Caribbean Acropora Restoration Guide - The Florida Reef ...

Reproduction Woes
Acropora corals rely heavily upon asexual reproduction via fragmentation, and although sexual reproduction
does occur, they have shown very little success of sexual recruitment, likely due to the low abundance
of surviving parent colonies as well as declining water quality and reduced substrate availability. While
asexual reproduction through fragmentation can result in expansion of local populations, this reproductive
mode yields new colonies that are genetically identical to the parent (i.e., clones). Overreliance on asexual
fragmentation limits the number of genetically distinct colonies, both at local scales and throughout the
species range.
Reduced genotypic diversity suggests that there may not be enough genetically distinct parents to ensure
successful sexual reproduction. Because corals like Acropora have physiological barriers to prevent the crossing
of gametes (sperm and eggs) from the same parent, multiple distinct parent genotypes are required within
a spawning area for successful gamete fertilization. Thus, unless multiple genetically distinct individuals
are in proximity to each other to reproduce, genotypic diversity may not increase over time. By increasing
population numbers and the number of distinct parent genotypes at local scales through propagation and
transplantation of nursery grown fragments, sexual reproduction and recruitment are expected to have
higher success rates ultimately aiding in the natural recovery of the species.
This figure, used with permission and provided by Mark Vermeij
LARVAL AVAILABILITY
Gamete bundles float
to sea surface
Gamete bundles
break apart
Fertilization occurs
Embryo
Days-weeks
in plankton
Planula larva
Broadcast spawners
1-2 cycles per year
many gametes
SETTLEMENT
ECOLOGY
Settlement
Primary
polyp
> 2 years
2–3 months
POST-SETTLEMENT
ECOLOGY
Figure 1: Life cycle of Acropora corals. Acropora corals reproduce both sexually and asexually through fragmentation (not shown in
this figure). Fragmentation is a simpler mode of reproduction with fewer vulnerable stages and an important strategy for many Acropora
corals. The techniques described within this guide are based on the natural capacity for fragmentation in these species.
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