Acropora Intermedia Research Articles

Asymmetric physiological response of a reef-building coral to pulsed versus continuous addition of inorganic nutrients

Coral reefs, especially those located near-shore, are increasingly exposed to anthropogenic, eutrophic conditions that are often chronic. Yet, corals under unperturbed conditions may frequently receive natural and usually temporary nutrient supplementation through biological sources such as fishes. We compared physiological parameters indicative of long- and short-term coral health (day and night calcification, fragment surface area, productivity, energy reserves, and tissue stoichiometry) under continuous and temporary nutrient enrichment. The symbiotic coral Acropora intermedia was grown for 7 weeks under continuously elevated (press) levels of ammonium (14 µmol L−1) and phosphate (10 µmol L−1) as separate and combined treatments, to discern the individual and interactive nutrient effects. Another treatment exposed A. intermedia twice-daily to an ammonium and phosphate pulse of the same concentrations as the press treatments to simulate natural biotic supplementation. Press exposure to elevated ammonium or phosphate produced mixed effects on physiological responses, with little interaction between the nutrients in the combined treatment. Overall, corals under press exposure transitioned resources away from calcification. However, exposure to nutrient pulses often enhanced physiological responses. Our findings indicate that while continuous nutrient enrichment may pose a threat to coral health, episodic nutrient pulses that resemble natural nutrient supplementation may significantly benefit coral health and physiology.

Heat stress decreases the diversity, abundance and functional potential of coral gas emissions.

Terrestrial ecosystems emit large quantities of biogenic volatile organic compounds (BVOCs), many of which play important roles in abiotic stress responses, pathogen and grazing defences, inter- and intra-species communications, and climate regulation. Conversely, comparatively little is known about the diversity and functional potential of BVOCs produced in the marine environment, especially in highly productive coral reefs. Here we describe the first 'volatilomes' of two common reef-building corals, Acropora intermedia and Pocillopora damicornis, and how the functional potential of their gaseous emissions is altered by heat stress events that are driving rapid deterioration of coral reef ecosystems worldwide. A total of 87 BVOCs were detected from the two species and the chemical richness of both coral volatilomes-particularly the chemical classes of alkanes and carboxylic acids-decreased during heat stress by 41% and 62% in A. intermedia and P. damicornis, respectively. Across both coral species, the abundance of individual compounds changed significantly during heat stress, with the majority (>86%) significantly decreasing compared to control conditions. Additionally, almost 60% of the coral volatilome (or 52 BVOCs) could be assigned to four key functional groups based on their activities in other species or systems, including stress response, chemical signalling, climate regulation and antimicrobial activity. The total number of compounds assigned to these functions decreased significantly under heat stress for both A. intermedia (by 35%) and P. damicornis (by 64%), with most dramatic losses found for climatically active BVOCs in P. damicornis and antimicrobial BVOCs in A. intermedia. Together, our observations suggest that future heat stress events predicted for coral reefs will reduce the diversity, quantity and functional potential of BVOCs emitted by reef-building corals, potentially further compromising the healthy functioning of these ecosystems.

Growth rate and survivorship of Acropora sp. fragments that transplanted on the artificial substrate made from fly ash and bottom ash

The purpose of this research is to analyze the success the transplantation method using kerbstone media from blocks made of coal waste (fly ash and bottom ash) from Thermal Power Station (PLTU). The research was done from March to August 2018 in the waters of Paiton, Probolinggo, East Java, Indonesia. The method applied in this research a 7-block design with “H” formation for every module. The coral fragments of Acropora formosa, Acropora pulchra, Acropora intermedia, and Acropora gomezi was 10 cm in average size with 30 repetitions for each size. The average growth rate showed different values during five months of research since the transplantation was done. Acropora formosa had the highest growth rate of 1.958 cm/month. Acropora intermedia 1.730 cm/month, Acropora pulchra 0.958 cm/month, and 0.756 cm/month for Acropora gomezi. By using Kruskal Wallis test for data analysing, obtained a survival rate of over 80% for all types, with Acropora formosa as the highest (92.3%) and Acropora gomezi as the lowest (82.61%). Therefore, kerbstone is considered feasible as a growth media for the coral reef as an effort to support CTI (Coral Triangle Initiative) program in overcoming global warming as an innovation.

