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  • 1
    Electronic Resource
    Electronic Resource
    Larval Development and Metamorphosis of Acanthaster planci (Asteroidea) (1971)
    [s.l.] : Nature Publishing Group
    Nature 232 (1971), S. 655-657 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] In this study A. planci was reared in the laboratory from fertilization to juvenile starfish and a preliminary study has been made of the influence of temperature, salinity, food and substrate on survival and development. Previously, Hender-son5 and Mortensen6 reared A. planci to late bipinnaria ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/232655a0
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  • 2
    Electronic Resource
    Electronic Resource
    Hybrid crown-of-thorns starfish (Acanthaster planci x A. brevispinus) reared to maturity in the laboratory (1976)
    [s.l.] : Nature Publishing Group
    Nature 263 (1976), S. 409-412 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Ripe specimens of A. brevispinus were collected by trawling in December 1973, near the time of annual gamete release by A. planci in Great Barrier Reef waters6. Gonads were dissected from starfish of both taxa. Ovaries were treated with 10?5 M 1-methyladenine in sea water to mature the oocytes7, ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/263409a0
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  • 3
    Electronic Resource
    Electronic Resource
    Genetic differences between geographic populations of the Crown-of-thorns starfish throughout the Pacific region (1988)
    Springer
    Marine biology 98 (1988), S. 359-368 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ten population samples of the Crown-of-thorns starfish Acanthaster planci were collected between March 1982 and August 1983 from localities across the Pacific and were examined for variation at 14 enzyme loci using starch-gel electrophoresis. A sample of A. brevispinus was also examined for comparison. In contrast to the considerable genetic differentiation between A. brevispinus and A. planci populations (D=0.20±0.02), the genetic differences between geographic populations of A. planci were small (D=0.03±0.00; F ST =0.07±0.02), in spite of the great distances separating them. A positive correlation was observed between degree of genetic differentiation and geographic scale, suggesting that the genetic homogeneity among A. planci populations is due to gene flow by planktonic larval dispersion. In view of such macrogeographic homogeneity, it is striking that significant allele frequency differences were observed between adjacent populations separated by approximately only 10 km. The Hawaiian population was most differentiated from other populations. Treating the morphologically-distinctive, eastern Pacific Acanthaster as a separate species, A. ellisii, is not supported by these data. The lack of unique alleles in these two central and eastern Pacific populations suggests that they were derived from those in the western Pacific.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00391112
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of various temperature cycles on the larval development of the gastropod molluscCrepidula fornicata (1979)
    Springer
    Marine biology 51 (1979), S. 111-117 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Veligers ofCrepidula fornicata (L.) were reared for 12 days at constant temperatures of 15°, 20°, 25°, 30° and 35°C, and at 5 C° daily cycles of equal periodicity (COEP) over the temperature ranges 15° to 20°C, 20° to 25°C, 25° to 30°C and 30° to 35°C. COEP consisted of equal periods (6 h) of maximum temperature, minimum temperature, and uniformly increasing and decreasing temperature each 24 h period. Survival was high and not influenced by cyclic or constant temperature from 15° to 30°C. At 35°C and COEP 30° to 35°C, all larvae died before Day 6. Shell growth rate increased markedly over the range 15° to 25°C, and growth rates at cyclic temperatures in this range were intermediate between growth rates at the corresponding constant temperatures. Larvae reared at COEP 15° to 20°C and COEP 30° to 35°C had discontinuities in their shells due to inhibition of shell secretion during the adverse part of each temperature cycle. Groups ofc. fornicata veligers were exposed for 2 days to daily temperature cycles of equal and unequal periodicity in the critical 30° to 35°C range. [Cycles of unequal periodicity (COUP) consisted of unequal periods (varying between 3 and 15 h) of maximum and minimum temperature and uniformly increasing and decreasing temperature each 24 h period.] These veligers showed shell growth although their body tissue declined, as indicated by decreasing carbon content per larva. Least shell growth and most body tissue loss occurred in those cycles with the longest exposure to higher temperature. Larvae exposed for arious days to the mildest 30° to 35°C COUP (15 h at 30°C, 3 h increasing temperature, 3 h at 35°C and 3 h decreasing temperature) recovered and resumed normal growth when transferred to constant 30°C, but their growth was retarded in proportion to the number of days in the temperature cycle. Rates of shell growth of veligers in temperature cycles show an immediate effect of environmental temperature, while changes in carbon content per larva better reflect the effects of temperature on general metabolism and survival.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00555190
