–Soft corals that resemble large feathers–May grow from a few cm to well over 2 m in height.
–Found in most reef environments.
•Gorgonians (Sea Fans)–Fan shaped soft coral.
–Branches with delicate lace-like patterns.
–Body is made up of a protein called gorgonin.
–How are they oriented?
–What wave conditions do you expect to find them in?
•Precious Corals (Gold Corals)
–Rare corals that grow in the darkness.
– 1500 feet.
–Strong nutrient rich cold ocean currents sustain them.
–Considered precious and are valued for their hard skeletons which are used for jewelry.
•Black Coral–Uncertainty of the exact classification of Black Corals.
–Include “Black Corals” and “Tube Anemones”.
–Used in jewelry and often confused with gorgonians.
–Can grow up to several meters in height.
•Includes the true anemones (Order Actiniaria) and hard corals (Order Scleractinia).
•Have six or a multiple of six tentacles on their polyps.
•Hard corals are considered “true corals” because of their internal limestone skeleton.
Coral Reefs are built by dense communities of Scleractinian corals of many shapes and sizes
Factors that decrease coral cover and diversity result in ecosystem degradation
What Is A Coral? (5)
•Corals are found in ocean throughout the world’s oceans in polar, temperate, and tropical locations.
•Greatest diversity found in the tropics
•Two types of corals ahermatypic & hermatypic
•Ahermatypic corals do not form reefs
•Hermatypic corals are reef building and only found in tropical locations
Scleractinian Corals (4)
•Phylum Cnidaria, Class Anthozoa, Subclass Hexacorallia, Order Scleractinia
•Primary reef builders since Jurassic Era (200 MYA)
•60 genera and more then 650 species
•Most reef building species have a symbiosis with a group of algae known as zooxanthellae
Biology of Reef Building Scleractinian Corals
•Characteristics–Phylogenetically diverse–Many different growth forms that indicate different habitat requirements, competitive abilities
–Only some of them are hermatypic–Most but not all hermatypic species contain zooxanthellae
–Zooxanthellae impose ecological and physiological constraints on their coral hosts
Zooxanthellae (4) Part 1
•Important to coral’s nutrition and growth.
•Limits corals to shallow marine waters–Why?
•Zooxanthellae enable reef building corals to calcify 4 to 10 times faster than non-symbiotic, non reef building corals.
Importance of Symbiosis to ReefBuilding Scleractinian Corals (3)
• Not all zooxanthellate coralsare hermatypic
• Presence of thezooxanthellae in the coralsstimulates their calcificationand allows for increasedgrowth
• Nutrient cycling betweencorals and zooxanthellaecontributes to higher reefproductivity then might beexpected.
Importance of Symbiosis to ReefBuilding Scleractinian Corals (2)
• The coral-zooxanthellae symbiosis is anutritional advantage for corals.
• Hermatypic corals can still feed like otheranimals.
Zooxanthellae(4) Part 2
• Initially thought to be single species.
• Chang et al, 1983 found physiologicaldifferences between strains under same lightconditions.
• Some coral larvae are released withzooxanthellae.
• Most need to take them up from environmentafter settlement.
Zooxanthellae (4) Part 3
• Research has shown zooxanthellae living in/onreef substrate.
• Zooxanthellae swim towards higherconcentrations of ammonium (Fitt, 1984).
• Problem: Algae grow faster then host coral.
• Possible Solutions?– Expel excess zooxanthellae.– Digest excess algae (Tridacna spp).– Limit growth (nutrient limitation).
Coral Nutrition (4)
• Capture of larger particulateswith tentacles andnematocysts.
• Capture of fine particulatematter with ciliary bands.
• Uptake of dissolved organicmatter such as amino acidsand sugars.
• Translocation ofphotosynthetic products fromzooxanthellae.
Reef Formation (3)
• Rate of CaCO3 production > rate of CaCO3breakdown. Leaves CaCO3 left over for reefformation.
• Physical conditions must allow that excesscarbonate accumulates in one place.
• Present day “coral reefs” may be thin veneer ofcoral growing on reef structures produced bycoral communities thousands of years ago andthere may be little to no reef-building takingplace today.
