Transcript Estuarine Dynamics David Nash and Jenny McDaniel Overview

Estuarine Dynamics
David Nash and Jenny McDaniel
Overview
• Definition of estuary
• Estuarine influences
• Intertidal estuary
• Subtidal estuary
• Producers
• Consumers
• Decomposers
What is an estuary?
Cowardin et al. 1977:
“ ...deepwater tidal habitats and adjacent
tidal wetlands which are usually semi-enclosed
by land, but have open, partially obstructed,
or sporadic access to the open ocean and in
which ocean water is at least occasionally
diluted by freshwater runoff from the land.”
Estuarine Boundaries
The limits of an estuarine system extend:
1) upsteam and landward to the place
where ocean-derived salts measure less
than 0.5 ppt during the period of
average annual low flow
Estuarine Boundaries
The limits of an estuarine system extend:
2) - seaward to a line closing the mouth of
a river,bay, or sound
- seaward to a line enclosing an offshore
area of diluted seawater with typical
estuarine flora and fauna
- seaward limit of wetland emergents,
shrubs or trees where these plants
grow seaward of the line closing the
mouth of a river, bay, or sound
Estuaries: 2 Major subdivisions
• Intertidal - those areas where the substrate is
periodically exposed and inundated by tides
including the associated splash zone
• Subtidal- those areas where the substrate is
continuously submerged
Estuarine influences
• oceanic tides
• currents
• precipitation
• runoff from the land
• evaporation
• wind
• river flow
• meteorological pressure centers
Estuarine influences...cont.
• salinity
• size and shape of estuary
• water temperature
• turbidity
• substrates
• erosion
• deposition
• pollution
Intertidal Estuary
Characteristics:
• high environmental stress
• low species diversity
• often dominated by salt marshes and flats
• transitional area b/w uplands and permanently
flooded estuaries and bays
• includes both terrestrial and marine organisms
Intertidal Estuary: Producers
Species occurrence limited by:
• salinity
• drainage
• temperature
• tidal influence
Intertidal Estuary: Producers
• nonvascular flora - various
micro/macrophytes including diatoms, bluegreen algae, red and brown algae, etc.
• vascular flora - diversity is low, Spartina
alterniflora tends to be the dominant
species.
Producers: nonvascular microphyte
substrates
• mud flats
• marsh pannes (unvegetated sand flats)
• creek banks
• soils of halophytic angiosperms
• macroscopic algae
• oyster shells
• submerged marsh vegetation
Producers: nonvascular macrophyte
substrates
• mud flats
• marsh pannes (unvegetated sand flats)
• creek banks
• soils of halophytic angiosperms
• oyster reefs
• shell banks
• pilings and sea walls
• surface and subsurface waters
Producers: nonvascular macrophyte
substrates…cont.
• dead and living spartina stems
• marsh periwinkle
Producers: Vascular Flora
Influenced by:
• water level fluctuations
• salinity
• substratum type
• acidity
• fire
• nutrient availability
• aeration
Producers: Vascular Flora…cont.
Influenced by:
• temperature
• light
• plant competition
• salt spray
• animal activity
• human activity
Subtidal Estuary
Characteristics:
• environmental factors fluctuate more
frequently and more widely than in either
freshwater or seawater systems.
• Abundant nutrients supplied by sediments,
seawater, freshwater, precipitation,
groundwater,microbial decomposition,
bacterial and algal nitrogen fixation, and
runoff from intertidal salt marsh and land
areas.
Subtidal Estuary: Producers
• Phytoplankton
• Macrophytes
Subtidal Estuary: Phytoplankton
Influenced and limited by:
• salinity
• temperature
• light intensity at surface
• light intensity below surface
• nutrients
• pollutants
Subtidal Estuary: Macrophytes
Macroscopic algae limited by:
• substrates (solid, permanent substrate often
absent)
• scouring action of the tides
• turbidity
Subtidal Estuaries
Productivity is limited by three separate, but
interdependent, units of primary production
• marshes and their resulting detritus
• benthic micro and macrophytes
• phytoplankton
Consumers
• Benthic meiofauna-animals living in the
sediments (0.5-.063mm in size)
- most of these animals are nematodes with
copepods second in abundance
Consumers
• Benthic macroinvertebrates - animals that live
in the sediments and are >0.5mm in size
- the number of these organisms is limited
due to the stressful environmental
conditions (salinity, drainage, temp, etc.)
