EX 3 Ch 24/25 - Aquatic, Coastal, & Wetland Ecosystems

Aquatic Ecosystems

classified based on features of physical environment; salinity is major feature influencing aquatic organisms; all aquatic ecosystems are linked directly or indirectly as parts of hydrological cycle

Marine (Saltwater) Ecosystems

open-water, coastal

Freshwater Ecosystems: Lotic

flowing water; rivers and streams

Freshwater Ecosystems: Lentic

nonflowing water; ponds, lakes, wetlands

Freshwater: Lentic Systems

lakes and ponds are inland depressions that contain standing water

Lentic: Ponds

typically shallower and smaller than lakes; sunlight reaches bottom in most areas; rooted plants to grow across

Lentic: Lakes

typically larger and deeper than ponds; may have areas where sunlight cannot reach bottom; usually has distinct lake zones with thermal stratification

Florida Lakes

most are shallow, mix frequently preventing stratification, have submersed plants along whole basin, have distinct lake zones, and formed as sinkhole (solution) lakes from erosion of limestone; over 7700 lakes in FL, imp bc they support biodiversity and provide natural resources

Lake Origins: Glacial Erosion & Deposition

Kettle lakes form when large chunks of glacial ice break off, become buried in sediment, and later melt; Pothole lakes formed where glaciers carved out a depression that later filled

Lake Origins: Rivers Damming Themselves with Sediment

Oxbow Lakes are U-shaped bodies of water formed when a river meander becomes cut off from main channel through erosion and deposition

Lake Origin: Tectonic or Volcanic Activity

tectonic lakes form by faulting or subsidence of Earth’s crust; crater lakes form in caldera of extinct volcanoes

Lake Origins: Geological Dissolution

solution or sinkhole (karst) lakes form thorough chemical dissolution of soluble bedrock

Lake Origins: Nongeological Activity

lakes are formed by beaver dams, human-created dams, quarries, and surface mines

Lake Zonation

from shallow to deep: littoral zone → limnetic zone → profundal zone → benthic zone; nature of life varies in different zones

Lake Zonation: Littoral Zone

shallow, nearshore area; life most abundant; richest in aquatic life bc sediments accumulate and keep water depth low, sunlight reaches bottom, and plants provide food and habitat

Lake Zonation: Limnetic Zone

open water; phytoplankton act as main primary producers in open water; zooplankton feed on phytoplankton and are key link in energy flow; spring and fall turnover bring bottom nutrients to surface causing phytoplankton bloom followed by population decline once nutrients depleted; fish make up most of nekton and distribute themselves based on food, oxygen, and temp

Lake Zonation: Profundal Zone

deeper water below reach of sunlight

Lake Zonation: Benthic Zone

bottom of lake; contains organic debris that sinks from above or washes in from shore; typically dominated by anaerobic bacteria and periphyton

Lakes by Nutrients: Oligotrophic

low in nutrients, clear water, supports fewer plants and algae

Lakes by Nutrients: Mesotrophic

moderate nutrient levels with balanced amount of plant and algal growth; intermediate clarity and oxygen

Lakes by Nutrients: Eutrophic

high in nutrients, leading to dense plant and algal growth; often murky with low oxygen in deeper water due to decomposition

Lakes by Nutrients: Dystrophic

brown, tea-colored lakes rich in organic acids; low nutrients, low pH, and limited productivity

Streams

often begin as springs, seeps, glacier melt, or as outflows from ponds and lakes; as they move downhill, their path and flow are shaped by landscape; stream characteristics change as it moves from source to destination

Stream Parts: Headwaters

small, fast, and straight; often with rapids and waterfalls

Stream Parts: Midstream

as slope decreases, stream slows down, begins to meander, and deposits sediment

Stream Parts: Mouth

where river empties into lake or ocean; velocity drops sharply, sediment settles

Stream Order

streams grow larger as they travel downstream and join with other streams; stream’s order increases only when 2 streams of same order meet

Stream Order: 1st-order

small headwater stream with no tributaries

Stream Order: 2nd-order

forms when 2 1st-order streams join

Stream Order: 3rd-order

forms when 2 2nd-order streams join

Stream Order: Headwater Streams

of orders 1-3

Stream Order: Medium-Sized Streams

of orders 4-6

Stream Order: Rivers

of orders 7-12; ex: Amazon is 12th, Mississippi is 10th, St. Johns is 3rd

Flowing Water

organisms living in flowing water face challenge of staying in place instead of being swept downstream

Flowing Water: Fast Moving Stream Adaptations

streamlined bodies to reduce drag; flattened bodies and broad limbs that help insect larvae cling to rocks; protective cases that anchor larvae to stones; sticky undersides in snails and planaria for gripping surfaces; filamentous algae cling tightly substrate

Flowing Water: Slow Moving Stream Adaptations

water moves gently, so organisms don’t need strong anchoring structures; tolerate lower oxygen and typically use gills or air-breathing strategies (siphons); feed on fine organic particles (collectors, filter feeders); live in soft bottoms (burrowers, detritivores); support more plants and algae, providing food and habitat

Stream Feeding Roles: Shredders

break down leaves and coarse organic matter while feeding on microbes growing on them

Stream Feeding Roles: Collectors

filter or gather fine particles created by shredders

Stream Feeding Roles: Grazers

scrape algae from rocks and other surfaces

Stream Feeding Roles: Gougers

burrow into waterlogged wood for food and shelter

Stream Feeding Roles: Predators

insect larvae and fish that feed on grazers and detrital feeders

River Continuum Concept

because each feeding group thrives under different conditions, their abundance changes predictably from headwaters to midstream to downstream

Freshwater Wetlands

diverse group; when water spreads into low, flat areas; stay flooded or water-saturated for much of year