Coral Reef Facts (3)
• Coral reefs are oldest, most productive anddiverse ecosystems in the sea.
• Coral reefs are the largest structures made byliving organisms on earth.
• Coral reefs occupy less than one percent ofocean floors but are home to nearly 25% ofmarine species.
Coral Reef Geomorphology (3)
• Fore reef slopes seaward: 1-30m deep.
• Reef crest/flat: berms & islands; 1-2 m deep.
• Backreef: lagoon and patch reefs, 2-10 m deep.
Coral Reef Geomorphology (2)
• What are the three reef types?
• Development of the different reef zonesdepends on:– Depth and shape of ground that the reef formed.– Amount of wave and storm energy.
Reef Evolution Theories
Reefs in different parts of the world developed in different ways depending on how tectonic forces, glacial periods and temperature changes affected their development.
Difference Between Atlantic andIndo-Pacific Reefs (4) Part 1
• Atlantic has 40 genera and 70species of coral, and around500 species of fishes.
• Indo-Pacific has more then 80genera and 700 species ofcorals, and more then 4,000species of fishes.
• Of the 107 genera of coral,Atlantic and Pacific share only8.
• Sea fans and whips are muchmore common in Atlantic thenin the Indo-Pacific.
Difference Between Atlantic andIndo-Pacific Reefs (3) Part 2
• Indo-Pacific reefs have a large number of soft(alcyonarian) corals
• Pacific reefs are typically categorized as atolls,barrier reefs, and fringing reefs
• Atlantic reefs are often described as bankbarrier
Limiting Factors (6)
• Temperature– 25-29oC
• Depth– Most grow at 25m or less.
• Substrate– Settling corals require bare consolidated substrate.
• Salinity– Normal sea water (32-36 ppt).
• Wave Action
• Loya (1972) early study of zonation anddiversity.
– Coral species diversity increases (then decreaseswith depth; therefore no correlation with lightattenuation
– Colony size larger at intermediate depths
– Colony size decreases down slope
– Steeper slopes have higher cover and diversity
• less sediment stress
Reef Zonation Part 2
Zonation is most pronounced on very exposedwindward reefs and least on sheltered, leeward reefs.
Reef Zonation Part 3
• Wave affected areas:
– Wave resistant branched forms.
– Thickened branches that channel water.– Encrusting and streamlined growth forms.
• Sheltered areas:
– More diverse growth forms adapted to removesediment.
– Delicate branches.
– Large massive colonies.
– Flattened colonies with depth in response to low light.
Community Interactions (4)
• For corals reefs to form, reef corals must be ableto dominate the benthic community, but algaeare needed to provide food for reef organisms.
• Nutrient levels are generally low, and reef algaeare low nutrient adapted.
• High levels of herbivory protect corals fromalgae, and pass the algal energy up the trophiclevels.
• Increases in nutrients tip the balance towardsalgal dominance
Mature reefs have high architectural complexity that provides habitat and increased surface are for primary producers.
•In coral reef ecosystems large schools of herbivores are common unlike most other marine ecosystems.
Community Interactions (2)
•Corals with resident fishes grow faster then those without.
•Fertilizer!!–Meyer and Schultz (1983) found that excretion and fecal productions from fishes and inverts are important to nutrient recycling.
Community Structure Part 2
•What factors allow coral dominance and prevent species from out
-competing and dominating others?
–Predation (prevents competitive dominance: competitive networks)
–Disturbance (renews succession)
–Symbioses of various kinds–Special adaptations (e.g. feeding deterrents; colonial growth forms)
Community Structure (3)
•Corals must compete against many plants and animals when attempting to settle on the reef substrate
•Competition for substrate is high (especially on well lit surfaces)
•Algae are primary competition.
Competition For Space
•Several different kinds of algae are the fastest growing competitors for substrate.
–Crustose coralline algae; easily overgrown by other forms of algae when grazing levels are low.
– Forest of small filaments of a number of species,generally < 1cm high; usually the result of heavy grazing
Reef Algae Part 2
• Macro algae
– Larger plants of green, red, and brown types.
Reef Algae (2)
• Blue Green Algae
– Cyanobacterialmats, some nitrogenfixing.
