Marine Ecology • Biology – finally! • Why do we care? – – – – Fishing Water quality Diversity of species Medicines Ocean Habitats • Two major marine provinces – Benthic = bottom – Pelagic = water column BREAK Benthic Zone • Littoral or Intertidal zone – area between high and low tide • Sublittoral zone – from low tide to shelf break, ~continental shelf • Bathyal zone – shelf break to 2000 m • Abyssal zone – from 2000 to 6000 m • Hadal zone – sea floor deeper than 6000 m, trenches Pelagic Zone • Neritic zone – shallow water above the continental shelf • Oceanic zone – deep water of open ocean beyond the shelf break Oceanic Zones • Epipelagic – from surface to 200 m, the maximum depth of light penetration • Mesopelagic – between 200 and 1000 m, no light • Bathypelagic zone – between 1000 and 2000 m • Abyssalpelagic zone – between 2000 and 6000 m • Hadalpelagic zone – greater than 6000 m, trenches Percentage of Marine Habitats Zone Epipelagic Mesopelagic Bathypelagic Abyssalpelagic Hadalpelagic Sublittoral Bathyal Abyssal Hadal Depth (m) Pelagic 0-200 200-1000 1000-2000 2000-6000 >6000 Benthic 0-200 200-2000 2000-6000 >6000 Volume (%) 3 28 15 54 <1 8 16 75 1 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 Classification of Organisms • Kingdom – Phylum • Class – Order - Family - Genus - Species • Genus names are capitalized • Genus and Species are italicized – Homo sapiens Major Marine Kingdoms • Monera – Bacteria and blue-green algae • Protista – Single-celled organisms • Fungi – Multicelled organisms, which feed on decay and are not plants or animals • Metaphyta – Plants that are attached to the sea floor • Metazoa – All multicellular animals Monera • Bacteria – Important for decomposition, synthesis of organic compounds, and release of nutrients • Blue-green algae – Single cells, which lack a nucleus and convert ammonia and nitrogen into nitrates and nitrites Protista • Single celled organisms with a nucleus • Plants and animals – Foraminifera, coccoliths, diatoms, radiolaria dinoflagellates • Generate deep sea oozes – carbonates and silicates Fungi • Abundant in the intertidal zone • Not as diverse as on land • Important in decomposition Metaphyta • Plants that grow attached to the sea floor – Red, brown, and green algae – Advanced plants of salt marshes and coastal swamps • Only found in shallow areas where bottom is in the photic zone Metazoa • Mollusks – clams, oysters, snails, squid • Arthropods – barnacles, crab, shrimp • Analids – polychaete worms • Ctenophores – comb jellies • Brachiopods – lamp shells • Echinoderms – starfish, sea urchins, sea cucumbers • Chordates – fishes, sea turtles, seals and whales – o Whales, seals, and dolphins are mammals – warm blooded – Class Mammalia – o Sharks and fish - cold-blooded – Classes Chondrichthyes and Pisces – Sea turtles – Class Reptilia Metazoa • All multicellular animals Classification by Lifestyle • Plankton – animals that float and have no ability to propel themselves against the current – Phytoplankton • plants • Primarly productivity through photosynthesis – Zooplankton • Animals • Eat the phytoplankton – Some can migrate vertically • Nekton – active swimmers – Marine fish, reptiles, mammals, birds… – Larger ones can swim against currents – Distribution controlled by T and S Classification by Lifestyle • Benthos – Epifauna - live on the bottom – Infauna – live within the bottom sediments – Note: fauna signifies animals not plants • Plants are restricted to photic zone • Bacteria and animals survive at all depths, including trenches Classification by Lifestyle • One Problem: some animals start as planktonic or benthic or even nekton and change to nekton or benthic Basic Ecology • Ecosystem – The total environment including the biota (all living organisms) and nonliving physical and chemical aspects Basic Ecology • Environmental factors affecting life – – – – – – – – – – – – Temperature Salinity Pressure Nutrients Dissolved gasses Currents Light Suspended sediments Substrate (bottom material) River inflow Tides Waves Temperature Effects • 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 – 10oC rise in temperature, doubles the activity – Polar organisms grow slower, reproduce less frequently, and live longer than tropical organisms – Tolerance