Coral reefs are among the richest ecosystems on earth in terms of biodiversity and productivity, yet are at high risk of habitat degradation and species extinction from climate change and other anthropogenic influences. Resilience refers to the maintenance of key physiological and ecological functions following disturbances, which can be studied from the scale of individual organisms, populations, to entire ecosystems. Ecological factors that can negatively impact coral reefs include increased water temperatures, increased water acidification, overfishing, nutrient pollution, sedimentation, and impacts of climate variability such as the El Niño-Southern Oscillation. On the individual organism and population scale, resilience occurs through eco-physiological plasticity and/or gene expression and regulation during stress, and the capacity for resilience varies greatly across species and populations. Mechanisms related to resilience at this scale include response traits to environmental changes, population growth rates, and genetic diversity that can measured at both short-term and long-term responses to environmental shifts. Other ecosystem attributes that contribute to resilience includes connectivity, temporal and spatial variability, and functional redundancy. Oceanographic parameters, including water currents at small, meso-, and large scales, tidal force, upwelling, and seasonal rainfall patterns influence marine habitats that may impact the resilience of local organisms. These abiotic parameters can alter nutrient availability, stratification, irradiance levels, the degree of larval retention or dispersal, productivity, and numerous other ecological factors. The high temporal and spatial variability of oceanographic patterns often means that locations must be studied over several years before assumptions can be made regarding resilience of coral reef ecosystems. Our ability to understand resilience is enhanced with modern technology, including oceanographic sensing instrumentation and molecular genetics. Many reef-building corals and other reef organisms host endosymbiotic algae, a particular topic of interest among coral reef researchers. This host-symbiont relationship creates a complex of nutrient cycling and is recognized to impact resilience on the individual organism and population scale. Advances in molecular genetics and instrumentation such as flow cytometers have helped researchers understand these relationships in recent years. With documentation of worldwide coral reef habitat degradation spanning decades, competitive research grants continue to fund studies across both tropical and temperate reef ecosystems, and the number of coral reef-related research projects increases. Thus, we expect that the research presented in this session will highlight advancements in our understanding of resilience in coral reef ecosystems across many scales. This includes the species, population, and community levels, as well as across spatial and temporal variation.
Lead Organizer: Star Dressler, University of Guam (dresslerc@gotritons.uog.edu)
Co-organizers:
Atsushi Fujimura, University of Guam (fujimuraa@triton.uog.edu)
Presentations
03:00 PM
Small-scale spatial variation in demographic performance of Acropora cervicornis coral outplants in Culebra, Puerto Rico (6630)
Primary Presenter: Patria Aponte-Marcano, Ana G. Mendez University (patriaap@gmail.com)
Acropora cervicornis is a threatened coral species considered one of the most important Caribbean reef-building corals. Due to its critical status and ecological importance, many restoration efforts focus on its population recovery. Outplanting nursery-reared corals is a strategy to restore populations, but there is an urgent need to measure variations in demographic performance between small-scale spatial variations, in order to enhance site selection for restoration activities. Many restoration efforts evaluate coral demography between time and inter-sites, but less is known about the implications of intra-site spatial variation. In this study, nursery-reared fragments of A. cervicornis were outplanted to the reef substrate to assess demographic performance in small-scale spatial variations. We measured survival, growth, productivity, branch production, size, height, and coral cover for a period of 2 years. At the end of the study, 85% of the corals survived. A. cervicornis outplants showed mean growth rates intra-site variations ranging from 40.3 ± 44.6 (± SD) cm/year to 10.5 ± 17.0 (± SD) cm/year. Mean productivity rates ranged from 1.76 ± 1.89 (± SD) cm/year to 0.71 ± 0.95 (± SD) cm/year. Coral growth decreased during the second year post-outplanting, with 59.5 % of outplants showing negative growth. Such a reduction could be associated with predation by the fireworm Hermodice carunculata. Despite this negative effect, there has been a significant shift in coral size and height of the restored populations towards large colonies. After two years of restoration activities, mean colony size and height increased by 58.1% and 27.4% respectively. However, coral cover dropped by 2.9%. We conclude that A. cervicornis demographic success differs significantly between time and intra-site spatial variations.
03:15 PM
CARIBBEAN CORAL RESILIENCE THROUGH THE NATURAL RESOURCE MANAGEMENT LENSE: STONY CORAL TISSUE LOSS DISEASE (4925)
Primary Presenter: Courtney Tierney, US Virgin Islands Department of Planning and Natural Resources (chtierne@eckerd.edu)
In January 2019, coral reefs of the US Virgin Islands were faced with yet another threat. Stony Coral Tissue Loss Disease (SCTLD) was present and spreading quickly throughout the territory. Natural resource managers jumped into action to create standard operating procedures and management plans in the face of this novel disturbance while researchers worked overtime to help inform decisions. Strike Team divers were dispatched to hand-treat diseased corals weekly to slow the spread. As the epidemic has gradually turned into an endemic, managers have now shifted their focus to protecting the resilience of current and future coral reefs around the territory. A database of highly susceptible species’ geocoordinates is maintained to keep track of the last survivors of the disease. Collaborative rescue missions are carried out to collect and bank fragments of these resilient colonies in the hopes of using their offspring for future restoration. USVI coral practitioners have created a ten-year restoration plan to bring reefs back to pre-disease level functionality. Diving into the outbreak, research, response challenges and successes, and the recovery plans for a disturbance such as disease provides insight to understanding the resilience of Caribbean coral reefs.
