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Marcelo Gomes da Silva Ana Paula Packer Fernanda G. Sampaio Luciano Marani Ericka V. C. Mariano Ricardo A. A. Pazianotto Willian J. Ferreira Plínio C. Alvalá 《Climatic change》2018,150(3-4):195-210
Fisheries and aquaculture are important sources of food for hundreds of millions of people around the world. World fish production is projected to increase by 15% in the next 10 years, reaching around 200 million tonnes per year. The main driver of this increase will be based on fish farming management in developing countries. In Brazil, fish farming is increasing due to the climate conditions and large supply of water resources, with the production system based on Nile tilapia (Oreochromis niloticus) farming in reservoirs. Inland waters like reservoirs are a natural source of methane (CH4) to the atmosphere. However, knowledge of the impact from intensive fish production in net cages on CH4 fluxes is not well known. This paper presents in situ measurements of CH4 fluxes and dissolved CH4 (DM) in the Furnas Hydroelectric Reservoir in order to evaluate the impact of fish farming on methane emissions. Measurements were taken in a control area without fish production and three areas with fish farming. The overall mean of diffusive methane flux (DMF) (5.9?±?4.5 mg CH4 m?2 day?1) was significantly lower when compared to the overall mean of bubble methane flux (BMF) (552.9?±?1003.9 mg CH4 m?2 day?1). The DMF and DM were significantly higher in the two areas with fish farming, whereas the BMF was not significantly different. The DMF and DM were correlated to depth and chlorophyll-a. However, the low production of BMF did not allow the comparison with the limnological parameters measured. This case study shows that CH4 emissions are influenced more by reservoir characteristics than fish production. Further investigation is necessary to assess the impact of fish farming on the greenhouse gas emissions. 相似文献
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Ericka Poppell Jeremy Weisz Lori Spicer Andrew Massaro April Hill Malcolm Hill 《Marine Ecology》2014,35(4):414-424
The ecological and evolutionary forces that shape interactions between marine sponges and their symbiotic microbiota remain poorly understood. Considerable work has been done to characterize the sponge microbiome, and this research has shown that there are two distinct types of sponges: those with high microbial abundances (HMA) and those with low microbial abundances (LMA). There is no clear evolutionary driver for this distinction, and we have only a limited understanding of how HMA or LMA status affects host phenotypes (e.g. feeding behavior, capacity for nutrient cycling). We had two primary goals with the present study. First, we used a variety of microscopic techniques to compare aspects of host biology (e.g. choanocyte chamber morphology and density) in the context of symbiont status. Secondly, we used molecular approaches to uncover components of ecological structure of bacterial communities in HMA versus LMA sponges (e.g. species richness, evenness). We found that choanocyte chamber density is greater in LMA sponges than in HMA sponges. We also found distinct patterns of organization for bacterial communities in HMA and LMA sponges, although environmental factors, to a lesser degree, also influence community structure in the Floridian sponges we examined. These results suggest that the large bacterial communities found in HMA sponges may allow the host to decrease their heterotrophy versus that of LMA sponges with minimal bacterial communities. 相似文献
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Surface water samples from marinas, commercial ports and open bay areas collected from Biscayne Bay and the Miami River, Florida, USA, were analyzed for the occurrence of IRGAROL 1051 by GC/MS. The anifouling boosting herbicide was found in 80% (46/57) of the samples collected between March 1999 and September 2000. Concentrations within the bay range between non-detected (<1 ppt) and 61 ppt (ng/L) and were generally low compared with levels reported in European or Japanese waters. Aside from the elevated concentrations observed along the Miami River South Fork (61 ppt), the highest concentrations observed in the bay corresponded to marinas with high density of pleasure craft and restricted water circulation. In contrast, occurrence of IRGAROL 1051 along the commercial port or the cruise line terminal was generally lower (<1-2.2 ppt). Concentrations around Coconut Grove Marina were consistently higher (5-12 ppt) than the rest of the bay waters during the whole period of time surveyed. 相似文献
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