Differential Occupation of Available Coral Hosts by Coral-Dwelling Damselfish (Pomacentridae) on Australia’s Great Barrier Reef

Associations between habitat-forming, branching scleractinian corals and damselfish have critical implications for the function and trophic dynamics of coral reef ecosystems. This study quantifies how different characteristics of reef habitat, and of coral morphology, determine whether fish occupy a coral colony. In situ surveys of aggregative damselfish–coral associations were conducted at 51 different sites distributed among 22 reefs spread along >1700 km of the Great Barrier Reef, to quantify interaction frequency over a large spatial scale. The prevalence of fish–coral associations between five damselfish (Chromis viridis, Dascyllus aruanus, Dascyllus reticulatus, Pomacentrus amboinensis and Pomacentrus moluccensis) and five coral species (Acropora spathulata, Acropora intermedia, Pocillopora damicornis, Seriatopora hystrix, and Stylophora pistillata) averaged ~30% across all corals, but ranged from <1% to 93% of small branching corals occupied at each site, depending on reef exposure levels and habitat. Surprisingly, coral cover was not correlated with coral occupancy, or total biomass of damselfish. Instead, the biomass of damselfish was two-fold greater on sheltered sites compared with exposed sites. Reef habitat type strongly governed these interactions with reef slope/base (25%) and shallow sand-patch habitats (38%) hosting a majority of aggregative damselfish-branching coral associations compared to reef flat (10%), crest (16%), and wall habitats (11%). Among the focal coral species, Seriatopora hystrix hosted the highest damselfish biomass (12.45 g per occupied colony) and Acropora intermedia the least (6.87 g per occupied colony). Analyses of local coral colony traits indicated that multiple factors governed colony usage, including spacing between colonies on the benthos, colony position, and colony branching patterns. Nevertheless, the morphological and habitat characteristics that determine whether or not a colony is occupied by fish varied among coral species. These findings illuminate the realized niche of one of the most important and abundant reef fish families and provide a context for understanding how fish–coral interactions influence coral population and community level processes.

Proliferation of macro alga <i>Chaetomorpha linum</i> in shallow coral reef areas of Shingle Island, Gulf of Mannar, Southeastern India

In May 2015, during summer, macro alga Chaetomorpha linum was seen entangled in high density on coral colonies at northern part of the Shingle Island (09°14’607”N 078°13’863”E) in Gulf of Mannar, Southeastern India. Underwater assessment revealed that C. linum bloom has proliferated on coral colonies of Acropora and non-acropora species. Filaments of C. linum formed larger mats and got entangled with coral colonies reducing light making hypoxia. The inter tidal zone of northern part of the Shingle Island has rich coral cover with about 23.5% at 0.5 to 3.0 meter depth (Patterson et al., 2007). Live coral cover decreased from 23.5% to 18.5% due to the sudden proliferation of C. linum. Maximum coral mortality was observed in branching corals such as Montipora divaricata, Acropora cytherea and Pocillopora damicornis. Other coral species under stress were Acropora intermedia, A. muricata, Montipora foliosa, Echinopora lamellosa, Porites solida and Favia pallida (Fig. 1 A to D).The present observation can be useful for further investigations regarding the spreading rate, algal biomass, nutrient level, and status of associated biodiversity from the bloom affected reef area.

