High germline mutation rates, but not extreme population outbreaks, influence genetic diversity in a keystone coral predator.

Lewontin's paradox, the observation that levels of genetic diversity (π) do not scale linearly with census population size (Nc) variation, is an evolutionary conundrum. The most extreme mismatches between π and Nc are found for highly abundant marine invertebrates. Yet, the influences of new mutations on π relative to extrinsic processes such as Nc fluctuations are unknown.

Induction of larval settlement in crown-of-thorns starfish is not mediated by conspecific cues.

Population irruptions of crown-of-thorns starfish (COTS; Acanthaster spp.) remain a major cause of coral reef degradation throughout the Pacific and Indian Oceans and are inherently modulated by larval settlement and recruitment success. Gregarious larval settlement, as exhibited by many other ecologically important marine invertebrates, can catalyse population growth and replenishment.

Life-stage specificity and cross-generational climate effects on the microbiome of a tropical sea urchin (Echinodermata: Echinoidea).

Microbes play a critical role in the development and health of marine invertebrates, though microbial dynamics across life stages and host generations remain poorly understood in most reef species, especially in the context of climate change. Here, we use a 4-year multigenerational experiment to explore microbe-host interactions under the Intergovernmental Panel on Climate Change (IPCC)-forecast climate scenarios in the rock-boring tropical urchin Echinometra sp. A.

Impacts of ocean warming on echinoderms: A meta-analysis.

Rising ocean temperatures are threatening marine species and populations worldwide, and ectothermic taxa are particularly vulnerable. Echinoderms are an ecologically important phylum of marine ectotherms and shifts in their population dynamics can have profound impacts on the marine environment. The effects of warming on echinoderms are highly variable across controlled laboratory-based studies.

Settlement cue selectivity by larvae of the destructive crown-of-thorns starfish.

Population irruptions of crown-of-thorns starfish (COTS) cause extensive degradation of coral reefs, threatening the structure and function of these important ecosystems. For population irruptions to initiate and spread, large numbers of planktonic larvae have to successfully transition into their benthic life-history stage (i.e.

Developing an effective marine eDNA monitoring: eDNA detection at pre-outbreak densities of corallivorous seastar (Acanthaster cf. solaris).

Outbreaks of the corallivorous Crown-of-Thorns Seastar (CoTS) Acanthaster cf. solaris contribute significantly to coral reef loss. Control of outbreaks is hampered because standard monitoring techniques do not detect outbreaks at early (low density) stages, thus preventing early intervention.

DNA-Based Detection and Patterns of Larval Settlement of the Corallivorous Crown-of-Thorns Sea Star ( sp.).

AbstractPopulation irruptions of the western Pacific crown-of-thorns sea star ( sp.) are a perennial threat to coral reefs and may be initiated by fluctuations in reproductive or settlement success. However, the processes dictating their early life history, particularly larval settlement, remain poorly understood given limitations in sampling larvae and newly settled juveniles in the field.

Knowledge Gaps in the Biology, Ecology, and Management of the Pacific Crown-of-Thorns Sea Star sp. on Australia's Great Barrier Reef.

AbstractCrown-of-thorns sea stars ( sp.) are among the most studied coral reef organisms, owing to their propensity to undergo major population irruptions, which contribute to significant coral loss and reef degradation throughout the Indo-Pacific. However, there are still important knowledge gaps pertaining to the biology, ecology, and management of sp.

Combined effects of climate change and the herbicide diuron on the coral Acropora millepora.

The Great Barrier Reef (GBR) is threatened by climate change and local pressures, including contaminants in nearshore habitats. This study investigated the combined effects of a GBR-relevant contaminant, the herbicide diuron, under current and two future climate scenarios on the coral Acropora millepora. All physiological responses tested (effective quantum yield (ΔF/Fm'), photosynthesis, calcification rate) were negatively affected with increasing concentrations of diuron.

Cross-generational response of a tropical sea urchin to global change and a selection event in a 43-month mesocosm study.

