Introduction to Marine Ecology Physical limiting factors light, temperature, salinity, nutrients, gases variation within the ocean: depth and geography Marine habitats: where to make a living Marine feeding types: how to make a living Ecology The study of the relationships among physical and biological aspects of the environment. how organisms adapt to and alter their environment factors that control distribution and abundance of organisms How do organisms meet their needs? Physiological tolerances, food, mates, Ecological communities and ecosystems Ecological community: Interacting organisms living in a specific habitat Marine examples: coral reef, mangrove, estuary, intertidal Community ecology studies the distribution and abundance of species in a community, and their interactions E.g. patterns of species richness and productivity; processes such as predator-prey interactions and succession Ecosystem ecology studies how the biotic and abiotic components of an ecosystem interact E.g. how climate, nutrients, etc. influence species and their interactions - and how the biota influence the physical and biogeochemical aspects of the system Limiting factors Some aspect of the environment that limits an organism s distribution. Physical limiting factors temperature, salinity, nutrients, light... Biological limiting factors competition, predation, herbivory 1
Limiting factors Physical factors: light penetration Coastal ocean Open ocean Light penetrates deeper in clear, open ocean than it does in turbid, coastal water Physical factors: light and light penetration Photic zone: depth to which light penetrates Defines zone of photosynthesis and primary productivity (base of the food web). Aphotic zone is below photic zone. Most of the ocean is dark. Dysphotic zone is very low light; too little for photosynthesis Photosynthesis 6 CO 2 + 6 H 2 O sunlight C 6 H 12 O 6 + 6 0 2 glucose Respiration C 6 H 12 O 6 + 6O 2 6 CO 2 + 6 H 2 O + Energy 2
Light limitation Example: Wha -2891 m deep -Monterey Canyon Confines most productivity to upper 100-200 m Organisms below this have to be creative in how they obtain food Feed on detritus Chemosynthesis at black smokers New species of worm that feeds exclusively on whale carcasses Roots that extend into bone Massive egg sacs, and dozens of microscopic males (larval, with copious sperm) living in the female Why?? -Worms and sea cucumbers http://www.mbari.org/news/news_releases/2004/whalefall.html Limiting factors: temperature Temperature affects metabolic rate: the rate at which reactions proceed in an organism Metabolic rate doubles for every 10 C increase in body temperature Most marine organisms are ectothermic same body temperature as the surrounding water. clams, shrimp, most fish... Some marine organisms are endothermic - constant and usually higher body temperature than the surrounding water. marine mammals, birds, some tuna and sharks. Limiting factors: temperature Endotherms can tolerate a broader range of external temperature than ectotherms. But endotherms require more energy (food) than ectotherms. 3
Temperature affects activity Barnacle cirri beat faster at higher temperature Faster beat = more efficient feeding Temperatures in the ocean Extremophiles beyond this range - submarine hot springs - in polar ice: antifreeze glycoproteins in blood Limiting factors: salinity Normal marine salinity is 35 Too high or too low is damaging Low diversity in estuaries (low salinity) Low diversity in areas of high evaporation (high salinity) Maintaining salt balance is critical - organisms do this by: Diffusion passive movement from areas of high concentration to low concentration Osmosis diffusion of water through a membrane Active transport active removal of substances from an area of low concentration to high concentration Diffusion Passive equalizing of concentrations Substance (or temperature) diffuses from high to low concentration, equalizing them Examples: diffusion of gases into ocean, into cells; diffusion of nutrients into (and wastes out of) phytoplankton 4
