Mapping fish community biodiversity for European marine policy requirements

2017 ◽  
Vol 74 (8) ◽  
pp. 2223-2238
Author(s):  
Henrike Rambo ◽  
Vanessa Stelzenmüller ◽  
Simon P. R. Greenstreet ◽  
Christian Möllmann
Keyword(s):  
Species Distributions ◽  
Relevant Information ◽  
Demersal Fish ◽  
Marine Conservation ◽  
Direct Approach ◽  
Individual Species ◽  
Marine Policy ◽  
Biodiversity Indicators ◽  
Indirect Approach ◽  
Distribution Maps

Abstract Predictive maps of biodiversity patterns are pivotal to marine conservation and marine spatial planning alike, yet mapping of biodiversity indicators at the community-level is neither straightforward nor well-tested empirically. Two principle approaches exist. A direct approach involves calculation of indices for each sample, followed by interpolation to estimate values at unsampled locations. An indirect approach first interpolates individual species distributions and then determines indices based on the stacked distribution maps. We compared the appropriateness of both approaches to provide management-relevant information by mapping the distribution of demersal fish biodiversity in the German North Sea Exclusive Economic Zone using species richness, Hill’s N1 and a novel traits-based community sensitivity to fishing index (CSI). To substitute zero-inflated species with up to 95% zeros in the sample data, we applied each species’ mean abundance value as a flat surface. Spatial patterns between indicators varied, but certain hot- and cold-spots were revealed, which, under current legislation, might suggest that the present level of biodiversity protection is insufficient. Despite both approaches generating similar main patterns, the direct approach predicted a narrower range of index values and only depicted the most dominant patterns. Contrary to that the indirect approach better reproduced the variability in the data, along with additional information on species distributions and a theoretical advantage pertaining to sampling issues. Although the choice over the mapping approach is context dependent, for our study area featuring a community with relatively few species, we consider the indirect approach to provide the more reliable information for implementing marine environmental legislation.

Rates of retained and discarded catches from demersal fish trawling off the north-eastern United States

1997 ◽  
Vol 48 (3) ◽  
pp. 185 ◽  
Author(s):  
S. J. Kennelly ◽  
S. C. Drew ◽  
C. D. Delano Gagnon
Keyword(s):  
United States ◽  
Large Scale ◽  
Demersal Fish ◽  
Statistical Analyses ◽  
Individual Species ◽  
Eastern United States ◽  
Spatial And Temporal Patterns ◽  
The North ◽  
North Eastern ◽  
Catch Rates

The retained- and discarded-catch rates of fish, crustaceans and molluscs caught by demersal fish trawlers were quantified in a large-scale observer survey of fleets working off the north-eastern United States. The data presented come from catches sampled from 7757 tows on 1010 fishing trips during the four-year period from July 1990 to June 1994 and are summarized as the weights retained and discarded (per hour of trawling) for many of the important commercial and recreational species in the region. Problems with the spatial and temporal design of the programme restricted statistical analyses of the data and prevented summaries across all statistical areas and months. However, separate summaries for individual areas (over all months) and individual months (over all areas) identified several spatial and temporal patterns in retained- and discarded-catch rates for individual species and combinations of species. Noticeable increases and decreases in catch rates during the four-year period provided information on the relative health of certain stocks, and overall discard percentages indicated relative selectivities of the trawling operations sampled.

Logarithmic and exponential functions —a direct approach

1959 ◽  
Vol 52 (6) ◽  
pp. 439-443
Author(s):  
C. L. Seebeck ◽  
P. M. Hummel
Keyword(s):  
Secondary School ◽  
Exponential Function ◽  
Secondary School Students ◽  
Direct Approach ◽  
Exponential Functions ◽  
School Students ◽  
Indirect Approach

A direct approach to logarithms rather than the indirect approach as an inverse of an exponential function has many advantages for teaching secondary school students.

scholarly journals Trends in cpue and related changes in spatial distribution of demersal fish species in the Kattegat and Skagerrak, eastern North Sea, between 1981 and 2003

2005 ◽  
Vol 62 (4) ◽  
pp. 671-682 ◽  
Author(s):  
Michele Casini ◽  
Massimiliano Cardinale ◽  
Joakim Hjelm ◽  
Francesca Vitale
Keyword(s):  
Spatial Distribution ◽  
Fish Species ◽  
General Pattern ◽  
Demersal Fish ◽  
Average Weight ◽  
Trawl Survey ◽  
Catch Per Unit Effort ◽  
Distribution Maps ◽  
Increasing Trend ◽  
Commercial Species

