Trace element geochemistry of soils and plants in Kenyan conservation areas and implications for wildlife nutrition

Trace element concentrations in soils, plants and animals in National Parks and Wildlife Reserves in Kenya are assessed using geochemical mapping techniques. Soil trace element concentrations are shown to be related to soil parent material and possibly to pedological and hydrological factors. At Lake Nakuru National Park, plant trace element concentrations vary with plant species and the geochemical conditions that influence uptake are discussed. Impala at Lake Nakuru National Park and black rhino at Solio Wildlife Reserve are shown to have a lower blood copper status than animals from other areas. The trace element status of wildlife is assessed also with respect to critical concentrations used for domestic ruminants. It is suggested that at Lake Nakuru National Park, the low soil copper content and high molybdenum content of some plants contributes to the low copper status of impala and may also influence the nutrition of other species.     

Defensive behavior of ants in a mutualistic relationship with aphids

Mutualistic relationships between ants and aphids are well studied but it is unknown if aphid-attending ants place a greater relative importance on defending aphids from aphid-predators or from competing ant colonies. We tested the hypothesis that aphid-attending ants defend their aphids against aphid-predators more aggressively than against ants from neighboring colonies. We conducted introduction trials by placing an individual non-predatory insect, an aphid-predator, or a foreign conspecific ant on the leaf of a resident ant. We found that ants did not attack non-predatory insects, but did attack competing ants and aphid-predators. When we presented resident ants with both the threats (i.e., predator and competitor) at the same time, residents always attacked potential competitors as opposed to aphid-predators. We suggest this behavior may reduce the likelihood of raids by neighboring colonies. Ants appear to balance both the energetic costs of making an attack and the costs associated with losing aphids to a predator, against the benefits of signaling their defensive ability to rivals and/or preventing rivals from gaining knowledge of a potential food resource.     

Utilization of nitrogen derived from seabird guano by terrestrial and marine plants at St. Paul, Pribilof Islands, Bering Sea, Alaska

Dense, conspicuous colonies of seabirds and pinnipeds breed on ocean islands throughout the world. Such colonies have been shown to have local impacts on prey populations, but whether or not they affect nutrient cycling has been debated. We determined the natural abundance levels of the stable isotopes (C and N) of primary producers, seabirds and other consumers at and near St. Paul Island, Pribilof Islands, Bering Sea, in summer 1993. Marine primary producers (phytoplankton, as particulate organic matter, and kelp) collected near seabird colonies were ca. 6.5‰ enriched in both ¹⁵N and ¹³C relative to those collected further from shore. Terrestrial plants collected near the seabird colonies were enriched in ¹⁵N (δ¹⁵N ca. 22‰) compared with conspecifics collected away from the colonies (δ¹⁵N ca. 11‰). The trend towards higher δ¹⁵N values in marine and terrestrial plants near bird colonies is consistent with their uptake of ornithogenic N. This ¹⁵N-enrichment of plants using ornithogenic N can be attributed to a combination of two processes: trophic enrichment, and volatilization of ammonia produced during degradation of terrestrially deposited guano. Seabird breeding colonies at St. Paul Island appear to be significant sources of recycled nitrogen for terrestrial plants in the vicinity of colonies and for phytoplankton in the nearshore zone. Received: 4 July 1997 / Accepted: 20 November 1997     

Procedure for the determination of 2,4‐D and dicamba in inhalation,dermal, hand‐wash,and urine samples from spray applicators

Abstract

Analytical procedures for the simultaneous determination of residues of 2,4‐D and dicamba from polyurethane foam plug air samplers, ethylene glycol impregnated glass‐fiber filter paper dermal samplers, 1% sodium bicarbonate hand wash solution, and urine are presented. Residues were derivatized with diazomethane and quantitated using electron capture gas chromatography. Recoveries were greater than 80% at the limit of detection in all substrates. The limits of detection for both herbicides were 0.1 μg/foam plug and 0.5 μg/filter paper, and in the urine, 1.7 μg/100 mL and 5.0 μg/100 mL for dicamba and 2,4‐D, respectively.     

Characterizing Interpersonal Influence for Grassland Conservation Behaviours in a Unique Population

Interpersonal communication can influence the decisions people make about engaging in conservation behaviours. In-depth interviews with Tibetan pastoralists serve as the basis for examining interpersonal communication patterns and sources of interpersonal influence about grassland conservation behaviours. Herding and family groups are key collectives; salient sources of information vary across types of information. Salient individuals are those with credibility and means control: community leaders, elders, veterinarians, and government officials. Explicit information about conservation comes from religious leaders. The findings have significant implications for understanding the function and nature of interpersonal influence in unique population groups regarding conservation actions.     

Residues of 2,4‐D in air samples from Saskatchewan: 1966–1975

Abstract

Residues of 2,4‐D (2,4‐dichlorophenoxyacetic acid) in air samples from several sampling sites in central and southern Saskatchewan during the spraying seasons in the 1966–68 and 1970–75 periods were determined by gas‐liquid Chromatographic techniques. Initially, individual esters of 2,4‐D were characterized by retention times and confirmed further by co‐injection and dual column procedures. Since 1973, however, only total 2,4‐D acid levels in air samples have been determined after esterification to the methyl ester and confirmed by gc/ms techniques whenever possible.

Up to 50% of the daily samples collected during the spraying season at any of the locations and during any given year contained 2,4‐D, with butyl esters being found most frequently. The daily 24‐hr mean atmospheric concentrations of 2,4‐D ranged from 0.01 to 1.22 μg/m³, 0.01 to 13.50 μg/m³, and 0.05 to 0.59 μg/m for the iso‐propyl, mixed butyl and iso‐octyl esters, respectively. Even when the samples were analysed for the total 2,4‐D content, i.e. from 1973 onwards, the maximum level of the total acid reached only 23.14 μg/m. In any given year and at any of the sampling sites, about 30% of the samples contained less than 0.01 μg/m³ of 2,4‐D. In another 40% of the samples, the levels of 2,4‐D ranged from 0.01 to 0.099 yg/m. Only about 30% of the samples contained 2,4‐D concentrations higher than 0.1 μg/m³, with only 10% or less exceeding 1 μg/m³.

None of the samples, obtained with the high volume particu‐late sampler, showed any detectable levels of 2,4‐D, indicating little or no transport of 2,4‐D adsorbed on dust particles or as crystals of amine salts.     

Eco-restoration: Simultaneous nutrient removal from soil and water in a complex residential-cropland area

An eco-restoration system to remove excess nutrients and restore the agricultural ecosystem balance was proposed and applied from August 2006 to August 2008 in a residential-cropland complex area (1.4 × 10⁵ m²) in Kunming, western China, where the self-purifying capacity of the agricultural ecosystem had been lost. The proposed eco-restoration system examined includes three main foci: farming management, bioremediation, and wastewater treatment. The results showed that the removal efficiencies of total phosphorus (TP) and total nitrogen (TN) from the complex wastewater were 83% and 88%, respectively. The Simpson’s diversity indices of macrophytes and zoobenthos indicated that the system had increased macrophyte and zoobenthic diversity as well as improved growth conditions of the plankton habitats. The results demonstrated that the proposed eco-restoration system is a promising approach for decreasing the output of nutrients from soil, improving agricultural ecosystem health, and minimizing the downstream eutrophication risk for surface waters.