Reef Algae (3)
– Diatom mats on sediment.
– Benthic dinoflagellates asepiphytes and on rocks.
Impacts on Corals
•Increased water temperature results in coral bleaching.
–Expulsion of zooxanthelae from by the coral polyps.
•Relatively new to coral reefs.
–Poor water quality a possibility.
Diadema Die Off (2) Part 1
•Diadema antillarum one of the most important/effective herbivore on coral reefs leading up to 1983.
•Unknown cause of mass die off during 1983. After die off Caribbean corals reefs became over-grown with algae.
Diadema Die Off
•Now when corals die they are replaced by algae.
•Lack of herbivores make it impossible for corals to recover from storm damage, disease, predation etc.
• When ratio of % algal cover to grazing pressureincreases algal species shift towards calcified orchemically defended algae
• When Diadema are returning algal cover isdecreasing.
Diadema Return Part 2
• Where Diadema have returned abundance ofcoral recruits appears to be increasing
Deep Sea Biology
• Defined: Areas within the ocean that lie below thelevel of effective light penetration (>200 m).
• Disphotic Zone: Upper deepwater zone, receivessome light.
• Aphotic Zone: Area below dysphotic that receives nolight.
• Mesopelagic: Disphotic Zone
– Fish are generally black or red
– Most well studied
– Most biomass of deepwater zones
Zonation Part 3
• Bathypelagic/Abyssalpelagic: Aphotic Zone
– Organisms generally white/colorless
– Low biomass
– Bioluminescence for food attraction
Zonation Part 3
• Hadalpelagic: Aphotic Zone
– Trench areas
– Virtually unstudied
•Incredible depths–5-6 kilometers of cable needed to trawl at 4,000 m
•Large amounts of cable make it impossible to determine effectiveness–Increases likelihood of failure
–Most dredges sample an unknown area
–Large slow moving net
–Photosynthesis not possible
–Only light from animals themselves
–Animals must rely on other senses
Environmental Characteristics Part 2
–Increases 1 atm every 10 m
•Deep Sea is under pressures of 200-600 atm
–Organisms previously impossible to study (DOA)
–Significantly effects biology of deep sea creatures
•Proteins and membranes modified to work at pressure
•Muscle enzymes less efficient in deep-dwelling fishes
•Alters morphology of cells
•Solubility of calcium carbonate decreases with pressure
Environmental Characteristics Part 4
•Salinity remains stable in the deep sea
–Oxygen rich cold waters sink to deep ocean
–Increases due to low biomass and low metabolic rates
–Decreases 20 m above bottom of the ocean
Food Part 1
–Food mostly comes from above
•Amount of food correlated with primary production at surface
•Probability a particle will decay or be consumed increases with depth
Food Part 2
–Deep sea organisms themselves
•Unpredictable but reliable
•Animals have evolved to live on whale/shark remains
•Mesopelagic Fish: Silvery gray or black–Not countershaded
•Mesopelagic Inverts: Purple, Red, or Orange–Why red colors?
•Abyssal/Bathyal Fish: Generally black
•Abyssal/Bathyal Inverts: Colorless or dirty white
–Some colorful i.e. Anemone
•Large eyes in mesopelagic and upper bathypelagic.
–Generally larger eyes than those in photic zone.
–Eyes are also enhanced with pigment and increased density of rods
•Abyssalpelagic/Hadalpelagic show opposite trend–Eyes reduced or lost completely
–Unique tube shaped eyes with two retinas
•One at the base, one on the wall
–Allow for binocular vision
•Light flashes seen by both eyes
•Some squid have evolved dimorphic eyes
–Larger looks up, smaller looks down
•Food scarcity has resulted in food related adaptations
•Large mouths–Long teeth curved towards throat
–Mouth and skull hinged for wide opening.
•Lures–Modified dorsal fin
–Attached to barbels
•Black lined coeloms
•Difficult to find a mate in the deep sea.
•Use bioluminescence to identify one another.
•Some give off chemical scents or pheromones.
•Many are hermaphroditic and some are even parasitic.