Long-term experimental investigations of transgenerational plasticity (TGP) and transgenerational acclimatization to global change are sparse in marine invertebrates. Here, we test the effect of ocean warming and acidification over a 25-month period of Echinometra sp. A sea urchins whose parents were acclimatized at ambient or one of two near-future (projected mid and end of the 21st century) climate scenarios for 18 months.

Climate change doubles sedimentation-induced coral recruit mortality.

Coral reef replenishment is threatened by global climate change and local water-quality degradation, including smothering of coral recruits by sediments generated by anthropogenic activities. Here we show that the ability of Acropora millepora recruits to remove sediments diminishes under future climate conditions, leading to increased mortality. Recruits raised under future climate scenarios for fourteen weeks (highest treatment: +1.

Cross-generational effects of climate change on the microbiome of a photosynthetic sponge.

Coral reefs are facing increasing pressure from rising seawater temperatures and ocean acidification. Sponges have been proposed as possible winners in the face of climate change; however, little is known about the mechanisms underpinning their predicted tolerance. Here we assessed whether microbiome-mediated cross-generational acclimatization could enable the photosynthetic sponge Carteriospongia foliascens to survive under future climate scenarios.

Acclimation history modulates effect size of calcareous algae (Halimeda opuntia) to herbicide exposure under future climate scenarios.

Tropical marine habitat-builders such as calcifying green algae can be susceptible to climate change (warming and acidification). This study evaluated the cumulative effects of ocean warming (OW), ocean acidification (OA) and the herbicide diuron on the calcifying green algae Halimeda opuntia. We also assessed the influence of acclimation history to experimental climate change conditions on physiological responses.

Adjusting Tropical Marine Water Quality Guideline Values for Elevated Ocean Temperatures.

Increased frequency of summer heatwaves and poor water quality are two of the most prevalent and severe pressures faced by coral reefs. While these pressures often co-occur, their potential risks to tropical marine species are usually considered independently. Here, we extended the application of multisubstance-Potentially Affected Fraction (ms-PAF) to a nonchemical stressor, elevated sea surface temperature.

Little evidence of adaptation potential to ocean acidification in sea urchins living in "Future Ocean" conditions at a CO vent.

Ocean acidification (OA) can be detrimental to calcifying marine organisms, with stunting of invertebrate larval development one of the most consistent responses. Effects are usually measured by short-term, within-generation exposure, an approach that does not consider the potential for adaptation. We examined the genetic response to OA of larvae of the tropical sea urchin sp.

Losing a winner: thermal stress and local pressures outweigh the positive effects of ocean acidification for tropical seagrasses.

Seagrasses are globally important coastal habitat-forming species, yet it is unknown how seagrasses respond to the combined pressures of ocean acidification and warming of sea surface temperature. We exposed three tropical species of seagrass (Cymodocea serrulata, Halodule uninervis, and Zostera muelleri) to increasing temperature (21, 25, 30, and 35°C) and pCO (401, 1014, and 1949 μatm) for 7 wk in mesocosms using a controlled factorial design. Shoot density and leaf extension rates were recorded, and plant productivity and respiration were measured at increasing light levels (photosynthesis-irradiance curves) using oxygen optodes.

Crown-of-Thorns Sea Star Acanthaster cf. solaris Has Tissue-Characteristic Microbiomes with Potential Roles in Health and Reproduction.

Outbreaks of coral-eating crown-of-thorns sea stars (CoTS; species complex) cause substantial coral loss; hence, there is considerable interest in developing prevention and control strategies. We characterized the microbiome of captive CoTS and assessed whether dysbiosis was evident in sea stars during a disease event. Most tissue types had a distinct microbiome.

Optimum Temperatures for Net Primary Productivity of Three Tropical Seagrass Species.

