Effects of stocking density, periphyton substrate and supplemental feed on biological processes affecting water quality in earthen tilapia–prawn polyculture ponds     

Mohammed Sharif Uddin  Ana Milsten  Mohammed Ekram Azim  Mohammed Abdul Wahab  Marc Verdegem  & Johan Verreth 《Aquaculture Research》2008,39(12):1243-1257

The technical and economic potentials of tilapia, Oreochromis niloticus (L.), and giant river prawn, Macrobrachium rosenbergii (de Man), polyculture in periphyton-based systems are under investigation in an extensive research programme. This article is a combined analysis of data from four experiments exploring the effects of periphyton, fish, prawn and feed on water quality. Factor analysis and ancova models applied to the combined dataset allowed to identify the underlying ecological processes governing the system, and construct conceptual graphic models of the periphyton–environment relationships observed. With the first factor, variability in water quality was due to autotrophic (photosynthesis and nutrient uptake) and heterotrophic (respiration and decomposition) processes affecting water quality in opposite directions. With the second factor, variability was related to decomposition on the bottom and nutrient release into the water column, algae production and sedimentation. The analysis of the relationships between both factors and the growth rates of tilapia and prawn in the different systems allowed a better understanding of the functioning of tilapia–prawn ponds, and indicates that their joint culture is technically feasible and economically viable. Therefore, this technology is recommended for poverty alleviation and nutritional security in rural Bangladesh as well as in other countries of the region.  相似文献   

Effect of dietary carbohydrate to lipid ratio on performance of Nile tilapia and enhancement of natural food in pond aquaculture     

Kazi A. Kabir  Marc C. J. Verdegem  Johan A. J. Verreth  Michael J. Phillips  Johan W. Schrama 《Aquaculture Research》2020,51(5):1942-1954

This study tested the effect of two diets differing in carbohydrate to lipid (CHO:LIP) ratio (4.7 vs. 19.5 g/g) on the contribution of natural food and the total fish production in tilapia ponds. Eight ponds, each divided into three equally sized compartments, were assigned to one of the two diets, which differed in CHO:LIP ratio but had the same digestible protein to digestible energy (DP:DE) ratio (15.5 and 15.6 g/MJ). Ponds were fed equal amounts of crude protein. Three feeding levels (no, low and high) were nested in each pond in a split plot design. Average body weight of fish at stocking was 90 g, and the duration of the experiment was 42 days. Increasing the CHO:LIP ratio had no impact on tilapia production. However, the feeding level influenced both biomass gain, specific growth rate and survival. The apparent digestibility coefficient (ADC) for fat and carbohydrate was influenced by dietary CHO:LIP ratio but ADC for energy was unaffected. Proximate analysis of fish body composition showed no effect of diet except for levels of ash. Diet had no effect on the organic matter composition of the faeces, and the contribution of natural food to fish nitrogen gain. Therefore, we postulate that changing the dietary non‐protein energy source from lipid to carbohydrate does not have any impact on tilapia culture in semi‐intensive ponds.  相似文献   

The effect of dietary protein source (fishmeal vs. plant protein) and non‐starch polysaccharide level on fat digestibility and faecal bile acid loss in rainbow trout (Oncorhynchus mykiss)     

Thomas W. O. Staessen  Marc C. J. Verdegem  Paraskevi Koletsi  Johan W. Schrama 《Aquaculture Research》2020,51(3):1170-1181

This study investigated in rainbow trout (Oncorhynchus mykiss) if diet composition and feeding level affect faecal bile acid loss, and whether this reflects on the apparent digestibility coefficient (ADC) of fat. Six diets were formulated with either fishmeal or plant protein as main protein source. This created a contrast in the supply of bile acids, the bile acid precursor cholesterol, taurine and the taurine precursors (methionine + cysteine) involved in bile acid conjugation. For both protein sources, three diets were formulated with increasing inclusion of a non‐starch polysaccharide (NSP)‐rich ingredient mixture (0.0, 82.0 and 164.2 g/kg diet). This aimed at enhancing faecal bile acid loss. Fish were fed both restrictively (1.2% BW/day) and to satiation. A similar fat ADC was found when substituting fishmeal with a plant protein mixture, suggesting that the lower content of bile acids, cholesterol, taurine, methionine and cysteine in the plant‐based diets did not limit fat digestion. Faecal bile acid loss increased alongside dietary NSP level, however, only during satiation feeding and most strongly for fish fed the fishmeal‐based diets. Enhanced faecal bile acid loss was not caused by NSP‐bile acid binding/entrapment, but by an increase in faeces production. During satiation feeding, fat ADC negatively correlated with faecal bile acid loss. From this it is concluded that bile acid availability/synthesis can become limiting for fat digestion in rainbow trout under conditions that enhance faecal bile acid loss (i.e. dietary NSP level and feeding level).  相似文献   

