The impact of bait-pumping on populations of the ghost shrimp Trypaea australiensis Dana (Decapoda: Callianassidae) and the sediment environment

This study investigated the relative effects of bait-pumping and the associated disturbance of mudflats on populations of the ghost shrimp Trypaea australiensis and various sediment properties at Coronet Bay, Western Port, southern Australia. The experiment followed a BACI design, with 3 months of sampling before and after the simulated impact. Control plots were left undisturbed while two disturbance treatments (impact and procedural control) were bait-pumped. Ghost shrimp were removed from the impact plots, whereas ghost shrimp were allowed to re-burrow in the procedural control plots. The purpose of the procedural control was to test for the effect of the disturbance associated with bait-pumping. Initial destruction of burrows and compaction of sediment due to bait-pumping and trampling of the mudflat, reduced sediment porosity and created more reducing conditions to depths of 20 cm. The proportion of small particles (<250 μm) and abundance of benthic microalgae increased in surface sediments, whereas organic carbon content decreased. Ghost shrimp density decreased considerably and was slow to recover over the experimental period. Both disturbance treatments responded similarly indicating that the mudflat disturbance associated with bait-pumping was the major cause of the effects observed.     

食物条件对日本蟳幼体存活与变态的影响

This paper studied the effects of different kind and density of baits and different starvation duration on Charybdis japonica larvae. The results showed that the preferable baits of zoaea-1 were Chaetoceros sp. and Isochysisgalbana, and their proper feeding density were 20 × 10^4 cell· ml^-1. The preferable bait of the larvae after zoaea-1 was Artemia salina nauplius, and its proper feeding density for zoaea-2 and zoaea-3 was 2 - 3 ind· ml^-1. The point of no-return for zoaea-1 of Charybdisjapoptica was about 66 hours. 18 hours starvation did not affect the growth of the larvae, but their livability would be decreased, and their metamorphism would be suspended along with the starvation duration.     

DEV-NP基因酵母双杂交诱饵载体的构建及自激活检测

为构建鸭肠炎病毒(DEV)核衣壳蛋白(NP)基因酵母双杂交诱饵载体,采用PCR技术扩增出DEV-NP基因,克隆至酵母双杂交诱饵质粒pGBKT7中,以PCR检测、限制性酶切和序列测定等方法进行鉴定;然后采用PEG/LiA.法将阳性质粒pGBKT7-NP转化酵母Y2HGold,在不同营养缺失型培养基进行自激活检测,结果显示,经PCR检测和EcoR I/BamH I双酶切,可见到与预期相一致的目的片段;测序表明该片段含DEV NP基因全部序列;转化Y2HGold酵母菌后,在SD/-Trp/X-a-Gal 固体培养基上长出蓝色菌落,而在SD/-Trp/X-a-GaUAbA固体培养基上未见有菌落生长.无自激活作用的诱饵载体pGBKT7NP的成功构建,为DEV NP宿主结合蛋白的筛选莫定了基础.     

Complementary video and acoustic recordings of foraging by two pest species of slugs on non-toxic and molluscicidal baits

The effects of adding the molluscicides methiocarb and metaldehyde to pelleted foods on the encounter, acceptance, feeding and post-meal stages of the foraging sequence of the slugs Deroceras reticulatum and Arion distinctus have been studied using two complementary laboratory techniques - video and acoustic recordings. Whereas non-feeding slugs encountered wheat grains at random, slugs which fed on wheat grains or pellets encountered them more frequently because of changes in locomotor pattern and olfactory attraction. Slugs would almost always feed on the first pellet they found, regardless of the presence or absence of molluscicide: thereafter they fed on only one pellet in every four encountered. Far fewer slugs accepted wheat grains. Slugs ate much less from pellets containing molluscicide, and meals were more irregular. The relative amounts of non-toxic pellets of various types which were eaten gave no indication of the relative amounts eaten when molluscicide was added. Meal length did not correlate well with meal size on different pellet types because softer pellets were eaten faster. Most Deroceras fed several times on non-toxic pellets or pellets containing methiocarb, although subsequent meals were shorter than the first meal. Most returned to shelters by dawn. In contrast, metaldehydefed slugs were rapidly immobilised; they seldom fed again, moved little, and few regained shelter. Arion were also inhibited after methiocarb meals but Deroceras were not. Arion distinctus moved less, ate less during a meal, and had fewer meals on nontoxic baits than Deroceras reticulatum.     

