1Announcements Aug 30• Field Opportunities – Cienega Creek• Volunteer Opportunity = The Wildlife Society Meeting Tucson• Lamprey Photos will be on WEB• EXAM 1 – Friday Sept 21Lecture 4 - Chpt 5 – Oxygen, Respiration, Gas Bladder and EnergeticsRespiration:- Oxygen - aquatic vs aira) Water 1% O2 vs. Air 21%- Water 800x dense and 50x more viscous; a) energetically more difficult to move and breath (fish 10% energy to breath vs. 1% terrestrial)- Temperature - 8 O2/l, 6.5, 5.6 in 10o, 20o, 30oC- Salt Effects – less O2 in salt water- Terrestrial = Bidirectional breathing vs. Fish = Unidirectional2Water vs Airdrymoistmoistmembrane state106x fasterslowdiffusiontransport1000 x lowerhighdensityventilationhigh (20 x that in water)lowsolubilityefficiencyAirAqueousMediumRespiratoryAttributesAffected functionGills – Site of Gas Exchange1) Bony or cartilaginous arches that anchor pair of gill filaments2) Numerous Lamella (primary and secondary) – thin epithelial cells3KEY: Counter Current Exchange System – blood and water flowing in opposite directions4Afferent, Efferent, Primary and secondary lamella and WATER and Blood5KEY: Counter Current Exchange System – blood and water flowing in opposite directionsNeed continuous supply of O2 rich water = Ventilation of gillsMoving Water Across Gills:Pump with buccal and opercular chambers; a) water enters mouth by buccal expansion; b) water accelerated by simultaneous contraction of buccal and expansiuonof opercule: Reverse = coughSharks, skates and rays – use flaps of skin to create current6What if Low Oxygen?Fish will increase:a) frequency of ventilation (buccal and opercule); b) increase ventilatory stroke volume.Accessory Ventilation- Gulp water at surface – higher O2 due to diffusion- Breath Air (Gills collapse)- Gill modifications – Clarius batrachus (walking catfish); thick lamellae; branched structures- Skin – well vascularized skin – eels – (Anguilla anguilla)- Mouth – obligate air breathers, vascularized buccal regions w/ surface convolutions and papillae; gills degenerate – drown if forced immerse- Gut – Plecostomus, etc. – Swallow air, O2 in gut – CO2 out at gills.- Modified Swim Bladder – Lungfish – need to surface for air; Other with modified = Bichir, Amia (Bowfin); Lepisosteus (Gars)Air Breathing Fish7Gas Transportation:Hemoglobin; Binds O2 release at tissue;Some fish one type, others (Salmon & Suckers) have backupHemoglobin and Oxygen Disassociation Curves – percent saturation vs. partial pressure Oxygen (pO2)Bohr Effect (lower affinity for O2 in acid due to configuration of O2 binding sites –requires higher pO2 for saturation)Root Effect (never get saturated at lower pH due to `extreme change in configuration)CO2 lowers pH – forms carbonic acid (H2CO3)Respiratory surface – CO2 released, decrease H2CO3, Ph up – O2 binds easierTemperature - Affinity O2 decreases as Temperature increasesWhy cold water fish die at increased temperatures; Tunas and sharks not effected by temperaturesDifferent fish also show different affinities – toadfish to left of mackeral makes it better for low oxygen environments8Bohr Effect - releases O2 from hemoglobin due to decreased affinity (pH)Lower affinity for O2 in acid due to configuration of O2 binding sites – requires higher pO2 for saturationRoot - never get saturated at lower pH due to extreme change in configuration)9Buoyancy and Gas BladdersNeutral Buoyancy – minimize cost of everything1) Incorporate large quantities of low-density compounds a) Body 85% water – ½ salinity = lighter – Mola mola;b) Sharks - Lipids – specific gravity .9 & oils –hydrocarbon squalene (s.g. .86 in livers; Also cartilaginous skeleton = 1.1 s.g. vs 2.0 bone v. 1.05-1.1 tissuesc) Teleosts – Sablefish, Medusa fish (pelagic), Rock fish – have triglycerides (low density oils) – in deep water greatly reduced skeletal elements and muscles; Problems – energetically problematic and hard to respondBuoyancy and Gas Bladders2) Swimbladders - precise control of buoyancyUsed for hydrostatic balancing, sound production and reception, respiration Two types:- A) Physostomous – connection via pneumatic duct between swim bladder and gut- Primitive – soft rayed teleosts; Herrings, salmonids, eels, osteoglossids, mormyrids, pikes, cyprinids, characins, catfish.- Gulp air through duct by force - Mainly shallow water – each 10 m need 2X air to inflate- Release air by “gass-puckerflex” gas spitting reflex – relax sphincter and contract swim bladder wall.10Buoyancy and Gas Bladders2) Swimbladders - Two types:B) Physoclistous = ClosedFrees fish from surface – over 2/3 of teleosts are physoclistous, some lost Scombrids (tunas) and Darters and SculpinsRelated to ecology of fish – benthic fish = little or no; swift vsslow moving water; vertical migrationsGas Bladders – usually four layers; 1) outer = densely woven elastic fibers2) next = loosely organized fibers3&4) inner two = smooth muscle and epithelium quanine crystals just below outer elastic fibersGas SecretionRete Mirabile = (Wonderful Net) = tight bundle of afferent and efferent capillaries; Source of gas; But need to increase pressure – How??Three phenomena 1) Effect of acidification on hemoglobin’s ability to hold O22) Reduced solubility of gases in solution as lactate and hydrogen ions increase = salting out effect3) Efficiency of countercurrent exchange11Gas SecretionWhat is mechanism?Gas Gland secretes lactic acid into blood, lowers pH.Increase partial pressure of CO2 by releasing CO2 from bicarbonateBohr Effect –Root Effect = decrease capacity of hemoglobinMore O2 into blood – diffuses into lumenGreater the length, the more efficient transferDeflation = diffusion of gas into