Search

We report measurements of background gamma radiation levels on six islands in the northern Marshall Islands (Enewetak, Medren, and Runit onEnewetak Atoll; Bikini and Nam on Bikini Atoll; and Rongelap on Rongelap Atoll). Measurable excess radiation could be expected from the decay of 137Cs produced by the US nuclear testing program there from 1946 to 1958. These recordings are of relevance to safety of human habitation and resettlement. We find low levels of gamma radiation for the settled island of Enewetak [mean = 7.6 millirem/year (mrem/y) = 0.076 millisievert/year (mSv/y)], larger levels of gamma radiation for the island of Rongelap (mean = 19.8 mrem/y = 0.198 mSv/y), and relatively high gamma radiation on the island of Bikini (mean = 184 mrem/y = 1.84 mSv/y). Distributions of gamma radiation levels are provided, and hot spots are discussed. We provide interpolated maps for four islands (Enewetak, Medren, Bikini, and Rongelap), and make comparisons to control measurements performed on the island of Majuro in the southern Marshall Islands, measurements made in Central Park in New York City, and the standard agreed upon by the United States and the Republic of the Marshall Islands (RMI) governments (100 mrem/y = 1 mSv/y). External gamma radiation levels on Bikini Island significantly exceed this standard (P = <<0.01), and external gamma radiation levels on the other islands are below the standard. To determine conclusively whether these islands are safe for habitation, radiation exposure through additional pathways such as food ingestion must be considered. [ABSTRACT FROM AUTHOR]

Caution for the indiscriminate conversion of the isotopic niche into ecologic niche was recently advised. We tested the utility of the isotopic niche to answer ecological questions on oceanic islands. We compared the isotopic niches of black rats ( Rattus rattus) on two islands in the Gulf of California, Mexico: Farrallón de San Ignacio (FSI) and San Pedro Mártir (SPM). Both islands maintained several species of marine birds, but FSI is devoid of terrestrial vegetation and SPM has several species of terrestrial plants. We tested the hypothesis that rats on FSI have a narrower trophic niche due to its lower diversity of food items. We predicted a smaller variance in δC and δN values of rat muscle on FSI, and a lower use of marine birds as food on SPM. We also examined stomach contents of rats on both islands to validate the isotopic information. Variances in δC and δN values of black rats were lower on FSI, and the contribution of marine birds to the diet of rats was smaller on SPM. Stomachs in most rats collected on FSI contained only one or two types of food items, mostly marine birds and terrestrial invertebrates. In contrast, stomachs with only one type of food item were rare on SPM, and in most cases they contained three or more food types. Our findings showed that isotopic variance is a good approximation for trophic niche when comparing populations with access to an assemblage of preys with contrasting biological and isotopic diversity. [ABSTRACT FROM AUTHOR]

The ‘disappearing islands’ is a distinct idea that emerged out of the Intergovernmental Panel on Climate Change report to describe the vulnerability of small island states in the Pacific to sea-level rise as a result of climate change. In this article I deploy the ‘disappearing islands’ to map the complex politics of climate change governance. Through various governmental rationalities the ‘disappearing islands’ are operationalized as proof of climate catastrophe; as a means of concretizing climate science's statistical abstractions and as a signifier of the urgency and uneven impacts of global climate change. Drawing on focus group research from the Australian Research Council Linkage project Hot science, global citizens: The agency of the museum sector in climate change interventions, I juxtapose these multifarious governmental perspectives with the views of ordinary citizens in Australia and the United States in relation to the fate of the disappearing islands as a result of developed world consumption choices and carbon-burning practices. I conclude that rhetorical gestures made towards mobilizing a moral and ethical ecological citizenry charged with the responsibility of saving the ‘disappearing islands’ are too simplistic and more difficult to achieve than imagined. [ABSTRACT FROM PUBLISHER]

The HFire fire regime model was used to simulate the natural fire regime (prior to European settlement) on Kennedy Space Center, Merritt Island National Wildlife Refuge, Canaveral National Seashore, and Cape Canaveral Air Force Station, Florida. Model simulations were run for 500 years and the model was parameterized using information generated from previously published empirical studies on these properties (e.g., lightning fire ignition frequencies and ignition seasonality). A mosaic pattern of frequent small fires dominated this fire regime with rare but extremely large fires occurring during dry La Niña periods. This simulated fire size distribution very closely matched the previously published fire size distribution for lightning ignitions on these properties. A sensitivity analysis was performed to establish which parameters were most influential and the range of variation surrounding empirically parameterized model output. Dead fuel moisture and wind speed had the largest influence on model outcome. A wide range of variance was observed surrounding the composite simulation with the least being 6% in total burn frequency and the greatest being 49% in total area burned. Because simulation modeling is the best option for fire regime reconstruction in many rapidly growing shrub dominated systems, these results will be of interest to scientists and fire managers for delineating the natural fire regime on these properties, the southeastern United States and other fire adapted shrub systems worldwide. [Copyright &y& Elsevier]

