Impact of salinity changes on growth, oxygen consumption and expression pattern of selected candidate genes in the orange mud crab (Scylla olivacea)

Change in environmental salinity level is a major limiting factor for the aquaculture productivity because it imposes severe stress on organisms that in turn retards growth. The orange mud crab (Scylla olivacea) is an important coastal aquaculture species (farming is practised in 10‰–20‰ salinity levels) in Bangladesh. The present study was conducted to investigate the changes in growth, O2 consumption and mRNA expression levels of five selected genes in the orange mud crab (S. olivacea) exposed to three different experimental salinity levels (0‰, 10‰ and 20‰) for three months. Crabs reared at 10‰ and 20‰, showed significantly higher (p < .05) growth performance and expression of growth regulatory genes (Actin and α-amylase). The highest levels (p < .05) of O2 consumption and expression of ion regulatory genes (Na+-K+-ATPase, V-type H+-ATPase and Diuretic Hormone) were obtained at 0‰. Moderate levels of growth and expression of selected candidate genes were observed at 10‰ treatment while the highest levels of growth and gene expression were obtained at 20‰ (control salinity). Strong interactions were observed between growth performance and expression of growth genes (R2 = 0.81–0.91), and rate of O2 consumption and expression of ion regulatory genes (R2 = 0.83–0.93), implying that the selected genes are important candidates for growth and ionic balance in S. olivacea. Growth performance was found to be very low at 0‰ initially, after 30 days crabs showed better growth performance at this salinity level. It is thus inferred that orange mud crab individuals might require 3–5 days for acclimation to salinity stress but it can take at least 30 days for acclimation to regular growth. Results indicate that with proper acclimation, the orange mud crab (Scylla olivacea) can be farmed at low salinity conditions and possibly in freshwater condition

Sismicità all’Etna dal 1989 al 2010: evidenze sull’evoluzione spazio-temporale dell’attività sismica

Il Monte Etna, uno dei più attivi vulcani basaltici tra i più monitorati al mondo, è sede di una notevole attività sismica e vulcanica. Esso è ubicato in Sicilia orientale in un complesso quadro geodinamico, dove le principali strutture tettoniche regionali giocano un ruolo chiave nei processi dinamici del vulcano. La sismicità dell’Etna si manifesta con un elevato rate di terremoti di bassa e moderata energia che, a volte, a causa dell’estrema superficialità della sorgente, provocano danni ai centri abitati prossimi all’area epicentrale. Il monitoraggio sistematico dell’attività sismica etnea è effettuato sin dal 1989, mediante una rete sismica locale permanente che nel tempo è stata oggetto di importanti miglioramenti. La prima configurazione di rete era costituita da circa 10 stazioni analogiche con sensori a corto periodo gestita dall’Istituto Internazionale di Vulcanologia (IIV-CNR). Nel 1994, una rete sismica costituita da circa 40 stazioni (analogiche con sensori a corto periodo) fu installata sull’Etna nell’ambito del Progetto Poseidon. Nel 2001, le reti gestite dall’IIV-CNR e dal Progetto Poseidon confluirono nell’Istituto Nazionale di Geofisica e Vulcanologia (INGV); attualmente la rete sismica, costituita da circa 50 stazioni digitali equipaggiate con sismometri broadband a tre componenti, è gestita dalla Sezione di Catania dell’INGV. Nel periodo 1989-1999, il catalogo dei terremoti risulta costituito da circa 2000 eventi con soglia di completezza per magnitudo pari a 2.0; dal 1999 ad oggi contiene circa 6000 terremoti con soglia di completezza per magnitudo 1.5. La capacità di detezione della rete è migliorata nel tempo permettendo di registrare e localizzare anche gli eventi meno energetici (M≥1.0). In questo lavoro, vengono presentati i caratteri predominanti della sismicità etnea negli ultimi 20 anni, con un maggiore dettaglio della distribuzione spazio-temporale della sismicità verificatasi dal 1999. L’analisi della attività sismica rappresenta un utile strumento per l’interpretazione delle dinamiche che hanno contraddistinto numerose ed importanti eruzioni (2001, 2002-03, 2004, 2006, 2008-09). In particolare, la variazione del rilascio energetico della sismicità ha contribuito in maniera significativa ad identificare i probabili processi geodinamici legati alla ricarica del sistema magmatico del vulcano. La distribuzione spaziale della sismicità ha consentito di evidenziare inoltre l’esistenza di diverse aree sismogenetiche caratterizzate da un differente rate sismico, profondità focali e cinematica delle strutture associate. Infine, osservando le caratteristiche della sismicità nel lungo periodo, differenti settori del vulcano sono risultati maggiormente attivi in relazione ai più importanti recenti eventi eruttivi

The Transition from Unregulated to Regulated Fishing in Thailand

Marine fishery is an economically important sector and the primary source of livelihood for coastal fishers in Thailand, but the open access harvesting system and overfishing have depleted fish stocks. The country should address both the issues to sustain a healthy marine fishery and protect the lucrative export market as well as to maintaining seafood self-sufficiency. This paper explains the on-going processes of implementing the measures of restricting the number and size of fishing vessels and fishing efforts to control fishing capacity. The marine resources in the Gulf of Thailand and the Andaman Sea are categorized into three separate species groups: (1) demersal, (2) pelagic, and (3) anchovies. The precautionary approach is used as the guiding principle, and maximum sustainable yield (MSY) of the three combined resource categories is used as a reference point in setting the total allowable catch (TAC) limits in this exercise. The number of fishing days per vessel per year is stipulated by issuing licenses based on the TAC size and total allowable effort (TAE). Both the advantages and disadvantages of the current fishing allocation system are discussed

