marine biology exam #1

physiological oxygen balance

a crucial skill for all organisms means that O2 supply must be equal to O2 demand

why is O2 balance in cephalopods interesting?

Cephalopods have:

* high O2 demand from metabolic rate
* very high growth rates
* jet propulsion
* more limited O2 supply

Fishes have:

* lower growth rates
* undulatory fins

Both have:

* active locomotion
* visually oriented predation


* large brains and complex behaviors

what is marine biology?

* the scientific study of life in the ocean
* the science of biology applied to the ocean rather than separate science
* different than (but complementary to) exploring the ocean or marine animal care

the important of marine life

* the ocean is 99% of earth’s biosphere by volume
* there are many different lifeforms and strategies for surviving within this massive space
* where’s the largest migration on earth?
* in the ocean
* organisms have huge impact on ocean chemistry and geology
* marine life provides 50% of oxygen to the atmosphere
* >40% of human population relies on ocean for significant source of animal protein
* 10-12% of human population depends on fisheries/aquaculture for livelihood

marine biology vs oceanography

* marine biology focuses on how marine organisms survive in the marine environment
* ‘oceanography’ focuses on the marine environment in which marine organisms survive
* this marine biology course will grow your understanding of marine organisms and biodiversity

why study marine biology?

* personal experiences
* conservation
* fisheries and policy
* medical and biotechnology
* recreation

the science of marine biology

Charles Darwin

* HMS Beagle for 5 years (1831)
* studied barnacles and atolls

The Challenger expedition

* first major oceanographic expedition
* funded by the British government
* set off in 1872, under scientific leadership of Charles Thompson
* sailed around the world for 3.5 years

marine biology from the shoreline: growth of marine labs

* seashore provides easy access to marine life
* permanent facilities began to appear
* first marine lab: stazione zoologica in naples, italy, 1872
* first major American marine lab: Marine biological laboratory at woods hole, massachusetts (had majority women workers)

ocean technologies

* SONAR: developed in WW2
* SCUBA: refined after WW2
* high-tech subs: ALVIN (recorded the Titanic)
* unique vessels with interesting technologies: R/V Flip
* undersea habitats: Aquarius
* modern additions:
* computers and electronics
* satellites
* ROVs: remotely operated vehicles
* AUVs: autonomous underwater vehicles
* crittercam
* environmental DNA

scientific method vs reasoning

1. induction vs reasoning


1. deduction: idea - observations - conclusion
2. induction: observations - analysis - theory
2. hypothesis vs theories
3. ‘the scientific method’

physical parameters of interest to marine organisms

* light
* temperature
* salinity
* pressure
* oxygen
* pH
* nutrients
* continental shelf

light

* seawater is relatively transparent, critical to photosynthesis
* not all wavelengths of light penetrate equally
* clear ocean water is most transparent to blue light but other colors get absorbed faster
* the depth that a given wavelength can reach is a function of sun position, cloudiness, and water turbidity
* in the open ocean, irradiance falls an order of magnitude every 75 meters until it is gone by =1000m

transparency

* strongly affected by suspended and dissolved materials
* sediment, plankton, etc, reduce transparency
* coastal waters often contain material that absorbs blue light so that green penetrates deepest
* can be measured with sophisticated equipment throughout the water column
* Secchi disk for quick measurement in shallow water (black and white disk on weighted string)

temperature

* sea surface temperature (SST) varies based on sun exposure and currents
* -2 C < SST < +30 C
* most SST measurements are all made via satellite and available on a daily basis online
* wind and waves maintain a ‘mixed layer’ at the surface
* below the mixed layer depth, temperature declines exponentially in the ‘thermocline’
* below the thermocline the ‘ocean interior’ is cold

salinity

substances dissolved in seawater come from:

* weathering of rock on land
* hydrothermal vents
* volcanoes, enter as rain and snow

salinity calculations

only 6 ions make up >99% of the ions dissolved in seawater:

* Cl-, Na+, SO4 2-, Mg2+, Ca2+, K+ (Na+ and Cl- over 85%)

salinity is a measure of total amount of salt dissolved in seawater (no just NaCl)

* measured traditionally as grams of salt per 1000 grams of seawater
* 35 grams of salt in 1000 grams of seawater is a salinity of 35 parts per thousand (ppt)
* today, measured electronically, conductivity meter, units of practical salinity units (PSU) but equivalent to ppt

rule of constant proportions

* relative percentage of the major ions in seawater remain constant even when the total amount of salt varies from place to place, which means salinity differences are not due to addition or removal of any particular ion/ions
* so what then typically causes the variations in total salinity we see at times? how is freshwater added? how is freshwater removed? why aren’t icebergs salty? how does ice formation affect salinity of the remaining seawater?

salinity variation

average salinity of ocean is 35 ppt

* open ocean 33-37 ppt, pretty stable
* partially enclosed seas can be more extreme
* ex: Red sea is hot, dry, and evaporation dominates over precipitation so the salinity is around 40 ppt
* ex: Baltic sea has river runoff that gives it a typical salinity of only about 7 ppt

is the Arctic or Pacific saltier?

