Marine Biology Exam 3

Rocky Intertidal

What are the rocky intertidal zones

Spray zone, Upper (high) intertidal, middle intertidal, lower intertidal

what is the spray zone

Located above the high tide line and wetted by splash and spray and occasionally by extremely high tides or storms

what is the upper (high) intertidal zone

Submerged during the high tide, but exposed and dry for long periods between the high tides.

what is the middle intertidal zone

Submerged and exposed whaby the tides on a regular basis

what is lower intertidal

Submerged most of the time. Only exposed during the lowest Spring tides.

what is vertical zonation

systematic horizontal layering of organisms into bands along a vertical gradient

What physical factors affect vertical zonation

1. Desiccation

2. thermal stress

3. changes in salinity

4. shortage of oxygen

5. reduced opportunities for feeding

6. wave shock

What organisms are in upper rocky intertidal

1. periwinkles - dominant

2. limpets

3. lichens

4. encrusting algae

what organisms are in middle intertidal

1. barnacles - dominant

2. mussels

3. seaweeds

what organisms are in lower intertidal /extreme lower

1. lower → irish moss

2. seaweeds

what are upper limits of species distributions

1. desiccation (drying up and dying from lack of moisture, instense sun or freezing winter)

2. Restriction of feeding (ex barnacles mussels) (filter feeders unable to feed when tide is out / even mobile feeders at risk of drying out when active

adaptations for upper limits of distribution

1. color → brown shell reflects solar radiation better than black / white shell reflect sunlight

2. stay cool → shell ridges radiate heat

3. high wave energy resistance → grow shorter so theres less resistance pushing from wave / flexibility allows them to flow in high current and not break

what biological factors affect zonation

1. larval and adult preference

2. competition

3. feeding/ predation

lower distributions limits

1. competition → space is a limiting facts / species can overgrow or undercut other species and dominate a level / impacts size of species realized niche

2. feeding and predation → predators limited by immersion time / ex: mussel beds sharp lower limit because of carnivorous sea stars

what is a keystone species

organism that holds together ecosystem and required for stability due to their large influence. removal often leads to reduced biodiversity or ecosystem collapse

Rocky intertidal keystone species

sea stars

Subtidal Hard bottom environments (seaweeds and kelp forests)

characteristics of seaweeds (macroalgae)

1. eukaryotic

2. multicellular

3. photosynthetic

4. typically grow attached to substrate

5. lack true roots &vascular systems & absorb nutrients directly from water

6. many produce distasteful chemicals to deter grazing

Anatomy

Thallus : can vary from tar like crust to elaborate branching with differentiated structures for light gathering, support, reproduction, flotation, and attachment

usually a holdfast, stipe, and blade(or frond)

Blades and Pneumatocysts

Stipes & Holdfasts

• holdfasts attach macro algae to the substrate

• stipes provide support and connect the blades and holdfast (in some groups stipe is well developed / others the blades merge into holdfast without stipe)

asexual reproduction

vegetative growth

sexualreproduction

• larger seweeds alternate between sporophytes and gametophytes

• prominence of these generations vary among species

• red algae commonly have 3 distinct life cycle stages

how are seaweeds classified

1. pigments used to gather light for photosynthesis

2. storage products

3. types of flagella in spores

green algae characteristics (features, pigments, food reserves, cell wall components, ecology)

1. eukaryotic protists, unicellular and multicellular, mostly bottom dwelling, many have alteration of generation

2. pigments: chlorophyll a, b, carotenoids

3. food reserves: starch

4. cell wall components: cellulose, calcium carbonate in calcareous algae

5. ecology: primary producers, calcareous → important for reefs

red algae (rhodophyta) characteristics (features, pigments, food reserves, cell wall components, ecology)

1. features: eukaryotic protists, multicellular, bottom dwelling, alteration 3 generations

2. pigments: chlorophyll a, phycobilins

3. food reserve: starch

4. cell wall: agar, carrageenan, cellulose, calcium in coralline

5. ecology: primary producers, coralline important for reefs

Brown seaweeds (Phaeophyta) characteristics (features, pigments, food reserves, cell wall components, ecology)

1. features: eukaryotic protists, multicellular, bottomdwelling, some alteration of generations

2. pigments: chlorophyll a,c, carotenoids

3. food reserves: laminarin, alginates

4. cell wall: cellulose, alginates

5. ecology: primary producers, dominate kelp forests

kelp forces’s influenced by

1. temperature

2. light levels

3. substrate

4. wave energy

kelp forest food web

how do sea urchins affect kelp forests

1. sedentary behavior feed primarily on drift kelp

2. active feeding behavior large numbers strip away kelps/ seaweeds leaving urchin barrens

kelp forests key stone species

sea otters (if orcas eat too many → urchins overgraze and kill kelp)

soft bottom communities and estuaries

how does grain size affect type of organisms found (large/fine)

larger grain: provide site for attachment so epifauna and flora dominate

finer grain: often unstable / most organisms are infauna and meiofauna

intermediate grain: inhospitable because too unstable for epifauna but too large for infaunal

grain size relationship to porosity and permeability

A. well sorted (coarse) → water drains quickly

B. well sorted (fine) → water drains slowly

C. poorly sorted → water blocked

how does grain size affect oxygen availability and organic matter

1. Fine sediments → higher amounts of organic matter and reduced water flow → deficient in oxygen

2. Coarse sediments → lower amounts of organic material and greater water flow → more abundant oxygen

Size classifications

1. macrobenthos > 0.5mm

2. Meibenthos 0.1 - 0.5mm

3. microbenthos < 0.1mm

epibenthic / epifaunal

lives on top of seafloor attatched to surfaces

infaunal

lives buried within sediment

semi-infaunal

partially buried, part of body insediment, part exposed

interstitial

lives between sediment grains (tiny spaces in sand or mud)

demersal

lives just above seafloor, swims but stays near bottom

food web of soft bottoms

types of feeding

1. deposit feeding: eats organic material in sediment (swallows sand/ mud and extracts food)