Community-based, low-tech method of restoring a lost thicket of Acropora corals

Abstract Due to unregulated blast fishing and episodic bleaching events, the back-reef zone near Barangay Lucero in Bolinao, Pangasinan, Philippines, was reduced to a barren area of unconsolidated sand and coral rubble. Anecdotal accounts from local inhabitants, scientific reports, and examination of rubble on the substratum revealed that the area had been dominated by staghorn Acropora corals prior to degradation. With no significant signs of natural recovery, a low-tech restoration method that is both transferable to the community and cost-effective was devised and implemented. Through the help of local inhabitants, 450 fragments of two staghorn coral species (Acropora intermedia and A. pulchra) were transplanted, without using SCUBA equipment, in a total of six 4 × 4 m plots. There were two transplant density treatments: low and high, receiving 25 and 50 fragments of each coral species, respectively. Survivorship and growth of transplants, as well as the assemblage of fishes and macroinvertebrates inside the transplantation and control plots, were monitored periodically for up to 19 months. Transplant survivorship was generally high (68–89%) at the end of the study. There was also an average of a 15-fold increase in ecological volume of the transplants (from 1784.25 ± 162.75 to 26 540.765 ± 4547.25 cm3). Consequently, a significantly higher number of fish and of macroinvertebrates was recorded inside the transplantation plots than in the control plots, indicating signs of restoration success with the reintroduction of the two coral species. Exhibiting significant differences in coral cover, fish biomass and abundance, high-density is more cost-effective than low-density treatment, attaining optimal effects on key reef recovery parameters. The total cost of restoring a thicket of Acropora in a sandy-rubble field using this low-tech rehabilitation method with community participation was estimated to be US$9198.40 ha−1 (US$0.90 m−2), and thus ∼60% cheaper than without community involvement. Community involvement not only reduced the cost of the restoration activity but also provided the community with a sense of ownership and responsibility for their resources, thus ensuring the long-term success of the intervention.

Pole-ward range expansion of Acropora spp. along the east coast of Australia

[Extract] Global temperature has warmed approximately 0.35 °C over the last 50 years. In response, many tropical species are expanding their ranges pole-ward. For example, a number of tropical fish species have recently established populations in temperate regions along the east coast of Australia, as rises in sea temperatures enable them to survive over winter (Figueria and Booth 2010). Similarly, in Japan, two common tropical Acropora species have been expanding their range pole-ward since the 1930s (Yamano et al. 2011). However, there is no evidence to date of similar changes in the distribution of corals along the east coast of Australia. In December 2011, in the Solitary Islands (30 °S), we observed four coral species that had not been recorded in the previous extensive surveys of scleractinian corals (Harriott et al. 1994 and references therein): Acropora intermedia, A. microclados, A. monticulosa (Fig. 1) and A. gemmifera. These species are well defined morphologically, they are easy to recognise in the field and the colonies observed were all large (Fig. 1). Consequently, they were unlikely to have been overlooked in the previous surveys. Average winter temperatures in the Solitary Islands have increased by approximately 0.5 °C since 1975 (Figueria and Booth 2010), the date of the first coral surveys. These pole-ward range expansions raise the possibility that corals along the east coast of Australia may be in the process of adjusting to changes in the regional environment caused by global warming.

Food availability promotes rapid recovery from thermal stress in a scleractinian coral

Bleaching in corals due to environmental stress represents a loss of energy intake often leading to an increase in mortality risk. Successful coral recovery from severe bleaching events may depend on the rate of replenishment of algal symbiont populations following the period of thermal stress, the supply of an alternative food source, or both. Here, we explore the role of food availability in promoting the survival and recovery of a common coral (Acropora intermedia) following acute experimentally induced thermal stress. Fed corals were provided with live rotifers daily, to maintain densities of zooplankton in tanks that are typical of coral reefs. After a 6-week acclimation phase, heated corals were subjected to a +4 °C thermal anomaly for a 7-day period (bleaching phase) then temperatures were returned to normal for a further 2 weeks (recovery phase). Results demonstrated that heated corals had higher survival when they were provided with heterotrophic food. Fed corals experienced reduced loss of chlorophyll a, relative to unfed corals. During the recovery phase, both fed and unfed corals recovered within a few days; however, fed corals recovered to pre-bleaching phase levels of chlorophyll a, whereas unfed corals stabilized approximately one-third below this level. Protein levels of fed corals declined markedly during the bleaching phase, but recovered all of their losses by the end of the recovery phase. In contrast, unfed corals had low protein levels that were maintained throughout the experiment. To the extent that these results are representative of corals’ responses to thermal anomalies in nature, the findings imply that availability of particulate food matter has the potential to increase corals’ capacity to survive thermally induced bleaching and to ameliorate its sub-lethal effects. They also support the hypothesis that different rates of heterotrophy are an important determinant of variation in resilience to thermal stress among reef environments.

