Evaluating the causal basis of ecological success within the scleractinia: an integral projection model approach (original) (raw)
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PloS one, 2014
The reduction in coral cover on many contemporary tropical reefs suggests a different set of coral community assemblages will dominate future reefs. To evaluate the capacity of reef corals to persist over various time scales, we examined coral community dynamics in contemporary, fossil, and simulated future coral reef ecosystems. Based on studies between 1987 and 2012 at two locations in the Caribbean, and between 1981 and 2013 at five locations in the Indo-Pacific, we show that many coral genera declined in abundance, some showed no change in abundance, and a few coral genera increased in abundance. Whether the abundance of a genus declined, increased, or was conserved, was independent of coral family. An analysis of fossil-reef communities in the Caribbean revealed changes in numerical dominance and relative abundances of coral genera, and demonstrated that neither dominance nor taxon was associated with persistence. As coral family was a poor predictor of performance on contemporary reefs, a trait-based, dynamic, multi-patch model was developed to explore the phenotypic basis of ecological performance in a warmer future. Sensitivity analyses revealed that upon exposure to thermal stress, thermal tolerance, growth rate, and longevity were the most important predictors of coral persistence. Together, our results underscore the high variation in the rates and direction of change in coral abundances on contemporary and fossil reefs. Given this variation, it remains possible that coral reefs will be populated by a subset of the present coral fauna in a future that is warmer than the recent past.
Evaluating life‐history strategies of reef corals from species traits
2012
Abstract Classifying the biological traits of organisms can test conceptual frameworks of life-history strategies and allow for predictions of how different species may respond to environmental disturbances. We apply a trait-based classification approach to a complex and threatened group of species, scleractinian corals.
Biogeographical disparity in the functional diversity and redundancy of corals
Proceedings of the National Academy of Sciences of the United States of America, 2018
Corals are major contributors to a range of key ecosystem functions on tropical reefs, including calcification, photosynthesis, nutrient cycling, and the provision of habitat structure. The abundance of corals is declining at multiple scales, and the species composition of assemblages is responding to escalating human pressures, including anthropogenic global warming. An urgent challenge is to understand the functional consequences of these shifts in abundance and composition in different biogeographical contexts. While global patterns of coral species richness are well known, the biogeography of coral functions in provinces and domains with high and low redundancy is poorly understood. Here, we quantify the functional traits of all currently recognized zooxanthellate coral species ( = 821) in both the Indo-Pacific and Atlantic domains to examine the relationships between species richness and the diversity and redundancy of functional trait space. We find that trait diversity is rem...
Using empirical analyses of the effects of global climate change (GCC) and ocean acidification (OA) on the survival and calcification of early life stages of the common reef coral Pocillopora damicornis, we employed a demographic approach to forecast the consequences of GCC and OA on the population dynamics of this coral. We constructed a size-based demographic model using life-history tables and transition probabilities for a population of P. damicornis in southern Taiwan, and projected the population structure over ~100 y under differing scenarios of warming and acidification. The simulations incorporated a decline in larval survival due to increases in temperature and pCO2, modified growth rates due to rising temperature, and consideration of the effects of larvae from distant populations. With a local supply of larvae, an increase of pCO2 from 40.5 to 91.2 Pa reduces population density, and an increase in temperature from 26°C to 29°C results in population to extirpation within 100 years. When 10% of the larvae were supplied from distant populations, the population persisted regardless of high pCO2 (91.2 Pa) or temperature (ambient +3°C). These results indicate that: (1) populations of P. damicornis may be resistant to GCC and OA so long as it persists as part of a metapopulation capable of supplying larvae from spatially separated populations, and (2) early life stages can regulate the population dynamics of Pocillopora damicornis.
