MAST382 EXAM 3
Egg laying (oviparous)
Broadcast spawning: fertilized eggs are released into the water column to be carried by currents to new suitable habitat (possibly more food, but have to release extra eggs) Brooding: fertilized eggs are carried by a parent until they can hatch (higher survival rate bc of parental care) - ex = Banggi cardinalfish holds eggs in mouth to protect them
Communication
Attract mates Locate prey Find suitable habitat
Formation and modifications of coasts
1. Erosional coasts- net loss of land - eroded by wave action, river or glacier-induced erosion - e.g., cliffs, rocky shores 2. Depositional coasts- net accumulation of land - sediment accumulation after being transported to the area in rivers and glaciers or by ocean currents and waves - e.g., deltas, mangroves, salt marshes, barrier islands, sand dunes
Coastlines are formed/modified when
1. sea level rises (coast added) or landmass subsides (coast lost) 2. land is added or removed - (deposition/erosion) Sea-Level Changes Eustatic - changes in volume of water (thermal expansion of water, melting glaciers) or volume of the basin itself (divergent margins). - Occur relatively uniformly worldwide Isostatic - local changes in sea level due to some other process (glacial rebound, sediment compaction)
Harmful Algal Bloom (HABs)
= excess nutrients and long water residence times combined with insufficient predators Some dinoflagellates produce toxins that are harmful as they go up the food chain Also lead to high bacterial respiration and anoxia or hypoxia → Fish kills, "dead zones" Excess nutrients and long water residence times combined with insufficient predators When HABs and zooplankton die-off, they are consumed by decomposers (bacteria, fungi) The decomposers use dissolved oxygen When dissolved oxygen depletes → Animal die-offs
Groins and Jetties
A groin is a wall built perpendicular to the beach from the backshore out to beyond the surf zone. Intended to block the longshore drift so that sand accumulates on the upcurrent side of the groin. Deplete sand supply to the beach on their downcurrent side, where severe erosion may occur. Alongshore current = Jetties (or groins) trap sediments from upstream to downstream Barrier island continues to retreat in segment adjacent to the segment along which shoreline erosion control is practiced.
Estuarine Circulation
Additional factors affecting fresh and seawater mixing: - wind-driven wave mixing - shape and depth of the estuary - friction between the moving freshwater and seawater layers - friction between the water and seafloor - the Coriolis effect
Coasts, Coastal Ocean, Estuaries
All 3 are operationally defined - Coast- from where the water meets the land inland to where there is no longer ocean influence on land. - Coastal ocean- the region between the land and the open ocean that is dominated by processes resulting from land-ocean boundary interactions. Includes the continental shelf, part of slope. - Estuary- partially enclosed body of water where freshwater from rivers mix with oceanic salt water.
Iron (Fe) as Micronutrient
All phytoplankton require Fe for photosynthesis Cyanobacteria require high amounts of Fe to convert N2 to biologically usable forms (NH4+, NO3-, NO2-) Often a limiting nutrient for phytoplankton
Major biological processes
Autotrophy = Photo/Chemosynthesis - 6H2O + 6CO2 + energy → C6H12O6 + 6O2 (energy from sun or chemicals) Heterotrophy = Respiration - C6H12O6 + 6O2 → 6H2O + 6CO2 + energy Autotrophic organisms synthesize organic matter using light or chemical energy (primary production: plants, protists, some bacteria, archaea) Heterotrophic organisms consume autotrophic production to gain energy and make more cells (secondary production: animals, fungi, some bacteria, archaea)
Beaches
Beaches form in the littoral zone: - Between the seaward boundary of land vegetation and the point where sediment is no longer distributed by waves (~ 10-20 m depth). (according to geological oceanographers!) This zone includes the coast and shore
Beaches and Human Structure CONT
Beaches naturally migrate inland as coastal storm erosion transports sand offshore - Barrier island beaches migrate due to natural processes. - Structures built to prevent those migrations. Seawalls or groins are built to restore beach sand and protect the property from wave damage. - often have unintended consequences.
Benthic fauna
Benthic/Benthos = seafloor Epifauna = Organisms that live on top of the seafloor - seaquirts, crabs Infauna = Organisms that live within seafloor sediments - hard and soft clams, tubeworms
Benthos
Benthos: Organisms that live in or on the seafloor very diverse organismal group, dominated by invertebrates Exists at all sediment depths - even on the deep seafloor Requires adaptation to unique environment - Deep benthos rely on OM raining down from upper ocean or chemosynthesis - Shallow, coastal benthos experience variable conditions Different types of sediment - Mud - organisms can burrow in - Solid rock - organisms can attach to or bore into
Beaches: The Littoral Zone- Berms
Berms - Created by storm wave erosion of sand Identified where the beach slope steepens abruptly, top of berm is usually flat and the seaward side slopes downward relatively steeply Higher berms are caused by earlier storms Highest berm is called winter berm
Asexual reproduction
Binary fission: a single-celled organism divides into two offspring Fragmentation: similar to binary fission only for multi-celled organisms Vegetative: single individual divides into many Solves the problem of having to find a mate, but offspring become genetically identical to parents, which can lead to aggression, ex = Portuguese Man O War
Formation and Modification of Coasts CONTTTTTTTTTT
Biological Processes - Uplifted and eroded coral reef forms a jagged shore often called ironshore
Seasonal Cycles in Primary Productivity
Biology, nutrients, light, water temp vary with latitude - Substantial seasonal variations occur in mid and high latitudes, but not in the tropics and subtropics - Important Caveats: --Latitudinal boundaries are not strictly defined --Characteristics are modified by local conditions/influences
Estuaries
Can be classified on the basis of their geological origin: - coastal plain, bar-built, tectonic estuaries, fjords