Freshwater Wetlands Examples

marshes, swamps, bogs

Wetlands Topography: Basin

form in low depressions such as shallow basins or former lakes; water mainly moves up and down (vertical flow)

Wetlands Topography: Riverine

occur along rivers and streams; periodically flooded and have one-way, downstream flow

Wetlands Topography: Fringe

found along edges of large lakes; influenced by rising and falling lake levels with back-and-forth (bidirectional) flow

Freshwater Wetlands: Hydrophytic Plants

adapted to grow in water or in oxygen-poor, saturated soils

Freshwater Wetlands: Obligate Plants

must have saturated soils; exs: pondweeds, pond lily, cattails, bulrushes, bald cypress

Freshwater Wetlands: Facultative Plants

can grow in wet or dry soils; exs: sedges, alders, red maple

Freshwater Wetlands: Marshes

wetlands dominated by emergent herbaceous vegetation; wet grasslands (reeds, sedges, grasses, cattails

Freshwater Forested Wetlands: Deep-Water Swamps

are tree dominated; cypress, tupelo, swamp oaks

Freshwater Forested Wetlands: Shrub Swamps

are shrub dominated; alder, willows

Freshwater Wetlands: Riparian Woodlands

occasionally or seasonally flooded by river waters

Freshwater Wetlands: Peatlands

wetlands where organic matter (peat) builds up over time

Freshwater Wetlands: Peatland Fens

peatlands fed by groundwater

Freshwater Wetlands: Peatlands Bogs

peatlands that rely on rainwater

Rivers Approach Coast

freshwater wetlands transition into coastal wetlands: salt marshes and mangroves

Coastal Wetlands: Salt Marshes

occur in temperate latitudes where coastlines are protected from wave action; tides and salinity shape marsh and create distinct plant zones

Salt Marshes: Low Marsh

seaward edge; dominated by tall cordgrass, which tolerates high salinity and has hollow stems that move oxygen to roots

Salt Marshes: High Marsh

flooded only at high tides; supports short cordgrass and other plants, which are less salt tolerant

Coastal Wetlands: Mangroves

found along tropical and subtropical coasts where wave action is absent, sediments accumulate, and the muds are anoxic; adaptations include prop roots providing support and pneumatophores taking in oxygen

Estuary

rivers complete journey through river continuum and eventually meet ocean; semi-enclosed part of coastal ocean where freshwater joins saltwater

Estuary: Salt & Freshwater Mix

creates countercurrent that traps nutrients in estuary; rivers bring little nutrient input, but tides bring in nutrients and oxygen from sea; vertical mixing keeps these nutrients inside estuary instead of letting them wash out

Estuary: Productivity

highly productive environments that serve as imp breeding and nursery grounds for many fish, crustaceans, and other marine organisms

Estuary: Oyster Beds

imp communities; filter water improving clarity and reduce excess nutrients; create habitats by providing 3D structure that shelters fish, crabs, shrimp, and other invertebrates; stabilize shorelines as reef structures reduce erosion by breaking wave E

Estuary: Rooted Aquatic Plants

imp in shallow estuaries; stabilize sediment which decreases erosion; produces oxygen through photosynthesis; provides nursery habitat so animals can hide within plants; support food webs as basis of food web

Intertidal Zone

transition btwn terrestrial and marine environments; when land meets water, a transition zone forms, creating many unique ecosystems; coastal environment sit btwn land and sea; classified by geology and substrate

Intertidal Zone: Rocky Coasts

erosional landforms where interface btwn land and sea is made of hard, resistant rock; typically found along active continental margins

Intertidal Zone: Sandy Coasts

form when rocks inland and along the coast break down into tiny pieces; rivers and waves carry this material and deposit it along shoreline as sand

Open Ocean

conditions change dramatically with depth; light, nutrients, temp, pressure vary across ocean zones, shaping marine diversity and adaptations needed for survival

Ocean Cover

ocean covers about 70% of Earth and is extremely deep (over 10 km in some places); only a small part of it gets sunlight compared to huge V of water; all oceans are connected by currents, shaped by waves and tides, and share similar salt levels

Ocean Stratification & Zonation: Benthic Zone

bottom region

Ocean Stratification & Zonation: Pelagic Zone

whole body of water; multiple vertical zones based on depth; light declines rapidly with depth: epipelagic (sunlight), mesopelagic (twilight), bathypelagic, abyssopelagic, and hadalpelagic (complete darkness)

Pelagic Communities

lack supporting structures and framework of large, dominant plant life; dominant autotrophs are phytoplankton, and their major herbivores are tiny zooplankton

Deep-Sea Adaptations

occur throughout lower ocean zones

Deep-Sea Adaptations: Bioluminescence

most common in mesopelagic, where about 2/3 of species produce light

Deep-Sea Adaptations: Extreme Feeding Adaptations

huge jaws, lures, expandable stomachs; become even more pronounced in deeper zones where food is very scarce

Pelagic: Microbial Loop

small-scale food chain within plankton; photosynthetic nanoflagellates and cyanobacteria are responsible for large part of photosynthesis in sea; heterotrophic bacteria feed on wastes produced by these organisms; heterotrophic nanoflagellates eat bacteria ad pass E up food chain

Ocean Productivity

marine primary productivity happens only where light and nutrients are available; coastal areas have highest productivity bc shallow waters mix easily and upwelling often adds extra nutrients

Ocean Productivity: Thermocline

blocks nutrients from rising, so productivity depends on seasonal mixing when thermocline breaks down and upwelling that brings deep, nutrient-rich water to surface

Freshwater & Marine Ecosystems: Human Activity

negative impacts on water quality; extra nutrients cause huge phytoplankton blooms; when they die, they are broken down by bacteria, which depletes oxygen; leads to anoxic or dead zones where marine life cannot survive