OCG 420

exam 1

When does the sea become “deep sea”?

200 m

When light begins to dissipate and/or temp drops, shelf break

What zones are considered “deep sea”?

Mesopelagic (water column)

Benthic zone (sea floor)

Abyssalpelagic

What amount of Earth’s surface is considered deep sea?

97%, over 200 m

What are characteristics of deep sea environment?

Little to no light

High pressure

Low temperatures

High salinity

Well-oxygenated in most regions (colder water holds more oxygen)

Food limited with some exceptions

Stable salinity and temperatures

What is A?

Epipelagic

What is B?

Mesopelagic

What is C?

Bathypelagic

What is D?

Abyssalpelagic

What is an adaptation to make up for reduced seasonal signals and lack of food?

Food storage

What is the euphotic zone?

Sunlight rarely penetrates beyond this point

What is the dysphotic zone?

Sunlight decreases rapidly with depth, photosynthesis is NOT possible

Also known as twilight zone

What is the aphotic zone?

Sunlight does not penetrate at all, bathed in darkness

Contains bathypelagic, abyssopelagic, and hadopelagic zone

In which order do these zones go from least to most deep?

• Abyssopelagic

• Bathypelagic

• Hadopelagic

1. Bathypelagic (midnight) zone — 1000-4000 meters

2. Abyssopelagic (abyss) zone — 4000-6000 meters

3. Hadopelagic (hadal) zone — 6000 meters

What does L stand for?

Light intensity

What does k stand for?

Attenuation efficient

What does z stand for?

Depth

Depth of photic zone = (0.01)10

What can stabilize in the deep sea’s pressure?

Tri-methylamine N-oxide (TMAO)

Also found in fish tissue

How far has no fish been found?

Over 8400 meters

Deepest known is snailfish

What does thermohaline circulation bring?

Cold, salty, well-oxygenated water to the deep waters

How much of organic matter makes it to the seafloor?

1%

What is abundance?

Count of organisms

What is biomass?

Mass of organisms

What is the littoral zone?

Shoreline area

What do cold seeps produce?

Methane (CH4)

Can be acoustically detected

What are seamounts?

Underwater mountains formed by volcanic activity

Why are seamounts hot spots for fishing?

Seamounts upwelling nutrient-rich water which attracts more fish to the surface

How are mid-ocean ridges formed?

Plate tectonics, they are mountain ranges

Can break and make more seafloor

What is a black smoker?

Release of rich iron sulfides, vents pull in water from the deep sea through ridge/warm core which creates heat, thus creating chemical bonds

What are ocean trenches?

Features of subduction

Deepest in Atlantic is Puerto Rico trench

What is the azoic theory?

There is no life below 300 fathoms/550 m

Forbes hypothesized this

What was the demise of the azoic theory?

Charles Wyville Thomson cruised out to investigate distribution of deep sea life, chemical composition, physical properties in basins

Found life

What is satellite-derived bathymetry?

High spatial coverage, low resolution

What is multi beam sonar bathymetry?

Low spatial coverage, high resolution

What are some collective/destructive tools to study the deep sea?

• nets

• dredges

• trawls

• niskin/go-flo bottles

• benthic grabs

• sentiment cores

What are some observation/non-destructive tools to study the deep sea?

• Acoustic (sonar)

• Light (lidar) — short range

• Photography/videography

• Sensors (methane, temp, pH)

What are different ways we sample/observe the deep sea?

• lowering instruments on a wire

• freely descending landers and floats

• Vehicles (like tiny submarine) deployed from a ship

• Cabled observations — put on ocean floor surface, tiny vehicles help charge and bring up from the ocean 

How do nets collect samples?

• Collect samples in water column

• Can have various mesh sizes used depending on target organisms

• Have multiple opening and closing environmental systems (sensors can give out oxygen levels, pH levels, open and close certain nets)

• Environmental sensors

• Can sample at discrete depths

• Sleds

What are sleds?

Samples along the seafloor, can dig into it, environmental sensors, cameras attached

How are water samples taken?

• In niskin tables (1-30 L), individual deployment

  • Messenger slides down to button that releases spring, hence closes bottle

How do you take sediment samples?

• Box core

• Multicore

What is a box core?

Lead weights push box on floor and takes sediment up

A spade keeps it closed while going up

What is a multicore sample?

Lead weights push on floor, gets some water as well

What are benthic grabs?

• Directed sampling

• Target specific features and organisms

• Active heave compensated winch that helps stabilize cameras

What does CTD mean?

