Effect of promoted natural feed on the production,nutritional, and immunological parameters of Litopenaeus vannamei (Boone, 1931) semi‐intensively farmed

The effect of promoted biota on the production parameters, water quality, nutritional and immunological condition of Litopenaeus vannamei was assessed in semi‐intensive ponds. Earthen ponds were used as experimental units: three with formulated + natural promoted feed + shrimp (T1), three with formulated feed + shrimp (T2), and three with promoted natural feed without shrimp (Control). The dissolved oxygen (DO) levels were optimal for all treatments (≥6 mg L^?1) as well as the pH (8.4–8.6). Total ammonia nitrogen was greater in T2 (0.10 mg L^?1) than T1 (0.07 mg L^?1) and the Control (0.06 mg L^?1). Phytoplankton, zooplankton and benthos were more abundant in T1 and the Control. The promotion of natural feed had a positive effect on all the production parameters of shrimp with an increase of 19.0%, 3.5% and 23.9% in weight gain, survival, and final biomass, respectively; also it was observed a decrease of 13.9% in feed conversion ratio. No differences in haemolymph parameters were observed for nutritional indicators (glucose, cholesterol, proteins, and triglycerides) nor for immunological response (phenoloxidase and prophenoloxidase). The results indicate that the promotion of biotic communities enhances the production parameters of farmed shrimp, without affecting the nutritional and immunological status. Also the water quality was improved by the presence of biota.     

茶园有害生物防治及农药安全使用

本文阐明了茶园有害生物危害发生的概况及农药使用现状和存在的问题，提出了茶园有害生物管理和措施，安全合理使用农药。     

Motility and migration rate of protozoa in soil columns

Velocity and distances travelled each day by protists in the soil was previously unknown. Soil columns were designed to monitor the distribution of cells along the length of each column as a way to measure migration potential. Motility was affected by pore space, water flow and gravity. The results show that the soil microhabitats that can be explored and exploited by flagellate, amoeboid or ciliated species is in the order of centimetres per day in sandy and sandy loam-textured soil matrices. This value is useful to understand the soil volume that can be explored for food and protist dispersal potential without lateral water flow.     

Comprehensive review of the records of the biota of the Indian Seas and introduction of non‐indigenous species

• 1. Comparison of the pre‐1960 faunal survey data for the Indian Seas with that for the post‐1960 period showed that 205 non‐indigenous taxa were introduced in the post‐1960 period; shipping activity is considered a plausible major vector for many of these introductions.
• 2. Of the non‐indigenous taxa, 21% were fish, followed by Polychaeta (<11%), Algae (10%), Crustacea (10%), Mollusca (10%), Ciliata (8%), Fungi (7%), Ascidians (6%) and minor invertebrates (17%).
• 3. An analysis of the data suggests a correspondence between the shipping routes between India and various regions. There were 75 species common to the Indian Seas and the coastal seas of China and Japan, 63 to the Indo‐Malaysian region, 42 to the Mediterranean, 40 and 34 to western and eastern Atlantic respectively, and 41 to Australia and New Zealand. A further 33 species were common to the Caribbean region, 32 to the eastern Pacific, 14 and 24 to the west and east coasts of Africa respectively, 18 to the Baltic, 15 to the middle Arabian Gulf and Red Sea, and 10 to the Brazilian coast.
• 4. The Indo‐Malaysian region can be identified as a centre of xenodiversity for biota from Southeast Asia, China, Japan, Philippines and Australian regions.
• 5. Of the introduced species, the bivalve Mytilopsis sallei and the serpulid Ficopomatus enigmaticus have become pests in the Indian Seas, consistent with the Williamson and Fitter ‘tens rule’. Included amongst the biota with economic impact are nine fouling and six wood‐destroying organisms.
• 6. Novel occurrences of the human pathogenic vibrios, e.g. Vibrio parahaemolyticus, non‐01 Vibrio cholerae, Vibrio vulnificus and Vibrio mimicus and the harmful algal bloom species Alexandrium spp. and Gymnodinium nagasakiense in the Indian coastal waters could be attributed to ballast water introductions.
• 7. Introductions of alien biota could pose a threat to the highly productive tropical coastal waters, estuaries and mariculture sites and could cause economic impacts and ecological surprises.
• 8. In addition to strict enforcement of a national quarantine policy on ballast water discharges, long‐term multidisciplinary research on ballast water invaders is crucial to enhance our understanding of the biodiversity and functioning of the ecosystem.

Copyright © 2005 John Wiley & Sons, Ltd.     

Management practices to improve soil health and reduce the effects of detrimental soil biota associated with yield decline of sugarcane in Queensland, Australia

Yield decline (YD) of sugarcane is a widespread problem throughout the Australian sugar industry. It is defined as “the loss of productive capacity of sugarcane-growing soil under long-term monoculture”. Factors contributing to YD are the monoculture itself, excessive tillage of the soil at planting and severe soil compaction resulting from the use of heavy machinery during the harvesting operation. Collectively, these crop management practices have led to the development of sugarcane-growing soils that are low in organic C and cation exchange capacity, have a high bulk density and have a low microbial biomass. This in turn is associated with a build up of populations of detrimental soil organisms, which affect the growth and health of the sugarcane root system. Significant yield increases have been demonstrated following pasteurization or fumigation of the soil or treatment of the soil with fungicides or nematicides. Several detrimental soil organisms associated with YD have been identified, including a fungal root pathogen (Pachymetra chaunorhiza) and the lesion nematode (Pratylenchus zeae). Experimental evidence, however, suggests there are many other unidentified detrimental soil organisms associated with YD.

