WQ - Coral & Estuaries

Estuary definition

An area of brackish water that has one or more streams/rivers flowing into it, AND that has a free connection to the open sea. They're VERY dynamic systems (daily changes in temp, salinity, turbidity, depth etc in response to the tides.) Therefore very strong season variation in fish communities.

What is the role of coral in aquatic ecosystems and for humans?

• Provides shelter, breeding grounds, and resting grounds for organisms
  - Partially makes up sand (broken down coral skeletons.)
  - Supports filter feeders and photosynthetic plants
  - Helps supply fisheries, support businesses through tourism/recreation, and have possible medical potential.
  - Helps reduce impact from storms, waves, and floods-- saving infrastructure and lives

Tell me about coral bleaching and its cause.

Pollution, unsustainable farming practices, and climate change are causing ocean temps to rise, AND also causing acidification.
- Causes coral bleaching -- when coral polyps expel their symbiotic algae in response to a stress event. Increased vulnerability, and risk of disease etc; death.

Estuary organisms that're

Primary producers

Primary consumers

Secondary consumers

1: phytoplankton (main) e.g. dinoflagellates/diatoms, seaweeds

2: Zooplankton, clams, snails

3: eels, herons,crabs

Estuary organisms that're

Apex predators

Sea otters, sharks

Adaptations of estuary organisms (4)

• “Caspian strip” made of lignen and suberin in root’s endodermis forces water to enter via cells’ selectively-permeable membranes, filtering out excess salt

• Blue crabs retreat into their stable-salinity/temp burrows during high tide, avoiding exposure to more extreme salinity/temps.

• Mollusks close their shells in more extreme conditions to wait it out

4 reef-building organisms and how

Aka hermatypic organisms

Stony coral (explained in other card)

Coralline Red Algae (explained in other card)

Oysters/bivalves (veliger becomes pediveliger (larval stages), and they cement themselves onto surfaces, becoming a spat. Then, builds up)

Halimeda (after death, it adds to calcium deposition of calcium carbonate (e.g. aragonite); builds up over time)

How do coral form?

General life cycle

• Coral larvae (“planula”) get carried by currents/move via cilia, and irriversably settle/attach to a hard submerged surface (settling: “recruitment”). They're very attracted to ones with crustose corraline algae (CCA), which help cement the reef together, grow in encrusted formations on reef, and send chemical signals at coral to settle there.

• After recruitment, it turns into a polyp, secretes calcium carbonate (siphoned from water), and begins to expand, and split in two once it gets to a certain size (budding). Repeats until a colony is formed.

  • Calcification, where Ca-ATPase pumps Ca into extracellular calcifying fluid (ECF) while pumping H out. This raises the fluid’s pH, turning dissolved bicarbonate into carbonate used to expand/build skeletons.
    
    

Only hard corals make reefs.

Soft corals land on the calcium carbonate of hard corals to start off. They can't form reefs because they're fleshy/soft; their sclerites keep their shape, but they can't

Endemic

Native

Estuary organisms and human disease

Transmit human disease via filter feeders like shellfish (the disease bioaccumulates at their tissue.)

Primary productivity of coral reefs

Primary productivity: rate at which energy is converted to organic substances by photosynthetic producers

Extremely high due to mutualistic relationship with zooxanthellae.

Largest coral system

Great barrier reef (Australia)

Acidity’s effect on calcium carbonate

CaCO3. Calcifying organisms rely on it to e.g. build their skeletons.
Too low pH = too many H ions, leading to production of HCO_3- (bicarbonate), a form unusable by them.

Coral reef organisms that’re: Primary producers, primary consumers, secondary consumers

Primary producer: zooxanthellae, cyanobacteria, phytoplankton, seaweed

Primary consumer: Zooplankton, parrotfish, green sea turtles

Secondary: Coral polyps, jellyfish, stingrays

Coral reef organisms that’re:

Tertiary consumers

Quaternary consumers,

Tertiary: puffer fish, barracuda, angelfish

Quaternary: Reef sharks

Coral reef restoration techniques (secksual vs asecksual) (one each)

Secksual:

• Coral IVF - Take eggs/sperm (from e.g. fine mesh nets) during natural spawning events, and let them fertilize each other. Then release the larvae and allow settlement

Asecksual:

• Fragmentation, aka coral gardening - Take off small part of a donor coral (20% max) /transplant it on degraded reefs or artificial reef structures.

Coral-algal phase shifting

When coral cover of the substrate is reduced in favor of macroalgal (e.g seaweed) dominance.
Often caused by coral bleaching, storm damage, etc. e.g. eutrophication can speed it up.

