Introduction to Marine Ecology and Conservation Quiz 1

What is marine?

Having to do with the ocean

What is ecology?

The study of the relationships of organisms with each other and with their physical environment

What is conservation?

The act of protecting Earth's natural resources for current and future generations

How do the spatial dimensions of life on land compare to those in the ocean?

Terrestrial: thin veneer of life along surface

Ocean: life distributed across large depth range

• Surface area: Oceans cover ~70% of Earth, land ~30%.

• Depth of life:

  • Land: life is mostly limited to soils, plants, and low-flying organisms → ~36 m average.

  • Ocean: average depth of ~3,600 m where life is found.

• Comparison: The ocean is ~100x deeper for life than land.

• Overall space for life: When depth is combined with surface area, the ocean provides ~200 times more space for life than land.

How is light distributed across Earth, and why does it vary?

• Light is unevenly distributed and shifts with the seasons due to Earth’s tilt.

• Poles: strongest seasonal effect → up to 24 hours of daylight in summer and 0 hours in winter.

• Equator: light is consistent → ~12 hours of daylight year-round.

• Angle of sunlight: most direct at the equator → light is more intense compared to higher latitudes.

What happens to sunlight when it enters the ocean?

• Sunlight is made of many colors (visible in a prism).

• Once it hits the ocean, light is reflected or absorbed.

• Water acts as a filter:

  • Red light is absorbed first (shallowest).

  • Blue light penetrates the deepest.

If you were to dive deep into the ocean, what colors would you see?

Blue, bc it travels farthest 

What type of radiation is visible light?

• electromagnetic radiation, classified by wavelength.

Are most types of light visible to humans?

• No. Most electromagnetic radiation is not visible to us, such as:

  • Ultraviolet (UV)

  • Infrared (IR)

Why is visible light important in the ocean?

• best wavelengths for penetrating water.

• In contrast, UV and IR do not penetrate water well—water is essentially opaque to them (like black coffee is to visible light).

Explain how Depth and Light work in the ocean.

Because light gradually gets absorbed or scattered by ocean water, it gets darker as you travel deeper

What are the ocean light zones by depth?

• Photic zone (with sunlight)

  • Euphotic: enough light for photosynthesis

  • Dysphotic: dim light, not enough for photosynthesis

• Aphotic zone: no sunlight

What is important to know about the relationship between ligh in the ocean?

Some colors of light penetrate deeper into the ocean

How might the depth distribution of light in the ocean affect life?

• Photosynthesis near surface

• Life concentrated in shallows

• Color of organisms can change with depth

• Ecosystems in dim light or dark may depend on food from above

• Bioluminescence in the deep ocean

Why is the Ocean blue?

• Some light that

  enters the ocean is

  scattered and

  bounces back to the

  surface, creating its

  color

  • Most of the light that

  bounces back is blue,

  because the other

  colors have been

  absorbed

Water Motion: What is the difference between standing waist deep in a 10mph stream vs. standing in a field with 10 mph wind on a sunny day? 

Force pushing you

• Related to density of water

(water has a greater

density)

• Same speed has a very

different effect

How might water motion and density affect biology?

• Moving life that drifts in the

flow

• Life concentrates where

nutrients and food are

delivered

• Some organisms anchored to

the bottom

• Some organisms have evolved

of hydrodynamic shapes

• Water flow affects local

temperature

What are the primary causes of water motion?

• Wind

  • Tides

  • Density differences

  • Earth’s rotation

What are ocean gyres and why are they important?

• large circular surface currents in the ocean

• Driven by global wind patterns + Earth’s rotation (Coriolis effect)

• Found in each major ocean basin

• Important for:

  • Transporting heat, nutrients, and organisms

  • Concentrating debris (e.g., Great Pacific Garbage Patch)

Upwelling

the delivery of deep water to

the surface, which is often

• Colder

• Nutrient rich

How do Tides effect the motion of water?

Gravitational pull of

moon and sun

• Larger tides when

they’re lined up

• Smaller tides when

out of alignment

How might tides affect life?

• Exposure to air at low tide

• Drive some coastal currents

How are wave formed?

• by surface winds

• Friction between wind and ocean surface creates ripples, which grow to waves

What are wind waves?

small, irregular waves that are made locally by wind

What does Swell mean.

Is waves that started as wind

waves, but travel beyond the

source of the wind

• Usually regular and smooth

• Can occur when it’s not windy

• Can travel across ocean basins

Why are Waves important for ecologically?

• Mix nutrients and other materials vertically

• Move materials laterally near shore, as they break

• Structure ecosystems by differentially removing fragile organisms

When do waves break?

When they reach shallow water 

Which "waves” are not cause by wind?

• Tsunamis: which are caused by land motion underwater – bathtub effect

• Tidal waves: formed by tidal currents

What might deeper water be colder?

