Cetacean occurrence,habitat preferences and potential for cetacean–fishery interactions in Iberian Atlantic waters: results from cooperative research involving local stakeholders

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Fumigant toxicity of essential oils against Sitophilus zeamais (Motschulsky) (Coleoptera: Curculionidae): a systematic review and meta-analysis

Our aim was to perform a qualitative review and a meta-analysis with 57 scientific articles (108 assays) published from 1 January 2000 to 31 June 2021 dealing with fumigant toxicity of essential oils (EOs) against Sitophilus zeamais. The studies were obtained from four electronic databases: Web of Science, SCOPUS, PubMed, and Google Scholar. The survey comprised 107 plant species belonging to 26 different families. Lethal concentration values (LC₅₀) of EOs were included in a random-effect model, and two subgroups were defined: “until 24 h” and “more than 24 h”. The EOs more frequently evaluated were those belonging to Lamiaceae (20.18%), Asteraceae (17.43%), Apiaceae (9.17%), and Rutaceae (6.42%). The global mean value was 21.37 (CI₉₅ 16.84–27.12), while the summary mean values of the subgroups were 41.45 (CI₉₅ 31.10–55.26) for “until 24 h” and 8.45 (CI₉₅ 5.72–12.48) for “more than 24 h”. Most species belonging to Apiaceae, Lamiaceae, Asteraceae, and Schisandraceae reported the highest insecticidal effects with mean values that ranged from 1.31 to 27.39 for “until 24 h” and from 0.57 to 5.31 for “more than 24 h”. Additionally, the toxicity of the most effective EOs was discussed by addressing their chemical composition and their major pure compounds chemical features.

     

Reaeration Coefficient Estimate: New Parameter for Predictive Equations

The reaeration coefficient (K _a) is an essential parameter to predict the dissolved-oxygen concentration in different aquatic ecosystems. The techniques applied to K _a estimates require considerable efforts, since measuring this coefficient is a laborious and expensive task. Thus, the use of predictive equations wherein K _a is found through hydraulic flow parameters is common. However, the available prediction equations lead to estimates often different from each other. A new predictive equation is addressed in the present study. The insertion of a dimensionless number resulting from the relation between the RMS (Root Mean Square) of the free-surface vertical velocity and the surface flow velocity is the great innovation of the study. The reaeration experiments and the surface vertical velocity mapping were performed in a circular hydraulic channel. The flow velocity varied from 0.25 to 0.64 m s^?1, and depth varied from 0.09 to 0.15 m. The new equation led to more accurate results than the equations based on traditional hydraulic parameters such as the Reynolds and Froude numbers, mainly when it comes to K _a values higher than 40 day^?1. The sensitivity analysis has shown that the new dimensionless number is the most sensitive parameter of the herein proposed predictive equation and that the influence from the Reynolds and Froude numbers on K _a weakens as turbulence gets more intense.     

Compensatory growth and feed restriction in marine shrimp production,with emphasis on biofloc technology

In Brazil, studies and production of penaeid shrimp in a biofloc technology (BFT) system are recent, but the results point to a promising future. Research with feed restriction inducing compensatory growth in shrimps has been shown to be a technique that allows a saving of around 25% in the use of feed for shrimp production. It also allows the reduction of costs with salaries and adapts shrimp farming to the world demand for environmentally friendly production, with the reduction of nitrogen and phosphorus levels in its effluents, as well as lower water use in shrimp farming. In crustaceans, it has been shown that after a period of feed restriction, the animals show a pronounced compensatory growth when they return to a sufficient food source. Studies with the penaeid shrimp Litopenaeus vannamei reported the ability of the species to obtain a complete compensatory growth after short feeding periods (1 to 3 days) followed by feeding; These short periods of fasting presented a greater efficiency in the feed conversion besides the decrease in the concentration of phosphorus present in the aquatic environment, coming from the excreta. The adoption of a restriction program in the feeding using BFT may contribute to a reduction in operating costs, reduction of metabolic nutrients dissolved in water, and, consequently, an increase in the number of cycles in which the same water can be reused for production reducing production costs and improving productivity indices in shrimp farming.     

Alligator gar (Atractosteus spatula,Lacépède 1803) vitellogenin: purification,characterization and establishment of an enzyme‐linked immunosorbent assay

Alligator gar (Atractosteus spatula) is a non‐teleost bony fish distributed in North America. Gar populations have drastically declined as a consequence of habitat deterioration and the lack of regulation for their capture. Control of reproduction is critical for recovering their natural populations. The impossibility to distinguish genders and the determination of sexual maturity have hindered their successful reproduction. This research was aimed at developing an enzyme‐linked immunosorbent assay (ELISA) for the quantitative estimation of vitellogenin (VTG), a female‐specific protein. Plasmatic VTG from 17β‐estradiol (E2)‐induced juveniles and ovary vitellin from adult females were purified and characterized. Polyclonal antibodies against both proteins were produced to develop an ELISA. The immunoassay was validated by quality tests such as sensitivity, parallelism, recovery, reproducibility and specificity. Vitellogenin was determined in different tissues (plasma, mucus, liver and gills) of alligator gar. Vitellogenin and E2 concentrations in female breeders were found to be higher in November, before the spring spawning season. This approach represents a quick, reliable and non‐invasive practical alternative to distinguish genders and evaluate gonad maturation.     