Rising sea water temperature will play a significant role in responses of the world's seagrass meadows to climate change. In this study, we investigated seasonal and latitudinal variation (spanning more than 1,500 km) in seagrass productivity, and the optimum temperatures at which maximum photosynthesis and net productivity (for the leaf and the whole plant) occurs, for three seagrass species (, and ). To obtain whole plant net production, photosynthesis, and respiration rates of leaves and the root/rhizome complex were measured using oxygen-sensitive optodes in closed incubation chambers at temperatures ranging from 15 to 43°C.

Model fit versus biological relevance: Evaluating photosynthesis-temperature models for three tropical seagrass species.

When several models can describe a biological process, the equation that best fits the data is typically considered the best. However, models are most useful when they also possess biologically-meaningful parameters. In particular, model parameters should be stable, physically interpretable, and transferable to other contexts, e.

In situ developmental responses of tropical sea urchin larvae to ocean acidification conditions at naturally elevated pCO2 vent sites.

Laboratory experiments suggest that calcifying developmental stages of marine invertebrates may be the most ocean acidification (OA)-sensitive life-history stage and represent a life-history bottleneck. To better extrapolate laboratory findings to future OA conditions, developmental responses in sea urchin embryos/larvae were compared under ecologically relevant in situ exposures on vent-elevated pCO and ambient pCO coral reefs in Papua New Guinea. Echinometra embryos/larvae were reared in meshed chambers moored in arrays on either venting reefs or adjacent non-vent reefs.

Ocean acidification has little effect on developmental thermal windows of echinoderms from Antarctica to the tropics.

As the ocean warms, thermal tolerance of developmental stages may be a key driver of changes in the geographical distributions and abundance of marine invertebrates. Additional stressors such as ocean acidification may influence developmental thermal windows and are therefore important considerations for predicting distributions of species under climate change scenarios. The effects of reduced seawater pH on the thermal windows of fertilization, embryology and larval morphology were examined using five echinoderm species: two polar (Sterechinus neumayeri and Odontaster validus), two temperate (Fellaster zelandiae and Patiriella regularis) and one tropical (Arachnoides placenta).

Effects of High Dissolved Inorganic and Organic Carbon Availability on the Physiology of the Hard Coral Acropora millepora from the Great Barrier Reef.

Coral reefs are facing major global and local threats due to climate change-induced increases in dissolved inorganic carbon (DIC) and because of land-derived increases in organic and inorganic nutrients. Recent research revealed that high availability of labile dissolved organic carbon (DOC) negatively affects scleractinian corals. Studies on the interplay of these factors, however, are lacking, but urgently needed to understand coral reef functioning under present and near future conditions.

Light Levels Affect Carbon Utilisation in Tropical Seagrass under Ocean Acidification.

Under future ocean acidification (OA), increased availability of dissolved inorganic carbon (DIC) in seawater may enhance seagrass productivity. However, the ability to utilise additional DIC could be regulated by light availability, often reduced through land runoff. To test this, two tropical seagrass species, Cymodocea serrulata and Halodule uninervis were exposed to two DIC concentrations (447 μatm and 1077 μatm pCO2), and three light treatments (35, 100, 380 μmol m(-2) s(-1)) for two weeks.

Influence of local habitat on the physiological responses of large benthic foraminifera to temperature and nutrient stress.

Large benthic foraminifera (LBF) are important for reef sediment formation, but sensitive to elevated temperature and nutrients. However, it is possible that conspecific foraminifera living in different reef sites present divergent response to environmental shifts. We investigated how populations of Amphistegina lobifera from reef sites located along a temperature and nutrient gradient of the northern Great Barrier Reef respond and acclimate to elevated temperature and nitrate under lab-controlled conditions.

Echinometra sea urchins acclimatized to elevated pCO2 at volcanic vents outperform those under present-day pCO2 conditions.

Rising atmospheric CO2 concentrations will significantly reduce ocean pH during the 21st century (ocean acidification, OA). This may hamper calcification in marine organisms such as corals and echinoderms, as shown in many laboratory-based experiments. Sea urchins are considered highly vulnerable to OA.