Digital camera monitoring of recreational fishing effort: Applications and challenges     

Bruce W. Hartill  Stephen M. Taylor  Krystle Keller  Marc Simon Weltersbach 《Fish and Fisheries》2020,21(1):204-215

The growing awareness of the impact that recreational fishers can have on fish stocks has highlighted the paucity of information used to inform their management. Most of the available information on the scale and nature of recreational catch and effort has come from intermittent and labour‐intensive surveys that provide fragmented insights into often highly variable fisheries. Digital cameras offer a more cost‐effective means of continuously monitoring trends in recreational fishing effort, and it is surprising that greater use of this approach has not been made to date given its widespread use in other contexts. We share lessons learnt from four early adopter studies in New Zealand, Australia and Germany, where digital cameras have been used to monitor recreational fishing effort. Many of the challenges that we have encountered and overcome were initially unforeseen, and we suggest solutions and strategies to address these issues. We conclude that all aspects of a camera‐based monitoring system should be considered from the outset, to optimize the utility and value of the information they provide over the long term. Aspects to consider include the location and configuration of a camera system, ensuring service continuity, image quality, data storage, image interpretation and ultimately the analysis of any data collected. Robustly designed digital camera monitoring systems can be used to gain greater insight into recreational fishery dynamics, leading to more informed, responsive and effective fisheries management.  相似文献   

Bacillimidazoles A−F,Imidazolium-Containing Compounds Isolated from a Marine Bacillus     

Jia-Xuan Yan  Qihao Wu  Eric J. N. Helfrich  Marc G. Chevrette  Doug R. Braun  Heino Heyman  Gene E. Ananiev  Scott R. Rajski  Cameron R. Currie  Jon Clardy  Tim S. Bugni 《Marine drugs》2022,20(1)

Chemical investigations of a marine sponge-associated Bacillus revealed six new imidazolium-containing compounds, bacillimidazoles A–F (1–6). Previous reports of related imidazolium-containing natural products are rare. Initially unveiled by timsTOF (trapped ion mobility spectrometry) MS data, extensive HRMS and 1D and 2D NMR analyses enabled the structural elucidation of 1–6. In addition, a plausible biosynthetic pathway to bacillimidazoles is proposed based on isotopic labeling experiments and invokes the highly reactive glycolytic adduct 2,3-butanedione. Combined, the results of structure elucidation efforts, isotopic labeling studies and bioinformatics suggest that 1–6 result from a fascinating intersection of primary and secondary metabolic pathways in Bacillus sp. WMMC1349. Antimicrobial assays revealed that, of 1–6, only compound six displayed discernible antibacterial activity, despite the close structural similarities shared by all six natural products.  相似文献   

Regional Differences in the Relation Between Monthly Precipitation and Bulk Concentration in France (Renecofor)     

Ulrich  Erwin  Lelong  Nicolas  Lanier  Marc  Schneider  Arnaud 《Water, air, and soil pollution》1998,102(3-4):239-257