Coastal Oceans and Estuaries
Coastal Zone Variables - Salinity - Depth - Temperature - Waves and Tides - Turbidity and Photic Zone - Currents = dominated by local winds and tides, interact with shoreline - Nutrients Estuaries - shallower, more influence from rivers/land, tides compared to coastal ocean - the above properties differ accordingly
Special characteristics of coastal oceans CONT
Coastal ocean bathymetry and rivers: - Variable salinity, temp. (ex = Amazon River plume) - Coastal currents can be independent of ocean currents and gyres - More sources of nutrients than the open ocean - Benthic (bottom) organisms are more diverse, abundant, and commercially valuable
Polar regions
Common conditions at both Poles: - Extreme variations in light seasonally. - Low surface water temperatures - Seasonally variable ice cover - High winds promote mixing and prevent thermocline formation - High nutrient abundance (*Antarctic can be iron-limited)
Community/niche
Community = organisms that coexist in a given location - Multi-species - Multiple scales Niche = range of environmental variables where a species can survive. - competition with other organisms impacts niche use
Zooplankton
Consume phytoplankton and pass this energy to the next trophic level holoplankton - live entire lives as plankton - Species include krill, CaCO 3 shelled foraminifera and pteropods, and silica shelled radiolarians, jellyfish, ctenophores, and salps meroplankton - Zooplankton as eggs, larvae, or juveniles then benthos or nekton as adults - numerous species of crustaceans and echinoderms (such as sea urchins and cucumbers)
Coral broadcast spawning
Corals releasing eggs and sperm into the water column Precisely times on one night by the tidal cycle and moon phase
Algal Blooms can cause dead zones
Dead zones in the Gulf of Mexico, also Chesapeake Bay Dead zone size varies year to year Typically greatest in the summer after spring blooms and when water temps are warmer (gasses are less soluble)
Profiles of Nitrate (Nitrogen) and Dissolved Oxygen
Deep Pac: higher NO3, lower O2 concentrations than deep Atl "Young" water forms and sinks in high latitude N. Atlantic - has higher [O2 ] - recent contact with atmosphere, photosynthesis [O2 ] decreases with "age" and travel time - bc O2 is consumed during respiration NO3-] increases with depth, "age" - decomposers release nutrients back to the water
Deposit feeding
Deposit feeders eat food found within the sediments Often concentrated in the upper layers of sediment where there is the most food and access to oxygen They tend to ingest the sediments and digest any organic matter in that sediment, then they excrete any inorganic material that they cannot digest Protected from predators but have to go through a lot of sediment to find enough food Their food is mostly bacteria and other microbes. Deposit feeders tend to be mostly annelid worms.
Plankton (diatoms)
Diatoms have a siliceous frustule (hard external "shell"), are among the largest phytoplankton and are desirable as food for larger zooplankton and small herbivorous fishes - require Si as a nutrient to form their shells - dominant species on the coast and shelf
Mesopelagic Zones
Diurnal Migration: - Copepods, flagellates, Nautilus, and other zooplankton. - Migrate to mesopelagic by day to lessen predation pressure. - Use photophores to throw off predators. - Feed at night. - Have to adapt to changing pressures, maintain buoyancy.
Ecology
Ecology: the study of relationships between species and between species and their environment All species must: - Have adequate food supply at all life stages - Survive to reproduce successfully Ecological life history strategies are designed to maximize getting food, avoid predation, and successfully reproduce There are trade-offs inherent in nearly every life history strategy
Sargasso Sea "floating ecosystem"
Ecosystem in the N. Atlantic Ocean centered on large masses of Sargassum sp. drift algae maintained by physical oceanographic currents. Largest open drift algae ecosystem. (occurs in coastal ecosystems at smaller scale.) No upwelling or big source of nutrients, low Primary Productivity. Sargassum transported to Sargasso Sea via the Gulf Stream. Gyre currents corral Sargassum sp. to allowing it to persist. Provides food and shelter for many species of slow-growing invertebrates and fishes.
Classifying Estuaries by Circulation
Estuaries are most often classified on the basis of circulation characteristics as: - salt wedge - partially mixed - well-mixed - fjord - inverse estuaries Different segments of a single estuary can exhibit different circulation characteristics Segments may change classification based on river flow rate change (for example) (A) Salt Wedge: Freshwater runoff yields a low density surface layer that creates a stratified water Column - Can extend far offshore if freshwater flow rate is high, esp. when winds blow offshore (B) Well-mixed: At low freshwater flux and/or strong wind mixing freshwater can be completely mixed with ocean water
Estuarine Biology
Estuaries challenging places for organisms to live due to variable conditions Changes in salinity are particularly difficult since they change the osmotic pressure Fewer species live in estuaries than in the open ocean Estuaries generally have abundant nutrients and light sustain high biomass Some species of fishes migrate through the estuary as part of their lifecycle: - Anadromous fishes such as salmon live most of their lives in the ocean but return to freshwater to spawn - Catadromous fishes such as eels live most of their lives in freshwater but migrate to the oceans to spawn # of species of marine, estuarine, and freshwater origin varies within the salinity gradient of a typical estuary Species diversity is low in the brackish water section of the estuary where the salinity stress is greatest for both freshwater and marine species
Particle and Contaminant Transport in Estuaries
Estuarine circulation tends to trap particles and their associated contaminants in the estuary
Deep seafloor
Even lower food supply - suspension feeding is not advantageous. Deposit feeders relatively abundant (sea cucumbers, brittle stars). Chemosensory adaptations enable some fish to detect fallen carcasses.