Stands for conductivity, temp, and depth

Refers to electronic instruments that measure these

Nistkin bottles

Why do niskin bottles and CTD rosettes have foam?

For buoyancy

What is an ROV?

Remotely operated vehicle

How do ROVs work?

Tethered to a ship by a cable and transmits video+ data in real time, videos get shown in a control room viewing

There is no limit to deployment time

What does single body system mean?

• One vehicle

• Tethered directly to ship

• More maneuverable 

What does dual body system mean?

• 2 vehicles on ROV, prevents camera shaking

• Provides spatial awareness by lights and cameras

What is a towsled ROV?

Lights seafloor below, has multiple cameras, reduces ship motion for exploration

What is an exploration ROV?

Neutrally buoyant, carries cameras and lights, equipped with manipulator arms

What are some types of sample collections from HOV/ROV?

• Cameras (stills,videos)

• Lighting (strobe, continuous)

• Manipulator arms

What are different types of manipulator arms?

• Suction tubes

• Coring device

• Sensors

• Soft robotics

• RAD sampler (traps live organisms)

What does AUV stand for?

Autonomous underwater vehicle

What are the pros of using AUVs?

Programmable

Lower costs

Great for mapping

Can operate a fleet

What are the cons of using AUVs?

Don’t know what they’re doing

Lots of training

Modify missions

What kind of data do AUVs collect during seafloor surveying?

Multibeam sonars

Photographs (stitch photos together for comprehensive view)

Physical and chemical datas

What is a nutrient?

Dissolved molecules that can be taken up by microbes and some invertebrates

IE — nitrate, ammonium, phosphate, metals

What is a particulate?

From organisms and dead matter

IE fecal pellets, marine snow

What is a DOM?

Dissolved organic matter

Bacteria good at consuming dissolved organic matter

What is a POM?

Particulate organic matter

How does photosynthetic primary production work?

Light energy used to convert inorganic nutrients and CO2 into organic compounds, cell and growth reproduction

Where does photosynthetic net primary production go?

Trophic level

What zone makes primary and secondary production?

Photic zone

What 2 zones produce secondary production?

Disphotic zone and aphotic zone

What is phytodetrius?

Aggregated senscent/dead phytoplankton

What is considered particulate organic carbon? (POC)

• Phytodetrius 

• Fecal pellets

• Mucus nets (discarded Larvacean houses)

• Sloughed off cellular materials

What is in canyon biodiversity?

• Coral and sponges

• Methane hydrates

• Marine litter

What animals first eat whale falls?

Sharks, rattail fish, black hagfish

What animals come second to eat whale falls?

Anemones, sea stars, mollusks, worms, crustaceans

What animals come last to eat whale falls/leftover bones?

“Bone eater snails” and “bone eating worms/zombie worms” 

How much food is in the epipelagic zone?

80%

How much food is in the mesopelagic zone?

20%

How much food makes it to the seafloor?

1%

What are different biological pumps?

• Mixing pump (physical transport)

• Gravitational pump (slower, shrinks due to density)

• Migrant pump

What are quantitive sampling tools?

• Cores/samples from floors

• Nets

• Niskin bottles

• Photo/video survey

What is surface productivity?

measures the production of carbon

What is benthic biomass?

How many organisms live on the seafloor

What is taxonomic diversity?

Number and variety of species

What is functional diversity?

Number and variety of biological processes, functions, or characteristics of an ecosystem

What is richness?

Number of species in particular area, no regard of species dominance or distribution

How can you tell you have fully measured species richness?

When the lines/data stop climbing/rising, stay in a similar line

What is species evenness?

Number of individuals in each species

How can you find species diversity?

Number of species, weighed for relative abundance, which is a combo of richness and evenness

What depth has the greatest diversity?

Moderate depths

What graph shape shows diversity-depth relationships?

Unimodal, peak in center

What is PDR?

Productivity-diversity relationships

What populations are prone to extinction?

Lower diversity with low productivity

What zone is called the twilight zone?

Mesopelagic zone

What is the only source of light in the deep sea?

Bioluminescence

What is different about silver spiny fin fish eyes?

Can see in the dark and in color

What color often appears under white light?

Red

What kind of camouflage is common in the deep sea?

Ultra-black skin

Reflect <0.5% of light and/or darkness to blend into ocean

What color is most common in bioluminescence?

Blue-green light, transmits best in water

What percent of pelagic organisms are thought to be luminous?

76%

What percent of benthic organisms are thought to be luminous?

30-40%

What is bioluminescence?

Light produced by an organism via chemical reaction

What is luciferin?

Molecule that produces light

What is luciferase?

Enzymes that catalyzes reaction