Nutrient connectivity via seabirds enhances dynamic measures of coral reef ecosystem function.

Cross-ecosystem nutrient fluxes can influence recipient food webs, including both static measures of structure and dynamic measures of function. However, a mechanistic basis for how nutrient subsidies affect both structure and function across multiple trophic levels is still lacking. Here, we investigate how nutrient subsidies provided by seabirds influence coral reefs, focusing on the link between primary producers and primary consumers.

Increased resilience and a regime shift reversal through repeat mass coral bleaching.

Ecosystems are substantially changing in response to ongoing climate change. For example, coral reefs have declined in coral dominance, with some reefs undergoing regime shifts to non-coral states. However, reef responses may vary through multiple heat stress events, with the rarity of long-term ecological datasets rendering such understanding uncertain.

Seabird nutrients increase coral calcification rates and boost reef carbonate production.

While excessive anthropogenic nutrient loads are harmful to coral reefs, natural nutrient flows can boost coral growth and reef functions. Here we investigate if seabird-derived nutrient subsidies benefit the growth of two dominant corals on lagoonal reefs, submassive Isopora palifera and corymbose Acropora vermiculata, and if enhanced colony-level calcification rates can increase reef-scale carbonate production. I.

Island restoration to rebuild seabird populations and amplify coral reef functioning.

Mobile organisms like seabirds can provide important nutrient flows between ecosystems, but this connectivity has been interrupted by the degradation of island ecosystems. Island restoration (via invasive species eradications and the restoration of native vegetation) can reestablish seabird populations and their nutrient transfers between their foraging areas, breeding colonies, and adjacent nearshore habitats. Its diverse benefits are making island restoration increasingly common and scalable to larger islands and whole archipelagos.

Species eradication for ecosystem restoration.

Many of the world's ecosystems are under unprecedented stress as human pressures have escalated to be a dominant driver of ecosystem composition and condition. Direct impacts such as agriculture, extraction, and development are impacting vast swathes of land and ocean, while the effects of human-caused climate change are felt even in the most remote parts of marine and terrestrial wildernesses. These impacts are resulting in changes ranging from ecosystem collapse or replacement to novel mixes of species due to temperature-driven range shifts.

Quantifying energy and nutrient fluxes in coral reef food webs.

The movement of energy and nutrients through ecological communities represents the biological 'pulse' underpinning ecosystem functioning and services. However, energy and nutrient fluxes are inherently difficult to observe, particularly in high-diversity systems such as coral reefs. We review advances in the quantification of fluxes in coral reef fishes, focusing on four key frameworks: demographic modelling, bioenergetics, micronutrients, and compound-specific stable isotope analysis (CSIA).

Reef-building corals farm and feed on their photosynthetic symbionts.

Coral reefs are highly diverse ecosystems that thrive in nutrient-poor waters, a phenomenon frequently referred to as the Darwin paradox. The energy demand of coral animal hosts can often be fully met by the excess production of carbon-rich photosynthates by their algal symbionts. However, the understanding of mechanisms that enable corals to acquire the vital nutrients nitrogen and phosphorus from their symbionts is incomplete.

Terrestrial invasive species alter marine vertebrate behaviour.

Human-induced environmental changes, such as the introduction of invasive species, are driving declines in the movement of nutrients across ecosystems with negative consequences for ecosystem function. Declines in nutrient inputs could thus have knock-on effects at higher trophic levels and broader ecological scales, yet these interconnections remain relatively unknown. Here we show that a terrestrial invasive species (black rats, Rattus rattus) disrupts a nutrient pathway provided by seabirds, ultimately altering the territorial behaviour of coral reef fish.

Seabird diversity and biomass enhance cross-ecosystem nutrient subsidies.

Mobile consumers are key vectors of cross-ecosystem nutrients, yet have experienced population declines which threaten their ability to fill this role. Despite their importance and vulnerability, there is little information on how consumer biodiversity, in addition to biomass, influences the magnitude of nutrient subsidies. Here, we show that both biomass and diversity of seabirds enhanced the provisioning of nutrients across tropical islands and coral reefs, but their relative influence varied across systems.

Natural nutrient subsidies alter demographic rates in a functionally important coral-reef fish.

By improving resource quality, cross-ecosystem nutrient subsidies may boost demographic rates of consumers in recipient ecosystems, which in turn can affect population and community dynamics. However, empirical studies on how nutrient subsidies simultaneously affect multiple demographic rates are lacking, in part because humans have disrupted the majority of these natural flows. Here, we compare the demographics of a sex-changing parrotfish (Chlorurus sordidus) between reefs where cross-ecosystem nutrients provided by seabirds are available versus nearby reefs where invasive, predatory rats have removed seabird populations.

Rat eradication restores nutrient subsidies from seabirds across terrestrial and marine ecosystems.