Benthic suspension feeding
Ex = cockle Lives inside the sediments and sticks its siphon tubes out on the sediment into water column Water flows in one tube and out the other It's safe from predators if you live in sediments but there isn't much food there so that's why it would filter feed from the water column
Live Birth (Viviparous)
Ex = humans, whales, sharks Takes a lot of energy for mother to grow, but gives greater chance of survival
Mobility
Ex = Anemone and hermit crabs Young hermit crabs will often pick up a young sea anemone to attach to their shell and they become partners for life, they even grow at roughly the same rate When hermit crabs outgrow their shell, they often take the sea anemone with them to the new one Some sea anemones have gone so far as to cover most of the surface of the hermit crab's shell so when the crab eventually outgrows the shell, he doesn't have to move Mobility allows for a much larger forage area for the anemone, and the anemone protects the crab with stinging tentacles
Parasitism
Ex = Cymothoa exigua (tongue-biter) - Enter their hosts through the gills, beginning as males but changing sex as they grow older - At her first opportunity, a newly female exigua climbs into the host's mouth and attaches herself to the tongue, draining blood through her front claws until the tongue gradually atrophies and disappears - Hooking her spiny tail into the remaining stump, the vampiric isopod can now be manipulated by her host as a fully functional new tongue
Formation and Modification of Coasts: River-Borne Sediments
Ex = Mississippi River Delta Coasts are formed/modified as rivers deposit sediments. Most rivers flow across a gradually sloping coastal plain before reaching the sea. rivers slow down, sediments fall out in this flatter area. - forms a delta (after the valley fills in)
Mutualism
Ex = clownfish and anemone - Clownfish benefits = hide from predators, lay eggs in anemone tentacles to avoid predators so they don't need as many eggs, can eat the anemone mucus, food scraps, or the anemone tentacles, possibly the anemone tentacles sting and remove external parasites - Anemone benefits: cleared of dead tissue, mucus, food wastes, and external parasites, protection from predators by the anemonefish, freedom to remain open when the fish fights off predators means they can feed more with more time open, sometimes the anemonefish feeds the anemone
Commensalism
Ex = remora and sharks/fish - The remora that rides attached to sharks and other fishes - Remoras have evolved on the top of their heads a flat oval sucking disk structure that adheres to the bodies of their hosts. Both remoras and pilot fishes feed on the leftovers of their hosts' meals.
Pelagic suspension feeding
Ex = salps The body of a salp is basically a barrel covered in mucus Live together in a colony, which forces water to flow through the individuals in a current The current of water flow allows them to filter feed from the passing water Each individual is more likely to find food with the colony working together to move through the water column There are many predators in the water column, food is dilute in the water column, it costs energy to filter the water
Bathypelagic Zone (1000m-4000m)
Fewer prey items Brightly colored fish - unknown advantage. Use photophores to detect prey, avoid predators.
Communication CONT
Fish generate sounds from swim bladders Shrimp use claw to make snapping noise
Aphotic zones
Food Sources: - Particulate detritus raining out from above. - Sinking carcasses of large animals. - Prey from the aphotic and photic zones.
Salt Wedge Estuaries
Freshwater flows seaward over seawater flowing landward Layers separated by a strong, sharp, halocline Lower layer water mixes upward into the freshwater layer along the estuary Little or no freshwater mixes downward Halocline is inclined up to the right* (looking from ocean) due to the Coriolis deflection. (*N. hemisphere!)
Special characteristics of coastal oceans
Geophysical Characteristics: - Coastal oceans are shallow → water movements are affected by the seafloor and the coastline - Rivers discharge freshwater into coastal waters with implications for biology, chemistry, etc
Formation and Modification of Coasts CONT
Glaciers - melting over last 15,000 years, since last Ice age - glaciers cut narrow, steep valleys as they retreat creating fjord systems - fjords are characterized by submerged sills ---made of glacially deposited sediments and rock (aka moraines)
Fe as a limiting nutrient in high nutrient low chlorophyll (HNLC) Regions
HNLC = high nutrient, low chlorophyll - plenty of nitrogen, why is there not more chlorophyll?? Low primary production in HNLC regions of the ocean explained by iron limitation Iron limits net community production in up to 1/3 of the world's oceans
Succession
Herbivore and carnivore life cycles are sequenced to match phytoplankton or zooplankton food source availabilities If the phytoplankton species succession is disrupted - impacts felt by other species in the food chain
Arctic communities
High freshwater runoff, ice exclusion produce low surface salinity and a halocline. Less mixing than the Antarctic (still very high relative to other regions). Marine mammals at top of food chain (different species than Antarctic). Polar bears present in the Arctic - main predators of seals. Feeding grounds for whales (breed in tropics)
Nutrient Supply to the coastal photic zone
High nutrient (N, P) inputs from land yield the highest productivity in the ocean The most important mechanisms: - Coastal upwelling, turbulence, and river inputs Rivers and runoff supply estuaries and coastal waters Nutrients can come from natural and anthropogenic (manmade) sources Nutrient supply via coastal upwelling - nutrient rich bottom waters are upwelled to replenish depleted surface waters and fuel primary production
Rocky Intertidal Communities CONTT
High tide zone: - Extreme swings in T,S; must be protected from dehydration/desiccation - Waves become a problem. - Barnacles, limpets, and snails adapted to prolonged exposures, waves - Macroalgae (Fucus sp.) with flexible stipes and holdfasts adapted to withstand waves
Sargasso Sea biology
Home to a diverse community of fish, invertebrates (>100 sp.). At least 10 species are endemic (found nowhere else) to Sargasso Sea - including crabs, shrimp, anglerfish. Feeding grounds for tuna, marlin, swordfish, sharks. Breeding grounds for eels, marlin. Stopover site for humpack whales, nursery habitat for turtles, other species.
Geological origins of estuaries
Hudson River basin-New York Harbor-Raritan Bay - complex estuary - partial characteristics of a coastal plain estuary, a fjord, and a bar built estuary in its different segments
Beaches and Human Structure
Humans love beachfront property! (houses, condominiums, hotels, marinas, and other commercial establishments). Structures built next to the beach are vulnerable to damage by storm waves.