Liquid can become stratified, with stable layers with different densities and other properties

• Examples

• Thermocline: warm water

floats on cold water

• Halocline: Less salty water

floats on saltier water

What does Stratification do?

• Can trap some water well below the surface, with upper layers capping those below

• Organic matter can sink to deep water where it decomposes, trapping nutrients

What kind of waves mix deeper?

Big waves

What does the depth of mixing depend partly on?

• Stratification 

Weak stratification allows deeper

mixing

How does latitude affect ocean mixing, and why is this important for nutrients?

• Warm regions: strong thermocline → mixing is relatively shallow

• Cold regions: weaker thermocline → mixing is deeper

• Importance: deeper mixing brings nutrients to the surface, supporting primary production

What drives Global Surface Currents? 

Coriolis force drives currents

• Clockwise in north

• Counterclockwise in south

Create circular patterns called

gyres

Details change a smaller scales

due to factors such as

• Bottom topography

• Land

• Other currents

• Local winds

What is driven by the Coriolis effect?

• Ekman Transport

• Northern hemisphere example:

  • Water moves with wind a surface

  • Friction between water layers pulls

  deeper water along

  • Water curves to the right with depth

  • Net water movement 90 degrees to

  right of wind

Explain how Coastal upwelling happens?

• Along-shore winds create

surface currents

• If going the right direction,

along-shore surface currents

transport water offshore

• What replaces the water

that moves offshore?

• Hole/negative space near

shore

• Deep water is pulled to

the surface to fill the hole

Coastal Upwelling Zones

Concentrated on

west coasts

- Equator-ward

winds cause

offshore transport

- Cool, nutrient rich

upwelled water

Results in:

• Cool air / fog

• High nutrient

concentrations

What are other causes of upwelling?

• Currents interacting with

topography, for example,

hitting oceanic islands

• Surface mixing from

waves and tides

• Equatorial upwelling

• Similar mechanism to

coastal upwelling

• But happens in two

directions with equator

acting like ‘shore’

• Thermohaline circulation

What is Thermohaline Circulation?

Driven by changes in

density

• Temperature

(thermo)

• Salinity (haline)

As salty water cools in

the North Atlantic, it

sinks

Pushes deep water out

of its way, driving a slow

global current

How does the Thermohaline Circulation work?

• Gulf stream brings warm surface

  water to North Atlantic

  • Water cools in cold wind/air

  • Eventually, ice forms

  • Brine rejection: ice formation rejects

  salt, leaving remaining water saltier

• Surface water is more dense: colder

  and saltier

  • It sinks

  • Pushes other deep water, driving a

  slow global current

Why is the Thermohaline Circulation considered the World’s largest current?

• Connects all major ocean basins

• Deep water accumulates nutrients as surface material sinks

• Redistributes nutrients and heat globally

What’s the most important chemical reaction in biology?

My opinion: photosynthesis

Simplified photosynthesis equation:

• Energy (sunlight) + CO2 + H2O ↔ Carbohydrate + O2

What does this equation mean: • Energy (sunlight) + CO2 + H2O ↔ Carbohydrate + O2

Equation goes both ways:

• Going right is photosynthesis:

creation of carbohydrates

• Going left is respiration:

breakdown of carbohydrates

What is a Primary Production (Autotrophy)?

• creation of organic matter from inorganic carbon (CO₂) using energy

• Autotrophs = organisms that produce their own food

  • Examples: phytoplankton, algae, seagrasses

• Importance:

  • Base of the marine food web

  • Supports all higher trophic levels

  • Drives carbon cycling in the ocean

What are Primary Producers (Autotrophs)?

are organisms that can do things like Photosynthesis.

Are there any other forms of Primary Production besides photosynthesis?

• Chemosynthesis

• Main differences is that the energy source is chemical rather than light

• Examples include hydrogen gas or hydrogen sulfide

Chemosynthesis in Hydrothermal Vents

Hydrothermal vents are deep

ocean fissures where superheated

water, with chemicals like

hydrogen sulfide, enters the ocean

Some kinds of microbes can use

inorganic chemicals (e.g.,

hydrogen sulfide) in the hot water

to fuel primary production

without sunlight

A diverse ecosystem can be

formed based on chemosynthesis

Explain what Eukaryotes are?

• Have cells with a nucleus

• Familiar plants, animals, fungi

• Protists: everything else

• Grab bag of different groups including algae and protozoa

What are Prokaryotes?

• No nucleus

  • DNA is circular

  • All single cellular

  • Smaller than eukaryotes

What is Bacteria?

Some autotrophic

What characteristics make a Archaea?

Many live in extreme environments

• Some autotrophic

• Evolutionarily closer to us than

bacteria!

What are the main groups of Primary Producers in the Ocean?

• Plants

  • Algae

  • Prokaryotes (Archaea and

  Bacteria)

Plants in the Ocean?

