Biology subjects

McWilliam, M.

Publications and source records attributed to McWilliam, M..

3 recordsLinked to original sources

bioRxiv2026

Coral reef ecosystem functions in a human-dominated world

The metabolic processes sustaining coral reefs, from carbonate and primary production to secondary production, remain poorly integrated and rarely quantified simultaneously at global scales. This hampers our ability to predict global responses to accelerating human pressures and manage coral reef functioning. Using metabolic scaling and bioenergetic models applied to surveys from 1,100 reefs worldwide, we provide a global, standardized quantification of 14 ecosystem functions spanning benthic (corals and algae) and fish communities. Our analysis reveals a continuous functional spectrum of global coral reefs organized along four dominant axes: 1) primary production, 2) calcification and habitat structure, 3) secondary biomass production and consumption, and 4) biomass turnover. Functions mediated by fish and benthic communities show weak associations at the global scale rather than tight coupling. Climate stressors reduced calcification and local human impacts lowered secondary production. Yet these directional effects unfolded against a backdrop of substantial natural variability in reef functional configurations, such that heavily and minimally impacted reefs overlap substantially in the global functional space. Temporal analyses across three representative reef systems further revealed that functional trajectories following disturbance are context-dependent, with no universal pattern of recovery across locations. This continuous and context-dependent functional spectrum challenges the notion of universal functional benchmarks and supports locally tailored conservation strategies.

ecology↗

bioRxiv2025

Demographic insights for coral restoration

O_LICoral reef decline has prompted a global surge in reef restoration initiatives. The success of initiatives that aim to sustain coral populations or assemblages will depend on demographic principles. Restoration strategies generally follow two demographic pathways: supplemental approaches, which increase population numbers through the repeated addition of recruits, fragments, or adults, without fundamentally altering long-term population dynamics; and structural approaches, which enhance vital rates-growth, survival, or reproduction- through changes that modify the demographic processes governing population growth on a sustained basis, either extrinsically (e.g., herbivory, habitat protection) or intrinsically (e.g., assisted evolution). Some interventions, such as supplemental feeding, may temporarily improve vital rates but still function as supplemental approaches because benefits persist only while interventions continue. C_LIO_LIWe synthesized 28 coral matrix population models spanning morphologically diverse coral species from the Caribbean, Hawaii, and the Great Barrier Reef to quantify supplemental and structural changes needed to increase population growth. C_LIO_LIResults highlight two consistent demographic leverage points for which population growth was most sensitive: (1) survival of reproductive adults and (2) successful recruitment. Improving adult survival or recruitment by 20% through structural means produced a 5% increase in population growth rate across population on average, assuming the whole population was affected. By contrast through supplemental means, the same increase required [~]100 recruit outplants or 5-10 adult outplants per 1,000 individuals in a population annually. For large populations typical of restoration targets (105-107 individuals), this translates to 103 adult and 104 recruit outplants per year--levels rarely logistically or economically feasible. C_LIO_LIThese findings yield two key implications. First, supplemental interventions are inefficient for large populations and demand sustained, large-scale effort, even when they temporarily enhance growth or survival. Second, strategies enhancing vital rates across broad geographic areas represent the most effective means of boosting coral abundance, including habitat protection, alleviation of environmental stressors, and interventions which promote long-term survival and recruitment. Our demographic framework underscores that if the restoration goal is sustained increases in coral cover, success depends less on repeated supplements and more on interventions that produce lasting improvements in vital rates. C_LI

ecology↗

bioRxiv2021

Selecting species for restoration in foundational assemblages

O_LIHumans have long sought to restore species, but little attention has been directed at how to best select a subset of foundation species for maintaining rich assemblages that support ecosystems, like coral reefs and rainforests that are increasingly threatened by environmental change. C_LIO_LIWe propose a two-part hedging approach that selects optimized sets of species for restoration. The first part acknowledges that biodiversity supports ecosystem functions and services, and so it takes precaution against loss by ensuring an even spread of phenotypic traits. The second part maximizes species and ecosystem persistence by weighting species based on characteristics that are known to improve ecological persistence--e.g., abundance, species range and tolerance to environmental change. C_LIO_LIUsing existing phenotypic trait and ecological characteristic data for reef building corals, we identified sets of ecologically persistent species by examining marginal returns in occupancy of phenotypic trait space. We compared optimal sets of species with those from the worlds southern-most coral reef which naturally harbors low coral diversity to show these occupy much of the trait space. Comparison with an existing coral restoration program indicated that current corals used for restoration only cover part of the desired trait space and may be improved by including species with different traits. C_LIO_LISynthesis and applications. While there are many possible criteria for selecting species for restoration, the approach proposed here addresses the need to insure against unpredictable losses of ecosystem services by focusing on a wide range of phenotypic traits and ecological characteristics. Furthermore, the flexibility of the approach enables the functional goals of restoration to vary depending on environmental context, stakeholder values, and the spatial and temporal scales at which meaningful impacts can be achieved. C_LI

ecology↗