Beaches and Human Structure CONTT
Inlets are often protected by extending jetties out on either side of the inlet. Aids navigation, protects inlet from erosion. Sand builds up on the upstream side and is eroded from the downstream side. Sand can build up until it spills around the jetty into the inlet
Kelp Forests: Life cycle and communities
Kelp is eaten directly by only a few species (urchins, snails, few fish) when fragmented it supports many species of detrital grazers. The kelp forest canopy provides shelter and a variety of habitats for many invertebrate and fish species.
Antarctic Communities
Krill are an abundant food source for a variety of higher organisms. Mammals are abundant as top predators (or as filter- feeding baleen whales). - Fat layers are needed for insulation for cold temps, low food conditions in summer. - Krill supply food supply in summer. Fish have unique blood chemistry to adapt to cold.
Formation and Modification of Coasts
Landslides occur often on volcanic islands (e.g., Hawaii) with steep underwater flanks Relatively "Common" occurrence in volcanic island history (every 100,000 years in Hawaii). Tsunamis may result from landslides (or other events) Canary I. landslide could impact US via tsunami.
Principles of life
Life is composed of organized nonrandom structures - Molecules: Complexes→ Cells → Organs → Organisms Seawater = H 66%, O 33%, Cl 0.33%, Na 0.3% Cells = H 63%, O 26%, C 10%, N 1.4% - Maintaining this difference in composition takes energy - Synthesis of complex compounds from simple precursors takes energy
Adaptations to Wave Action
Limpets, chitons and periwinkles use their foot for suction Crabs have flattened body shape and have strong legs for gripping rocks Sea slaters are quick and live in spray zone. - Quick movements to avoid waves, predators Mussels attach via strong, byssal threads why they can use for movement as well
Rocky Intertidal communities CONTTT
Low-tide zone: - No threat of desiccation - high wave action - plentiful nutrients brought by tides - Dominated by macroalgae (Chondrus crispus), encrusting algae - Anemones, sponges, sea stars, shrimps, nudibranchs, crabs, fish, filter feeders - No mussels - eaten by sea stars
Hunting and defense
Lures Ex = deep sea anglerfish - bioluminescent lure on its head attracts prey, but possibly predators as well, in addition to high energy cost Camouflage Ex = hatchetfish - bioluminesce at the bottom of its belly makes the fish almost invisible to predators from below, but costs a lot of energy Hunting ex = sharks - ampullae of Lorenzini to sense electrical signals in the water, aid in hunting
Kelp forests
Macroalgal 'forests' that grow in cold (<20°C) nutrient rich (upwelling areas) waters seafloor is within the photic zone so new growth can photosynthesize Require stable, preferably rocky substrates upward to the surface supported by gas-filled sacs and can form a dense canopy at the surface. Kelp obtain nutrients from the water column through the surface of its fronds Very highly productive Kelp fronds can grow as much as ½ a meter a day
Navigation
Mainly hearing and chemical sensing (like sense of smell) Echolocation in cetaceans Recall that light is attenuated quickly in seawater (still some species use vision)
Coral Reefs
Many reefs are located around islands or submerged pinnacles that are sinking isostatically Isostatic sinking, sea-level rise increase water depth - decreasing the amount of light reaching the corals for photosynthesis Coral reef growth is expected to decline as the ocean becomes more acidic due to dissolution of calcium carbonate.
Beyond the Sun's Light: Mesopelagic
Mesopelagic fish species: often odd-looking, red, have unusual adaptations. Why? - Take advantage of meals of opportunity (unhingeable jaws, expanding stomachs) - Detect food sources in very low light environment, camouflage self (eyes, photophores) - Confuse prey, predators, detect mates (lures, photophores) - Red color doesn't reflect ambient light.
Seasonal Cycles
Mid-Latitude Phytoplankton Species Succession: - Typical sequence of phytoplankton species dominance during spring and summer: --Diatoms dominate until silica is depleted and are then replaced by flagellates
Rocky Intertidal Communities CONTTT
Middle tide zone: - High wave induced turbulence -- Organisms that adhere to rocks are well-suited here (mussels, barnacles, limpets) - Mussels: limited at the: --upper end by atmospheric exposure --lower end by sea star predation - snails, worms, crabs, hermit crabs, and algae live within mussel beds
Fisheries
Most of the world's production of fish biomass occurs over a small ocean area Most productive fisheries: coastal regions, upwelling zones Coastal fisheries: more productive due to ↑ nutrient inputs, ↑ food web trophic efficiency relative to open ocean Food web trophic efficiency, primary production is highest in upwelling regions
Formation and Modification of Coasts CONTTT
On an indented coastline, erosion occurs fastest at headlands Sand (formed via erosion) accumulates within the intervening bays Preferential erosion of headlands straightens the coast over time (removing the headlands) New Jersey- former headlands along the northern shore have been eroded, moving sand downshore
Feeding adaptations
Mussels, barnacles are filter feeders - allow tides to deliver food Chitons, gastropods, limpets feed using a radula (membrane with longitudinal rows of iron-containing teeth) - Scrape algae off rocks when submerged. shoreline ecosystem with rocky physical environment organisms segregated into "zones" - upper boundary -physical limitations - lower boundary -competition/predation Stressors: - variable wave energy - variable desiccation, temperature, salinity - competition, predation Adaptations: - waves: suction, speed, body shape, abyssal threads - desiccation: close opercula, fast movements
Fjord Estuaries
Narrow, much deeper than other estuaries Estuarine circulation is restricted to depths above the sill (partially mixed or salt wedge) Mixing is somewhat enhanced by turbulence at the sill Vertical mixing does not reach the bottom waters and many have hypoxic or anoxic bottom waters
Nitrogen cycle
Nitrate (NO3-)→ Nitrite(NO2-)→ Ammonium(NH4+) More complex than Phosphorus because there are more ion transformations carried out by bacteria, cyanobacteria Gas exchange at the ocean surface
Distribution of Nutrients and Dissolved Oxygen
Nutrients consumed to depletion by photosynthesizers in the photic zone - then released below the thermocline via respiration and decomposition [Dissolved O2 ] is high in surface waters, decreases below the thermocline as O2 is used in respiration and decomposition [O2 ] increases with depth below the thermocline - Deep ocean water comes from high latitude, O2-rich surface water
Organic carbon (OC)
Organic matter (OM): the nonliving remains of biological material C is the major constituent, OC is quantified as a proxy for OM Operationally-defined as particulate or dissolved Oceanic OC pools are comparable in size to atmospheric CO2, terrestrial plants ~660-700 Gt C is dissolved (versus ~20 Gt particulate OC) OM and OC fuel oceanic heterotrophic respiration released as waste materials by marine life & delivered from land very important for the global carbon cycle Particulate OC sinking is the key transport mechanism for the biological pump POC export distribution follows trends found for chlorophyll
Nekton
Organisms that live in the water column and that are able to swim actively Nekton include: - fishes - squid and other cephalopods - marine mammals - a few species of marine reptiles and birds