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  • 5
    Electronic Resource
    Electronic Resource
    Selective feeding by larvae of the crown-of-thorns starfish, Acanthaster planci (L.) (1997)
    Springer
    Coral reefs 16 (1997), S. 47-50 
    Details
    ISSN: 1432-0975
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract.  The effect of phytoplankton size on feeding rates of planktonic larvae of the crown-of-thorns starfish Acanthaster planci (L.) was evaluated by examining their gut contents under an epifluorescence microscope. Concentrations of coccoid cyanobacteria in natural seawater ranged between 1.73 and 5.33×105 cells ml-1 and were three to four orders of magnitude greater than that of eukaryotes. Under these conditions, A. planci larvae ingested similar or smaller numbers of cyanobacteria than eukaryotes. Consequently, clearance rates of A. planci larvae on cyanobacteria were approximately three orders of magnitude lower than those on eukaryotes. Cyanobacteria and eukaryotes in the gut of A. planci larvae had mean equivalent spherical diameters (ESD) of 1–2 μm and 3.6–4.6 μm, respectively. Thus, the volume of cyanobacteria ingested was less than 10% of the volume of eukaryotes ingested. Acanthaster planci larvae were fed cultured phytoplankton Dunaliella tertiolecta and suspensions of three different sizes of plastic beads with fluorescence labelling. There was no significant difference in clearance rates on 6 and 20 μm plastic beads. Clearance rates on 1 μm plastic beads were, however, much lower than those on 6 and 20 μm plastic beads. Clearance rates of A. planci larvae on D. tertiolecta (ca. 5 μm ESD) were significantly higher than those on 6 and 20 μm plastic beads. Apart from particle size, this result shows that feeding of A. planci larvae is influenced by other properties of potential food particles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003380050058
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  • 6
    Electronic Resource
    Electronic Resource
    Population genetic studies of the crown-of-thorns starfish, Acanthaster planci (L.), in the Great Barrier Reef region (1988)
    Springer
    Coral reefs 7 (1988), S. 11-18 
    Details
    ISSN: 1432-0975
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Seven populations of the crown-of-thorns starfish, Acanthaster planci, were compared genetically using starch gel electrophoresis in order to investigate the extent of genetic exchange throughout the Great Barrier Reef (GBR) region. These populations extended from Lizard Island in the north to One Tree Island in the south, a distance of approximately 1300 km. Thirteen of 36 enzymes assayed were genetically interpretable, and 10 (77%) of these were polymorphic. Mean heterozygosity over all loci was 0.225. An analysis of the gene frequency heterogeneity between the populations using Wright's F ST statistic gave an overall F ST of 0.019. The mean unbiased value of Nei's genetic distance between the populations was 0.009. These values indicate a homogeneous genetic composition throughout the range, and are consistent with the hypothesis that gene flow between these populations is high, and that A. planci throughout the GBR region are members of a single, effectively panmictic population. Within this group, the Green Island population was most distinct genetically because of differences in allele frequencies at the MDH-1 locus. Although there is no rigorous method for determining the selective basis for such differences, it is argued that the differences observed in the Green Island population were the result of selection. The basis for selective differences was possibly food availability since, at the time of sampling, the Green Island A. planci were the remnants of a large, high-density population that caused extensive coral mortality, and suffered severe population decline as food became scarce. These findings are consistent with observations of a relatively ordered sequence of outbreaks from north to south along the GBR, suggesting that all outbreaks but the first are secondary. Control measures, both on the GBR and elsewhere, have been unsuccessful except on a very small scale. Unless a vulnerable part of the A. planci life cycle can be identified, it would seem that the greatest chance for successful control would be to identify and control the causes of the primary population outbreak.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00301976
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  • 7
    Electronic Resource
    Electronic Resource
    Linear growth in spines from Acanthaster planci (L.) involving growth lines and periodic pigment bands (1990)
    Springer
    Coral reefs 9 (1990), S. 149-154 
    Details
    ISSN: 1432-0975