FINISH

Pressure

* organisms on land are under 1 atmosphere of pressure at sea level (the weight of all the air above them)
* marine organism are under weight of water in addition to air (and water is much heavier)
* with every =10m (=33 ft) depth, another atmosphere of pressure is added
* abyssal plains @ 4000m = 400 atmospheres
* mariana trench = 1110 atmospheres

organisms are mostly water

* water is incompressible but as pressure increases, gasses are compressed
* air bladders, floats, and lungs shrink or collapse
* if deep sea creatures breach the surface too fast they inflate

oxygen

* enters the ocean through gas exchange with the atmosphere
* mush less soluble in water than air
* solubility influenced by temperature and salinity
* photosynthesis drives dissolved oxygen increase
* respiration drives dissolved oxygen decrease
* balance between photosynthesis and respiration
* at the surface, O2 is nearly always in equilibrium with the atmosphere
* but deep ‘old’ water often has less O2

pH (measures acidity)

* pH = -log10 (H+)
* 95% of seawater buffering capacity is from the CO2 system
* also driven by photosynthesis and respiration
* average open ocean sea surface level pH = 8.1
* coastal environmental much more variable

CO2 system =

* CO2 (carbon dioxide)

nutrients

* when talking about the oceans, ‘nutrients’ is not a vague term for ‘food stuff’
* nutrients are chemicals that can limit primary production (ex: algae/phytoplankton growth), limiting therefore, worth being tracked
* Nitrate (NO3-) is the most common limiting nutrient for primary productivity
* but can be phosphate (PO4^3-) or even iron
* nutrients typically accumulate with depth

continental shelf

* only about 8% of the ocean’s surface area but teaming with life compared to much of the ocean
* width varies from 1km (0.6mi) to 750km (470mi)
* ends at the shelf break at a depth of 120-400 m (400-1,300ft)

consequences of defining the shelf break

melting arctic opens up newly accessible oil deposits but there is a UNC that limits the continental shelf

physical phenomena of interest to marine organisms

* wind patterns
* surface currents
* thermohaline circulation
* waves
* tides
* climate oscillations

wind patterns

warm air rises from equatorial regions but air blows in to replace rising air, creating trade winds

Coriolis effect

deflection of moving mass relative to Earth due to the earth’s rotation

Coriolis effect causes:

* right-ward shift in northern hemisphere
* left-ward shift in southern hemisphere

surface currents

* winds push the sea surface which creates currents
* instead of going in same direction, water moves off at and angle of 45 degrees due to Coriolis effect
* motion is transmitted to deeper and deeper layers, each offset due to Coriolis until too little energy remains
* eventually, at a depth of a few hundred meters at most, the wind is not felt at all
* currents can vary from day to day, with season, weather, etc
* on continental shelf, currents affected by bottom, shape of coastline, and tides
* most examples come from average patterns over large distances and time spans

Ekman Transport

as a whole, the sea surface moves at a 90 degree angle from wind direction

major surface currents

* Japan vs California
* North Carolina vs Straight of Gibraltar (Mediterranean entrance)
* eastern Australia vs Chile (western South America)
* western South America vs eastern South America

Thermohaline circulation

* because dense water sinks, the ocean is usually layered or stratified (3 main layers)
* density strongly influenced by temperature, hence the mirrored profiles
* polar water is cold (=dense) and ice formation also increases salinity (=density)

downwelling

at the poles, surface water can sink

wave structure

* surface waves driven by wind
* height and wavelength are determined by wind strength/direction

particle movement in water

* although energy travels, organisms (ex: plankton) or water itself do not
* but in reality propagation along with wave due to friction
* if deep enough, even the strongest storms can’t be felt by marine organisms

wave progression from storm winds

* as waves approach shallow water, circles become ellipses
* waves slow down and stack up until they tip over = surf

