The rocky, photic benthos of Arctic and Subarctic Biogeographic Regions has a characteristic seaweed flora that includes an extensive high-magnesium calcium carbonate basal layer of crustose coralline red algae. The thickest (10-40 cm) and oldest parts of the crust (previously reported as up to 640-830 years old), primarily at mid-photic depths of 15-25 m, are composed of buildups of the genus Clathromorphum. Due to its annual growth increments and cycling of Mg content with temperature, Clathromorphum has recently been developed as a high-resolution climate archive. The age of the archive is primarily limited by the boring of mollusks that reduce structural integrity, remove the record, and induce local diagenesis. Depressions and gentle slopes in the deeper portions of Subarctic rocky bottoms often collect mixed bioclastic and siliciclastic sediments, including a dense cover of rhodoliths (Lithothamnion glaciale and Lithothamnion tophiforme). In this paper we describe a transition zone of these two environments that forms on cobble/boulder glacial erratic bottoms in northern Labrador. Clathromorphum compactum buildups on the boulders and cobbles projecting through rhodolith beds can be preserved by finegrained anaerobic sediments that in turn reduce mollusk boring. This significantly enhances preservation and longevity of C. compactum crusts. We describe specimens of ages up to 1200 years BP, and discuss how greater ages can be obtained for archiving high-resolution climate information.

We paired a 361 d laboratory mesocosm experiment and a 383 d field experiment with rhodoliths (Lithothamnion glaciale) collected in Newfoundland (Canada) to test the overall hypothesis that growth in subarctic rhodoliths is chiefly controlled by irradiance. Rhodoliths in the laboratory were exposed to 1 of 5 seawater temperatures (ambient, 2, 4, 7, and 10°C) and 1 of 3 irradiances (low [0.02], intermediate [0.11], and high [0.27 mol photons m-2 d-1]). Rhodoliths in the field were held in cages at 3 depths (8, 15, and 25 m). Laboratory results demonstrated that growth is unaffected by temperatures between ~1 and 16°C. Field results suggested that growth ceases at temperatures near or below 0.5°C and showed that the annual growth profile of L. glaciale comprises 3 distinct phases, namely 2 of positive growth separated by 1 of arrested growth, and that the switch from one phase to the next coincides with seasonal shifts in sea temperature and light regimes. Rhodoliths at 25 m appeared to utilize light nearly twice as efficiently as rhodoliths at 15 m, which enabled similar growth at both depths despite the ~60% lower irradiance at 25 m. We conclude that growth is chiefly controlled by irradiance and that temperature effects may override, but not interact with, those of irradiance during the coldest months of the year. Subarctic L. glaciale rhodoliths are resilient to changes in sea temperature over a relatively broad thermal range, with sustained growth even at temperatures above those normally observed during most of the year in Newfoundland coastal waters and northwards.

Abstract. The shallow-marine benthic coralline alga Clathromorphum compactum is an important annual- to sub-annual-resolution archive of Arctic and subarctic environmental conditions, allowing reconstructions going back > 600 years. Both Mg content, in the high-Mg calcitic cell walls, and annual algal growth increments have been used as a proxy for past temperatures and sea ice conditions. The process of calcification in coralline algae has been debated widely, with no definitive conclusion about the role of light and photosynthesis in growth and calcification. Light received by algal specimens can vary with latitude, water depth, sea ice conditions, water turbidity, and shading. Furthermore, field calibration studies of Clathromorphum sp. have yielded geographically disparate correlations between MgCO3 and sea surface temperature. The influence of other environmental controls, such as light, on Mg uptake and calcification has received little attention. We present results from an 11-month mesocosm experiment in which 123 wild-collected C. compactum specimens were grown in conditions simulating their natural habitat. Specimens grown for periods of 1 and 2 months in complete darkness show that the typical complex of anatomy and cell wall calcification develops in new tissue without the presence of light, demonstrating that calcification is metabolically driven and not a side effect of photosynthesis. Also, we show that both light and temperature significantly affect MgCO3 in C. compactum cell walls. For specimens grown at low temperature (2 ∘C), the effects of light are smaller, with a 1.4 mol % MgCO3 increase from low-light (mean = 17 lx) to high-light conditions (mean = 450 lx). At higher (10 ∘C) temperature there was a 1.8 mol % MgCO3 increase from low to high light. It is therefore concluded that site- and possibly specimen-specific temperature calibrations must be applied, to account for effects of light when generating Clathromorphum-derived temperature calibrations.