Holocene key coral species in the Northwest Pacific: indicators of reef formation and reef ecosystem responses to global climate change and anthropogenic stresses in the near future

The geological record of key coral species that contribute to reef formation and maintenance of reef ecosystems is important for understanding the ecosystem response to global-scale climate change and anthropogenic stresses in the near future. Future responses can be predicted from accumulated data on Holocene reef species identified in drillcore and from data on raised reef terraces. The present study analyzes a dataset based on 27 drillcores, raised reef terraces, and 134 radiocarbon and U–Th ages from reefs of the Northwest Pacific, with the aim of examining the role of key coral species in reef growth and maintenance for reef ecosystem during Holocene sea-level change. The results indicate a latitudinal change in key coral species: arborescent Acropora (Acropora intermedia and Acropora muricata) was the dominant reef builder at reef crests in the tropics, whereas Porites (Porites australiensis, Porites lutea, and Porites lobata) was the dominant contributor to reef growth in the subtropics between 10,000 and 7000 cal. years BP (when the rate of sea-level rise was 10 m/ka). Acropora digitifera, Acropora hyacinthus, Acropora robusta/A. abrotanoides, Isopora palifera, Favia stelligera, and Goniastrea retiformis from the corymbose and tabular Acropora facies were the main key coral species at reef crests between 7000 and 5000 cal. years BP (when the rate of sea-level rise was 5 m/ka) and during the following period of stable sea-level. Massive Porites (P. australiensis, P. lutea, and P. lobata) contributed to reef growth in shallow lagoons during the period of stable sea level. Key coral species from the corymbose and tabular Acropora facies have the potential to build reefs and maintain ecosystems in the near future under a global sea-level rise of 2–6 m/ka, as do key coral species from the arborescent Acropora facies and massive Porites facies, which show vigorous growth and are tolerant to relatively deep-water, low-energy environments. However, these species are likely to experience severe mortality in upcoming decades due to natural and anthropogenic stresses. Consequently, this damage will lead to a collapse in reef formation and the maintenance of reef ecosystems in the near future. This study emphasizes the need for research into the conservation of key coral species.

High CO2 enhances the competitive strength of seaweeds over corals.

Space competition between corals and seaweeds is an important ecological process underlying coral-reef dynamics. Processes promoting seaweed growth and survival, such as herbivore overfishing and eutrophication, can lead to local reef degradation. Here, we present the case that increasing concentrations of atmospheric CO2 may be an additional process driving a shift from corals to seaweeds on reefs. Coral (Acropora intermedia) mortality in contact with a common coral-reef seaweed (Lobophora papenfussii) increased two- to threefold between background CO2 (400 ppm) and highest level projected for late 21st century (1140 ppm). The strong interaction between CO2 and seaweeds on coral mortality was most likely attributable to a chemical competitive mechanism, as control corals with algal mimics showed no mortality. Our results suggest that coral (Acropora) reefs may become increasingly susceptible to seaweed proliferation under ocean acidification, and processes regulating algal abundance (e.g. herbivory) will play an increasingly important role in maintaining coral abundance.

A comparative study of methods for surface area and three‐dimensional shape measurement of coral skeletons

The three‐dimensional morphology and surface area of organisms such as reef‐building corals is central to their biology. Consequently, being able to detect and measure this aspect of corals is critical to understanding their interactions with the surrounding environment. This study explores six different methods of three‐dimensional shape and surface area measurements using the range of morphology associated with the Scleractinian corals: Goniopora tenuidens, Acropora intermedia, and Porites cylindrica. Wax dipping; foil wrapping; multi‐station convergent photogrammetry that used the naturally occurring optical texture for conjugate point matching; stereo photogrammetry that used projected light to provide optical texture; a handheld laser scanner that employed two cameras and a structured light source; and X‐ray computer tomography (CT) scanning were applied to each coral skeleton to determine the spatial resolution of surface detection as well as the accuracy of surface area estimate of each method. Compared with X‐ray CT, wax dipping provided the best estimate of the surface area of coral skeletons that had external corallites, regardless of morphological complexity. Foil wrapping consistently showed a large degree of error on all coral morphologies. The photogrammetry and laserscanning solutions were effective only on corals with simple morphologies. The two techniques that used projected lighting were both subject to skeletal light scattering, caused by both gross morphology and meso‐coral architecture and which degraded signal triangulation, but otherwise provided solutions with good spatial resolution. X‐ray CT scanning provided the highest resolution surface area estimates, detecting surface features smaller than 1000 µm2.