Comparative demography of two common scleractinian corals:Orbicella annularisandPorites astreoides
PeerJ, 2017
Background: Studies directed at understanding the demography and population dynamics of corals are relatively scarce. This limits our understanding of both the dynamics of coral populations and our capacity to develop management and conservation initiatives directed at conserving such ecosystems. Methods: From 2012 to 2014, we collected data on the growth, survival, and recruitment rates of two common Caribbean coral species, the stress-tolerant Orbicella annularis and the weedy Porites astreoides. A set of size-based population matrix model was developed for two localities in Northeastern Puerto Rico and used to estimate population growth rates () and determine the life cycle transition(s) that contribute the most to spatiotemporal differences in s. The model was parameterized by following the fate of 100 colonies of each species at the two sites for two years. Results: Our data indicate that spatial variability in vital rates of both species was higher than temporal variability. During the first year, populations of O. annularis exhibited s below equilibrium at Carlos Rosario (0.817) and Palomino (0.694), followed by a considerable decline at both sites during the second year (0.700 and 0.667). Populations of P. astreoides showed higher s than O. annularis during the first census period at Carlos Rosario (0.898) and Palomino (0.894) with a decline at one of the sites (0.681 and 0.893) during the second census period. Colony fate in both species exhibited a significant interaction with respect to location but not to time (G2 = 20.96; df = 3 for O. annularis and G2 = 9.55; df = 3 for P. astreoides). Discussion: The similar variability of s as well as the similar survival rates for both species during the two-year census period (2012-2014) show similar variability on demographic patterns in space and time. Our results suggest that location rather than time is important for the resiliency in coral colonies. Also, P. astreoides will show higher resistance to disturbance in the future than O. annularis.
Fecundity and the demographic strategies of coral morphologies
Understanding species differences in demographic strategies is a fundamental goal of ecology. In scleractinian corals, colony morphology is tightly linked with many demographic traits, such as size-specific growth and morality. Here we test how well morphology predicts the colony size-fecundity relationship in eight species of broadcast-spawning corals. Variation in colony fecundity is greater among morphologies than between species with a similar morphology, demonstrating that colony morphology can be used as a quantitative proxy for demographic strategies. Additionally, we examine the relationship between size-specific colony fecundity and mechanical vulnerability (i.e., vulnerability to colony dislodgment). Interestingly, the relationship between size-specific fecundity and mechanical vulnerability varied among morphologies. For tabular species, the most fecund colonies are the most mechanically vulnerable, while the opposite is true for massive species. For corymbose and digitate colonies, mechanical vulnerability remains relatively constant as fecundity increases. These results reveal strong differences in the demographic tradeoffs among species of different morphologies. Using colony morphology as a quantitative proxy for demographic strategies can help predict coral community dynamics and responses to anthropogenic change.
Coral populations in a rapidly changing environment
Journal of Experimental Marine Biology and Ecology
Contemporary coral populations are being forced to survive through disturbances at a variety of spatial and temporal scales. Understanding disturbances in the context of ecological processes may lead to models that accurately predict population trajectories. Few studies examine the key ecological processes that drive changes on reefs. Processes of major interest include reproduction, recruitment, post-settlement mortality, coral growth, fragmentation, and mortality. These population processes are dependent on macro-processes, such as predation and herbivory, which in turn vary in accordance with regional oceanography. Some coralreef regions experience high-frequency temperature anomalies, whereas other regions experience lowfrequency anomalies. It may turn out that corals in the high-frequency regions are also most likely to undergo rapid directional selection, and adapt to climate change, because only alleles experiencing persistent selection pressure may attain high frequency. Yet corals are clonal organisms and the same genotypes are often exposed to different environments and to different selective pressures. Therefore, when comparing coralpopulation trajectories across regions and oceans, it is critical to understand the key processes of corals within local, regional, and historical contexts.
Corals' prolonged struggle against unfavorable conditions
Galaxea, Journal of Coral Reef Studies, 2009
A central goal of coral-reef ecology is to define the key ecological processes that regulate reef populations under a rapidly changing environment. There is considerable need to move away from simply tracking reef state, and move toward more process orientated studies. Differential recruitment, growth, partial mortality, and mortality of corals are fundamental processes that need spatial evaluation using hierarchical sampling. Major changes to any one process will alter the state of the reef. Understanding these key processes, assessing their spatial variation and their relationship with state variables, such as coral cover, will lead to predictive models of population trajectories under different climate change scenarios. Predictions may even guide critical resource allocation to increase coral-reef management efforts at localities that are most likely to persevere in the prolonged struggle against unfavorable conditions.