Osmosis Type of diffusion that equalizes water concentration Water (but not salts) flows thru cell membranes into region of higher salt concentration Can create osmotic stress if cell is moved into region of contrasting salinity Salt water is dehydrating; it removes water from within the cell. Limiting factor - Pressure High pressure in deep: makes life impossible? No! Most organisms do not perceive this No gases in body (gases are compressible) Fishes with gas bladders are adjusted for this pressure Die (explode) if brought rapidly to surface Can adjust to move up and down gradually on their own Limiting factors: dissolved nutrients Required for the production of organic matter Required for photosynthesis - the base of the food web Limiting nutrients: Nitrates NO 3 - Phosphates PO 4 - Sometimes, Fe (iron), Si (silicon) fertilizers Global nitrates Low in the photic zone, High in upwelling areas surface 200 m 1,000 m Slides/ global nitrate 5
Global phosphates Low in the photic zone, High in upwelling areas surface 200 m Slides/ global phospho rus Fig/ nutrient/energy cycling 1,000 m Ocean has a tremendous variety of physical habitats! Fig/ typical ocean profiles 6
Marine habitats: Where to make a living Pelagic zone: living in the water neritic zone: nearshore, over the continental shelf oceanic zone: beyond the continental shelf Benthic zone: living on the bottom littoral - between high and low tide intertidal sublittoral - out to edge of continental shelf bathyal - continental slope abyssal - abyssal plain hadal - deep sea trenches Marine lifestyles Planktonic: drift almost passively; cannot counteract a current. phytoplankton (plants) zooplankton (animals) Nektonic: active swimmers: fish reptiles mammals birds Benthic: Live on the bottom Epifaunal Infaunal An organism can change modes through its lifetime, e.g. larvae or juvenile vs adult Need ways to stay in photic zone Small mass = slow settling High friction = more drag Plankton 7
Benthic Habitats infaunal, epifaunal Infauna Animals that burrow into soft substrates (sand and mud) Challenges include: Displacing sediment (digging/burrowing) Constructing structurally sound burrows Protecting tissues from abrasion Benefits include: Protection from predators, wave energy, desiccation What s the best way to swim? Minimize drag Be fast Accelerate Cruising Be maneuverable How to swim fast? Speed of a fish is dependent upon: body length (long = fast) beat frequency (more beats/sec = faster) the aspect ratio of the caudal fin (high = fast) Aspect ratio is the ratio of the square of the caudal fin height to caudal fin area: AR = (Caudal Fin Height) 2 /Caudal Fin Area Faster Slower 8
Note specialists vs generalists Marine habitats: how to make a living Primary producers: Autotrophs (make own food) Phytoplankton - floating photosynthetic algae Primary producers: autotrophs Benthic macroalgae Marine habitats: how to make a living Sea grass Marine habitats: how to make a living Primary producers: autotrophs Suspension (filter) feeders: filter water for food: pelagic suspension feeders: zooplankton benthic suspension feeders:many mollusks, sponges, baleen whales 9
Jellyfish Whale shark (http://en.w ikipedia.org/wiki/image: Whale_shark_Georgia_aquarium.jpg Yellow tube sponge http://cas.bellarmine.edu/tietjen /images/phylum_porifera.htm Copepod Slide/ sponge - colonial Marine habitats: how to make a living Primary producers: autotrophs Suspension feeders: filter water for food Benthic grazers: scrape the bottom for algae: sea urchins, snails, nudibranchs, manatees 10
Sea urchin Gastropod (snail) Nudibranch Marine habitats: how to make a living Primary producers: autotrophs Suspension feeders: filter water for food Benthic grazers: scrape the bottom for algae Benthic deposit feeders: eat sediment: many worms, crabs, some sea urchins, some fish Manatee Heart urchin Marine habitats: how to make a living Primary producers: autotrophs Suspension feeders: filter water for food Benthic grazers: scrape the bottom for algae Benthic deposit feeders: eat sediment Predators: eat other animals: sharks, many fish, dolphins, octopus, killer whales, barnacles, corals Primary, secondary, tertiary... 11
Shark Barnacle Frogfish (camouflaged) Orca Coral polyps http://www.shiftingbaselines.org/ blog/archives/2005_11.html Tuna http://en.wikipedia.org/wiki/im age :Montastrea_cavernosa.jpg Octopus 12