Demographic Mechanisms of Reef Coral Species Winnowing from Communities under Increased Environmental Stress

Riegl, Bernhard; Cavalcante, Geórgenes H.; Bauman, Andrew G.; Steiner, Sascha C. C.; Purkis, Sam J.

doi:10.3389/fmars.2017.00344

Cited by 36 publications

(44 citation statements)

References 86 publications

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“…In addition, temperature datasets from the region (climexp.knml.nl) were explored for trends and spikes in anomalies, minima, maxima, and means. Air temperatures from Sharjah correlated highly with in situ time‐series of water temperature at monitored reef sites from 2013 to 2018 (Riegl et al., ). Therefore, annual anomalies as proxy for heat stress were calculated from the longer air‐temperature time‐series.…”

Section: Methodsmentioning

confidence: 98%

“…Climate change effects were examined by reducing connectivity (Figueiredo et al., ). The metapopulation model took a source (population 1)—sink (population 4) form in a linear hierarchy (Pop1→Pop2→Pop3←→Pop4) with populations 3 and 4 having two‐way connectivity along the coast (Riegl et al., ). Step‐wise, 10‐fold decrease in fertility/local recruitment (a fractional multiplier, “connectivity factor”) in subpopulation 1 and in connectivity between the remaining subpopulations, were examined.…”

Section: Methodsmentioning

confidence: 99%

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Population collapse dynamics in Acropora downingi, an Arabian/Persian Gulf ecosystem‐engineering coral, linked to rising temperature

Riegl

Johnston

Purkis

et al. 2018

Global Change Biology

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As in the tropical Atlantic, Acropora populations in the southern Persian/Arabian Gulf plummeted within two decades after having been ecosystem engineers on most wave-exposed reefs since the Pleistocene. Since 1996/1998 live coral cover in the Gulf declined by over 90% in many areas, primarily due to bleaching and diseases caused by rising temperatures. In the formerly dominant table-coral species A. downingi, population dynamics corresponding to disturbance regimes was quantified in three transition matrices (lower disturbance pre-1996; moderate disturbance from 1998 to 2010 and 2013 to 2017, disturbed in 1996/1998, 2010/11/12, 2017). Increased disturbance frequency and severity caused progressive reduction in coral size, cover, and population fecundity. Small size-classes were bolstered more by partial colony mortality than sexual recruitment. Some large corals had a size refuge and resisted die-back but were also lost with increasing disturbance. Matrix and biophysical larval flow models suggested one metapopulation. Southern, Arabian, populations could be connected to northern, Iranian, populations but this connectivity was lost under assumptions of pelagic larval duration at rising temperatures shortened to a third. Then, the metapopulation disintegrated into isolated populations. Connectivity required to avoid extinctions increased exponentially with disturbance frequency and correlation of disturbances across the metapopulation. Populations became unsustainable at eight disturbances in 15 years, when even highest theoretical recruitment no longer compensated mortality. This lethal disturbance frequency was 3-fold that of the moderately disturbed monitoring period and 4-fold of the preceding low-disturbance period-suggesting ongoing shortening of the disturbance-free period. Observed population collapse and environmental changes in the Gulf suggest that A. downingi is heading toward at least functional extinction mainly due to increasingly frequent temperature-induced mortality events, clearly linked to climate change.

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Section: Methodsmentioning

confidence: 98%

Section: Methodsmentioning

confidence: 99%

Population collapse dynamics in Acropora downingi, an Arabian/Persian Gulf ecosystem‐engineering coral, linked to rising temperature

Riegl

Johnston

Purkis

et al. 2018

Global Change Biology

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“…A decline in coral colony size is a common response to adverse conditions by tropical scleractinians (Hughes and Tanner , Riegl and Purkis , Riegl et al. , but see Pisapia et al. for a case of the alternate trend), and on many reefs, it is a feature of the globally intensifying coral reef crisis (Fong and Glynn , Hernandez‐Pacheco et al.…”

Section: Discussionmentioning

confidence: 99%

“…Moreover, where changes are detected in low abundance coral communities, inferring ecological meaning from small absolute change (that can be relatively large) probably is unreliable (MacKenzie et al 2005). Demographic approaches (sensu Hughes 1984, Caswell 2001, Riegl et al 2017) provide appropriate tools for such situations (Riegl et al 2017), and here, they reveal the effects of Hurricanes Irma and Maria on Orbicella annularis.…”

Section: Overviewmentioning

confidence: 99%

“…A decline in coral colony size is a common response to adverse conditions by tropical scleractinians (Hughes and Tanner 2000, Riegl and Purkis 2015, Riegl et al 2017, but see Pisapia et al 2016 for a case of the alternate trend), and on many reefs, it is a feature of the globally intensifying coral reef crisis (Fong and Glynn 1998, Hernandez-Pacheco et al 2011, Riegl et al 2017. Such declines might not be detected in analyses of coral cover, because cover is insensitive to the ways in which it is distributed among colonies (Hughes and Jackson 1985).…”

Section: The Demographic Responses To Two Hurricanesmentioning

confidence: 99%

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The demography of hurricane effects on two coral populations differing in dynamics

Edmunds

2019

Ecosphere

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On most tropical coral reefs, decades of disturbances have ratcheted down coral cover to create low abundance communities. In such a state, the reefs of St. John, US Virgin Islands, were hit by two Category 5 hurricanes in September 2017, yet the effects on two sites dominated by Orbicella annularis were minor in terms of coral cover. To explore the implications of this outcome, the fates of O. annularis colonies were determined from photoquadrats and used to prepare size‐based matrix models for the year preceding the storms and the four months bracketing the storms. The populations displayed contrasting dynamics from 1988 to July 2017, with coral cover declining from 43% to 5% at Yawzi Point but remaining at ~30% at Tektite. Over this period, colony sizes declined, with ≥82% having planar areas ≤50 cm2 (i.e., the smallest size class) by July 2017, and while densities declined from 47 to 8 colonies/m2 at Yawzi Point, they increased from 36 to 51 colonies/m2 at Tektite. Hurricanes Irma and Maria depressed coral cover by 1–4%, transitioned colonies into the smallest size class (>87% by November), killed 27% and 5% of the colonies in the smallest size class at Yawzi Point and Tektite, respectively, and depressed the 5‐yr intrinsic rate of population growth (λ) to 0.53–0.87. Twenty‐year projections suggested these demographic effects will not have ecologically meaningful impacts on population size, at least compared to projections initiated assuming Hurricanes Irma and Maria had not occurred. With low cover of O. annularis distributed among many small colonies, future disturbances may play more important roles in winnowing the few remaining host genotypes rather than further depressing coral cover.

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Diet quality impairs male and female reproductive performance and affects the opportunity for selection in an insect model

Winkler

Janicke

2022

Ecology and Evolution

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Demographic Mechanisms of Reef Coral Species Winnowing from Communities under Increased Environmental Stress

Cited by 36 publications

References 86 publications

Population collapse dynamics in Acropora downingi, an Arabian/Persian Gulf ecosystem‐engineering coral, linked to rising temperature

Population collapse dynamics in Acropora downingi, an Arabian/Persian Gulf ecosystem‐engineering coral, linked to rising temperature

The demography of hurricane effects on two coral populations differing in dynamics

Diet quality impairs male and female reproductive performance and affects the opportunity for selection in an insect model

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