–Lack of food should result in smaller size
•Many fish show this relationship
•Very few large fishes–Abyssal gigantism
•38 cm isopod
•15 cm amphipod
•10 mm copepod
–Results of pressure on metabolism
–Low temperature/food results in reduced growth rates.
•Delays sexual maturity
•Results in larger individuals
•Benthic habitat is made up of soft ooze
–Bottom dwelling organisms tend to have:
–100 times less than in shallow water
•Slower metabolic activity
–Increased depth results in increased water content
–Protein content decreases with depth
•Production of light by living organisms
–Identical to method used by fireflies
–Color varies from species to species
•460-480 nm in mesopelagic species
–Light producing organs found primarily in fishes and squid
–Mesopelagic and upper bathylpelagic
•Decreases in deepest ocean
–Range in complexity
•Simple light production
•Ability to move photophores, alter color, focus using lenses, etc..
Benthic Taxonomic Diversity
•Epifauna vs. Infauna
–Polychaete Worms: 40-80%
–Sea Cucumbers and Brittle Stars also common
•Suspension feeders rare
•Carnivore numbers uncertain
•Majority of organisms are deposit feeders (~80%)
•Deep ocean originally thought to be a biological desert
–Increased sampling efforts
–Improved dredging and sampling processing
•Replaced by opposite thought
–Deep sea diversity = coral reef diversity
–Diversity increases over time
–Stable conditions allow for specialization
•Cropper Theory–Increased competition for food prevents the build up of any particular species
–Species number positively correlated with area
Life History Patterns
•Low metabolic rate slows or delays reproduction
•Information on reproductive cycles unknown
•Planktotrophic and pelagic stages common
•Two reproductive patterns:
–Early stages of life spent in lighted areas follow by migration to deeper waters
–No migration occurs
Life History Patterns
–May brood eggs for 400 days
–Young reside at greater depths than parents
•1977 scientists off the coast of Galapagos discovered first hydrothermal vents.
–Water temperature 8-16⁰ C above normal–Rich in sulfur compounds (H2S )
•Hydrogen Sulfide major energy source
–Found at depths ranging from 1500
-3200 m–Found along tectonic plates
–Similar chemoautotrophic communities found in other areas
–Original hydrothermal vents
•Primarily Iron and Sulfide
–Similar to black smokers
•Barium, Calcium, and Silicon
–Slow seeping of nutrients
–Hydrogen Sulfide or Methane
Living on a DSV
•All vents depend on primary productivity of chemolithoautotrophic bacteria
•Sulfide rapidly dispersed in seawater
–Communities have small area where O2 and S2 are ideal.
•Extremely high productivity
•Conditions unsuitable for life
–Most organisms live in areas:
•Below 30⁰ C
•Under 400 μm of hydrogen sulfide
•Riftia pachyptila and Calyptogena magnifica are two examples of animals that are involved in symbiosis.
–Contain chemosynthetic bacteria
–Receive nutrition from the bacteria
–Use a protein factor to transport normally toxic sulfide to the bacteria
•Bathymodiolus thrive in cold seeps and have a methane based symbiosis
–Methane take in through gills
–Bacteria oxidize the methane
•Gives energy to mussels and bacteria
•1) Export production of bacteria
•2) Suspension Feeding
•4) Symbiotic Relationships
Who lives here?
–Vent endemic eelpout
Vent Life History
–Weeks to years
–Unexpected lava flows/Chimney Falls
•Implies short life for vent organisms
–Lack planktonic stage
–High mortality among tube worms
•44% in 26 days
•Ecology generally unknown
•Migration–Lack of observations
Deep Scattering Layer
•Development of sonar in WW2 lead to discovery of random echoes
–Hundreds/Thousands of meters above bottom
•Deep scattering layers
–Appeared to shift upward at night
•Discovered to be concentrations of midwater animals
–Movement is vertical migration
•Pelagic zone dominated by small fishes and crustaceans
•Primarily Copepods–Ontological/Seasonal Shifts–True generalists rare
Mesopelagic Life History
•Sexually Mature 1-3 years
•1-4 year life span
•Juveniles do not migrate–Crustaceans
•Mature 1-2 years
•1-3 year life span
•Seasonal and continuous examples