Polychlorinated biphenyls in the Brisbane River estuary, Australia

The concentrations of PCBs in water, sediments, fish (6 species), crustacea (3 species), molluscs (1 species), polychaetes (mixed species) and birds (1 species) from the Brisbane River estuary were determined. Levels were comparable to other similar situations elsewhere. No relationship was found between trophic class and PCB concentration although pelicans at the highest trophic level examined exhibited the highest muscle tissue concentration (i.e., 15.7 mg kg⁻¹ on a wet weight basis). The pattern of distribution of PCBs within body tissues of fish was closely related to lipid content.     

Response of juvenile lemon sharks, Negaprion brevirostris, to a magnetic barrier simulating a beach net

Beach nets are preventative devices used to minimize interactions between potentially harmful sharks and unsuspecting swimmers. Quantitative studies demonstrated that beach nets drastically reduced local elasmobranch populations, as well as caused considerable bycatch mortality. For this experiment, a beach net-like device was constructed and the behaviors of six juvenile lemon sharks (Negaprion brevirostris) were analyzed. Induced by olfactory and gustatory cues, sharks were given the choice to swim through a magnetic or control opening in the net. In the first trial, all six sharks avoided the magnetic region and significantly preferred to swim through the control region of the fence. The magnetic stimulus no longer affected the swimming behavior of three sharks retested after resting 24 h. Results from the retested sharks were correlated with those from repeated tonic immobility trials, which demonstrated a linear decrease in sensitivity to repeated magnetic stimulation. This study serves as a baseline experiment demonstrating that permanent magnets may substantially decrease elasmobranch mortality within beach nets.     

High-Resolution Records of the Holocene Paleoenvironmental Variation Reflected by Carbonate and Its Isotopic Compositions in Bosten Lake and Response to Glacial Activities

Abstract: The Early Holocene paleoclimate in Bosten Lake on the northern margin of the Tarim Basin, southern Xinjiang, is reconstructed through an analysis of a 953 cm long core (BSTC2000) taken from Bosten Lake. Multiple proxies of this core, including the mineral components of carbonate, carbonate content, stable isotopic compositions of carbonate, Ca/Sr, TOC and C/N and C/S of organic matter, are used to reconstruct the climatic change since 8500 a B.P. The chronology model is made by nine AMS 14C ages of leaves, seeds and organic matter contained in two parallel cores. The climate was cold and wet during 8500 to 8100 a B.P. Temperature increased from 8100 to 6400 a B.P., the climate was warm and humid, and the lake expanded. The lake level was highest during this stage. Then from 6400 to 5100 a B.P., the climate became cold and the lake level decreased slightly. During the late mid-Holocene, the climate was hot and dry from 5100 to 3100 a B.P., but there was a short cold period during 4400 to 3800 a B.P. At this temporal interval, a mass of ice and snow melting water supplied the lake at the early time and made the lake level rise. The second highest lake level stage occurred during 5200 to 3800 a B.P. The climate was cool and wet during 3100 to 2200 a B.P., when the lake expanded with decreasing evaporation. The lake had the last short-term high level during 3100 to 2800 a B.P. After this short high lake level period, the lake shrank because of the long-term lower temperature and reduced water supply. From 2200 to 1200 a B.P., the climate was hot and dry, and the lake shrank greatly. Although the temperature decreased somewhat from 1200 a B.P. to the present, the climate was warm and dry. The lake level began to rise a little again, but it did not reach the river bed altitude of the Konqi River, an outflow river of the Bosten Lake.     

Food,Morality and Identity: mobility,remittances and the translocal community in Paama,Vanuatu

Migration and remittances characterise many small Pacific islands, where local livelihoods are limited, and the need for money has increased. A majority of Paamese have left the island of Paama, in the central island chain of Vanuatu, and more now live in the capital city, Port Vila, than on Paama. Remittances are bidirectional, between the island and Vila, a duality that has rarely been discussed in Melanesia. Almost every household on Paama and in Vila is involved in sending and receiving remittances. Remittances usually involve food: ‘modern’ foods (such as rice) flowing from Vila, and island foods (yams and laplap) travelling to Vila. While such transfers make little formal economic sense, they emphasise a constant process of negotiating and manipulating social relationships. Food, as an expression of identity and locality, is a powerful and repetitive reminder of moral obligations and rural–urban kinship connections. The material significance of exchange is thus less than its affective significance, within the field of reciprocity that structures kin relationships. Food and remittances have become metaphors for defining the experience of migration, as their meaning and function are more than to merely provide a source of nutrition. They have also become the means of structuring a translocal moral economy.     

Impact of early prehistoric farming on chironomid communities in northwest Ireland

This study explored the utility and performance of chironomid (Diptera: Chironomidae) autecology in the investigation of prehistoric farming impacts on freshwater lake systems. Chironomid subfossils, lake sediment geochemistry (δ¹³C, δ¹⁵N and C:N), pollen and macroscopic charcoal analyses were used in a comparative limnological assessment of three archaeologically rich study sites in northwest Ireland. At all three study sites, pastoral farming and its associated nutrient inputs, as represented by non-arboreal pollen indicative of grassland/pasture (NAPp) and lake sediment geochemistry, are concomitant with increases in eutrophic chironomid taxa. Redundancy analysis (RDA) and partial RDAs established that δ¹⁵N and NAPp were controlling factors of chironomid community compositional change during the Neolithic (4000–2500 BC) and Bronze Age (2500–600 BC). Bronze Age farming had a considerably greater impact on the lake systems than Neolithic farming, as indicated by a higher proportion of eutrophic taxa and increases in δ¹⁵N, C:N and δ¹³C values, consistent with increased erosion and agricultural inputs. Findings emphasise the importance of identifying the natural, pre-impacted state of a lake system to determine the extent of agricultural impact accurately. The timing and magnitude of change show that Neolithic and Bronze Age farming exhibited a strong control over chironomid communities at all three sites.     

Airflow patterns in a small subalpine basin

Summary A study of mean wind speeds and directions has been completed in the Snowy Range of Southern Wyoming, U.S.A. It was conducted in a subalpine ecosystem at an altitude of 3 200 m to 3 400 m above sea level during the summers of 1988 and 1989. Indexes of deformation and axes of asymmetry due to wind shaping of Engelmann spruce (Picea engelmannii) and subalpine fir (Abies lasiocarpa) are related to wind speeds and directions on a 100 m × 100 m grid spacing over the 300 ha research site. Isotach and airflow patterns are drawn to represent climatological near-ground-level winds.A statistical analysis of the wind data and deformation indexes indicates that the indexes estimated independently by three of the authors were not significantly different at the F_0.025 level. Two methods of calculating wind speeds were applied. At lower mean wind speeds in Engelmann spruce, results from the Wade-Hewson method were not significantly different from the Griggs-Putnam method at the F_0.025 level. In slightly higher wind speeds in subalpine fir, the Wade-Hewson method produced significantly lower wind speeds than the Griggs-Putnam method.With 3 Figures