Abstract We explored the trends in ln-transformed catch per unit effort, defined as average weight (kg) per 1 h trawling, and the spatial distribution of 32 demersal fish species in the Kattegat and Skagerrak using International Bottom Trawl Survey data collected between 1981 and 2003. As in other areas, the biomass of roundfish species such as cod, pollack, hake, and ling drastically decreased during this period most likely owing to fishing pressure. However, other commercially important fish species, e.g. haddock, whiting, and some flatfish, showed a constant or increasing trend during the same period. Non-commercial species showed no or an increasing trend in ln-cpue, by as much as 40 times in hagfish. Furthermore, analyses of the spatial distribution of 14 selected fish species by means of distribution maps of ln-cpue suggested that fish stocks contracted and expanded in response to decrease and increase of the stock biomass, respectively, with some flatfish species (i.e. plaice and flounder) and hagfish representing the exceptions to this general pattern.

scholarly journals Comparison of spatial association approaches for landscape mapping of soil organic carbon stocks

2014 ◽  
Vol 1 (1) ◽  
pp. 757-802 ◽  
Author(s):  
B. A. Miller ◽  
S. Koszinski ◽  
M. Wehrhan ◽  
M. Sommer
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Spatial Variation ◽  
Spatial Association ◽  
Direct Approach ◽  
Indirect Approach ◽  
Global Issues ◽  
Soc Stock ◽  
Estimated Error ◽  
Soc Stocks

Abstract. The distribution of soil organic carbon (SOC) can be variable at small analysis scales, but consideration of its role in regional and global issues demands the mapping of large extents. There are many different strategies for mapping SOC, among which are to model the variables needed to calculate the SOC stock indirectly or to model the SOC stock directly. The purpose of this research is to compare direct and indirect approaches to mapping SOC stocks from rule-based, multiple linear regression models applied at the landscape scale via spatial association. The final products for both strategies are high-resolution maps of SOC stocks (kg m−2), covering an area of 122 km2, with accompanying maps of estimated error. For the direct modelling approach, the estimated error map was based on the internal error estimations from the model rules. For the indirect approach, the estimated error map was produced by spatially combining the error estimates of component models via standard error propagation equations. We compared these two strategies for mapping SOC stocks on the basis of the qualities of the resulting maps as well as the magnitude and distribution of the estimated error. The direct approach produced a map with less spatial variation than the map produced by the indirect approach. The increased spatial variation represented by the indirect approach improved R2 values for the topsoil and subsoil stocks. Although the indirect approach had a lower mean estimated error for the topsoil stock, the mean estimated error for the total SOC stock (topsoil + subsoil) was lower for the direct approach. For these reasons, we recommend the direct approach to modelling SOC stocks be considered a more conservative estimate of the SOC stocks' spatial distribution.

scholarly journals Metaphors for marine conservation and management: The good, the bad, and the inaccurate

2018 ◽  
Author(s):  
OCTO
Keyword(s):  
Marine Conservation ◽  
Marine Policy ◽  
Or Management ◽  
Figures Of Speech ◽  
Oppositional Behaviors ◽  
Ocean Ecosystems ◽  
Conservation And Management

A new paper in Marine Policy discusses the importance of effective metaphors for marine conservation and policy. Metaphors are figures of speech that describe something in terms more familiar to listeners, e.g., “a blanket of snow”. Good metaphors help shape understanding of something and can mobilize appropriate action. Poorly-chosen metaphors are, at best, ineffective at mobilizing support for the intended cause, and, at worst, counterproductive because they lead to oppositional behaviors or decrease the credibility of the messenger. To be a good metaphor for marine conservation or management (or any other purpose really), a metaphor must be mapped onto something that is: 1) familiar, 2) appropriately evocative/relatable for a particular culture, and 3) scientifically accurate. Appropriate metaphors are especially important in marine conservation and management because the oceans seem remote to many people, and the scale and scope of threats to ocean ecosystems can be difficult to understand and relate to.