to variation in temperature varies greatly between species and within an organism’s lifespan – Temperature can indirectly control organisms by limiting their predators or restricting pathogens Temperature Effects • more activity with higher temperature Clams and Green Crabs • Salinity Effects • Can control the distribution of organisms and force them to migrate in response to changes • Availability of various dissolved chemicals (calcium and silicon) can limit an organism’s ability to construct shells • Epipelagic organisms are more tolerant to changes, since they are more accustomed to them • Marine organisms’ body fluids have the same proportion of salts than sea water, but lower salinity Diffusion and Osmosis • Diffusion – physical process whereby molecules move from areas of higher concentration into areas of lower concentration • Osmosis – movement of water molecules through the cell membrane from where salinity is lower to where it is higher – Can result in dehydration of surrounding water is more saline (saltier, higher salinity) – Can result in rupturing of the cell if surrounding water is fresher • Hydrostatic pressure – P=? gh – Gases are compressible, but water not Osmoregulation • Control of diffusion through the cell wall and the maintenance of sufficient body fluids • Marine organisms – Drink large amounts of water – Chloride cells extract and dispose of excess salt • Freshwater organisms – Don’t drink – Produce large amounts of dilute urine Selective Adaptive Strategies • Plants – 90% of marine plants are algae – Most unicellular and microscopic – Photosynthesis • Takes CO2 and nutrients and makes organic compounds, O2, and energy • Chlorophyll needed for photosynthesis – More dense than water and sink, but have evolved various methods to retard sinking • Increasing surface area slows down sinking because of frictional drag • Small size results in a better ratio of drag to mass • Porous shells and spines increase drag – Holdfasts – anchors that plants use to hold themselves to the bottom • Don’t bring in nutrients or water like the roots of land plants Diatoms • Thrive in cold, nutrient rich waters of polar region and inshore regions of mid-latitudes • Plankton bloom – – rapid reproduction – Often in spring • Single cell in siliceous shell shaped like a pillbox -silicates Selective Adaptive Strategies • Zooplankton – Copepods • Small herbivores (plant eaters) that filter diatoms from the water • Molt their outer skeleton as they grow • About the size of a grain of rice • Migrate vertically seasonally – Foramifera • • • • Single celled, microscopic organisms Calcium carbonate shells - Carbonates Benthic forms outnumber the pelagic Their shells are porous and protoplasm streams from inside the shell to engulf and digest food Copepods and Foraminifera Selective Adaptive Strategies • Fishes • Morphology of fish has evolved to allow them to move through the water easily Three types of Drag • Surface – Friction between the surface and the water – Reduced by reducing surface area – Sphere offers least surface drag • Form – Function of volume of water which must be displaced – Increases as the cross-sectional area increases – Needle or pencil shape has least form drag • Turbulent – Created around a body as it moves through a fluid – Reduced by having a blunt leading edge and a tapering end – Torpedo has least turbulent drag Speed in Water • Speed dependent on – Body length – Beat frequency • number of times the tail (caudal fin) sweeps back and forth in a unit of time – Aspect ratio of the caudal fin • AR = (caudal fin height)2/caudal fin area • Low aspect ratio – Tail is broad – Short, rapid acceleration and good maneuverability but lots of drag – Good for darting motion • High aspect ratio – Tail is narrow – Ideal for maintenance of high speed, bad for maneuverability Three Basic Body Types • Torpedo shape – Efficient, high speed cruising • Elongate – Rapid acceleration • Circular – High maneuverability Intertidal benthic Communities • Vary with the substrate (bottom material) – Rocky – firm, stable material for attachment, but prevents burrowing – Sandy – mobile and abrasive, but can be burrowed into – Mud – provides little support, but is easy to burrow through – Infauna dominate in sand and mud