Assessing farmers access to ICT and non-ICT sources for agricultural development in Semi-Arid Region in India

This study examines farmers’ access to Information and Communication Technologies (ICT) and Non-ICT systems in the semi-arid region in the state of Rajasthan in India. The Primary data was collected from 133 farmers consisting of 68 ICT users, 62 Non-ICT users, and three moderate users. The empirical results of the multiple regression analysis revealed that education level and landholding size (in acres) influences farmers’ access to ICT and non-ICT systems. However, household labor variable adversely affects access to technology. It also concludes that comparatively female farmers have lesser access to ICT. The empirical results of the multiple regression analysis revealed that education level and landholding size (in acres) positively influences farmers’ access to ICT systems. However, household labor variable adversely affects access to ICT technology. It also concludes that comparatively female farmers have lesser access to ICT. Consequently, there was significant positive influence of land holding size (acres) and negative influence of education level on Non-ICT access.The study recommends educating and sensitizing farmers about the benefits of ICT, coordination between government and private sectors for the effectual development of ICT, creating effective linkages of Krishi Vigyan Kendras (Farm Science Centers)(KVKs), Agriculture Extension as a profession for farmers and 24×7 television and radio channels dedicated to agriculture. This study can be used for productive implementation of ICT and Non-ICT sources considering the socio-economic characteristics of farmers in the similar situation

Evaluating Farmers’ Access to Agricultural Information: Evidence from Semi-Arid Region of Rajasthan State, India

The rural farmers in western Rajasthan State are uneducated and most of the applications of Information and Communication Technology (ICT) are demonstrated and run in the English Language. The majority of these rural farmers who are illiterates with a very low level of understanding of the English Language find it difficult to take advantage of the availability of ICT to facilitate their access to information for their farm businesses. This study examined the role of ICT in enhancing the farmers&#8217; access to production and marketing information in western Rajasthan State in India. Primary data was collected from 133 farmers consisting of 71 ICT users and 62 Non-ICT users through questionnaire administration. The results of the Analysis of Variance test regarding the farmers&#8217; access to different types of production and marketing information revealed that the user type (i.e., ICT versus Non-ICT user) significantly explains the differences in farmers&#8217; access to the different types of marketing and production information. These results are consistent with the empirical results of the student&#8217;s t-test that farmers&#8217; access to different types of production and marketing information from ICT sources is significantly higher than from Non-ICT sources. Consistently, the empirical results of the multiple regressions revealed that the percentage of production and marketing information obtained from ICT sources had positive significant influence on the farmers&#8217; access to marketing and production information; and that the percentage of marketing and production information obtained from Non-ICT sources had negative significant influence on the farmers&#8217; access to marketing and production information. These results suggest that ICT sources of marketing and production information play a crucial role in the farmers&#8217; access to this information for their business operations. The implication is that proper education and training of farmers (especially the female farmers) about the utilization of ICT sources to accelerate access to information is crucial

Physiological, biochemical and genetic responses of black tiger shrimp (Penaeus monodon) to differential exposure to white spot syndrome virus and Vibrio parahaemolyticus

The black tiger shrimp (Penaeus monodon) represents a major crustacean aquaculture species globally. Outbreaks of diseases caused by two particular pathogens, Vibrio parahemolyticus (VP) and white spot syndrome virus (WSSV) severely hamper the production performance of this species. The present study investigated the effects of different doses of the two pathogens on physiological/biochemical parameters and differential gene expression in P. monodon. This study involved 10 different experimental groups including nine treatments (three doses of VP: T1 – T3, three doses of WSSV: T4 – T6 and three combined VP + WSSV doses: T7 – T9) and a control. VP and WSSV treatments significantly reduced hemocyte counts of shrimp hemolymph (P 2 consumption rates in the pathogen-treated shrimp, T1 – T9 (P 1 – T9). Results indicate that different doses of pathogenic exposure significantly altered the expression of candidate genes together with changes in physiological (O2 consumption rates) and biochemical (hemocyte counts, glucose and serotonin levels of hemolymph) parameters that adversely affected growth and mortality of experimental shrimps

Optimization of Macroalgal Density and Salinity for Nutrient Removal by <i>Caulerpa lentillifera</i> from Aquaculture Effluent

Determining the optimum levels of macroalgal density and salinity for removing aquaculture effluent has gained increasing research interest in recent years because of the growing concerns over environmental sustainability. Here, we determined the effects of macroalgal density and salinity on the uptake of NO2&#8722;, NO3&#8722;, NH3, and PO43&#8722; by Caulerpa lentillifera from the effluent of Poecilia latipinna using spectrophotometry. Laboratory experiments were conducted to measure nutrient uptake at five different macroalgal density levels (10, 20, 30, 40, and 50 g/L) and three salinity levels (20, 30, and 40 ppt) with and without aeration. Quadratic regression analysis revealed significant nonlinear and linear effects of macroalgal density on the uptake of NO2&#8722;, NO3&#8722;, NH3, and PO43&#8722;, where the maximum uptake was predicted to occur at the macroalgal densities of 31.6, 33.3, 50.0, and 20.0 g/L, respectively. Likewise, the effects of salinity on the uptake of NO2&#8722;, NO3&#8722;, NH3, and PO43&#8722; were significant and nonlinear where the maximum uptake was predicted to occur at the salinity levels of 29.1, 30.7, 29.5, and 29.5 ppt, respectively. The result of the effects of aeration was mixed but somewhat indicated a positive effect on the nutrient uptake within the 24 h period. Our results could help aquaculturists to minimize the excessive nutrients by C. lentillifera from aquaculture effluent while achieving long-term sustainable aquaculture production