Behavioral responses to food odor in juvenile marine fish: Acuity varies with species and fish length

This study tested the hypothesis that acuity of behavioral responses to food odor in three commercially important species of marine fish would increase as juvenile length increased. Swimming activity among two size groups of fish was measured in the presence of a series of squid extract dilutions. Increased swimming activity in juvenile Pacific halibut Hippoglossus stenolepis Schmidt, walleye pollock Theragra chalcogramma Pallas, and sablefish Anoplopoma fimbria Pallas was stimulated above threshold concentrations of squid extract, expressed as dilution from full strength. Maximum chemosensory acuity was observed in smaller (8-14 cm total length, TL) Pacific halibut and walleye pollock, while larger sablefish (15-23 cm TL) continued to develop acuity. Response thresholds were highest (10^− 3 dilution) in Pacific halibut, at intermediate levels (10^− 4-10^− 6 dilution) in walleye pollock and smaller sablefish and reached the lowest levels (10^− 13 dilution) in larger sablefish. The widely held view that dissolved free amino acids (DFAA) are the primary chemosensory stimulants for fish food searching may not be valid for sablefish, as they detected squid extract at dilutions containing DFAA that appeared to be far below ambient sea water DFAA concentrations.     

原绿球藻的营养组分分析及饵料效果研究

为探究原绿球藻(Prochlorococcus marinus)的应用, 采用生化分析测定了其营养组分, 并进行了投喂蒙古裸腹溞和褶皱臂尾轮虫饵料效果试验. 结果显示: 原绿球藻干品中含粗蛋白42.32%, 粗脂肪11.47%, 碳水化合物15.11%和灰分17.48%. 含16种氨基酸, 总氨基酸含量为35.88 mg/g, 包括必需氨基酸8种 (占总氨基酸的37.54%); 粗脂肪中含13种脂肪酸, 其中不饱和脂肪酸8种(占粗脂肪总重的58.26%), 单不饱和脂肪酸(54.12%)含量较高, 而多不饱和脂肪酸含量较低(4.14%). 用原绿球藻投喂蒙古裸腹溞, 藻最佳浓度是400104 cells/mL, 溞世代净生殖率达4.33, 内禀增长率为0.23. 蒙古裸腹溞在用原绿球藻强化之后, 二十碳五烯酸(EPA)能有效富集, 浓度可达6.69%. 不同密度的原绿球藻饲喂对褶皱臂尾轮虫抱卵数和抱卵率均影响显著. 投喂藻密度在48-96h阶段以600104 cells/mL为佳, 而96-144h以400104 cells/mL为佳. 通过研究发现, 原绿球藻具有较好的营养价值和饵料效果, 但在蒙古裸腹溞和褶皱臂尾轮虫培养中, 仍建议与其他藻混合投喂.       

The effect of competing carnivores on the feeding behaviour of leopards (Panthera pardus) in an African savanna

Knowledge of competition dynamics among Africa’s large carnivores is important for conservation. However, investigating carnivore behaviour in the field can be challenging especially for species that are difficult to access. Methods that enable remote collection of data provide a means of recording natural behaviour and are therefore useful for studying elusive species such as leopards (Panthera pardus). Camera traps and Global Positioning System (GPS) collars are powerful tools often used independently to study animal behaviour but where their data are combined, the interpretation of a species’ behaviours is improved. In this study we used data from baited camera trap stations to investigate the feeding habits of leopards at Malilangwe Wildlife Reserve, Zimbabwe. We investigated the influence of spotted hyenas, lions and other competing leopards on the feeding duration of leopards using Generalized Linear Mixed Effects Modelling. To test the influence of competing predators on resting distances from bait sites, eight leopards were fitted with GPS collars. Results showed that leopards spent the shortest time feeding on the baits in the presence of competing male leopards compared to other predators while lion presence caused animals to rest farthest from bait sites. Interaction analysis indicated that small‐bodied leopards spent significantly shorter durations feeding when spotted hyenas were present. Our findings demonstrate that competition from guild carnivores has negative impacts on the food intake of leopards, which may have implications for fitness and survival. This study provides a snapshot of the competition dynamics at bait sites which may give insight to ecosystem level interactions among large carnivores in savanna ecosystems.     

