scholarly journals Stability of the relationships among demersal fish assemblages and environmental-trawling drivers at large spatio-temporal scales in the northern Mediterranean Sea

2020 ◽  
Vol 83 (S1) ◽  
pp. 153
Author(s):  
Bastien Mérigot ◽  
Jean Claude Gaertner ◽  
Anik Brind’Amour ◽  
Pierluigi Carbonara ◽  
Antonio Esteban ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Environmental Changes ◽  
Fish Assemblages ◽  
Environmental Gradients ◽  
Temporal Stability ◽  
Demersal Fish ◽  
Minor Role ◽  
Carbon Biomass ◽  
Spatio Temporal ◽  
A Minor

Trawling pressure and environmental changes may affect the composition of fish assemblages. Our knowledge on large spatio-temporal patterns of demersal fish composition remains incomplete for the Mediterranean Sea. We investigated (1) the spatio-temporal stability of demersal assemblages, (2) the relationships between these assemblages and potential structuring factors (trawling pressure and environmental conditions) in order to assess the dynamic of the assemblage structure at the scale of the northern Mediterranean Sea. We analysed a dataset of 18062 hauls from 10 to 800 m depth performed annually during the last two decades across 17 Geographical Sub-Areas (GSAs) (MEDITS program). A multi-table analysis (STATICO-CoA) evidenced a strong inter-GSAs stability in the organization of assemblages, with specificities for some GSAs. The most stable structuring factors were linked to combined gradients of chlorophyll a, phytoplancton carbon biomass and temperature, inversely correlated with depth, salinity and nutrient gradients (axis 1 of the STATICO-CoA compromise, 93.74% of the total variability). A common pattern linking the distribution of species to these environmental gradients was evidenced for most of the 17 GSAs. Estimate of trawling pressure showed a minor role in the organization of the assemblages for the spatial scale and years investigated (axis 2, 4.67%).

scholarly journals Large-scale spatio-temporal monitoring highlights hotspots of demersal fish diversity in the Mediterranean Sea

2015 ◽  
Vol 130 ◽  
pp. 65-74 ◽  
Author(s):  
Victoria Granger ◽  
Jean-Marc Fromentin ◽  
Nicolas Bez ◽  
Giulio Relini ◽  
Christine N. Meynard ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Large Scale ◽  
Demersal Fish ◽  
Fish Diversity ◽  
The Mediterranean ◽  
Spatio Temporal

Corrigendum to ‘‘Large-scale spatio-temporal monitoring highlights hotspots of demersal fish diversity in the Mediterranean Sea” [Prog. Oceanogr. 130 (2015) 65–74]

2015 ◽  
Vol 138 ◽  
pp. 322-323 ◽  
Author(s):  
Victoria Granger ◽  
Jean-Marc Fromentin ◽  
Nicolas Bez ◽  
Giulio Relini ◽  
Christine N. Meynard ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Large Scale ◽  
Demersal Fish ◽  
Fish Diversity ◽  
The Mediterranean ◽  
Spatio Temporal

scholarly journals Effects of natural and anthropogenic environmental changes on riverine fish assemblages: a framework for ecological assessment of rivers

2005 ◽  
Vol 48 (1) ◽  
pp. 91-108 ◽  
Author(s):  
Francisco Leonardo Tejerina-Garro ◽  
Mabel Maldonado ◽  
Carla Ibañez ◽  
Didier Pont ◽  
Nicolas Roset ◽  
...  
Keyword(s):  
Environmental Changes ◽  
Fish Assemblages ◽  
Environmental Gradients ◽  
Geographic Area ◽  
Ecological Assessment ◽  
Natural Conditions ◽  
Detailed Understanding ◽  
Assemblage Composition ◽  
Ecological Regions ◽  
Riverine Fish

Freshwater is a basic need for the mankind. Effective biological tools (ecologically based, efficient, rapid and consistently applicable to different ecological regions) are needed to measure the "health" of rivers. Adapting such tools over a broad geographic area requires a detailed understanding of both the patterns of organisms assemblage composition and distribution within and among water bodies under natural conditions, and the nature of the major environmental gradients that cause or explain these patterns. A comprehensive review of the available litterature dealing with the identification of environmental factors structuring riverine fish assemblages under natural conditions permits to identify the most consistent ones.

scholarly journals Spatial and temporal trend in the abundance and distribution of gurnards (Pisces: Triglidae) in the northern Mediterranean Sea

2020 ◽  
Vol 83 (S1) ◽  
pp. 101
Author(s):  
Francesco Colloca ◽  
Giacomo Milisenda ◽  
Francesca Capezzuto ◽  
Alessandro Cau ◽  
Germana Garofalo ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Fish Assemblages ◽  
Linear Trend ◽  
Temporal Trends ◽  
Temporal Distribution ◽  
Demersal Fish ◽  
Western Mediterranean ◽  
Trawl Survey ◽  
Coastal Species ◽  
The Impact

In this study we investigated the spatio-temporal distribution of gurnards (8 species of Triglidae and one species of Peristediidae) in the northern Mediterranean Sea using 22 years of MEDITS bottom trawl survey data (1994-2015). Gurnards showed significant differences in terms of abundance, dominance and composition among geographical sub-areas and ecoregions, with the highest relative biomass (BIy) being found in Malta, eastern Corsica, the Balearic Islands and the eastern Ionian Sea. The lowest gurnards BIy were observed in the highly exploited areas of the western Mediterranean and the Adriatic Sea, where the largest number of species with a negative linear trend in BIy was also found. The temporal trends in species abundances highlighted a general decrease for the coastal species (C. lucerna, C. lastoviza, C. obscurus) as compared with the species inhabiting the deep continental shelf and slope (T. lyra, P. cataphractum). The results provide for the first time an overview of the spatiotemporal trend in the abundance of gurnards over the wide spatial scale of the northern Mediterranean Sea, also suggesting the possible use of these species as indicators for monitoring the impact of fishing pressure on demersal fish assemblages.

