scholarly journals Top-down local management, perceived contribution to people, and actual detriments influence a rampant human‒top predator conflict in the Neotropics

2021 ◽  
Author(s):  
Santiago Zuluaga ◽  
F. Hernán Vargas ◽  
Sebastián Kohn ◽  
Juan M. Grande
Keyword(s):  
Top Predator ◽  
Top Down ◽  
Local Management

scholarly journals Climate-induced changes in bottom-up and top-down processes independently alter a marine ecosystem

2012 ◽  
Vol 367 (1605) ◽  
pp. 2962-2970 ◽  
Author(s):  
Malte Jochum ◽  
Florian D. Schneider ◽  
Tasman P. Crowe ◽  
Ulrich Brose ◽  
Eoin J. O'Gorman
Keyword(s):  
Body Size ◽  
Body Mass ◽  
Nutrient Enrichment ◽  
Size Structure ◽  
Marine Ecosystem ◽  
Shore Crab ◽  
Top Predator ◽  
Top Down ◽  
Microalgal Biomass ◽  
Bottom Up

Climate change has complex structural impacts on coastal ecosystems. Global warming is linked to a widespread decline in body size, whereas increased flood frequency can amplify nutrient enrichment through enhanced run-off. Altered population body-size structure represents a disruption in top-down control, whereas eutrophication embodies a change in bottom-up forcing. These processes are typically studied in isolation and little is known about their potential interactive effects. Here, we present the results of an in situ experiment examining the combined effects of top-down and bottom-up forces on the structure of a coastal marine community. Reduced average body mass of the top predator (the shore crab, Carcinus maenas ) and nutrient enrichment combined additively to alter mean community body mass. Nutrient enrichment increased species richness and overall density of organisms. Reduced top-predator body mass increased community biomass. Additionally, we found evidence for an allometrically induced trophic cascade. Here, the reduction in top-predator body mass enabled greater biomass of intermediate fish predators within the mesocosms. This, in turn, suppressed key micrograzers, which led to an overall increase in microalgal biomass. This response highlights the possibility for climate-induced trophic cascades, driven by altered size structure of populations, rather than species extinction.

scholarly journals Should the Critically Endangered Goliath grouper Epinephelus itajara be culled in Florida?

Oryx ◽  
2012 ◽  
Vol 47 (1) ◽  
pp. 88-95 ◽  
Author(s):  
Sarah Frias-Torres
Keyword(s):  
Wildlife Conservation ◽  
Scientific Evidence ◽  
Economic Benefits ◽  
Top Predator ◽  
Top Down ◽  
Morphological Studies ◽  
The Usa ◽  
Goliath Grouper ◽  
Red Lionfish ◽  
National Marine Fisheries Service

AbstractThe Goliath grouper Epinephelus itajara has been protected in the USA since 1990. In Florida commercial and recreational fishers consider the species a top predator of fish and lobster and advocate culling the grouper population as a solution to recover declining stocks. I examined the scientific evidence for and against culling the Goliath grouper, using commercial landing data from the National Marine Fisheries Service and the Florida Fish and Wildlife Conservation Commission (1950–2010), fisheries-independent diver-based surveys from the REEF Environmental Education Foundation (1993–2007), and published dietary and morphological studies. An analysis of the commercial extinction of the Goliath grouper in Florida indicates that its recovering population is not the cause of declining fish and lobster stocks. The recovering Goliath grouper population could provide ecological and socio-economic benefits: as top-down control on other lobster predators, in ecotourism, and as potential biocontrol of the invasive Indo-Pacific red lionfish Pterois volitans on Atlantic reefs.

Invasion of a Top Predator into an Epipelagic Ecosystem can bring a Paradoxical Top-Down Trophic Control

2005 ◽  
Vol 7 (5) ◽  
pp. 845-861 ◽  
Author(s):  
Andrew Yu. Morozov ◽  
Nikolay P. Nezlin ◽  
Sergei V. Petrovskii
Keyword(s):  
Top Predator ◽  
Top Down

Top-Down Processing and Visual Reorientation Illusions in a Virtual Reality Environment

2004 ◽  
Vol 63 (3) ◽  
pp. 143-149 ◽  
Author(s):  
Fred W. Mast ◽  
Charles M. Oman
Keyword(s):  
Virtual Reality ◽  
Visual Processing ◽  
Line Length ◽  
Perceptual Cues ◽  
Virtual Reality Environment ◽  
Top Down ◽  
Test Conditions ◽  
The Subject ◽  
Processing Mechanisms

The role of top-down processing on the horizontal-vertical line length illusion was examined by means of an ambiguous room with dual visual verticals. In one of the test conditions, the subjects were cued to one of the two verticals and were instructed to cognitively reassign the apparent vertical to the cued orientation. When they have mentally adjusted their perception, two lines in a plus sign configuration appeared and the subjects had to evaluate which line was longer. The results showed that the line length appeared longer when it was aligned with the direction of the vertical currently perceived by the subject. This study provides a demonstration that top-down processing influences lower level visual processing mechanisms. In another test condition, the subjects had all perceptual cues available and the influence was even stronger.

