Landscape‐scale patterns of nutrient enrichment in a coral reef ecosystem: implications for coral to algae phase shifts

Ecological Applications, Journal Year: 2020, Volume and Issue: 31(1)

Published: Sept. 24, 2020

Nutrient pollution is altering coastal ecosystems worldwide. On coral reefs, excess nutrients can favor the production of algae at expense reef-building corals, yet role in driving community changes such as shifts from to macroalgae not well understood. Here we investigate potential anthropogenic nutrient loading recent coral-to-macroalgae phase on reefs lagoons surrounding Pacific island Moorea, French Polynesia. We use nitrogen (N) tissue content and stable isotopes (δ15 N) an abundant macroalga (Turbinaria ornata) together with empirical models discharge describe spatial temporal patterns enrichment lagoons. then employ time series data test whether increases are associated nutrients. Our results revealed that N were linked several factors, including rainfall, wave-driven circulation, distance sources, especially human sewage. Reefs near large watersheds, where inputs sewage agriculture high, have been consistently enriched for least last decade. In many these areas, corals decreased increased, while lower levels input maintained high cover low macroalgae. Importantly, patchy occurred despite substantial island-wide density biomass herbivorous fishes over period. Together, indicate may be important driver Moorea even though harbor diverse herbivore assemblage. These emphasize bottom-up factors play underscore critical importance watershed management reducing other land-based pollutants reef ecosystems.

Language: Английский

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Overfishing and the ecological impacts of extirpating large parrotfish from Caribbean coral reefs

Ecological Monographs, Journal Year: 2019, Volume and Issue: 90(2)

Published: Dec. 23, 2019

Abstract The unique traits of large animals often allow them to fulfill functional roles in ecosystems that small cannot. However, are also at greater risk from human activities. Thus, it is critical understand how losing impacts ecosystem function. In the oceans, selective fishing for alters demographics and size structure numerous species. While community‐wide a major theme terrestrial research, ecological consequences removing marine remain understudied. Here, we combine survey data 282 sites across Caribbean with field experiment investigate altering parrotfish populations coral reef communities. We show Caribbean‐wide, skewed toward smaller individuals, fishes <11 cm length comprising nearly 70% population most heavily fished locations vs. ~25% minimally sites. Despite these differences structure, had similar overall biomass. As result, algal cover was unrelated biomass instead, negatively correlated density parrotfishes. To mechanistically explore parrotfishes shape benthic communities, manipulated fishes’ access benthos create three distinct fish communities different structure. found excluding or medium‐sized did not alter grazing rates but caused respective 4‐ 10‐fold increases Unexpectedly, branching corals benefited whereas growth mounding species impaired. Similarly, led unexpected recruitment were absent when both medium bodied excluded. Our highlight driving dynamics on reefs suggests diversity an important component herbivore function reefs. This study adds growing body literature revealing ramifications sheds new light down reshape

Language: Английский

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Detecting Thresholds of Ecological Change in the Anthropocene

Annual Review of Environment and Resources, Journal Year: 2022, Volume and Issue: 47(1), P. 797 - 821

Published: Sept. 6, 2022

Ecological thresholds comprise relatively fast changes in ecological conditions, with respect to time or external drivers, and are an attractive concept both scientific policy arenas. However, there is considerable debate concerning the existence, underlying mechanisms, generalizability of across a range subdisciplines. Here, we usethe general scale as unifying framework which systematically navigate variability within threshold research. We review literature show how observational adopted any one study, defined by its organizational level, spatiotemporal grain extent, analytical method, can influence detection magnitude. highlight need for nuance synthetic studies thresholds, could improve our predictive understanding thresholds. Nuance also needed when translating concepts into policies, including contingencies uncertainties.

Language: Английский

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How do we overcome abrupt degradation of marine ecosystems and meet the challenge of heat waves and climate extremes?

