Translocation of fixed carbon from symbiotic bacteria to host tissues in the gutless bivalve Solemya reidi

Naturally-occurring lipophilic inducers of larval settlement and metamorphosis wer isolated and identified for Phragmatopoma californica, a gregarious tube worm from southern California. Organic solvent extraction of the sand/organic cement matrix of tubes diminished the inducing capacity of the tube matrix. The inducing capacity was restricted to a single, highly active, HPLC-purified fraction of the organic solvent extract. Chemical analysis of this fraction revealed a mixture of free fatty acids (FFAs), dominated by eicosapentaenoic acid (20:5, 20%), palmitic acid (16:0, 14%) and palmitoleic acid (16:1, 12%). In assays of the nine FFAs that each contributed 3% or more to the active fraction, only 16:1, 18:2, 20:4 and 20:5 induced larval settlement and metamorphosis, while the others were ineffective. The larval response was contact-dependent, highly specific, and concentration-dependent, with a significant response to 16:1 and 20:4 at as low as 10 g FFA spread onto 1 g of sand (surface area 36 cm²). Active FFAs were extracted at approximately 14 g g^-1 sand from the tube matrix, although the levels encountered by larvae in nature are believed to be higher.     

Atmospheric deposition of polycyclic aromatic hydrocarbons near New England coastal waters

Wet and dry deposition of polycyclic aromatic hydrocarbons (PAHs) was measured at Nahant, Massachusetts, a peninsula jutting into Massachusetts Bay and Wolf Neck, a peninsula jutting into Casco Bay, Maine. Wet deposition (rain and snow) was collected in a funnel which drains into a shielded, temperature controlled receiving bottle. Dry deposition of gaseous and particulate PAHs was collected onto an exposed water surface. PAHs were analyzed by solid phase extraction and gas chromatography-mass spectrometry. Sixteen PAH species were analyzed, ranging from acenaphthylene to coronene. The mean wet deposition rate of the sum of the 16 species is 720 ng m⁻² cm⁻¹ precipitation at Nahant, and 831 ng m⁻² cm⁻¹ precipitation at Wolf Neck. Wet deposition is attributed to regional PAH emitting sources. Storm patterns appear to bring somewhat higher wet deposition of PAHs to Wolf Neck than to Nahant. The mean dry deposition rate is 95 ng m⁻² h⁻¹ at Nahant and 9.3 ng m⁻² h⁻¹ at Wolf Neck. The large difference is attributed to the fact that Nahant is close to the urban-industrial metropolitan Boston area and Logan International Airport, whereas Wolf Neck has no major PAH-emitting sources nearby. Individual measurements have an error bracket of ±30%. The Chemical Mass Balance model was used to apportion the dry deposition to source categories. At Nahant, nine samples gave valid statistical attributes with a mean apportionment: jet exhaust 35%, gasoline fueled vehicles 32%, diesel fueled vehicles 17%, wood combustion 13%, others 3%. At Wolf Neck, six samples yielded a mean apportionment: jet exhaust 30%, gasoline vehicles 28%, diesel vehicles 18%, wood combustion 16%, others 8%. There is a considerable variation between the samples. The apportionment is greatly dependent on the quality and selection of the model inputs, i.e. source signatures, which for PAHs are questionable.     

Assessing high-impact spots of climate change: spatial yield simulations with Decision Support System for Agrotechnology Transfer (DSSAT) model

Drybeans (Phaseolus vulgaris L.) are an important subsistence crop in Central America. Future climate change may threaten drybean production and jeopardize smallholder farmers’ food security. We estimated yield changes in drybeans due to changing climate in these countries using downscaled data from global circulation models (GCMs) in El Salvador, Guatemala, Honduras, and Nicaragua. We generated daily weather data, which we used in the Decision Support System for Agrotechnology Transfer (DSSAT) drybean submodel. We compared different cultivars, soils, and fertilizer options in three planting seasons. We analyzed the simulated yields to spatially classify high-impact spots of climate change across the four countries. The results show a corridor of reduced yields from Lake Nicaragua to central Honduras (10–38 % decrease). Yields increased in the Guatemalan highlands, towards the Atlantic coast, and in southern Nicaragua (10–41 % increase). Some farmers will be able to adapt to climate change, but others will have to change crops, which will require external support. Research institutions will need to devise technologies that allow farmers to adapt and provide policy makers with feasible strategies to implement them.     