DETERMINATION OF A LAW APPLICABLE TO THE SUBSTANCE OF A DISPUTE BY THE ARBITRATION TRIBUNAL IN THE PROCESS OF RESOLUTION OF INTERNATIONAL COMMERCIAL DISPUTES

2017 ◽  
Author(s):  
Volodymyr Nahnybida ◽  
Keyword(s):  
Direct Approach ◽  
Specific Reference ◽  
Private International Law ◽  
Arbitral Tribunal ◽  
Indirect Approach ◽  
Conflict Of Laws ◽  
The Difference ◽  
Definition Of ◽  
The Right ◽  
Substantive Law

The article examines the main approaches to the determination by the arbitral tribunal, in the absence of a choice of parties, of a substantive law applicable to the merits of a dispute, when resolving disputes in international commercial arbitration. It is noted that the three fundamental approaches to the establishment by the arbitral tribunal of the law applicable to the merits of the dispute include: 1) the application by the arbitrators of the principle of the closest connection; 2) recourse to conflict-of-laws rules that the arbitral tribunal considers applicable (indirect approach, voie indirecte) 3) granting arbitrators the right to directly establish and apply substantive law without resorting to any conflict-of-laws or rules (the so-called voie directe or direct approach). It is summarized that all of the above approaches are aimed at ensuring the compliance of the applicable substantive law established by the arbitral tribunal with the substance of the dispute and the subject of the contract, especially the first two related to conflict of laws – both with a specific reference to law, which has the closest connections with legal relations, and with the ability of the arbitrators to refer to other conflict-of-laws rules that it deems applicable. The difference concerning the third of the approaches, voie directe or direct choice of the applicable law, lies in the greater degree of freedom of the arbitrators in this matter, since the obligation of the arbitral tribunal to refer to the conflict of laws rules of a certain national system of private international law or transnational conflict of laws is generally eliminated. The author claims that the arbitral tribunal, depending on the approach adopted in the country of place of arbitration, whose mandatory provisions determine the procedure for the arbitrators to establish the applicable substantive law in the absence of a choice of parties, and the rules enshrined in the arbitration rules of the relevant institution, can either independently establish such a right (direct approach) or turn first to the definition of applicable conflict of laws rules, according to which the choice of substantive law will be made (indirect approach). Such conflict-of-laws links, as a rule, include: the principle of the closest connection, the country of the place of performance of the contract, the country of location of the party that must carry out significant performance, etc.

Mapping species distributions as a tool in marine ecology

1978 ◽  
Vol 76 (1-3) ◽  
pp. 201-213 ◽  
Author(s):  
Trevor A. Norton
Keyword(s):  
Environmental Factors ◽  
Distribution Pattern ◽  
Experimental Work ◽  
Current Velocity ◽  
Species Distributions ◽  
Distribution Patterns ◽  
Marine Species ◽  
Marine Ecology ◽  
Distribution Maps ◽  
Geographical Scale

SynopsisMaps are shown to be the most striking way of displaying the distribution of marine species on a geographical scale. They have been used to indicate not only the presence or absence of a species, but also its abundance. A single map only records the distribution pattern at a particular moment in time, but repeated mapping clearly demonstrates temporal fluctuations. Many ecological insights have been derived from distribution maps especially when they are compared with records of environmental factors such as substratum type, current velocity or temperature. Moreover maps actually stimulate experimental work which seeks to explain the distribution patterns displayed.

scholarly journals Spatial prediction of demersal fish distributions: enhancing our understanding of species–environment relationships

2009 ◽  
Vol 66 (9) ◽  
pp. 2068-2075 ◽  
Author(s):  
Cordelia H. Moore ◽  
Euan S. Harvey ◽  
Kimberly P. Van Niel
Keyword(s):  
Environmental Variables ◽  
Spatial Ecology ◽  
Predictive Accuracy ◽  
Species Distributions ◽  
Spatial Prediction ◽  
Accurate Method ◽  
Demersal Fish ◽  
Additive Models ◽  
Video Data ◽  
Fish Distributions

Abstract Moore, C. H., Harvey, E. S., and Van Niel, K. P. 2009. Spatial prediction of demersal fish distributions: enhancing our understanding of species–environment relationships. – ICES Journal of Marine Science, 66: 2068–2075. We used species distribution modelling to identify key environmental variables influencing the spatial distribution of demersal fish and to assess the potential of these species–environment relationships to predict fish distributions accurately. In the past, predictive modelling of fish distributions has been limited, because detailed habitat maps of deeper water (>10 m) have not been available. However, recent advances in mapping deeper marine environments using hydroacoustic surveys have redressed this limitation. At Cape Howe Marine National Park in southeastern Australia, previously modelled benthic habitats based on hydroacoustic and towed video data were used to investigate the spatial ecology of demersal fish. To establish the influence of environmental variables on the distributions of this important group of marine fish, classification trees (CTs) and generalized additive models (GAMs) were developed for four demersal fish species. Contrasting advantages were observed between the two approaches. CTs provided greater explained variation for three of the four species and revealed a better ability to model species distributions with complex environmental interactions. However, the predictive accuracy of the GAMs was greater for three of the four species. Both these modelling techniques provided a detailed understanding of demersal fish distributions and landscape linkages and an accurate method for predicting species distributions across unsampled locations where continuous spatial benthic data are available. Information of this nature will permit more-targeted fisheries management and more-effective planning and monitoring of marine protected areas.