Bulk precipitation was sampled weekly from 1993 to 1994 at 27 sites, covering the whole country. In this paper the relations between decreasing concentrations of 4-weekly mean weighted samples with increasing 4-weekly precipitation are studied using two types of equations: (i) y = a+b/x; (ii) y+1= ax^b, where y = concentration of an ion and x = 4-weekly precipitation quantity. Relationships were studied for the major ions. H⁺ did not show any relationship with the rainfall amount. From the 216 regressions (27 sites × 8 ions) for all the other ions, 55.6% showed a good fit (r equal or above 0.6) and 16.2% a very good fit (r equal or above 0.85). Good fits were found for 85% of the regressions for N-NO₃ ^-, 81% for S-SO₄ ^2-, 63% for Ca²⁺, 59% for K⁺, 55% for N-NH₄ ⁺, 37% for Mg²⁺, 33% for Cl^- and 29% for Na⁺. The comparison between sites for the same ions showed: (i) the ranking of the sites after the regressions from lower to higher concentration levels does not necessarily correspond to the ranking of the sites bi-annual mean weighted concentrations; (ii) sites showed similar behaviour for certain ions for which an explanation could be found, based on local or regional emission characteristics or air mass influences, and for others this was not possible; (iii) for certain ions and pairs of sites, comparable annual precipitation led to comparable behaviour, for others precipitation was not an explanatory factor at all, (iv) local and regional influences seem to have a much greater impact on decreasing concentrations than the gradient from the Atlantic coast to the eastern French border.  相似文献   

The interrelationships of stride lengths and stride times to velocities of galloping horses     

Marc H. Ratzlaff DVM  PhD  Roger M. Shindell MS  Karl K. White DVM 《Journal of Equine Veterinary Science》1985,5(5):279-283

Side view slow motion movies of galloping horses were taken and analyzed to determine horse velocity, limb velocity, stride length, stride time, and the swing and support timesof the stride. Multivariate statistical methods were used to evaluate the interrelationships of theseparameters. A linear relationship between horse velocity and limb velocity was observed; however, two groups could be distinguished within the trials. In one group, in which the horses were galloping normally, a one-to-one relationship of limb velocity to horse velocity was noted. In the other group, in which the majority of the horses were either lame or restrained by the rider, limb velocities were higher than horse velocities.In general, as horse velocity increased, stride length increased and stride time decreased due to decreases in both the swing and support times of the stride. Increases in stride length contributed more to increases in horse velocity than changes in either swing or support times. Changes in stride length had the greatest effect upon the velocities of those horses that were either lame or restrained by the rider, while the effects of changes in swing and support times contributed relatively more to changes in velocities of the horses which were galloping normally.This study suggests that in lame horses, limb velocity is proportionally greater than horse velocity due to decreases in stride length and stride time.  相似文献   

Feeding Relations of Silver Barb Barbodes gonionotus (Bleeker) with Major Indian and Common Carp and Its Effect on Fish Production in a Polyculture System     

M. Ekram  Azim  M. Abdul  Wahab Abu H. M.  Kamal Zoarder F.  Ahmed Marc C. J.  Verdegem 《Journal of the World Aquaculture Society》2004,35(1):100-108

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Gaby: a computer-based decision support system for integrated pest management in Dutch apple orchards     

Ernst Van Den Ende  Leo Blommers  Marc Trapman 《Integrated Pest Management Reviews》1996,1(3):147-162

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COMPARISON OF SPIN ECHO, GRADIENT ECHO AND FAT SATURATION MAGNETIC RESONANCE IMAGING SEQUENCES FOR IMAGING THE CANINE ELBOW     

Frédéric R.  Snaps  DVM  DScV  CERTVR  Jimmy H.  Saunders  DVM  CERTVR  Richard D.  ParkDMV  PHD  Bénédicte  DaenenMD  Marc H.  BalligandDVM  DScV  CSAO  Robert F.  DondelingerMD 《Veterinary radiology & ultrasound》1998,39(6):518-523

Two comparison studies were performed. In the first conventional spin-echo (T1- and T2-weighted) sequences and a three-dimensional (3-D Fourier transform [3DFT]) echo gradient fast-imaging sequence were compared for imaging the canine normal elbow joint. In all three sequences, there was an isointense signal of the articular cartilage and a hyposignal of the subchondral bone, as compared with the muscles. The medial coronoid process of the ulna was clearly seen on the dorsal plane images, it appeared with a homogenous low-intensity signal. Its articulation with the radius was clearly outlined. In a second study, the 3DFT echo gradient fast-imaging sequence was compared to a fat saturation sequence on normal shoulder and elbow joints. Elbows were imaged with and without injection of saline, in an attmept to show the opposing cartilaginous articular surfaces. This distinction was possible in the shoulder joint but not in the elbow because of insufficient spatial resolution. On the three MRI sequences compared, gradient echo fast imaging with steady-state precession (GE FISP) sequence was found to be the most suitable for imaging the canine elbow joint.  相似文献