Acanthaster planci infestations of reefs and coral assemblages in Japan: a retrospective analysis of control efforts

Reef-building corals have been extensively degraded by Acanthaster planci infestations which have continued to spread throughout the Ryukyu archipelago since 1969. Intensive control efforts were undertaken by fishermen and divers by hand-collecting and disposal on land with removal of about 13 million starfish at the total cost of over 600 million yen from 1970 to 1983 fiscal year. The control programs were mostly unsuccessful for saving the reefs from predation because the efforts were executed on the basis of collecting efficiency, so that significant numbers of starfish continued predation after each belated campaign. Certain coral assemblages outside the Ryukyus were infested with unusually large numbers of A. planci simultaneously with the northern part of Okinawa Island and its neighboring islands in the early seventies. A shift of infestation sites occurred in the extratropical waters in the mid-seventies when the warm current, Kuroshio, changed its path and left the coast of Honshu, the main island of Japan. The Kuroshio is considered to be transporting larval A. planci downstream from the Ryukyus where large aggregations have continued to exist at different areas all through the period.     

Genomic organization of Hox and ParaHox clusters in the echinoderm,Acanthaster planci

The organization of echinoderm Hox clusters is of interest due to the role that Hox genes play in deuterostome development and body plan organization, and the unique gene order of the Hox complex in the sea urchin Strongylocentrotus purpuratus, which has been linked to the unique development of the axial region. Here, it has been reported that the Hox and ParaHox clusters of Acanthaster planci, a corallivorous starfish found in the Pacific and Indian oceans, generally resembles the chordate and hemichordate clusters. The A. planci Hox cluster shared with sea urchins the loss of one of the medial Hox genes, even‐skipped (Evx) at the anterior of the cluster, as well as organization of the posterior Hox genes. genesis 52:952–958, 2014. © 2014 Wiley Periodicals, Inc.     

Soft coral abundance on the central Great Barrier Reef: effects of Acanthaster planci, space availability, and aspects of the physical environment

 The distribution and abundance of soft coral genera on reefs of the central Great Barrier Reef was investigated in relation to reef position, recent history of disturbance, wave exposure, substratum slope and depth. Eighty-five 25 m long transects were surveyed at 10 m depth on windward sides of 14 mid- and outer-shelf reefs. A further 75 transects in different zones on one mid-shelf reef (Davies Reef) between 5 and 30 m depth were investigated. The crown-of-thorns starfish Acanthaster planci had caused large-scale mortality of scleractinians on eight of these reefs five to ten years prior to the study, and as a result, scleractinian cover was only 35–55% of that on the six unimpacted reefs. On the impacted reefs, stony corals with massive and encrusting growths form had smaller average colony diameters but similar or slightly lower numerical abundance. In contrast, mean colony size, cover and abundance of branching stony corals showed no difference between impacted and unimpacted reefs. Twenty-four genera of soft corals (in eight families) were recorded, and none showed different abundance or cover in areas of former A. planci impact, compared to unaffected sites. Similarly, no difference was detected among locations in the numbers or area cover of sponges, tunicates, zoanthids, Halimeda or other macro-algae. Mean soft coral cover was 2 to 5% at 10 m on sheltered mid-shelf reefs, and 12 to 17% on more current-exposed reefs. Highest cover and abundances generally occurred on platforms of outer-shelf reefs exposed to relatively strong currents but low wave energy. On Davies Reef, cover and colony numbers of the families Nephtheidae and Xeniidae were low within the zone of wave impact, in flow-protected bays and lagoons, on shaded steep slopes, and at depths above 10 and below 25 m. In contrast, distributions of genera of the family Alcyoniidae were not related to these physical parameters. The physical conditions of a large proportion of habitats appear “sub-optimal” for the fastest growing taxa, possibly preventing an invasion of the cleared space. Thus, in the absence of additional stress these shallow-water fore-reef zones appear sufficiently resilient to return to their pre-outbreak state of scleractinian dominance. Accepted: 20 August 1996     

Identification of 23-demethylacanthasterol in an asteroid,Acanthaster planci and its synthesis

23-Demethylacanthasterol was identified in an asteroid, $\text{Acanthaster planci}$, by GC-MS analysis and direct comparison with the synthetic sample prepared from 23-demethylgorgo-sterol. The sterol composition of $\text{A. planci}$ is also described.     

