title: The influence of salinity and temperature change on the functioning of the urinary bladder in the early larval stages of the atlantic herring Clupea harengus L.
abstract: Major changes in the morphology of the urinary bladder were observed during the transition from yolk-sac to feeding larval stages of herring, in particular bladder volume increased almost sixfold. Initially, the urine flowed into the hindgut, but within days of hatching a separate urinary duct, leading to the exterior, had formed. Micturation was intermittent but quite regular. The period between micturations increased from 1.6 to 4 min in the progression between the two larval stages. The discharge volume was approximately 50 % of the full bladder volume in all stages studied. Urine flow rate (UFR) in sea water rose slightly from 1 to 1.7 nl mg(-)(1 )h(-)(1) during early larval development. Exposure to low salinities significantly reduced UFR in yolk-sac larvae, but in the later stages UFR increased significantly in hypo-osmotic salinities, so that UFR in 4 salinity was 2.5 times that in 34 salinity. The main variable influencing UFR was discharge frequency. Cardiac output was not influenced by salinity and was considered not to be a controlling factor in the UFR response to salinity change. UFR increased with temperature with Q(10) of 2.3 in stage 1 larvae and 1. 5 in stage 2 larvae, over 7-15 degrees C.
authors.affiliation: Department of Biological and Molecular Sciences, University of Stirling, Stirling FK9 4LA, UK. PT1@stir.ac.uk
authors.forename: P
authors.initials: P
authors.lastname: Tytler
authors.forename: J
authors.initials: J
authors.lastname: Ireland
mesh_terms: D000818:Animals; D005399:Fishes / Q000502:physiology*; D006439:Hemodynamics / Q000502:physiology; D006358:Hot Temperature; D007814:Larva; D012623:Seawater / Q000737:chemistry; D001743:Urinary Bladder / Q000033:anatomy & histology / Q000196:embryology* / Q000502:physiology; D014563:Urodynamics / Q000502:physiology; D014741:Video Recording