Marine Flashcards
What are the different parts of the ocean?
Litoral zone: the area that generally gets uncovered on a daily basis (when tides go out).
Neritic = near shore waters; oceanic = waters in ocean.
Pelagic: the whole water region (neritic + oceanic)
There are subtidal regions and then continental slope, then deeper regions.
Anything that chooses to live at the bottom = Benthic.
Planktonic: free-swimming in oceans; Benthic on the bottom (Attached or free living)
Photic: the photic zone is often measured to find out the level of light penetration; it varies in depth dep on location, could be deeper, ~1% light level 200m down.
why is water an excellent solvent?
It dissolves more substances and in greater quantities than any other common liquid: salts, sugars, acids, alkalis, and some gases including oxygen and carbon dioxide
Cell components such as polysaccharides, proteins and DNA are dissolved in water and derive their structure and activity from interactions with water
What are the key nutrients that cause the most problems in the ocean?
These key nutrients arrive through river run off (sometimes nitrogen from rain + snow)
- Hydrothermal vents might also add sulfide + chlorides
- These all contribute to salinity of oceans + you can use a refractometer to measure salinity of our oceans.
how many ions make uo 99% of the ocean?
Six ions make up ~99% of the salts dissolved the ocean with Na and Cl making up 85%
why is borate important?
without low concs, a lot of things can’t survive - this is in trace concentrations.
how is a Rosette of submersible water samplers with probes used to measure the salinity / other things about the ocean?
There are collumns you can detach from the core, and when you send a messenger, it will trigger one of them to close. This means that at a certain depth you will trap water at intervals by operating a different column each time í depth profile of the oceans. You can also get temperature info etc.
how are oxygen minimum zones replenished?
by ocean circulation
Oxygen circulation solves most problems with oxygen minimum zone
how can light penetration in oceans be measured?
- Secchi disc( - simple, painted areas of black / white, put on cable + lower it into water column until disappears, used a lot in FW) , or submersible ‘photocells’ or quantum metres - needed in oceans: they measure wavelengths of light / or just measure at the top + lower at intervals + get the attenuation of light in the water column.
- Photocells with colour filters allow you to work out wavelengths: in oceans blue light penetrates deeper than red. UV attenuated quickly, at low levels dissolved organic carbon will stop it going which is good because this is dangerous
- In FW more green light.
What are the different light levels in the ocean? how is light penetration different in oceanic + coastal waters?
euphotic or photic is zone where there is enough light for photosynthesis (more or less down to 1% of surface light).
- Disphotic or dysphotic zone has enough light for organisms to see and aphotic does not.
- Water penetrates much further in clear oceanic than in turbid coastal waters : in clearest oceanic waters, penetrates to over 1000m in sunlight, but in coastal waters only to 200m.
why are salinity ocean profiles variable?
due to rainfall, evaporation and river run off
why do seasonal thermoclines arise and why are they bad?
- Surface layer (warm); intermediate layer (permanent thermocline) + Deep layer (very cold but generally a constant temperature)
- Temperature and density are mirror images of each other
- In temperate and polar waters a ‘seasonal thermocline’ may develop: during the summer there can be another thermocline that happens much higher up - temporary thermocline causes layering of water in the upper layer - pink region. - when you get a T gradient, hard to break it down (water lower down doesn’t mix), orgs trapped in layers can run out of nutrients because of this lack of nutrients)
What is the Coriolis effect?
Currents + winds are:
- Deflected to the right in the northern hemisphere
- Deflected to the left in S. hemisphere
Why does the polar zone only have a late spring boom?
dark much of the year until late spring: - only a narrow opportunity.
What makes regions of coastal upwelling good fishing grounds?
- Prevailing wind blows parallel along coast + Ekman transport carries surface water away from shore at 90 degree angle
- Deep, nutrient-rich water is upwelled to fill the gap, making it very productive
- This fuels the fisheries + birds.