tides

centrifugal force pulls things away from the axis of rotation

earth spins on its own axis

moon moves slightly during the 24 hour rotation

sun also impacts tides

* spring tide: gravitational pull of moon plus sun
* neap tide: gravitational pull of sun

types of tides

* land masses make tides more complex in reality
* depending on where you are in the world tides may be either semidiurnal (even highs), mixed semidurinal (uneven highs), or diurnal (flat)

climate oscillations

* occur on different timescales
* annual - decadal
* ENSO (El Nino), NAO (North Atlantic Oscillation), PDO (Pacific Decadal Oscillation)
* 100,000 years
* glacial-interglacial cycles

glacial-interglacial cycle

* cycle every 100k years or so
* during glacial periods, lots of ice, forms
* with water sequestered in ice how does sea level change?

ingredients of life

* water
* ions and small molecules
* macromolecules
* proteins
* nucleic acids
* carbohydrates (polysaccharides)
* lipids

all needed for storing and using energy

carbohydrate facts

* structure: C, H, O sugars, can be simple or chains
* function: many functions, energy storage, signaling
* examples: glucose, chitin, cellulose

lipid facts

* structure: hydrophobic (in parts) due to C-H chains
* function: energy storage, membranes (compartmentalize cells)
* examples: phospholipids, cholesterol

protein facts

* structure: amino acids in long chains with side groups
* function: many functions
* examples: Na+/K+ ATPase, hemocyanin, luciferase

nucleic acid facts

* structure: nucleotides in long chains forming helix
* function: gene storage and regulation
* examples: DNA, mRNA, miRNA, tRNA

primary production

* photosynthesis produces glucose, a simple carbohydrate
* the glucose is used to make other materials for the organism to grow and reproduce
* the new organic material created as the organism grows and reproduces is primary production

fuel of life

* respiration (burning the fuel)
* sugars are broken down using oxygen, releasing CO2, water, and chemical energy

challenges of life in the sea

* salinity
* temperature

the problem with salinity

* the salinity of the ocean means that many more ions are dissolved in it than freshwater ecosystems
* these ions can affect the metabolism of marine organisms, as many enzymes and other molecules are very sensitive to ion concentration
* the ions are subject to the rules of diffusion

diffusion

* with no way to control the movement of molecules into or out of the cell, the concentration of all ions in the cell would eventually match that of the seawater
* using a selectively permeable cell membrane the cells can maintain the correct ion concentrations to carry out metabolic processes

osmosis

* water molecules also diffuse from areas of high concentration to areas of low concentration
* diffusion of water across cell membrane is the process of osmosis

concentration of water molecules is affected by the concentration of solutes in the water

more solutes = fewer free water molecules so water travels from areas of lower solute concentration to areas of higher solute concentration

osmosis conditions

* lower concentration on the outside means water moves in cell
* same concentration inside and outside means there is no water movement
* higher concentration on the outside means water moves out of the cell

how to control the balance of ions and water to prevent damage to cells?

two strategies as environmental salinity changes includes osmoconformers and osmoregulators

osmoconformers

allow their blood to change saltiness but alter the concentration of organic osmolytes such as carbohydrates (ex: glycerol), amino acids (ex: canonical, taurine), and methylammonium solutes (ex: TMAO, trimethylglycine) in their cells. these are compatible with proteins and counter osmosis.

osmoregulators

maintain stable blood salt concentrations by pumping ions out of their blood back into seawater

temperature challenges

* water conducts heat 20x faster than air
* organisms are greatly affected by temperature
* metabolic reactions proceed faster at high temperature and slow down at cold temperatures
* organisms evolve enzymes suitable for specific temperature ranges

marine organisms & temperatures

* marine organisms are often restricted to specific regions that correspond to average water temperatures
* the boundaries are not absolute and change slightly with the seasons and shifts in current patterns
* organisms have different strategies and abilities for dealing with changes in temperature

classification of animals by their response to changes in external temperature

* ectotherms
* endotherms
* poikilotherms
* homeotherms

ectotherms

most metabolic heat is rapidly lost to the environment; body temperature matches external temperature

endotherms

retain significant metabolic heat; maternal temperature stays warmer than external temperature

poikilotherms

temperature varies with external temperature

homeotherms

regulate body temperature so it doesn’t vary as much as external temperature

what is ectothermic and poikilothermic?

invertebrates, most fishes, and marine reptiles

what is endothermic and poikilothermic?

some large sharks, tunas, and billfishes

what is ectothermic and homeothermic?

nothing

what is homeothermic and endothermic?

