increase in ¹⁵N/¹⁴N ratio of the Rhone River POM which influenced surface water in the Gulf of Lions. As it is important to determine true baseline values of primary producers for analysing marine food webs, this study demonstrated that C and N isotopic values of surface water POM cannot be used as phytoplankton proxy in coastal areas submitted to high river inputs.     

Young asteroid mixing revealed in ordinary chondrites: The case of NWA 5764, a polymict LL breccia with L clasts

Polymict chondritic breccias—rocks composed of fragments originating from different chondritic parent bodies—are of particular interest because they give insights into the mixing of asteroids in the main asteroid belt (occurrence, encounter velocity, transfer time). We describe Northwest Africa (NWA) 5764, a brecciated LL6 chondrite that contains a >16 cm³ L4 clast. The L clast was incorporated in the breccia through a nondestructive, low‐velocity impact. Identical cosmic‐ray exposure ages of the L clast and the LL host (36.6 ± 5.8 Myr), suggest a short transfer time of the L meteoroid to the LL parent body of 0.1 ± 8.1 Myr, if that meteoroid was no larger than a few meters. NWA 5764 (together with St. Mesmin, Dimmitt, and Glanerbrug) shows that effective mixing is possible between ordinary chondrite parent bodies. In NWA 5764 this mixing occurred after the peak of thermal metamorphism on the LL parent body, i.e., at least several tens of Myr after the formation of the solar system. The U,Th‐He ages of the L clast and LL host, identical at about 2.9 Ga, might date the final assembly of the breccia, indicating relatively young mixing in the main asteroid belt as previously evidenced in St. Mesmin.     

广东徐闻县西部沿岸海域的珊瑚虫纲物种

广东省徐闻县西部沿岸海域分布着珊瑚礁,现生珊瑚虫纲物种较丰富,本文将2004年调查研究的结果,结合文献记录的资料,综合整理,统计有石珊瑚目12科29属56种和5未定种,其它珊瑚虫纲物种有6目15科31种和12未定种．如进一步深入调查研究,还会有本区新的记录．本区石珊瑚目比处于更低纬度的海南岛种属少,但比处于更高纬度的涠洲岛种属多,符合喜热的物种依自然带分布的规律．     

A study of fecal coliform sources at a coastal site using colored dissolved organic matter (CDOM) as a water source tracer

Optical properties of colored dissolved organic matter (CDOM) were measured as a tracer of polluted waters in a Southern California surf-zone with consistently high levels of fecal indicator bacteria. Salinity, temperature, fecal coliform, absorbance (200-700nm) and fluorescence (lambda(excitation)=350nm; lambda(emission)=360-650nm) were measured in the creek and surf-zone during a dry and rain event. Fluorescence to absorption ratios for CDOM were used to distinguish water masses, with two distinct CDOM end-members identified as creek (flu/abs=8.7+/-0.8x10(4)) and coastal (flu/abs=2.2+/-0.3x10(4)). Waters containing the same CDOM end-member had highly variable bacterial levels during the dry event, suggesting intermittent sources of bacteria added to a uniform water source, consistent with marine birds. During the rain event, increased levels of the creek end-member and bacteria indicated a second bacteria source from runoff.     

Geologic assessment and injection design for a pilot CO<Subscript>2</Subscript>-enhanced oil recovery and sequestration demonstration in a heterogeneous oil reservoir: Citronelle Field,Alabama, USA

CO₂ pilot injection studies, with site-specific geologic assessment and engineering reservoir design, can be instrumental for demonstrating both incremental enhanced oil recovery and permanent geologic storage of greenhouse gases. The purpose of this paper is to present the geologic and reservoir analyses in support of a field pilot test that will evaluate the technical and economic feasibility of commercial-scale CO₂-enhanced oil recovery to increase oil recovery and extend the productive life of the Citronelle Oil Field, the largest conventional oil field in Alabama (SE USA). Screening of reservoir depth, oil gravity, reservoir pressure, reservoir temperature, and oil composition indicates that the Cretaceous-age Donovan sand, which has produced more than 169 × 10⁶ bbl in Citronelle Oil Field, is amenable to miscible CO₂ flooding. The project team has selected an 81 ha (200 ac) 5-spot test site with one central gas injector, two producers, and two initially temporarily abandoned production wells that are now in production. Injection is planned in two separate phases, each consisting of 6,804 t (7,500 short tons) of food-grade CO₂. The Citronelle Unit B-19-10 #2 well (Permit No. 3232) is the CO₂ injector for the first injection test. The 14-1 and 16-2 sands of the upper Donovan are the target zones. These sandstone units consist of fine to medium-grained sandstone that is enveloped by variegated mudstone. Both of these sandstone units were selected based on the distribution of perforated zones in the test pattern, production history, and the ability to correlate individual sandstone units in geophysical well logs. The pilot injections will evaluate the applicability of tertiary oil recovery to Citronelle Field and will provide a large volume of information on the pressure response of the reservoirs, the mobility of fluids, time to breakthrough, and CO₂ sweep efficiency. The results of the pilot injections will aid in the formulation of commercial-scale reservoir management strategies that can be applied to Citronelle Field and other geologically heterogeneous oil fields and the design of similar pilot injection projects.     

Mangrove forest sedimentation and its reference to sea level rise,Cananeia, Brazil

The stability of a mangrove ecosystem in Cananeia, Brazil, is assessed based on investigations of the site-specific temporal rise in relative sea level during the past 50 years, 100-year sediment accumulation rates (SAR) and sources of organic matter (OM). Addressing this, three sediment cores were collected in a transect, intertidal mud flat, mangrove margin and well into the forest. The net SAR, as estimated by the age–depth relationships of ²¹⁰Pb and ¹³⁷Cs, is between 2.5 and 3.9 mm year⁻¹. These rates are comparable to the estimates based on the Pb and Zn contaminant markers corresponding to mining initiation in the region in 1918. Further, the SARs are lower than the rate of regional relative sea level rise (4 mm year⁻¹) as indicated by the past 50-year tide gauge record, but the rate is higher than the eustatic sea level rise (1.7 ± 0.3 mm year⁻¹). The stratigraphies of TOC/TN, δ¹³C_(OC), OP and δ¹⁵N indicate site-specific mangal vegetal litter, which is the predominant source of OM at all core sites, during the past century and reflects a stable mangal system over that time span.