Publications by authors named "Alexis J Khursigara"

Article Synopsis
  • Mercury is a significant global contaminant that poses serious health risks to organisms, particularly affecting the Dusky Grouper in Brazil.
  • The study examined total mercury levels in the fish's muscle tissue, how these levels relate to the fish's size, and their association with stable isotopes, along with comparing mercury concentrations in different tissues.
  • Findings showed that 21.8% of the sampled fish had mercury levels exceeding safe human consumption limits, with concentrations increasing at lower latitudes and varying significantly between muscle, liver, and ovary tissues.
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Crude oil is known to induce developmental defects in teleost fish exposed during early-life stages (ELSs). A recent study has demonstrated that zebrafish (Danio rerio) larvae acutely exposed to Deepwater Horizon (DHW) crude oil showed transcriptional changes in key genes involved in early kidney (pronephros) development and function, which were coupled with pronephric morphological defects. Given the osmoregulatory importance of the kidney, it is unknown whether ELS effects arising from short-term crude exposures result in long-term osmoregulatory defects, particularly within estuarine fishes likely exposed to DWH oil following the spill.

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Crude oil and the constituent polycyclic aromatic hydrocarbons (PAHs) induce a consistent suite of sub-lethal effects in early life stage fishes. It has been suggested that 3-ring PAHs drive cardiotoxicity and that all other impacts are downstream consequences of these cardiac effects. However, recent studies have documented behavioral alterations that may not be linked to cardiotoxicity.

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The 2010 Deepwater Horizon oil spill impacted over 2100 km of shoreline along the northern Gulf of Mexico, which coincided with the spawning season of many coastal species, including red drum (Sciaenops ocellatus). Red drum develop rapidly and are sensitive to crude oil exposure during the embryonic and larval periods. This study investigates the predictions from recent transcriptomic studies that cholesterol biosynthetic processes are impacted by oil exposure in fish early life stages.

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Article Synopsis
  • Measures of fitness, like aerobic scope (AS), help predict how species react to environmental changes, particularly with rising water temperatures.
  • Maximum metabolic rate (MMR) is influenced by an individual's oxygen delivery ability, and recent findings highlight that the activity of red blood cell carbonic anhydrase (RBC CA) limits oxygen delivery in red drum fish.
  • In experiments, increased temperature raised RBC CA activity and MMR significantly, but no direct relationship was found between RBC CA activity and MMR or AS, suggesting RBC CA does not predict individual metabolic performance despite its thermal sensitivity.
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Fishes exposed to crude oil have shown reduced sociability and poor habitat selection, which corresponded with increased predation risk. However, the contribution of oil-induced cardiorespiratory impairments to these findings is uncertain. This study explores the effect of oil exposure on predation risk in a model fish species, , across a suite of physiological and behavioral end points to elucidate the mechanisms through which any observed effects are manifested.

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Crude oil is a well-known toxicant that reduces cardiorespiratory performance in acutely exposed fishes. While toxic effects can manifest in death in severe cases, the ecological consequences of sub-lethal exposure remain uncertain. This study investigated the impact of crude oil exposure on long-term social competition, growth, and metabolic performance in a coastal species, the red drum (Sciaenops ocellatus).

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Many animal taxa live in groups to increase foraging and reproductive success and aid in predator avoidance. For fish, a large proportion of species spend all or part of their lives in groups, with group coordination playing an important role in the emergent benefits of group-living. Group cohesion can be altered by an array of factors, including exposure to toxic environmental contaminants.

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Crude oil and its constituent chemicals are common environmental toxicants in aquatic environments worldwide, and have been the subject of intense research for decades. Importantly, aquatic environments are also the sites of numerous other environmental disturbances that can impact the endemic fauna. While there have been a number of attempts to explore the potential additive and synergistic effects of oil exposure and environmental stressors, many of these efforts have focused on the cumulative effects on typical toxicological endpoints (e.

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Polycyclic aromatic hydrocarbons (PAHs) present in crude oil can cause global gene dysregulation and developmental impairment in fish. However, the mechanisms that alter gene regulation are not well understood. In this study, larval red drum ( Sciaenops ocellatus) were exposed to water accommodated fractions of source oil (6.

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Polycyclic aromatic hydrocarbons (PAHs) present in crude oil have been shown to cause the dysregulation of genes important in eye development and function, as well as morphological abnormalities of the eye. However, it is not currently understood how these changes in gene expression are manifested as deficits in visual function. Embryonic red drum (Sciaenops ocellatus) and sheepshead minnow (Cyprinodon variegatus) were exposed to water accommodated fractions (WAFs) of weathered crude oil and assessed for visual function using an optomotor response assay in early life-stage larvae, with subsequent samples taken for histological analysis of the eyes.

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The present study examined impacts of crude oil exposure on dyad competition in juvenile red drum. Following the 2010 Deepwater Horizon oil spill, it has become well established that oil exposure can constrain maximum metabolic rate, reduce aerobic scope and exercise performance in marine fish. Aerobic scope is one of the physiological characteristics that is a known determinant of dominance in fish social hierarchy formation.

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The Gulf of Mexico was home to the Deepwater Horizon oil spill, and is also known to exhibit seasonal declines in oxygen availability. Oil exposure in fish is known to impact oxygen uptake through cardiac impairment, which raises questions about the additive effects of these two stressors. Here we explore this question on the Atlantic croaker using two measures of hypoxia tolerance: critical oxygen threshold (P), and time to loss of equilibrium (LOE).

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Article Synopsis
  • The study assessed the effects of weathered and non-weathered oil on red drum larvae, focusing on survival, physical deformities, and heart function.
  • The lethal concentration (LC50) values for red drum larvae were found to be between 14.6 and 21.3 μg/L ΣPAH, with no significant differences based on exposure timing or oil weathering.
  • Results showed that exposure led to major reductions in cardiac output, particularly affecting stroke volume rather than heart rate, highlighting a concerning sensitivity in cardiac function that aligns with findings in similar pelagic species.
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