Food sources
Other living organisms Non-living organic particles Dissolved organic compounds - DOCs in seawater are very low concentrations, so few marine species are known to rely on DOCs for their main food source - such as bacteria and archaea
Primary production and light
PP is confined to the surface ocean, where light penetrates. The depth at which photosynthetic organisms can produce only as much organic matter as they need for respiration is called the compensation depth (P=R) Light can be limited by turbidity (absorption/reflection by particles)
Primary productivity
PP is high where nutrients are ample - upwelling, near rivers - western boundaries of the continents (eastern boundary currents) - in a latitudinal band across some of the equatorial oceans Productivity in high latitudes is seasonally high (nutrients are constantly available, light limits PP except in summer) PP is lowest in remote, nutrient-limited subtropical gyres
Suspension feeding
Pelagic Benthic Methods of suspension feeding: - Actively pump water through the filtering apparatus - Move the filtering apparatus through the water - Keep the filtering apparatus stationary and let the ocean currents move through it Some species use mucus to trap particles then ingest the mucus Small zooplankton use hair-like appendages called setae to trap very small phytoplankton Other organisms have appendages designed to capture food and transfer it to a mouth (can be considered a hunting strategy)
Habitat tradeoffs
Pelagic = costs energy to swim around, if you float around you can't decide where you want to go if food isn't abundant where you happen to float you could be in trouble Benthic Epifaunal = you are exposed to predators if you just sit on the seafloor, you don't have to spend energy swimming or staying buoyant in the water, lots of food Benthic Infaunal = protection from most predators, little food, if you go too deep the sediments run out of oxygen due to respiration from bacteria and lack of mixing with the oxygenated seawater
Plankton
Pelagic organisms that drift with the ocean currents Phytoplankton - photosynthetic autotrophs (primary producers) >99% of the food used by marine animals Zooplankton - planktonic herbivores, carnivores, or omnivores The plankton at any location and time consists of many species of phytoplankton and zooplankton
Seasonal Cycles
Polar and Subpolar regions: - Water column: well mixed year-round - Frequent storms, low light intensity, no thermocline - Nutrients are plentiful - Can be modified by freshwater inputs Tropical regions: - Relatively uniform, high light intensity year-round - Nutrients limit PP which is low (except upwelling regions) - Little seasonality of phytoplankton growth - Permanent thermocline below shallow mixed layer - Deep photic zone Mid Latitudes: - PP is light-limited in winter - A spring bloom occurs in spring until nutrients are depleted - Weaker fall bloom = as cooling, storms mix nutrients back to the photic zone - Distinct seasonal cycle = well-mixed water column in winter; shallow thermocline in summer
Phosphorus Cycle
Phosphate (PO^3-4) recycled efficiently by the microbial loop Not usually limiting
Water column
Photosynthetic organisms (photic zone) - ex = cyanobacteria, diatoms, dinoflagellates, coccolithophores, green algae Pelagic species Larvae
Rocky Intertidal Ecosystem
Physical limitations determine upper boundaries of species range Competition/predation determine lower boundaries of species range - Supralittoral Zone: Always out of water; in splash zone - High Tide Zone: Submerged at high tide - Middle Tide Zone: Exposed at low tide; otherwise submerged - Low Tide Zone: Always submerged
Food webs
Phytoplankton (1st level) are consumed by grazing zooplankton (2nd level), which are consumed in turn by carnivorous zooplankton (3rd level), which are consumed by small fish (4th level), and so on... These are food chains Each level is a trophic level Many organisms feed at more than one trophic level feeding relationships in the oceans thus form complex food webs or trophic webs Trophic Efficiency: Eating tuna versus eating sardines (assuming 10% trophic efficiency at each trophic level) Eating sardines makes use of ocean primary production 1000 times more efficiently than eating tuna
Primary production and nutrients
Primary producers require nutrients: N, P, and Fe as well as other micronutrients (Si, Zn, Co) that diffuse across cell membrane - Insufficient nutrient concentrations can limit phytoplankton growth Sources: atmospheric deposition, OM remineralization, diffusion from sediments, continental runoff (natural and anthropogenic) Small size of phytoplankton maximizes their surface area to volume - limits sinking, keeps them in the photic zone, maximizes surface area for nutrient uptake When organismal remains sink below the thermocline, this removes C, nutrients from the upper mixed layer of the oceans (and out of contact with the atmosphere) Biological pump is the removal of atmospheric carbon dioxide with storage in the deep ocean, essentially removing it for centuries microbial loop: process by which microbe decomposers recycle nutrients and organic matter in the euphotic and aphotic zones - recycles nutrients for phytoplankton, converts organic matter to CO2 - resists the biological pump P is recycled efficiently, N is recycled more slowly Si, Fe are recycled more slowly, transported to depth
Secondary Production and Decomposers
Primary production: synthesis of organic matter (OM) from inorganic compounds Secondary production: consumption of OM by heterotrophs and conversion of OM into biomass Only ~10% of OM is converted to biomass at each step in a food chain Microbial loop: Decomposers convert the waste products and/or dead tissues of organisms back to inorganic compounds via bacterial respiration
Production, consumption, and decomposition
Primary production: synthesis of organic matter (OM) from inorganic compounds. Photosynthesis - carried out by phytoplankton and cyanobacteria Photosynthetic requirements: - 1) carbon dioxide, 2) water, 3) nutrients, and 4) energy (sunlight) Primary Production can be light-, nutrient-, C-limited (rarely C limited) Chemosynthesis - phytoplankton, bacteria, and cyanobacteria - typically occurs in extreme environments (deep ocean, anoxic waters, no light) Energy to synthesize organic matter is obtained from: - oxidation of hydrogen sulfide to sulfate - transformation of metals (Mn, Fe) from a reduced to an oxidized form - oxidation of hydrogen to water - oxidation of methane to carbon dioxide and water
Microbes
Prochlorococcus: The smallest (0.5- 0.8 µm) known photosynthetic organism, a cyanobacteria may be the most abundant species on Earth - ~1027 individuals - as many as 100,000 per mL of water Prevalent in HNLC and other nutrient-limited parts of ocean Marine microbes, including Prochlorococcus, adapt to environmental conditions by acquiring and exchanging genes via viruses ~1029 bacteria in the ocean (compare that to ~1021 stars in the universe) ~billion species of microbes live in the world's oceans. ~38,000 species L-1 seawater Microbial species are everywhere - including extreme high temperature (up to about 250 oC) and deep in the ocean crust (1,400 m below the seabed) Microbial species are responsible for all the decomposition in the oceans control many aspects of ocean chemistry including, for example the nitrogen cycle in the oceans
Protist or plant?