Functional Anatomy of Intensity Aspects of Attention

2003 ◽  
Vol 14 (3) ◽  
pp. 181-190 ◽  
Author(s):  
Walter Sturm
Keyword(s):  
Right Hemisphere ◽  
Functional Anatomy ◽  
Fmri Data ◽  
Functional Networks ◽  
Top Down ◽  
Stimulus Modality ◽  
Spatial Orienting ◽  
Phasic Alertness ◽  
Co Activation ◽  
Attention System

Abstract: Behavioral and PET/fMRI-data are presented to delineate the functional networks subserving alertness, sustained attention, and vigilance as different aspects of attention intensity. The data suggest that a mostly right-hemisphere frontal, parietal, thalamic, and brainstem network plays an important role in the regulation of attention intensity, irrespective of stimulus modality. Under conditions of phasic alertness there is less right frontal activation reflecting a diminished need for top-down regulation with phasic extrinsic stimulation. Furthermore, a high overlap between the functional networks for alerting and spatial orienting of attention is demonstrated. These findings support the hypothesis of a co-activation of the posterior attention system involved in spatial orienting by the anterior alerting network. Possible implications of these findings for the therapy of neglect are proposed.

Auswirkungen eines Aufmerksamkeitstrainings auf die aphasische Symptomatik bei Schlaganfallpatienten

2011 ◽  
Vol 22 (1) ◽  
pp. 21-32 ◽  
Author(s):  
Julia Graf ◽  
Hartwig Kulke ◽  
Christa Sous-Kulke ◽  
Wilfried Schupp ◽  
Stefan Lautenbacher
Keyword(s):  
Top Down

Aufmerksamkeit kann als Kontrollsystem neuronaler Aktivität verstanden werden, welches Neuroplastizität top-down modulieren hilft. Bisher wurde selten versucht, durch deren gezielte Förderung Funktionswiederherstellungen nach Hirnschädigung zu begünstigen. In vorliegender Studie wurde dies am Beispiel der Aphasie erprobt. 15 Schlaganfallpatienten erhielten ein dreiwöchiges Training der selektiven Aufmerksamkeit mit den PC-Programmen CogniPlus und „Konzentration“ bei fünf Sitzungen pro Woche zusätzlich zur Standardtherapie, 13 weitere bildeten eine Kontrollgruppe ohne Aufmerksamkeitstraining. Zur Effektivitätskontrolle dienten zwei Versionen des Untertests Go/Nogo (Testbatterie zur Aufmerksamkeitsprüfung) und die Kurze Aphasieprüfung. Nach dem Training manifestierte sich zwischen den Untersuchungsgruppen kein Unterschied in Aufmerksamkeits- und Sprachfunktionen; das zusätzliche Aufmerksamkeitstraining war also wirkungslos. Allerdings zeigten Patienten mit deutlichen Aufmerksamkeitsverbesserungen tendenziell weniger Aphasie-Symptome, was die Hypothese aufmerksamkeitsvermittelter Plastizitätsmodulation nach Hirnschädigung partiell stützt.

Aufmerksamkeitswechsel und Konzentration: Von den Funktionen zum Mechanismus

2001 ◽  
Vol 209 (1) ◽  
pp. 34-53 ◽  
Author(s):  
Rainer Bösel
Keyword(s):  
Top Down ◽  
Eeg Alpha

Zusammenfassung. Aufmerksamkeit wird sowohl als Selektivität in der bewußter Verarbeitung oder auch als selektive neuronale Aktivierung verstanden. Die neuronalen Strukturen, die Objektdiskrimination ermöglichen, erlauben eine Interaktion von datengetriebenen und endogenen top-down Prozessen, die zu einer selektiven Bereitstellung von Verarbeitungs-Ressourcen führen. Zielgerichtetes Verhalten erfordert manchmal einen Wechsel in der Ressourcen-Bereitstellung und eine Konzentration von mentaler Aktivität. Aufmerksamkeitswechsel kann als ein zweiphasiger Prozeß verstanden werden, der aus einer breiten Mobilisierung von Gedächtnis-Ressourcen besteht (angezeigt durch EEG-Theta), gefolgt von einer re-organisierenden Einengung neuronaler Aktivität (angezeigt durch langsames EEG-Alpha). Dieser Beitrag unterstützt die Annahme, daß die Analyse des gekoppelten Wechselspiels aus Mobilisierung und Konzentration in bestimmten Teilen der posterioren und anterioren Rindenregionen ein Schlüssel für das Verständnis von Aufmerksamkeitswechsel sein könnte.

Psychology and Culture: Top Down Versus Bottom Up?

PsycCRITIQUES ◽  
2005 ◽  
Vol 50 (19) ◽  
Author(s):  
Michael Cole
Keyword(s):  
Top Down ◽  
Bottom Up
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