Individual recognition and phenotypic variability in Acanthaster planci (Echinodermata: Asteroidea)

Summary A coding method for identifying individuals by utilizing natural attributes (numbers and disposition of arms, madrporites, anuses, spines and deformities) permits individual recognition of crown-of-thorns sea stars Acanthaster planci. Because natural injuries altering parts of the code are frequent in A. planci (present in 20% to 40% of the individuals in a population), the physiognomy of the centrally located periproct, which is much less frequently injured than peripherally located areas, was used in combination with the arrangement of arms and madreporites. Identical madreporite/arm codes occurred in fewer sea stars in Guam (0%) than in Panamá (14%). The greater variability among sea stars at the western Pacific locality could be due in part to the higher incidence of gross deformities (presumed injuries) in Guam (43%) compared with Panamá (17%).     

Larvae of the coral eating crown‐of‐thorns starfish,Acanthaster planci in a warmer‐high CO2 ocean

Outbreaks of crown‐of‐thorns starfish (COTS), Acanthaster planci, contribute to major declines of coral reef ecosystems throughout the Indo‐Pacific. As the oceans warm and decrease in pH due to increased anthropogenic CO₂ production_, coral reefs are also susceptible to bleaching, disease and reduced calcification. The impacts of ocean acidification and warming may be exacerbated by COTS predation, but it is not known how this major predator will fare in a changing ocean. Because larval success is a key driver of population outbreaks, we investigated the sensitivities of larval A. planci to increased temperature (2–4 °C above ambient) and acidification (0.3–0.5 pH units below ambient) in flow‐through cross‐factorial experiments (3 temperature × 3 pH/pCO₂ levels). There was no effect of increased temperature or acidification on fertilization or very early development. Larvae reared in the optimal temperature (28 °C) were the largest across all pH treatments. Development to advanced larva was negatively affected by the high temperature treatment (30 °C) and by both experimental pH levels (pH 7.6, 7.8). Thus, planktonic life stages of A. planci may be negatively impacted by near‐future global change. Increased temperature and reduced pH had an additive negative effect on reducing larval size. The 30 °C treatment exceeded larval tolerance regardless of pH. As 30 °C sea surface temperatures may become the norm in low latitude tropical regions, poleward migration of A. planci may be expected as they follow optimal isotherms. In the absence of acclimation or adaptation, declines in low latitude populations may occur. Poleward migration will be facilitated by strong western boundary currents, with possible negative flow‐on effects on high latitude coral reefs. The contrasting responses of the larvae of A. planci and those of its coral prey to ocean acidification and warming are considered in context with potential future change in tropical reef ecosystems.     

Morphology of spines and spine joint in the crown-of-thorns starfish Acanthaster planci (Echinodermata,Asteroida)

Summary Morphology and movement of the spines of Acanthaster planci were studied. All surfaces of the animal are covered with spines. The spines on the aboral surface are cylindrical with sharp tips. The spines on the oral surface are flat; they bend over to cover the mouth and the ambulacral grooves when these soft parts are stimulated. Those on the side of the animal make a barrier of crossed spines. Thus the structure and movement of the spines are well-adapted for defense.The junction between the primary aboral spine and its pedicel makes a movable joint. The ultrastructure of the connective tissue at the joint was studied. The connective tissue is mainly composed of collagen fibers. Presumed neurosecretory cells with processes which are filled with electron-dense granules of 0.2 m diameter were found between collagen fibers. Muscle fibers are mainly found in the connective tissue at the central holes. These observations support the view that the joint connective tissue has catch properties.     

