GEOL 160 Midterm 3

Nutrients

inorganic compounds that are used by bacteria and plants to build organic material

Examples of nutrients

inorganic carbon
phosphate
nitrogen, mainly ammonia or nitrate (NO3)
silicon as silicic acid
essential metals

How do nutrients become part of organic compounds?

autotrophs (plants) create them
heterotrophs alter them

What is fundamental to nutrients?

Nutrients are matter as opposed to energy. This means that they can be used and reused.

biogeochemical cycling

movement of nutrients through the earth as they are used and reused

Nutrient cycles

1. start with introduction of nutrients into the 2. environment from the atmosphere and rivers
moved to where organisms will use them in the ocean
3. incorporation into organisms such as plants and bacteria through absorption
4. other organisms ingesting them or bacteria breaking them down so they can be used again

Where are nutrients rare and why?

The ocean surface
They are used as fast as they become available
Nutrient content is low in the surface ocean due to phytoplankton uptake and particle settling

Nutrients in the deep ocean

come from organisms that die and sink to the bottom of the ocean making incorporating their nutrients into deep water circulation and recycled (with upwelling) and used again

Ocean nutrient cycles in the photic and aphotic zone

photic zone: uptake by phytoplankton
particles settle
aphotic zone: phytoplankton remains decompose, releasing nitrate

Gases in the ocean

partially recycled

Oxygen in the ocean

Oxygen is used and not replaced except by deep water formation. Wherever oxygen is not in the water column, most organisms can't live.

Limiting nutrient

that nutrient that is least abundant in proportion to demand

oxidize

combine or become combined chemically with oxygen.

reduce

gain of electrons

blooms

A relatively rapid increase in the population of (usually) phytoplankton algae in an aquatic system. Algal blooms may occur in freshwater or marine environments.

Blooms at mid to high latitudes

marked seasonality with nutrient supply
During winter, low sunlight levels limit biological productivity- nutrient level increases due to upwelling (lowest bloom season)
During spring, high sunlight and nutrient levels lead to high productivity (peak bloom season)

Chlorophyll

can be used to assess ocean productivity by reflecting upwelling patterns

Photosynthesis

6CO2 + 6H2O + energy --> C6H12O6 + 6O2

Respiration

C6H12O6 + 6O2 ---> 6CO2 + 6H2O + energy

Phylogenetic classification

a means of naming all organisms and grouping organisms by degree of similarity
developed by Linnaeus

Kingdoms

large scale groupings

Classification sequence

Kingdom, Phylum, Class, Order, Family, Genus, Species

Metaphyta

kingdom that includes multicellular plants

Metazoa

kingdoms that includes multicellular animals

Fungi

kingdom that includes multicellular plant-like organisms, no photosynthesis

Protista

kingdom that include single-celled organisms with a distinct nucleus

Monera

single celled organisms without a nucleus

environment

A combination of physical, chemical, and biological factors that describe a living space

physical factors

temperature, salinity, light, water depth, substrate

chemical factors

nutrients, gases

biological factors

trophic states, food chains or webs

littoral

intertidal zone

neritic

subtidal shelf

pelagic

open ocean beyond neritic zone

euphotic

uppermost sun-lit zone

photic

any zone that has some light

aphotic

no light

littoral (water depth)

wave zone

sublittoral

below wave zone to 200 m

bathyl

200-2000 m

abyssal

>2000 m

hadal

deepest waters within trenches (>6-8000 m)

biosphere

global assemblage of many different ecosystems and include all life on Earth

ecosystem

a community of organisms and their physico-chemical environment

community

assemblage of organism populations that live together

population

all individuals of a single species

biological diversity

is a measure of the species richness (variety) in a given population (ecosystem)

high biodiversity helps...

ecosystem stability

biological communities are composed of:

autotrophs (producers)
heterotrophs (consumers)

Productivity

the amount of biomass that organisms yield to the food web
that is biomass not used by organisms for internal respiration

primary productivity is the...

biomass associated with autotrophs

secondary productivity is the...

biomass associated with heterotrophs

herbivores

eat plants

carnivores

eat other animals

scavengers

eat large organic detritus, carrion

decomposers

eat small organic detritus (ex: bacteria, fungi)

omnivores

do two or more of the above

Filter feeders

sweep through water column (or let water sweep by them) and capture any organism in their path that is not too large

Browsers

scrape food off surfaces or feed on plant or sessile benthic organisms

deposit feeders

eat sediment and extract organic material or small organisms from the sediment

Predators/scavengers

actively pursue other living or dead organisms,

chemosynthesis

H2S or H2 + CO2 --> organic matter + sulfate methane
autotrophs will absorb a variety of unnecessary organic chemicals and trace elements which are added to the plant biomass. In most cases, these materials will be biological neutral to the host organism. Eventually, as the organic materials are transferred through the food chain, their concentration will be high enough to become hazardous to organism health

food web

A community of organisms where there are several interrelated food chains
more realistic way to view predation in a biological community

food chain

sequence of heterotrophs and autotrophs that feed on each other in sequence

trophic level

Each level in the feeding sequence

lowest trophic level

autotrophs

higher trophic levels

heterotrophs

food pyramid

shows the pattern of mass transfer as one cycles through a food chain

what is the form of checks and balances that allow for communities to survive?

