8 Physical Factors that Affect Living Organisms KL Oceanography/Marine Biology Unit II: Ocean Planet

Physical Factors Light & Transparency Temperature Salinity Sound Hydrostatic Pressure Buoyancy Movement & Drag Currents Physical factor= any part of the physical environment that affects living things. Same idea as an Abiotic Limiting Factor

I. Light Zones & Transparency Light & Transparency Ocean water is fairly clear which allows sunlight to penetrate up to 200m (Photic zone) this is where photosynthesis takes place. Euphotic zone= top upper ½ of the photic zone, between 0~70m, is the area of greatest photosynthesis. Dysphotic zone= the lower ½ of the photic zone, between 70-200m. Light is present, but not enough to drive photosynthesis. Aphotic zone= from 200m and lower, where no light penetrates

I. Light & Transparency Transparency is limited by the number & shape of particles floating in the water. More particles=less light particles absorb light or scatter light. Particles= sediment, organisms (both alive and decaying) and other debris (garbage, plastic, etc.) The greater the transparency, the greater the amount of light energy can be absorbed  creating heat This causes the photic zone to be warmer than the aphotic zone

I. Light & Transparency Why is the ocean blue/green? Water absorbs colors at the red end of the visible spectrum Reflects the blue end of the visible spectrum water appears blue/green Most visible light is absorbed in the first 100m below sea level…even the blue wavelengths are absorbed by 300 m.

II. Temperature Temperature= measure of Kinetic Energy the chemical reactions that drive life processes are influenced by heat/Temp. The greater the heat, the faster the reactions can take place especially cellular metabolism (process of releasing energy to run cellular function). For cold blooded organisms, metabolic rates double for each 10ºC increase in water temperature Metabolic rate is proportional to how quickly an organism moves & reacts. Ocean temp. varies with depth and latitude Temp range is between 0º-30ºC

II. Temperature Ex> All Marine Fish and Invertebrates Ectotherms or Poikilotherms= cold blooded organisms their body temperature adjust to their surroundings Pro: Can slow down metabolism in colder water reduces the amount of food they need to consume Con: the colder the water; the slower the ability to move Somewhat habitat dependent Ex> All Marine Fish and Invertebrates

II. Temperature Ex> Marine Mammals Endotherms or Homeotherms= warm blooded organisms  they have a constant body temperature that allows for a constant metabolic rate, regardless of their surrounding temperature (for the most part). Pro: These organisms can live in a wider variety of temperatures and habitats than ectotherms Con: Endotherms demand a larger food supply and tend to have more efficient mechanisms for gas exchange. Ex> Marine Mammals

III. Salinity Salinity= cell membranes are sensitive to changes in salinity. Fluctuating salinity can physically damage membranes. Too much salt causes cell dehydration. Concentrated salt content can alter protein structure and function. See Osmoregulation notes

IV. Sound Sound = energy that travels in pressure waves… can only travel through matter. Sound travels about 1500m/s in water (5xs faster than air) and faster than light travels through water. Sound also bounces off suspended particles & other obstacles it encounters. Echolocation= the use of sound to sense and locate objects in the water… natural sonar. Used by toothed whales to determine an objects size, distance, density and position. Echolocation involves the emission of sound and reception of its echo.  The sound is emitted in the head region and focused by the melon.  The received echoes pass through special sound conducting tissue in the lower jawbone to the inner ear.

IV. Sound Echolocation is used by toothed whales, some pinnipeds (seals, etc), bats, and apparently, some humans!... Check this out: http://youtu.be/TB_yrWppP0c Ben Underwood was his name… if you are interested in checking it out for yourself

V. Hydrostatic Pressure Hydrostatic Pressure= the constant weight of the water column above a certain depth pressing down on an object or area. It differs from atmospheric pressure, which is the weight of the atmosphere pressing down on you or any other object. Water is heavier(more mass) than air, so hydrostatic pressure is greater than air pressure It “feels” heavier

Hydrostatic Pressure Atmospheric pressure exerts a force of 1kg/cm2 = one ‘bar’ = one atmosphere (‘ata’) Pressure inside and outside the animal equal out they have adapted to withstand this immense pressure. Pressure has been the biggest limiting factor to our exploration of the sea 100 m is the deepest depth experienced divers can typically withstand 20ATA

VI. Buoyancy Buoyancy= ability to float Archimedes’ Principle= objects immersed in liquid (or gas) are “buoyed” up by a force equal to the weight of the liquid (or gas) displaced. The density of seawater = the density of most living tissue; so organisms are buoyed up by a force that is equal to their own weight. Ex> 2000 kg whale displaces 2000 L of water in order to float

VI. Buoyancy How Do Marine Critters Avoid Sinking? Organic tissue like bone and shell often have > density than water, so organisms made of lots of bone or shell tend to sink without assistance. Marine organisms have developed adaptations to offset this problem: Swim (or gas or air) bladders- Balloon like structure allows bony fish to float with reduced energy spent Light cartilaginous skeletons sharks, rays, skates Production of oil in tissues sharks have huge oily livers Diatoms produce an oily substance to help them float

VII. Movement & Drag I’m slimy I’m fusiform I’m big & slow Water has a far higher viscosity than air, so it resists movement more than air. Drag= the resistance to movement caused by friction. It increases with viscosity and the speed, shape or size of a moving organism. Swimming organisms have developed adaptations to decrease drag: Very slow swimming speed Mucous secretions to lubricate organism so that it slips through the water Fusiform body shapes (torpedo shaped) streamlining by reducing turbulence I’m big & slow I’m slimy I’m fusiform

VII. Movement & Drag Viscosity affects microorganisms like plankton differently. Plankton are small in size, have little strength, yet have the need to stay suspended in the photic zone to survive. They have developed adaptations like plumes, filaments, ribbons, spines, and a variety of appendages to increase their drag to help them resist sinking.

VIII. Currents… more in Ch 9 Thermohaline Currents= deep ocean currents caused by density differences between temperature and salinity Circulate nutrients Create ocean conveyor belt Disperses both larvae and adult organisms to new habitats

VIII. Currents… last one! Surface Currents= currents generated by the pressure gradient force created by wind, the Coriolis effect and the rotation of the Earth Creates waves and tides Further circulates nutrients & disperses larvae