Oceanography Final

What three domains is life divided into?

Eukaryotes, Bacteria, and Archaea

Distinctions between eukaryotes, bacteria, and archaea

Bacteria and archaea have no cell nucleus and are called prokaryotes. Eukaryotes have a cell nucleus.

Prokaryote vs Eukaryote

Prokaryotes are single celled organisms. Eukaryotes can be single cell organisms (protists) and multicellular organisms.

Classification by carbon and energy source:

1. photoautotroph: Carbon and light energy source
2. chemoautotroph: carbon and inorganic chemical energy source
3. photoheterotrophs: organic compounds and light energy source
4. chemoheterotrophs: organic compounds carbon source and organic compound energy source
5. \

Photosynthesis vs Respiration

co2+ h20 -→ sugar and o2

\
o2+ sugar -→ co2 + h2o

Habitatable Zones of the Seafloor

pelagic (in the water) and benthic (on/in the seafloor),

neritic (on the shelf) and oceanic (off the shelf),

photic (light) and aphotic (no light), litoral (shelf tidal zone), sublitoral (shelf below tidal zone)

Organism Subdivisions

plankton (drifting in water),

nekton (actively swimming in water), neuston/pleuston (at the water/air interface),

benthos (at the sediment/water interface).

Plankton

Plankton comprises primary producers (phytoplankton = photoautotrophs) and consumers (zooplankton = chemoheterotrophs) and can be categorized in different size spectra from femto (viruses << μm) and pico (procaryotes and very small algea \~μm) to mega plankton ( e.g. salp chains up to some meters).

Trophic levels

describe the position of an organisms in a food chain/web. The basis of the (surface) ocean food chain starts with

photoautotrophic bacterio- and phytoplankton, which is consumed by heterotrophic zooplankton. Together they form the plankton. Further up the food chain we find nekton (fish etc.) that feed on the zooplankton. Because some nekton also feeds on phytoplankton, trophic levels in the oceans are best described in webs rather than in chains.

How does phytoplankton conduct photosynthesis

uses the light of the sun (blue and red wavelengths) with the chlorophyll pigment to conduct photosynthesis.

How is plankton diverse?

Phytoplankton is diverse also with regard to other chemical specialties. For example, some form carbonate shells, others produce toxins and others are able to fix nitrogen (N2).

How can primary productivity be inferred?

Primary productivity can be inferred from satellite images of chlorophyll distribution and by dark/light incubations of seawater with organisms (measuring oxygen production/consumption).

Photosynthesis at compensation depth vs critical depth

At the compensation depth, photosynthesis equals respiration. At the critical depth, photosynthesis integrated over the entire water column equals their total respiration.

What limits primary productivity (photosynthesis) of phytoplankton?

Its limited by the penetration of light into the ocean

Light penetration in water

Different parts of the light have different penetration depths into water (blue deepest, red shortest in clear water).

Why does light penetration in the water vary?

a) amount of particles in the water that absorb/reflect light

b) seasonality (particularly at high latitudes)

c) sun vs. moon light.

Redfield Ratio

Primary production (photosynthesis) takes up carbon, nitrogen and phosphorous in a 106:16:1 ratio.

Key macro nutrients for phytoplankton

nitrate, phosphate and (for diatoms) silicate. They are strongly reduced (bio-limiting) in the surface ocean.

Primary production in the Southern ocean

primary production is low compared to the availability of macro nutrients. The reason is the lack of iron, a micro nutrient (trace element).

Main source of marine snow

Phytoplankton is the main source of marine snow, which delivers organic carbon to the deep ocean.

What is an important link between phytoplankton and higher levels of consumers (predatory nekton)

Zooplankton

Biomass of zooplankton

is directly coupled to phytoplankton. Their biomass usually peaks shortly after phytoplankton blooms.

Zooplankton and their vertical migration

Zooplankton conducts daily vertical migrations (at surface at night, in the twilight zone during the day).

Important mechanism of organic matter

Sinking fecal pellets of zooplankton

Nekton consists of what

vertebrates (fish, some reptiles, some birds, mammals), mollusks (such as squid), and crustaceans (like the swim crab).

