Search

BackgroundMahi-mahi (Coryphaena hippurus) is a commercially and ecologically important fish species that is widely distributed in tropical and subtropical waters. Biological attributes and reproductive capacities of mahi-mahi make it a tractable model for experimental studies. In this study, life development of cultured mahi-mahi from the zygote stage to adult has been described.ResultsA comprehensive developmental table has been created reporting development as primarily detailed observations of morphology. Additionally, physiological, behavioral, and molecular landmarks have been described to significantly contribute in the understanding of mahi life development.ConclusionRemarkably, despite the vast difference in adult size, many developmental landmarks of mahi map quite closely onto the development and growth of Zebrafish and other warm-water, active Teleost fishes.

The 2010 Deepwater Horizon oil spill coincided with the spawning season of many pelagic fish species in the Gulf of Mexico. Yet, few studies have investigated physiological responses of larval fish to interactions between anthropogenic crude oil exposure and natural factors (e.g. temperature, oxygen levels). Consequently, mahi mahi (Coryphaena hippurus) embryos were exposed for 24 hours to combinations of two temperatures (26 and 30°C) and six concentrations of oiled fractions of weathered oil (from 0 to 44.1 μg ∑50PAHs·L-1). In 56 hours post-fertilization larvae, heart rate, stroke volume and cardiac output were measured as indicators of functional cardiac phenotypes. Fluid accumulation and incidence of edema and hematomas were quantified as indicators of morphological impairments. At both 26 and 30°C, oil-exposed larvae suffered dose-dependent morphological impairments and functional heart failure. Elevation of temperature to 30°C appeared to induce greater physiological responses (bradycardia) at PAH concentrations in the range of 3.0-14.9 μg·L-1. Conversely, elevated temperature in oil-exposed larvae reduced edema severity and hematoma incidence. However, the apparent protective role of warmer temperature does not appear to protect against enhanced mortality. Collectively, our findings show that elevated temperature may slightly decrease larval resilience to concurrent oil exposure.

Cardiovascular performance is altered by temperature in larval fishes, but how acute versus chronic temperature exposures independently affect cardiac morphology and physiology in the growing larva is poorly understood. Consequently, we investigated the influence of water temperature on cardiac plasticity in developing mahi-mahi. Morphological (e.g. standard length, heart angle) and physiological cardiac variables (e.g. heart rate fH, stroke volume, cardiac output) were recorded under two conditions by imaging: (i) under acute temperature exposure where embryos were reared at 25°C up to 128 h post-fertilization (hpf) and then acutely exposed to 25 (rearing temperature), 27 and 30°C; and (ii) at two rearing (chronic) temperatures of 26 and 30°C and performed at 32 and 56 hpf. Chronic elevated temperature improved developmental time in mahi-mahi. Heart rates were 1.2-1.4-fold higher under exposure of elevated acute temperatures across development (Q10≥2.0). Q10 for heart rate in acute exposure was 1.8-fold higher compared to chronic exposure at 56 hpf. At same stage, stroke volume was temperature independent (Q10∼1.0). However, larvae displayed higher stroke volume later in stage. Cardiac output in developing mahi-mahi is mainly dictated by chronotropic rather than inotropic modulation, is differentially affected by temperature during development and is not linked to metabolic changes.

Marine carbonate production and dissolution are important components of the global carbon cycle and the marine alkalinity budget. Global carbonate production by marine fish (ichthyocarbonate) has been estimated to be as high as 9.03 Pg CaCO3 yr−1; however, the fate of ichthyocarbonate is poorly understood. High magnesium concentrations in ichthyocarbonate would traditionally suggest rapid dissolution under current marine conditions, but a correlation between dissolution rate and mol%MgCO3 has not been observed. Here, we aim to determine the role of organic coatings on dissolution rates of ichthyocarbonate in marine environments. We applied a combination of petrographic, geochemical, and microCT approaches to assess the quantity and distribution of organic matter in ichthyocarbonate produced by two species of marine fish, the Gulf toadfish (Opsanus beta) and the Olive flounder (Paralichthys olivaceus). We show that organic matter, including external coatings and embedded organic material, is volumetrically significant, ranging from 8.5% to 32.3% of ichthyocarbonate by volume. Bleach oxidation of external organic matter coatings increased the dissolution rate of ichthyocarbonate by more than an order of magnitude, suggesting these coatings serve to reduce reactive surface area of the mineral fraction in ichthyocarbonate. Assuming that organic coatings do not influence sinking rates, external coatings extend the depth of ichthyocarbonate persistence in the water column by ∼12–15×. Therefore, organic coatings are an important determinant of the role of ichthyocarbonate in the marine carbon cycle. Key Points: Ichthyocarbonate‐associated organic matter occurs as embedded material and exterior coatingsExterior organic matter coatings on ichthyocarbonate slow mineral dissolution by 12–15×Organic matter exerts an important control on ichthyocarbonate fate, and thus may determine the role of marine fish in the carbon cycle [ABSTRACT FROM AUTHOR]

