Effects of sediment exposure on corals: a systematic review of experimental studies

Table 7 Results of best-fit dose–response meta-regression (DRMA) models for coral responses where sufficient data were available to assess the relationship between sediment exposure (‘dose’) and magnitude of the coral response of-interest (standardized effect size, Hedges’ d)

Coral age class	Continuous coral response	Deposited or suspended sediment*	# Treatment groups* (controls included/excluded)	# Studies/articles in DRMA	# Species/genera in DRMA	Dose–response I² Statistic*	Dose–response threshold* (DS: mg/cm²/day; SS: mg/L)
Gametes	Fertilization success rate	SS	110/86	10/6	4/2	82.3%	30.4 (p < 0.0001)
Larvae	Larval survival rate	SS	50/42	4/3	4/2	73.0%	n.s
	Settlement rate	DS	71/61	7/6	2/2	84.6%	1.3 (p < 0.0001)
	Settlement rate	SS	26/20	6/3	3/2	88.3%	n.s
Juveniles	Recruit mortality rate	DS	132/87	3/3	4/2	47.1%	13.8 (p = 0.025)
Adults	P/R ratio	DS	20/10	3/3	4/4	58.4%	n.s
	Photosynthetic efficiency	DS	181/141	8/6	9/6	76.8%	3.2 (p = 0.005)
	Photosynthetic efficiency	SS	217/164	5/4	6/5	21.4%	n.s
	Growth rate	DS	29/19	8/8	8/5	41.5%	n.s
	Partial tissue mortality rate	DS	140/115	4/4	11/8	86.9%	n.s
	Total colony mortality rate	SS	47/33	4/4	6/4	0.0%	n.s

Analyses using deposited or suspended sediment datasets are indicated as ‘DS’ and ‘SS,’ respectively. A ‘treatment group’ is an experimental unit of corals exposed to the same exposure conditions within a study—these may be control conditions (no sediment exposure) or treatment conditions of differing exposure concentrations and/or durations. The ‘Dose–Response I² Statistic’ is a measure that indicates the percentage of variance in a meta-analysis that is attributable to heterogeneity among dose–response comparisons within study. Heterogeneity is substantial when I² is above 75%. The ‘Dose–Response Threshold’ for a coral response significantly affected by sediment concentration was the minimum exposure value at which DRMA 95% CI no longer overlapped with zero (where zero indicates no difference between a treatment group and its control, see Fig. 2C). Rows in bold represent significant relationships (p ≤ 0.05) between sediment exposure and the effect size of the corresponding coral response and ‘n.s.’ indicates a non-significant relationship (p > 0.05)

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