Environmental variabilities and the distribution of octocorals and black corals in Hong Kong

A recent comprehensive survey covering 125 sites in Hong Kong waters recorded 29 soft coral species in 14 genera, 38 species of gorgonians in 19 genera and six species of black corals in two genera. Environmental variabilities based on water quality data collected by Hong Kong Environmental Protection Department were analyzed using multivariate statistics to find variables that are significantly correlated with coral distribution patterns. Eleven water quality zones with similar environmental variabilities were recognized, which could further be classified into five groups, namely Inner Bay, Outer Bay, Eastern, Western and Southern waters. LINKTREE analysis provided an overall trend indicating the importance of salinity, sediment and nutrient loadings in affecting octocoral and black coral distribution from west to east of Hong Kong waters, and from inner to outer bays. Furthermore, water turbidity and wave exposure could also affect the coral distribution patterns from north, northeast to southern waters.     

Energy dependence of Ti/Fe ratio in the Galactic cosmic rays measured by the ATIC-2 experiment

Titanium is a rare, secondary nucleus among Galactic cosmic rays. Using the Silicon matrix in the ATIC experiment, Titanium has been separated. The energy dependence of the Ti to Fe flux ratio in the energy region from 5 GeV per nucleon to about 500 GeV per nucleon is presented. The article was translated by the authors.     

Potential climate change effects on warm-season livestock production in the Great Plains

Projected production responses were derived for confined swine and beef and for milk-producing dairy cattle based on climate change projections in daily ambient temperature. Milk production from dairy cattle and the number of days to grow swine and beef cattle were simulated. Values were obtained for three central United States transects and three climate scenarios which were based on projected mean daily ambient temperatures associated with a baseline, doubling, and tripling of atmospheric greenhouse gas (CO₂) levels for the period June 1 to October 31. For swine, a slight northwest to southeast gradient is evident. Transect 1 (west side) shows no losses under the doubling scenario and losses up to 22.4% under the tripling scenario. Transect 3 (east side) displays losses of over 70% under the tripling scenario. For beef, positive benefits were simulated in Transect 1 with increasing temperatures, although a northwest to southeast gradient was also evident. For dairy, no positive benefits in milk production were found due to climate effects. Projected production declines ranged from 1% to 7.2%, depending on location. However, ranges in predicted differences were less than those simulated for beef and swine. These simulations suggest regional differences in animal production due to climate change will be apparent. For small changes in climate conditions, animals will likely be able to adapt, while larger changes in climate conditions will likely dictate that management strategies be implemented. Exploration of the effects of climate changes on livestock should allow producers to adjust management strategies to reduce potential impact and economic losses due to environmental changes.     

The effects of land tenure on vulnerability to droughts in Northeastern Brazil

This article presents evidence on two distinct farming systems—one that utilizes common property pasturelands and another based on private pasturelands—in the Brazilian semi-arid zone. The research is based on a survey carried out in the state of Bahia in 2002. A bivariate analysis was carried out to compare agricultural outputs and income generated in each system. Data suggest that there are no significant differences between the two groups concerning income generation. However, farmers using common pasturelands have more diversified systems and invest more on small-animal husbandry, which are adapted to the dry environment. As a consequence, families that use common pasturelands have a higher consumption of animal protein. These families are thus not necessarily more vulnerable to droughts than those with private pasturelands. Formulating effective institutions to control access to the commons is a strategy pursued by some communities, yet, their ecological sustainability is still unknown.     

Book Review

Electronic Surveying and Navigation by Simon H. Laurila (New York: John Wiley &; Sons, 1976), 545 pages, hardcover, $25.00.     

Characterization of marine aggregates off Waikiki,O'ahu,Hawai'i

Researchers at the University of Hawai'i at Manoa have been working for the past several years to develop the necessary techniques for finding and quantitatively characterizing offshore unconsolidated carbonate deposits with potential for beach nourishment and use in construction aggregates for tropical island communities. This article examines particular results of this research, with special attention given to the area offshore from Waikiki Beach. Acoustic surveying, water‐jet probing to measure the thickness of unconsolidated material and three different sampling methods were used in this study. Two separate seismic systems were used for the subbottom profiling survey, a Datasonics Bubble‐Pulser® system and a broad‐band, frequency‐modulated ("chirp") prototype system.

