Larval Ecology Flashcards
Define holoplankton and provide some examples
- organisms that remain in a planktonic stage
- ex. krill, copepods, jellyfish, marine worms
Define meroplankton and provide some examples
- organisms that are only planktonic during larval stage
- ex. sea stars, sea urchins, crustaceans, octopus, reef fish
How do marine organisms clone themselves?
- fission (divide in half) –> diatoms and coral
- fragmentation (break piece off and regrow) –> coral, annelids, seagrasses
- vegetative growth (rhizomes) –> seagrasses
How do marine organisms sexually reproduce?
- broadcast spawning
- nesting/brooding
- internal fertilization (rare)
What does gonochorism mean?
Species has separate male and female individuals
What are the two types of hermaphroditism discussed?
- simultaneous (individual produces both gametes and is considered both sexes)
- sequential (sex changes over individuals lifetime) –> clownfish, parrotfish, gobies
What causes fertilization rates to decrease and what two processes increase the rate?
decrease = further apart partners are
increase = spawning congregations, synchronous gamete release
What are some differences between planktotrophic and lecithotrophic larva?
planktotrophic
- feed on small plankton
- spends months in planktonic stage
- long dispersal
- produced in large numbers with high mortality
lecithotrophic
- feeds on yolk sac from egg
- no feeding/digestive structures
- short dispersal
- only in planktonic stage for a couple of weeks
- few produced and with low mortality
What is direct development?
no planktonic stage, can be viviparous (grows inside mother) or oviparous (grows in egg)
In what oceanic regions are larva expected to have shorter planktonic stages?
in the tropics (associated with warmer temperatures)
What are the different routes larva use to find a suitable habitat to establish in?
- touch (direct proximity)
- sight (<50 m range)
- sound (<1 km range)
- smell (1-2 km range)
- light sensitivity and pressure (+100 km range)
How did scientists test the effects of cues on larva settlement?
- tested different distances of a speaker to larva in a tube
- most larva concentated less than 20 cm from source
What were the main findings of Schlesinger and Loya from the Red Sea?
- environmental variation from climate change was disrupting synchrony of fertilization
- breakdown was consistent across oocyte, polyp, colony and population level
- recruitment is affected and populations are at risk of extinction because gametes cannot fertilize
