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Havenhand JN 《Ambio》2012,41(6):637-644
Increasing partial pressure of atmospheric CO2 is causing ocean pH to fall—a process known as ‘ocean acidification’. Scenario modeling suggests that ocean acidification in the Baltic Sea may cause a ≤3 times increase in acidity (reduction of 0.2–0.4 pH units) by the year 2100. The responses of most Baltic Sea organisms to ocean acidification are poorly understood. Available data suggest that most species and ecologically important groups in the Baltic Sea food web (phytoplankton, zooplankton, macrozoobenthos, cod and sprat) will be robust to the expected changes in pH. These conclusions come from (mostly) single-species and single-factor studies. Determining the emergent effects of ocean acidification on the ecosystem from such studies is problematic, yet very few studies have used multiple stressors and/or multiple trophic levels. There is an urgent need for more data from Baltic Sea populations, particularly from environmentally diverse regions and from controlled mesocosm experiments. In the absence of such information it is difficult to envision the likely effects of future ocean acidification on Baltic Sea species and ecosystems. 相似文献
2.
F. A. Kohout J. C. Hathaway D. W. Folger M. H. Bothner E. H. Walker D. F. Delaney M. H. Frimpter E. G. A. Weed E. C. Rhodehamel 《Journal of the American Water Resources Association》1977,13(2):373-386
ABSTRACT: A deep water-resource and stratigraphic test well near the center of Nantucket Island, about 40 miles (64 km) off the New England Coast, has encountered freshwater at greater depth than predicted by the Ghyben-Herzberg principle. An uppermost lens of fresh-water, which occupies relatively permeable glacial-outwash sand and gravel to a depth of 520 ft. (158 m), is probably in hydrodynamic equilibrium with the present level of the sea and the height of the water table. However, two zones of freshwater between 730-820 ft. (222-250 m) and 900-930 ft. (274-283 m) are anomalously deep. A third zone extending from 1150-1500 ft. (350-457 m) contains slightly salty ground water (2 to 3 parts per thousand dissolved solids). Several explanations are possible, but the most likely is that large areas of the Continental Shelf were exposed to recharge by precipitation during long periods of low sea level in Pleistocene time. After the last retreat of glacial ice, seawater rapidly drowned the shelf around Nantucket Island. Since then, about 8000 years ago, the deep freshwater zones which underlie dense clay layers have not had time to adjust to a new equilibrium. Under similar circumstances freshwater may remain trapped under extensive areas of the Continental Shelf wherever clay confining beds have not permitted saltwater to intrude rapidly to new positions of hydrodynamic equilibrium. The implications are far reaching because all continental shelfs were exposed to similar hydrologic influences during Pleistocene time. 相似文献
3.
A. Simms 《Journal of Coastal Conservation》2002,8(1):35-48
The 1992 collapse of the northern cod fishery at Newfoundland, Canada and the subsequent closure of a majority of the inshore
ground fishery has placed a focus on the development of aquaculture within the province. In May 1995 Innovative Fisheries
Inc. of St. John's, Newfoundland, conducted field studies to evaluate the soft-shell clam (edible bivalve molluscs) resources
on three sand flats near Burgeo, Newfoundland. GIS can be used to examine issues regarding the development and management
of the soft-shell clam beds. GIS can also be applied to examine the issue of ‘competing uses’ for the proposed soft-shell
clam aquaculture site. The information presented in this study indicates that GIS is an important tool for the aquaculture
industry. These systems can be used to monitor, quantify and evaluate the soft-shell beds near Burgeo. Management issues such
as water quality, resource sustainability as well as the economic viability of the clam resource can be assessed within a
GIS environment. The results of the analysis in this study suggest potential problems with faecal coliform contamination from
local cottages. Finally, data collection for aquaculture site assessment is required if a resource is to be managed effectively.
GIS applications provide insights into the quality of the physical environment as well as the sustainability of a resource.
However, it is the aquaculture operators who ultimately make the final decisions. 相似文献
4.
Outi Heikinheimo 《Ecological modelling》2011,222(10):1731-1742
The interactions between cod (Gadus morhua), herring (Clupea harengus) and sprat (Sprattus sprattus) in the Central Baltic Sea were examined with a simple dynamic model, an alternative to more complicated and data-demanding multispecies and ecosystem models. The main aims of the study were to compare the effect of alternative structures on the model output and examine the control relationships in the fish assemblage under different environmental conditions. The effect of environmental conditions was modelled using a stock-recruitment equation for cod incorporating an environmental index. The model output was especially sensitive to the functional response in predation by cod on herring and sprat. The type II functional response led to a collapse of the clupeid stocks when cod was abundant, while the type III response produced more realistic stock dynamics. According to the simulations, an abundant cod stock was able to keep the sprat stock at a low level, while the herring stock was less affected and benefited from the decreased density of sprat. Simulation of different fishing scenarios indicated that reducing fishing mortality to the level currently advised by ICES would allow the recovery of the cod stock even in unfavourable environmental conditions. 相似文献
5.