In order to circumvent YD, major changes to the cane cropping system need to be considered. Different rotation breaks (sown pasture, alternate crops, bare fallow) were evaluated for their impact on soil health and the composition of the community of organisms in soil previously under cane monoculture. Despite the breaks having different effects on populations of beneficial soil biota, all breaks reduced populations of known detrimental soil biota and significantly increased the yield of the following cane crop. A single legume-based break crop appeared to be sufficient to capture the majority of these benefits. Other possible management options including the use of organic amendments and minimum tillage techniques are discussed.     

Soil engineering ants increase grass root arbuscular mycorrhizal colonization

The role of edaphic factors in driving the relationship between plant community structure and ecosystem processes is a key issue of the current debate on functional implications of biodiversity. In this study, we draw a direct link between aboveground/belowground relationships, vegetation structure, and aboveground management. We used ground nesting ants and arbuscular mycorrhizal fungi (AMF) as an example for quantifying the role of biotic interactions in soil. Although both groups are known to have a major impact on grasslands, the interactive effect of these taxa on vegetation structure and its sensitivity to grassland management is poorly understood. We show that the ant Lasius flavus increases the root arbuscular mycorrhizal colonization (AMC) of grasses by modifying biotic and abiotic soil properties. As a possible consequence, the shoot length of grass growing on ant mounds was shorter and shoot N and P concentrations were higher than in grass growing off of the mounds. In addition, management affected ant nest architecture and soil and, in turn, AMC. These results emphasize the need to consider the interactions between plants, soil microorganisms, soil fauna, and aboveground management to increase the understanding of the drivers of biodiversity and ecosystem functioning in grasslands both aboveground and belowground.     

地上植食性昆虫对土壤生态系统影响的研究进展

地上地下生态系统之间存在着密切的联系,二者相互作用,共同影响陆地生态系统过程。越来越多的研究表明,地上地下之间的相互联系还受到植食性动物取食作用的调节。地上植食性昆虫不仅可以改变地上植物或动物群落,还可以间接地影响土壤生态系统中的生物群落和相关的土壤过程,进而对地上生态系统形成反馈。本文综述了地上植食性昆虫对土壤食物网中不同营养级的生物群落,以及相关土壤过程的影响;在已有研究报道的基础上,分析并归纳了地上植食性昆虫影响土壤生态系统的途径和调控因素等,旨在较为全面地总结地上植食性昆虫对土壤生态系统的间接影响以及相关的影响机制,并对今后的研究方向作了初步展望。     

Direct and indirect effects of ultraviolet-B radiation on soil biota, decomposition and nutrient fluxes in dune grassland soil systems

 Enhanced UV radiation did not show any effect on the decomposition of a mixed litter of the dune grassland plant species Calamagrostis epigeios and Carex arenaria. Also, leaching of nutrients from lysimeters filled with dune grassland soils was not affected by enhanced UV radiation. Negative UV effects on the fungal biomass in the first part of the experiment were later reversed into positive ones. Clear effects of both UV-A and UV-B were found on Collembola, both on total number of individuals and on the number of species. The decreased number of species under UV radiation could have been due to a decrease in UV-sensitive species. The role of pigmentation is discussed. Received: 6 July 1999     

Making agricultural landscapes more sustainable for freshwater biodiversity: a case study from southern England

• 1. Agriculture is known to have a range of deleterious impacts on freshwater habitats and biota and many countries have introduced measures to attempt to mitigate these impacts through agri‐environment initiatives. Despite the protection they provide, water bodies (any discrete body of surface fresh water) in farmland landscapes commonly remain impaired by agriculture. In some areas of the UK there have been calls to halt farming completely, indicating that the measures offered for the widespread protection of aquatic systems, particularly the use of buffer strips, may not be extensive enough to provide sufficient protection for freshwater biota.
• 2. This study investigated whether existing agri‐environment measures for the widespread protection of aquatic habitats could be better deployed to provide a higher level of protection for the aquatic macrophytes and macroinvertebrates of a study area in southern England.
• 3. Reserve selection procedures were used to reallocate the area of land that could be remunerated under the Environmental Stewardship scheme as buffer strips bordering water bodies, so that a higher level of protection was provided for both the richness and rarity of aquatic species in the study area.
• 4. Almost 395 ha were available for reallocation in the reserve selection process, which was found to provide a satisfactory level of protection for up to 90% of the surveyed species.
• 5. The results showed that the agri‐environment scheme in England has a great deal of potential to provide more effective protection for the aquatic biodiversity of agricultural landscapes if measures are targeted.

Copyright © 2008 John Wiley & Sons, Ltd.