Brevetoxin in two planktivorous fishes after exposure to Karenia brevis: implications for food-web transfer to bottlenose dolphins

Brevetoxin uptake was analyzed in 2 common planktivorous fish that are likely foodweb vectors for dolphin mortality events associated with brevetoxin-producing red tides. Fish were exposed to brevetoxin-producing Karenia brevis for 10 h under conditions previously reported to produce optimal uptake of toxin in blood after oral exposure. Striped mullet Mugil cephalus were exposed to a low dose of brevetoxin, and uptake and depuration by specific organs were evaluated over a 2 mo period. Atlantic menhaden Brevoortia tyrannus specimens were used to characterize a higher brevetoxin dose uptake into whole body components and evaluate depuration over 1 mo. We found a high uptake of toxin by menhaden, with a body to water ratio of 57 after a 10 h exposure and a slow elimination with a half life (t1/2) of 24 d. Elimination occurred rapidly from the intestine (t1/2 < 1 wk) and muscle (t1/2 ≈ 1 wk) compartments and redistributed to liver which continued to accumulate body stores of toxin for 4 wk. The accumulation and elimination characteristics of the vectoring capacity of these 2 fish species are interpreted in relation to data from the Florida Panhandle dolphin mortality event of 2004. We show that due to slow elimination rate of brevetoxin in planktivorous fish, brevetoxin-related dolphin mortality events may occur without evidence of a concurrent harmful algal bloom event.

Immunomodulatory effects of domoic acid differ between In vivo and In vitro exposure in mice

The immunotoxic potential of domoic acid (DA), a well-characterized neurotoxin, has not been fully investigated. Phagocytosis and lymphocyte proliferation were evaluated following in vitro and in vivo exposure to assay direct vs indirect effects. Mice were injected intraperitoneally with a single dose of DA (2.5 µg/g b.w.) and sampled after 12, 24, or 48 hr. In a separate experiment, leukocytes and splenocytes were exposed in vitro to 0, 1, 10, or 100 µM DA. In vivo exposure resulted in a significant increase in monocyte phagocytosis (12-hr), a significant decrease in neutrophil phagocytosis (24-hr), a significant decrease in monocyte phagocytosis (48-hr), and a significant reduction in T-cell mitogen-induced lymphocyte proliferation (24-hr). In vitro exposure significantly reduced neutrophil and monocyte phagocytosis at 1 µM. B- and T-cell mitogen-induced lymphocyte proliferation were both significantly increased at 1 and 10 µM, and significantly decreased at 100 µM. Differences between in vitro and in vivo results suggest that DA may exert its immunotoxic effects both directly and indirectly. Modulation of cytosolic calcium suggests that DA exerts its effects through ionotropic glutamate subtype surface receptors at least on monocytes. This study is the first to identify DA as an immunotoxic chemical in a mammalian species.

Histopathological changes in gill, kidney and liver of an estuarine mullet, Liza parsia, induced by sublethal exposure to DDT

Liza parsia were exposed to sublethal (0.02 ppm) concentration of DDT for 15 days. The gill responded initially with copious secretion of mucus, oedematous separation of epithelial cells from the basement membrane and fusion of secondary gill lamellae. Hyperplasia of the cells lining primary gill lamellae and lamellar telangiectases (or aneurysms) was frequently seen after day 10 of exposure. Kidney exhibited hypertrophy of the epithelial cells lining proximal convoluted tubules which was followed by shrinkage in glomerular tufts, increase in Bowman's space, appearance of amorphous eosinophilic materials in the lumina of the tubules and focal necrosis on day 10 of the treatment. Hyaline droplets and casts were also encountered in the epithelial cells and lumina of the proximal tubules. Liver revealed an initial dilation of canaliculi and increased secretion of bile. Thereafter, the displacement of nuclei towards periphery of the hepatocytes, disorganization of blood sinusoids, pyknotic changes in nuclei, cytolysis and vacuolation as well as focal necrosis were noticed after day 10 of the intoxication.

Haematological and biochemical alterations of Catla catla fingerlings following sublethal exposure to Nuvan

The sublethal exposure (0.24 ppm) of Nuvan on some biochemical compositions such as serum protein, blood glucose, glutamate oxaloacetate transaminase (AST) and glutamate pyruvate transaminase (ALT) and on some hematological parameters such as red blood corpuscles (RBC), white blood corpuscles (WBC), hemoglobin content (Hb), mean corpuscular concentration (MCV), mean corpuscular hemoglobin concentration (MCHC) of Catla catla fingerlings were studied. The hematological and biochemical parameters evoked a significant reduction (excepting MCV, ALT and AST which is significantly increased) with increasing days of Nuvan exposure.

Effect of long-term exposure to endosulfan on blood cell count in Channa gachua

In the present investigation, live specimens of Channa gachua were exposed to sublethal concentrations, i.e., 0.0017 and 0.00087 ppm of endosulfan for a period of 60 days. After the completion of 60 days, red and white blood corpuscles were counted from control as well as experimental fishes.

Tensile strength properties of polyethylene netting twines under exposure to out-door and artificial UV radiation

Photodegradation of three types of polyethylene twines namely, polyethylene fibrillated tape twine, polyethylene flat tape twine and polyethylene monofilament twines were studied by exposing them to sunlight and artificial UV radiation. The percentage residual strength varied in the samples, the monofilament with the highest residual strength followed by fibrillated tape twine and flat tape twine. A plot of the difference between the breaking strengths of the fibrillated tape twine and the mono filament twines against any given period of exposure exhibited a linear relationship

Gill lesions associated with acute exposure to ammonia

Histopathological effects of ammonia on the gills of milkfish (Chanos chanos ) fingerlings were examined qualitatively.

Report of the MPA exposure visit to Malaysia, 29 March-02 April, 2015

The main objective of the visit was to share the success of Marine Protected Area (MPA) management in Malaysia with Bangladeshi counterparts, representatives of donor organizations, NGOs and researchers.

Widows' struggles in post-war Sri Lanka

This report documents the post-war struggle of women, mainly widows, from the fishing communities of Mannar, Sri Lanka, attempting to reconstruct their lives.