Protista: mostly single-celled, typically 0.01-0.5 mm in size (larger than prokaryotes) - Diatoms, dinoflagellates, foraminifera, seaweeds, algae - Brown, red algae can be multicellular - Macroalgae can be much bigger than 0.5 mm Plantae: Sea grasses, mangroves, salt marsh grasses - Not algae, seaweeds!
Sargasso Sea CONT
Recognized as essential fish habitat by USA, ICCAT Important ecosystem for conservation and economics Threats: - Pollution: Same currents that corral Sargassum also corral plastics and other debris. - Overfishing. - Shipping.
Biological Processes - Coral Reefs
Reef-building corals must be underwater Reefs protect coastlines by absorbing energy from ocean waves Issues threatening coral reefs : warming waters, eutrophication, and ocean acidification
Formation and Modification of Coasts CONTTTTT
Sea caves in headlands can continue to be eroded until they meet, resulting in the formation of a sea arch As the headland erodes further the arches collapse and the remaining pinnacles of rocks are called stacks (which also eventually erode away)
Special characteristics of coastal oceans CONTT
Salinity distributions in coastal-ocean water columns: - High river discharge - Low river discharge, well-mixed water column - Strong evap, low rainfall, low river discharge, mixed water column - Strong evap, low rainfall, low river discharge, stratified water column (ex = Mediterranean sea)
Beaches and Human Structure: Habors
Santa Barbara Harbor, created by building a dog leg jetty sand accumulated on the upstream side, moved around the jetty into the harbor, forming a sand spit Harbor must now be dredged periodically.
Beaches: The Littoral Zone: Scarps
Scarps are steep slopes or miniature cliff formed by normal wave action. (analogous to berms) Located on beach where wave normally reach during high tides If two scarps are present the highest one was formed when the tidal range was larger (spring tides)
Kelp, Sea otter, and sea urchins
Sea urchins eat kelp sea otters eat urchins humans, killer whales, sea lions kill otters. Low otter abundance→ urchin populations expand, reduce kelp. Otters recover→ urchin populations decline, and kelp forests are slowly returning.
Sexual Reproduction
Separate-sexes - Sperm and egg combine: --Direct sperm transfer --Sperm/egg released into water column It increases genetic diversity which allows species to better adapt and survive environmental changes Direct transfer requires fewer sperm and eggs to be successful, so it saves energy in producing fewer eggs and sperm; however, males and females have to find each other which can cost energy in searching (some species get together at the same time and place each year to avoid this) Hermaphroditism: one organism is both sexes - Sequential: change one sex after the other - Simultaneous: at the same time - It solves the problem of having to find a mate
Reproductive strategies
Sexual reproduction: separate sexes, combine sperm and egg to form fertilized egg Asexual reproduction: do not have separate sexes Egg laying (Oviparous) Live birth (Viviparous)
Formation and Modification of Coasts: Tectonic Processes
Slow (>10^6 year time scales), but constant, modify coasts at boundaries and hot spots. Volcanic eruptions in magmatic arcs at convergent plate boundaries, can create island chains (Hawai'i) Coastline can be created or destroyed by earthquakes, that raise/lower sections of the land and seafloor. Divergent continental margins can create seas/oceans.
