不同环境因子对草履虫种群生长的影响

为了研究不同环境因子对草履虫种群生长的影响,培养出优质的草履虫,分别在pH梯度为:6.0、6.5、7.0、7.5、8.0,光照梯度为:0lx、500lx、1 000lx、1 500lx条件下培养草履虫,结果表明,小白菜培养液培养草履虫的最适pH值为7.0,并且相比于弱酸性环境,草履虫更适宜在弱碱性环境中生长。在光照为0lx条件下,草履虫数量在第4天时达到最大值4 073ind/100mL,在光照为500~1 500lx条件下,随着光照度的增加,草履虫的种群数量也随之增加。     

Apparent digestibility coefficients of animal and plant feed ingredients for juvenile Pseudobagrus ussuriensis

A study was conducted to determine apparent digestibility coefficients (ADCs) of dry matter (DM), crude protein (CP), lipid, gross energy, phosphorus and amino acids (AAs) from Peruvian fish meal (PFM), native fish meal (NFM), meat bone meal (MBM), dried daphnia meal (DDM), soybean meal (SBM), full‐fat soybean (FSBM), cottonseed meals (CSM), rapeseed meal (RSM) and corn gluten meal (CGM) for Pseudobagrus ussuriensis (7.8 ± 0.06 g). Test diets were formulated to contain a 70:30 mixture of reference diet to test ingredient with chromic oxide (5 g kg^–1) serving as the inert marker. ADCs of DM ranged from 49.94% (CGM) to 87.11% (PFM), the highest ADCs of DM were observed in PFM and the lowest was found in CGM. ADCs of CP in the test ingredients ranged from 74.92% (CGM) to 93.41% (SBM). ADCs of crude lipid ranged from 51.80% (CGM) to 94.07% (PFM) for fish. ADCs of energy ranged from 56.42% (CGM) to 90.09% (PFM). ADCs of phosphorus ranged from 21.81% (CSM) to 65.70% (PFM). AA availability for the test ingredients followed a similar pattern to ADCs of CP, in which values for PFM, NFM and MBM were generally higher (p < .05) than those of other protein ingredients. Among all plant meals, the AA availability values in SBM were higher (p < .05) than those in CGM, CSM and RSM. The availability of most AAs in CGM was the lowest (p < .05) among all tested ingredients. In conclusion, PFM and NFM are good sources of available protein and AAs. When fishmeal supply is limited, MBM and DDM are substitutes for fishmeal reduction in P. ussuriensis diets; at the same time, SBM and FSBM are also very acceptable protein feedstuffs. However, CSM, RSM and CGM could not be used at high levels in P. ussuriensis diets because of their inferior digestibilities.     

Cyprinid herpesvirus 3 as a potential biological control agent for carp (Cyprinus carpio) in Australia: susceptibility of non‐target species

Carp (Cyprinus carpio L.) is a pest species in Australian waterways, and cyprinid herpesvirus 3 (CyHV‐3) is being considered as a potential biological control (biocontrol) agent. An important consideration for any such agent is its target specificity. In this study, the susceptibility to CyHV‐3 of a range of non‐target species (NTS) was tested. The NTS were as follows: 13 native Australian, and one introduced, fish species; a lamprey species; a crustacean; two native amphibian species (tadpole and mature stages); two native reptilian species; chickens; and laboratory mice. Animals were exposed to 100–1000 times the approximate minimum amount of CyHV‐3 required to cause disease in carp by intraperitoneal and/or bath challenge, and then examined clinically each day over the course of 28 days post‐challenge. There were no clinical signs, mortalities or histological evidence consistent with a viral infection in a wide taxonomic range of NTS. Furthermore, there was no molecular evidence of infection with CyHV‐3, and, in particular, all RT‐PCRs for viral mRNA were negative. As a consequence, the results encourage further investigation of CyHV‐3 as a potential biocontrol agent that is specific for carp.     

Fluorescence of Extracts from Argentine Hake (Merluccius hubbsi) Muscle and Its Correlation with Quality Indices During Chilled Storage

Argentine hake (Merluccius hubbsi) was stored chilled for 8 days. The evolution of fluorescence of the aqueous and organic extracts of muscle during storage at 4°C was studied and correlated with common damage indices; pH, total volatile basic nitrogen, free fatty acids, and the fluorescence intensity of the aqueous phase showed a good correlation with storage time. The excitation-emission matrices of the aqueous extracts were also obtained. A fluorescence landscape that could be attributed to tryptophan decreased with storage time, meanwhile a peak (around 340 and 400 nm for excitation and emission wavelengths, respectively) is developed during chilled storage.     