Red Sea coral reef trajectories over 2 decades suggest increasing community homogenization and decline in coral size

Three independent line intercept transect surveys on northern Red Sea reef slopes conducted in 1988/9 and 1997/8 in Egypt and from 2006-9 in Saudi Arabia were used to compare community patterns and coral size. Coral communities showed scale-dependent variability, highest at fine spatial and taxonomic scale (species-specific within and among reef patterns). At coarser scale (generic pattern across regions), patterns were more uniform (regionally consistent generic dominance on differently exposed reef slopes and at different depths). Neither fine- nor coarse-scale patterns aligned along the sampled 1700 km latitudinal gradient. Thus, a latitudinal gradient that had been described earlier from comparable datasets, separating the Red Sea into three faunistic zones, was no longer apparent. This may indicate subtle changes in species distributions. Coral size, measured as corrected average intercept of corals in transects, had decreased from 1997 to 2009, after having remained constant from 1988 to 1997. Recruitment had remained stable (～12 juvenile corals per m(2)). Size distributions had not changed significantly but large corals had declined over 20 years. Thus, data from a wide range of sites taken over two decades support claims by others that climate change is indeed beginning to show clear effects on Red Sea reefs.     

History and dynamics of the crown-of-thorns starfish Acanthaster planci (L.) in the Suva area,Fiji

Annual recruitment of Acanthaster planci over a 13 year period in a known juvenile refuge substratum on Suva Reef was very patchy in time and space. Macroscale recruitment events resulted in outbreaks over many thousands of hectares over 100 km of coastline whereas localised but intensive mesoscale events resulted in concenrated aggregations over areas of several tens of hectares. A very low level of recruitment occurred in most years but three intensive, macroscale recruitment events occurred in 1977, 1984 and 1987, and two localised but intensive recruitment events occurred in 1982 and 1983. Annual recruitment of A. planci between 1975–89 had no overt relationship with rainfall events, as proposed in the terrestrial run-off hypothesis on the cause of primary out-breaks. Growth rates within monitored cohorts were highly variable, but mean growth rates of two cohorts 1984 and 1987 were relatively similar. Mortality rates of three monitored cohorts were variable. Longevity of the 1977 cohort was 7–8 years, while that of the 1984 cohort was 2–3 years. Mortality of the 1987 cohort has been low to date (i.e. 4 years of age). Disease, attributed to an undescribed sporozoan pathogen, was responsible for two mass mortalities in the 1984 cohort, in 1984 and in 1986, and eventually resulted in the extinction of this cohort. Anecdotal reports indicate that outbreaks of A. planci are increasing in frequency and severity. According to Fijian reef fishermen, the starfish were low to moderate in abundance in the Suva area from the 1920s to the 1960s. A progressive build up occurred on some reefs in 1963–67 leading to a major outbreak episode from 1967–1971. The outbreaks were in a chronic phase between 1977–1989. Our findings demonstrate that there is no invariable pattern or process involved in the population dynamics of A. planci and that a single explanation of the A. planci phenomenon is therefore unlikely.     

Sightability as an indicator of bias in manta tow surveys of Acanthaster planci: comment on Fernandes,Marsh, Moran and Sinclair

The manta tow technique has been extensively used in broadscale surveys of A. planci on the Great Barrier Reef (Kenchington 1984; Moran et al. 1990). Frequently the unit of interest is an entire reef, or large part thereof, although Kenchington and Morton (1976) indicated that manta tow counts could be calibrated to give accurate estimates of scuba counts over smaller reef areas. This was experimentally tested by Fernandes et al. (1990) using the concept of sightability and they conclude that The manta tow technique obviously cannot provide accurate estimates of the absolute number of starfish. The aims of this note are: (i) to indicate logical flaws in Fernandes et al. (1990) which invalidate the above conclusion; (ii) to provide a survey data set with similar characteristics to the data of Fernandes et al. (1990) which demonstrates that manta tow counts can provide accurate estimates of scuba counts; (iii) to suggest a more appropriate perspective than sightability to address questions of bias, precision and accuracy of survey data.     

