Biology subjects

Pandolfi, J. M.

Publications and source records attributed to Pandolfi, J. M..

3 recordsLinked to original sources

bioRxiv2022

High-latitude marginal reefs support fewer but bigger corals than their tropical counterparts

AimDespite the awareness that climate change impacts are typically detrimental to tropical coral reefs, the effect of increasing environmental stress and variability on the population size structure of coral species remains poorly understood. This gap in knowledge limits our ability to effectively conserve coral reef ecosystems because size specific dynamics are rarely incorporated. Our aim is to quantify variation in the size structure of coral populations along a tropical-to-subtropical environmental gradient. Location20 coral populations along a latitudinal gradient on the east coast of Australia ([~]23{degrees}S to 30{degrees}S). Time PeriodBetween 2010 and 2018. Major taxa studiedScleractinian corals. MethodsWe apply two methods to quantify the relationship between environmental covariates and coral population size structure along a latitudinal environmental gradient. First, we use linear regression with summary statistics, such as median size as response variables; a method frequently favoured by ecologists. The second method is compositional functional regression, a novel method using entire size-frequency distributions as response variables. We then predict coral population size structure with increasing environmental stress and variability. ResultsCompared to tropical reefs, we find fewer but larger coral colonies in marginal reefs, where environmental conditions are more variable and stressful for corals in the former. Our model predicts that coral populations may become gradually dominated by larger colonies (> 148 cm2) with increasing environmental stress. Main conclusionsWith increasing environmental stress and variability, we can expect shifts in coral population size structure towards more larger colonies. Fewer but bigger corals suggest low survival, slow growth, and poor recruitment. This finding is concerning for the future of coral reefs as it implies populations may have low recovery potential from disturbances. We highlight the importance and usefulness of continuously monitoring changes to population structure over large spatial scales. Data availabilityData is supplied in the supplementary information, or upon request. Once accepted for publication it will be made openly available on Dryad.

ecology↗

bioRxiv2021

Coral assemblages at higher latitudes favour short-term potential over long-term performance

The persistent exposure of coral communities to more variable abiotic regimes is assumed to augment their resilience to future climatic variability. Yet, while the determinants of coral population resilience across species remain unknown, we are unable to predict the winners and losers across reef ecosystems exposed to increasingly variable conditions. Using annual surveys of 3171 coral individuals across Australia and Japan (2017-2019), we explore spatial variation across the short- and long-term dynamics of competitive, stress-tolerant, and weedy assemblages to evaluate how thermal variability mediates the structural composition of coral communities. We illustrate how, by promoting short-term potential over long-term performance, coral assemblages can reduce their vulnerability to stochastic environments. However, compared to stress-tolerant, and weedy assemblages, competitive coral taxa display a reduced capacity for elevating their short-term potential. Accordingly, future climatic shifts threaten the structural complexity of coral assemblages in variable environments, emulating the degradation expected across global tropical reefs.

ecology↗

bioRxiv2020

The rise and fall of novel ecological communities

Local and global environmental change is transforming ecological assemblages into new configurations, resulting in ecosystems with novel communities. Here we develop a robust methodology for the identification of novel communities, examine patterns in their natural chance of occurrence, and quantify the probability of local extinction, emigration, local origination and immigration in transitions to and from novel communities. Using a global dataset of Cenozoic marine plankton communities, we found the probability of local extinction, origination and emigration during transitions to a novel community increased up to four times that of background community changes, with the probability of species loss about equal to that of species gain. Although rare, once a novel community state emerged, the chance of shifting into another novel community state was five times greater than expected by chance. Thus, for marine planktonic communities at 100K year time scales, novel communities are particularly sensitive to further extinctions and community shift. One Sentence SummaryOnce developed, novel ecological communities face increased susceptibility to further shifts in species composition, with heightened extinction risk.

ecology↗