mammals and birds

asexual reproduction

* reproduction by one individual, no involvement of partner
* offspring are exact clones (other than new mutations)
* ex: cell fission (many plankton), budding (anemones), runners (seagrass)

sexual reproduction

* reproduction involving combination of genetic material from 2 individuals
* creates variety in offspring
* most marine organisms pass through a larval stage before reaching maturity

reproductive strategies

the particular combination of reproduction methods used by a given species

different reproductive strategies

* broadcast spawning: little parental involvement
* incubating eggs (more investment)
* long term care to developing young
* reproduction via flowering

what does it mean when we say that two particular species are related?

means that they share a common evolutionary history aka phylogeny which means hat both groups evolved from a common ancestor which means that both groups evolved from a common ancestor

microbes

* bacteria, eukaryota, archaea, viruses, prokaryotes, microalgae, protozoans, fungi
* microbes are as diverse and unrelated as you can get
* they live everywhere in the ocean (tide pools, open ocean, under the seafloor)
* unifying feature is small size
* most important primary producers in the ocean

virus features

* particle not made of a cell so therefore it is not alive
* consist of genetic material and protein coat (caspid)
* parasites that develop and reproduce only when infecting host
* 20-200nm (most can be seen with most powerful microscopes)

significance of viruses

* most abundant and diverse ‘life-like’ particles in the ocean (10^3-10^7 viruses/mL seawater)
* killing cells → dissolved organic matter (DOM)

virus affects on other marine life

* 90% of viruses infect bacteria
* mollusks and crustaceans of commercial importance
* fishes, sea turtles, marine mammals
* oysters and mussels that filter hepatitis from sewage can infect human eating them

prokaryotes

two domains: bacteria and archaea

differences between bacteria and archaea

cell walls and membrane composition differ, protein production pathway differ

prokaryote facts

* seawater up to = 1 million bacteria/mL
* abundant everywhere in the ocean
* spheres, spirals, rods, rings
* most bacteria are few um in diameter (1000 um = 1mm)
* not all archaea are extremophiles, many are abundant everywhere

cyanobacteria

* many different kinds of prokaryotes produce organic carbon for primary production but the most abundant is cyanobacteria
* ‘blue-green algae’ but is not an algae
* the most abundant photosynthetic organisms on the planet (more than algae, more than plants)
* the Great Oxidation Event put oxygen in the air for the first time and almost killed everything 3.5 billion years ago

chemoautotrophy

not just photoautotrophy, bacteria in hydrothermal vents that use H2S rather than light

critical roles in nutrient cycle

* main consumers of dissolved organic matter (DOM) and particulate organic matter (POM)
* decompose dead organic matter back to nutrients so it’s bioavailable again for primary producers

types of microalgae

diatoms, dinoflagellates, coccolithophores

algae

* eukaryotic, chloroplast-containing organisms
* most photosynthesize but some eat food particles and some do both
* although single-celled, can form colonies and huge blooms
* commercially used as food, salmon feed, bioplastics, etc

microalgae DMS

* many microalgae are rich in DMSP as an organic osmolyte and can convert to gaseous DMS
* DMS can attract predatory grazers and have a rotting seaweed smell

microalgae vs macroalgae

* micro = unicellular
* macro = multicellular

diatoms

* extremely prolific planktonic primary producers
* produce more O2 and capture more CO2 than all rainforests on earth combined
* individuals so small you need a microscope but blooms so large they can be seen from space
* 40-50% of global marine primary productivity
* their shells compose much of silicious sediment on the ocean bottom that can be harvested for dynamite and cat litter
* oil droplets help maintain buoyancy

diatom groups

2 broad groups:

* radial symmetry = centric
* bilateral symmetry = pennate

frustule

* diatom cell covered by 2 silica (SiO2, glass) shells forming a frustule
* holes in the frustules allow light, gases, and nutrients in but waste out

dinoflagellates

* two flagellae: one around the groove, the other trailing behind
* shell (when present) made of cellulose
* half are photosynthetic and half ingest food
* some form harmful algal blooms in the coastal regions (ex: red tide)
* others are bioluminescent
* still others are symbionts with corals and other animals (zooxanthellae)

coccolithophores

* unicellular with 2 flagella
* cover cells with multiple coccolith shells
* coccoliths are made of calcium carbonate (CaCO3)
* biggest producer of limestone (type of CaCO3) in the oceans

diatom facts

* shells made of silica
* morphology is geometric

dinoflagellate facts

* shells made of cellulose
* morphology is structures with whips and horns

coccolithophore facts

* shells made of calcium carbonate
* those ones with all the plates