Timothy D. McCobb Denis R. LeBlanc Roy S. Socolow 《Journal of the American Water Resources Association》1999,35(5):1141-1146
A device that uses a siphon tube to establish a hydraulic connection between the bottom of an onshore standpipe and a point at the bottom of a water body was designed and tested for monitoring surface-water levels. Water is added to the standpipe to a level sufficient to drive a complete slug of water through the siphoning tube and to flush all air out of the system. The water levels in the standpipe and the water body equilibrate and provide a measurable static water surface in the standpipe. The siphon gage was designed to allow quick and accurate year-round measurements with minimal maintenance. Currently available devices for monitoring surface-water levels commonly involve time-consuming and costly installation and surveying, and the movement of reference points and the presence of ice cover in cold regions cause discontinuity and inaccuracy in the data collected. Installation and field testing of a siphon gage using 0.75-in-diameter polyethylene tubing at Ashumet Pond in Falmouth, Massachusetts, demonstrated that the siphon gage can provide long-term data with a field effort and accuracy equivalent to measurement of ground-water levels at an observation well. 相似文献
6.
By mainly targeting larger predatory fish, commercial fisheries have indirectly promoted rapid increases in densities of their
prey; smaller predatory fish like sprat, stickleback and gobies. This process, known as mesopredator release, has effectively
transformed many marine offshore basins into mesopredator-dominated ecosystems. In this article, we discuss recent indications
of trophic cascades on the Atlantic and Baltic coasts of Sweden, where increased abundances of mesopredatory fish are linked
to increased nearshore production and biomass of ephemeral algae. Based on synthesis of monitoring data, we suggest that offshore
exploitation of larger predatory fish has contributed to the increase in mesopredator fish also along the coasts, with indirect
negative effects on important benthic habitats and coastal water quality. The results emphasize the need to rebuild offshore
and coastal populations of larger predatory fish to levels where they regain their control over lower trophic levels and important
links between offshore and coastal systems are restored. 相似文献
7.
Anne Gro Vea Salvanes Victoria A. Braithwaite 《Behavioral ecology and sociobiology》2005,59(2):250-257
Many re-introduction programs used for conservation of populations and species threatened with extinction advocate the use of enriched rearing environments to train animals how to behave appropriately in the wild. Curiously, most of the current fish re-stocking programs have paid little attention to lessons previously learned in bird and mammal re-introductions. Many rehabilitation programs that use releases of hatchery fish observe higher mortality in released fish compared to wild, with most mortality arising shortly after release. One explanation for this mortality is based purely on selection processes; many hatchery fish normally selected out of the population thrive in the predator free, food-rich hatcheries. Alternatively, mortalities may be high because hatchery nursery environments fail to shape fish behaviour appropriately. Here, we empirically address the effect of enrichment in the early rearing environment in coastal cod (Gadus morhua). We find asymmetries in aggressive behaviour when fish reared in plain or enriched environments are allowed to interact. Furthermore, cod reared in standard, impoverished, hatchery environments spend less time in shelter, are more active, and show weaker anti-predator responses than fish reared with access to heterogeneous spatial cues. These results suggest that the constant, plain environments of fish farms may generate behavioural deficits that could reasonably be expected to be associated with lower survival in fish released into the wild. 相似文献
8.
Kent DB Davis JA Joye JL Curtis GP 《Environmental pollution (Barking, Essex : 1987)》2008,153(1):44-52
Adsorption of Ni and Pb on aquifer sediments from Cape Cod, Massachusetts, USA increased with increasing pH and metal-ion concentration. Adsorption could be described quantitatively using a semi-mechanistic surface complexation model (SCM), in which adsorption is described using chemical reactions between metal ions and adsorption sites. Equilibrium reactive transport simulations incorporating the SCMs, formation of metal-ion-EDTA complexes, and either Fe(III)-oxyhydroxide solubility or Zn desorption from sediments identified important factors responsible for trends observed during transport experiments conducted with EDTA complexes of Ni, Zn, and Pb in the Cape Cod aquifer. Dissociation of Pb-EDTA by Fe(III) is more favorable than Ni-EDTA because of differences in Ni- and Pb-adsorption to the sediments. Dissociation of Ni-EDTA becomes more favorable with decreasing Ni-EDTA concentration and decreasing pH. In contrast to Ni, Pb-EDTA can be dissociated by Zn desorbed from the aquifer sediments. Variability in adsorbed Zn concentrations has a large impact on Pb-EDTA dissociation. 相似文献
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