Parameter Identification in an Inhomogeneous Medium With the Finite-Element Method

1976 ◽  
Vol 16 (04) ◽  
pp. 217-226 ◽  
Author(s):  
Y.S. Yoon ◽  
W.W-G. Yeh
Keyword(s):  
Differential Equation ◽  
Partial Differential Equation ◽  
Inverse Problem ◽  
Parameter Identification ◽  
Flow Region ◽  
Hyperbolic Type ◽  
Direct Approach ◽  
Partial Differential ◽  
Indirect Approach ◽  
Parameter Function

Abstract This paper studies the development of a systematic procedure for solving the problem of parameter identification. The parameter function to parameter identification. The parameter function to be identified is the permeability embedded in a nonlinear, partial differential equation of parabolic type. Finite elements are used to represent the unknown function parametrically in terms of nodal values over a suitable discretization of a flow region. These nodal values are then determined by a least-squares fitting between the observed and calculated flow potentials, subject to linear inequality constraints imposed upon the parameters to be identified. To handle such constraints, Rosen's gradient projection technique is combined with the Gauss-Newton method. Numerical procedures are presented for the solution of the procedures are presented for the solution of the partial differential equation using the Galerkin partial differential equation using the Galerkin method and a predictor-corrector approach. Simultaneous identification of 25 parameters embedded in a two-dimensional, nonlinear, diffusion-type equation is demonstrated by two examples. Introduction Mathematical models have been used as powerful tools in analyzing groundwater or oil reservoir systems. The application of such models to real field problems requires the determination of parameters embedded in partial differential parameters embedded in partial differential equations. These parameters are not simply measurable from die physical point of view. Recently, considerable attention has been directed toward developing analytical procedures for solving the parameter identification problem. Proposed methods may be classified into two Proposed methods may be classified into two groups: the direct approach and the indirect approach. The direct approach treats the parameters as dependent variables in the form of a formal boundary-value problem. If the flow potentials are known over the entire flow region, the original governing equation becomes a linear, first-order, partial differential equation of the hyperbolic type partial differential equation of the hyperbolic type in terms of the unknown permeability function. With the aid of boundary conditions and flow data, a unique solution of the equation can be obtained. Nelson and Nelson and McCollum proposed the energy dissipation method for solving the unknown parameters. Frind and Pinder used a Galerkin parameters. Frind and Pinder used a Galerkin method for steady flow only. Another direct-method approach that specially takes account of unsteady flow problems is the minimization of the residual error involved in the differential equation. When the error functional is defined as the sum or maximum norm, the minimization problem can be solved by the linear programming technique. The time component in a linear differential equation may be also eliminated by an integration with respect to time. This was studied by Nutbrown. When the flow data and necessary boundary conditions are lacking, the inverse problem yields an infinite number of possible solutions. The inverse problem, even in the case where its solution is guaranteed to be unique, is not generally well posed. In order to obtain a meaningful solution to the inverse problem, it is necessary to impose certain prior problem, it is necessary to impose certain prior restrictions on the admissible function space of parameters. The methods that have been proposed parameters. The methods that have been proposed in the literature include the use of a flatness criterion by Emsellem and de Marsilly and a multiple objective decision process by Neuman. For the direct approach a difficulty arises in the data requirement. In field practice, observation wells are sparsely distributed in an arbitrary fashion rather than regularly distributed; and only a limited number of wells are available. An attempt to obtain space and/or time derivative approximations of flow potentials from the insufficient data by finite-difference or finite-element methods would be a multisource of errors in the results of parameter identification. Sagar et al. suggested the method of spline interpolation to fit the discrete data of observations; but the method still requires a sufficient number of the observation points to adequately approximate the whole flow potential surface in the region under consideration. The indirect approach is an optimization procedure in which the algorithm starts from a set of initial estimates of the parameters and improves it in an iterative manner until the model response is sufficiently close to that of the field observation. SPEJ P. 217

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