© H. Moody

Found on “healthy” coral reefs

stony coralscrustose coralline

algaereef

fishes

stony corals

sparse turf algae

AGRRA: Introduction to Coral Reefs

Revision: 2012-03-09 Judith Lang

The following images are Copyright ©by New World Publications

and by other photographers. Permission is granted to use the photographs and slides in this presentation with the AGRRA

Program and, with attribution, for other valid educational purposes.

All other uses are strictly prohibited.

For permission to use their images, special thanks to: L. Benvenuti, A. Bruckner, J. Bruno, K. Desai, P. Dustan,

P. Edmunds, M. Gerber, E. Hickerson, H. Hudson, P. Humann, L. Ilyes, B. Kakuk, J.-P. Maréchal, K. Marks, R. McCall, M. Moe, H. Moody, A. Moulding, M. Nugues, J. Reichman, C. Rogers, A. St. Gelais,

G. Schmahl, R. Steneck, C. van Dongen, E. Weil, L. Williams

Stony corals are the major framework constructors of coral reefs. Their soft polyps overlie stony (calcareous) skeletons.

Meandrina jacksoni© R. McCall

The polyps expand to feed on plankton, usually at night.

Colonies are formed when the polyps divide asexually.

Diagram from P. Humann

Tentacle Mouth

Single Polyp

Skeleton

Colony

Colonial corals continue to grow via asexual division (reproduction) throughout their lives.

Porites porites and Millepora complanata

© K. Desai

Adult corals also reproduce sexually. Species that grow large engage in mass spawning of gametes once, or several times, a year.

© E. Hickerson

Montastraea franksi Colpophyllia natans

Close-up

© G. Schmahl

Recruits give reefs a chance of recovering after disasters have killed adult corals.

Coral larvae need to settle on solid surfaces like dead corals or crustose coralline algae.

Porites astreoides

polyp

larvae

recruit juvenile

© R. Steneck

© A. St. Gelais

© A. St. Gelais© A. Moulding

Zooxanthellae (‘zoox’) are tiny, yellow-brown algae in some cells of reef-building corals.

Zoox gain shelter, access to carbon dioxide for photosynthesis and inorganic wastes (= nutrients for growth) from their host coral.

Close-up

© J. Reichman

© A. Moulding

Zoox contribute organic compounds to their coral host (= support its health, growth, and calcification).

Montastraea cavernosa recruit with zoox

Clades are genetically distinct populatons of zoox that characterize certain reef habitats, and/or coral species and/or location on a coral.

Bleached corals are still alive!

Bleaching occurs when most of the zoox are gone, and/or remain but have lost most of their yellow-brown photosynthetic pigments.

Corals are not killed by temporary bleaching.

© L. Benvenuti

Close-up

Bleached Porites

Bleaching occurs in response to unusually high or low temperatures, unusually high or low salinities, or too much sediment.

Partially bleached Montastraea annularis

© C. Rogers

Severity of bleaching varies by:• the coral’s species or colony identity • the cladal identity of its zoox • its location on the reef with respect to depth, currents, shading, etc.

C. natans D. labyrinthiformis

completely bleached

notbleached

© L. Williams

M. meandrites© K. Marks

partially bleached

When mass bleaching occurs, sea water temperature is above warm season averages.* Polyps die and/or, at least temporarily, are more susceptible to disease and/or their future growth or sexual reproduction is reduced.

© L. Benvenuti

Montastraea faveolata

* Increases of ~1o C for ~4 weeks, or ~3-4o C for 1-2 days

St. John U.S.V.I.

2005

Montastraea annularis

Major Mass Bleaching Events 1998: Bahamas and Mesoamerica 2005: Eastern and NE Caribbean

© C. Rogers

Corals are also killed by pathogens (biological disease causing agents).

Montastraea faveolata with Yellow Band disease (YB)© E. Weil

YB

Large outbreaks of disease are common when corals start to “recover” from severe bleaching.

Formerly bleached Montastraea faveolata now with White Plague (WP)

© J.-P. Maréchal

WP

Corallivores (coral predators) include some invertebrates (below) and fishes.

Snail feeding on a staghorn coral,

Acropora cervicornis

Close-up

Fireworm on a Montastraea faveolata already infected with

White Plague (WP)

WP© A. Bruckner © J. Lang

Threespot damselfish, Stegastes planifrons

© P. Humann

Damselfish like the threespot (Stegastes planifrons) create small lesions in live corals to cultivate algal gardens for food and to use as a nursery for their young.

Montastraea annularis with threespot bites

© B. Kakuk

Stoplight (Sparisoma viride) and some other parrotfishes kill coral polyps and excavate their skeletons.

Stoplight parrotfish (S. viride) biting Montastraea annularis

© A. Bruckner

Lesions from merged stoplight bites can be > 30 cm/12 in long!

© A. Bruckner

Partial Mortality: when parts of a coral die, the white skeleton below is exposed, superficially resembling bleaching.

© P. Dustan

Close-up

white skeleton = new mortality

Mycetophyllia with new mortality

When large predators are rare, corallivores may be very common and kill many corals.

© R. Steneck

Black grouper, Mycteroperca bonaci

aggressive invertebrates

© B. Kakukmacroalgae

cyano-bacteria

© B. Kakuk

(thick/dense) turf algae

© J. Lang © P. Edmunds

Corals may lose when competing for space on the substratum with cyanobacteria, thick/dense turf algae, macroalgae, and some invertebrates.

Feeding by Diadema antillarum (long-spined sea urchin) and large (≥ 30 cm) parrotfishes dislodges the basal holdfasts of benthic algae.

Stoplight parrotfish, Sparisoma viride

© R. Steneck

Having been decimated by disease, Diadema are now rare on many reefs.

© M. Moe

When large herbivores are rare, turf algae and macroalgae (seaweeds) may colonize dead corals, becoming so abundant that they prevent coral larvae from settling. These algae can also overgrow live corals.

© J. Bruno

Overfishing in the wider Caribbean has already depleted many populations of shark, large- and small-sized bony fish, queen conch and spiny lobster.

© J. Bruno © C. van Dongen

Rapidly assess key structural and functional attributes of tropical Western Atlantic reefs.

Benthic Algae

Carnivores

© B. Kakuk

© R. Steneck

And provide fishery- independent estimates of fishing intensity.

AGRRA Program Primary Goals:

Stony Corals

© R. Steneck

© L. Benvenuti

© M. Moe

Herbivores

S. siderea

encrusting/nodular

M. decactis

© P. Humann

platy/bifacial© R. Steneck

M. complanata

© M. Nugues

U. agaricites

Common AGRRA Coralsby shape and size

flower (phaceloid)

E. fastigiata

© R. Steneck

A. palmata P. porites

© C. Rogers

branchingmassive

M. faveolata

P. astreoides

S. siderea

© R. Steneck

© R. Steneck

turf algae

AGRRA Benthic Algal Groups

© K. Marks

macroalgaecyanobacteria© H. Hudson

Close-up

© J. Lang

crustose coralline algae© K. Marks

© L. Ilyes

Common AGRRA Fish Groups

ornamentals

angelfish

© R. Steneck

butterflyfish

© P. Humann

© C. Rogers

herbivores

damselfish© P. Humann

parrotfish

© L. Ilyes

predators

© R. Steneck © P. Humann

© M. Gerber

grouper

snapper

gruntsurgeonfish