Diamondback terrapin mortality in the American eel pot fishery and evaluation of a bycatch reduction device

The effect of commercial fisheries on nontarget species is a burgeoning issue for both fishery managers and estuarine biologists. We documented diamondback terrapin (Malaclemys terrapin) bycatch in cloth-funnel eel pots used in a Maryland (United States) commercial American eel (Anguilla rostrata) fishery. Between 1992 and 2001, we obtained 40 male and 9 female terrapin captures and 1 male terrapin recapture from commercial eel pots. To quantify terrapin catch rates and evaluate a potential solution to terrapin bycatch in eel pots, we conducted two experiments that tested the effects of a novel cel pot bycatch reduction device on terrapin bycatch and eel harvest. We determined low terrapin bycatch rates (0.000–0.008 terrapins pot⁻¹ d⁻¹) in pots with small entrance funnels and high terrapin capture rates (0.458 terrapins pot⁻¹ d⁻¹) in pots with large entrance funnels. The BRD eliminated terrapin bycatch and had no effect on eel catch making it an economically-viable solution for terrapin mortality in eel pots. We demonstrated that terrapin bycatch can be a problem in the American eel pot fishery and that our bycatch reduction device is a simple and cost-effective solution to this problem.     

Estimating long-term cliff recession rates from shore platform widths

Coastal cliff erosion is a problem in many coastal areas. However, often only very limited data are available to quantify the rates of recession for the development of coastal management strategies. In the soft flysch deposits of the Waitemata Group, Auckland, New Zealand, coastal cliffs are associated with shore platforms. Two models exist for the profile evolution of shore platforms and associated cliffs: the first suggests that an equilibrium profile develops in response to erosive processes, and this profile subsequently migrates landward; the second model suggests that the seaward margin of the shore platform is relatively static, and the profile extends landward through a combination of cliff recession and platform lowering. Physical simulations and field measurements for mudstone and limestone lithologies indicate that the second model is more likely for soft flysch deposits. A eustatic sea-level curve for the Weiti Estuary, Auckland, suggests that up to 7120 ± 70 years have been available for shore platform development since sea level reached the present seaward margins of shore platforms. Shore platform widths were measured using GPS at two sites in Waitemata Group rocks: the North Shore of Auckland; and the southern side of the Tawharanui Peninsula, North Auckland. The long-term cliff recession rates estimated from shore platform widths (1.4 ± 0.1 to 14.3 ± 0.1 mm y^− 1) are consistent with the lower end of the average range of cliff top and face recession rates published for Waitemata Group rocks using different methods (11–75 mm y^− 1), and in agreement with cliff base recession estimates (3.5 mm y^− 1). Shore platform widths were qualitatively related to the rock mass characteristics of the associated cliffs, and therefore platform widths could provide a method of identifying regions of potential hazard.     

A mathematical model for orientation data from macroscopic cylindrical folds

An asymptotic form of Bingham's distribution on the sphere is applied to orientation data from cylindrical folds. Data from cylindrical folds typically form two clusters, one cluster for each fold limb. A bimodal distribution is obtained by fitting a unimodal distribution to each cluster. One parameter of the distribution gives the fold axis, another parameter is directly related to the curvature of the fold limb. Certain tests of hypotheses based on this distribution are the same as tests based on the Dimroth—Watson (symmetric girdle)distribution. One such is the test of whether two folds have the same fold axis.     

Using Statistical Learning Algorithms in Regional Landslide Susceptibility Zonation with Limited Landslide Field Data

Regional Landslide Susceptibility Zonation(LSZ) is always challenged by the available amount of field data, especially in southwestern China where large mountainous areas and limited field information coincide. Statistical learning algorithms are believed to be superior to traditional statistical algorithms for their data adaptability. The aim of the paper is to evaluate how statistical learning algorithms perform on regional LSZ with limited field data. The focus is on three statistical learning algorithms, Logistic Regression(LR), Artificial Neural Networks(ANN) and Support Vector Machine(SVM). Hanzhong city, a landslide prone area in southwestern China is taken as a study case. Nine environmental factors are selected as inputs. The accuracies of the resulting LSZ maps are evaluated through landslide density analysis(LDA), receiver operating characteristic(ROC) curves and Kappa index statistics. The dependence of the algorithm on the size of field samples is examined by varying the sizes of the training set. The SVM has proven to be the most accurate and the most stable algorithm at small training set sizes and on all known landslide sizes. The accuracy of SVM shows a steadilyincreasing trend and reaches a high level at a small size of the training set, while accuracies of LR and ANN algorithms show distinct fluctuations. The geomorphological interpretations confirm the strength of SVM on all landslide sizes. Our results show that the strengths of SVM in generalization capability and model robustness make it an appropriate and efficient tool for regional LSZ with limited landslide field samples.     

A kinematic study of the integral shaped filament:what roles do filaments play in forming young stellar clusters?

Young protoclusters(embedded stellar clusters) are responsible for the vast majority of star formation currently occurring in the Galaxy. Recent observations suggest a scenario in which filamentary structures in the interstellar medium represent the first step towards precluster clumps and eventually star formation. Whether filaments continuously fuel the star formation process when the cluster accretes material is still an open question. In this paper, we present a case study of the famous ‘integral shaped filament'(ISF) in the Orion A molecular cloud and we seek to study the kinematics which is truly originated from the ISF. We firstly define the central ridge of the ISF with NH_3,~(12) CO,~(13) CO and N_2H~+. Undulations are present in all the ridges. Moreover, a large scale offset is apparent in the ridges as derived by different tracers, which may be explained by the slingshot mechanism proposed by Stutz Gould. We fit the velocity field of the ISF and find the derived velocity gradient is about 0.7 km s~(-1) pc~(-1) which may come from an overall contraction. We propose a method to check the accretion flow along the ISF by using the velocity deviations of different molecular tracers, which is better than the common method of using the velocity distribution of one tracer alone. Using the velocity deviations, we also find that OMC-1 to 5 are located close to the local extrema of the fluctuations, which may demonstrate that gas flows toward each clump along the ISF.