Marine Ecology Midterm Exam

Ecology

The study of ecosystems, or the study of how living organisms interact with each other and their environment

Ecosystem

An interacting community of living organisms and the non-living environment around them

Individual

One member of a species

Population

All of the members of a species within an area

Community

All of the different species in the area

Example of four abiotic features within an ecosystem

Temperature, Nutrients, Salinity, Light

Primary Producers

Autotrophs, or organisms which can photosynthesize

Primary Consumers

Feed on the primary producers. Usually herbivores

Secondary Consumers

Feed on primary consumers. Usually carnivores

Tertiary Consumers

Feed on secondary consumers. Usually carnivores

Niche

The combined set of biotic and abiotic factors which a species requires in order to survive, grow, and reproduce

Niche Partitioning

High biodiversity often persists because multiple species utilize slightly different subsets of a resource

What happens when two species have an overlapping niche?

They require the same resources. Creates competition

Intraspecific Competition

Within a species

Interspecific Competition

Between different species

Foundation Species

Determine the diversity of other taxa through non-trophic interactions, most dominant in numbers or size, and regulate the energy flow in its ecosystem

Examples of keystone species

Sea otters in kelp forests

Examples of foundation species

Kelps, Corals, Mangroves, Oysters

Keystone Species

Have an outsized impact on the rest of the community through their trophic interactions(feeding). Never most abundant.

Trophic Cascade

When a change in one trophic level has a chain reaction effect on other trophic levels down the food web

Top-Down Effects

When a higher trophic level organism controls or shapes the ecosystem

Bottom-Up Effects

When a change in a lower trophic level organism has an impact on other upper level species

On average how much energy is passed from one trophic level to the next?

~10%

Differences between a keystone species and a foundational species?

Foundation species are normally dominant and structure the ecosystem through non-trophic interactions. Keystone species are normally rarer and structure the ecosystem through trophic interactions.

The Earth’s 4 major ocean basins

Arctic, Atlantic, Pacific, Indian

Neritic Zone

From the shore to the edge of the continental shelf(coastal)

Oceanic Zone

Anywhere past the continental shelf

Why are coastal zones often more productive than the open ocean?

They have higher species diversity and a greater abundance

Benthic

Anything attached to the seafloor

Pelagic

Anything in the water column

Photic Zone

Where light reaches

Aphotic Zone

Where light no longer reaches

Thermocline

A distinct change in temperature vs. depth, as one mass of water sits on top of another

Biome

A large region of similar characteristic climate and oceanographic conditions

Biodiversity

A measure of the number of different organisms in an ecosystem or area

Alpha Diversity

Single point or location

Beta Diversity

Habitat

Gamma Diversity

Regional

Ways to quantify biodiversity

Species richness, Species evenness

Functional Diversity

How many different functional roles are being fulfilled in an ecosystem

What forms the physical structural and trophic base of most marine ecosystems?

Marine algae and plants

What do plants and algae need in order to grow?

Light, Nutrients, Space, Carbon Dioxide, and Water

Light

Electromagnetic energy that exists across a broad spectrum of wavelengths

Chlorophyll-a

The primary light-capturing molecule found in almost all photosynthetic organisms

At what wavelenghts does chlorophyll-a absorb light?

480nm(blue light) and 660nm(red light)

Problem with light and depth

Light attenuates with depth

Solution to problem with light and depth

Move towards the light source or broaden your light-absorbing abilities

Accessory Pigments

Expand the wavelengths of light the organism is capable of utilizing

Photosynthesis

The process by which organisms capture light energy and trap it in organic molecules

6CO₂+6H₂O+light→C₆H₁₂O₆+6O₂

Aerobic Respiration

The breakdown of sugar molecules using oxygen to produce energy

C₆H₁₂O₆+6O₂→6CO₂+6H₂O+energy

Primary Production

The formation of organic matter through the trapping of light energy and the assimilation of inorganic nutrients.

How do we measure primary production?

By measuring the production of oxygen over time, and use it at a proxy for photosynthesis

Gross Primary Production(GPP)

The total amount of carbon that is fixed by autotrophs.

Net Primary Production(NPP)

The total amount of carbon that is fixed by autotrophs minus the amount of carbon lost to respiration

NPP=

GPP-R

Light and Dark Bottle experiments are used to?

Estimate primary production in sea water

What is occurring in the light bottle?

Photosynthesis and Respiration(proxy for NPP)

What is occurring in the dark bottle?

Only respiration

GPP=

NPP+R

Irradiance

Intensity of light

What effect does too little light have on photosynthetic activity/efficiency?

Nothing happens

What effect does too much light have on photosynthetic activity/efficiency?

The cellular components become damaged

Which ocean ecosystem is most productive?

The open ocean

What carries out the majority of primary production in the open ocean?

Phytoplankton

Plankton

Any organism that cannot swim against a current

Nekton

Any organism that can swim against a current

Phytoplankton

Any organism that is planktonic and photosynthetic

Zooplankton

Any organism that is planktonic and heterotrophic

Major Phytoplankton Groups

Bacteria, Diatoms, Dinoflagellates, and Coccolithophores

What are the 4 factors governing primary production in the open ocean?

1. Light

2. Nutrients

3. Stability

4. Mixing

How does light govern the open ocean?

Light attenuates with depth

Changes seasonally depending on latitude

How does nutrients govern the open ocean?

They are used up quickly at the top of the water column, but are often abundant at deeper depths

How does stability govern the open ocean?

It is time spent at the surface for algae to grow

How does mixing govern the open ocean?

To replenish nutrients from the depths up to the surface

To keep phytoplankton in the surface waters

Compensation Depth

The depth at which gross photosynthetic carbon assimilation equals carbon losses from respiration

Critical Depth

The depth where the integrated daily photosynthetic carbon assimilation equals by the integrated daily carbon losses from respiration

Phytoplankton growth occurs when?

The mixed layer depth is shallower than the critical depth

Tropical, Polar, or Temperate?

Tropical

Tropical, Polar, or Temperate?

Polar

Tropical, Polar, or Temperate?

Temperate

What are the light, nutrient, and mixing productivity conditions in tropical climates?

Light- High and constant year-round

Nutrients- Low availability

Mixing- Shallow

What are the light, nutrient, and mixing productivity conditions in polar climates?

Light- High in summer, but low rest of year

Nutrients- High availability

Mixing- Deep

What are the light, nutrient, and mixing productivity conditions in temperate climates?

Light- High in summer, medium in fall+spring, low in winter

Nutrients- Available in winter, low in summer

Mixing- In summer, thermocline establishes and mixing is shallow. In winter, thermocline disappears and mixing is deeper.

Secondary Production

The growth and accumulation of biomass by heterotrophic organisms

How is secondary production measured?

As the change in biomass over time

The two groups of organic matter

POM and DOM

POM

Particulate Organic Matter

DOM

Dissolved Organic Matter

Define sloppy feeding

When animals feed they often drop some of the food which falls into the water column and sinks(DOM)

Marine Snow

Anything that sinks out of the photic zone down to the ocean floor

Why are food chains energetically inefficient?

Energy losses at each trophic level

What can convert DOM into POM?

Microbes

Microbial Loop

The pathway connecting microbes to larger food webs via DOM

What is the Production:Biomass P/B ratio used to compare?

Production across different groups or organisms

Cohort

A group of individuals all born at the same time

What does high primary production correlate with?

High secondary production

Biogeography

The study of where living things are distributed in space

What is this model?

BAM (Biotic, Abiotic, Movement)

Biotic