What occupies the higher consumer levels in food chains.

Nekton. If the top consumer feeds directly on the primary consumer, food chains can be very short (phytoplankton à krill à baleen whale). In other cases food chains consists of several levels of nektonic consumers.

When nektonic animals die:

they can sink fast to the deep ocean (if not consumed by predators). Here, they form large food falls, which is an unusual large arrival of organic matter provided to the deep-sea community.

What does the biological pump do?

binds carbon (from CO2) into biomass (Soft-Tissue Pump) and carbonate shells (Carbonate Pump) and exports it from the surface to the deep ocean.

What does the physical pump do?

dissolves CO2 from the atmosphere and transports it to the deep ocean at places of deep-water formation. In coastal upwelling regions CO2 (atmospheric + recycled) is released from the ocean back to the atmosphere.

Remineralization

the process of converting organic material back to inorganic substances (CO2 + nutrients). It is interchangeable with the term respiration.

What happens to carbon in the water column?

organic carbon can be either remineralized within the surface ocean via the microbial loop (mostly DOC consumption) or it can be exported to the deep ocean as POC (marine snow, fecal pellets).

what happens to particle flux and organic carbon with water depth?

The sinking particle flux decreases with water depth, due to continuous remineralization during transport. The amount of labile (easy digestible) organic carbon also decreases with depth.

Oxygen Minimum Zones

In nutrient-rich (hence very productive) coastal upwelling regions, organic carbon degradation in the water can be so high that oxygen declines dramatically, creating Oxygen Minimum Zones (OMZ)

How much organic carbon reaches the seafloor?

It depends on the productivity at the surface and the water depth.

Organisms that feed on organic carbon at the seafloor are: \n

(1) Suspension Feeders, (2) Deposit Feeders, (3) Prokaryotes.

Microbial biomass in sediments:

declines exponential with water depths and linear with POC flux.

The benthic microbial organic carbon turnover:

The benthic microbial organic carbon turnover is highest on the shelf and lowest in the deep sea. Though, shelfs represent only the minority of the ocean seafloor.

Bioturbation (mixing) and bioirrigation (ventilation) by animals stimulates:

microbial organic matter degradation in sediments (think of the earth worm in soil as an analog).

Co2’s return to the atmosphere

CO2 is returned to the atmosphere within days from the euphotic zone, but within centuries from the deep sea (remember: ocean conveyer).

CO2 in deep water

During its travel through the oceans, deep water accumulates more and more CO2 that is released from recycling processes. Hence, the oldest deep water (Pacific Ocean) carries the largest amount of CO2 (DIC).

Intertidal zones

Intertidal zones reach from the high tide to the low tide line. The tidal difference can be small or large, the environment can be rocky, sandy or muddy. Organisms living within tidal zones are exposed to harsh extremes (high/low salinity and temperature, physical forces).

Intertidal zones:

spray zone, upper intertidal, middle intertidal, lower intertidal and tide pools.

Sandy beaches

they show different zones determined by wave action: back beach, beach berm, beach face, wrack zone, and shore bars. There is a community of animals lining at sandy beaches either in kelp debris of the wrack zone, inside the sand or preying.

Tidal mudflats

Tidal mudflats are coastal wetlands that form when mud is deposited by tides. Organisms living in mudflat need to anchor or burry themselves to the constantly shifting substrate. Mudflats are the home to seagrass, clams and worms.

What are mudflats followed by?

Towards the inland, mudflats are often followed by salt marshes. Plants living here are adapted to live in a saline environment. Their presence support the trapping of mud. Salt marshes are a nursery for fish and home to many birds that rest and breed here.

Kelp Forests

Kelp forests are one of the most productive ecosystems on Earth. Some kelp can grow up to 60 cm per day. There are two major types of kelp world-wide: Macrocystis and Laminaria. Kelp consist of holdfast, stipe, blades and bladders. While kelp is a foundation organisms that provides the habitat for the community, sea otters are keystone organisms that protect the kelp forest function by feeding on the kelp consumer, i.e. the sea urchin.

Corral Reefs

Coral reefs are one of the most diverse ecosystems on Earth. They are only found about 30 ̊ north and south of the equator due to their temperature optimum, and only to a max. depth of 50 m due to their light requirement for their photosynthetic symbionts.