How do organisms cope with wave action?
o Mobile organisms can shelter from wave action (or ‘clamp down’)
o Low profile
o Sessile organisms can adapt to withstand wave action
o Giant green sea anemone (Anthopleura xanthogrammica)
o Compact shape reduces area exposed to wave action and water moves easily over them
Adaptations to wave action in kelp (brown seaweeds) - how?
o Flexible stipe
o Streamlined shape
o Strong holdfast
o Might lose photosynthetic blades but meristem helps them regenerate
Coping with wave action - Going it alone or in groups(mussels)? (advantage vs disadvantage)
- Large single exposed mussles tron away
- Clusters reduce exposure, water flows over
- Too large cluster, too much strain on those attached to the rock –> torn away
Subtle balance to survive on the rocky shore
Name challenges of Variable periods of immersion and emersion
o Variable periods of desiccation + of time in light
o Exposure to UV and exposure to salinity gradients (rain)
o Wind activity (important for desiccation
o Lack of food ~12h without water if at the top (~3h in the middle, ~30min at the bottom) í shot window of opportunity
When are the largest tide-greatest tidal amplitudes?
New moon and full moon
Spring tides = greatest gravitational pull (march and September have the strongest tides)
Every day tide advances ~1h: differences in exposure every day
Define Supralittoral/Littoral fringe/Splash zone, Intertidal/Eulittoral zone/Midlittoral and Sublittoral
The supralittoral zone, also known as the splash zone, spray zone or the supratidal zone, is the area above the spring high tide line, on coastlines and estuaries, that is regularly splashed, but not submerged by ocean water. Seawater penetrates these elevated areas only during storms with high tides.
The intertidal zone, also known as the foreshore and seashore and sometimes referred to as the littoral zone, is the area that is above water at low tide and under water at high tide (in other words, the area between tide marks).
The sublittoral is the environment beyond the low-tide mark and is often used to refer to substrata of the continental shelf, which reaches depths of between 150 and 300 metres.
How do Littorina cincta (periwinkle) protect themselves at low tide?
o Periwinkle: Move to moist crevice, clamp to rock and seal shell with operculum (part of exoskeleton that will close over hole to avoid desiccation)
What are Zonation Patterns?
o Typical vertical zonation patterns
o Tend to follow a predictable pattern
o Different zones dominated by different organisms
o The pattern may shift due to turbidity, degree of exposure, pollution, temperature, etc.
What happens after an oil spill?
o Surfactant killed organisms, recolonization was observed
o Pioneers that could capitalise on bare surfaces took over: Enteromorpha (green seaweed) (renamed as Ulva now)
o Animals come back later (limpets, Patella spp.); start grazing on the weeds and biomass overall goes down
o Ca. 10 years to recover from oil spill estimated
Removal experiments: what happens when you remove starfish?
Starfish as a structuring force (predation): they are voracious predators.
o Spring 1963 to summer 1968 manually removed sea stars (Po) in Mukkaw Bay o Mussels (Mc) colonise further down shore, replacing barnacles (Pp)
Starfish maintain the diversity of the mid-intertidal region (see text book pp. 258). Without sea stars to eat the mussels, the mussels outcompete everything and dominate the shore (=keystone species).
Explain the Intermediate Disturbance Hypothesis
The intermediate disturbance hypothesis (IDH) suggests that local species diversity is maximized when ecological disturbance is neither too rare nor too frequent. At high levels of disturbance, due to frequent forest fires or human impacts like deforestation, all species are at risk of going extinct.
o Initially it was thought that there were ‘predictable’ zones on the rocky shore
o But zones are not fixed in position and species can migrate up and down
o When a clear patch occurs, patterns of recolonization and regrowth (or succession) can be difficult to predict
o What regrows may depend on what reaches the space, the time of year, size of space, etc.
What are some biological differences between Antartica and the Artic?
6x the species found in the Antarctica.
Very high biomass in the Antarctic: indication that it must be much harsher in the Arctic.
In antartica: • High diversity of soft and hard benthic habitats –> High diversity of epifaunal and infaunal benthos - because there is Different substrates enabling different sorts of attachment/nutrients/gradients of gases
Biotic disturbance high in the Artic (bioturbation of sediment (sandy sediment very easy to disturb)
What are the different types of feeding of benthic organisms?
Filter feeding: suspension feeding in which water is actively pumped or filtering structures are swept through the water
Passive suspension feeding: no active pumping of water but use of cilia + mucus to move particles to mouth.
