CHAPTER 12 Marine Life and the Marine Environment

CHAPTER 12 Marine Life and the Marine Environment

Overview • More than 250,000 identified marine species • Most live in sunlit surface seawater • Species success depends on ability to • Find food • Avoid predation • Reproduce • Cope with physical barriers to movement

Classification of living organisms • Three domains of Life • Archaea • Prokaryotic, includes “extremophile” bacteria • Bacteria • Prokaryotic, includes what used to be in Kingdom Monera • Eukarya • Eukaryotic cells • Includes Protists, Fungi, Plants, and Animals

Archaea • Bacteria - Prokaryotic cells • Cell wall differs from those bacteria in Domain Bacteria • Includes extremophile bacteria • Acidophiles • Halophiles • Thermophiles • Etc. • These bacteria are found to chemosynthesize in hydrothermal vents

Bacteria • Bacteria – prokaryotic cells • Cell wall made of peptidoglycan • Includes Staphylococcus, Bacillus, Vibrio, Pseudomonas, etc. • Only a very small % of bacteria are pathogenic • Bacteria are very important in things like nitrogen cycle, decomposition, food making, etc. • Cyanobacteria are photosynthetic bacteria

Archaea and Bacteria • Most numerous organisms on Earth • Think about how much bacteria lives just on you • Viruses are thought to out number bacteria but if you are just talking about “live” organisms then bacteria are the most numerous • Simplest of organisms • But, can live in every thinkable habitat, even those once thought to be unsuitable to life, very successful

Now we will talk about Domain Eukarya • Includes protists, fungi, plants, animals

Eukarya - Protists • Algae • Photosynthetic • Can be unicellular, colonial, or multicellular • Multicellular - “seaweed” – kelp, sargassum, sea lettuce • Unicellular – phytoplankton, produce majority of oxygen in atmosphere, can cause red tides • Protozoans • Heterotrophic • Unicellular • Amoeba, paramecium

Eukarya - Fungi • Heterotrophic • Secrete enzymes and absorb nutrition • Since they are heterotrophic, they are more closely related to animals than to plants • Multicellular (mold) or unicellular (yeast)

Eukarya - Plants • Autotrophic, multicellular • Many plant species cannot tolerate saltwater • Very few species grow in/near ocean • Sea grasses • Mangroves • Dune plants

Eukarya - Animals • Heterotrophic, multicellular, have motility at some point in life cycle • Wide variety • From simplest of animals (sponges) to most complex (mammals)

Viruses • Acellular entities • Are they “alive”??? • Do not have the machinery for life processes, have to take over host cell • The ultimate “parasites”

Taxonomic classification • Systemized classification of organisms • Kingdom • Phylum • Class • Order • Family • Genus • Species • Fundamental unit • Population of genetically similar, interbreeding individuals

With new molecular methods (comparing DNA sequence and amino acid sequences of certain proteins), traditional taxonomy is changing • Taxonomists are discovering new relationships between species • Molecular data gives a clearer picture of relatedness as opposed to the traditional ways of classifying organisms: • Morphology, embryology, behavior, habitat, etc.

Classification by habitat and mobility • Plankton (floaters) • Nekton (swimmers) • Benthos (bottom dwellers)

http://i.ehow.com/images/GlobalPhoto/Articles/2110315/icephytoplankton-main_Full.jpghttp://i.ehow.com/images/GlobalPhoto/Articles/2110315/icephytoplankton-main_Full.jpg Plankton • Most biomass on Earth consists of plankton • Phytoplankton • Microscopic algae, Autotrophic • Zooplankton • Heterotrophic • Protozoans, tiny animals, larvae of larger animals • Bacterioplankton • Virioplankton • Viruses that infect bacteria and eukaryotic cells

Plankton • Holoplankton • Entire lives as plankton • Example is algae, protozoans, small microscopic animals • Meroplankton • Part of lives as plankton • Juvenile or larval stages in the plankton • Examples are lobsters, some fish species, etc. • Macroplankton • Large floaters such as jellyfish or Sargassum • Picoplankton • Very small floaters such as bacterioplankton

Nekton • Independent swimmers • Most adult fish and squid • Marine reptiles • Marine mammals

Benthos • Epifauna live on surface of sea floor • Infauna live buried in sediments • Nektobenthos swim or crawl through water above seafloor • Most abundant in shallower water

