Chesapeake Bay Ecosystem midterm 1

how old is our current chesapeake bay's form?

about 3000 years old

bathymetry

the contours of the estuary

describe the bathymetry of the chesapeake bay coastlines

large and shallow, extensive

which of the following geological forces led to the creation of the chesapeake bay?

bolide meteor, glacial retreat, and the drowning of the susquehana river valley

what geological force led to the creation of our current chesapeake bay's form?

the drowning of the susquehana river valley after the last major glacial melting period

which part of the chesapeake bay is saltier?

the southernmost part of the bay (closest to the ocean)

which part of the chesapeake bay has the lowest salinity?

the northernmost part of the bay (where freshwater flows into the bay from tributaries and land)

estuary

a partially enclosed body of water and its surrounding coastal habitats, where saltwater from the ocean mixes with freshwater from rivers

how deep are the bay's waters relative to the rest of the world?

very shallow (avg. 6m deep)

the chesapeake bay has many tributaries

true

the chesapeake bay is fed by one tributary

false

what is a dentate coastline?

lots of jagged edges and sharp turns

the susquehanna river carved a deep channel into the bottom of the bay

true

during which season does the bay have the freshest water?

spring

during which season is the bay saltiest?

summer

how large is the chesapeake bay watershed relative to others around the world?

it is the third largest estuary in the world

which states/territories are responsible for the chesapeake bay?

delaware, maryland, new york, pennsylvania, west virginia, and washington DC

how mixed is the chesapeake bay estuary?

it is partially mixed (not well mixed) with horizontal and vertical gradients.

how long have people been living in the chesapeake bay region?

over 10,000 years

what were some historically common species in the chesapeake bay?

beavers, sturgeons, whales, oysters, porpoises, blue crabs

sea level rise in the chesapeake bay is about twice the global rate

true

what are primary causes of erosion in the bay?

wave action, storm surge, sea level rise, shoreline composition

what is wave action?

the movement and energy of waves interacting with the shoreline and influencing coastal processes

what are some consequences of sea level rise?

rapid erosion, saltwater intrusion/salinization, more coastal tidal flooding, flooding from storm surges

which of the following are important habitats in the bay?

submerged aquatic vegetation (SAV), oyster reefs, wetlands

before 1600 (colonial times), what were the primary land covers of the chesapeake bay watershed?

forest and wetland

what species historically served an important role in creating/maintaining wetlands across the watershed?

beavers

is the area of agricultural land in the watershed growing and currently at its highest extent in history?

no, it has decreased in recent years to make room for urban and housing development

what are some climate changes in the bay over the last 30 years?

warmer air temps, sea level rise, more frequent/intense storms, warmer waters

what role do living shorelines, breakwaters, and bulkheads play in the rate of erosion in the chesapeake bay region?

they reduce erosion

what is fetch?

the distance wind travels over water before hitting the shore

does longer fetch reduce erosion?

it increases erosion because it results in larger waves that damage the shoreline

since 1950, population and impervious surface cover have increased in the chesapeake bay watershed

true

what is currently the most common land use in the chesapeake bay watershed?

forest/undeveloped land

what do sediment cores from the chesapeake bay region tell us?

there was a higher ratio of benthic to pelagic phytoplankton than we currently observe

define "benthic"

bottom dwelling

define "pelagic"

dwelling in upper sea layers

why is the current ratio of benthic to pelagic phytoplankton concerning?

they show the negative consequences of the bay's eutrophication and subsequent dead zones on aquatic ecosystems

which nutrient tends to be most limiting to phytoplankton near the mouth of the chesapeake bay?

nitrogen

what is the secchi depth test?

a measure of light transmission/water clarity and visibility conducted with a half white, half black disc pushed into the water

a high secchi depth test result indicates murky water

false

what do buffer strips on the edges of agricultural fields do?

they trap agricultural runoff before it hits waterways

what do cover crops do?

they reduce sediment its nutrients to help hold soil in place and absorb its nutrients

what is rotational grazing and its purpose?

moving livestock through a series of pastures to maintain/improve soil, plant, and animal health

what are some methods of reducing stormwater runoff?

rain barrels, rain gardens, green roofs, permeable pavers, planting trees

what do tidal wetlands do?

they protect the shoreline from erosion, nutrient trap, and carbon sink

how do tidal wetlands protect wildlife?

they serve as nurseries and wildlife habitats (ex. for migrating birds)

what is a "rain tax?"

a fee on residents used to manage stormwater by funding stormwater utilities

what are epiphytes?

non-parasitic plants growing on other plants

why do scientists care about epiphytes in the chesapeake bay?