Plankton (Coccolithophores)
Smaller, less abundant than diatoms or dinoflagellates more abundant in ocean than coastally have a mosaic of calcareous plates covering the cell wall (need Ca2+ and CO3^2-) think about coccoliths in terms of ocean acidification
Rocky Intertidal Communities CONT
Supralittoral ("splash") zone: - Essentially on land - Spray delivers moisture, nutrients which support lichens, and blue-green algae --Grazed by snails, limpets and isopods that are adapted to long periods of dry conditions
Surface grazing
Surface grazers crawl along the bottom of the seafloor in search of abundant food Grazing can refer to eating plants or animals in the marine use of the word Some species have scraping teeth Not all species actually live on top of the seafloor, but some live in the sediments and extend up a siphon tube to "vacuum" up the seafloor surface Exposed to predators, but there is a lot of food Move slowly or are completely immobile, but reproduce quickly
Phytoplankton
Species are not evenly distributed throughout the oceans Different species dominate based on nutrient requirements and availability - Coccoliths are most abundant offshore because their nutrient requirements are not as high as Diatoms and Dinoflagellates
Rocky Intertidal Communities
Species have their upper limit defined by physical environmental stressors, lower limit by competition/predation - Variable water exposure (desiccation) - Variable oxygen concentrations and pH - Temperature swings - Variable salinity - Wave energy
Mid-Latitudes- Spring Phytoplankton Bloom Dynamics
Spring: High river discharge initiates phyto bloom Zooplankton production rises rapidly in response Bloom continues until nutrients deplete Phytoplankton biomass does not rise during bloom (consumed by zooplankton) Production (rate) = amount of carbon produced over time Biomass (concentration) = cells per volume of water
Sargasso Sea
Stressors (in absence of Sargassum): - low nutrient, low productivity waters - lack of structure for habitat/protection from predators In Sargassum: - food source - unique habitat offering protection from larger fish predators Adaptations: - efficient recycling of nutrients, resources - camouflage coloration patterns - unique life histories (e.g., the American eel) - long-lived, slow-growing species occupy Sargassum
Beyond the Sun's Light (Aphotic Zone) (Mesopelagic, Bathypelagic, Abyssal Zones)
Stressors /conditions (gradient in severity with depth): - Minimal (mesopelagic) to no light. - Low and uncertain food supply. - Uniformly low temperatures. - Increased pressure. - Detritus is major food source and decreases with depth.
Polar Ecosystems
Stressors: - seasonally low light and low temperature - climate warming and habitat loss Adaptations: - migrations - fat stores, fur coats
Feeding strategies
Suspension feeding = filter water Surface grazing = eat what's on top of the seafloor surface Deposit feeding = eat what's within the sediments
Associations
Symbiosis: when two different species live together and interact with one another - Parasitism: one species benefits, the other species is disadvantaged - Mutualism: both species benefit - Commensalism: one species benefits, the other species doesn't benefit but doesn't suffer disadvantage - Mobilization = one species can move, one can't
How do we describe life?
Taxonomy: All living things are arranged into formal groups according to their anatomy, physiology, and genetic differences "tree of life," all species are classified into 1 of 3 domains: - Bacteria - Archaea - Eukarya (kingdom protista, fungi, plantae, animalia)
Special Characteristics of Coastal Oceans CONTTT
Temperature vs depth in the coastal ocean: - shallow halo and thermoclines relative to the open ocean due to higher mixing - Polar = no stratification - Temperate = seasonal stratification (driven by temp and/or freshwater) - Tropical = no seasons, little stratification
Phytoplankton (Primary Producers)
The most abundant types of phytoplankton: - Diatoms - Dinoflagellates - Coccolithophores - Other types include silicoflagellates (silica shells), and cyanobacteria Primary production: synthesis of organic matter (OM) from inorganic compounds.
Formation and Modification of Coasts CONTTTTTT
Tide Range - Tidal currents themselves are not major agents of erosion but are factors in the severity of observed impacts. - Tidal range determines the height range over which wave erosion occurs- and the width of the shore - Large tidal range spreads wave energy over a large vertical range (less erosion) - Coasts with small tidal range erode faster because of concentrated wave energy
Formation and Modification of Coasts CONTTTTTTT
Tides and Waves - Wave erosion (combined with boring and dissolution by marine organisms) undercut this rocky coastline on the islands of Palau in the Pacific Ocean. - Erosion is confined to a very narrow height range because the tidal range is nearly zero
Formation and Modification of Coasts CONTTTTTTTTT
Tree roots (on land) and animal activities such as burrowing, can also contribute to continuous erosion of rocks and soils
Wetlands
Tremendous ecological value ("ecosystem services"): - Supply organic matter, protection from predators - Attractive places for marine animals to feed. - Habitat for juvenile marine organisms which then migrate to the sea at maturity. - Often conflict with human interests and waterfront property! Important feeding area for waterfowl trap sediments/preserve coastlines. filter nutrients which reduces eutrophication in estuaries Provide gorgeous vistas sequester 'blue' carbon
Special Characteristics of Coastal Oceans CONTTTT
Turbidity = measure of suspended solids in a liquid, obscures light penetration Turbidity = caused by particles (suspended sediments, phytoplankton, and other organic materials) - Limits light penetration, photosynthesis - ex = San Pablo Bay, more turbid, Central Bay, less turbid (estuaries)
Nutrient Supply to the coastal photic zone CONTT
Turbulence: - Turbulence mixes nutrient-rich water up into the photic zone - Long residence time of water (2-3 months) on Georges Bank very high productivity
Biological Provinces and Zones
Two provinces/ distinctly different habitats in the ocean: - Benthic (sediments) - Pelagic (water column) Each of these are separated into zones based on depth Each zone is somewhat distinct from the others with respect to environmental conditions: - availability of light - water temperature - sediment type
Migration
Typically between feeding grounds and spawning grounds (may cost a lot of energy to keep moving around) Consider different life stages benefit from different habitats Ex: zooplankton vertical diel migration, atlantic eel and salmon make migrations to reproduce (costs energy to migrate, but more food, less predators = higher chance of survival)
Formation and Modification of Coasts CONTTTT
Waves - Rock erodes at different rates - As waves cut into coastal cliffs and headlands, they preferentially erode soft, less resistant rocks. - On rocky coasts, waves cut away rock between the high and low tide lines - land becomes unstable and breaks away, leaving cliffs - Harder rocks persist and sea caves form at the base of cliffs
Formation and Modification of Coasts CONTTTTTTTT
Vegetation - The type and extent of vegetation on the coast affects the rate at which winds, streams, and storm waves erode the land. - Grasses are important in protecting sand dunes from erosion - Rooted plants (sea grasses, salt marsh plants, mangroves) that grow in the water help prevent erosion by waves and currents - plants dissipate wave energy that would
Partially mixed estuaries
Vertical mixing is greater in partially mixed estuaries than in salt wedge estuaries Halocline is weaker Partially mixed estuaries have strong tidal currents Water has higher salinity on right side* due to the Coriolis deflection. (*N. hemisphere!)
