Interactive effects of pesticide exposure and habitat structure on behavior and predation of a marine larval fish

Coastal development has generated multiple stressors in marine and estuarine ecosystems, including habitat degradation and pollutant exposure, but the effects of these stressors on the ecology of fishes remain poorly understood. We studied the separate and combined effects of an acute 4 h sublethal exposure of the pyrethroid pesticide esfenvalerate and structural habitat complexity on behavior and predation risk of larval topsmelt (Atherinops affinis). Larvae were exposed to four nominal esfenvalerate concentrations (control, 0.12, 0.59, 1.18 μg/L), before placement into 12 L mesocosms with a three-spine stickleback (Gasterosteus aculeatus) predator. Five treatments of artificial eelgrass included a (1) uniform and (2) patchy distribution of eelgrass at a low density (500 shoots per m(2)), a (3) uniform and (4) patchy distribution of eelgrass at a high density (1,000 shoots per m(2)), and (5) the absence of eelgrass. The capture success of predators and aggregative behavior of prey were observed in each mesocosm for 10 min of each trial, and mortality of prey was recorded after 60 min. Exposure to esfenvalerate increased the proportion of larvae with swimming abnormalities. Surprisingly, prey mortality did not increase linearly with pesticide exposure but increased with habitat structure (density of eelgrass), which may have been a consequence of compensating predator behavior. The degree of prey aggregation decreased with both habitat structure and pesticide exposure, suggesting that anti-predator behaviors by prey may have been hampered by the interactive effects of both of these factors

Congenital Choledochal Malformation: Not Just a Problem for Children

Choledochal cysts remain relatively uncommon in Western Europe and the US, although they are appreciably more common in Asia. Their aetiology remains obscure although abnormalities of the pancreaticobiliary junction may be the primary pathology in some, with biliary dilatation following reflux of activated pancreatic secretions. Most anomalies will present in childhood with obstructive jaundice or abdominal pain; a proportion may only present for the first time during adulthood, and some of these will show malignant transformation. The classical triad of pain, jaundice and a palpable mass is, however, not common. Complete cyst excision, where possible, and biliary reconstruction remain the aims for most types although there is still some controversy about the type of reconstruction. Laparoscopic reconstruction is possible but is still very much an advanced technique. The risk of long-term problems post-surgery is significant. Whether this is due to recurrent pancreatitis secondary to the retained common channel and/or a distal stump, or due to the development of biliary tract malignancy is still a cause for concern and indicates the need for adequate, prolonged follow-up