Recruitment to the reef
column spacer Recruitment
 
 

Survival during early life

 

Recruitment in sexually reproducing animals involves 3 main topics: 1) spawning, larval development, and dispersal of larvae, 2) settlement and metamorphosis, and 3) survival during early life.  The third topic is considered in this section.  The other recruitment topics are accessible via the icons.

Survival during early llife in sexually reproducing animals is considered here for fishes & turtles, while INVERTEBRATES are presented in their own section.

title for recruitement to the reef part of BCCR hot-button icon for linking to the topic of spawning, larval development, & dispersal of larvae in BCCR hot-button icon for linking to the topic of settlement & metamorphosis during early life in BCCR hot-button icon for linking to the topic of survival during early life in BCCR
 
 

Survival during early life: vertebrates: fishes & turtles

 

photograph of juvenile sergeant-majorFrom the moment eggs of fishes are released from the parent the eggs and later developmental stages face a gamut of hungry mouths, both in the plankton and later on the reef face. Of the hundreds or thousands eggs produced by coral-reef fishes, only a tiny fraction will survive as larvae and eventually settle and metamorphose. As small juveniles on the reef the fishes will confront a new set of predators.

Studies on recruitment dynamics in Caribbean coral-reef fishes emphasise the importance of the transition between the planktonic larval stage and the bottom-dwelling juvenile stage, and the events associated with survival during this transition are thought ultimately to determine recruitment success. Kaufman et al. 1992 Envir Biol Fishes 34: 109; Searcy & Sponaugle 2001 Ecology 82: 2452.

 

A transition juvenile sergeant-major Abudefduf saxatilis
finds protection in a shallow part of the reef 0.2X

 
 
seahorse dive leader in BCCR photograph of grunts on reef taken from a video

"If all grunt offspring survived, then we'd be knee-deep in them. They don't, of course, as attrition occurs throughout their lives. The biggest loss takes place during the vulnerable transition from larva to juvenile, but high mortalities also occur during the juvenile stage" - Little Cayman Island 2003

NOTE Haemulon spp.

 
 

Young fishes as prey

 

photograph of French gruntsgraph showing survival of French Grunts over first 300 days of life
In St. Croix, only about 10% of French grunts survive to their first month of life on the reef and less than 1% survive to their first year. The young fish may be eaten outright, or prevented from settling by territorial species such as damselfishes, thus rendering them more susceptible to predation from other fishes. Shulman & Ogden 1987 Mar Ecol Progr Ser 39: 233.




French grunts Haemulon flavolineatum 0.15X

  photo composite of surgeonfish and Beaugregory damselfish
Damselfishes in St. Croix, most notably beaugregories, interfere photo-isolate of yellowtail damselfishwith settlement of larval ocean surgeonfishes. Not only is settlement less in the presence of the damselfishes, but mortality of the juvenile surgeonfishes following settlement is also directly related to the level of aggression received from the beaugregories and perhaps other species of damselfishes. Risk 1998 Envir Biol Fish 51: 377.
  Let's hear from the damselfishes on the matter:
 
cartoon of octopus and damselfish 1 in a series of 12 cartoon of octopus and damselfish 2 in a series of 12
 
cartoon of octopus and damselfish 3 in a series of 12 cartoon of octopus and damselfish 4 in a series of 12
 
cartoon of octopus and damselfish 5 in a series of 12 cartoon of octopus and damselfish 6 in a series of 12
 
cartoon of octopus and damselfish 7 in a series of 12 cartoon of octopus and damselfish 8 in a series of 12
 
cartoon of octopus and damselfish 9 in a series of 12 cartoon of octopus and damselfish 10 in a series of 12
 
cartoon of octopus and damselfish 11 in a series of 12 cartoon of octopus and damselfish 12 in a series of 12
 
 

Hatchling turtles as prey

 
 
seahorse dive leader for Biology of Caribbean Coral Reefs website photograph of hawksbill turtle taken from a video Hawksbill turtles Eretmochelys imbricata spend several years at sea, during which time they grow to a mature size. It is not clear what they eat during their pelagic phase but, when they arrive back on the reef their preference is to eat sponges, as this individual is doing - Turks & Caicos 2003
 
  Several or all sea-turtle species migrate long distances from feeding/copulation spots to egg-laying spots on sandy beaches. On arrival at the laying beach, a female crawls up the beach and lays up to hundreds of eggs that hatch after a few weeks. After hatching, the baby turtles must undertake a risky crawl down the beach, then embark upon a hazardous swim through the shallow reef area to deeper water beyond. Predators of hatchlings include birds, fishes, and sharks.
 
photo collage of sea turtles laying eggs and after hatchin
 
 
cartoon with turtle-hatchling quiz
 
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