Phosphorus cycling in primary and secondary seasonally dry tropical forests in Mexico

? Primary forests in the seasonally dry tropical regions of Mexico are disappearing under land-use pressure, creating a mosaic of secondary forests of different ages.

? In this study we measured the aboveground litterfall phosphorus (P) fluxes, litter-layer and soil P pools to compare the P cycles in primary and secondary seasonally dry tropical forests. Our hypothesis was that the previous agricultural land use of secondary forests would bring about a lower P flux in the litterfall, lower soil P pool, and higher nutrient resorption proficiency than in primary forests, as well as an increase of relative amounts of available P provided by the soil with forest aging.

? The expected litterfall P flux increase in the secondary forest following a previous agricultural land use did not occur. Phosphorus return to the soil by aboveground litterfall was unaffected by the succession stage of the forest. In addition, the total soil P pool did not change with forest age. However, available soil P (bicarbonate P-inorganic and P-organic pools) and hydroxide inorganic P pools were higher in primary than in secondary forest soils. Phosphorus concentration in litterfall increased significantly with forest age, suggesting that P is cycled more efficiently (by a higher nutrient resorption proficiency) when soil available P is less abundant. Despite these differences among forests, the results of our study gave evidence that P requirements by plants in primary and secondary forests are sufficiently met by the accumulation of dissolved (water extractable) P in the forest floor during the dry season and by soil bicarbonate-P pools.

? Our study on the effects of land cover change on P cycling, following the discontinuation of agricultural practices, leads to the conclusion that this ecosystem P dynamics will vary depending on the successional stage of the forests, and is strongly influenced by the seasonal rainfall pattern which determines plant-available P.

     

Fishless shallow lakes of Southern Patagonia as habitat for waterbirds at the onset of trout aquaculture

• 1. The Strobel Meseta, a basaltic plateau of Patagonia (Santa Cruz Province, Argentina), holds thousands of shallow fishless lakes that are prime habitat for many species of waterbirds, including some considered ‘near threatened’. In recent years, several lakes have been stocked with trout which has created uncertainty about the potential effects on the recipient ecosystem.
• 2. Limnological and topographical analyses were performed in a group of 32 lakes of the Strobel Meseta in order to characterize and classify individual lakes of the meseta based on their limnological and topographic features, analyze the association between lake type and use by aquatic birds in general and by the endemic hooded grebe (Podiceps gallardoi) in particular, and evaluate the overlap between trout aquaculture and critical habitat for waterbirds.
• 3. The lakes were classified by multivariate analyses into four characteristic types: turbid, high conductivity lakes (T), small vegetated lakes (SV) and larger lakes which were subdivided into either vegetated (LV) or unvegetated (LU). In general, macrophyte cover was the main classificatory variable, whereas conductivity, pH, surface, and depth contributed moderately. Large vegetated lakes were generally found to be important for waterbirds and provided critical habitat for the hooded grebe, whereas trout farmers largely favoured large unvegetated lakes. However, since some large vegetated lakes have already been stocked, there is some level of geographical overlap between waterbird habitat and trout farming.
• 4. The existence of some level of spatial segregation between production and critical waterbird habitat affords opportunities for designing a spatially‐based management system for trout aquaculture.

Copyright © 2008 John Wiley & Sons Ltd.     

Wild halophytic species as forage sources: Key aspects for plant breeding

The use of wild halophytic species as forage resources in saline environments has gained increasing attention. Argentina ranks third in area of saline soils in the world, with a third of its territory showing various degrees of salinity, sodicity and/or alkalinity. On this type of soils, rangelands are the main forage resource for livestock production. Many wild species have forage potential and can also be used for the rehabilitation of rangelands and for intercropping. Information about these species, as well as on the physiological and genetic bases associated with salinity tolerance, provides relevant tools for efficient selection methods. This study addresses Argentine wild halophyte species with forage potential and describes selection criteria with an emphasis on the following taxa: (a) Poaceae: subfamily Chloridoideae and tribes Paniceae and Triticeae, (b) Fabaceae and (c) Amaranthaceae (formerly known as Chenopodiaceae). The review is intended to contribute to the general discussion on strategies for the improvement of wild plant genetic resources, using forage species naturally growing in saline soils in Argentina as a case study.     

Expression of dmrt1 and sox9 during gonadal development in the Siberian sturgeon (Acipenser baerii)

The sex differentiation period of the Siberian sturgeon was investigated through expression profiling of two testicular markers (dmrt1 and sox9). At the molecular level, a clear sexual dimorphism of dmrt1 and sox9 was observed in 3-year-old fish with immature gonads, in which males showed higher expression of these genes. Among 16-month-old sturgeons cultured in Uruguay, gonad morphology analyses showed one group of fish with undifferentiated gonads and a second group which had started their histological differentiation into ovaries or testes. dmrt1 showed a significantly higher expression in testes of recently differentiated fish, but this was not the case for sox9. In undifferentiated fish, we observed two clearly different groups in terms of expression: one group of fish over-expressing male markers (dmrt1, sox9) and another group of fish showing very low expression of these genes. This suggests that fish undergoing male differentiation can be identified by their profiles of gene expression before they undergo morphological differentiation.