OCS 1005 Exam 3 LSU Sutor

What is a eustatic change in sea level? What are the causes of such a change?

These are longterm, widespread changes in sea level caused by the amount of water in the oceans changing, changes in sizes of ocean basins, expansion and contraction of seawater due to changes in temperature

What characterizes an erosional coast? What is an example?

Erosional coasts have lots of wave action and are dominated by rock. Examples are Maine, British Columbia, Southern tips of South America and Africa

What wave behavior concentrates wave energy at a headland? How will this shape the shoreline over time?

Refraction concentrates wave energy at headlands. This will create a smooth shoreline over time

Coast

The boundary between the ocean and the land

What are some of the factors that determine the character of a coast?

Whether the coast is on an active or passive margin, the amount of wave energy, and the slope of the land

What characterizes a depositional coast?

Depositional coasts are low energy, they are protected and not subject to frequent, large waves and are dominated by sediments. An example is the coasts in the Gulf of Mexico

What is the general relationship between beach slope and grain size of sediments on a beach?

The steeper slops have larger grains and the flattest parts of a beach have sediments of the smallest grain size

Longshore drift

movement of sediment along the coast by wave action

What are longshore currents?

currents that run along the coast and can transport sediments

What is balanced in a coastal cell?

The input and output of sand on a beach

What is the source of most sediments in the coastal zone?

river input

If the Louisiana coast is a depositional coast, then why is so much coastline disappearing?

Subsidence of the land, rising sea level, and the lack of input of sediments from rivers due to man made diversion structures is causing the erosion of the Louisiana coast

What are barrier islands dependent upon to maintain their size and position?

A constant input of sediment

Describe generally how a hurricane would impact a barrier island

Sediment is eroded on the seaward side of the island and deposited on the landward or bayside of the island

Where are you likely to find a river delta?

In an area with a board continental shelf and low tidal action

What is a river dominated delta? What is an example?

A delta where strong freshwater discharge dominates. The Mississippi River delta

What is a tidally dominated delta? What is an example?

A delta where freshwater discharge is overpowered by tidal currents. The Ganges river system is a tidally dominated delta

Moraines are deposits that build coastlines. How were they deposited and what is an example of coastal features built by moraines?

Moraines were deposited by advancing glaciers and left behind when the glaciers retreated. Cape Cod is an example of a coastal feature built by moraines

What are two main ways human activities affect coasts?

Through activities that decrease sediment delivered to the coast and building coastal structures that alter the erosion and depositional patterns on the coast

How do breakwaters alter the coast?

There is an increase of sediment deposited behind the breakwater due to the decrease in erosional forces because the beach behind the breakwater is protected from wave action

What is a groin and why is it built? How does it affect the coast?

Groins are structures that extend from the beach to the water to counter erosion by trapping sand. Groins change the deposition patterns on a beach by trapping sand on the up current side but having increased erosion of sand on the down current side

Why are seawalls built and how do they affect the coast?

Why is importing sand not a perfect solution to beach erosion?

The sand is generally mined offshore and is finer grain than the beach sand and so erodes more quickly

What is a mixture?

A combination of two or more substances that are not chemically combined

What is a solution?

homogeneous mixture

What is a solvent? Give an example

The substance in a solution that is present in the greatest amount. Water is often a solvent

What is a solute? Give an example

A substance whose particles are dissolved in a solution and example is cool aid

What are the two most abundant ions in seawater?

sodium chloride

What is salinity? What is an average value of salinity in percentage and psu?

What is the main source of dissolved constituents in the ocean?

issolved crustal rock, delivered to the oceans by rivers as part of the water cycle

What is the source of sodium and chloride in the ocean?

Volcanic

What is Forchhammer's Principle?

The ratio of the major salts in seawater is constant, even if the total concentration changes

Why are we able to calculate total salinity by only measuring the concentration of chloride ions?

Because the ratio of chloride to the other ions is constant (Forchammer's principal) so if we measure the concentration of one, we can calculate the total concentration

How does salinity affect the heat capacity and freezing point of water?

They both decrease with increasing salinity

What is residence time?

he average length of time an atom of a particular element stays in the ocean

How are dissolved constituents removed from the ocean?

They are bound to sediments and returned to the mantle at subduction zones where they are recycled

What is the mixing time of the ocean? What is true of any element whose residence time is greater than the ocean mixing time?

The mixing time is 1600 year. Any element whose residence time exceeds 1600 years will be evenly distributed throughout the oceans

What is a nonconservative constituent? What is an example?

A constituent that is tied to a biological or seasonal cycle (oxygen, carbon dioxide, calcium)

If Nitrogen is is present in the atmosphere at a concentration of 78%, why is it present in seawater at only 48%?

Gases dissolve in seawater based on their solubility. Nitrogen is not as soluble in seawater as oxygen or carbon dioxide

How does temperature affect the solubility of gases in seawater?

Solubility increases as temperature decreases. Colder water dissolves gases more readily

Why can water hold more carbon dioxide than other gases?

Carbon dioxide combines with water when it dissolves to form carbonic acid so the concentration of carbon dioxide in seawater is being constantly depleted and more carbon dioxide is free to dissolve

Where is most of Earth's surface carbon stored? How does it get there?

Most of the carbon is stored in ocean sediments. carbonic acid combines with calcium, producing calcium carbonate. Animals use this to build shells and when the animals die, the shells sink to the bottom sediments.

