Spatial scales of variance in abundance of intertidal species: effects of region, dispersal mode, and trophic level

Abstract The implementation of food web criteria in the Marine Strategy Framework Directive context faces several difficulties, namely the lack of data for relevant taxa, the absence of operational indicators, and spatially and temporally limited datasets. This work aims to identify ecologically relevant scales in the Celtic Seas (CS) and the Bay of Biscay and Iberian Coast (BBIC). Four food web criteria—mean trophic level (MTL), mean trophic level with cut-offs (MTL_3.25 and MTL_4), large fish indicator (LFI) and mean abundance across trophic guild (MATG)—were assessed using groundfish data and tested using generalized additive models, for six spatial scales and four temporal scales. In both subregions, MTL required yearly and locally defined assessment scales. As for MTL_3.25, it improved significantly when downsizing spatial scales but was temporally consistent. In the CS, locally defined scales and yearly data explained MTL_4 and LFI. While in BBIC, MTL_4 and LFI patterns were defined spatially by region and depth and temporally by year. MATG variability was unaffected by scales. Using the scales identified, food web criteriawere assessed for the Portuguese continental waters. Criteria failed to achieve Good Environmental Status in areas of the Southwest and South of Portugal. Although downsizing scales revealed that criteria were below the threshold at local/regional level, differences in classification are expected to be limited if spatial assessments are aggregated.

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Spatial scales of population synchrony of two competing species: effects of harvesting and strength of competition

Oikos ◽

10.1111/oik.05069 ◽

2018 ◽

Vol 127 (10) ◽

pp. 1459-1470 ◽

Cited By ~ 4

Author(s):

Javier Jarillo ◽

Bernt-Erik Saether ◽

Steinar Engen ◽

Francisco J. Cao

Keyword(s):

Spatial Scales ◽

Competing Species ◽

Population Synchrony ◽

Species Effects ◽

Strength Of Competition

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Towards coherent GES assessments at sub-regional level: signs of fisheries expansion processes in the Bay of Biscay using an OSPAR food web indicator, the mean trophic level

ICES Journal of Marine Science ◽

10.1093/icesjms/fsz023 ◽

2019 ◽

Vol 76 (6) ◽

pp. 1543-1553 ◽

Cited By ~ 2

Author(s):

Nina-Larissa Arroyo ◽

Georges Safi ◽

Pauline Vouriot ◽

Lucía López-López ◽

Nathalie Niquil ◽

...

Keyword(s):

Trophic Level ◽

Spatial Scales ◽

Management Strategies ◽

Regional Level ◽

Bay Of Biscay ◽

Ecosystem Studies ◽

The Mean ◽

Mean Trophic Level ◽

Over Exploitation

Abstract Using the Bay of Biscay (BoB) as a case study, we conducted a transnational assessment of the mean trophic level (MTL, Ospar FW4) indicator at sub-regional level, over the last three decades. Our results confirm the apparent recovery of BoB’s bentho-demersal system, as shown by trends in the MTL indicator based on survey data. However, they also point at a concomitant “fishing through” process where the apparent stability revealed by the MTL indicator based on landed catch data may be masking the expansion of demersal fisheries to deeper waters, and an over-exploitation of resources (particularly abundant pelagic species). Moreover, they show how the combined examination of independent surveys and fishery landings allows the identification of ecological trends in ecosystem studies. In addition, our results confirm that analysing MTL at various threshold levels helps discerning the causality of trends in this indicator, especially if analyses for pelagic and demersal species are run independently. Further studies, at smaller (i.e. local) spatial scales, need to be conducted to ascertain our results and suggest appropriate management strategies aimed at regulating fisheries expansions in the area.

