Low(er) Salinity Marshes

Freshwater Salinity

< 0.5

Oligohaline Salinity

0.5 - 5

Mesohaline

5-18

Polyhaline Salinity

18-30

Euhaline Salinity

> 30

Salinity

the amount of salt in water (or soils)

When OM production is high

warm, moist climates where primary

productivity is high → therefore high litter

production and high accumulation

When OM decomposition is low

colder, wetter climates where

decomposition slows

Temperature

higher temperature promote biological activity (to a point); lower temps slow bacterial metabolism

Moisture

wetter conditions can result in anoxia and anaerobic microbial respiration (less efficient & slower decomp)

pH

OM decomposition can slow in acidic conditions

Litter Quality

if plant residues (“biogenic materials”) are refractory (not easily broken down, e.g. wood), then decomposition slower than with labile materials (e.g. leaves)

Hydroperiod

Alternating wet/dry cycles may lead to optimal litter decomposition rates

Nutrient Enrichment

excess nutrients stimulate primary productivity (more OM input!) AND microbial respiration

Landscape Position

depressions accumulate organics, slopes and convex land surfaces tend to shed organic debris

Broad classes of aquatic plants

Emergent:

rooted in the soil or sediment

• Leaves and stems grow upwards, extending

out of the water's surface

• Can include floating-leaved plants

Broad classes of aquatic plants

Submerged:

vascular plants that grow almost entirely underwater in freshwater, brackish, or marine habitats

• Rooted

• Floating (unattached)

Aquatic (submerged aquatic vegetation)

NATIVE

Utricularia spp: bladderworts

• Vallisneria americana: wild celery

• Potamogeton spp: pondweeed

Aquatic (submerged aquatic vegetation)

INVASIVE

Myriophyllum spp: water milfoil, parrot

feather

• Hydrilla verticillata: hydrilla, water thyme

• Alternanthera philoxeroides: alligator weed

Emergent Plant Examples

NATIVE

Peltandra virginica: arrow-arum

• Pontederia chordata: pickerelweed

• Typha spp: cattail

• Sporobolus/Spartina cynosuroides: big

cordgrass

• Persicaria punctata: dotted smartweed

Emergent Plant Examples

INVASIVE

Phragmites australis: giant or common reed

What are key characteristics of Utricularia spp. (bladderwort)?

Traits:

• Forb

• Carnivorous

• Bladders with hairs

• Attract and trap prey inside

Examples + Info:

• Utricularia macrorhiza = common bladderwort

• Utricularia juncea = southern bladderwort

• Vulnerable in North Carolina

What are key characteristics of Vallisneria americana (wild celery / eelgrass)?

Traits:

• Forb

• Perennial

• Fast-growing

Importance:

• Vital food source

• Stabilizes sediment

• Popular in aquaria

What are key characteristics of Potamogeton spp. (pondweeds)?

Traits:

• Some species native, some invasive

• Forb

• Perennial

Examples + Info:

• P. perfoliatus: grows shallow → deep (up to ~6.5 m), tolerates clear & turbid water, adapts to low light

• P. pusillus: intolerant to eutrophication

• P. diversifolius

• P. crispus: invasive

What are key characteristics of Hydrilla verticillata (hydrilla)?

Traits:

• Forb

• Rhizomatous

• Can grow up to ~25 ft tall

Impact + Info:

• Introduced in 1960s (aquarium trade)

• Grows well in turbid waters

What are key characteristics of Myriophyllum spicatum (Eurasian watermilfoil)?

Traits:

• Forb

• Perennial

• Can grow >2 m (~8 ft)

Habitat + Impact:

• Slow-moving or protected fresh & slightly brackish water

• Cannot tolerate strong waves/currents

• Reproduces asexually from stem fragments

• Accidentally introduced via aquarium trade

What are key characteristics of Alternanthera philoxeroides (alligator weed)?

Traits:

• Forb

• Perennial

Impact + Control:

• Introduced to SE U.S. in 1880s (from Trinidad via ship ballast water)

• Forms dense mats (can exceed 30 ft wide)

• Clogs dams → contributes to flooding & erosion

• Biological control: flea beetles (Agasicles hygrophila) & stem-borer moths (Arcola malloi)

• Control insects effective elsewhere but do not overwinter in NC

What are key characteristics of the Pontederia–Peltandra–Sagittaria association?

Traits:

• Forbs

• Rhizomatous

• Full sun

• Dominance varies seasonally

Importance:

• Stabilizes soil

• Attracts birds (especially ducks)

What are key differences between Typha angustifolia and Typha latifolia (cattails)?

Traits:

• Both are cattails (forbs)

Differences:

• Typha angustifolia = narrow-leaved cattail, more salt tolerant

• Typha latifolia = broad-leaved cattail

What are key characteristics of Typha spp. (cattails)?

Traits:

• Forb

• Perennial

• Male flowers above female flowers on same stalk

Reproduction + Structure:

• Female flowers have long hairs to catch pollen

• After pollination, male part disintegrates

• Leaves the familiar “cattail” (female portion)

Spartina/Sporobolus cynosuroides

True grass (Poaceae)

• Perennial

• Tall (1 – 4 m)

What are key characteristics of Phragmites australis (common reed)?

Traits:

• True grass

• Rhizomatous

• Can grow up to ~20 ft tall

Impact + Info:

• Some subspecies native, but invasive form likely non-native

• Introduced via shipping ballast (1800s)

• Found on every continent except Antarctica

Spread Factors:

• Disturbance (pollution, dredging, hydrologic changes, sedimentation)

• Increased salinity (fresh → brackish)

• Higher nutrient levels

Grazer

generally refers to an animal that directly consumes living plants

(and/or algae)

Detritivore

• Animals that feed on dead organic matter

• Get most nutrients from decomposers (since they can’t break down things like cellulose)

• Help decomposers by breaking up material and mixing sediments

• This improves oxygen flow in the environment (a loose mutualism)

Suspension feeder

consuming material / organisms suspended in the water column. Can be plankton or resuspended detrital material (andassociated decomposers)

Predators

Generally refers to animals consuming animals.