How does the concentration of oxygen and carbon dioxide change in the first 1000m of the water column?

How does the concentration of oxygen and carbon dioxide change in the first 1000m of the water column?

What is the average pH of the ocean? Is the ocean acidic or basic?

8, basic

Briefly describe the oceans buffering capacity to changes in pH

If the pH of the ocean changes, the rate of the chemical reactions that create carbonate, bicarbonate, and carbonic acid will adjust to maintain equilibrium

What is the Calcium Carbonate Compensation Depth? (CCD)

The depth at which calcium carbonate accumulation equals it's dissolution

highest primary productivity, lowest primary productivity

coral reefs and kelp, open ocean

energy transferred to higher trophic level

energy is reduced by a factor of 10 for each trophic transfer

biogeochemical cycle

process in which elements, chemical compounds, and other forms of matter are passed from one organism to another and from one part of the biosphere to another

largest biogeochemical cycle and the basic steps

carbon cycle, co2 in the atomosphere is dissolved in the ocean and taken up by phytoplankton through photosynthesis, carbon is transfered through the food web, can also be transferred to sediments by burial of shells and become limestone or return to the atomosphere, carbon can be returned to the atmosphere via respiration of marine organisms or land processes adn the cycle can start over

fixing nitrogen

binding it to oxygen or hydrogen so its available for life

nitrogen cycle

nitrogen enters the ocean through runoff or from the atmosphere, is brought to the surface by upwelling, bacteria fix it and producers use it to build organic matter and pass through other trophic levels

three other important elements

phosphorus cell building, silica shell building, iron photosynthesis and fixation

limiting factor

An environmental factor that prevents a population from increasing

euphotic zone

the upper layers where photosynthesis is largely confined because sunlight can penetrate

light penetration in open ocean vs coast

600 open 100 coast

temperature affect on organisms

metabolic rates

salinity of sea water greater than internal salinity of cell

water will move out of the cell

neritic zone, pelagic zone

coast to continental shelf, continental shelf throughout open ocean

vertical zonation of pelagic zone

light and increasing depth

vertical zone of pelagic area containing the euphotic zone

euphotic defined based on light, epipelagic and euphotic are often the same

convergent evolution

animals non-related with similar lifestyles developing similar traits, streamline fish

phytoplankton

single celled, use photosynthesis

zooplankton

single/multi celled, consume other organisms

plankton

plants and animals that cannot swim strongly against a horizontal current, classified by size

microbial loop

recycling of carbon between bacteria, flagellates, viruses, and a dissolved pool of organic matter

coccolithophores

autotrophic, surface, calcium shells

autotroph

makes its food, mixotrophs can make and take

dinoflagellates

auto or mixo, have flagella, highly motile, toxins, algal blooms

diatoms

autotrophs, silica shells, dominate high nutrient upwelling zones

compensation depth

rate of respiration=photosynthesis

holoplankton vs meroplankton

holo are plankton forever

microzooplankton

Single celled heterotrophs comprising of flagellates and ciliates

foraminiferans

amoebas, calcium shells

copepods

abundant, multicelled, fast, migration

diel vertical migration

dvm, stay at depth during day and migrate to surface at night to feed

euphausiids or krill

prey for whales, mix ocean water

meroplankton

larval fish, crabs, shellfish

invertebres

soft bodied animals without rigid internals

supported rise of animals

the evolution of microbes into oxygen producing cyanobacteria

simplest multicellular animals

sponges, phylum porifera, no tissues, sessile, suspension feeders

cnidaria

one step from simplest, have specialized tissues allowing coordinated swimming, feeding, and responding to stimuli; sea anemones, jellyfish, corals, siphonophores

how do cnidarians eat

nematocysts

body forms of cnidarians

polyp(anthozoa class anemones and corals) and medusa

hydrozoa

siphonophores are colonial hydrozoa, the portuguese man of war is the most familiar of them containing stong toxins

ctenophora

eight rows of cilia for moving, sticky cells to capture prey called colloblasts instead of nematocysts like cnidaria

tubellaria phylum platyhelminthes

have organs, systems, cns and brain area allowing coordinated movements of muscular system

nemoatoda

highly abundant worms, small in size, living in soft sediments

nermertea

have a complete gut, mouth, anus, and circulatory system unlike platyhelminthes such as tubellarians and nematodes

coelomates

have a digestive tract seperated from body wall

annedlida class polychaeta

feed by ingesting organic rich sediments, other animals, or tenticles

mollusca

polyplacophora, gastropods:snails, bolivia: clams, muscles, scallops, Cephalopoda: octopuses, cuttlefish, squids, nautilus

cephalopods are mobile and visual because

they have complex nervous systems, reduced shells, siphon for locomotion, and large eyes

arthropoda

exoskeleton made of chiton and jointed appendages

arthropods grow by

shedding their exoskeleton and creating larger ones called molting, sudden increases in size occur once they finish molting

largest group of marine anthropods

crustacea, the largest of the crustaceans are decapods including crabs and lobsters

prehistoric group of anthropods living today

horseshoe crabs, providing millions of eggs for migrating birds to eat

echinoderms

advanced invertebres, different from others because they share radial symmetry in their adult age with cnidarians

types of echinoderms

sea stars, brittle stars, sea urchins, sea cucumbers, feather stars

most advanced animal phylums

chordates having notocord, tubular dorsal nervous system, gill slits