Diel Cycling of Zinc in a Stream Impacted by Acid Rock Drainage: Initial Results from a New in situ Zn Analyzer

Recent work has demonstrated that many trace metals undergo dramatic diel (24-h) cycles in near neutral pH streams with metal concentrations reproducibly changing up to 500% during the diel period (Nimick et al., 2003). To examine diel zinc cycles in streams affected by acid rock drainage, we have developed a novel instrument, the Zn-DigiScan, to continuously monitor in situ zinc concentrations in near real-time. Initial results from a 3-day deployment at Fisher Creek, Montana have demonstrated the ability of the Zn-DigiScan to record diel Zn cycling at levels below 100 μg/l. Longer deployments of this instrument could be used to examine the effects of episodic events such as rainstorms and snowmelt pulses on zinc loading in streams affected by acid rock drainage.     

Effects of Cadmium (CdCl2) on development and hatching of eggs in European squid (Loligo vulgaris Lamarck, 1798) (Cephalopoda: Loliginidae)

This is the first study related to the effects of cadmium (Cd) on the development and hatching of eggs of Loligo vulgaris. The eggs were exposed to concentrations varying from 10 to 100,000 μg Cd/l for up to 1 month. During the study period natural sea water salinity (37 PSU), ambient temperature (ranging 16.5–21.5°C) and light conditions of 12-h light: 12-h dark for 744-h were used prior to the hatching. For 96-h, mortality rate of 100% of the eggs was found at cadmium concentration of 100,000 μg Cd/l, and the same mortality rate of the eggs were found at 1,000 and 10,000 μg Cd/l for 744-h and 696-h, respectively. Hatching took place between hours 456 and 576 in the control group and between hours 480 and 576 in 10 and 100 μg Cd/l groups. Total hatching rates were calculated to be 98.2 ± 1.6% for control group, 99.4 ± 0.6% for 10 μg Cd/l group and 98.6 ± 1.2% for 100 μg Cd/l group. Hatching successes were estimated as 69.5 ± 13.8% for control group, 84.5 ± 8.2% for 10 μg Cd/l group and 76.9 ± 5.9% for 100 μg Cd/l group. In the 100,000 μg Cd/l treatment, the egg degeneration began from animal pole of the eggs in 16 h, and 50% and 100% of them died in the initial stage at 72-h and 96-h, respectively. In the 10,000 μg Cd/l group, the eggs which reached at stage 19 (IX) were deformed and 50% and 100% of them died at 312-h and 696-h, respectively. In 1,000 μg Cd/l group, however, the eggs developed abnormally from stage 21 (X–XI) and reached at stage 29 (XIX), and 50% and 100% of them died in 624-h and in 744-h, respectively. There were significant differences in survival rates of the eggs among the concentrations (p < 0.05). The current study demonstrated that Cd adversely affects the development, survival and hatching of L. vulgaris eggs; however, no mortality was observed in 10 μg Cd/l and 100 μg Cd/l groups.     

Influence of weight on the content of trace metals in tissues of Mytilus galloprovincialis (Lamarck, 1819): a forecast model

Fifty seven samples of Mytilus galloprovincialis (Lamarck, 1819) collected along the breakwater barriers of Fano (station 1) and Pesaro (station 2), Adriatic Sea, Marche Region, central Italy, were analyzed by atomic absorption spectrometry and Cd, Cu, Pb and Zn concentrations in the soft tissues were measured. The aims of this work were the statistical analysis of Cd-weight, Cu-weight, Pb-weight, Zn-weight relationships, and the building of a tendency function that allows assessing with a good approximation the concentrations of a metal in different weight organisms. In Mytilus galloprovincialis the content of Cd proportionally grew with the weight and therefore its concentration was independent from this factor; while the concentration of Pb decreased as the weight increased. In both cases the accuracy of multiple regression models improved considering the variable ‘site’, while the same approach appeared not reliable for Cu and Zn, that were two essential metals. Our results showed that a tendency function was reliable, solid and able to predict to a very satisfying extent the concentration of non-physiological metals, like Cd and Pb; while it did not show a good approximation with real Cu and Zn contents.     

Directional Connectivity of Wolf (Canis lupus) Populations in Northwest Spain and Anthropogenic Effects on Dispersal Patterns

In view of the extensive information available on wolf ecology and habitat suitability, and on the fragmentation of wolf populations by motorways and similar infrastructures, a key factor in their conservation, the aim of the present study was to model the directional connectivity of wolf populations in the region of Galicia in northwest Spain, and to quantify anthropogenic effects on wolf dispersal patterns. To this end, we map the probability of wolf movement by means of known relationships between wolf movement and anthropogenic, vegetation and topographic factors. The relative importance of each factor was quantified by sensitivity analyses. Three types of cost surface were constructed: (a) isotropic surfaces, (b) anisotropic cost surfaces taking into account terrain slope effects in the movement, and (c) surfaces obtained by combining the isotropic and anisotropic surfaces. The results obtained by approaches (a) and (c) indicate that one of the region’s motorways (the AP-9) probably acts as a significant barrier to wolf movement, possibly isolating two subpopulations, while the remaining motorways probably do not have major effects on dispersal. Estimation of lowest-cost routes for wolf displacement allowed identification of areas critical for connectivity, in which it would be of interest to perform detailed studies with more precise input data on motorway course and the location of drainage channels and underpasses, etc. (these being the factors identified by sensitivity analysis to be those with the most marked effects on the cost surfaces). The visualization of connectivity enabled by this approach will allow wolf management and conservation efforts to be focused on critical areas: such efforts might include measures aimed to encourage wolf dispersal through areas in which conflict with human activity is minimized, thus contributing positively to the management of a socially conflictive species. Finally, evaluation of the different cost surfaces suggests that it would be of interest to introduce two modifications to the anisotropic algorithm, to allow the user to weigh the importance of the different input factors, and to allow the inclusion of more than one anisotropic factor in the model.     

Assessing effects of ambient ozone on injury and yield of bean with ethylenediurea (EDU): three years of plant monitoring at four sites in The Netherlands

EDU (ethylenediurea) and non-EDU-treated bean plants (Phaseolus vulgaris) L. cv. Lit) were exposed to ambient air at four rural sites in the Netherlands during the growing seasonsof 1994 through 1996 to investigate the responses to ambient ozone. Ozone-induced foliar injury was observed each year anddifferences in injury between sites depended on year. On average,injury amounted to 27% in 1994, to 8% in 1995 and to 1% in 1996. Injury increased with increasing ozone exposure (AOT40) and the estimated AOT40 value corresponding with 5% injury wascirca 3650 nl l^-1 h ozone. The highest ozone levels accumulated at each site for five consecutive days before injuryexceeded the proposed short-term critical level for injury development. EDU reduced injury and its protective effect was positively related to the injury intensity in non-EDU-treatedplants. Yield of green marketable pods (intermediate harvest) andmature pods (final harvest) was generally reduced in non-EDU-treated plants compared to EDU-treated plants and differences inyield reduction between harvests varied between years. The yield of mature pods was reduced in 1994 and 1996 while the yield ofgreen pods was reduced in 1995 by ozone only. Since yield reduction was not correlated with AOT40, the EDU method was notvalid to determine an ozone exposure-yield reponse relationshipfor bean.