Intergenerational effects of macroalgae on a reef coral: Major declines in larval survival but subtle changes in microbiomes

Published source details Beatty D.S., Clements C.S., Stewart F.J. & Hay M.E. (2018) Intergenerational effects of macroalgae on a reef coral: Major declines in larval survival but subtle changes in microbiomes. Marine Ecology Progress Series, 589, 97-114.
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This study is summarised as evidence for the following.

	Action	Category
	Transplant nursery-grown coral onto natural substrate Action Link
	Cultivate corals in an ex-situ nursery Action Link

Transplant nursery-grown coral onto natural substrate

A replicated study in 2014 in one protected coral reef and one fished reef off Viti Levu, Fiji (Beatty et al. 2018) found that transplanting nursery-grown corals Pocillopora damicornis onto natural substrate resulted in higher survival for juveniles when they were transplanted on substrate taken from, and transplanted to, the protected area compared to on substrate taken from, and transplanted to, the fished reef. Survival was higher for settled larvae on substrate taken from and transplanted to the protected area (day 4: protected area larvae: 49%, fished reef larvae: 64%, day 26: protected area larvae: 22%, fished reef larvae: 39%) than on substrate taken from and transplanted to the fished reef (day 4: protected area larvae: 12%, fished reef larvae: 29%, day 26: protected area larvae: 5, fished reef larvae: 8%). In addition, survival was lower for juveniles transplanted to the fished area on substrate fouled with macroalgae (day 4: 15%, day 26: 9%) compared to on unfouled substrate in the fished area or unfouled substrate in the protected area (day 4: 43−51%, day 26: 22−28%). In 2014, fragments of coral colonies were collected from 12 colonies from a protected area and 12 from an adjacent fished reef (100–500 m between protected and fished areas). Larvae from adults from the protected and fished areas were added to separate plastic dishes (10 larvae/dish) and settled on substrate gathered either from the protected area or fished reef (20 dishes/treatment). Settled larvae on either substrate were transplanted after four days either to the protected area or fished reef (13−18 pieces of substrate/treatment) and attached using nails and cable ties. Additionally, larvae on 14–15 pieces of substrate were transplanted in each of three treatments: transplanted to fished area with or without macroalgae on the substrate or transplanted to the protected area with no macroalgae. Survival was assessed after four and 26 days.

(Summarised by: William Morgan)
Cultivate corals in an ex-situ nursery

A replicated study in 2014 in Fiji (Beatty et al. 2018) found that cultivating corals in an ex-situ setting resulted in higher short-term survival for larvae originating from a protected area compared to those from a fished reef. Over a six-day period, larvae from the protected area had higher survival (94%) than larvae from the fished area (26–66%). This was true for larvae reared in protected area water (protected area larvae: 94%, fished area larvae: 66%) and fished area water (protected area larvae: 94%, fished area larvae: 26%). In addition, no differences were found in the microbiomes of larvae due to their origin (protected or fished reef) or the water they were held in (data reported as graphical analysis). In 2014, fragments of coral colonies were collected from a protected area and adjacent fished reef (12 colonies/area, 100–500 m between protected and fished areas) and held in separate containers. Four colonies from each area released larvae, and 10 larvae/colony were used to assess the microbiome. Additional larvae were gathered, and four treatments were established based on the origin of the larvae (protected or fished reef) and the origin of water (protected or fished reef), with 10 replicates/treatment, each with 10 larvae. Survival of larvae in containers was assessed after six days.

(Summarised by: William Morgan)