Coral Reproduction

Why is how organisms reproduce important?

Adult replacement/variability, genetic variability, and adaptation/evolution

Do marine organisms reproduce in all sorts of ways?

yes

Do marine organisms have complex life histories?

yes

Do marine organisms utilize the same or vastly different habitats throughout life phases?

vastly different habitats

what is an obligate pelagic larval phase?

A developmental stage in the life cycle of many marine organisms where the offspring must spend a mandatory period of living as plankton in the open ocean water column before they can transform and settle into their adult habitats

what type of life phases do many marine organisms have?

obligate pelagic larval life-phases

What is broadcast spawning?

A reproductive strategy used by many marine organisms, where eggs and sperm are released into the water column simultaneously, allowing for external fertilization in the open ocean.

What is brooding?

brooders internally fertilize eggs from sperm released into the water column and release planula larvae

Do corals have one or many reproductive modes?

Many

What was spawning likely ancestral to?

brooding

What is hermaphrodism?

A reproductive strategy where an individual coral polyp or an entire coral colony produces both male (sperm) and female (eggs) reproductive organs or gametes

What are the two forms of hermaphrodism in corals?

simultaneous and sequential

What is simultaneous hermaphrodism?

polyps are both male and female simultaneously and may release egg and sperm sequentially or simultaneously

What is sequential hermaphrodism

A biological process in which an organism changes its sex at a specific point during its lifetime typically either protandry or sex switching

What is protandry?

begin life as a male, and eventually become female

What is sex switching?

switching back and forth between sexes, sometimes annaully or in response to environmental cues

What is gonochorism?

A reproductive system in which individual coral colonies have distinct separate sexes

Is gonochorism common?

no it is relatively rare when compared to hermaphrodism

What does it mean for a corals to be gynodioecious?

a rare breeding system in corals where a population or species consists of a mix of hermaphroditic individuals and female individuals

Do all corals in a species reproduce the same way?

No corals are plastic and the same species can reproduce in different ways in different regions

What are the two types of mass coral spawning?

Multispecific spawning and mass spawning

What is multispecific spawning

two or more species spawning on the same evening

what is mass spawning?

many species of invertebrates (not just corals) spawning on the same evening

Where does spawning synchrony appear to be the highest?

mid-latitudes

What is hybridization?

Occurs when eggs and sperm from two different genetically distinct coral species combine (cross-fertilization) to produce a viable hybrid offspring

Is synchrony advantageous or not?

synchrony is advantageous

Why is synchrony advantaegous?

maximizes the likelihood for fertilization, may aim for optimal environmental conditions for reproductive success

What happens during mass coral spawning?

predation

What is temporal isolation in multi-specific spawning?

A barrier that prevent different species from cross-breeding by separating the timing of their gamete release

how do corals synchronize spawning

by using seasonal cues, proximate cues and ultimate cues

What do seasonal cues decide?

time of year, or month

What are the seasonal cues?

peak SST, day length, and wind/doldrums

What do proximate cues decide?

the night of spawning

What are the proximate cues?

lunar cycle and days after full moon

What do ultimate cues decide?

the time of spawning

What are the ultimate cues?

sunset (usually time since sunset and chemical cues from congeners or even other species

what are congeners?

belonging to the same taxonomic genus

What may also stimulate simultaneous colony-wide spawning in addition to stimulating congeners to spawn?

Chemical cues

How to corals maximize the chance that egg and sperm meet?

by releasing egg/sperm bundles that can concentrate gametes at air/sea boundary

What is self-fertilization?

sperm and egg from the same individual fertilize

What is asexual brooding?

a brooded larvae is developed without the fertilization of an egg, genetic clones

What are pre-zygotic reproductive barriers?

Any biological mechanism that prevents two different species or populations from mating or fertilizing an egg from a zygote

What is an example of a pre-zygotic reproductive barrier

coral gametes prefer to fertilize with conspecifies

what is a conspecific

Belonging to the same species

is coral reproduction successful without recruitment?

no

what is a planulae larvae

The free-swimming, microscopic juvenile stage of a coral

how do planulae larvae of broadcast spawners develop?

pelagically

do planulae larvae of broadcast spawners have symbionts?

no symbionts

What type of planulae larvae do brooder have and at what speed do they settle?

brooders release competent larvae that settle rapidly

what is the timeframe for settlement of planulae larvae from brooders?

0-120 days

what is the timeframe for settlement of planulae larvae from broadcast spawners?

approximately 3-120 days but this is hugely variable and hard to measure on site

Are the dispersal capabilities for species the same or different?

very different

is recruitment an understood process?

recruitment is a poorly understood process

what is the recruitment mortality rate?

recruits have high mortality

where do recruits go?

in cracks and crevices to avoid predation and overgrowth

do brooders have high recruitment success and why?

brooders have high recruitment success as planulae settle close to natal colonies

When do broadcast spawning corals recruit?

in stochastic (random) events when conditions are favorable

What are stresses to reproduction

thermal stress, uv light, salinity, sedimentation/turbidity, nutrient, oil and dispersants, herbicides and insecticides, and other pollutants like stormwater runoff

What happens if temperatures get warmer earlier?

peak SST may occur at a different time than usual which could shift spawning time and make it more difficult to preditc

what could happen if spawning time shifts?

gametes and larvae could be exposed to a new set of environmental conditions

Is acidification bad for coral reproduction?

acidification is bad for coral reproduction

What are the challenges to studying coral reproduction?

timing corals spawn typically once a year often during hurricane season and usually at night

how is coral reproduction studied?

direct observation/collection, in the lab, or by remote video

How is coral reproduction studied in the lab?

tissue histology and microscopy, and paraffin histoligcal methods

What occurs during tissue histology and microscopy

samples are brought back to the lab and they look for gametes are larvae

what happens during paraffin histological methods?

tissues are decalcified, and paraffinized, then embedded into a block of wax and sectioned and stained and then read on slides

what does decalcifying tissue do?

gets rid of the skeleton

what does praffinizing the tissues do?

remove h2o and replace with wax

how does OA impact reproduction?

Impairing fertilization, larval behavior, and post-settlement survival