Competitive Interactions on a Reef

Kinds of Competition between Corals Connell (‘73) Contact and interaction between soft tissues of coral No contact between coral colonies Direct CompetitionIndirect Competition

Kinds of Competition between Corals Direct Competition 1. Mesenterial Filaments

Kinds of Competition between Corals Direct Competition 1. Mesenterial Filaments FaviidaeMeandrinidaeMussidae

Kinds of Competition between Corals Direct Competition 2. Sweeper Tentacles

Kinds of Competition between Corals Direct Competition 3. Sweeper Polyps (Goniopora)

Kinds of Competition between Corals Direct Competition 4. Mucous Secretion (Fungia)

Kinds of Competition between Corals Direct Competition 5. Histoincompatibility

Kinds of Competition between Corals Direct Competition 6. Overgrowth

Kinds of Competition between Corals Indirect Competition 1. Overtopping

Mechanisms for Algal Effects on Corals Microalgae Filamentous Foliose Crustose Calcareous Branching Digitate Tabulate Encrusting Massive Mushroom O, C O, C O, C O, C O, C - O, O, O, O, O, - O, - - O, O, - O, Macrophytes S, C S, C S, C S, A S, A - O = OVERGROWTH, C = CHEMICAL, S = SHADING, A = ABRASION

Competition and New Recruits Vermeij, ‘06

Competition and New Recruits Vermeij, ‘06 3 m

Competition and New Recruits Vermeij, ‘06 Available space Time

Competition and New Recruits Vermeij, ‘06 Overgrowth Crustose corallines Sponges Macroalgae Sponges Crustose corallines Ascidians

Competition and New Recruits Vermeij, ‘06 Unoccupied Coralline algae Macroalgae Sponges % Cover % Cover Time

Competition and New Recruits Vermeij, ‘ % Mortality

Competition and New Recruits Vermeij, ‘06 Coral Recruits - Had 16 species recruit – 4 did well - Most successful corals – Agaricia, Montastrea, Tubastrea - Most successful corals – brooders - Most successful corals – shallower panels

Competition and New Recruits Vermeij, ‘06 Greatest contributors to recruit mortality 1. Sponges 2. Bivalves

Competition among Cryptic Metazoa

Jackson (‘92) - artificial substrates % Cover Time Free space Colonials Solitary

Competition among Cryptic Metazoa Jackson (‘92) - artificial substrates Abundance Time % suspended cells retained Sponges Bryozoans

Competition among Reef Fish Munday et al, 2001 Lizard Island

Competition among Reef Fish Munday et al, 2001 Gobiodon axillaris Gobiodon unicolor Gobiodon rivulatus Gobiodon brochus Gobiodon histrio Gobiodon quinquestrigiatus

Competition among Reef Fish Gobiodon axillaris Gobiodon unicolor Gobiodon rivulatus Gobiodon brochus Gobiodon histrio Gobiodon quinquestrigiatus 5 cm

Competition among Reef Fish Munday et al, 2001 Acropora gemmifera Acropora nasuta Commonly usedOccasionally used

Competition among Reef Fish

Munday et al, 2001 Gobiodon axillaris Gobiodon unicolor Gobiodon rivulatus Gobiodon brochus G. histrioG. q. Habitat Use - % Overlap G.axillarisG. brochusG. rivulatus G. quinquestrigiatus

Competition among Reef Fish Acropora nasuta Acropora gemmifera HABITAT CHOICE

Competition among Reef Fish Munday et al, 2002 Acropora nasuta Acropora gemmifera ??? HABITAT CHOICE

Competition among Reef Fish Munday et al, 2002 Gobiodon axillaris Gobiodon unicolor Gobiodon rivulatus Gobiodon brochus G. histrio G. quinquestrigatus Acropora nasutaAcropora gemmifera

Competition among Reef Fish Munday et al, 2002 Gobiodon axillaris Gobiodon unicolor Gobiodon rivulatus Gobiodon brochus G. histrio G. quinquestrigatus CACP * ** * HABITAT CHOICE EFFECT OF COMPETITOR

Gobiodon axillaris Gobiodon histrio HABITAT CHOICE EFFECT OF SIZE AND PRIOR RESIDENCE No prior resident G axillaris prior resident A < H A = H A > H A < H A = H A > H WINLOSEDRAW Outcome for G. axillaris

Gobiodon histrio HABITAT CHOICE EFFECT OF SIZE AND PRIOR RESIDENCE No prior resident G. brochus prior resident B < H B = H B > H B < H B = H B > H WINLOSEDRAW Outcome for G. brochus Gobiodon brochus

REMOVAL AND RECOLONIZATION Gobiodon axillaris Gobiodon unicolor Gobiodon rivulatus Gobiodon brochus G. histrio G. quinquestrigatus Removal Control Removal of G. histrio Increase in abundanceDecrease

REMOVAL AND RECOLONIZATION G. axillaris G. unicolorG. rivulatus G. brochusG. histrioG. quinquestrigatus G. histrio G. axillaris G. quinquestrigatus Proportion of fish recolonizing

Competition among Reef Fish CONCLUSIONS 1. G. axillaris and G. brochus compete with G. histrio for space (removal of G. histrio leads to increases in the other two) 2. Other species do not compete with G. histrio for space (even though there can be high overlap – e.g. G. quinquestrigatus) Argues for different methods of coexistence

Competition among Reef Fish CONCLUSIONS 3. G. axillaris and G. histrio coexist in experimental plots (G. axillaris – reef flat, G. histrio – reef crest) 4. Colonies of A. nasuta that were occupied by G. quinquestrigatus are recolonized by G. quinquestrigatus but not colonies of A. nasuta occupied by other species. (G. quinquestrigatus uses different component of A. nasuta population)

Coral – Algal Competition (Jompa and McCook, 2002) Lobophora variegataPorites cylindrica

Coral – Algal Competition (Jompa and McCook, 2002) 1. Herbivory Experimental Design Full Cage No Cage Partial Cage 2. CompetitorAlgal removal Control Coral damage Measured growth and mortality of P. cylindrica and L. variegatus

Coral – Algal Competition (Jompa and McCook, 2002) Tissue mortality (P. cylindrica) Open Full Partial Highest mortality where herbivores are excluded Alga present Alga absent

Coral – Algal Competition (Jompa and McCook, 2002) Skeletal extension (P. cylindrica) Open Full Partial Highest growth when algae are absent Alga present Alga absent

Coral – Algal Competition (Jompa and McCook, 2002) Growth (L. variegata) Open Full Partial Highest growth when corals are damaged Coral present Coral absent