Biologically induced alternative states in two rocky subtidal benthic communities

This thesis is concerned with the contrasting communities that occur in the subtidal zones of two closely situated islands in Saldanha Bay on the west coast of South Africa: Both are guano islands, supporting substantial populations of seabirds. They have a similar bottom topography and experience similar physical conditions. Despite these similarities their subtidal benthic communities are however, radically different. Marcus Island has prolific beds of the black mussel Choromytilus meridionalis, accompanied by a large number of other species, notably the sea urchin Parechinus angulosus, the holothurians Pentacta doliolum, Thyone aurea and Trachythyone insolens, large population of whelks, mostly Burnupena spp. and the barnacles Austromegabalanus cylindricus and Notomegabalanus algicola. In contrast, Malgas Island is dominated by a large population of the rock lobster Jasus lalandii together with a dense seaweed flora, and has small numbers of the ribbed mussel Aulacomya ater and the whelks Argobuccinum pustulosum and Burnupena papyracea

FP6 CEDER Project Deliverable 3.2 "Benefits of a new reporting system"

Addressing the uncertainties in fishing activities, the CEDER project examines the use of observer reports, landings, e-logbooks, VMS and GPS tracks, and fishery-specific information. Such information was assessed in order to provide more accurate and timelier data on effort, catches, discards, and/or landings. This document contains CEDER¿s Project Implementation Plan for policy makers, as well as expected benefits for government, industry, and science. The CEDER consortium advocates the use of GPS data at 15 minute intervals for scientific purposes. Among these are improved spatial planning and a new fishing effort measure, the actual effort while fishing, which can be inferred from vessel behaviour. The correlation between catch and effort can be used as an indicator for inspectors, but one cannot reliably guess catches from effort. VMS and logbook data can be matched using rule-bases systems, leading to higher data quality and better use of quota. Furthermore, if fishing mortality were known in near real time, then the integration of current year fishing mortality into management plans would yield benefits for stock recovery. The full realisation of such benefits requires a re-appraisal of the 15% TAC revision rule. The CEDER consortium insists that any roll-out of the ERS e-logbook must be properly enforced, and that the e-logbook cannot by itself replace observer reports. Finally, estimating discards may be feasible in selected fisheries, but additional means such as gear sensors may be required in order to get more reliable data in the general case.JRC.G.4-Maritime affair

FP6 CEDER Project Deliverable 1.1.2 "Data Quality Report"

Addressing the uncertainties in fishing activities, the CEDER project harnessed fishery observer reports, landings, logbooks, and VMS records information. The project collected data from these sources for six selected fisheries. This document explores the quality of aforementioned data.JRC.G.4-Maritime affair

Evidence for habitual use of fire at the end of the Lower Paleolithic: Site-formation processes at Qesem Cave, Israel

The Amudian (late Lower Paleolithic) site of Qesem Cave in Israel represents one of the earliest examples of habitual use of fire by middle Pleistocene hominids. The Paleolithic layers in this cave were studied using a suite of mineralogical and chemical techniques and a contextual sedimentological analysis (i.e., micromorphology). We show that the lower ca. 3 m of the stratigraphic sequence are dominated by clastic sediments deposited within a closed karstic environment. The deposits were formed by small-scale, concentrated mud slurries (infiltrated terra rosa soil) and debris flows. A few intervening lenses of mostly in situ burnt remains were also identified. The main part of the upper ca. 4.5 m consists of anthropogenic sediment with only moderate amounts of clastic geogenic inputs. The deposits are strongly cemented with calcite that precipitated from dripping water. The anthropogenic component is characterized by completely combusted, mostly reworked wood ash with only rare remnants of charred material. Micromorphological and isotopic evidence indicates recrystallization of the wood ash. Large quantities of burnt bone, defined by a combination of microscopic and macroscopic criteria, and moderately heated soil lumps are closely associated with the wood-ash remains. The frequent presence of microscopic calcified rootlets indicates that the upper sequence formed in the vicinity of the former cave entrance. Burnt remains in the sediments are associated with systematic blade production and faunas that are dominated by the remains of fallow deer. Use-wear damage on blades and blade tools in conjunction with numerous cut marks on bones indicate an emphasis on butchering and prey-defleshing activities in the vicinity of fireplaces

RTI (“Real-Time Incentives”) outperforms traditional management in a simulated mixed fishery and cases incorporating protection of vulnerable species and areas

The recently proposed 'Real-Time Incentive (RTI)' fisheries-management approach replaces catch or landings quotas and days-at-sea limitations with a single allowance of fishing-impact credits ('RTIs'). According to this concept, fishing mortality rates of multiple species and impacts on the ecosystem are regulated through a single 'currency'. Fishers can fish where and when they want and spend their allocated RTIs according to spatiotemporally varying tariffs. Managers set the tariffs based on agreed target mortality rates of multiple species, using knowledge of the spatiotemporally varying catchabilities of the various species caught or impacted in a mixed fishery. We explore algorithms for combining real-time CPUE data of up to four different species in a conceptual simulation model. The simulations indicate that RTI may perform better than several traditional management systems, such as broad-brush effort restrictions, Total Allowable Catches and Total Allowable Landings, in terms of controlling harvest rates of several species in a mixed fishery with differing catchabilities, while at the same time limiting impact on a vulnerable species or ecosystem elements. Performance weakens with greater spatial overlap of the 'choke' and other species, and also when fish migrate. Real-time updating requires that local CPUE levels in a given time step are predictive of catchabilities in the following time step. Historical information may be more accurate than real-time information if migration patterns are similar year-on-year. RTI allows the fishers to derive the balance between limiting mortality on choke and vulnerable species and optimally exploiting others because it internalises the cost of undesirable outcomes. In the light of the Ecosystem Based Approach to Fisheries Management, and in particular in the context of the European Union landings obligation, the integrated RTI fisheries management approach could offer a practical solution that addresses some of the problems inherent in a multi-objective fishery system. RTI is ready for case-specific testing

Imprecision of Adaptation in Escherichia coli Chemotaxis

Adaptability is an essential property of many sensory systems, enabling maintenance of a sensitive response over a range of background stimulus levels. In bacterial chemotaxis, adaptation to the preset level of pathway activity is achieved through an integral feedback mechanism based on activity-dependent methylation of chemoreceptors. It has been argued that this architecture ensures precise and robust adaptation regardless of the ambient ligand concentration, making perfect adaptation a celebrated property of the chemotaxis system. However, possible deviations from such ideal adaptive behavior and its consequences for chemotaxis have not been explored in detail. Here we show that the chemotaxis pathway in Escherichia coli shows increasingly imprecise adaptation to higher concentrations of attractants, with a clear correlation between the time of adaptation to a step-like stimulus and the extent of imprecision. Our analysis suggests that this imprecision results from a gradual saturation of receptor methylation sites at high levels of stimulation, which prevents full recovery of the pathway activity by violating the conditions required for precise adaptation. We further use computer simulations to show that limited imprecision of adaptation has little effect on the rate of chemotactic drift of a bacterial population in gradients, but hinders precise accumulation at the peak of the gradient. Finally, we show that for two major chemoeffectors, serine and cysteine, failure of adaptation at concentrations above 1 mM might prevent bacteria from accumulating at toxic concentrations of these amino acids