The thermal tolerance of crown-of-thorns (Acanthaster planci) embryos and bipinnaria larvae: implications for spatial and temporal variation in adult populations

To understand the role of sea temperature on the population biology of the crown-of-thorns sea star Acanthaster planci, the thermal window for embryonic and larval development was investigated. In two experiments, the response of embryos and larvae across 12 temperatures from 19.4 to 36.5 °C was quantified as the percentage of individuals reaching cleavage stage embryos, blastula, gastrula, early-bipinnaria, late-bipinnaria larvae or abnormal. Measurements were made at 7 times up to 72 h post-fertilisation, with the morphometrics of larvae measured in the 72-h sample. Acanthaster planci developed at temperatures between 19.4 and 33.2 °C, with a thermal window for development to the late-bipinnaria stage between 25.6 and 31.6 °C. Development rate, normal development and larval size were optimal at 28.7 °C, with development rates remaining relatively constant up to 31.6 °C. Rates of abnormality increased steadily (early embryonic stages) above 28.7 °C and was 100 % at temperatures approaching 33 °C. These experiments provide a more detailed insight into the response of A. planci developmental stages to temperature. The present day distribution of the species in eastern Australia overlap with the optimal thermal window for development to the late-bipinnaria stage (≈25–32 °C), implying a role of temperature in controlling population distributions and abundances. Despite this, short- or long-term temperature increases may not be a major modulator of the crown-of-thorns recruitment success, population dynamics and distribution in the future as no significant change in development rates, larval survival and growth occurred within this thermal window. Therefore, moderate (1–2 °C) increases in sea temperatures caused by El Niño or near-future ocean warming may not drive an increase in developmental and settlement success. Indeed, without any acclimation to warmer temperatures expected under near-future warming (+2 to 4 °C), climate change could ultimately reduce larval survival due to elevated mortality above the optimal development temperature.     

Body size, rarity, and phylogenetic community structure: insights from diving beetle assemblages of Alberta

Although it is implicit that interactions between species depend on their traits, studies on the probability of finding related species in a community are in their infancy. Community composition and species richness of predaceous diving beetles (Dytiscidae: Coleoptera) have been used as indicators of freshwater ecosystem function yet no incorporation of phylogenetic relationships of coexisting dytiscids has been attempted to date. Improved knowledge of phylogenetic relationships and phylogenetic community structure analysis methods may provide additional insight into the relationships between community composition and species richness, thus impacting our interpretation of aquatic indicator species metrics. Here, we use museum records of dytiscid beetles in 53 lakes of Alberta, Canada to: (1) compile a supertree of dytiscid beetles that live in the province, (2) examine whether coexisting dytiscids tend to be more or less related than expected by chance, and (3) examine whether phylogenetic structuring depends on species richness or mean size of coexisting species. We find that, although the majority of dytiscid assemblages exhibited phylogenetic clustering, the extent to which this occurred depended on the mean size of dytiscids. We discuss the potential mechanisms and implications of the observed patterns in phylogenetic clustering, along with data that would further improve our understanding of community dynamics in dytiscid beetles.     

Recent changes in coral assemblages of a South African coral reef, with recommendations for long-term monitoring

Two-mile reef, Sodwana, South Africa is an unusual coral reef, being situated on a submerged fossilized sand dune and being very southerly (27°54). It is a popular Scuba diving venue receiving about 100000 dives year^–1. The line-intercept transect method, as recommended by the global coral reef monitoring network (GCRMN), was used to determine soft coral, hard coral and other benthos percentage cover. Physical coral damage, disease and bleaching were also recorded. Results were compared with those of B. Riegl (1993 – unpublished PhD thesis) 5 to 7 years earlier. The reef appears to be ecologically and highly dynamic. In the interim, there has been an increase in living benthos cover of 22.3% but also an increase in coral bleaching from 0% in 1993 to 1% in 1998. Physical damage, despite the large number of dives on the reef was minimal (1.52%), although it appears as if coral diseases may be increasing. The 20-m transects recommended by GCRMN are too long for this highly rugose reef with its distinct ridges and gullies. It is recommended that benthos cover, coral damage, bleaching and disease should be monitored annually using 40 5-m transects on the reef ridges and 40 5-m transects on the reef slopes.     