in high quantities, they indicate high nutrient pollution in the water

what are some impacts of eutrophication on seagrasses?

lower growth rate due to reduced light transmission (caused by excessive algae growth), loss of seagrass habitat

what factors lead to larger dead zones in the bay?

more frequent rain, increased impervious surface coverage

how do warmer water temperatures contribute to hypoxic/anoxic dead zones where organisms can't survive?

warm water doesn't hold oxygen well

what is the only major growing source of nutrients entering the bay?

stormwater runoff

what is the largest planned source of reductions between now and 2025?

agricultural runoff

what is the largest current source of nutrients entering the bay?

agricultural runoff

what is the objective of the 1972 clean water act (CWA)?

to make US waters fishable and swimmable again, identify impaired waters

what enforceable plan did the CWA pave the way for?

total maximum daily load (TMDL)

the public can sue the EPA for failure to enforce or implement TMDLs

true (ex. chesapeake bay foundation sued EPA for not taking action to clean Anacostia river)

what is an example of a way to reduce phosphate levels in the bay?

reduced phosphate concentration in laundry detergents

why are oysters beneficial to the bay's health?

they filter sediment and phytoplankton out of the water (up to 50 gallons daily for one oyster)

what factors have contributed to reduced oyster populations in the chesapeake bay?

less oyster reproduction, overharvesting

what is an externality?

the impact of one person's actions on the well-being of a bystander

what is an example of a negative externality in the bay?

a farmer fertilizes their field and nutrient runoff leads to poor water quality in the bay

explain the steps of eutrophication

1. nutrient rich runoff from farms/agricultural areas into water.
2. nitrogen and phosphorus from runoff promote the growth of algal blooms that die quickly and sink to the bottom of the water source.
3. microbes use up a lot of oxygen and produce carbon dioxide to decompose algal blooms, leading to anoxic dead zones that either kill or drive out local species.

what are the biological consequences of eutrophication?

phytoplankton absorb sunlight and decrease the amount of light reaching the bottom of the bay, SAV/seagrasses don't have enough light to produce energy and die, species that rely on aquatic vegetation have no habitat/food source/less oxygen, some algal blooms are harmful to humans/pets/other aquatic species.

phosphorus pollution in the chesapeake bay continue to increase/are at their highest today

false--nitrogen/phosphorus levels are decreasing due to new policies

what is the "flush tax" aka chesapeake bay restoration fee?

a fee paid by MD residents to fund state water resource recovery facilities

while nutrient runoff from agriculture has decreased in the past 50 years, where has nutrient runoff increased?

stormwater

what is the largest source of nitrogen pollution to the chesapeake bay?

agriculture

what is wastewater?

water that leaves your house through drains

over the years, what has happened to the atmospheric deposition of nitrogen into the chesapeake bay?

it is decreasing due to air quality/fuel efficiency/acid rain reduction policies

where does atmospheric deposition of nitrogen into the bay come from?

fuel burning vehicles and power plants

which state has the largest remaining amount of nutrient reductions needed to meet its TMDL goal?

Pennsylvania

over the last 20 years, what has happened to the amount of undeveloped forest land?

it has decreased

over the past 20 years, what has happened to the amount of agricultural land?

it has decreased

over the past 20 years, what has happened to the amount of urban/suburban land?

it has increased

what happens to the bay's water quality after heavy rains?

it worsens

what were the goals of the first Bay Agreement?

reduce nutrient runoff, eliminate toxins, develop a strategy

what is a total maximum daily load (TMDL)?

a limit set by the EPA on nutrients/sediments entering the bay and a water quality standard that needs to be met for the bay's tributaries to be removed from EPA's "impaired" waters list

how do policymakers predict changes in water quality that could result from land use/policy change?

they can use the chesapeake bay watershed model to test outcomes under different scenarios using a complex computer simulation model

what factors contribute to increased sediment entering the chesapeake bay?

increased impervious surface, extreme storms/precipitation

what is a consequence of the loss of seagrasses caused by poor water quality?

benthic oxygen production decreases, which makes water quality even worse

what is a consequence of the lethal effect of dead zones on oysters?

less filtering of sediments/nutrients in water

what was the national pollutant discharge elimination system (NPDES)?

a system requiring permitting of “point sources” of pollution

responsibilities of the chesapeake executive council

policy direction for restoration and protection, marshalling public support, set goals for bay restoration, accountability

watershed implementation plan

states demonstrate how to meet the TMDL target set by the EPA

what are some methods the EPA uses to enforce TMDL?

requiring point source permits for pollutants, fine states for missing targets, providing scientific support and funding