Hydrothermal vent biocommunities • Abundant and large deep-ocean benthos • Discovered in 1977 • Associated with hot vents • Bacteria-like archaeon produce food using heat and chemicals • “chemosynthesis instead of photosynthesis” http://bioinfo.bact.wisc.edu/themicrobialworld/Hydrothermal_vent.jpg

Number of marine species • More land species than marine species • Ocean relatively uniform conditions • Therefore, less adaptation required, less speciation • Don’t get this fact confused with # of individual organisms • There are fewer different species in the ocean but greater # of individuals • Majority of life on Earth lives in the ocean!! • Diversity in the ocean is high, also – think about different types of fish (seahorses to sharks, for example) • Marine species overwhelmingly benthic rather than pelagic • Most of these will be in shallow coastal benthic areas where there is light and a lot of primary productivity

Adaptations of marine organisms • Physical support • Buoyancy • How to resist sinking • Different support structures in cold (fewer) rather than warm (more appendages) seawater • Smaller size http://www.solaster-mb.org/mb/images

Adaptations to marine life • Appendages to increase surface area • Oil in micro-organisms to increase buoyancy • Over-time, if these organisms die and sink to bottom • Can become offshore oil deposits Fish egg with oil droplet Fig. 12.9 http://www.rpgroup.caltech.edu/~natsirt/aph162/webpages/dylanandco/lab1/image

Adaptations to marine life • Streamlining important for larger organisms • Less resistance to fluid flow • Flattened body • Tapering back end – fusiform http://www.wissenschaft-online.de/sixcms/media.php/591

Adaptations to marine life • Narrow range temperature in oceans • Smaller variations (daily, seasonally, annually) • Remember it takes longer to change water temp than air temp • Deep ocean nearly isothermal

Adaptations to marine life • Cold- versus warm-water species • Smaller in cooler seawater • More appendages in warmer seawater • Tropical organisms grow faster, live shorter, reproduce more often • More species in warmer seawater • More biomass in cooler seawater (upwelling) • Polar waters are much more productive (more plankton growth) than tropical waters

Adaptations to marine life • Stenothermal • Organisms withstand small variation in temperature • Typically live in open ocean • Eurythermal • Organisms withstand large variation in temperature • Typically live in coastal waters

Adaptations to marine life • Stenohaline • Organisms withstand only small variation in salinity • Typically live in open ocean • Euryhaline • Organisms withstand large variation in salinity • Typically live in coastal waters, e.g., estuaries

Adaptations to marine life • Extracting minerals from seawater • High concentration to low concentration • Diffusion • Cell membrane permeable to nutrients, for example • Waste passes from cell to ocean

Adaptations to marine life • Osmotic pressure • Less concentrated to more concentrated solutions • Isotonic • Hypertonic • Hypotonic

Adaptations to marine life • Dissolved gases • Animals extract dissolved oxygen (O2) from seawater through gills Fig. 12.15

Adaptations to marine life • Water’s transparency • Many marine organisms see well • Some marine organisms are nearly transparent to avoid predation

Adaptations to marine life • Camouflage through color patterns • Countershading • Disruptive coloring • http://www.youtube.com/watch?v=PmDTtkZlMwM http://theplasticocean.blogspot.com/2012_07_01_archive.html

Adaptations to marine life • Water pressure • Increases about 1 atmosphere (1 kg/cm2) with every 10 m (33 ft) deeper • Many marine organisms do not have inner air pockets • Collapsible rib cage (e.g., sperm whale)

Main divisions of the marine environment • Pelagic (open sea) • Neritic (< 200 m) and oceanic • Benthic (sea floor) • Subneritic and suboceanic • Another classification scheme: • Euphotic • Disphotic • Aphotic

Pelagic environments – Open ocean • Epipelagic • Mesopelagic • Bathypelagic • Abyssopelagic Fig. 12.19

Benthic environments – ocean floor • Supralittoral • Transition from land to seafloor • Subneritic(under neritic) • Littoral (intertidal zone) • Sublittoral(shallow tidal zone to 200m) • Suboceanic • Bathyal(200-4,000m) • Abyssal (4000-6000m) • Hadal(below 6000m) Fig. 12.19

CHAPTER 12 Marine Life and the Marine Environment

CHAPTER 12 Marine Life and the Marine Environment

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