Well mixed estuaries
Vertical mixing is intense, very strong tidal currents No halocline Salinity ↑ progressively with distance down the estuary Water has higher salinity on right side* due to Coriolis deflection. (*N. hemisphere) There is a net residual current (current left after tidal motions are averaged out) across the estuary
Habitats
Water column = pelagic On top of the seafloor surface = benthic epifaunal Within the seafloor sediments = benthic infaunal
Formation and Modification of Coasts CONTT
Waves - Breaking waves are the principal coast-modifying process. - On rocky coasts, breaking waves progressively erode the rock away. - Soft, sedimentary rocks erode much faster than hard, volcanic rocks. - Erosion is faster on coasts that are exposed to high wave action. ---**Exacerbated by wind, weather events.
Nutrient Supply to the coastal photic zone CONT
West Africa coast and California coast, are both on west coasts, with eastern boundary currents (flowing toward the equator)
Beaches CONTT
Wind and weather - sand dunes are created when onshore winds carry sand from beaches and deposit it on the backshore above the highest point reached by waves - Stabilized by vegetation Sand dunes provide essential protection from waves and storm surge Sand dunes provide essential protection from waves and storm surge
Desiccation
barnacles, mussels close opercula protecting respiratory organs, trapping small amounts of water inside Mobile animals will move with water or hide in wet rock crevices until tide returns. Urchins, sea anemones, sponges restricted to low tide zone (live elsewhere).
Seawalls
built parallel to shore using large boulders, concrete, or steel, to break up or reflect storm waves. replaces (or covers) beach sand that normally would be eroded, protects the coast for some years the beach in front of the wall often disappears as sea level rises and the unprotected coast on either side of the wall retreats.
Coasts have variable characteristics
can be narrow or extend inland for long distances - e.g., rocky shorelines, mountainous coasts, sandy beaches Coastal characteristics typically extend for 1,000's of km Dynamic over time: changing on days to millennial time scales
Ecosystems
components of the Earth system that are linked by their similar physical, chemical, geological, and biological characteristics Marine Ecosystems: - Kelp forests - Rocky intertidal communities - Sargasso Sea - Polar regions - Deep, dark ocean waters below - the pycnocline - Hydrothermal vents - Coral reefs - Salt marshes - Seagrass Beds - Estuarine - Mangroves
Deltas
delta features vary depending on relative influence of rivers, tides, and waves Wave-dominated - narrow river, arcuate shoreline subject to longshore drift (Nile R.) Tide-dominated - small deltas with characteristic sand bars parallel to river flow (see below) river dominated - "birdsfoot" delta, extends out into the estuary due to river flow and sediment deposition filling in the sediments faster than they can be removed. (Mississippi R.)
River Deltas
delta soils - rich in nutrients, organics great for agriculture easily flooded and subject to drastic modifications to river courses - not great for human civilization levees control flooding but reduce soil quality
Kelp forests CONT
detrital-based food web (decomposers feed on kelp fragments) diverse community: invertebrates, fishes, marine mammals trophic cascade: kelp-urchins-sea otters-seals-whales Stressors: predation by seals, sea lions, shark, killer whales - rocky seafloor, cold waters (<20ºC) adaptations: kelp have holdfasts to grip rocks - kelp have air sacs to float up to surface waters
Marine ecosystems
ecosystem community composition depends on organisms' ability to fill niches defined by the ecosystem pay attention to stressors and adaptations that enable organisms to fill niches in various ecosystems.
Tidal Wetlands
grow on shores protected from wave action. rely on soil/sediment accumulation to provide physical environment flat, muddy or vegetated areas covered by water during only part of the tidal cycle. characterized by emergent plants: - marsh grasses in salt marshes - mangroves in mangrove swamp
Beaches CONT
offshore - seaward of the breaker zone near-shore - below the low tide line in the breaker zone (may contain longshore bars) foreshore - between high and low tide lines Backshore - area between high tide line and point reached by highest storm wave (often cliffs, sand dunes)
Estuaries
partially enclosed body of water where freshwater from rivers mix with oceanic salt water
Secondary Production and Decomposers (Bacteria and Archaea (and viruses, fungi)
planktonic, extremely abundant throughout the ocean decompose OM back to dissolved inorganic compounds (microbial loop) *Certain bacteria and archaea are primary producers and responsible for the majority of primary production, especially in tropical and subtropical oceans* Microbial loop is very important source for inorganic nutrients in the open ocean where continental sources do not exist
Susceptibility to climate change
positive feedback between ice melt and solar energy absorbance exacerbates climate change in cold regions. substantial reduction in permanent sea ice area since 1979. Sea ice is important habitat for ice algae primary producers, polar bears, penguins, seals. - Impacts on feeding and breeding grounds are expected to be profound.
Timescales of Coastal Modifications
rapid (short timescales: storms, earthquakes, landslides, tsunamis; slow (long timescales: wave erosion, river sediment delivery, sea level rise) Many processes occur on the same coasts at the same time but at different rates
Niue Sea Caves
small island in the South Pacific, world's largest coral island (coral atoll)
Plankton (dinoflagellates)
smaller than diatoms, weakly motile, not always autotrophs many have a readily decomposed cellulose cell wall but none have hard parts they tend to dominate the phytoplankton when silica concentration is too low for diatom growth more abundant in open ocean than coast or shelf
Coastal Oceans
the region between the land and the open ocean that is dominated by processes resulting from land-ocean boundary interactions includes the continental shelf, part of slope
Longshore Transport
waves approach shorelines at oblique angles net transport of sediments is in the direction to which waves are angled (to the right in the picture below) - this is longshore transport The result is that exposed coastlines/beaches are naturally altered - not great for human use!