食物条件对日本幼体存活与变态的影响

This paper studied the effects of different kind and density of baits and different starvation duration on Charybdis japonica larvae. The results showed that the preferable baits of zoaea-1 were Chaetoceros sp. and Isochrysis galbana,and their proper feeding density were 20×10⁴ cell·ml^-1.The preferable bait of the larvae after zoaea-1 was Artemia salina nauplius, and its proper feeding density for zoaea-2 and zoaea-3 was 2～3 ind·ml^-1.The point of no-return for zoaea-1 of Charybdis japonica was about 66 hours. 18 hours starvation did not affect the growth of the larvae, but their livability would be decreased, and their metamorphism would be suspended along with the starvation duration.     

Using a baited camera to assess relative abundance of juvenile Pacific cod: Field and laboratory trials

Juvenile fishes are sometimes difficult to survey because they occur in a variety of structurally complex habitats that are not readily sampled with traditional trawl or seine gear. Laboratory experiments and field sampling were conducted to determine whether a baited-camera system could be used effectively to survey age-0 gadids. Pacific cod (Gadus macrocephalus Tilesius), saffron cod (Eleginus gracilis Tilesius), and walleye pollock (Theragra chalcogramma Pallas) all responded to bait bags presented in the laboratory, with increased general activity and approaches to the bait. Pacific cod responded most strongly, and remained in close proximity to the bait bag. In nearshore habitats of Kodiak, Alaska, age-0 gadids (mostly Pacific cod) were quickly attracted to a baited-camera system. Arrival rates stabilized within 15-min, and several metrics for Pacific cod abundance taken from the video records were closely correlated with the numbers collected in seine hauls. Highest correlations occurred with the total number of fish arriving in camera view during 15-min sets (NFA₁₅) and with the overall maximum number of fish observed at one time during the sets (MaxN_O). The time for first arrival of fish in view (TFA) was not correlated significantly with the numbers of fish in seine collections. NFA₁₅ was also useful for age-1+ saffron cod. Occasionally, the presence of large fish had a negative effect on assessments of age-0 fish, but the impact was important only when the large fish were present continuously. The baited-camera system performed equally well in seagrass, kelp and open habitats, and can be used to rapidly assess the relative abundance of Pacific cod and selected other species in a wide range of habitats in shallow and deep water.     

Effect of Bait Substrate and Formulation on Infection of Grasshopper Nymphs by Beauveria bassiana

The effects of two formulations (oil and water) and two bait substrates (lettuce and bran) on infection of grasshopper nymphs (Melanoplus sanguinipes) by Beauveria bassiana were investigated. More nymphs died of mycosis after they had ingested substrates inoculated with conidia in oil than in water, but there was no difference between the lettuce and bran substrates. Of the conidia recovered in frass, most (95%) were recovered within 24 h of ingestion of the lettuce and bran substrates by nymphs. Significantly more conidia averaged over time were recovered in frass from the water than from the oil formulation. A higher incidence (33-82%) and more rapid onset of mycosis was observed in nymphs that were surface-sterilized before ingestion, compared with those surface-sterilized after ingestion of lettuce and bran substrates inoculated with B. bassiana in both formulations. A similar trend was observed in nymphs receiving the sterilization treatment before, rather than after, ingestion of wheat leaves sprayed with conidia in oil or water. Numerous conidia were observed on the heads, thoraxes and abdomens of nymphs that ingested treated lettuce or bran. Modest numbers of conidia were also recovered from the surfaces of nymphs, but no differences were observed between formulations or substrates. However, when nymphs ingested lettuce disks treated with fluorescent dye in either oil or water, more dye was observed on nymphs with the oil formulation. This laboratory study demonstrates that grasshopper nymphs are highly susceptible to infection by conidia formulated on bait substrates, and that the efficacy of the bait relies on the extent to which nymphs become surface-contaminated during ingestion.