Summary Permanent downhole monitoring can provide valuable information for production decisions in real time without the need to perform an intervention to collect data. One of the commercial permanent monitoring technologies is the fiber-optic DTS, which can record the wellbore temperature profile in real time with decent accuracy and resolution. A key potential application for DTS data is to profile injection or production for wells, which is the primary motivation and focus of this project. In the present paper, a thermal model recently developed for single-phase- and multiphase-fluid flow along a vertical, deviated, or horizontal well will first be briefly described. The model can be applied for both wellbore temperature prediction (forward modeling) and for flow profiling using a measured temperature profile (inverse problem). The model has successfully been applied for investigating key thermal characteristics of single-phase- and multiphase-fluid flow along a wellbore. In particular, the dependence of wellbore temperature upon phases, flow profile, fluid type, fluid properties, well deviation, and Joule-Thomson effect will be demonstrated in the paper. The model has further been adapted for directly predicting production and injection profiles (i.e., flow profiling) based on a given wellbore temperature profile. The potential impact of noise in the DTS measurement on flow profiling has been explored. It is found that the wellbore temperature does not change significantly along horizontal or near-horizontal sections because of the small variation in geothermal temperature. Therefore, based only on steady-state DTS data, the amount and the location of each fluid entry would be difficult to identify. The current study shows that a maximum wellbore deviation of 75° should be honored to appropriately estimate flow profile directly through steady-state DTS data. The study has also led to an observation that under certain circumstances such as multiphase flow, a production profile may be determined through DTS temperature measurement with extra data or information provided. The types of the extra measurements and the appropriate approaches will be recommended. Introduction The DTS system has become a compelling piece of equipment to be considered for permanent downhole monitoring design. DTS provides real-time temperature profile measurement, which can enhance understanding of the flow downhole. DTS systems have been installed all over the world (Johnson et al. 2004; Brown et al. 2005; Tolan et al. 2001; Brown et al. 2004; Brown et al. 2000; Kragas et al. 2001; Lanier et al. 2003; Fryer et al. 2005; Kluth et al. 2000; McKay et al. 2000)—including the North Sea, the Gulf of Mexico, Asia Pacific, Mexico, Venezuela, Texas, and California, to name a few—for steam breakthrough detection, water and gas injection management, production profiling, behind-pipe flow diagnostics, and reservoir surveillance. Flow profiling by temperature log can be traced back to the 1960s and 1970s, when a couple of techniques (Ramey 1962; Curtis and Witterholt 1973; Romero-Juárez 1969) were proposed to quantitatively estimate flow rates at various wellbore positions. The techniques are based on analytical solutions [e.g., the Ramey solution (Ramey 1962)] and have not gained much success because of certain limitations associated with temperature acquisition, data resolution, and the techniques themselves. More details can be found in SPE Monograph No. 14 (Hill 1998). Similar thinking has been extended to single-phase and multiphase flow along more complex wellbore configurations. Models, procedures, and applications have been developed for wellbore temperature profile prediction and flow profiling through temperature logs. Partial details will be documented in the present paper. The focus will be on the impact of fluid phase on wellbore temperature profiles as well as exploring the scenarios where it is feasible to predict flow profiles with temperature logs. Addressing these issues would help petroleum engineers set realistic expectations for a DTS system that can easily take up a significant portion of well Capex expenditures.

for their cataloging and scholarship on the Foslie collection and for their mentorship of the next generation of corallinologists.