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Effects of suspended sediments on egg production of the calanoid copepod Acartia tonsa 总被引:1,自引:0,他引:1
The estuarine copepod Acartia tonsa was collected on several occasions between 4 April and 14 August 1985 from Terrebonne Bay, Louisiana (29°08N; 90°36W) and the effects in its diet of suspended sediments, collected from the same area, were measured at five different concentrations of sediment (100 to 1 000 ppm) and six phytoplankton concentrations (500 to 13 000 cells ml-1
Thalassiosira weissflogii). Egg production rate was used as an index of diet quality. At low phytoplankton concentrations (500 cells ml-1), and at intermediate phytoplankton concentrations (2 000 cells ml-1) for previously starved copepods, egg production was reduced by up to 40% at a sediment concentration of 250 ppm and further reduced at higher sediment concentrations. At higher food concentrations (4 000 to 13 000 cells ml-1), suspended sediment had no effect on egg production rates at sediment concentrations up to 500 ppm. Rates were reduced only at the highest sediment concentration of 1 000 ppm. Under most natural conditions, suspended sediment would not significantly affect egg production rates in A. tonsa. 相似文献
2.
Relationships between growth rate and RNA,DNA, protein and dry weight in Artemia salina and Euchaeta elongata 总被引:1,自引:0,他引:1
The concentrations of RNA, DNA and protein, and the dry weight in 3 cultures of the anostracan Artemia salina (L.) were measured to investigate the usefulness of the RNA-growth relationship in estimating growth or productivity. Similar analyses were performed on Copepodid stages III to VI of the calanoid copepod Euchaeta elongata Esterly collected periodically over 7 months in Haro Strait and over 4 months in Saanich Inlet, British Columbia, Canada. It was found that the RNA-growth relationship derived by Sutcliffe (1965) did not agree with that found for A. salina in this study. Also, neither equation accurately predicted growth rates for E. elongata copepodids. It is concluded that the general positive relationship between RNA concentration and growth rate lacks sufficient specificity to be used as a method for predicting growth rates in these species. 相似文献
3.
The case is made in this paper for early and integrative public participation in planning decisions concerning proposals major
development in the zone. This is perhaps easy to subscribe to in theory but much more difficult in practice. Currently the
extent and timing of public involvement in such decisions varies widely. A key benefit is the legitimacy that public participation
provides to the planning process and, perhaps as a result, a variety of public involvement methodologies have emerged. Important
considerations include which sections of the public to involve and at what stage in the decision-making process to involve
them. The multidisciplinary nature of coastla zone issues will tend to engage a wide variety of stakeholder groups who in
turn will influence the topics for discussion. A major port expansion proposal in the UK is used to illustrate a range of
ways in which the public can be involved. The case study also highlights that public participation is an uncertain science,
and to be successful can require skilled personnel and significant resources. The papper concludes that more guidance for
developers, some standardisation of public involvement, training for facilitatiors and a more responsible stance from some
environmental pressure groups would be advantageous. The complexity of coastal decision-making, tensions between science and
policy, and the inter-dependency of coastal activities mutually reinforce the view that inclusive participation is an important
issue for all coastal communities. 相似文献
4.
M. J. Dagg 《Marine Biology》1983,75(1):63-67
An experimental technique for measuring the feeding behavior of copepods on small time scales is important because grazer/micro-patch interactions in the ocean are probably short (minutes to hours). By placing copepods with empty guts into a known food concentration and monitoring the rate of increase in gut contents until defecation begins, usually 20 to 100 min, the volume of water swept clear of particles per min can be calculated. This process is easily quantified by using phytoplankton as food and measuring the gut contents by fluorometry. The utility of this technique is demonstrated in the laboratory and at sea. 相似文献
5.
BioScene (scenarios for reconciling biodiversity conservation with declining agriculture use in mountain areas in Europe)
was a three-year project (2002–2005) funded by the European Union’s Fifth Framework Programme, and aimed to investigate the
implications of agricultural restructuring and decline for biodiversity conservation in the mountain areas of Europe.
The research took a case study approach to the analysis of the biodiversity processes and outcomes of different scenarios
of agri-environmental change in six countries (France, Greece, Norway, Slovakia, Switzerland, and the United Kingdom) covering
the major biogeographical regions of Europe. The project was coordinated by Imperial College London, and each study area had
a multidisciplinary team including ecologists and social and economic experts, which sought a comprehensive understanding
of the drivers for change and their implications for sustainability.
A key component was the sustainability assessment (SA) of the alternative scenarios. This article discusses the development
and application of the SA methodology developed for BioScene. While the methodology was objectives-led, it was also strongly
grounded in baseline ecological and socio-economic data. This article also describes the engagement of stakeholder panels
in each study area and the use of causal chain analysis for understanding the likely implications for land use and biodiversity
of strategic drivers of change under alternative scenarios for agriculture and rural policy and for biodiversity management.
Finally, this article draws conclusions for the application of SA more widely, its use with scenarios, and the benefits of
stakeholder engagement in the SA process. 相似文献
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