Stepwise function of natural growth for Scylla serrata in East Africa: a valuable tool for assessing growth of mud crabs in aquaculture

Predicting growth is critical in aquaculture, but models of growth are largely missing for mud crab species. Here, we present the first model of natural growth in juvenile and adult mud crabs Scylla serrata from East Africa using a stepwise growth function based on data on intermoult periods and growth at moult from field mark‐recapture, pond and laboratory studies. The results showed a sigmoid growth pattern in carapace width and suggest that S. serrata in East Africa will reach 300 g and sexual maturity ~9.9 months after settlement, and a commercial size of 500 g after 12.4 months. Analyses of the literature identified several issues with the common praxis to compare standard growth measures between aquaculture studies with different initial size or growing periods. Using the new growth function to estimate the proportional difference between modelled and obtained growth as an alternative method, we show that growth rates of S. serrata cultured in cage systems, which are dominant in East Africa, was <40% of the estimated natural growth and growth obtained in pond systems. The analysis also indicated that growth rates of S. serrata in Southeast Asia was over 50% higher compared with similar culture systems in East Africa, and that different species of mud crabs had large differences in growth rates. This study shows that growth in the present mud crab aquaculture systems in East Africa is below their expected potential. Further work is needed to identify the factors behind this observation.     

Comparison of antioxidant potency of commonly consumed polyphenol-rich beverages in the United States

A number of different beverage products claim to have antioxidant potency due to their perceived high content of polyphenols. Basic and applied research indicates that pomegranate juice (PJ), produced from the Wonderful variety of Punica granatum fruits, has strong antioxidant activity and related health benefits. Although consumers are familiar with the concept of free radicals and antioxidants, they are often misled by claims of superior antioxidant activity of different beverages, which are usually based only on testing of a limited spectrum of antioxidant activities. There is no available direct comparison of PJ's antioxidant activity to those of other widely available polyphenol-rich beverage products using a comprehensive variety of antioxidant tests. The present study applied (1) four tests of antioxidant potency [Trolox equivalent antioxidant capacity (TEAC), total oxygen radical absorbance capacity (ORAC), free radical scavenging capacity by 2,2-diphenyl-1-picrylhydrazyl (DPPH), and ferric reducing antioxidant power (FRAP)]; (2) a test of antioxidant functionality, that is, inhibition of low-density lipoprotein (LDL) oxidation by peroxides and malondialdehyde methods; and (3) evaluation of the total polyphenol content [by gallic acid equivalents (GAEs)] of polyphenol-rich beverages in the marketplace. The beverages included several different brands as follows: apple juice (3), a?aí juice (3), black cherry juice (3), blueberry juice (3), cranberry juice (3), Concord grape juice (3), orange juice (3), red wines (3), iced tea beverages (10) [black tea (3), green tea (4), white tea (3)], and a major PJ available in the U.S. market. An overall antioxidant potency composite index was calculated by assigning each test equal weight. PJ had the greatest antioxidant potency composite index among the beverages tested and was at least 20% greater than any of the other beverages tested. Antioxidant potency, ability to inhibit LDL oxidation, and total polyphenol content were consistent in classifying the antioxidant capacity of the polyphenol-rich beverages in the following order: PJ>red wine>Concord grape juice>blueberry juice>black cherry juice, a?aí juice, cranberry juice>orange juice, iced tea beverages, apple juice. Although in vitro antioxidant potency does not prove in vivo biological activity, there is also consistent clinical evidence of antioxidant potency for the most potent beverages including both PJ and red wine.     

Screening of foods containing proanthocyanidins and their structural characterization using LC-MS/MS and thiolytic degradation

A normal-phase HPLC-MS/MS method was applied to screen for proanthocyanidins in 88 different kinds of foods. Thirty-nine foods were found to contain proanthocyanidins. These foods include 19 kinds of fruits, eight cereals/beans, seven nuts, two beverages, two spices, and one vegetable. Twenty-five kinds of foods were found to contain both oligomeric (DP 10), and the other 14 foods contained only oligomers. Procyanidins with B-type linkages were detected as the only components in 21 foods and also as principal components in the others. Propelargonidins were identified in pinto bean, raspberry, strawberry, and almond, etc. Plum, avocado, peanut, curry, and cinnamon were identified as potential sources of A-type proanthocyanidins in addition to cranberry. Thiolytic degradation and MS/MS analyses indicated that the A-type linkages are present as a terminal unit in plum or between the extension units in curry, cinnamon, and avocado, whereas A-type linkages exist at both positions in cranberry and peanut.     