Ecological Complexity, 2015
Ecological signs of Earth's biosphere forewarn an alarming trajectory towards a global mass-extinction. Assessing species performance and susceptibilities to decline is essential to comprehend and reverse this trend. Yet it is challenging, given difficulties associated with quantifying individual and population processes that are variable across time, space, and life-stages. We describe a new approach to estimating and comparing species performances that combines empirical data, a novel theoretical consideration of population dynamics, and modern statistics. Our approach allows for a more realistic continuous representation of individual performances along development stages while taking into account non-linearity, and natural variability as captured by spatio-temporally replicated observations. We illustrate its application in a coral meta-assemblage composed of populations of the three major reef-building taxa Acropora, Pocillopora, Porites. Using a unique set of highly replicated observations of individual coral dynamics under various environmental conditions, we show how taxa differ in their investment in recruitment and size-specific aptitude for growth and survival, notably through different use of clonal shrinkage, fragmentation, fission, and fusion processes. Our results reveal contrasting life-history trade-offs among taxa which, along with differing patterns of density-dependent recruitment, modulate species responses to decline. These differences in coral life history traits reflect opposing life-strategies, imply regulation at differing lifestages, and explain divergence in species trajectories. Our findings indicate a high potential for resilience in Pocillopora and Porites populations, thanks respectively to a sustained recruitment that promotes demographic elasticity through replacement of individuals, and a steady resistance to mortality which confers persistence through lingering of individuals. Resilience in Acropora appears more arbitrary, given high susceptibility to perturbations and dependency of recruitment on presence of established local populations. We identify management actions that can complement Acropora's life history and benefit recovery of its populations following mortality events. Our regression-modelling approach to quantifying and comparing species performances in different population processes is applicable to all taxa, as illustrated even those with complex clonal life histories, and can be implemented at wide spatio-temporal and taxonomic coverage. It can promote more accurate representation of species dynamics in both descriptive and predictive modelling approaches. The semi-parametric contrast curve method we develop facilitates comparing response variables along continuous explicative metrics while accounting for multiple sources of complexity in empirical data. It should widely benefit investigations in ecology and quantitative science.
Background: Studies directed at understanding the demography and population dynamics of corals are relatively scarce. This limits our understanding of both the dynamics of coral populations and our capacity to develop management and conservation initiatives directed at conserving such ecosystems. Methods: From 2012 to 2014, we collected data on the growth, survival, and recruitment rates of two common Caribbean coral species, the stress-tolerant Orbicella annularis and the weedy Porites astreoides. A set of size-based population matrix model was developed for two localities in Northeastern Puerto Rico and used to estimate population growth rates () and determine the life cycle transition(s) that contribute the most to spatiotemporal differences in s. The model was parameterized by following the fate of 100 colonies of each species at the two sites for two years. Results: Our data indicate that spatial variability in vital rates of both species was higher than temporal variability. During the first year, populations of O. annularis exhibited s below equilibrium at Carlos Rosario (0.817) and Palomino (0.694), followed by a considerable decline at both sites during the second year (0.700 and 0.667). Populations of P. astreoides showed higher s than O. annularis during the first census period at Carlos Rosario (0.898) and Palomino (0.894) with a decline at one of the sites (0.681 and 0.893) during the second census period. Colony fate in both species exhibited a significant interaction with respect to location but not to time (G2 = 20.96; df = 3 for O. annularis and G2 = 9.55; df = 3 for P. astreoides). Discussion: The similar variability of s as well as the similar survival rates for both species during the two-year census period (2012–2014) show similar variability on demographic patterns in space and time. Our results suggest that location rather than time is important for the resiliency in coral colonies. Also, P. astreoides will show higher resistance to disturbance in the future than O. annularis.