Plants have vascular tissues like roots and stems

In the ocean, plants are confined to shallow coastal areas

Main groups:

• Mangrove trees:

• Leaves and stems above water

• Roots underwater at high tide

• Seagrasses:

• Resemble grasses on land

• Live in shallow coastal areas

• Can store large amounts of carbon in sediments

• Salt marsh plants, live in estuaries (places where fresh and

saltwater mix)

Plants are locally important in the ocean, but minor players globally

What are Algae?

Relatives of plants that lack roots and

stems

Abundant and diverse in the ocean

What are the two main functional groups that Algae have?

• Macroalgae (AKA seaweed)

  • Multicellular, plant-like algae

  • Includes kelps

  • Mainly anchor to the substrate

  • Plants evolved from green macroalgae

• Microalgae

  • Small, often unicellular, primary producers

  • Can grow in films on the bottom

  • Most float in water

What are Prokaryotes?

• Microscopic single celled organisms

• Archaea and bacteria

• Some are primary producers

What are Phytoplankton?

• The small primary producers that are

adrift in water

• Includes both microalgae and

prokaryotes

• Responsible for most of the primary

production in the ocean

Why are most primary producers in the ocean microscopic, unlike land, which is dominated by larger plants?

Possible answers:

• Surface area to volume ratio: easier to absorb

nutrients from environment when small

• Rapid response to changing conditions: when

nutrients or sunlight arrive, microscopic

organisms can quickly grow their populations

• Bet hedging: by being small and abundant,

chances are better that some of your relatives

will find good conditions

• Little advantage to being big:

• Can’t anchor to hold space for competition

• No need for roots to gather nutrients

• Neutral buoyancy: no need for hard structures to

support growth

What are the important nutrient needed for Photosynthetic Primary Production?

• Nitrogen

• Phosphorous

• Iron

When all needs of primary producers are

met, growth can be extremely fast

What limits primary production?

• Water: Always present

• CO2: Rarely limiting in ocean

• Light:

• Large influence by depth

• Influenced by latitude,

strong seasonal pattern

• Nutrients: frequently the

limiting factor in surface

water

• Used up quickly

• Sink beyond light

• Source needed for high

productivity

What is the purpose of a Trophic Status

To classify Aquatic ecosystems on the basis of how much primary productivity they support

What is the Trophic Status of the level: Oligotrophic?

low nutrient levels and low primary production

What is the Trophic Status of the level: Mesotrophic?

medium nutrient levels and primary production

What is the Trophic Status of the level: Eutrophic

high nutrient levels and high primary production

Give an example of how Primary Production fuels ecosystems?

Arctic example

• Summer

• High light

• High nutrients

• Respiration over winter

• Strong mixing once ice is gone

• Phytoplankton blooms

• Small animals eat phytoplankton

• Fuels growth of larger animals

Bottom line: whales, polar bears and

walruses rely on the nutrients that fuel

phytoplankton growth

This is Secondary Production

Define Heterotrophs?

are organisms that use energy stored by autotrophs to fuel life

Define Secondary production?

the process by which heterotrophs convert organic molecules from primary producers into new life

Describe the Classic Ocean Foodweb? 

Built from the bottom up:

• Primary producers supply food

• Eaten by small grazers

• Eaten by larger predators

• Etc.

• Key concepts

• Herbivore/grazer: eats only

autotrophs

• Carnivore: eats only animals

• Omnivore: eats primary

producers and animals

What are the different Trophic Levels? 

1. Primary Producers

2. Herbivores

3. Intermediate predators /

carnivores

4. Top predators / carnivores

Every time an organism eats another, energy is lost. Why?

• Heat

• Metabolism

• Incomplete digestion

• Reproduction

What is Conversion efficiency?

a measure of how much biomass (the weight of life) is transferred from one trophic level to the next

What’s the trophic level of a carnivore that eats only herbivores?

Level 3: Intermediate predators / carnivores

What’s the tropic level of autotrophs?

Level 1: Primary Producers

What’s the tropic level of an omnivore that eats both autotrophs and herbivores?

Between 2 and 3 

What are the Major groups of heterotrophs?

Entirely heterotrophic groups

• Animals

• Fungi

Some species are heterotrophic

• Protists

• Bacteria

• Archaea

What are Microscopic Heterotrophs in the Ocean?

Protists

• All eukaryotes except plants,

animals, slime molds or fungi

• Diverse grab-bag of species

• Includes autotrophic algae, single

celled amoeba

Bacteria

• Single celled prokaryotes

Archaea

• Single celled prokaryotes

• Evolutionarily distant from

bacteria

Note: some protists, bacteria, and

archaea can be both heterotrophic

and autotropic at the same time

What do microscopic heterotrophs eat?