Changes in the herbicide sensitivity and competitive ability of Abutilon theophrasti over 28 years: Implications for hormesis and weed evolution

BACKGROUND

The potential of weed species to respond to selection forces affecting the evolution of weedy traits such as competitive ability is poorly understood. This research characterized evolutionary growth changes in a single Abutilon theophrasti Medik. population comparing multiple generations collected from 1988 to 2016. A competition study was performed to understand changes in competitive ability, and a herbicide dose–response study was carried out to assess changes in sensitivity to acetolactate synthase-inhibiting herbicides and glyphosate over time.

RESULTS

When grown in monoculture, A. theophrasti biomass production per plant increased steadily across year-lines while leaf number decreased. In replacement experiments, A. theophrasti plants from newer year-lines were more competitive and produced more biomass and leaf area than the oldest year-line. No clear differences in sensitivity to imazamox were observed among year-lines. However, starting in 1995, this A. theophrasti population exhibited a progressive increase in growth in response to a sublethal dose of glyphosate (52 g a.e. ha⁻¹), with the 2009 and 2016 year-lines having more than 50% higher biomass than the nontreated control.

CONCLUSION

This study demonstrates that weeds can rapidly evolve increased competitive ability. Furthermore, the results indicate the possibility of changes in glyphosate hormesis over time. These results highlight the importance of the role that rapid (i.e., subdecadal) evolution of growth traits might have on the sustainability of weed management strategies. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Direct analysis of pesticide residues in olive oil by on-line reversed phase liquid chromatography-gas chromatography using an automated through oven transfer adsorption desorption (TOTAD) interface

A fully automated on-line reversed phase liquid chromatography-gas chromatography system is described. The system uses a prototype of the automated through oven transfer adsorption desorption interface. The system is demonstrated by presenting a new rapid method for the determination of pesticide residue in olive oil, which is injected directly with no sample pretreatment step other than filtration. Methanol:water is used as the eluent in the LC preseparation step, while the LC fraction containing the pesticide is automatically transferred to the gas chromatograph. Detection limits of pesticides varied from 0.18 to 0.44 mg/L when a flame ionization detector was used. As an example, relative standard deviation and linear calibration are presented for terbutryne.     

Human behaviour: the key source of uncertainty in fisheries management

There is broad consensus that the main problem facing fisheries globally is too many boats chasing too few fish. Unfortunately it is also possible to argue that there are too many proposed solutions and not enough practical answers to improving fisheries management. There is a deepening divide between those who propose alternative regulatory controls on fishers, including establishing large areas permanently closed to fishing, and those who argue for better alignment of incentives combined with broad participation of resource users in fishery management decisions (in simple terms, between top down and bottom up systems of governance). However despite the choice of policy instruments used, a consistent outcome is that resource users behave in a manner that is often unintended by the designers of the management system. Hence whilst uncertainty is broadly recognized as a pervasive feature of fisheries management, to date most of the attention has focussed on only part of that uncertainty – scientific uncertainty about the status of exploited resources. The effect of uncertainty generated on the human side of fisheries science and management has received much less attention. However, the uncertainty generated by unexpected resource user behaviour is critical as it has unplanned consequences and leads to unintended management outcomes. Using empirical evidence of unexpected resource user behaviour and reviewing current responses to unexpected management outcomes, we identify different approaches that both improve prediction of human behaviour in fisheries systems and identify management measures that are more robust to these sources of uncertainty. However, unless the micro scale drivers of human behaviour that contribute to macro scale implementation uncertainty are communicated effectively to managers and considered more regularly and in greater depth, unanticipated responses to management actions will continue to undermine management systems and threaten the sustainability of fisheries.     

Food sources,digestive efficiency and resource allocation in the sea cucumber Holothuria forskali (Echinodermata: Holothuroidea): Insights from pigments and fatty acids

Various research projects in Europe and North Africa have recently intended to breed temperate holothurians to alleviate fishing pressure on natural populations. However, to date little is known about the nutritional requirements of East Atlantic and Mediterranean species. In this study, we propose a “natural population”‐oriented approach to characterize food sources, digestive efficiency and resources allocation based on the composition of pigments and fatty acids (FA) in gut contents and tissues (muscles, gonads and digestive tract walls) of wild individuals of the species Holothuria (Panningothuria) forskali (Delle Chiaje, 1823) sampled in Brittany (France). Our study reveals that neither green nor red algae enter the diet of H. forskali in spring and that the only fresh vegetal material found in gut contents is brown algae (very likely diatoms). The high nutritional quality of gut contents however contrasts with the detrital nature of the ingested food sources, suggesting that a trophic upgrading of organic matter occurs before digestion. In addition, unusual FA (i.e. only present in a few groups of living species) such as long‐chain monounsaturated FA (especially the FA 23:1ω9) were found in large proportions in muscles and gonad and their effect on sea cucumber fitness needs further investigation.