What do corrals consist of?

Corals consists of colonies of small polyps embedded in calcium carbonate shells. They live in a symbiotic relationship with zooxanthellae, single-celled dinoflagellates.

Corral over time:

Over time, coral organisms create massive reefs of different types (often consecutively): fringing reef, barrier reef, atolls.

Coral Reef food web

start with pelagic phytoplankton, which is consumed by zooplankton and corals. Top predators include sharks.

Coral reef value

Coral reefs have a large economic value and provide services for the fishing industry, tourism, medicine, and costal protection.

Coral Bleaching

Coral bleaching is the phenomenon when the algae symbiont leaves the stressed coral. Without the symbiont, the coral can't survive very long and eventually dies. Major cause of world-wide coral bleaching phenomena is the rise in ocean temperature, but it can also be triggered by pollution, strong exposure to sunlight or extreme low tides.

“Chasing Coral”

Netflix documentary documenting a world-wide bleaching event of corals.

Arctic vs Antarctic

The Arctic is an ocean surrounded by land, the Antarctic is a land mass surrounded by ocean. The Arctic has thick multi-year sea ice, the Antarctic has thin young sea ice. Polar bears live only in the Arctic, Penguins live only in the Antarctic.

Common animals of the arctic

harp and ribbon seals, walrus, narwhal, beluga whale, bowhead whale, polar bears, polar fox and Greenland sharks

Common animals of the antarctic

emperor and adéle penguin, Weddell seal, baleen whales, orcas, sea leopards and large benthic fauna such as sponges, anemones and echinoderms.

When sea ice forms:

it excludes salt and creates brine channels that provide an ecosystem for sea ice biota, which includes algae, bacteria, protists, and small crustaceans that can live under these high salinity conditions. Gradients of light, temperature, and salinity can be very steep in sea ice. Sea ice biota are an important part of polar food chains. Possible consequences of sea ice melting (due to Clime Change) for polar ecosystems are currently unknown.

The deep sea

is dark, features high pressures and low temperatures, and is generally food limited, because it depends on food provided by the euphotic zone. Only about 3% of organic matter produced in the euphotic zone reaches the abyssal plains. Animals living in this environment have adapted to these harsh conditions.

Bioluminescence

is the emission of light by a living organisms. It is created by the reaction of an enzyme (luciferase) with a molecule (luciferin). Bioluminescence is used to warn, lure or communicate in the dark environment.

What do deep sea organisms avoid?

gas-filled body cavities and have soft and flabby bodies to cope with the high hydrostatic pressures.

Cold temperature in the deep sea makes organisms:

growing slow and exhibiting longer lives due to their reduced metabolism.

Deep sea organisms feeding habits

Some deep-sea animals feed entirely on marine snow, such as the vampire squid and the crinoids. Other animals are predators and have developed efficient ways to lure (bioluminescence), capture (long teeth) and engulf (large mouth and stomach) prey. Some of these effective predators include the anglerfish, viperfish, hatchetfish and gulper eel. Other animals have specialized in scavenging on larger carcasses. They effectively locate their food and are able to ingest large amounts of the rare feast. Such organisms include amphipods, hagfish, sleeper sharks, and crabs.

Hydrothermal vents

At hydrothermal vents seawater is heated through volcanic activity and is released with reduced chemical species. Black Smoker release iron sulfides, white smokers release minerals including calcium and magnesium. Hydrothermal vents are found at plate boundaries (particular ocean spreading zones) and hot spots.

Hydrogen sulfide released from vents

Hydrogen sulfide released from vents support chemosynthesis by bacteria that oxidize sulfide to sulfate. This process provides the basis for a very productive vent ecosystems. Some animals like tubeworms, clams and mussels live in symbiosis with chemosynthetic bacteria and have completely reduced their digestive system.

Cold Seeps

Cold seeps are places where hydrocarbons (methane and oil) rise from deeper reservoirs in the sediment to the seafloor. Cold seeps are often associated with subduction zones or over-pressurized systems that open pathways for hydrocarbon migration.