- inverts play an important role of reworking
the benthic sediments (burrowers, etc.)
Benthic macroinvertebrates
marsh periwinkle
ribbed mussel
oyster reef
Benthic macroinvertebrates
fiddler crab
polychaete worm
Insects
• Insects are significant pathways of energy
flow within the marsh ecosystem
• Insect fauna is varied and abundant in almost
all salt marsh habitats
• Diptera (flies, mosquitoes, and midges),
Coleoptera (beetles), and Hemiptera (true
bugs) comprise about 75% of the species in
marshes
Insects
Hemiptera
Diptera
Coleoptera
Insects
• Most non-aquatic species tend to avoid areas
subject to tidal inundation
• Carnivrous insects- most common are spiders,
beetles, and mosquitoes
• Low plant diversity limits food sources for
herbivorous insects
examples: grasshoppers, ants
• Insects are also important prey items for
predators such as birds (marsh wren)
Fishes
• Most resident species move in and out with the
tide or remain in standing pools of water
- example: mummichog, sheepshead minnow
• Other species use the marsh for different life
stages
- example: mullets, spotted seatrout, spot
Fishes
Striped mullet
Spot
Spotted sea trout
Amphibians and Reptiles
• Few species are represented in the
saltmarshes of the southeast US
Amphibian examples:
Eastern narrowmouth
toad
Southern leopard frogs
Reptiles
Banded water snake
Diamondback
terrapin
Eastern glass lizard
Reptiles: American alligator
Birds
• Salt marsh vegetation serves as a base for
reproduction, feeding, and roosting activites
- examples:
long-billed marsh wren- defends its
feeding and breeding territory
individually
white ibis- colonial nesters remove large
amounts of marsh grasses to build nests
red-winged blackbirds- roost in marsh
Birds
long-billed marsh wren
White ibis
Red-winged blackbird
Birds
• Presence of birds helps to cycle nutrients
- dispersal of seeds
- fecal material fertilizes marsh plants and
has been shown to enhance growth
Birds
• Wood stork- federally endangered species
that relies on fish found in marshes for
primary food source
Birds
• Great egret- year round resident in estuarine
marsh habitat. Feeds on small fish, shrimp,
and crabs.
Birds
• Clapper rail- permanent resident that feeds,
nest, and roosts in the Spartina marsh.
Birds
• Willet- shorebird that is seen seasonally in
the estuarine marsh system. Feeds on
crustaceans, molluscs, and annelids.
Birds
• Marsh hawk- raptor that preys on clapper
rails and small mammals.
Herbivores:
Mammals
• Marsh rabbit-feeds on cordgrass, but
populations are limited due to predation by
marsh hawks
• White-tailed deer-tends to graze in the
higher marsh regions
Omnivore
Mammals
• Marsh rice rat- remains persistently in the
marsh. Feeds on cordgrass, crabs, and
insects.
Carnivores
Mammals
• Racoons- feeds heavily on crustaceans,
molluscs, and bird eggs and young
Carnivores
Mammals
• River otter- depends on fishes and crabs.
Has few predators, yet populations remain
low.
Decomposers: bacteria and fungi
3 primary roles:
• decomposition of dead organic matter
• conversion of indigestible plant material
(cellulose) to a form that is readily used by
detritivores and deposit feeders
• conversion of dissolved organic and inorganic
materials into consumable particulate matter
Subtidal estuarine consumers
Zooplankton
- animals that live in the water column
and are at the mercy of the currents
- able to tolerate salinity fluctuations up
to 12ppt during a single tidal cycle
- zoo. biomass is greatest in estuaries
- serve important role in estuarine food
web
- food for many larval and juvenile fish
Zooplankton...cont.
Zooplankton...cont.