Parasites

definition can get fuzzy. Dictionary definition: an organism living

in or on another or species (host) and benefits by deriving nutrients from the host

Insects

• Found in tidal freshwater and low-salt (oligohaline) areas

• Diversity decreases as salinity increases

• Not very common in marine environments

Traits + Roles:

• Have juvenile and adult stages

• Have exoskeletons

• Very successful group overall

• Can be grazers, detritivores, or predators

• Roles can change as they develop

• Can dominate freshwater marsh macrofauna

Environment:

• Many species are seasonal

• Wet/dry periods affect presence in oligohaline marshes

Examples:

• Dragonfly larvae

• Beetle larvae

• Chironomid (midge) larvae

• Mosquito larvae

Crustaceans

Traits:

• Diversity increases with salinity

• Found across salinity gradients

• Exoskeleton

• Some have larval stages, others brood young

• Very successful in aquatic habitats

Ecology:

• Roles: grazers, detritivores, predators, parasites

• Roles can change with life stage

• Some are permanent residents, others temporary users

• Strong seasonal and environmental effects

Examples:

• Crayfish

• Amphipods (Gammarus tigrinus, Corophium)

• Copepods

• Blue crab

Annelids and Nematodes

Annelids (worms):

• Oligochaetes (earthworms) common in freshwater and land

• Polychaetes dominate marine/estuarine systems

• Diversity of polychaetes increases in saltwater

• Oligochaetes decrease with higher salinity

• Some used as indicator species

Nematodes:

• Very abundant in all habitats

• Mostly very small

• Poorly studied in aquatic systems

Ecology (both):

• Grazers, detritivores, predators, parasites

• Roles can change with life stage

Examples:

• Nematodes

• Clam worm (Nereid polychaete)

• Marsh oligochaete

• Streblospio (polychaete)

Bivalves and gastropods

Bivalves (clams, mussels, scallops):

• More diverse with increasing salinity (but still found in freshwater)

• Mostly filter feeders or detritivores

• Can be very abundant (e.g., Rangia, Corbicula in Chesapeake Bay)

• Less common in Cape Fear estuary

• Can affect water quality through filtration

Gastropods (snails, slugs):

• Found in freshwater, marine, and terrestrial systems

• Most diverse in marine environments

• Roles: grazers, detritivores, predators

• Include endemic and threatened species

Interactions:

• Plant–animal mutualisms (e.g., Hydrilla and Rangia)

• Clams provide filtration; plants provide refuge

Examples:

• Rangia

• Spiny mussel

• Ramshorn snail

Resident Fish

Habitat + Behavior:

• Use channels and vegetation edges for protection

• Most are not restricted to marsh systems

• Must leave marsh when exposed (tides)

• Distinct communities in freshwater vs. saltier areas

Ecological roles:

• Grazers / detritivores

• Predators

Examples:

• Sunfish (bluegill, crappie)

• Killifish

• Shiners

• Bass

• Carp

• Gobies

• Many others

Temporary Fish

General pattern:

• Move between freshwater and estuarine habitats

• Use these areas during migration or as juveniles

• Include many commercially and recreationally important species

Migratory species:

• Striped bass

• Eels

• Sturgeon

• Shad

• Herring

• Pass through but still use habitat while moving

Juvenile use:

• Flounder

• Spot, croaker, drum

• Low-salinity habitats are important nursery areas

Concerns / impacts:

• Striped bass, sturgeon, eels: low numbers (habitat loss, overfishing, dams)

• Flounder: declining (overfishing + habitat loss)

• Blue catfish: introduced, invasive problem species

Shown: flounder, croaker, sturgeon, blue catfish

Replies

Types:

• Several turtle species (including diamondback terrapin and freshwater turtles)

• Alligator

• Snakes

Habitat range:

• Freshwater to mesohaline systems

Key info:

• Alligator was once endangered but is now recovering

• Reptiles can strongly influence and respond to habitat changes

Examples shown:

• Diamondback terrapin

• Alligator

• Python

• Cottonmouth

• Alligator hole (habitat feature)

• Alligator nest

Birds and mammals

General:

• Many bird and mammal species use these systems

Mammals (examples):

• Muskrat: habitat impacts, economic value, food use

• Beaver: habitat engineering, economic value

• Mink: predator of other aquatic mammals (freshwater/oligohaline systems)

Birds:

• Many species utilize these habitats (no specific restriction noted)

Economic Value

Economic value (fisheries & recreation):

• Habitat for commercially important fishery species

• NC examples: flounder, striped bass, blue crabs (upper Albemarle Sound), croaker

• Supports recreational fishing and tourism

• Important for nature-based tourism

Ecological value:

• Improves water quality

• Filters water and sediments

• Buffers sediment runoff from uplands

• Helps stabilize shorelines

Enviromental Impacts

Weather & water inputs:

• Storms and upstream rainfall affect conditions

• Flooding events

• Droughts

• Upland runoff inputs (sediment and nutrients)

Physical changes:

• Changes in salinity and water flow strongly affect the system

• Increased sediment input can alter habitats

Biological effects:

• Weather can influence insect populations

• Impacts recruitment of species with planktonic larvae

• Affects species that migrate through or use areas as juveniles

Challenges for Tidal Freshwater and Oligohaline Marsh fauna

• Land use practices

• Overfishing

• Contaminants

• Introduced species

• Climate change