DOM: Dissolved Organic Matter

• POM: Particulate Organic Matter

Bacteria + Archaea

• So small that they cannot ingest food (too

small to have a mouth)

• Osmotrophs: organisms that consume

dissolved food

• Can also use enzymes to dissolve POM for

digestion

Microzooplankton, like some protist

• Consume POM through ingestion

Micro-organisms in the Ocean?

Standard ocean food chain:

small organism consumed by

progressively large ones

But much of the primary

production doesn’t make its

way directly up the food chain

due to imperfect conversion

efficiency

But, it’s not necessarily lost…

Describe the The Microbial Loop?

Many primary producers die and

leak before being eaten

Some of their biological molecules

dissolve into the water

Heterotrophic archaea and

bacteria, consume these

molecules and grow

Micro zooplankton, comprised of

tiny animals and protists, eat the

archaea and bacteria

Larger animals eat the smaller

ones

This is called the microbial loop

Archaea and bacteria also release

nutrients back into the water,

fueling more primary production

What are the microbes in the microbial loop?

• Defined unicellular animals that

are too small to see without a

microscope

• Includes

• All bacteria and archaea

• Single cellular protists and

fungi

• In this diagram can be

• Primary producers

• Heterotrophic archaea and

bacteria

• Microzooplankton

What is the importance of Micro-organisms in the Ocean?

The microbial loop increases the conversion efficiency of marine food webs: more energy makes it to higher trophic levels Nutrient recycling boosts primary productivity None of this is visible to the eye

What would happen to ocean ecosystems without osmotrophic microbes?

• Osmotrophic microbes (bacteria and archaea) break down dissolved organic matter and recycle nutrients.

• Without them:

  • Organic matter would accumulate, leading to nutrient depletion for other organisms.

  • Primary production would decline due to lack of recycled nutrients.

  • Overall food web efficiency would drop, impacting all levels from plankton to fish.

• Essentially, biogeochemical cycling in the ocean would collapse, destabilizing ecosystems.

Review of Ocean Processes

Physics sets the stage for biology,

driving properties like

• Light availability

• Water motion

• Nutrient distribution

• Water chemistry

Life responds to these

environmental conditions

• All life starts with primary

production

• Secondary consumers feed off

primary producers and other

heterotrophs to build

foodwebs

Whare are the four scales of organization in ecology discussed in lecture?

• Individual: one organism

• Population: a group of

interacting organisms of

the same species

• Community: a group of species that are actively

interacting with each

other at the same time

and place

• Ecosystem: a community

of organisms and the

surrounding physical

environment

Define the scale Individual?

one organism

Define Population?

a group of interacting organisms of the same species

Define Community?

a group of species that are actively interacting with each other at the same time and place

Define Ecosystem?

a community of organisms and the surrounding physical environment

What is a niche?

• Organisms are adapted to live in certain environments

• the set of environmental and biological conditions in which an organism can live

What is an example of a niche?

Crabeater seal example

• Lives only around Antarctica

• Requires access to places to

haul out for resting and giving

birth

• Eats only krill

• Harbor seal example

• Lives northern Pacific and

Atlantic

• Requires access to places to

haul out for resting and giving

birth

• Eats fish, mollusks,

crustacean

In terms of diet, which one has the relatively broader niche? The harbor seal or the crabeater seal?

• Generalists: relatively broad niche (harbor seal)

• Specialists: relatively narrow niche (crabeater seal)

What are some implications of having large changes in body size during development?

• Many ocean organisms undergo extraordinary shifts in body

  size

  • This means that they must shift food with growth

  • Goliath grouper example:

  • Adult eats fish, adult lobsters, even sea turtles!

  • Juvenile: eats tiny plankton

What is a developmental phase that many marine organisms have?

• planktonic larvae

What does Plankton mean?

generally small aquatic organisms that are at the mercy of ocean currents

What does Larvae mean?

early developmental stages of organisms, not yet able to reproduce

why do you think so many marine organisms have planktonic larvae?

• If you live near structure

(reef, coastline, etc.),

there are often many

predators

• Small offspring are not

safe

• It’s better to get them

into open water where

predators are often rarer

• Open water also tends to

have small food items for

small animals

How do you as a larvae avoid being eaten in the open ocean?

• One strategy:

• Be small and clear in a big space

• Like a contact lens in a swimming pool

can you think of any ecological consequences of having planktonic larvae?

• Examples:

• Offspring drift away

• May not live near parents

• Can colonize new places

• High death rate for planktonic larvae that don’t drift to the

right places

• May have high variability in success of offspring

• Good years / bad years due to chance

Define Metamorphosis

Major and rapid transition in bodily form and function

How do Marine organisms perform metamorphosis?

• Settlement: The transition from

plankton to benthic (bottom) habitat

• Settlement involves metamorphosis

• Example: flatfish: sole, flounder,

halibut