population variation: birthrate, recruitment, and death rate
environmental resistance: defines the combination of biotic and abiotic factors that limit a species population
ecological succession: shows the natural (and sometimes) unnatural evolution of ecosystems

biological succession

- Biological communities do not spring into existence full-blown but develop gradually
- Stable communities can be subject to cyclic environmental forcing like high-low tides, spring-neap tides, seasonality, ENSO, and climate changes
- communities may reach a new equilibrium if external forcing causes major disruption (not cyclic). This is termed succession.

aspects of succession

•Forest communities change in response to long-term climate change.
•Forest communities change in response to short-term burning.
•Pioneer communities are the first organisms to colonize (or recolonize) an area.
•Climax communities are the final stable communities that will prevail until some external forcing changes the community structure.

open ocean systems "boundaries"

have no effective boundaries, except the ocean surface. In principle, open ocean ecosystems go all the way to the ocean bottom.

planktonic

organisms in the open ocean, move with currents

nektonic

real swimmers

benthonic

living at or near the ocean bottom

phytoplankton

autotrophs

zooplankton

heterotrophs

What type of organism dominates the ocean dominates the surface ocean?

consumers that are herbivores

What type of organisms dominates the intermediate water depths?

carnivores

What type of organism dominates the deep ocean?

omnivores

How do phytoplankton avoid getting eaten?

their small size (hard to see) or by their translucent color (hard to see)

how do zooplankton avoid getting eaten?

Schooling (harder for bigger predators to get at them) or Vertical migration (stay in aphotic zone during the day and rise to ocean surface to feed at night)

types of zooplankton

-Foraminifera (carbonate shells)
-Radiolarians (siliceous shells)
- Copepods and Krill (Arthropoda)

types of phytoplankton

-Cyanobacteria (blue-green algae)
-Diatoms (siliceous shells)
-Silicoflagellates (siliceous shells)
-Coccolithophores (carbonate shells)

Key factors in phytoplankton growth

-Nutrients
-Light
-Temperature
-Means of staying afloat in photic zone

benthos

-Epifaunal - crabs, star fish, sea urchins
-Infaunal - worms, molluscs
-Sessile benthic - sea fans, sea anemones

epifaunal

benthic organism
living on top of the ocean bottom and moving around
crabs, starfish, sea urchins

infaunal

benthic organism
living mostly in the bottom sediment and moving around
worms, molluscs
•Detritus feeders - move through sediment and remover organic material from it
•Filer feeders - live in sediment for protection, but suck water from surface ocean for filter feeding.
•All are mobile in response to sedimentation

sessile benthic

benthic organism
living fixed on the ocean floor
filter feeders- depend on sea ocean circulation
sea fans, sea anemones

nekton

•Swimming ability: need streamlined cross-section for minimal drag
•Buoyancy: need specialized adaptations to help keep afloat (air sacs, liquid fats)
Search for prey: most food searches occur at night or in aphotic zone; need sonar or keen eyesight to find prey

types of nekton

•Types of nekton (free swimmers)
-Fish: either bony fish (most common) or cartilaginous fish (sharks, rays)
-Sea mammals: whales, seals, porpoises, dolphins
•Birds
•Reptiles: sea snakes, turtles, sea crocodiles
•Squid

Bioturbation

the disturbance of sedimentary deposits by living organisms

deep ocean systems controlling factors:

cold water 1-5 degrees Celsius
aphotic
very high pressure (200-200 times P at sea level)
muddy bottoms
regionally strong currents
low biomass
most organisms are detritus or bottom feeders

characteristics of unusual deep ocean systems

Degree of anoxia controls number and type of benthic organisms.
In truly anoxic conditions (chemosynthetic) bacterial mats grow - little else.
In some places special sources of nutrients occur (Hydrothermal vents, Cold (Oil, natural gas) seeps, Whale carcasses).

coastal marine ecosystems

•Ecosystems occurring in shallow ocean bottom conditions (edges of islands, continental shelf)

Substrate

aka ocean bottom conditions are important
rocky, sandy, muddy bottom

Ecosystems are sensitive to...

substrate, wave activity, atmosphere temperature, nutrient supply, amount of sunlight

Types of coastal marine ecosystems

•rocky shoreline, sandy shoreline, muddy shoreline, coral reef , kelp forest, mangrove swamp

Rocky shore ecosystem

•Typical of high relief coastlines
•Biological zones are defined on the basis ofdegree of exposure during daily tidal cycle
•Key factors in growth:
-Avoid drying out
-Avoid overheating
-Avoid getting broken up by wave action
Periwinkle zone
below is the barnacle zone
below is the predatory snail zone

Tide pools

contain animals that require more protection from wave action; sea anemones, fish, crabs