Study Guide for Marine Biology

These flashcards encompass key concepts from marine biology lectures regarding ocean chemistry, ocean life, plankton, and marine communities.

Main sources of salts in the ocean

Weathering of continental rocks (rivers) and volcanic gases from hydrothermal vents.

Most abundant ions dissolved in seawater

1. Chloride (Cl⁻) 2. Sodium (Na⁺) 3. Sulfate (SO₄²⁻) 4. Magnesium (Mg²⁺) 5. Calcium (Ca²⁺) 6. Potassium (K⁺) 7. Bicarbonate (HCO₃⁻)

Residence time of an element/ion in the ocean

The average time an element/ion stays dissolved in the ocean before being removed.

Conservative elements/ions in seawater

Examples include Sodium (Na⁺) and Chloride (Cl⁻); their concentrations remain constant.

Non-conservative elements/ions in seawater

Examples include Nitrate (NO₃⁻) and Iron (Fe); their concentrations vary due to biological or chemical processes.

Average pH of modern seawater

About 8.1, which is slightly basic.

Expected seawater pH change by 2100

A drop of about 0.2–0.3 pH units.

Importance of carbonate ions for calcifying organisms

Lower pH means less carbonate ion (CO₃²⁻) available, making it harder for organisms to build calcium carbonate shells.

Difference between autotrophs and heterotrophs

Autotrophs produce their own food; examples are phytoplankton and cyanobacteria. Heterotrophs consume other organisms; examples are zooplankton and fish.

Building block letters in the DNA alphabet

4 letters: A (adenine), T (thymine), C (cytosine), G (guanine).

Major biochemical components in cells

Proteins, lipids (fats), carbohydrates, nucleic acids.

Primary producers in a trophic pyramid (Level 1)

Autotrophs like phytoplankton.

Primary consumers in a trophic pyramid (Level 2)

Herbivores like zooplankton.

Benthic habitats

On or near the seafloor.

Pelagic habitats

Open water column, away from the bottom.

Three domains of life

Bacteria, Archaea, Eukarya.

Main categories of plankton

Phytoplankton (plant-like) and Zooplankton (animal-like).

Examples of algal primary producers

Diatoms and dinoflagellates, which are from the domain Eukarya.

Essential nutrients limiting productivity in the ocean

Nitrogen (N), Phosphorus (P), Iron (Fe).

Typical maximum depth of the euphotic zone

Around 100–200 meters.

Limiting factors for photosynthesis in high latitude regions

Lack of sunlight during long winters.

High productivity regions in the ocean

Upwelling zones (e.g., Peru/California coasts), equatorial Pacific, North Atlantic.

Cambrian Explosion

A rapid diversification of life around 541 million years ago.

Nine different animal phyla by increasing complexity

1. Porifera – sponges 2. Cnidaria – jellyfish, corals 3. Platyhelminthes – flatworms 4. Nematoda – roundworms 5. Annelida – segmented worms 6. Mollusca – snails, clams, squid 7. Arthropoda – crabs, shrimp 8. Echinodermata – sea stars, sea urchins 9. Chordata – fish, mammals.

Difference between ectothermic and endothermic organisms

Ectothermic organisms depend on external environment for body temperature (examples: fish, reptiles), while endothermic organisms maintain constant body temperature internally (examples: marine mammals, seabirds).

Isotonic fluids in marine organisms

The organism's internal salt concentration equals seawater's salinity.

How fish cope with lower salinity than seawater

Fish excrete salt via gills and produce small amounts of concentrated urine.

How birds and reptiles cope with salt

They use salt glands to excrete excess salt.

How mammals cope with salt in seawater

Mammals drink little seawater and excrete salt via kidneys.

Why can rocky intertidal environments host diverse life

They provide stable surfaces, nutrient-rich waters, and tidal mixing that brings oxygen and food.

Why sand and rocky beaches are inhospitable

Shifting substrates, exposure to drying, limited shelter, and instability for attachment.

Factors contributing to decline of the Great Barrier Reef

Coral bleaching, ocean acidification, pollution, overfishing, coastal runoff, crown-of-thorns starfish outbreaks.

Deep scattering layer

A dense layer of migrating organisms found at 300–800 meters deep that reflects sonar.

Communities at mid-ocean ridges

Hydrothermal vent communities with primary producers being chemosynthetic bacteria.

Types of symbiotic relationships

Mutualism (both benefit), Commensalism (one benefits, the other is unaffected), Parasitism (one benefits at the other's expense).