2. suspension feeding: filters food particles from water (uses water currents to capture food)

what is an estuary

coastal area where freshwater from rivers mixes with saltwater from the ocean (usually partially enclosed)

what are the types of estuaries

1. tectonic: formed when land sinks or faults → sea water floods in

2. fjord / glacier carved : deep steep sided valleys carved by glaciers → flooded by ocean

3. drowned river valley/ coastal plain: river valleys flooded by rising sea level (broad and gentle sloping

4. bar built /restricted mouth: sand bars or barrier islands partially block the estuary from the ocean

circulation patterns in estuaries

freshwater flows out at surface and denser salt water flows along bottom → mixing and salinity gradient

1. salt wedge

2. partially mixed

3. well mixed

4. fjord type

estuary communities

1. open water in bays, channels, and tidal creeks: (plankton, floating algae, fish, larvae

2. mudflats: (snails, clams, worms shrimp, birds are major predators)

3. salt marshes

4. mangrove forests

5. oyster reefs

6. seagrass beds

salt marshes

where are salt marshes found

mid to high latitudes

what are the ecosystem services of salt marshes

1. coastal protection: reduce storm impact/ flooding, stabilize sediments and reduce erosion

2. habitat: nursery and nesting ground, foraging grounds, shelter

3. carbon storage: sequester more carbon than terrestrial forests

4. clean water: filter pollutants and runoff

salt marsh structure

what are the challenging conditions in the salt marsh

1. waterlogged

2. anoxic sediments

3. high salt levels

what are salt adaptations

most are halophytes (salt tolerant plants)

1. salt glands (excrete excess salt)

2. succulence + concentrating salt into vacuoles in leaves that will be dropped

3. salt exclusion (filters out salt at the roots)

what are adaptations to anoxic sediments

1. aerenchyma tissue: spongy tissue helps oxygen move to submerged roots

2. adventitious roots: roots that grow from stems or above ground parts to help support and uptake oxygen

what is the dominant species in salt marsh and what does it do

Spartina: smooth cordgrass (acts as ecosystem engineer by trapping sediments, stabilizing shoreline & reduce erosion, build marsh elevation, create habitat, slow water flow increasing nutrient retention)

what is the georgia salt marsh zonation

1. tidal creek

2. levee

3. low marsh

4. high marsh

5. marsh border

6. transition communities

7. maritime climax forest

what is a levee

tidal creek banks / water aerated / less temp and salinity fluctuation / flow of nutrients/ tall form spartina

low marsh

majority of southern marshland / flooded several hours a day / more variable temp salinity/ short form spartina

high marsh

higher elevation/ flood tides barely enough cover surface for hour / high evaporation and salty / dwarf spartina if present at all

what factors are affecting salt marshes

1. salt pans: small high salt patches limit plant growth

2. thermal stress: extreme heat or cold damage plants

3. wrack: accumulated seaweed, debris, drift material that smothers vegetation

4. consumer pressure: grazing/ burrowing by animals reduce plant cover & alter structure

5. ice: freezing damages plants

what is detritus

dead plant & animal material that decomposes releasing nutrients at the base of the food web (feeds microbes, invertebrates, fish)

helps build soil and organic matter

flow of energy in a salt marsh

sun→ spartina and algae → insect herbivores & detritus → spiders & bacteria, nematodes and crabs, export by tide

threats to salt marshes

1. climate change

2. sea level rise

3. pollution

4. human activity

sea grass beds

how are sea grass beds ecosystem engineers

1. stabilize sediments protect against erosion

2. reduce wave action and currents

3. reduce turbidity and allow sediments to settle out

4. provide habitat for diverse groups of invertebrates and fish

5. nursery grounds

6. primary producers

7. carbon storage and oxygen production

sea grass food web

threats to seagrass communities

1. disease (ex wasting disease)

2. runoff (excess nutrients and pollution)

3. decreasing water clarity

4. dredging and sedimentation

5. prop scarring

mangrove forests

where are mangrove forests located

tropical and subtropical coastal areas

grow in intertidal zones along sheltered shores, estuaries, and lagoons

mangrove adaptations to salinity

1. salt exclusion: ultrafiltration

2. salt glands: excretion

3. accumulation of salt in leaves that are shed

mangrove adaptations to low oxygen

1. red mangrove prop roots: roots above water to access oxygen

2. black mangrove pneumatophores: roots stick out of sediment to absorb oxygen

ecosystem services of mangroves

1. stabilize sediments protect shorelines

2. capture nutrient runoff and improve water quality protecting reefs

3. productive communities

4. nursery habitat for commercially and recreationally important species

5. food, shelter, and habitat for animals in water and canopy

types of florida mangrove

1. red mangrove

2. black mangrove

3. white mangrove

threats to mangroves

1. land clearing for coastal development

2. increased erosion from agricultural grazing

3. sewage and aquaculture outflow add concentrated nitrogen and phosphorus

4. sea level rise changes where they can grow