Bacteria and archaea at cold seeps

At cold seeps, bacteria and archaea consume methane and oil and breath sulfate, which they reduce to hydrogen sulfide. Similar to hydrothermal vents, the sulfide provides energy for chemosynthetic communities, including free-living sulfur bacteria and symbiont tubeworms, clams and mussels.

Whale falls

When large whales sink to the deep sea ('whale falls'), they create a food bonanza, which is, in a first stage, exploited by mobile scavengers such as hagfish, amphipods, and sleeper sharks. Depending on the size of the whale, this period can last up to two years.

Opportunistic stage

After most of the whale biomass has been consumed by scavengers, the opportunistic stage starts, which features high abundances of a few opportubnistic organisms, such as crabs and polychaete worms, that feed on biomass from bones or that has been transferred to the sediment. This stage may also last up to two years.

Sulfophilic stage

The third stage of the whale represents the sulfophilic stage, in which bacteria that consume whale biomass in sediments and inside bones (bone lipids) generate hydrogen sulfide by breathing sulfate. The hydrogen sulfide (similar to hydrothermal vents and cold seeps) provides the energy basis for a chemosynthetic ecosystem at whale falls, including free-living sulfur bacteria, and symbiont tubeworms, clams, and mussels. This stage can last up to 50 years.

Stepping stone for the spreading of specialized chemosymbiont fauna?

Because some chemosynthetic fauna between whale falls and cold seeps and hydrothermal vents overlap, it was hypothesized that whale falls could serve as stepping stones for the spreading of specialized chemosymbiont fauna.

Damage caused by commercial whaling

It is currently unknown how much damage the reduction of the whale population by commercial whaling did to deep sea ecosystem, because we have no good records of deep-sea ecosystem diversity prior to whaling.

The world depends on:

The world still largely depends on fossil energy resources such as oil, gas, and coal. They are used, e.g., for transportation, heating, electricity generation, chemicals and pharmaceutical products. The United States are the world top consumer of oil and gas.

Fossil fuels

As the name implies, fossil fuels are energy resources that were formed in the past. Fossil oil and gas reservoirs form from deposited organic matter in the seafloor (dead algae etc.) over millions of years. Fossil fuels are produced much more slowly than humans consume them. Humans will therefore run out of fossil fuels in the near future.

Why has there been deeper drilling stations?

The demand for fossil fuels pushes oil and gas production to deeper and deeper drilling stations in the deep sea, which technically increases the risk of oil spills, such as the Deepwater Horizon oil spill in the Gulf of Mexico. The melting of sea ice in the Arctic Ocean encourages several countries (including the US) to expand oil production. But the Arctic Ocean ecosystem is more sensitive to oil spills than warmer regions. Oil spills take decades to disappear (see Exxon Valdez disaster) and accumulate in food chains.

Mineral resources of the seafloor

The ocean seafloor harbors different mineral resources such as manganese (= polymetallic) nodules, cobalt crusts and volcanogenic massive sulfides.

Manganese nodules

Manganese nodules grow at the abyssal plains when metal compounds dissolved in water precipitate around a nucleus. They have been found to contain a significant amount of rare earth elements. We use rare earth elements in cars, industry motors, electronic devices (smartphones, TVs) etc. While they are not really rare they are rarely found in high concentrations. China is currently the largest producer of rare earth elements. Production of manganese nodules could be accomplished by harvesting machines that vacuum the nodules from the seafloor and pump them to a ship. But this procedure could have multiple negative effects on the deep-sea environment.

Massive sulfides

Massive sulfides form at hydrothermal systems (black smokers) when dissolved metals are expelled and react with sulfide to form minerals, which precipitate and sink to the seafloor to form massive layers. Massive sulfides, aside from other metals, have been found to contain significant amounts of silver and gold. The harvesting of massive sulfides, particular from active black smokers, could have dramatic effects on hydrothermal vent ecosystems.

Fishing Industry

Humans depend on proteins from fish, but with the increase in population, the demand for fish is increasing, reaching levels of fish exploitation above sustainability. Today, more than 70% of all world fish populations are unsustainably overexploited.