Global Change Biology, Journal Year: 2019, Volume and Issue: 26(2), P. 343 - 354

Published: Dec. 24, 2019

Abstract Extreme heat wave events are now causing ecosystem degradation across marine ecosystems. The consequences of this heat‐induced damage range from the rapid loss habitat‐forming organisms, through to a reduction in services that ecosystems support, and ultimately impacts on human health society. How we tackle sudden emergence ecosystem‐wide has not yet been addressed context waves. An examination recent waves around Australia points potential important role respite or refuge environmental extremes can play enabling organismal survival. However, most ecological interventions being devised with target mid late‐century implementation, at which time many ecosystems, targeted towards, will have already undergone repeated widespread induced degradation. Here, our assessment merits proposed interventions, spectrum approaches, counter extremes, reveals lack preparedness effects extreme conditions influence these projected continue impact coming years, long before be developed. Our approaches technologically ready likely socially acceptable locally deployable only, whereas those scalable—for example features as large major reef systems—are close testable, unlikely obtain social licence for deployment. Knowledge timescales survival via refuge, inferred field observations help test such intervention tools. growing frequency increases urgency consider mitigation tools support immediate future, while global climate and/or formulated.

Language: Английский

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Long‐term dynamics and drivers of coral and macroalgal cover on inshore reefs of the Great Barrier Reef Marine Park

Ecological Applications, Journal Year: 2019, Volume and Issue: 30(1)

Published: Sept. 24, 2019

Quantifying the role of biophysical and anthropogenic drivers coral reef ecosystem processes can inform management strategies that aim to maintain or restore structure productivity. However, few studies have examined combined effects multiple drivers, partitioned their impacts, established threshold values may trigger shifts in benthic cover. Inshore fringing reefs Great Barrier Reef Marine Park (GBRMP) occur high-sediment, high-nutrient environments are under increasing pressure from acute chronic stressors. Despite world-leading management, including networks no-take marine reserves, relative declines hard cover 40-50% occurred recent years, with localized but persistent macroalgal dominance on some reefs. Here we use boosted regression tree analyses test importance using a long-term (12-18 yr) data set collected at four island groups. Coral were negatively correlated all groups, particularly when was above 20%. Although each group had different disturbance-and-recovery histories, degree heating weeks (DHW) routine wave exposure consistently emerged as common In addition, combinations sea-surface temperature, nutrient turbidity parameters, high (primary) floodwater, depth, grazing fish density, farming damselfish zoning variously contributed changes group. Clear apparent for exposure, cover, weeks, chlorophyll a, cyclone however, variable among Our findings demonstrate inshore communities typically structured by broadscale climatic perturbations, superimposed upon unique sets local-scale drivers. rapidly escalating climate change impacts largest threat GBRMP globally, our suggest proactive actions effectively reduce stressors local scales should contribute improved resistance recovery potential following disturbances.

Language: Английский

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Resilience of Octocoral Forests to Catastrophic Storms

Scientific Reports, Journal Year: 2020, Volume and Issue: 10(1)

Published: March 9, 2020

After centuries of human-mediated disturbances, Caribbean reef communities are vastly different from those described in the 1950s. Many functionally dominated by macroalgae, but this community state represents only one several possibilities into which present-day coral reefs can transition. Octocorals have always been abundant on reefs, increases their abundance over last few decades suggest that arborescent octocorals potential to expand populations hitherto had scleractinians. Here we show octocoral-dominated at three sites fringing St. John, US Virgin Islands, were resilient effects two Category 5 hurricanes 2017. We describe dynamics octocoral five years shallow (~9-m depth), and test for Hurricanes Irma Maria. The depressed densities juvenile adult colonies as much 47%. However, there weak species richness relative abundances species. did not alter patterns spatial variability structure existed among prior storms. density recruits (individuals ≤ cm high) was reduced year following hurricanes, mainly due a decline <0.5 cm, returned pre-storm 2019. Persistently high recruitment provides mechanism supporting ecological resilience these communities. Continuing environmental degradation is threat all tropical marine communities, John illustrate how "octocoral forests" persist structurally dominant reefs.

