BIO 475 Lecture 20: Ecology of Reef Fishes
Diversity 10/3/17
● ~4000 Species in Indo-Pacific
● ~1500 species in Caribbean
● ~120 in Bermuda
● Size Range
○ <3cm for gobies and filefishes
○ >2 m for the goliath and queensland's groupers
● Great variety of morphological specializations which often result in unique lifestyles (ex.
Grazing herbivores
● Taxonomy - Class: Osteichthyes (bony fish)
○ Acanthuridae - surgeonfishes
○ Chaetodnitdae- butterflyfishes
○ Labridae- Wrasses
○ Pomacentridae - Damselfishes
○ Scaridae - parrotfishes
○ Pomacanthidae- angelfishes
○ Traits: Breath through gills, cold blooded , any kind of
heterotroph(omnivore,herbivore,carnivore), largest species: mola mola
● Ecological characteristics
○ A wide variety of reproductive and social strategies
○ A bipartite life cycles
■ Dispersive reproductive stage and more sedentary adult stages
● Live in same reef
■ Means a theoretical open system
■ Often highly visual reproductive requiring clear water for feeding and
reproductive
■ Morphological variability and niche diversification lead to co-occurring
guilds of ecologically similar taxa
■ Generally long-long lived , otoliths reveal that
● Serranidae can live 100+ years
● Smaller reef species can live been 12 and 45 years
● Biogeography
○ Diversity is related to ocean age
○ There are a # of reef fish families that occur in the Indo-PAcific but not the
carribean
○ Families occurring in both areas are generally more speciose in the Indo-Pacific,
frequently with a great number of genera as well
○ Species composition gradients are evident across the Pacific, less apparent in
the caribbean
○ Total number of species and species per family decreases
■ Away from centers of diversity
● Tethys sea; now indo pacific triangle
■ From low to high latitudes
● Intermediate Scale
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○ There are strong reefal scale distribution patterns for species and guilds
○ Many species have highly localized patterns of movement and association with
specific zones and structural features of the reef
● Reef-scale distribution patterns are also influenced by cross-shelf characteristics such
as nutrient availability/ effects on production , depth and light penetration
● Microhabitat scale
○ Settling larvae of different species respond to specific habitat cues
○ Many smaller species are highly territorial , with specific microhabitat
requirements
○ Example, 8 damselfish species are each associated with specific sites in West
Indies
● Temporal Distribution Patterns
○ Diel activity patterns
■ Reef fish communities display a distinctive dusk/dawn changeover in
species composition
■ This relates primarily to feeding behaviors
■ Weather variations may also affect behavior
○ Tidally related activity patterns
○ Seasonality is reduced in the tropics
○ Inter-annual variation
● Nocturnal
○ Some planktivores- apogonidae (cardinalfishes), holocentridae (squirrelfish)
○ Some invertivores- Haemulidae (grunts), holocentridae (squirrelfish)
○ Some Carnivores
○ Large eyes , red coloring
● Long term temporal variation
○ Year to year variability high at the reefal/intermediate scale
■ Primarily driven by annual recruitment
■ Recruitment is affected by
● Larval supply
● Early predation on juveniles
● Inter- and intra specific competitors
● Trophic structure and feeding ecology
○ Planktivores: feed on plankton
○ Herbivores
● Trophic cascades
○ Adding or removing a higher trophic level may have effects on the biomass of
lower trophic levels
● Planktivores
○ Diurnal and nocturnal foraging
○ Visual feeders
○ Small protrusible jaws (expand as opens)
Trophic link to the pelagic environment
● Herbivores
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○ Generally diurnal
○ May be territorial or roving
○ May be denuders( bite vegetation) or scrapes
Specialized dentition: biting; tearing; beaks
○ Seaweed herbivore interactions
■ Physical and chemical defenses in seaweeds require corresponding
adaptation in herbivorous
○ Digestive tract- greater overall length than carnivores
○ Vertebrates do not possess cellulolytic enzymes so herbivorous fish have
evolved four main strategies:
■ 1. Low stomach pH to lyse plant cells
■ 2. Grinding pharyngeal mill (molar like teeth in throat)
■ 3. Trituration (grinding to a powder) in gizzard like stomach
■ 4. Endosymbiosis with bacteria in the gut to breakdown cellulose
● Mouth forms of invertivores
○ Chaetodontids
○ Balistidae
○ Grunts
● Piscivory
○ Diurnal and Nocturnal
○ Large mouths and sharp teeth
○ Camouflage and tails suited for burst swimming
○ Ambush or stalking: attack with strike and grab with sharp teeth - barracuda
Camouflaged ambush predators: dart and inhale - groupers, trumpetfish
○ Suction feeding via sling jaw mechanism - trumpetfish
○ Suction feeding via buccal cavity expansion - groupers, tarpon
● Reef fish Reproduction
○ Fecundity varies greatly depending on size, mating strategy & extend of parental
care
○ Most species are broadcast spawners
○ Mating may take place in pairs or spawning aggregations
○ Species that mate in pairs may exhibit complex courtfish behaviours - both color
and sound cues - diel, lunar or seasonal
○ Many pomacentridae, pseudochromis & balistidae exhibit parental care, with
males guarding nest & finning egg mass to aerate. Apogonidae males brood
eggs in mouth until hatching. Seahorse males brood in pouch
● Many seahorse species are included on the IUCN Red List of threatened species,
primarily as vulnerable and data deficient
○ Small brood size limits potential reproductive rate;
○ Male brooding means that young depend on parental survival for far longer than
in most fish;
○ Monogamy in most species that have been studied means that widowed animals
don't reproduce until they find a new partner;
○ Low population density suggests that lost partners are not quickly replaced
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Document Summary
>2 m for the goliath and queensland"s groupers. Great variety of morphological specializations which often result in unique lifestyles (ex. Traits: breath through gills, cold blooded , any kind of heterotroph(omnivore,herbivore,carnivore), largest species: mola mola. A wide variety of reproductive and social strategies. Dispersive reproductive stage and more sedentary adult stages. Often highly visual reproductive requiring clear water for feeding and reproductive. Morphological variability and niche diversification lead to co-occurring guilds of ecologically similar taxa. Generally long-long lived , otoliths reveal that. Smaller reef species can live been 12 and 45 years. There are a # of reef fish families that occur in the indo-pacific but not the carribean. Families occurring in both areas are generally more speciose in the indo-pacific, frequently with a great number of genera as well. Species composition gradients are evident across the pacific, less apparent in the caribbean. Total number of species and species per family decreases.
