scholarly journals The diurnal aggregation behavior in Phasmahyla cochranae tadpoles (Anura: Hylidae)

Author(s):  
Thiago Augusto Leão-Pires ◽  
Ariovaldo Giaretta ◽  
Ricardo Jannini Sawaya

We investigated schooling behavior of Phasmahyla cochranae including its periodicity based on periodic regression models. The school structure and differences between day and night were discussed. We found that tadpoles formed aggregative schools, which were significantly more frequent during the day than at night. During the day, from 06:30 to 18:00 h, tadpoles formed one or two polarized schools at the water surface. Based on these results and on observations of specific behaviors, we suggest that daylight may be a significant environmental factor related to schooling behavior in P. cochranae, although this hypothesis needs to be further investigated.

2012 ◽  
Vol 371 (1) ◽  
pp. 52-61 ◽  
Author(s):  
Nandhibatla V. Sastry ◽  
Nilesh M. Vaghela ◽  
Pradip M. Macwan ◽  
Saurabh S. Soni ◽  
Vinod K. Aswal ◽  
...  

2007 ◽  
Vol 5 (1) ◽  
pp. 81-83 ◽  
Author(s):  
Carolina Delgado de Carvalho ◽  
Carolina Marocco Corneta ◽  
Virginia Sanches Uieda

Schools of mullets, Mugilidae, are abundant in estuaries and shallow marine waters. We report on the schooling behavior of juvenile white mullet, Mugil curema, in the estuary of the Canto da Paciência stream, in Ubatuba, southeastern Brazil. Schools of small fish (15 to 35 mm TL) were composed of a larger number of individuals (up to a hundred individuals), and were found feeding mainly in shallow nearshore waters, whereas schools of larger fish (40 to 100 mm TL) were observed only in deeper waters. Three patterns of swimming were observed for the schools: stationary feeding, slow movement while searching for food, and rapid displacement. The variations observed in school structure and behavior seem to be related to the balance between predation risk and increasing food intake.


2009 ◽  
Vol 45 (9) ◽  
pp. 2540-2548 ◽  
Author(s):  
Houjian Gong ◽  
Guiying Xu ◽  
Hui Ding ◽  
Xiaofeng Shi ◽  
Yebang Tan

2014 ◽  
Vol 2014 (1) ◽  
pp. 300108
Author(s):  
Deborah French McCay ◽  
Danielle Reich ◽  
Jacqueline Michel ◽  
Dagmar Etkin ◽  
Lisa Symons ◽  
...  

An evaluation was made of the amounts and types of oil potentially released from sunken vessels in U.S. waters, where oil would be transported, how rapidly it would reach sensitive resources, and magnitudes of impacts on surface water and shorelines. Oil spill modeling was performed as part of a screening analysis to identify those sunken vessels of highest risk for environmental and socioeconomic impacts, with the expectation that those identified will be subject to more detailed analysis. The modeling provides estimates of the locations of oiling, as well as areas of water surface, lengths of shoreline, and volumes of water exposed above potential effects thresholds (oil thickness or concentrations). We developed regression models of the resulting indices of oil impacts as a function of spill volume, allowing for predictions of water surface area, shoreline extent, and water volume affected for any potential (partial or entire) release volume from the sunken vessel. We ran RPS-ASA's SIMAP model in probabilistic mode, i.e., long-term wind and current records were sampled at random and model runs performed for each of 200 selected spill dates and times. The model results provide a statistical description of the probabilities and potential locations and magnitudes of oil-related impacts. This consequence analysis may be used to assign priorities for potential salvage of sunken vessels based on relative risk. The resultant analysis may be used by decision-makers to evaluate response needs, such as response equipment capacities, timing of deployment required to protect sensitive resources, and possible time windows and areas for dispersant use.


Author(s):  
K. T. Tokuyasu

During the past investigations of immunoferritin localization of intracellular antigens in ultrathin frozen sections, we found that the degree of negative staining required to delineate u1trastructural details was often too dense for the recognition of ferritin particles. The quality of positive staining of ultrathin frozen sections, on the other hand, has generally been far inferior to that attainable in conventional plastic embedded sections, particularly in the definition of membranes. As we discussed before, a main cause of this difficulty seemed to be the vulnerability of frozen sections to the damaging effects of air-water surface tension at the time of drying of the sections.Indeed, we found that the quality of positive staining is greatly improved when positively stained frozen sections are protected against the effects of surface tension by embedding them in thin layers of mechanically stable materials at the time of drying (unpublished).


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