Deposit feeding: feeding on particulate organic matter that settles on the botom
Biological differences – the Arctic
What are some physical differences between Antarctica + the artic?
Narrow shelf and exchanges with the deep ocean in the Antarctic; Less connectivity in the Arctic.
Big difference in the river output (there is none in the Antarctic). Can be negative but also nutrients: less stable salinity in the Arctic, changes as river water comes in.
Cooling at the poles (water has greater density), but in Antarctica, clear run all around (circular). In arctic, limited strait and transpolar currents.
Euphoric zone nutrients: in Antarctic, no limitation in primary productivity during summer (experienced in temperate regions).
High seasonality in pack ice in Antarctic, cover and thickness of ice vs little seasonality in the Arctic.
What are the two straits in our oceans?
The Fram Strait is the passage between Greenland and Svalbard
The Bering Strait is a strait of the Pacific, which borders with the Arctic to north. It is located between Russia and the United States.
What may climate change lead to in terms of our oceans + the movement of organisms?
huge impact of climate change here because there all the ice free conditions in the Canadian artic that lead to connectivity between oceans impact on primary producers.
What are some features of the Southern Ocean?
- Deep water and pelagic marine ecosystems open to Pacific, Indian and Atlantic Oceans.
- Species reliant on the continental shelf are isolated.
- Two circumpolar surface currents.
- Deep or open water species are well distributed
- Creates a convergence zone = upwelling of nutrient rich deep water.
why can there be high summer productivity in the southern ocean?
- Phytoplankton blooms occur along convergence zone (upwelling of nutrient rich deep water) and ice margins.
- Biomass at any given depth in Southern Ocean are 10x to 100x that of the same depth in the Arctic Ocean.
Where are the coldest waters on Earth?
• Antarctic continental shelf waters coldest anywhere on Earth = 0 to -1.9°C
What are some differences in ice cover between the artic + Antartica?
Arctic
• Arctic pack ice is more persistent, harder and thicker than Antarctic.
• Central Arctic permanent ice cover.
• Average age 10 years.
Antarctic
• Antarctic pack ice cover more seasonal.
• During winter cover ~19 million km2 of ocean = 2x USA.
• Dramatic year-year variations in pack ice extent (significant changes: due to climate change?)
what are the different types of ice?
- Sea ice (pack ice): Formed from saltwater - freezing onto base of pack ice
- Icebergs are chunks of ice shelves or glaciers that calve into the ocean
- Ice shelf (continental ice sheet or glacier – i.e. formed on land – extends onto the sea.) Formed from snow = freshwater
why is sea ice a rich feeding ground?
High species richness in the zooplankton communities: are waiting for ice to melt to release organisms such as diatoms.
Sea ice and primary productivity
• As sea ice melts in Spring it provides a “seed” population for plankton blooms along the ice edge.
What make the southern Ocean food current possible?
- Simple, short & efficient.
- Primary producers & Primary Consumers, then whales
- Based predominantly on a single zooplankton species, Antarctic Krill
- Dependant to organisms like diatoms
- Circumpolar current and upwelling make this possile
What happens in the oceans in the absence of krill?
salps can exploit spring phytoplankton bloom and undergo explosive population growth.
• High densities in years following low ice cover.
• Tolerate warmer water than krill.
What are ice sours and how are they produced?
Caused by icebergs or hard pack ice, physical force that will strip off everything on the bottom. Seabed gouging by ice is a process that occurs when floating ice features (typically icebergs and sea ice ridges) drift into shallower areas and their keel comes into contact with the seabed. As they keep drifting, they produce long, narrow furrows most often called gouges, or scours.
What are the effects of ice sours on a regional + local scale?
• Local scale:
o high faunal mortality
o skewed population structures
o dominance by mobile secondary consumers (e.g. echinoderms, crustaceans).
• Regional scale:
o promotes biodiversity & habitat heterogeneity
What is the relationship between Polynyas and penguins? Why is this so?
90% of Adélie and Emperor penguin colonies are sited next to recurrent coastal polynyas. Ep breeds on fast ice cover.