Interactions of baseflow habitat constraints: Macroinvertebrate drift,stream temperature,and physical habitat for anadromous salmon in the Calapooia River,Oregon

1. The Calapooia River in western Oregon supports a small winter steelhead trout (Oncorhynchus mykiss) population and historically supported spring Chinook salmon (Oncorhynchus tshawytscha). Early timber harvesting removed the riparian forest, and log transportation practices simplified the channel. Those disturbance legacies continue to affect fish habitat by limiting shade and channel complexity, complicating conservation efforts.
2. To evaluate juvenile salmonid rearing potential, macroinvertebrate drift, thermal regime and physical habitat were measured at eight sites in 24 km of the upper river during late summer baseflow.
3. Overall physical habitat was simple, with few functioning instream structures or pools. During the 22‐day drift study, flows declined and maximum site stream temperatures ranged from 23.1°C at the lower end to 16.4°C 24 km upstream.
4. Macroinvertebrate drift concentrations ranged from 0.7–13.7 ind. m^?3 with biomasses from 0.02–1.23 mg m^?3. Drift concentration biomass was higher upstream (P  = 0.006) than downstream and declined overall (P  < 0.001) during the study. Drift biomass was dominated by five taxon groups – Baetis tricaudatus, Calineuria californica, Hesperoperla pacifica, Simulium spp., and Chironomidae, which were 65% of total biomass. During twilight, total biomass and biomass of B. tricaudatus, Simulium spp., and Chironomidae (both larvae and adults) were higher.
5. Total drift declined dramatically over the study period owing to decreases in drift concentration and a 58% decline in discharge, greatly reducing overall drift and available food resources for juvenile‐rearing salmonids.
6. The upper catchment, both with cooler temperatures and higher food availability, provided the best conditions for juvenile anadromous salmonids to survive late summer conditions. Conservation consequences of climate change‐induced alterations in flow and temperature may further affect habitat quality for juvenile salmonids in this catchment in the coming decades.

     

Enhancing capacity for freshwater conservation at the genetic level: a demonstration using three stream macroinvertebrates

1. Species diversity is declining more rapidly in freshwater ecosystems than in any other, but the consequences for genetic diversity, and hence evolutionary potential, are poorly understood. In part this reflects limited use and development of modern molecular tools and genetic approaches to address conservation questions in rivers, lakes and wetlands. As widespread, diverse and functionally important organisms, freshwater macroinvertebrates are ideal candidates for genetic approaches to reveal, for example, the conservation consequences of demographic histories and past disturbances. However, the availability of microsatellite markers for this group is very limited.
2. Using next generation sequencing, microsatellite markers were developed for Isoperla grammatica (Poda, 1761), Amphinemura sulcicollis (Stephens, 1836) and Baetis rhodani (Pictet, 1843) to enable conservation genetic investigations of these widespread invertebrate species. Fifty‐two robust microsatellite loci were developed (18, 21 and 13 per species), all with high levels of allelic diversity (7–27, 3–16, 5–13 alleles per loci, respectively).
3. These tools will allow assessment of genetic structure, dispersal and demographic resilience in these model species as a function of environmental change and variation, thereby aiding freshwater monitoring and conservation. The authors urge further capacity building to support genetic applications to the conservation biology of other aquatic organisms.

Copyright © 2016 John Wiley & Sons, Ltd.     

WSSV envelope protein VP51B links structural protein complexes and may mediate virus infection

White spot syndrome virus (WSSV), an enveloped double‐stranded DNA virus, is the causative agent of a disease that has led to severe mortalities of cultured shrimps in Taiwan and many other countries. In the previous study, Penaeus monodon chitin‐binding protein (CBP) and glucose transporter 1 (Glut1), two cell membrane proteins, were found to at least interact with other 10 WSSV envelope proteins including VP51B. These envelope proteins might form a protein complex. According to the known information, VP51B was used to identify its role in the protein complex. Western blotting of the intact viral particles and fractionation of the viral components confirmed that VP51B is one of WSSV envelope proteins. In this study, the protein–protein interaction between VP51B and other WSSV envelope proteins was identified by far‐western blot experiment and VP51B was found to interact with VP24, VP31, VP32, VP39B and VP41A. Furthermore, the in vivo neutralization experiment using recombinant VP51B plus with VP39B showed the best inhibition. These data indicate that VP51B participates in the WSSV protein complex and plays an important role in WSSV infection.     

