Marine Science Final

soft bottom vs. hard bottom

soft:
- less macroalgae and macroherbivors
- more deposit feeders
hard:
- more macroalgae and macroherbivores
- less deposit feeders
- more competition

beach wrack

algae and seagrass washed up on beach, used as food source and habitat

sources of sand

volcanoes, eroded coral reef, rocks and minerals

characteristics of intertidal fish (5)

small, cryptic coloration, tolerate range of temps (eurthermal) and sallinity (euryhaline), some can breathe air

stresses in the intertidal (4)

• air exposure

• desiiccation

• temperature stress

• wave shock stress

dessication and adaptations

stress of losing water, drying out
- shelter in crevices
- trap water externally or internally
- remain inactive when exposed to air

wave shock stress adaptations

• small size, low profile

• flexible (seaweed)

• strong attatchment (limpets)

• form beds (mussels)

what determines the upper and lower limits of a species range in the intertidal

lower limit is biological factors (ex. predation or competition), upper limit is physical factors (ex. air exposure)

what is kelp why important

type of macroalgae, brown algae

• ecosystem engineer (shelter and food from detritus)

• wave action buffer (protects coastline)

• absorbs nutrients from runnoff

• comercially important

requirments for kelp forest (4)

hard substrate, cold temperature, lots of light, lots of nutrients (ex. temperate areas with upwelling)

how does El Nino affect kelp

el nino means less trade winds, less upwelling, less nutrients for kelp, warmer temperatures → more winter storms → less kelp

how do coral reproduce

assexually through polyps that break off, or sexually through broadcast spawning (releasing gametes into water column)

how do coral get nutrients

at night, the polyps they grab zooplankton from the water. but mostly, they get sugar from their mutualist endosymbionts (zooxanthellae) living in coral polyps

how do coral get their zooxanthellae

either from the polyp they grow from (when produced asexually), or from the environment NOT GAMETES

examples of mutualism in the coral reef

crabs and corals, clown fish and anenomes, sharks and remora fish

how does coral die?

its bleached when stressful abiotic conditions cause the zooxanthellae to eject themselves from polyps. without the endosymbionts the coral doesnt get nutrients and gets brittle. then bioerosion, wave action, hurricanes, boating, etc. break it away. also, algae grows over coral

threats to coral (7)

coral disease, surface temperature increase, eutrophication (less sunlight causes algae to take over), overfishing, coral bleaching, ocean acidification, acanthaster (sea star that eats coral)

pros and cons of broadcast spawning

pros: increases genetic diversity as gametes can go further
cons: low survivability of individual gametes, requires synchronous release, larvae must find substrate to settle

requirements for coral (6)

high light, stable warm temperatures (too cold, not enough CaC deposition, too warm, coral bleaching), low wave action, hard substrate, shallow, nutrient-poor clear water

progression of reefs

fringing → barrier → atoll

where is coral triangle

above Australia, east of SE Asia

describe atoll reef

goes up until reef crest, then drops down a bit to back reef

coral reef paradox and explanation

reefs have low nutrients but high productivity - efficient nutrient uptake and recycling of nutrients

what controls coral population?

bottom-up: nutrients
top-down: herbivores

patch reef habitat

habitat found in the back reef, more variation in temperature and salinity

5 adaptations of seagrass

• grow submerged

• high/varying salinity

• submarine pollination (asexual through rhizome fragmentation, sexually through seeds)

• compete w/ marine species

• anchor system

seagrasss distribution

mainly shallow coastal area

types of organisms that live on seagrass

infauna: burrow in sediment and filter/deposit feed
epiphytes: stems and leaves
epifauna: on the sediment
nekton: swim in canopy

why is seagrass important

nursery, accretion (slowed water causes suspended particles to fall out), export organic material (detritus)

threats to seagrass

excess nutrients, seagrass wasting disease, overfishing, excess grazing (some grazing results in more biomass (less diseases and epiphytes))

mangrove

flowering vascular plant that forms intertidal tropical forests

mangrove requirements (5)

calm, shallow, warm, salty water, anoxic/waterlogged soil

mangrove reproduction

animal-pollinated, can produce fruit and seeds
- vivipary: reproduction and growth of offspring while still attatched to plant (propogule), which then falls and is dispersed through water

mangrove adaptations (6)