Language: Английский

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Coral reef benthic community changes in the Anthropocene: Biogeographic heterogeneity, overlooked configurations, and methodology

Global Change Biology, Journal Year: 2021, Volume and Issue: 28(6), P. 1956 - 1971

Published: Dec. 24, 2021

Non-random community changes are becoming more frequent in many ecosystems. In coral reefs, towards communities dominated by other than hard corals increasing frequency, with severe impacts on ecosystem functioning and provision of services. Although new research suggests that a variety alternative (i.e. not corals) exist, knowledge the global diversity reef benthic communities, especially those algae, remains scattered. this systematic review meta-analysis 523 articles, we analyse different reported to date discuss advantages limitations methods used study these changes. Furthermore, field cover data (1116 reefs from ReefCheck database) explore biogeographic latitudinal patterns dominant organisms. We found mismatch between literature focus coral-algal (over half studies analysed) observed natural patterns. identified strong patterns, largest most biodiverse regions (Western Central Indo-Pacific) presenting previously overlooked soft-coral-dominated as abundant community. Finally, potential biases associated overlook ecologically important cryptobenthic technological advances improving monitoring efforts. As inevitably swiftly change under changing ocean conditions, there is an urgent need better understand distribution, dynamics well ecological societal communities.

Language: Английский

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Responses of Coastal Ecosystems to Climate Change: Insights from Long-Term Ecological Research

BioScience, Journal Year: 2022, Volume and Issue: 72(9), P. 871 - 888

Published: Feb. 5, 2022

abstract Coastal ecosystems play a disproportionately large role in society, and climate change is altering their ecological structure function, as well highly valued goods services. In the present article, we review results from decade-scale research on coastal shaped by foundation species (e.g., coral reefs, kelp forests, marshes, seagrass meadows, mangrove barrier islands) to show how attributes We demonstrate value of site-based, long-term studies for quantifying resilience systems forcing, identifying thresholds that cause shifts state, investigating capacity adapt biological mechanisms underlie it. draw extensively conducted at studied US Long Term Ecological Research Network, where long-term, spatially extensive observational data are coupled with shorter-term mechanistic understand consequences change.

Language: Английский

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Modeling the effects of selectively fishing key functional groups of herbivores on coral resilience

Ecosphere, Journal Year: 2024, Volume and Issue: 15(1)

Published: Jan. 1, 2024

Abstract Mounting evidence suggests that fishing can be a major driver of coral‐to‐macroalgae regime shifts on tropical reefs. In many small‐scale coral reef fisheries, fishers target herbivorous fishes, which weaken resilience via reduced herbivory macroalgae then outcompete corals. Previous models explored the effects harvesting herbivores revealed hysteresis in herbivory–benthic state relationship results bistability coral‐ and macroalgae‐dominated states over some levels pressure, has been supported by empirical evidence. However, past have not accounted for functional differences among or how fisher selectivity different herbivore groups may alter benthic dynamics resilience. Here, we use dynamic model links differential two key to outcome competitive between macroalgae. We show depends only level but also types targeted fishers. Selectively browsing are capable consuming mature (e.g., unicornfish) increases precariousness moving system close tipping point. By contrast, selectively grazing preventing from becoming established parrotfishes) increase catch yields substantially more before point is reached. this lower with increasing effort comes at cost range bistable; makes shift triggered disturbance difficult impractical reverse. Our suggest management strategies fisheries should consider harvested coupled influence light trade‐off recovery following large disturbances.

Language: Английский

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The rise of octocoral forests on Caribbean reefs

Advances in marine biology, Journal Year: 2020, Volume and Issue: unknown, P. 361 - 410

Published: Jan. 1, 2020

Language: Английский

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