Biological invasions pose a threat to nearly every ecosystem worldwide. Although eradication programs can successfully eliminate invasive species and enhance native biodiversity, especially on islands, the effects of eradication on cross-ecosystem processes are unknown. On islands where rats were never introduced, seabirds transfer nutrients from pelagic to terrestrial and nearshore marine habitats, which in turn enhance the productivity, biomass, and functioning of recipient ecosystems.

Biodiversity increases ecosystem functions despite multiple stressors on coral reefs.

Positive relationships between biodiversity and ecosystem functioning (BEF) highlight the importance of conserving biodiversity to maintain key ecosystem functions and associated services. Although natural systems are rapidly losing biodiversity due to numerous human-caused stressors, our understanding of how multiple stressors influence BEF relationships comes largely from small, experimental studies. Here, using remote assemblages of coral reef fishes, we demonstrate strong, non-saturating relationships of biodiversity with two ecosystem functions: biomass and productivity.

Climatic and local stressor interactions threaten tropical forests and coral reefs.

Tropical forests and coral reefs host a disproportionately large share of global biodiversity and provide ecosystem functions and services used by millions of people. Yet, ongoing climate change is leading to an increase in frequency and magnitude of extreme climatic events in the tropics, which, in combination with other local human disturbances, is leading to unprecedented negative ecological consequences for tropical forests and coral reefs. Here, we provide an overview of how and where climate extremes are affecting the most biodiverse ecosystems on Earth and summarize how interactions between global, regional and local stressors are affecting tropical forest and coral reef systems through impacts on biodiversity and ecosystem resilience.

Synchronous biological feedbacks in parrotfishes associated with pantropical coral bleaching.

Biological feedbacks generated through patterns of disturbance are vital for sustaining ecosystem states. Recent ocean warming and thermal anomalies have caused pantropical episodes of coral bleaching, which has led to widespread coral mortality and a range of subsequent effects on coral reef communities. Although the response of many reef-associated fishes to major disturbance events on coral reefs is negative (e.

Seabird nutrient subsidies alter patterns of algal abundance and fish biomass on coral reefs following a bleaching event.

Cross-ecosystem nutrient subsidies play a key role in the structure and dynamics of recipient communities, but human activities are disrupting these links. Because nutrient subsidies may also enhance community stability, the effects of losing these inputs may be exacerbated in the face of increasing climate-related disturbances. Nutrients from seabirds nesting on oceanic islands enhance the productivity and functioning of adjacent coral reefs, but it is unknown whether these subsidies affect the response of coral reefs to mass bleaching events or whether the benefits of these nutrients persist following bleaching.

Predator effects on reef fish settlement depend on predator origin and recruit density.

During major life-history transitions, animals often experience high mortality rates due to predation, making predator avoidance particularly advantageous during these times. There is mixed evidence from a limited number of studies, however, regarding how predator presence influences settlement of coral-reef fishes and it is unknown how other potentially mediating factors, including predator origin (native vs. nonnative) or interactions among conspecific recruits, mediate the non-consumptive effects of predators on reef fish settlement.

Central-place foraging and ecological effects of an invasive predator across multiple habitats.

Cross-habitat foraging movements of predators can have widespread implications for predator and prey populations, community structure, nutrient transfer, and ecosystem function. Although central-place foraging models and other aspects of optimal foraging theory focus on individual predator behavior, they also provide useful frameworks for understanding the effects of predators on prey populations across multiple habitats. However, few studies have examined both the foraging behavior and ecological effects of nonnative predators across multiple habitats, and none has tested whether nonnative predators deplete prey in a manner predicted by these foraging models.

Patterns and Variation in Benthic Biodiversity in a Large Marine Ecosystem.

While there is a persistent inverse relationship between latitude and species diversity across many taxa and ecosystems, deviations from this norm offer an opportunity to understand the conditions that contribute to large-scale diversity patterns. Marine systems, in particular, provide such an opportunity, as marine diversity does not always follow a strict latitudinal gradient, perhaps because several hypothesized drivers of the latitudinal diversity gradient are uncorrelated in marine systems. We used a large scale public monitoring dataset collected over an eight year period to examine benthic marine faunal biodiversity patterns for the continental shelf (55-183 m depth) and slope habitats (184-1280 m depth) off the US West Coast (47°20'N-32°40'N).

Evaluating Temporal Consistency in Marine Biodiversity Hotspots.

With the ongoing crisis of biodiversity loss and limited resources for conservation, the concept of biodiversity hotspots has been useful in determining conservation priority areas. However, there has been limited research into how temporal variability in biodiversity may influence conservation area prioritization. To address this information gap, we present an approach to evaluate the temporal consistency of biodiversity hotspots in large marine ecosystems.

Density-dependent growth in invasive Lionfish (Pterois volitans).

Direct demographic density dependence is necessary for population regulation and is a central concept in ecology, yet has not been studied in many invasive species, including any invasive marine fish. The red lionfish (Pterois volitans) is an invasive predatory marine fish that is undergoing exponential population growth throughout the tropical western Atlantic. Invasive lionfish threaten coral-reef ecosystems, but there is currently no evidence of any natural population control.