Effects of fishing

One side-effect of fishing is the catch of non-target fish and ocean wildlife (bycatch). Some fishing methods catch more than 60% bycatch, which is discarded.

Lost fisher nets

Lost fisher nets develop into ghost nets, which catch and kill wildlife and continue fishing after the carcasses decayed.

Marine aquaculture

Marine aquaculture is a reasonable solution to ensure protein delivery from fish and shellfish without reducing wild populations. However, aquacultures need strong regulations to avoid for example habitat damage, spreading of diseases, escapes of farmed fish, or eutrophication.

Useful guide for sustainable seafood

Seafood Watch from the Monterey Bay Aquarium

Greenhouse effect

the trapping of heat (from sunlight) by CO2 and other "greenhouse gases" (e.g. methane and water vapor) in the atmosphere.

Global Warming

The anthropogenic increase of CO2 in the atmosphere caused by, e.g., fossil fuel burning has lead to a significant increase in global temperature, known as "Global Warming". The sum of effects of CO2 increase in the atmosphere is also known as "Climate Change".

Indicators of Global Warming

decrease in glaciers, less snow cover, rise in sea level, increase in ocean heat content, decrease in sea ice.

Increase in Ocean heat content

Consequence of global warming. Water masses between 0-700 m water depth are showing averaged temperature increases up to 0.3 oC per decade. The warming signal is also visible, although weaker, in the deep ocean.

Ocean deoxygenation

the intensification and spreading of oxygen minimum zones. At higher temperatures, water dissolves less oxygen and develops stronger and shallower thermoclines, which decrease ocean ventilation.

is a consequence of global warming

Coral Bleaching events

consequence of Ocean Warming, in combination with El Niño, are coral bleaching events, which can lead to the death of corals.

Global warming effect on food chains

Global/Ocean Warming has lead so far to a 50% reduction of the sea ice in the Arctic Ocean. This has negative consequences on arctic food webs, which depend on sea ice either as food source (sea ice biota) or as floating ground. Polar bears are especially affected as they need sea ice to hunt for their food – the seals.

How does the ocean store CO2?

Through three pumps. the solubility pump, the soft-tissue (organic matter) pump, and the carbonate pump. The uptake of anthropogenic CO2 by the ocean has been documented world wide.

Results of the dissolution of CO2

The dissolution of CO2 from burned fossil fuels leads to a decrease in ocean pH, caused by the formation of carbonic acid, which dissociates and releases protons.

Decrease in ph by the dissolution of CO2

The decrease in pH (release of H+) by the dissolution of CO2 leads in some areas of the ocean to the dissolution of calcium carbonate: H+ (proton) combines with CO32- (carbonate) to form HCO3- (bicarbonate). This is a problem for all calcifying organisms such as stony corals, sea urchins, pteropods, coccolitophores.

What happens if CO2 partial pressure increases to 700ppm

Major parts of the global corral reefs will die

Who has shown sensitive responses to the decrease in ph?

Pteropods (planktonic snails with CaCO3 snail house) and Coccolithophores (algae with CaCO3 shells) have shown a sensitive response to pH decrease in experiments. Pteropods are an important food source for young stages of salmon. Coccolithophores are at the base of many food webs. The loss of both organisms could have dramatic effects on food webs.

Human made plastic waste4

is accumulating in our oceans creating a threat to many animals who get entangled (strangulated) or die after plastic ingestion (starving to death).

Pacific Garbage Patch

Due to ocean currents, major amounts of plastic are accumulating in subtropical gyres, particular in the North Pacific, called the "Pacific Garbage Patch".

Plastic Products

Have a long time life (up to several hundred years) in the ocean

Microplastic

Aside from large plastic waste, we are polluting our oceans with microplastic. These small plastic pieces are coming from, e.g., abrasives in tooth brush or skin peeling, washing of

plastic clothes, or the break up of large plastic pieces.

Effects of micro plastic

currently unknown. One potential

negative effect could be the tendency to accumulate chemical pollutants, which can then be released if microplastics are ingested by animals. Microplastic have also been found accumulating in the biomass of commercial fish and seafood, meaning we are probably ingesting them as well.

My little plastic footprint

App helps to keep track of your plastic footprint and how to reduce plastic usage.