Chapter 9 Marine Ecology ©2003 Jones and Bartlett Publishers

 Quiz at beginning of lab period. Not at end of lecture. Ask me questions!

 Ecology - From greek ‘oikos’ meaning ‘house’. -The study of organisms ‘at home’. -More formal definition: The science of the interrelationships between living organisms and their environment (Odum). 9Marine Ecology

There are two major marine provinces: the benthic (bottom) and the pelagic (water column). The benthic environment is divided by depth into the following zones: –Littoral(<1%)intertidal- between the tides –Sublittoral (8%)low tide to edge of cont. shelf, 0-200m –Bathyal(16%)200 – 2000 m –Abyssal(75%)2000 – 6000 m –Hadal(1%)> 6000 m Marine Provinces

There are two major marine provinces: the benthic (bottom) and the pelagic (water column). The pelagic environment is divided by depth into the following zones: –NeriticShallow water overlying cont. shelves. –OceanicDeep water beyond shelf edge. Epipelagic (3%) 0 – 200 m surface, illuminated Mesopelagic (28%) 200 – 1000m Bathypelagic (15%) m Abyssalpelagic (54%) 2000 – 6000 m Hadalpelagic ( 6000 m In trenches. Marine Provinces

Light Zones Yet another way to classify the ocean Photic zone –light is sufficient for photosynthesis –to 100 (or 200 m) Dysphotic zone –light is too weak for photosynthesis –twilight zone –< 5% sunlight –100 to 200 m Aphotic zone – no light

In 1735 Linnaeus developed the taxonomic classification used in zoology. Kingdom (Metazoa) - Phylum (Chordata) - Class (Mammalia) -Order (Primate) - Family (Hominidae) -Genus (Homo) -species (sapiens) The scientific name of an organism consists of its genus name (capitalized) combined with a species name (lower case), both italicized or underlined. Ex. Homo sapiens Classification of Organisms

The five major kingdoms in the ocean are: Monera: single-celled organisms without nucleus (Prokaryotes) Protista: single-celled organisms with nucleus (Eukaryotes). Fungi : important in decomposition and recycling. Metaphyta: plants that grow attached to the sea floor. Metazoa: all multicellular animals in the ocean. Classification of Organisms

Marine organisms can also be classified by lifestyle. Plankton –float passively, can swim vertically, but not against currents. They can be divided into phytoplankton (plants) and zooplankton (animals). Nekton –active swimmers (marine fish, reptiles, mammals, birds and others) Benthos –live on the bottom (epifauna) –within the bottom sediments (infauna) Some organisms cross from one lifestyle to another during their life, for example being planktonic early in life and benthic later (seaweeds, clams, etc). Classification of Organisms

Epiflora Epifauna Infauna

Classification of Organisms Flounder: Benthos or nekton???

Classification of Organisms Clam: Benthos or plankton???

Classification of Organisms

Classification of Organisms: The 5 Kingdoms Monera: bacteria -no internal cell membranes -planktonic or benthic -recycle organic material -some photosynthetic Blue-green algae (photosynthetic) heterotrophic

Classification of Organisms Protista: foraminifera, diatom, seaweed -planktonic or benthic - internal membranes - planktonic, benthic, eat or photosynthesize Foram. Diatom Seaweed

Classification of Organisms Fungi: single and multi-cellular -decomposers -planktonic or benthic

Classification of Organisms Metaphyta: multi-cell plants -primary producers in intertidal -benthic eelgrass Salt marsh Mangroves Not seaweeds!

Classification of Organisms Metazoa: multicellular animals - planktonic (jellyfish, shrimp), nektonic (fish,whales), and benthic (crabs, worms). Fish jellyfish whales

Ecosystem is the total environment including the biotic (living) and abiotic (non-living) physical and chemical aspects. –Examples of marine ecosystems: Salt marshes Mangrove Intertidal neritic Benthic Or, global ecosystem. Basic Ecology

Environmental factors in the marine environment include: -temperature -salinity -pressure -nutrients -dissolved gases -currents -light -suspended sediments -substrate (bottom material) -river inflow -tides and waves. Basic Ecology

Temp ranges in ocean between -2 to ca. 40 C. More than 90% of ocean is <5 C. Can control distribution, degree of activity, and reproduction of an organism Temperature controls the rate of chemical reactions within organisms, thus their rate of growth and activity –Most organism’s are ‘cold-blooded’ or ectothermic. –10 o C rise in temperature, doubles the activity Temperature:

Temperature Effects: barnacles more activity with higher temperature

Temperature Effects: clam harvest

Salinity Effects Can control the distribution or behavior of organisms. –Epipelagic more S-tolerant than mesopelagic organisms. Nearshore organisms more tolerant to salinity changes. –Large S-variations results in tolerant organisms. –Sessile benthic can close shells. Availability of dissolved elements (calcium and silicon) can limit an organism’s ability to construct shells. –Silica depletion results in reduction in diatom production. Marine organisms’ body fluids have the same proportion of salts than sea water. –Sometimes more salt, sometimes less, than surrrounding sea. –Diffusion, osmosis and osmoregulation.

Salinity Effects: Diffusion Definition: physical process whereby molecules move from areas of higher concentration to areas of lower concentration.

