Endocrine, Physiological and Histopathological Responses of Fish and their Larvae to Stress with Emphasis on Exposure to Crude Oil and Various Petroleum Hydrocarbons

Abstract

ABSTRACT:Various endocrine and physiological responses of fish exposed to forceful physical and chemical stimuli are reviewed with emphasis on the effects of crude oils and their hydrocarbon constituents. The chemistry and toxicity of petroleum hydrocarbons are examined and methods for experimental exposure of fish to crude oil and petroleum hydrocarbons are considered. A variety of blood-borne parameters recognized as reliable tools in determining the relative severity of stress in fish are reviewed. The effects of stress and petroleum hydrocarbons on endocrine responses including changes in plasma AL-KINDI, BROWN, and WARING catecholamines, corticosteroids, and thyroid hormones are reviewed. The physiological responses: changes in plasma glucose, osmotic and ionic regulation, blood oxygen, hematocrit and hemoglobin concentration are explored, and histopathological effects of crude oil on fish are reviewed. Recent studies of the effects of petroleum hydrocarbons on fish larvae are considered and the increased sensitivity of the early life stages of fish are highlighted.

Plasma Analysis in Normal Green Sea Turtles, Chelonia mydas, During two Different Periods of Nesting at Ras Al- Hadd, Sultanate of Oman

“…In comparing the present electrolyte data, we find that Na + , K + , Ca ++ and Mg ++ levels were significantly higher during peak periods over non-peak periods, while Cland PO 4 -3 were not significantly different. The differences in values may be related to stress which has been known to change the electrolyte levels in fish (see AlKindi, et al, 2000a), or the differences could be related to individual variations at the time of sampling. During the peak period, nesting turtles are under tremendous pressure because of crowding stress, which may contribute to the rise in electrolyte levels.…”

“…On land, the green turtles, during nesting exercise, ventilate intermittently, depending primarily on anaerobic respiration (AlKindi, et al, 2000b). Dissociated products of lactic acid (lactic ions and H + ) can cause severe acid-base disturbances and can hinder the oxygen uptake but catecholamine immediate release can facilitate oxygen uptake in most vertebrates (AlKindi, et al, 2000a). In fishes, blood osmolarity and electrolyte concentrations may be affected by stress (Aldrin, et al, 1979;AlKindi, et al, 2000a), hypoxia, certain environmental pollutants (Alkindi, et al, 1996) and osmoregularity dysfunction, which is characterized by blood electrolyte imbalance (Carmichael, et al, 1984b;AlKindi, et al, 1996;AlKindi, et al, 2000a).…”

“…Nesting is a long ordeal and usually takes between 2.5-4.5hr, sometimes longer. Under these conditions, the green turtles are subjected to a high degree of stress, evidenced by high plasma catecholamine levels during nesting exercises compared to lower levels when the green turtles first emerge from the sea (AlKindi, et al, 2000). They undergo bursts of strenuous and exhaustive forceful exercise which usually last for less than one minute followed by a recovery period lasting 10-30 seconds for deep breathing (AlKindi, unpublished data).…”

“…Under these exercise-recovery phases as shown in the present data, the turtles develop apnea accompanied by hypercapnia and acidemia associated with high-rise in CO 2 , which is primarily related to anaerobic metabolism. This condition persists throughout the nesting exercises as catecholamines play a major role in glycogen metabolism by stimulating glycogenolysis and/or gluconeogenesis (AlKindi, et al, 2000).…”

Physiological and Behavioral Adjustments Relative to Catecholamine Levels During Nesting in Olive Ridley (Lepidochelys Olivacea) and Hawksbill (Eretmochelys Imbricata) Sea Turtles in Masirah Island, Oman.

“…T he stress system in vertebrates, under the influence of the environmental factors, triggers the neuroendocrine system to secrete stress hormones such as catecholamines and glucocorticoids (Stratakis and Chrousos, 1995;AlKindi et al, 1996;AlKindi et al, 2000a;Denver, 1997). In addition to hormones, there is also an increase in glucose, lactate and blood electrolytes (Chrousos and Gold, 1992).…”