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High spatial resolution x-ray microanalysis of interfaces

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100137793 ◽

1995 ◽

Vol 53 ◽

pp. 284-285

Author(s):

J. R. Michael

Keyword(s):

Spatial Resolution ◽

Electron Probe ◽

Solid Angle ◽

Collection Efficiency ◽

Spatial Scales ◽

Energy Dispersive Spectrometer ◽

X Rays ◽

X Ray ◽

Probe Size ◽

Brightness Field

X-ray microanalysis in the analytical electron microscope (AEM) refers to a technique by which chemical composition can be determined on spatial scales of less than 10 nm. There are many factors that influence the quality of x-ray microanalysis. The minimum probe size with sufficient current for microanalysis that can be generated determines the ultimate spatial resolution of each individual microanalysis. However, it is also necessary to collect efficiently the x-rays generated. Modern high brightness field emission gun equipped AEMs can now generate probes that are less than 1 nm in diameter with high probe currents. Improving the x-ray collection solid angle of the solid state energy dispersive spectrometer (EDS) results in more efficient collection of x-ray generated by the interaction of the electron probe with the specimen, thus reducing the minimum detectability limit. The combination of decreased interaction volume due to smaller electron probe size and the increased collection efficiency due to larger solid angle of x-ray collection should enhance our ability to study interfacial segregation.

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Kinetic parameters of nitrate uptake by different catch crop species: effects of low temperatures or previous nitrate starvation

Physiologia Plantarum ◽

10.1034/j.1399-3054.1993.880112.x ◽

1993 ◽

Vol 88 (1) ◽

pp. 85-92 ◽

Cited By ~ 1

Author(s):

P Laine ◽

A. Ourry ◽

J. Macduff ◽

J. Boucaud ◽

J. Salette

Keyword(s):

Kinetic Parameters ◽

Low Temperatures ◽

Nitrate Uptake ◽

Catch Crop ◽

Crop Species ◽

Species Effects ◽

Nitrate Starvation

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Spatial regularities between non-immigrant and immigrant numbers in Canada

MIGRATION LETTERS ◽

10.33182/ml.v11i1.171 ◽

2014 ◽

Vol 11 (1) ◽

pp. 90-100

Author(s):

Yigit Aydede

Keyword(s):

Fixed Effects ◽

Spatial Scales ◽

National Scale ◽

Pooled Data

The present study intends to reveal spatial regularities between non-immigrant and immigrant numbers in two different ways. First, it questions the existence of those regularities when spatial scales get finer. Second, it uses pooled data over four population censuses covering the period from 1991 to 2006, which enabled us to apply appropriate techniques to remove those unobserved fixed effects so that the estimations would accurately identify the linkage between local immigrant and non-immigrant numbers. The results provide evidence about the existence of negative spatial regularities between non-immigrant and immigrant numbers in Canada at national scale.

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Relationship between morphometrics and trophic levels in deep-sea fishes

Marine Ecology Progress Series ◽

10.3354/meps13243 ◽

2020 ◽

Vol 637 ◽

pp. 225-235 ◽

Cited By ~ 1

Author(s):

MA Ladds ◽

MH Pinkerton ◽

E Jones ◽

LM Durante ◽

MR Dunn

Keyword(s):

Stable Isotopes ◽

Trophic Level ◽

Deep Sea ◽

Strong Relationship ◽

Ecosystem Model ◽

Trophic Levels ◽

Fish Size ◽

Wide Range ◽

Gape Size ◽

Morphological Variables

Marine food webs are structured, in part, by predator gape size. Species found in deep-sea environments may have evolved such that they can consume prey of a wide range of sizes, to maximise resource intake in a low-productivity ecosystem. Estimates of gape size are central to some types of ecosystem model that determine which prey are available to predators, but cannot always be measured directly. Deep-sea species are hypothesized to have larger gape sizes than shallower-water species relative to their body size and, because of pronounced adaptive foraging behaviour, show only a weak relationship between gape size and trophic level. Here we present new data describing selective morphological measurements and gape sizes of 134 osteichthyan and chondrichthyan species from the deep sea (200-1300 m) off New Zealand. We describe how gape size (height, width and area) varied with factors including fish size, taxonomy (class and order within a class) and trophic level estimated from stable isotopes. For deep-sea species, there was a strong relationship between gape size and fish size, better predicted by body mass than total length, which varied by taxonomic group. Results show that predictions of gape size can be made from commonly measured morphological variables. No relationship between gape size and trophic level was found, likely a reflection of using trophic level estimates from stable isotopes as opposed to the commonly used estimates from FishBase. These results support the hypothesis that deep-sea fish are generalists within their environment, including suspected scavenging, even at the highest trophic levels.

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