Salinity Effect: Osmosis Definition – Diffusion of water molecules through a semi-permeable membrane. Remember: “salt sucks”

Osmoregulation by Marine and Freshwater Fish Marine fish must control osmotic water-loss or fish will dehydrate. Freshwater fish must control osmotic water-gain or fish will swell & explode.

The pressures exerted by a column of water surrounding an organism. –10 m column of water = 1 atm. Hydrostatic Pressure

3 Styrofoam cups sent to 5000 meters depth.

Hydrostatic Pressure How do deep-dwelling animals survive high pressures? Answer: many have no body cavities containing gasses.(Gasses are more compressible than liquids). Fish use gas-filled swim bladders to regulate depth.

Plankton include plants (phytoplankton) and animals (zooplankton). More than 90% of marine plants are algae and most are unicellular and microscopic. Selective Adaptive Strategies: Plankton

Phytoplankton photosynthesis

Selective Adaptive Strategies: Plankton size- one way plankton defy gravity to stay suspended in photic zone

Some Characteristics of Phytoplankton Size: 0.5 micron to 1 mm Eukaryotes and prokaryotes (bacteria) Some motile with flagella (dinoflagellates) some not (diatoms) Contain chlorophylls and other pigments for photosynthesis. Silica, Calcium carbonate, or no shell. Responsible for ½ oxygen production on Earth. Major sink for atmospheric CO 2. Major types: Diatoms (require silica for growth) Dinoflagellates (some toxic; symbiotic with corals) Synechococcus and Prochlorococcus (tropical)

Some Diatoms

General Diatom Structure Chloroplast

Diatom Cell Division

Phytoplankton “blooms” Diatoms and other phytoplankton can divide many time per day producing large blooms that are sometimes visible from space.

Zooplankton include the copepods and foraminifera. Copepods are small herbivores (plant- eating organisms) that filter diatoms from the water. Foraminifera are single-celled animals which build shells of calcium carbonate. Zooplankton

Zooplankton include the copepods and foraminifera. Zooplankton Live foraminifera (size ca. 0.5 mm) Copepod (size ca. 1-5 mm)

Selective Adaptive Strategies: Copepod feeding

The morphology of fish has evolved to allow them to move through the water easily. The fish’s body must overcome three types of drag (resistance) –surface drag –form drag –turbulent drag. Selective Adaptive Strategies: Fish

Surface Drag: Friction between the moving body and surrounding fluid. –Decrease surface area, decrease surface drag. –Sphere has least surface area for given volume, so sphere is best shape for reducing surface drag. –But fish aren’t shaped like an orange, so what else is important? Selective Adaptive Strategies: Fish

Form Drag: Proportional to cross-sectional area of fish’s body. – larger x-sectional area, more water needs to be ‘pushed aside’. –Narrow pencil-shaped body best for moving through fluid. –But not all fish are shaped like pencils either, so what else is important? Selective Adaptive Strategies: Fish

Turbulent drag: friction arising from turbulent eddies of water that form behind an object moving through a fluid. – Reduced by having classic ‘torpedo shape’. –Torpedo shape displaced water with minimal disturbance. –What fish is most superbly adapted for swimming at high speeds for extended periods of time?? Selective Adaptive Strategies: Fish

The Tuna!!

Selective Adaptive Strategies: Aspect ratio The speed of a fish is related to the shape of its caudal fin: Aspect ratio, AR = (Caudal Fin Height) 2 /Caudal Fin Area High-speed cruisers Quick, darting movement

Selective Adaptive Strategies: Fish classification scheme based on locomotion

Intertidal benthic communities generally are arranged in distinctive bands, termed vertical zonation. Zonation reflects the amount of time the area is submerged and the ability of the organism to survive the stress of exposure. Benthonic communities also vary in response to substrate (bottom material). Some organisms are adapted to rocky, sandy, or muddy sea bottoms. 9-5Selective Adaptive Strategies

Banded Benthic Communities

A complex interaction among kelp, sea urchins, and sea otters controls the kelp community. Macrocytis is a brown algae that grows up to 40m long in extensive beds on North America’s Pacific continental shelf. Sea urchins feeding on kelp detach them from this holdfast and devastate the kelp beds. The Ocean Sciences: Ecology of the Giant Kelp Community

Kelp Forest Ecology

Sea otters feed on sea urchins and control the size of their population. –Where sea otters abound, sea urchins are few, kelp beds thrive and sea otters feed mainly on fish. –Where sea otters are few, sea urchins abound and kelp bed are thin. Sea otters then mainly eat sea urchins. The Ocean Sciences: Ecology of the Giant Kelp Community

2-5Geophysical Surveying THE END

Surface Drag: Friction between the moving body and surrounding fluid. –Decrease surface area, decrease surface drag. –Sphere has least surface area for given volume, so sphere is best shape for reducing surface drag. –But fish aren’t shaped like an orange, so what else is important? Selective Adaptive Strategies: Fish

Form Drag: Proportional to cross-sectional area of fish’s body. – larger x-sectional area, more water needs to be ‘pushed aside’. –Narrow pencil-shaped body best for moving through fluid. –But not all fish are shaped like pencils either, so what else is important? Selective Adaptive Strategies: Fish

Turbulent drag: friction arising from turbulent eddies of water that form behind an object moving through a fluid. – Reduced by having classic ‘torpedo shape’. –Torpedo shape displaced water with minimal disturbance. –What fish is most superbly adapted for swimming at high speeds?? Selective Adaptive Strategies: Fish