Energetics approach to predicting mortality risk from environmental stress: a case study of coral bleaching

1. Coral bleaching events, predicted to increase in frequency and severity as a result of climate change, are a threat to tropical coral-reef ecosystems worldwide. Although the onset of spatially extensive, or 'mass', bleaching events can be predicted using simple temperature stress metrics, no models are available for predicting coral mortality risk or sub-lethal stress associated with bleaching. Here, we develop a model that links the functional response of colony energy balance and energy store dynamics to coral mortality risk and recovery during and following bleaching events. 2. In a series of simulations using response functions and parameter values derived from experimental studies for two Indo-Pacific coral species (Acropora intermedia and Montipora monasteriata), we demonstrate that prior energy-costly disturbances and alternative energy sources are both important determinants of coral mortality risk during and following bleaching. 3. The timing of the onset of coral mass mortality is determined by a combination of bleaching severity (loss rate of photopigments), duration of the bleaching event, heterotrophy and the size of energy reserves (as lipid stores) before bleaching occurs. 4. Depending on initial energy reserves, model results showed that high rates of heterotrophy could delay the onset of coral mortality by up to three weeks. Survival following bleaching was also strongly influenced by remaining lipid reserves, rates of heterotrophy, and rates of photopigment (or symbiont) recovery. 5. Our results indicate that energy-costly disturbances and low availability of food, before and during bleaching events, respectively, work to increase bleaching-induced coral mortality risk for acroporid corals on Indo-Pacific reefs.

Bleaching, energetics, and coral mortality risk: Effects of temperature, light, and sediment regime

The most severe outcome of coral bleaching is colony mortality. However, the risk of mortality is one of the least understood consequences for reef corals under climate‐change scenarios. Specifically, links among combinations of temperature anomalies, varying solar irradiance, reduced water quality, and mortality risks are unclear. Here, we analyze the effects of high temperature, irradiance, and sediment loading on coral survivorship in a controlled tank experiment using Acropora intermedia from the inner Great Barrier Reef lagoon. Survival analyses based on the fate of 1600 subcolonies revealed that temperature and sediment exerted strong effects on coral mortality risk. As expected, high temperature increased mortality risk at all light and sediment levels. However, high sediment reduced mortality under high temperature and/or high light, potentially by alleviating light pressure and by providing an alternative food source for bleached corals. A survivorship model using coral energy status (lipid stores) as a predictor variable provided an excellent fit to the data, suggesting that much of the variation in survivorship among treatments and over time can be explained by colony energetics. Our study provides a new framework for predicting coral mortality risk under complex bleaching scenarios in which multiple environmental variables are involved.

Copepoda associated with scleractinian corals on the Great Barrier Reef, northeastern Australia, with a key to the genera of the Lichomolgidae

Nine new species and three new genera, Parandrianellus, Scyphuliger, and James-cookina, are associated with various species of hard corals in the vicinity of Lizard Island, Big Broadhurst Reef, and Bowl Reef on the Great Barrier Reef. These copepods include the lichomolgids Parandrianellus annulatus from Hydnophora rigida, Scyphuliger concavipes from Acropora hyacinthus and Acropora sarmentosa, Scyphuliger manifestus from Acropora hyacinthus and Acropora squarrosa, James-cookina redacta from Echinopora horrida, Panjakus eumeces from Hydnophora rigida, Anchimolgus abbreviatus and Anchimolgus tanaus from Acrhelia horrescens, Anchimolgus exsertus from Echinopora horrida, and Odontomolgus bulbalis from Merulina ampliata. Schedomolgus tenuatus Humes, 1990, recorded from Acropora hyacinthus and Acropora humilis, is transferred to the genus Scyphuliger. Schedomolgus lobophorus (Humes and Ho, 1968) is recorded from Acropora hyacinthus, Acropora humilis, Acropora sarmentosa, and Acropora intermedia; Amarda goniast...