Impact of sampling and storage technique,and duration of storage,on the composition of fresh grass when analysed using near‐infrared reflectance spectroscopy

The objective of this study was to examine the effect of sampling technique (pluck or cut), storage duration (immediate analysis, 24‐h or 48‐h), storage temperature (ambient or chilled) and storage conditions (air present, air excluded or breathable) on the composition of fresh grass sampled from a sward managed to simulate grazing. Treatments were repeated across four sampling dates, with grass samples stored in grip seal bags prior to analysis using near‐infrared reflectance spectroscopy. Grass sampled by ‘pluck’ had a higher crude protein and ME content, and a lower acid detergent fibre (ADF) content, compared to that sampled by ‘cut’. Grass stored for 48 h had a lower water soluble carbohydrate (WSC) and ME content and a higher ADF content than for immediate analysis. Samples stored for 24 h did not differ from immediate analysis. Grass stored at ambient temperature had a lower WSC and ME content compared to immediate analysis. Grass stored under ‘breathable’ conditions had a lower ME content and higher ADF content than immediate analysis or samples stored with air present or air excluded. It is recommended that grass for analysis should be sampled by cutting, stored chilled (4°C) in a sealed bag to minimize exposure to oxygen and analysed within 24 h of harvest.     

terraGIS – a web GIS for delivery of digital soil maps in cotton‐growing areas of Australia

Effective management of soil requires the spatial distribution of its various physical, chemical and hydrological properties. This is because properties, for example clay content, determine the ability of soil to hold cations and retain water. However, data acquisition is labour intensive and time‐consuming. To add value to the limited soil data, remote sensing (e.g. airborne gamma‐ray spectrometry) and proximal sensing, such as electromagnetic (EM) induction, are being used as ancillary data. Here, we provide examples of developing Digital Soil Maps (DSM) of soil physical, chemical and hydrological properties, for seven cotton‐growing areas of southeastern Australia, by coupling soil data with remote and proximal sensed ancillary data. A greater challenge is how to get these DSM to a stakeholder in a way that is useful for practical soil use and management. This study describes how we facilitate access to the DSMs, using a simple‐to‐use web GIS platform, called terraGIS. The platform is underpinned by Google Maps API, which is an open‐source development environment for building spatially enabled Internet applications. In conclusion, we consider that terraGIS and the supporting information, available on the sister web page ( http://www.terragis.bees.unsw.edu.au/ ), allow easy access to explanation of DSM of soil properties, which are relevant to cotton growers, farm managers, consultants, extension staff, researchers, state and federal government agency personnel and policy analysts. Future work should be aimed at developing error budget maps to identify where additional soil and/or ancillary data is required to improve the accuracy of the DSMs.     

Otolith chemistry indicates walleye movement and entrainment in a large serial reservoir system

Understanding fish movement in impounded river systems is important for fisheries management. Otolith chemistry was used to examine walleye Sander vitreus (Mitchill) intra‐ and inter‐reservoir movement in four Missouri River impoundments. Age‐0 individuals were reclassified with 75%–93% accuracy to known natal sites, allowing for reliable evaluation of movement patterns of age‐1 and older fish. Nearly half of walleye occupied the same location annually (i.e. site residency) between 2009 and 2010. In 2011, during the largest flood on record since 1898, downstream movement (49% of age‐1 and older fish) exceeded upstream movement (7%) and site residency (33%) across the study area. After the flood, most walleye moved downstream within reservoirs (45%) or were site residents (37%). Entrainment occurred most frequently during the flood year and was proportionally greatest in downstream reservoirs. Otolith chemistry is useful for understanding walleye movement and entrainment and is a tool for fisheries management with applications such as informing reservoir water releases, harvest regulations and habitat protection and rehabilitation within and outside the Missouri River reservoir system.