03:30 PM
GENOMIC SIGNATURES OF DISEASE RESISTANCE IN ENDANGERED STAGHORN CORALS (4927)
Primary Presenter: Steve Vollmer, Northeastern University (s.vollmer@northeastern.edu)
White Band Disease has caused unprecedented mortality in the Caribbean <em>Acropora</em> corals and resulted in their US Endangered Species listing. Highly disease resistant <em>A. cervicornis</em> genotypes exist, but we lack a basic understanding of the genetic underpinnings of coral disease resistance. Using transmission experiments and whole genome sequencing of 74 <em>A. cervicornis</em> genotypes from Florida and Panama, we identify ten genomic regions and 73 single-nucleotide polymorphisms (SNPs) that are strongly associated with disease resistance that includes in five genes involve coral immunity and pathogen detection. Polygenic scores calculated from our top 10 genomic loci demonstrate that simple genetic screens can accurately predict which corals will be highly disease resistant versus highly susceptible and then select highly disease resistant corals for nursery stocks and on-going restoration efforts.
03:45 PM
THE INFLUENCE OF PCO2 VARIABILITY ON CORAL RESILIENCE UNDER GLOBAL CHANGE (5486)
Primary Presenter: Kristen Brown, University of Pennsylvania (kristen.brown@uq.edu.au)
Naturally variable habitats or extreme environments provide a glimmer of hope that climate-resilient coral populations exist on coral reefs worldwide. Yet, the mechanisms by which corals have acclimated to current variability and whether this will allow them to resist future changes remains poorly understood. Here, we examined the impact of pCO2 variability on the reef-building coral Pocillopora damicornis originating from reefs with contrasting environmental histories (variable versus stable) following reciprocal exposure to stable (218 ± 9) or variable (911 ± 31) diel pCO2 amplitude (μatm) in aquaria over eight weeks. We found that corals from the variable habitat exhibited less intracellular pH (pHi) acidosis and faster pHi recovery rates in response to experimental acidification stress than corals originating from the stable reef slope, suggesting environmental memory gained from lifelong exposure to pCO2 variability led to an improved ability to regulate acid–base homeostasis. We further explored changes in biomineralization using scanning electron microscopy (SEM) and gene expression via TagSeq, with preliminary results indicating greater corallite diameter and frontloaded genes for stress in P. damicornis originating from variable habitats. These results suggest that prior exposure to pCO2 variability may promote more acidification-resilient coral populations in a changing climate.
04:00 PM
BIOGEOCHEMICAL PROCESSES AFFECTING OCEAN ACIDIFICATION IN A GULF OF MEXICO CORAL REEF (6001)
Primary Presenter: Allison Savoie, Texas A&M University (allison.m.savoie@tamu.edu)
The Flower Garden Banks National Marine Sanctuary (FGBNMS) includes 17 banks, topped by tropical and mesophotic corals, located ~200 km offshore on the edge of the continental shelf in the northern Gulf of Mexico. This area serves as a valuable habitat for fisheries and threatened/endangered species of manta rays, sea turtles, and corals. Because ocean acidification slows coral reef growth and enhances erosion and dissolution, this study investigates local and global drivers of acidification at the FGBNMS, which occur in a region with enhanced acidification rates relative to the open ocean. Acidification in the FGBNMS can be influenced by upwelling from deeper waters, freshwater runoff from land, Loop Current Eddies, hurricanes, and subsurface hypoxia. Data were collected within the FGBNMS from 2015 to 2019, which includes two major hurricanes, several freshwater discharge events, and possible upwelling of deep water onto the reefs. In the subsurface, from ~25-125m, acidification was enhanced in 2016 compared to 2015 and 2017. 2015-2017 had comparable total alkalinity (TA) at these depths, but subsurface dissolved inorganic carbon (DIC) and partial pressure of carbon dioxide were higher, and aragonite saturation state (Ωar) and pH were lower in 2016. The 2016 enhanced subsurface acidification is likely due to an upwelling event that led to colder, more acidic waters reaching the depth of the coral reefs (~16-46 m). Data from 2018 & 2019 are being analyzed and the potential impacts of loop current eddies and hurricanes will also be investigated across the 5-year dataset.
04:15 PM
Do they resist or recover? Impacts of global warming on the demographic resilience of Mediterranean coralligenous populations. (7089)
Primary Presenter: Pol Capdevila, Universitat de Barcelona (pcapdevila.pc@gmail.com)
The effects of climate change are now more pervasive than ever. Marine ecosystems have been particularly impacted by climate change, with many being on the brink of collapse. This is the case for Mediterranean coralligenous assemblages, a complex and highly diverse marine ecosystem that has suffered dramatic declines over the past decade due to rising temperatures. To halt the impacts of climate change the international efforts to reduce carbon emissions have never been so ambitious. However, even in the most optimistic CO2 emission scenarios, the planet will continue to warm and experience the effects of climate change over the coming decades. For this reason, understanding the resilience of these key habitats to warmer temperatures is crucial to predict their viability under future climatic conditions. Here, we will present our work exploring the resilience of Mediterranean coralligenous populations from a long-term marine protected area. More specifically, we use demographic data for the key coralligenous species Paramuricea clavata to quantify its capacity to resist and recover from future disturbances, comparing contemporary data against populations from the early 2000s. Overall, our results show that the demographic resilience of P. clavata populations has decreased dramatically, through a sharp drop in their resistance to disturbances. These findings confirm that future climatic conditions will make these populations even more vulnerable to further perturbations, highlighting the importance of limiting the impacts of other threats to them.
SS115A Resilience in Coral Reef Ecosystems
Description
Time: 3:00 PM
Date: 9/6/2023
Room: Sala Menorca A