BIO 358 1st Edition Exam 3 Study Guide Lectures 15 25 Lecture 10 Dive Physiology Balanced Growth Equation Ingestion Somatic Growth Reproductive Growth Respiration Egestion Excretion Work Energy In Energy Out or used Metabolic rate MR rate of energy usage measured as oxygen consumption rate Diving is Work Swimming foraging seeing food capturing food digesting food but the diving metabolic rate is equal to or less than the resting metabolic rate Why Access to Oxygen Surface and access to prey underwater needed for survival all of marine mammals things for life other than oxygen are done in a breathold apnea Two alternate paradigms for diving 1 Elsner s view Defense against asphyxia the moment an animal takes a breath hold it is taking a slow and stead path to asphyxia 2 Kooyman s view Most dives are aerobic marmams have plenty of onboard oxygen store using oxygen very efficiently Irving and Scholander 1930 s Pinniped restrained and submerged the head underwater Results Dive Reflex 1 Extreme bradycardia 90 reduced 2 Ischemia highly reduced blood flow to peripheral tissues blood preferentially shunted to brain and heart vital organs 3 Reduced aerobic metabolism 4 Increase in anaerobic metabolism in the body PROBLEM Animal had no control Anaerobic metabolism Used with no oxygen supplies uses anaerobic pathways produces less energy and a build up of lactic acid toxic metabolite Lactic acid indicator of anaerobic metabolism can be measured in a blood sample Elsner 1960 trained voluntary dives phocids and bottlenose dolphins different results Dive response range of responses depending on the length of the dive highly variable range of physiological responses that a marine mammal invokes on a dive Weddell seal Large 2 5 3 m 400 kg Antarctic distribution never hunted found more inland than other species not afraid of humans have specialize teeth to ream out holes in the ice perfect for an experiment Kooyman Grabbed a seal and drove it far inland to a researcher made ice hole where humans could survive control where the Weddell seal comes up for air with an ice hole Attached time These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute depth recorder TDR invented by Kooyman and Gentry to measures depth worn as a pack on the animal and took blood samples and measured oxygen used by placing a dome over the hole Results Weddell seal dive profile shallow exploratory dives 20 minutes and deep dives some very long 30 60 minutes 400 700 meters dives were episodic meaning there was a break during the dive at the surface before it goes on its next dive Were they aerobic Where oxygen is stored Lungs blood hemoglobin muscle myoglobin smaller than hemoglobin but grabs onto oxygen with a heme group Where is it stored in a diving marine mammals Lungs NO well not a lot blood YES blood volume is increased increased hematocrit of Red Blood Cells i e human hematocrit 30 45 weddel seal 60 Muscle YES increased myoglobin content Aerobic Dive Limit ADL Maximum breath hold time possible without an increase in lactic acid during or after a dive lactic acid is evidence of anaerobic metabolism ADL Body mass X O2 mass Diving MR Total onboard oxygen rate of oxygen usage unit minutes ADL for Weddell Seal 24 minutes dives longer than 20 30 minutes lactic acid in blood anaerobic Diving MR equal or less than resting What are they doing when there is no human interaction strapped TDRs on 22 Weddell seals brings back TDR s and analyzes data Results in the wild only 3 8 of dives are longer than the ADL when they go over their ADL they have to spend extended time at the surface to recover and get rid of lactate debt Weddell seals in the wild are NOT on the verge of Asphyxia Reasons to stay within the ADL Longer foraging time able to spend more time at depth Reasons to go anaerobic Abundant food source an Ice hole freezes or there s another seal in your ice hole Northern Elephant Seals Mirounga angustirostris very large males 4 5 m 3600 kg spend 1 month to moult and 1 to breed other 10 months at sea PELAGIC ANIMAL Burney Le Boef and Dan Costa Elephant Seal Dive Profile Prolonged Continuous diving diving ALL of the time 3 dives per hour each 20 minutes only 2 to 3 minutes of any hour at the surface spend 90 of their life at sea UNDERWATER submarine mammals sleep underwater Elephant Seal Dive Record 140 minutes 1500 meters Elephant seal ADL has never been directly measured estimation based on resting MR 30 mins for small females and 50 mins for large meals However elephant seals routinely dive longer than the calculated ADL suggesting either diving MR is lower than resting or enhanced ability to utilize on board O2 they can handle really low oxygen levels Evidence that dives are aerobic dive profile of elephant seals does not show recovery time at the surface Reasons for deep diving 1 Feeding gain about 1 kg per day 2 predator avoidance avoid great white sharks or killer whales 3 energy conservation diving MR lower than or equal to resting MR The many unanswered questions How do you find your prey how do you determine how deep you are How do you know where to go or how to go home Missed Class Assignment What four species common and scientific names did Williams and colleagues investigate Weddel Seal Leptonychotes Weddellii Northern elephant seal Mirounga angustirostris bottlenose dolphin Tursiops truncatus Blue whale Balaenoptera musculus They investigated behavioral strategies to improve energetic efficiency What techniques did the authors use to measure these species swimming modes They attached video cameras to free ranging animals and observed the stroke frequency diving periods and glide sequences and time depth recorders What is the overall pattern of swimming during a dive for these species Be able to discuss stroking vs gliding Fig 1 Weddel Seal stroked for about 100 meters then glide till about 400 meters and then stroke to get back to the surface Northern elephant seal stroke for the first 100 meters glide down to about 325 meters and then stroke to about 50 meters and then glide to the surface Bottlenose dolphin stroke for 70 meters and then glide to 110 meters and then stroke to 10 meters and glide to surface Blue whale stroke for the first 30 meters glide till 80 meters stroked down a little and then up to 40 meters with a little more stroking and then gliding to the surface At what depths do these species begin to