The following conclusions were reached. (1) Many different types of sediment underlie tropical island carbonate sand deposits and serve as refusing horizons to jet probing. Examples include consolidated or unconsolidated reef debris, beach rock, cemented sand, and various types of conglomerates formed from rhodoliths (coralline algae) or reef detritus. (2) Massive coral growth over clastic deposits is not a common offshore feature in this area, though it does occur in some areas off the Reef Runway. (3) Matrices of the coral Porites compressa, in‐filled with sand, may have acoustic properties similar to those of the sand bodies. Such deposits may be difficult to distinguish from unconsolidated deposits from seismic records alone. (4) Significant new prospects for offshore aggregates were found in the insular shelf offshore from Southern O'ahu. A total of 5,100,000 m³ were mapped off Waikiki. The Makua Shelf deposits in this area presently appear to be the best prospects for commercial development.     

Improving vertical GPS precision with a GPS-over-fiber architecture and real-time relative delay calibration

A limitation of GPS positioning is that the vertical component is generally two to three times less precise than the horizontal components. In a previous work by R. Santerre of Laval University and G. Beutler of University of Bern, it was shown in simulations that it is possible to improve the GPS vertical positioning precision by using a multi-antenna GPS receiver and a precise calibration technique of the relative hardware delay between the antennas and the receiver. However, no actual implementation of the system was done to prove the concept until now. A new multi-antenna, GPS-over-fiber architecture with real-time delay monitoring, designed and implemented to improve the vertical precision is presented. The improvement in vertical precision arises from the elimination of the relative receiver clock error in single difference, between antennas, and the precision real-time calibration of the relative hardware delay. Experiments were conducted with a zero baseline and a short baseline configuration. The results show, as expected by the theory and the simulations, a two to three times improvement in the precision of the vertical component such that it reached the same level of performance as the horizontal components. These promising results will enable the use of this type of configuration in several applications where the same precision in all 3D components is essential and could not be achieved before with standard GPS positioning techniques.     

Origins and antiquity of the island fox (Urocyon littoralis) on California's Channel Islands

The island fox (Urocyon littoralis) is one of few reportedly endemic terrestrial mammals on California's Channel Islands. Questions remain about how and when foxes first colonized the islands, with researchers speculating on a natural, human-assisted, or combined dispersal during the late Pleistocene and/or Holocene. A natural dispersal of foxes to the northern Channel Islands has been supported by reports of a few fox bones from late Pleistocene paleontological localities. Direct AMS ¹⁴C dating of these “fossil” fox bones produced dates ranging from ∼ 6400 to 200 cal yr BP, however, postdating human colonization of the islands by several millennia. Although one of these specimens is the earliest securely dated fox from the islands, these new data support the hypothesis that Native Americans introduced foxes to all the Channel Islands in the early to middle Holocene. However, a natural dispersal for the original island colonization cannot be ruled out until further paleontological, archaeological, and genetic studies (especially aDNA [ancient DNA]) are conducted.     

Ion exchange and trace element surface complexation reactions associated with applied recharge of low-TDS water in the San Joaquin Valley,California

Stable isotope data, a dissolved gas tracer study, groundwater age dating, and geochemical modeling were used to identify and characterize the effects of introducing low-TDS recharge water in a shallow aerobic aquifer affected by a managed aquifer recharge project in California’s San Joaquin Valley. The data all consistently point to a substantial degree of mixing of recharge water from surface ponds with ambient groundwater in a number of nearby wells screened at depths above 60 m below ground surface. Groundwater age data indicate that the wells near the recharge ponds sample recently recharged water, as delineated by stable O and C isotope data as well as total dissolved solids, in addition to much older groundwater in various mixing proportions. Where the recharge water signature is present, the specific geochemical interactions between the recharge water and the aquifer material appear to include ion exchange reactions (comparative enrichment of affected groundwater with Na and K at the expense of Ca and Mg) and the desorption of oxyanion-forming trace elements (As, V, and Mo), possibly in response to the elevated pH of the recharge water.