The Marine Environment

1. The Marine Environment How physical and chemical properties of water affect life in the sea The Marine Environment

2. Salinity • Seawater contains a variety of dissolved solids • Solutes • Salinity is measured: • Conductivity of Cl- • Refractometer The Marine Environment

3. How Salinity Affects Marine Organisms • Most marine animals are adapted to a narrow salinity range • Changes is salinity affect organisms through osmosis • Hyperosmotic solution - water will flow into it across a semipermeable membrane • Hypoosmotic solution - water will leave the solution The Marine Environment

4. Temperature • At lower latitudes there is a capture of heat and at higher latitudes there is a loss of heat • This creates a temperature gradient for surface waters • Surface waters will fluctuate wildly at the mid-latitudes and almost remain constant at the poles and equator The Marine Environment

5. Temperature Regulation • Homeotherms(Endothermic) - organisms which regulate their internal body temperature regardless of the environment • Poikilotherms(Ectothermic) - organisms which have an internal body temperature that conforms to the environment The Marine Environment

6. Temperature Stratification • Thermocline is an area in the water column of rapidly changing water temperature • Thermoclines are most prominent during the warmer months due to solar radiation and weak mixing • After the thermocline the water is an almost constant temperature The Marine Environment

7. Dissolved Gases • Dissolved Gases • For living things the three most important dissolved gasses are oxygen (O2), carbon dioxide (CO2) and nitrogen (N2) • The amount of a given gas that can dissolve decreases with an increase in temperature • The amount of oxygen in a body of water depends on: • Mixing with the atmosphere • Respiration • Photosynthesis Sunlight + 6H20 + 6CO2 C6H12O6 (Glucose) + 6O2 The Marine Environment

8. Oxygen Consumption • Aerobic respiration • Respiration in the presence of oxygen • Anaerobic respiration • Respiration in the absence of oxygen The Marine Environment

9. Seawater becomes denser as it gets saltier, colder or both Halocline and pycnocline are areas of the water column where salinity and density change rapidly Methods for measuring seawater temperature CTD’s XBT (expendable bathythermograph) Niskin bottles (use reverse thermometers and messengers) Temperature over a large area can be taken using satellites (only surface temperature) Drifting or moored gear Data collected is used to get a picture of the water column Density, Salinity, and Temperature Relationship The Marine Environment

10. Methods for measuring Temperature Niskin Bottles Satellite Imagery The Marine Environment

11. Light • Light is crucial for photosynthesis and is strongest in the surface waters • Light attenuates with depth in an exponential fashion • UV light can be damaging to the proteins and DNA of many surface organisms • Effective light penetration can vary from 10-1,000m.) The Marine Environment

12. Turbidity and Light Penetration • Turbidity • The amount of solid particles suspended in the water column • Important since plants and algae need light for photosynthesis • Increase turbidity can decrease the amount of light which effectively penetrates • Large concentrations of phytoplankton can decrease light penetration (greenish tint) The Marine Environment

13. Pressure • Animals that live on land or sea level are at 1 atm (14.7 psi) • With an increase in depth of 10 meters (33 ft) pressure is increased by 1 atm. • Gas filled structures will shrink or collapse with depth • At the ocean’s avg. depth (3,700 meters) pressure is 2.7 tons per square inch The Marine Environment

14. Properties of Water • Water is more dense and viscous than air • Since it is a more supportive medium there is no need for a strong supportive skeleton • An important consideration when we discuss sinking rates and movement through water Surface tension The Marine Environment