Interactions between coral restoration and fish assemblages: implications for reef management

Corals create complex reef structures that provide both habitat and food for many fish species. Because of numerous natural and anthropogenic threats, many coral reefs are currently being degraded, endangering the fish assemblages they support. Coral reef restoration, an active ecological management tool, may help reverse some of the current trends in reef degradation through the transplantation of stony corals. Although restoration techniques have been extensively reviewed in relation to coral survival, our understanding of the effects of adding live coral cover and complexity on fishes is in its infancy with a lack of scientifically validated research. This study reviews the limited data on reef restoration and fish assemblages, and complements this with the more extensive understanding of complex interactions between natural reefs and fishes and how this might inform restoration efforts. It also discusses which key fish species or functional groups may promote, facilitate or inhibit restoration efforts and, in turn, how restoration efforts can be optimised to enhance coral fish assemblages. By highlighting critical knowledge gaps in relation to fishes and restoration interactions, the study aims to stimulate research into the role of reef fishes in restoration projects. A greater understanding of the functional roles of reef fishes would also help inform whether restoration projects can return fish assemblages to their natural compositions or whether alternative species compositions develop, and over what timeframe. Although alleviation of local and global reef stressors remains a priority, reef restoration is an important tool; an increased understanding of the interactions between replanted corals and the fishes they support is critical for ensuring its success for people and nature.     

Interspecific variation in the defensive responses of obligate plant-ants: experimental tests and consequences for herbivory

The aggressive behavior of ants that protect plants from herbivores in exchange for rewards such as shelter or food is thought to be an important form of biotic defense against herbivory, particularly in tropical systems. To date, however, no one has compared the defensive responses of different ant taxa associated with the same plant species, and attempted to relate these differences to longer-term efficacy of ant defense. We used experimental cues associated with herbivory—physical damage and extracts of chemical volatiles from leaf tissue—to compare the aggressive responses of two ant species obligately associated with the Amazonian myrmecophyte Tococa bullifera (Melastomataceae). We also conducted a colony removal experiment to quantify the level of resistance from herbivores provided to plants by each ant species. Our experiments demonstrate that some cues eliciting a strong response from one ant species elicited no response by the other. For cues that do elicit responses, the magnitude of these responses can vary interspecifically. These patterns were consistent with the level of resistance provided from herbivores to plants. The colony removal experiment showed that both ant species defend plants from herbivores: however, herbivory was higher on plants colonized by the less aggressive ant species. Our results add to the growing body of literature indicating defensive ant responses are stimulated by cues associated with herbivory. However, they also suggest the local and regional variation in the composition of potential partner taxa could influence the ecology and evolution of defensive mutualisms in ways that have previously remained unexplored.     

Clinical,pathophysiological and structure/function consequences of modification of albumin by Amadori-glucose adducts

Background

The nonenzymatic condensation of glucose with albumin results in the formation of albumin modified by Amadori glucose adducts, the principal form in which glycated albumin exists in vivo.

Scope of review

This review focuses on (a) the utility of measurement of Amadori-modified glycated albumin (AGA) as a biomarker in diabetes, where elevated levels attend the hyperglycemic state; (b) the role of AGA as a causal factor in the pathogenesis of complications of diabetes; (c) effects on transport properties; and (d) structural and functional consequences of the modification of albumin by Amadori glucose adducts. It does not discuss counterparts with respect to Advanced Glycation Endproducts (AGE), which may be found in other publications.

Major Conclusions

Nonenzymatic glycation of albumin, which is increased in diabetes, has clinical relevance and pathophysiologic importance, with ramifications for the management of this disease, the development of its complications, and the transport of endogenous and exogenous ligands.

General significance

Appreciation of the manifold consequences of AGA has afforded new avenues for assessing clinical management of diabetes, awareness of the impact of nonenzymatic glycation on albumin biology, insights into the pathogenesis of vascular complications of diabetes, and avenues of investigation of and intervention strategies for these complications. This article is part of a Special Issue on albumin. This article is part of a Special Issue entitled Serum Albumin.