Polynyas: ‘sea ice factories’ = an area of open water surrounded by sea ice. Able to receive benefit for all of the upwelling water (far more productive) and represents important feeding area. Can be produced by katabatic winds
Define Estuaries
Estuaries - semi-enclosed areas where rivers meet the sea (Chesapeake Bay, Delaware River, Cape Hatteras)
Many types of estuary; Drowned river valley estuaries; Bar-built estuary
What is a Fjord?
Fjord - a long, narrow, deep inlet of the sea between high cliffs, as in Norway, typically formed by submergence of a glaciated valley.
Much clearer and much deeper, less turbidity than estuaries (Milford Sound, New Zealand)
What are the 6 Physical Characteristics of Estuaries?
1) Salinity (v variable)
2) Tides (tidal inundation)
3) Oxygen (concentration v variable bc of organic matter in estuaries)
4) Nutrients
5) Sediments
6) Turbidity(much harder to live in water column)
How does the salinity in estuaries vary, why is that and what effect does that have?
Salinity: typical salt-wedge type estuary;
–> Saltwater is denser than the freshwater (river) and flows along the bottom
o Salinity is highly variable; the salt wedge can move up & down the estuary with the tides
o Also, daily and seasonal variations in tides and river flows
o Huge amount of osmotic stress on organisms
o Actual volume of water coming from the river very variable
What is the sediment in estuaries made out of and what is the Estuarine Turbidity Maximum?
Sediment =Large amounts of organic (& non-organic) particles associated with the tide and river flow. Organic matter will flocculates.
Estuarine Turbidity Maximum - organic matter flocculates where it meets the salt wedge (form part of the sediment).
o Maximum aggregation of particles where seawater and freshwater meet
o Settles to form a nutrient rich mud, but turbidity reduces light penetration reducing photosynthesis
What are the 4 types of organisms with different salinity tolerances called?
o Stenohaline - narrow tolerance to salinity changes (marine species; 30 parts/1000)
o Euryhaline - broad tolerance to a range of salinities
o Truly estuarine =blackish water species (brackish water = intermediate salinity and contains stenohaline & euryhaline organisms)
o Freshwater species
–> Organisms can move and avoid, or seal themselves away, from extremes of salinity. But euryhaline organisms need a physiological response.
What is a Perfect osmoconformer and a
Perfect osmoregulator ?
Perfect osmoconformer - salinity of blood matches that of water (salmon).
Perfect osmoregulator - salinity of blood (ionic concentration) stays constant even though external salt concentrations varies (crab).
Define mudflats and what properties do they have?
Mudflats: deposits of sediment in sheltered intertidal areas (like estuaries)
–> Salinity changes are less dynamic in interstitial water, more stable environment within the mud.
–> Plentiful nutrients and though biodiversity may be low, primary production may be very high…
o Sediments can be anoxic (only top few cm oxygenated, with anaerobic bacteria living underneath)
o Hydrogen sulphide accumulates in mud and can be toxic
o Anaerobic bacteria can thrive
What are the Primary producers in estuaries?
o Phytoplankton (e.g. dinoflagellates, bc they have flagella, they can ride the salinity layers and capitalise on that í don't need to tolerate big osmotic fluxes) o Macroalgae (seaweed) o Macrophytes (seagrass) o Benthic biofilms (microphytobenthos) o Saltmarsh plants (halophytes)
On the energy budgets in estuaries What are the 2 Carbon supply extremes?
Carbon supply can be (2 extremes)
o Allochthonous: depend on external sources e.g. Dollard (in the Netherlands, 46% coming from North Sea and River Ems, too dark for phytoplankton so less production)
o Autochthonous: fixed by primary producers within estuary e.g. Barataria estuary (39.6% of carbon input from saltmarshes at edge of estuary –> American estuary: greater intertidal properties)
Define infauna in estuaries
Infauna: benthic organisms that live within the bottom substratum of a body of water (i.e. capitalise on the mud)
o Snails (live in burrows, capitalising on the organic water falling down in the water column: scavenging) o Polychaete worms o Clams o Crustaceans
What are the temporary visitors in estuaries?
Atlantic medhaden (Brevoortia tyrannus) uses the estuary as a nursery but breeds at sea as do many other fish and shrimps. Blue crab (Callinectes sapidus) females can undergo long migrations to spawn at sea, before their young move into the estuarine environment
