Lecture 10 - Estuaries and Wetlands- BIO OCE

estuary

partially enclosed region where larger rivers enter the sea

characteristics of estuaries

high primary production, large fish/bird populations, low alpha diversity, seasonal variability, influence of tides, strong salinity gradients, urbanized

what are the environmental problems in estuaries

pollution, eutrophication, habitat destruction, overfishing, HABs

what is primary production in estuaries limited by

turbity (light penetration) more than nutrients

how are estuaries urbanized

sources of freshwater, transportation, fisheries, recreation, waste disposal

how are estuaries sites of intense conflicting human interests

since they are recreations and waste disposal, there is competing interest for human health

three types of river deltas in estuaries

fan shaped delta, bird foot delta, and estuarine delta

example of fan shaped delta

nile

example of bird foot delta

mississippi

example of estuarine delta

chesapeake bay and san francisco bay

fan shaped delta

bird foot delta

estuarine delta

estuarine communities

saltmarsh, seagrass bed, mudflat/sandbar, pelagic

synonym mudflat

sandbar

primary producers in saltmarsh

marshgrasses or mangroves

primary producers in seagrass bed

seagrasses

primary producers in mudflats

epipsammic algae

primary producers in pelagic

phytoplankton

higher trophic, secondary, and primary in saltmarsh

higher = mammals/birds/reptiles, secondary = birds/insects, primary = marshgrasses/mangroves

higher trophic, secondary, and primary in seagrass bed

higher = benthic macrofauna/fish, secondary = snails/crustaceans primary = seagrasses

higher trophic, secondary, and primary in mudflat

higher = benthic macrofauna/fish, secondary = meiofauna primary = epipsammic algae

higher trophic, secondary, and primary in pelagic

higher = fish, secondary = zooplankton primary = phytoplankton

how do marshgrasses enter the food web

not grazed, enter detritus food web

estuarine species richness

low

why is species richness low in estuaries

due to stressful conditions, high change in salinity

major zooplankton in summer in lower chesapeake bay

95+% acartia tonsa

two species of comb jellies in winter in lower chesapeake bay

Mnemiopsis leydii, beroe ovata

chesapeake bay salt marsh

spartina alterniflora

salt marsh facts

tidal flooding, contain highly tolerant grasses, trap sediments, produce microhabitats, biogenic, provide ecosystem services

what are salt marshes caused by

tidal flooding

biogenic environment

dominant species structure the physical habitat

how do salt marshes provide ecosystem services

they are nurseries for commercially important fish, buffer against storms, act as a filter to prevent nutrients from washing into the bay, and are a recreation service

estuarine turbidity maximum

entrapment zone where salt wedge traps particles and keeps them suspended by tidal currents

salt wedge

a dense, wedge-shaped layer of marine saltwater that intrudes landward along the bottom of an estuary beneath a layer of less dense, outbound freshwater

how is salt wedge defined

1ppt isohaline intersects the bottom

characteristics of estuarine turbidity maximum

high zooplankton biomass, anadromous fish depend on food supply in etm

what is the mechanism of retention of plankton and micronekton

salt wedge trapping particles and keeping them suspended by tidal currents (ETM)

vertical migration in etm

behavior that does zooplankton times migration to coincide with tides to help them remain stationary in estuary

anadromous

fish species that migrate up rivers to spawn

gravitational circulation

net internal motions caused by horizontal density gradients

how does the gravitation circulation work in estuaries

denser fluid flows along bottom and lighter fluid at surface to restore vertical stratification

what happens when gravitational circulation is at a longitudinal salinity gradient

net landward current at bottom and seaward compensating current of fresh water at surface

why is methane less abundant in the ocean than freshwater

sulfate is more present, and it produces more energy than methane in seawater, instead fermentation is done and produces large amounts of methane in freshwater

coastal blue carbon

carbon captured by living coastal and marine organisms and stored in mangroves, salt marshes, and seagrass meadows

what is the largest natural source of methane globally

freshwater wetland

what is the sink of blue carbon

saltwater wetlands, kelps, and seagrasses

what fraction of methane comes from wetlands

1/3

what is the largest estuary in the US

chesapeake bay

average depth of cheseapeake bay

21ft

how wide is chesapeake bay

3 miles wide at annapolis, 30 miles at potomac

why did oysterbeds disappear

due to overfishing and parasites

why are oysters returning in chesapeake bay

extensive restoration efforts

what is the dominant phytoplankton in chesapeake bay

microplankton (dinoflagellates and diatoms)

what are examples of dinoflagellates in chesapeake bay

Margalefidinium polykrikoides

what are examples of diatoms in chesapeake bay

coscinodiscus

what zooplankton are dominant in chesapeake bay

copepods acartia tonsa

what jellyfish are common in chesapeake bay

comb jellies mnemniopsis leidyi and bay nettle (chrysaora)

keystone species in chespeake bay

oysters crassostrea virginica

fish common in chesapeake bay

white and yellow perch, striped bass, herring

what is increasing in chesapeake bay

anoxia dead zones

what percent does the san joaquin drain in california

40%

how much water flows through the san francisco estuary

16%

what are diked islands in the san francisco estuary

former tidal marshes or wetlands that have been walled off by levees and dikes to prevent tidal flooding

what is X2

distance from golden gate to where salinity is 2 ppt, It defines the dynamic boundary where fresh water from the rivers mixes with salt water from the ocean

what does it mean if the distance is shorter in X2

it means there is more freshwater input, smaller X2 means more flooding and better for the ecosystem

eutrophication

excess nutrients

delta

landform created at the mouth of a river where it dumps stuff

why is X2 important

useful ecosystem indicator and relationship to fish production

what is the ecological significance of X2

allows habitat expansion at high flow for herring to spawn, vertical migration is more efficient at high flow, stronger egg dispersal, more food abundance