• for high salinity: salt glands in leaves, salt filtration in roots, sequester salt in tissue

• for anoxic, water-logged soil: broad, shallow roots, air-projecting roots, tissues that store oxygen

mangrove importance

• accretion → increased water clarity

• nursery ground

• coastal projection

threats to mangroves

coastal development, shrimp farms, sea level rise

characteristics of epipelagic (4)

high light, low nutrients, low fish diversity, variable productivity

notable organisms/characteristics in the epipelagic (3)

N-fixing phytoplankton, fish with streamlined shape and counter-shading, patchy food = foraging over longe distances/depths, migrations

what is the most common ocean habitat?

deep sea

5 characteristics of deep sea

no sunlight, low temp, high salinity, high pressure, LOW PRODUCTIVITY

what do organisms in the deep sea eat?

mostly deposit feeders that feed on marine snow

3 sources of sediment

terrigenous (river, wind, glaciers), biogenous (marine snow, depended on productivity of epipelagic), authigenitc (metals)

what is the greatest stressor in the deep sea

competition for food

6 adaptations seen in the deep sea

transparency, BIG eyes, specialized predation, bioluminescence, miniaturization, huge growth

cold seeps

occur along tectonic margins, where gases and minerals are released into the water column

hydrothermal vents and what lives there

where cold water cracks hot rocks, creating “chimneys'“ that release hot water and precipitated metals
- tube worms, fish, crabs, chemoautotrophic bacteria

how long can whale falls provide nutrients to the deep sea community?

decades! scavenger and opprotunists stages 2 years each

methods for studying at depth

snorkel, scuba, hard-hat diving, ROV, submersible, ship with deep sea closing device

max sustainable yield

largest average catch that can be captured under existing environmental conditions

what is most sustainable seafood to eat?

kelp or algae or shellfish (ex. oysters, mussels)

Exclusive economic zone

“national waters”, within 200 miles of a country

high seas

“international waters” greater than 200 miles from land

types of data collection on fisheries

fisheries-dependent: fishing vessels, dock surverys
fisheries-independent: research vessels

fishery stock, examples of how to define

group of fish with definable attributes
- geography, migratory timing, genetic structure, life history

what life history traits are important to manage a fishery?

when fish reproduce, fecundity at different ages/sizes, males or females limiting, stock recruitment, population size, how fast fish grow

5 fishing strategies

angling, long-lines, gill net, trawl nets, purse seine

how to avoid bycatch (3)

• flags/streamers on the longline

• change hook shape

• bycatch exclusion device (ex. turtles)

where is most biomass and photosynthesis in a kelp forest?

canopy

what’s important about reef-building coral

use CaC to form hard skeletons, most affected by ocean acification (includes branching coral)

cnidocytes

cells containing nematocysts (stinging toxin injectors)

Which area of the rocky intertidal will have the greatest temperature stress?

High intertidal

In general, the upper limit of vertical zonation in the rocky intertidal is set by predation and the lower limit is set by physical stress in response to abiotic conditions.

False

All individual polyps of a single coral head are genetic clones. 

True

Under which of the following conditions would you expect coral reefs to thrive?

low sediment, low nutrient

acanthaster

“crown-of-thorns” starfish that predates on coral

The open ocean has low fish diversity relative to coastal areas.

True

Due to the Carbonate Compensation Depth, it is likely that sediments in the deepest areas of the ocean are comprised of a high proportion of CaCO₃.

False

The majority of fish are caught in the High Seas.

False

fishing down the food web

start by fishing predatory fish, but as their stock depletes shifting to planktivorous fish like sardines