Demersal Fish Assemblages on the Scotian Shelf, Northwest Atlantic: Spatial Distribution and Persistence

1989 ◽  
Vol 46 (S1) ◽  
pp. s134-s152 ◽  
Author(s):  
Robin Mahon ◽  
Robert W. Smith
Keyword(s):  
Environmental Variables ◽  
Fishery Management ◽  
Fish Assemblages ◽  
Environmental Gradients ◽  
Demersal Fish ◽  
Assemblage Structure ◽  
Bay Of Fundy ◽  
Scotian Shelf ◽  
Species Groups ◽  
Temporal And Spatial

This study is based on 18 surveys, 12 in summer, and three each in spring and fall, with bottom trawls over the Scotian Shelf and Bay of Fundy. The data analysis sequence was: temporal and spatial aggregation of trawl sets; estimation of interspecies and intersite distance indices; clustering and ordination of sites and species, and discrimination of site groups using environmental variables. Nine species-groups, and 10 site-groups were defined, and displayed in a two-way table. Depth and temperature were the environmental variables most strongly associated with differences in assemblage structure among site-groups. Changes in assemblage structure from one area to another were distinct but apparently gradual, with no sharp assemblage boundaries. This pattern is expected if species are distributed independently on environmental gradients, rather than if assemblages consist of highly co-evolved, interdependent species. The observed spatial patterns were highly persistent through time. There are regions which are relatively homogeneous with regard to species composition and which can therefore be useful in dealing with bycatch problems. However, this study does not indicate the existence of discrete assemblages which might be appropriate as ecologically based fishery management units.

Spatio-temporal variations in demersal fish assemblages and diversity in the northern Gulf of St. Lawrence (Canada)

2014 ◽  
Vol 36 (3) ◽  
pp. 557-571 ◽  
Author(s):  
Hacène Tamdrari ◽  
Jean-Claude Brêthes ◽  
Diane Archambault
Keyword(s):  
Fish Assemblages ◽  
Demersal Fish ◽  
Temporal Variations ◽  
Spatio Temporal

scholarly journals Multi-scale statistics of turbulence motorized by active matter

2017 ◽  
Vol 822 ◽  
pp. 762-773 ◽  
Author(s):  
J. Urzay ◽  
A. Doostmohammadi ◽  
J. M. Yeomans
Keyword(s):  
Turbulent Flows ◽  
Three Dimensional ◽  
Collective Effects ◽  
Minor Role ◽  
Activity Levels ◽  
Active Matter ◽  
Multi Scale ◽  
Spatio Temporal ◽  
High Reynolds ◽  
A Minor

A number of micro-scale biological flows are characterized by spatio-temporal chaos. These include dense suspensions of swimming bacteria, microtubule bundles driven by motor proteins and dividing and migrating confluent layers of cells. A characteristic common to all of these systems is that they are laden with active matter, which transforms free energy in the fluid into kinetic energy. Because of collective effects, the active matter induces multi-scale flow motions that bear strong visual resemblance to turbulence. In this study, multi-scale statistical tools are employed to analyse direct numerical simulations (DNS) of periodic two-dimensional (2-D) and three-dimensional (3-D) active flows and to compare the results to classic turbulent flows. Statistical descriptions of the flows and their variations with activity levels are provided in physical and spectral spaces. A scale-dependent intermittency analysis is performed using wavelets. The results demonstrate fundamental differences between active and high-Reynolds-number turbulence; for instance, the intermittency is smaller and less energetic in active flows, and the work of the active stress is spectrally exerted near the integral scales and dissipated mostly locally by viscosity, with convection playing a minor role in momentum transport across scales.

The Effect of Path Length and Display Size on Memory for Spatial Information

2012 ◽  
Vol 59 (3) ◽  
pp. 147-152 ◽  
Author(s):  
Katherine Guérard ◽  
Sébastien Tremblay
Keyword(s):  
Path Length ◽  
Potential Role ◽  
Spatial Information ◽  
Recall Performance ◽  
Minor Role ◽  
Length Effect ◽  
Serial Memory ◽  
Fixed Reference ◽  
A Minor

In serial memory for spatial information, some studies showed that recall performance suffers when the distance between successive locations increases relatively to the size of the display in which they are presented (the path length effect; e.g., Parmentier et al., 2005) but not when distance is increased by enlarging the size of the display (e.g., Smyth & Scholey, 1994). In the present study, we examined the effect of varying the absolute and relative distance between to-be-remembered items on memory for spatial information. We manipulated path length using small (15″) and large (64″) screens within the same design. In two experiments, we showed that distance was disruptive mainly when it is varied relatively to a fixed reference frame, though increasing the size of the display also had a small deleterious effect on recall. The insertion of a retention interval did not influence these effects, suggesting that rehearsal plays a minor role in mediating the effects of distance on serial spatial memory. We discuss the potential role of perceptual organization in light of the pattern of results.

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