Pop-up satellite archival tags (PSATs) have been used to demonstrate habitat utilization and large-scale migrations of aquatic species and are a critical tool to manage highly migratory fish populations. Use of PSATs has increased in recent years; however, few studies have investigated the physiological and behavioral effects of carrying a PSAT. To address this gap, young-adult mahi-mahi (Coryphaena hippurus; 25-35 cm fork length) were tagged with miniature PSATs and assessed in a two-part experiment utilizing swim tunnel respirometry and behavioral analysis of free-swimming individuals. Swim tunnel respirometry revealed significant reductions in the critical and optimal swimming speeds of tagged fish (10.2% and 20.9%, respectively), as well as significant reductions in maximum metabolic rate and aerobic scope (16.1% and 21.4%, respectively). In contrast, mean and maximum velocity, acceleration, total distance traveled, survival, and feeding success of free-swimming tagged fish showed no impacts of tagging compared with untagged conspecifics held in the same tank. The results of this study highlight the importance of considering multiple methodologies to assess the impacts of tagging fish and provide insight into the data collected by PSATs deployed on wild fish. Les etiquettes satellites detachables a archivage (PSAT) ont ete utilisees pour obtenir de l'information sur l'utilisation de l'habitat et les migrations a grande echelle d'especes aquatiques et elles constituent un outil d'importance critique pour la gestion des populations de poissons hautement migratoires. Si l'utilisation de PSAT a cru au cours des dernieres annees, peu d'etudes se sont penchees sur les effets physiologiques et comportementaux du port d'une PSAT. Pour remedier a cette situation, des coryphenes communes (Coryphaena hippurus) jeunes adultes (longueur a la fourche de 25-35 cm) ont ete munies de PSAT miniatures et evaluees dans le cadre d'une experience a deux volets faisant appel a la respirometrie en tunnel de nage et l'analyse comportementale de specimens nageant librement. La respirometrie en tunnel de nage revele des baisses significatives des vitesses de nage critique et optimale des poissons etiquetes (de 10,2 % et 20,9 %, respectivement), ainsi que des baisses significatives de la vitesse de metabolisme maximum et de la capacite metabolique aerobie (16,1 % et 21,4 %, respectivement). En comparaison, aucune influence de l'etiquetage sur les velocites moyenne et maximum, l'acceleration, la distance totale parcourue, le taux de survie et le succes d'alimentation n'a ete relevee chez les poissons etiquetes nageant librement comparativement a des conspecifiques non etiquetes maintenus dans le meme reservoir. Les resultats de l'etude soulignent l'importance d'envisager differentes methodologies pour l'evaluation des effets de l'etiquetage des poissons et permettent de mieux comprendre les donnees recueillies par les PSAT deployees sur des poissons sauvages. [Traduit par la Redaction], Introduction Mahi-mahi (Coryphaena hippurus), or dolphinfish, are a pelagic species found throughout the world's subtropical and tropical oceans (Gibbs and Collette 1959; Diaz-Jaimes 2010). As a high-performance predator in the [...]

Cobia, Rachycentron canadum, is an important species for aquaculture worldwide. Production technology from egg to market was established in the early 1990s and continues to be perfected to this day. This species exhibits extraordinary scope for growth and can reach between 4 and 8 kg in 1 year, with females growing almost twice as fast and large as males. Despite continuous progress in maturation, spawning, larval rearing, fingerling production, nutrition, health management, genetics, and growout technology, overall cobia aquaculture production worldwide has been slow in the last decade. One of the biggest challenges remains the development of practical commercial feeds that are ecologically and economically efficient for this species. Feed conversion ratios are still very high, ranging from 2.0 to 3.0:1. In addition to nutritional challenges, diseases such as Photobacterium, Amyloodinium ocellatus, and Brooklynella hostilis continue to impact cobia aquaculture production worldwide. Genetics and breeding programs for cobia are still at their infancy. We report on current status of cobia breeding efforts as well as on advances on developing female monosex populations to exploit the sexually dimorphic growth in this species. Nutrition, health, and genetics will be the greatest drivers to improve overall performance and increases in production of the cobia aquaculture industry. [ABSTRACT FROM AUTHOR]

The potential for marine aquaculture development in the United States is significant and recent factors have highlighted the benefits of developing a shortened seafood supply chain to service domestic markets. Marine finfish in particular hold tremendous potential as technological advancements, improvements in production efficiencies, and market forces have aligned to create opportunities for growth within this sector of the aquaculture industry. Olive flounder, Paralichthys olivaceus, also commonly known as the Japanese flounder or hirame, is a candidate species for the U.S. aquaculture industry, which has a demonstrated track record of culture success and high market value. Although cultivation of the species is novel to the United States, olive flounder has been produced commercially for decades in other regions, notably Korea and Japan. With a number of favorable production characteristics, including a relatively short growout time compared with other flatfish species, an efficient food conversion ratio, and a well‐established market presence, the species has been shown to be commercially viable. This study examines the opportunities for olive flounder to be developed in the United States, while also discussing the potential for land‐based recirculating aquaculture systems culture of this species in coastal areas to provide increased resilience for working waterfront communities. [ABSTRACT FROM AUTHOR]