Human impacts:
Effluent discharges- indirect effects
Channel dredging- decrease primary
production which in turn lowers zoo.
populations
Pesticides and heavy metals- not only
effect zoo.populations, but also impact
larval fish and invertebrates by causing
developmental delays, abnormalities, and
death
Benthic meiofauna
•Benthic meiofauna-animals living in the
sediments (0.5-.063mm in size)
- most of these animals are copepods,
including both interstitial and burrowing
species
- these animals are highly sensitive to both
temperature and oxygen fluctuations
Benthic macroinvertebrates
• Species diversity depends on 2 factors:
Substrate
silt, sand, or clay - high diversity
medium to fine grain sand- low diversity
clay and either silt or fine grain sandlow diversity
Benthic macroinvertebrates
• Species diversity depends on 2 factors:
Salinity
< 5 ppt (oligohaline waters)
5-18 ppt (mesohaline waters)
> 18 ppt (polyhaline/euhaline waters)
*
Species diversity tends to increase with
an increase in salinity
Benthic macroinvertebrates
amphipods, polychaetes, bivalves
Benthic macroinvertebrates
Sand dollar
Green Jacknife Clam
Commercially important
macroinvertebrates
White shrimp
Brown shrimp
Blue crab
Fishes
• Species composition is abundant and diverse
Spot
Atlantic croaker
Trophic relationships
Top Carn
Shark
1° Carnivores
Bay Anchovy
Herbivores
Mullet and Menhaden
Primary Producers
Reptiles
• One of the only reptiles truly found in the
subtidal estuarine system is the:
Diamondback terrapin
Birds
• Birds use the subtidal region for:
resting and feeding
•Species include:
Herring gull- scavenger
Ring-billed gull- scavenger
Laughing gull-scavenger
Brown pelicans- piscivore
Royal terns- piscivore
ect….
Birds
Herring gull
Ring-billed gull
Laughing gull
Birds
Brown pelican
Royal Tern
Mammals
• Only 2 consistent components of the subtidal
estuarine system:
River otter
Mammals
• Only 2 consistent components of the subtidal
estuarine system:
Atlantic bottlenosed dolphin
References
http://www-staff.lboro.ac.uk/~cvcfs/simulations/estuarinedynamics/frame.html
http://www.tulane.edu/~eeob/Courses/Ecology_Materials/estuary_biome.html
http://inlet.geol.sc.edu/nerrsintro/nerrsintro.html
http://riceinfo.rice.edu/armadillo/Galveston/Chap8/ch8.estuarine.food.html
http://www.geog.ucl.ac.uk/~jfrench/EEI.html
http://www.nwrc.gov/about/web/nutrient.html
http://www.ucc.uconn.edu/~skoog/Michaelb.htm
http://www.environment.gov.au/portfolio/anca/mpa/c_ray.html
http://www.epa.gov/nep/
http://www.estuarylive.org/
http://www.epa.gov/ceisweb1/ceishome/atlas/maiaatlas/maia__condition_of_the_mid.html
http://pelotes.jea.com/fidcrab.htm
http://oak.conncoll.edu/~dmwhi/milfordpaper.html
http://www.tpwd.state.tx.us/expltx/eft/gulf/cspecies/wildlife.htm
http://www.st-and.ac.uk/~seeb/pheromone/pcWorms.html
References…cont
http://ag.arizona.edu/tree/eukaryotes/animals/arthropoda/hexapoda/hemiptera/hemiptera.html
http://www.mdarchives.state.md.us/msa/mdmanual/01glance/html/symbols/reptile.html
http://www.mbr-pwrc.usgs.gov/id/framlst/i1840id.html
http://www.kwic.com/~pagodavista/harrier.htm
http://www.cviog.uga.edu/Projects/gainfo/wildlife/marshrabbit.htm
http://employeeweb.myxa.com/rrb/Audubon/VolV/00541.html
http://donb.furfly.net/malheur/birds/willet.html
http://www.otternet.com/galleries/naotter/
http://www.csc.noaa.gov/otter/htmls/ecosys/ecology/estuary.htm#top
http://www.bio.swt.edu/Lavalli/guides/phylum_arthropoda.htm
http://endangered.fws.gov/i/B2S.html
http://www.camacdonald.com/birding/DesJardin/LaughingGull.html