Diving of the sea snakePelamis platurus in the Gulf of Panamá

Fifteen yellow-bellied sea snakes,Pelamis platurus, fitted with pressure-sensitive ultrasonic transmitters, were tracked in the Gulf of Panamá during 1983–1985. Snakes spent up to 99.9% ( = 87%) of the tracking time under water and dived to 50 m. The maximum voluntary submergence time observed was 213 min, and of 202 complete dives logged, 19 exceeded 90 min. Dive durations of tracked snakes were typically longer than expected, based upon their estimated body-oxygen stores, and some were even longer than the reported survival times of forceably submerged snakes. Snakes, however, dived repeatedly and did not spend long periods at the surface between dives, suggesting that they did not develop an oxygen deficit during diving. Diving snakes may be able to avoid anaerobiosis by having a reduced metabolic rate, an enhanced rate of cutaneous oxygen uptake, or both. Surface conditions and subsurface temperatures influence the diving behavior ofP. platurus. Laboratory experiments in Panamá indicated that a larger number of snakes were submerged when surface water was turbulent. During February and March, the period of dry season upwelling in the Gulf of Panamá, sea snakes were found to avoid cooler, subsurface water and to make significantly shallower dives: mean maximum depth 6:8 m (n=76) in contrast to a mean maximum depth of 15.1 m (n=147) during the wet season. The dives during the dry season tended to be of shorter duration, with 44% lasting less than 15 min, compared to only 19% of the dives recorded during the wet season being completed in less than 15 min. General avoidance of subsurface temperatures cooler than 19°C was confirmed by laboratory experiments in the 10 m-deep tank at Scripps Institution of Oceanography.     

Effect of operational parameters on the removal of particulate chemical oxygen demand in the activated sludge process.

The removal of particulate material in the aeration basin of the activated sludge process is mainly attributed to bioflocculation and hydrolysis of particulate substrate. The bioflocculation process in the aeration tank of the activated sludge process occurs only under favorable conditions in the system, and several common operational parameters affect its performance. The principal objective of this research was to observe the effect of mixed liquor suspended solids, solids retention time (SRT), and extracellular polymer substances on the removal of particulate substrate by bioflocculation. A first-order particulate removal expression, based on flocculation, accurately described the removal rates for supernatant suspended solids and colloidal chemical oxygen demand. Based on the results presented in this investigation, a mixed liquor concentration of approximately 2200 mg/L, an SRT of at least 3 days, and a contact time of 30 minutes are needed for relatively complete removal of the particulate substrate in a plug-flow reactor.     

Ontogeny of feeding behavior and cranial morphology in the whitespotted bambooshark <Emphasis Type="Italic">Chiloscyllium plagiosum</Emphasis>

Morphological and behavioral development of the feeding apparatus over early ontogeny can profoundly affect the ability of an organism to obtain nourishment, ultimately impacting survival. The interplay between morphology and behavior over the first year of life was studied in the whitespotted bambooshark Chiloscyllium plagiosum (Bennett 1830) beginning in March of 2002 using high-speed videography and dissection. Externally measured variables describing cranial growth, and jaw weight, scaled at or near isometry while jaw and hyoid musculature, especially the coracohyoideus, demonstrated considerable hypertrophication. The difference between the volume of the buccal cavity when open and closed scaled with substantial positive allometry while the time to reach maximum jaw and hyoid abduction exhibited weak allometry, resulting in the capacity for more rapid and greater volumetric intake during feeding. In addition, the relative forward motion of the predator during a strike decreased over ontogeny and the feeding modality became more suction-dominated. Kinematic variables exhibited little variability and the primary aspect of food capture that was modulated in response to food type was the forward motion of the predator. An increase in capture success was noted for live, elusive shrimp over ontogeny indicating that morphological and behavioral changes have direct consequences for prey acquisition. Conservation of head shape coupled with a narrow behavioral repertoire is hypothesized to increase prey capture success in the wild over ontogeny as individuals become more proficient in the execution of a single, low-variability, suction-dominated capture behavior.     

Modelling Regression and Dispersion Parameters in a Complex Repeated Measures Experiment

We analyze data from a complex repeated measures experiment directed at the evaluation of the response to an electric stimulus applied to mussel nerves under 5 different salinity levels. We discuss the form of the relation between the response and the different salinity levels, as well as the choice of an adequate within subjects covariance structure that includes random effects and autoregressive models.     

Leonardo da Vinci’s “Last Supper”: a case study to evaluate the influence of visitors on the Museum preservation systems

Environmental Science and Pollution Research - The most important parameter to obtain an appropriate preservation condition of museum environments concerns the indoor air quality. The exposure of...     

New analytical approach to monitoring air quality in historical monuments through the isotopic ratio of CO2

Environmental Science and Pollution Research - In this study, we evaluated indoor air quality to highlight the effects of environmental pollution in the field of cultural heritage. In particular,...