scholarly journals Role of daily light period in the depth distribution of Zostera marina (eelgrass)

1985 ◽  
Vol 25 ◽  
pp. 51-61 ◽  
Author(s):  
WC Dennison ◽  
RS Alberte
Keyword(s):  
Zostera Marina ◽  
Depth Distribution ◽  
Light Period

scholarly journals Disruption of essential habitat by a coastal invader: new evidence of the effects of green crabs on eelgrass beds

2011 ◽  
Vol 68 (9) ◽  
pp. 1852-1856 ◽  
Author(s):  
Andrey Malyshev ◽  
Pedro A. Quijón
Keyword(s):  
Invasive Species ◽  
Zostera Marina ◽  
Laboratory Experiments ◽  
Carcinus Maenas ◽  
Green Crab ◽  
Atlantic Canada ◽  
Marine Science ◽  
Eelgrass Beds ◽  
New Evidence

Abstract Malyshev, A., and Quijón, P. A. 2011. Disruption of essential habitat by a coastal invader: new evidence of the effects of green crabs on eelgrass beds. – ICES Journal of Marine Science, 68: 1852–1856. Eelgrass (Zostera marina) beds have been declining in Atlantic Canada and elsewhere, partly as a result of sediment disruption and direct feeding/cutting of basal meristems by the green crab (Carcinus maenas). Green crabs are detrimental to eelgrass beds, and field and laboratory experiments have confirmed that the deleterious role of this invasive species is mediated by at least two mechanisms, depending on the size/age of the crabs: uprooting by adults and grazing by juveniles. Eelgrass uprooting and grazing by green crabs are likely to contribute to further declines or a lack of recovery of eelgrass beds.

scholarly journals 125 THE ROLE OF ETHYLENE IN THE DEVELOPMENT OF CONSTANT-LIGHT INJURY OF POTATO

HortScience ◽  
1994 ◽  
Vol 29 (5) ◽  
pp. 446c-446
Author(s):  
K. E. Cushman ◽  
T. W. Tibbitts
Keyword(s):  
Solanum Tuberosum ◽  
Leaf Tissue ◽  
Dry Weight ◽  
Light Period ◽  
Constant Light ◽  
Silver Thiosulfate ◽  
Ethylene Action ◽  
Teflon Film ◽  
Necrotic Spotting

Chlorosis and necrotic spotting develop on expanding leaves of particular cultivars of potato (Solanum tuberosum L.) when grown under constant light and temperature conditions. Plantlets of a constant-light sensitive cultivar, Kennebec, were planted into peat:vermiculite and established at 18C for 10 d under a 12 h light: 12 h dark photoperiod. Plants were then exposed to constant light and sprayed with 1 ml of either 0.5 mM silver thiosulfate (STS), an ethylene-action inhibitor, or water (as a control) every 2 days. Specific `target' leaflets, 5-10 mm in length at the beginning of the constant-light period, were harvested on days 5-9 of constant light, during injury development, and placed in bags made of Teflon film for IO-15 minutes to collect ethylene. Ethylene release and necrotic spotting increased as days of constant light increased for both water and STS-treated leaves, though STS-treated leaves produced slightly less ethylene and significantly less necrotic spotting than water-treated leaves. Ethylene release was correlated with extent of necrotic spotting. STS-treated plants exhibited greater dry weight and leaf area then water-treated plants. The results indicate that ethylene is not only produced by injured leaf tissue but, in addition, that ethylene may have a role in the development of constant-light injury symptoms.

scholarly journals Feedback contribution to surface motion perception in the human early visual cortex

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Ingo Marquardt ◽  
Peter De Weerd ◽  
Marian Schneider ◽  
Omer Faruk Gulban ◽  
Dimo Ivanov ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Motion Perception ◽  
Depth Distribution ◽  
Ultra High Field ◽  
Surface Perception ◽  
Surface Motion ◽  
Surface Segmentation ◽  
Early Visual Cortex ◽  
Illusory Perception

Human visual surface perception has neural correlates in early visual cortex, but the role of feedback during surface segmentation in human early visual cortex remains unknown. Feedback projections preferentially enter superficial and deep anatomical layers, which provides a hypothesis for the cortical depth distribution of fMRI activity related to feedback. Using ultra-high field fMRI, we report a depth distribution of activation in line with feedback during the (illusory) perception of surface motion. Our results fit with a signal re-entering in superficial depths of V1, followed by a feedforward sweep of the re-entered information through V2 and V3. The magnitude and sign of the BOLD response strongly depended on the presence of texture in the background, and was additionally modulated by the presence of illusory motion perception compatible with feedback. In summary, the present study demonstrates the potential of depth-resolved fMRI in tackling biomechanical questions on perception.

Mediation functions in Ecopath with Ecosim: handle with care

2014 ◽  
Vol 71 (7) ◽  
pp. 1020-1029 ◽  
Author(s):  
Chris J. Harvey
Keyword(s):  
Zostera Marina ◽  
Pacific Salmon ◽  
Initial Conditions ◽  
Experimental Studies ◽  
Ecopath With Ecosim ◽  
Ecosystem Models ◽  
Ecological Processes ◽  
Juvenile Pacific Salmon ◽  
Initial States

Ecosystem models are important tools for addressing complex issues such as the role of habitat in marine resource management. The Ecopath with Ecosim (EwE) software can represent several ecological processes via mediation functions, where the abundance of one group influences trophic interactions between two other groups. I ran a series of temporal simulations in EwE, in which eelgrass (Zostera marina) was refuge habitat for juvenile Pacific salmon (Oncorhynchus spp.), and the abundance of eelgrass mediated (reduced) the vulnerability of juvenile salmon to their predators. I compared the effects of eelgrass on salmon biomass across three shapes of mediation curve (linear, hyperbolic, sigmoid) and six different initial states along each curve. Salmon responded strongest to sigmoid mediation and least to hyperbolic mediation. Salmon responses were sensitive to initial conditions, particularly along sigmoid curves. As the lower limit of the mediation curve (Mmin) approached 0, model results became nonintuitive, particularly for sigmoid curves. Because these functions are difficult to quantify or scale from empirical or experimental studies, modelers must carefully account for uncertainty when using mediation relationships in EwE. Hyperbolic mediation curves may be the most conservative when empirical or theoretical knowledge is unavailable.

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