Mangroves as carbon sinks

Mangroves sequester up to 4x more carbon per hectare, up to 10x faster, than tropical rainforests. called “coastal blue carbon”

Stores up to 90% of their carbon underground in their waterlogged soils, which makes things harder to decay, and the cabron trapped in there for long time periods.

How coral reefs have been ecologically harmed and effects (4)

• Sedimentation (smothers coral/their ability to grow, reproduce, etc)

• Eutrophication

• Toxic substances e.g. heavy metals, herbicides (which harm the zooxanthellae), oil spills (which damage sex cells in water), etc

• Overfishing (removes herbivorous fish that keep track of algal populations)

2 recently killed coral species

• Elkhorn coral

• Staghorn coral

Why are estuaries important to humans and ecologically?

Humans:

• Are a tourism and recreation hub (jobs provided; economic importance)

• Major producer of food e.g. fish

• Buffer for storms and flood water

Ecologically:

• Protects communities e.g. mangrove forests from wave energy (reduces wave height via e.g. drag from aquatic vegetation)

• Organisms e.g. salt marsh plants and oysters help remove pollutants from water

• Diversity in physical conditions, nutrient availability, and salinity supports lots of habitats/organisms

Largest estuary in U.S.

Largest estuary in world

• Chesapeake bay

• St Laurence estuary

Types of coral reefs (3)

Fringing: Most common. Forms a border along shoreline/surrounds islands; separated from them via shallow lagoon. 2 parts: Reef flat (closest to shore) and reef slope (faces ocean)

Barrier: Borders shorelines at greater distance; separated from their adjacent landmass via open, often deep water.
Atoll: Forms when fringing reef forms around a volcanic island, which completely sinks, while the coral keeps growing upward. Circle or oval, with central lagoon.

Coral and algae competition

Planula might compete for space with algae, sponges, other coral, etc.

Coral itself can attack for resources via their cnidocytes.

Algae: For space. E.g, algae can cover coral, reducing zooxanthellae photosynthesis.

Requirements for coral reef formation

Clean water (zooxanthellae can't photosynthesize if too turbid), temps 73-84F, and salinity of 32,000-42,000ppt

Brooding vs broadcast spawning in coral

#1: Internal fertilization; male sperm in water column fertilizes egg inside female polyp

#2: Egg and sperm bundles are released into water, where fertilization occurs. Corals close to each other tend to do this at the same time in annual spawning events.

Asexual reproduction for coral (4)

Fragmentation: When a piece or tissue from parent colony is dislodged, comes across a good surface, fuses with it, and starts growing own colony.

Polyp bailout: Fragmentation, except it's intentional by the coral itself

Parthenogenesis: Unfertilized egg develops into larva without contact with sperm. Rare

Budding: a single polyp is formed either via the division of an existing polyp (intratentacular budding) or from the space between polyps (extratentacular budding). More for growth, since the new polyp is still part of the parent coral.

What're coral skeletons made of?

Aragonite (type of calcium carbonate)

Zooxanthellae

Have mutualistic relationship to coral (coral gives CO2, water, etc for zooxanthellae photosynthesis, while zooxanthellae provide sugars, proteins, etc via photosynthesis so coral can make CaCO3, make carbs, etc.

Zooxanthellae also provide coral their color.

Phylum that jellyfish, anemone, and coral are in

Cnidaria.

All of them have a type of cell: cnidocytes with stinging “nematocysts” (for catching prey/defending against predators) and radial symmetry (one axis).

1, 2, 3, 4, 5, 6

7, 8, 9, 10, 11, 12

Mangrove forests definition

Function/importance? (5)

Forests of mangrove trees on shorelines in brackish water.

Function:

• Protects against storms/erosion (due to distinct roots that slow tidal waters), and flooding

• Are good sources of food and timber for humans

  • Environment for animals for refuge, food, nurseries, etc.

• improves water quality (roots hold onto sediment, and plant helps use up excess nutrients, preventing HABs)

• carbon sequestration (of e.g. carbon-rich material like leaves) in layers of slow-decaying, fine, O2-poor underwater sediment (can extract up to 5x more carbon than land forests, up to 10x faster; most efficient carbon sink.

Mangrove tree adaptations (4.5)

• Waxy barrier that reduces transpiration & osmosis (aka its moisture from leaving into salty surroundings)

• Taking in salt, then secreting it out again via salt glands on leaves

• Storing salt in the large-volume leaf cells, which results in osmosis/fleshy leaves (e.g. succulence)

• Cable roots with lenticel-having pneumatophores with access to air (instead of taproots)

  • Knee roots that grow vertically into the air, then loop back down into ground.

• Vivipary, where offspring (propagulates) begin to grow while still attached to parent, skipping dormant seed stage. After maturing, detaches, eventually sinking into soil.