Aim Mac Nally and Lake proposed a statistic ( η) for determining whether the diversity in archipelagos is better generated by several small patches (SS-dominance) or by a few large patches (SL-dominance). The η statistic improves the study of the generation of diversity in systems of patches, but the dependence of η on a particular species–area relationship may reduce its effectiveness. In this paper we show that η may be affected by the criterion used to distinguish between large and small patches. We propose alternative measures (ranked m-dominance indices) for the detection of SS/SL dominance, which separate the effects of each class of patch size on the generation of diversity. Location We use previously published species lists from three archipelagos: lizard species on 25 islands in the Gulf of California; non-introduced species of reptiles of the Canary Islands (order Squamata); and finch species from 19 islands of the West Indies. We also use one artificial data set. Methods Presence–absence data and the rank order of patch areas are used to define the m-dominance indices, interpreted as measures of preferential size of patches occupied by m species. A Monte Carlo procedure is implemented for testing the significance of the observed indices. Row and column totals in the simulated presence–absence matrices are kept fixed in order to maintain differences in species richness among sites and differences in occurrence frequencies among species, but the allocation of each occurrence to a specific ranked area is randomized. The analyses are exemplified with the three published data sets taken from the literature, and a hypothetical patch system neither SS- nor SL-dominated. Results The new m-dominance indices identified correctly the hypothetical patch system, while η was positive, suggesting an incorrect SL-dominant result. For the lizard data set, the standardized ranked m-dominance was significantly large for small m, confirming an SL-dominated system. Islands of varying size in the Canary archipelago hosted restricted reptile species, but matrix sparseness seems to have caused the non-significant results for the m-dominance indices in this case. The overall pattern of the West Indies system shows that medium-large islands are dominant, but most Monte Carlo analyses were not significant, also possibly as a result of matrix sparseness. Main conclusions The m-dominance indices have the virtue of summarizing composition–area relationships, and including Monte Carlo procedures for testing whether patch size and the type of species distribution (species restricted to m patches, m = 1,..., s) are random or not . When m is as low as 1 or 2, the m-dominance indices may typify the role of restricted species on the generation of diversity in the system of patches. The procedure developed here can be generalized to include other ordinal properties of patches, such as isolation or habitat heterogeneity. [ABSTRACT FROM AUTHOR]

Focuses on a study which examined the food habits of white-tailed deer in the wet prairie-tree island habitat of the southwestern Everglades system during 1988 to 1991. Description of the study area; Methods; Discussion and findings.

Investigates the influence of exotic species on native predators in California. Level of fox and skunk capture; Decline of fox population in the presence of skunks; Contribution of disease to carnivore abundance.

A core from Prince of Wales Island in the central Canadian Arctic was analysed for pollen and sediment characteristics. From 9200 yr BP to 7000 yr BP, the landscape supported a pioneer vegetation under cold conditions, with relatively high sediment input to the lake. Between 7000 and 4000 yr BP there was a period of high pollen concentrations, more abundant Cyperaceae and Dryas on the landscape and finer sediment input. In the last 4000 years, climate cooling is indicated. [ABSTRACT FROM AUTHOR]

Discusses Hawaii and the Galápagos Islands, which are two island ecosystems that are thought to be a significant and unique part of earth's biota. Characteristics of the two archipelagos, which are both of volcanic origin and are roughly similar in size; Observation that while Hawaii has only a single native terrestrial mammal, a bat, the Galápagos Islands have native rodents and reptiles; Damage which has been done to the vegetation of both archipelagoes from the grazing of feral goats; The impact of non-native black rats on the tortoise and dark-rumped petrel populations of the Galápagos; The problem of avian disease in Hawaii and the Galápagos; Outlook for the future management of island species invasions.

Determines if plants with nitrogen-fixing symbioses have an impact on nutrient availability and community succession in coastal heathland ecosystems on Nantucket Island in Massachusetts. Testing methodology; Comparison of plants with N-fixing symbionts to soils associated with other plants; Results; Nitrogen availability was no different in soils collected beneath N-fixing species than in soils collected away from N-fixing species; Discussion to study.