Mapping socio-economic scenarios of land cover change: a GIS method to enable ecosystem service modelling

We present a GIS method to interpret qualitatively expressed socio-economic scenarios in quantitative map-based terms. (i) We built scenarios using local stakeholders and experts to define how major land cover classes may change under different sets of drivers; (ii) we formalized these as spatially explicit rules, for example agriculture can only occur on certain soil types; (iii) we created a future land cover map which can then be used to model ecosystem services. We illustrate this for carbon storage in the Eastern Arc Mountains of Tanzania using two scenarios: the first based on sustainable development, the second based on 'business as usual' with continued forest-woodland degradation and poor protection of existing forest reserves. Between 2000 and 2025 4% of carbon stocks were lost under the first scenario compared to a loss of 41% of carbon stocks under the second scenario. Quantifying the impacts of differing future scenarios using the method we document here will be important if payments for ecosystem services are to be used to change policy in order to maintain critical ecosystem services.     

Histopathological alterations in hepatopancreas of Gafrarium divaricatum exposed to xylene, benzene and gear oil-WSF

Gafrarium divaricatum were exposed to xylene (4.25 and 8.50 mg l(-1)), benzene (4.35 and 8.70 mg l(-1)) and gear oil-WSF (1 and 2%) for 30 days. Chronic exposure of clams to the pollutants resulted in loss of bubbling epithelium, reduction in cytoplasm volume and density, fusion of cell membranes and nuclei forming darkly stained area at basal part of the cells. Disintegration of basement membrane due to damaged epithelial cells, disruption of inner lining of tubule, formation of necrotic spaces, separation of epithelial cells from basement membrane, increase in internal luminar area, complete necrosis of epithelial cells as well as occurrence of cell debris in between the tissue were also observed in the clams due to chronic exposure of the toxicants.     

BIOLOGICAL MONITORING OF BLUEGILL ACTIVITY1

ABSTRACT: Bluegills were exposed for one hour to 0.2 or 2.3 mg/liter water soluble fraction (WSF) of JP-4 in a testing chamber designed to contain individual fish. A strain gage paddle was used to monitor activity. Whole body movement of individual fish did not change appreciably during exposure to either 0.2 or 2.3 mg/liter WSF-JP-4. Strength of pectoral fin movement, accounting for the majority of the fish behavior, increased in six of ten individuals exposed to 2.3 mg/liter WSF-JP-4. Pectoral fanning may be a useful parameter to indirectly assess water quality.     

Winged queens replaced by reproductives smaller than workers in <Emphasis Type="Italic">Mystrium</Emphasis> ants

In ants, winged queens that are specialized for independent colony foundation can be replaced by wingless reproductives better adapted for colony fission. We studied this shift in reproductive strategy by comparing two Mystrium species from Madagascar using morphometry, allometry and dissections. Mystrium rogeri has a single dealate queen in each colony with a larger thorax than workers and similar mandibles that allow these queens to hunt during non-claustral foundation. In contrast, Mystrium ‘red’ lacks winged queens and half of the female adults belong to a wingless ‘intermorph’ caste smaller and allometrically distinct from the workers. Intermorphs have functional ovaries and spermatheca while those of workers are degenerate. Intermorphs care for brood and a few mate and reproduce making them an all-purpose caste that takes charge of both work and reproduction. However, their mandibles are reduced and inappropriate for hunting centipedes, unlike the workers’ mandibles. This together with their small thorax disallow them to perform independent colony foundation, and colonies reproduce by fission. M. rogeri workers have mandibles polymorphic in size and shape, which allow for all tasks from brood care to hunting. In M. ‘red’, colonial investment in reproduction has shifted from producing expensive winged queens to more numerous helpers. M. ‘red’ intermorphs are the first case of reproductives smaller than workers in ants and illustrate their potential to diversify their caste system for better colonial economy.