Moderate-depth benthic habitats of St. John, U.S. Virgin Islands

The National Oceanic and Atmospheric Administration’s (NOAA) Center for Coastal Monitoring and Assessment’s (CCMA) Biogeography Branch and the U.S. National Park Service (NPS) have completed mapping the moderate-depth marine environment south of St. John. This work is an expansion of ongoing mapping and monitoring efforts conducted by NOAA and NPS in the U.S. Caribbean. The standardized protocols used in this effort will enable scientists and managers to quantitatively compare moderate-depth coral reef ecosystems around St. John to those throughout the U.S. Territories. These protocols and products will also help support the effective management and conservation of the marine resources within the National Park system.

Swimming depth, ambient water temperature preference, and feeding frequency of young Pacific bluefin tuna (Thunnus orientalis) determined with archival tags

We investigated the migration and behavior of young Pacific Bluefin tuna (Thunnus orientalis) using archival tags. The archival tag measures environmental variables, records them in its memory, and estimates daily geographical locations based on measured light levels. Of 166 archival tags implanted in Pacific bluefin tuna that were released at the northeastern end of the East China Sea from 1995 to 1997, 30 tags were recovered, including one from a fish that migrated across the Pacific. This article describes swimming depth, ambient water temperature, and feeding frequency of young Pacific bluefin tuna based on retrieved data. Tag performance, effect of the tag on the fish, and horizontal movements of the species are described in another paper. Young Pacific bluefin tuna swim mainly in the mixed layer, usually near the sea surface, and swim in deeper water in daytime than at nighttime. They also exhibit a pattern of depth changes, corresponding to sunrise and sunset, apparently to avoid a specific low light level. The archival tags recorded temperature changes in viscera that appear to be caused by feeding, and those changes indicate that young Pacific bluefin tuna commonly feed at dawn and in the daytime, but rarely at dusk or at night. Water temperature restricts their distribution, as indicated by changes in their vertical distribution with the seasonal change in depth of the thermocline and by the fact that their horizontal distribution is in most cases confined to water in the temperature range of 14−20°C.

Snow depth as an indicator of weather and climate in the Sierra Nevada

EXTRACT (SEE PDF FOR FULL ABSTRACT): The purpose of this study is to determine: (1) whether the cooperative station snow depth contains useful weather and climate information, (2) how cooperative snow depth variability is related to snowcourse variability, and (3) how it is related to other weather elements. From an examination of stations in the Sierra Nevada of California, it is clear that cooperative snow records and snowcourse records have consistent spatial and temporal variability. ... We show that high snow ratio (low density snow or high SD/Ppt) events have low temperatures and high amplitude atmospheric circulation patterns over the eastern North Pacific. In contrast, low snow ratio (high density or low SD/Ppt) events have warm temperatures and a zonal flow pattern with a southerly displaced storm track from Hawaii to the West Coast.

On the operation of small shrimp trawls in shallow waters-scope-ratio and size-depth relation

Studies on small trawls seem to be comparatively less. These trawls are generally operated in shallower waters, where due to the limitations in the length of warp that could be released, size restrictions have to be considered for their efficient functioning. An attempt has been made to assess the effective scope-ratio of length of warp required for the operation of trawls at shallower depth and to a judge the size of trawl suitable for use at lower depths.

Seasonal variation of mixed layer depth in the north Arabian Sea

The Arabian Sea is unique due to the extremes in atmospheric forcing that lead to the semi-annual seasonal changes. The reversing winds of summer and winter monsoon induce the variation in the characteristics of mixed layer depth. The importance of mixed layer depth is recognized in studying the biological productivity in the ocean. In this paper variability of mixed layer depth in the north Arabian Sea have been discussed. The study is based on the data collected under North Arabian Sea Environment and Ecosystem Research (NASEER) program. The results of the study indicate that there is a significant variation in the mixed layer depth from summer to winter monsoon as well as coast to offshore.

Belly depth studies for shrimp trawls - Part II

The paper details further experiments conducted for a reduction in the depth of belly of a 13.69 m (45') four seam shrimp trawl net. The investigations have given conclusive evidence that the optimum depth of belly for this particular trawl design should be 70 meshes.

Paper re-use: Toner-print removal by laser ablation

This article explores the possibility of using a laser to remove toner-print from office paper. Removal of print would allow paper to be re-used instead of being recycled or disposed into a landfill. This might reduce climate change gas emissions per tonne of office paper by between 45% and 95%. Although there is little previous research on the area, a number of related articles on paper conservation methods using laser radiation can be found in literature. Different authors have studied the effects of laser energy on blank paper and its application for cleaning soiled paper. However, this study examines toner-print removal from paper by laser ablation. In this article a laser in the visible range is applied to a single toner-paper combination with a range of energy fluences. Results are evaluated by means of colour measurements under the L*a*b* colour space and SEM images. Analysis of the samples reveals that there are parameters under which it is possible to remove toner from paper without causing significant discolouration or damage to the substrate. This means that it is technically possible to remove toner-print for paper re-use.