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract We report the first observations of a linear growth pattern in aboral spine ossicles of adult Acanthaster planci (L.). This is unlike the spine development of other echinoderms. Growth in aboral spine ossicles of A. planci is essentially by addition of stereom at the base and the spine's growth history is preserved along its length. There are numerous growth lines perpendicular to the long axis of the ossicle. These are clearly evident in longitudinal spine sections and apparently caused by frequent growth episodes. There are periodic pigment bands which are parallel to the growth lines and evident on the surface of the ossicle. Basal growth of the spine ossicle and the nature of the growth lines were confirmed by tetracycline staining. Size/frequency analyses of a population of A. planci from Davies Reef (GBR) found spine ossicle growth, but not body diameter growth, over the six month period between sampling dates. The additional pigment banding in spine ossicles of 4 individuals recaptured after 6 months suggests that pigment bands are laid down seasonally. If pigment band cyclicity is validated, it offers a simple method for ageing adults of A. planci in field populations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00258227
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  • 8
    Electronic Resource
    Electronic Resource
    Nitrogen flux in giant clams: size-dependency and relationship to zooxanthellae density and clam biomass in the uptake of dissolved inorganic nitrogen (1993)
    Springer
    Marine biology 117 (1993), S. 381-386 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Tridacnid clams live on coral reefs in the Indo-Pacific, in waters containing low concentrations of inorganic nitrogen. This study examined nitrogen flux in the giant clam Tridacna gigas. Adults and juveniles of this species typically occur with symbiotic dinoflagellates of the genus Symbiodinium sp., often referred to as zooxanthellae, which live in their tissues. Intact clams took up or released dissolved inorganic nitrogen (DIN), with the direction and magnitude of the fluxes dependent on clam size. Non-symbiotic larvae and newly-settled juveniles with few zooxanthellae released ammonium. Larger juveniles and adults depleted ammonium or nitrate from seawater, when offered separately. Rates of uptake of DIN, standardized to either clam wet weight or number of zooxanthellae, were highest in small clams (1 to 5 cm in length), and decreased with increasing clam size (〉5 cm). Clams maintained in seawater containing high concentrations of ammonium (ca. 20 μM) for ≥ 1 wk generally released ammonium in the dark and exhibited net uptake in the light. Freshly isolated zooxanthellae (FIZ) from small clams had higher uptake rates than FIZ from larger clams, implying that the latter may be more nitrogen-sufficient than the former. The gradient of nitrogen sufficiency in giant clams is related to zooxanthellae density, with peaks of both algal density and rates of uptake of DIN occurring in small sizes of clams, whose growth also appears to be limited by nitrogen availability.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00349313
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  • 9
    Electronic Resource
    Electronic Resource
    Nutrient limitation in the giant clam-zooxanthellae symbiosis: effects of nutrient supplements on growth of the symbiotic partners (1993)
    Springer
    Marine biology 117 (1993), S. 655-664 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of ammonium (5, 10 μM N) and phosphate (2, 5, 10 μM P) on the growth of the giant clam Tridacna gigas and its symbiotic dinoflagellate Symbiodinium sp. was examined. A 3 mo exposure to these nutritients significantly increased the N or P composition of the soft tissues, as reflected in a corresponding change in C:N:P ratio. Furthermore, exposure to N or N+P markedly increased the amount of soft tissue, but P alone did not, demonstrating that increased availability of inorganic nitrogen enhances tissue growth of the clam host. With addition of N, or N+P, there was a significant increase in the total number of zooxanthellae per clam, with a corresponding decrease in chlorophyll a (chl a) content per zooxanthella. However, only with N+P was there an increase in the zooxanthellae mitotic index. The inverse relationship between zooxanthellae number and chl a per zooxanthella is consistent with phytoplankton studies indicating conditions of nutrient-limitation. Furthermore, the unaffected C:N:P composition of the zooxanthellae and their relatively low specific-growth rates (4 to 10%) also suggest that they are nutrient-limited in vivo. In particular, their high mean C:N:P ratio of 303:52:1 indicates that, relative to C, they are much more depleted in P and less in N than are free-living phytoplankton. Furthermore, polyphosphates (phosphate reserves) were undetectable, and the activity levels of acid phosphatase in the zooxanthellae were relatively high and not influenced by the host's exposure to increased P concentrations in the sea water, implicating the clam host in active regulation of P availability to its symbiotic algae. This is strong evidence that N-limitation of clam zooxanthellae is a function of the availability of ammonium to the symbiosis while, irrespective of nutrient levels in sea water, clam zooxanthellae still show characteristics of P-limitation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00349778
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  • 10
    Electronic Resource
    Electronic Resource
    Divide or broadcast: Interrelation of asexual and sexual reproduction in a population of the fissiparous hermaphroditic seastar Nepanthia belcheri (Asteroidea: Asterinidae) (1982)
    Springer
    Marine biology 69 (1982), S. 223-233 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Asexual and sexual reproduction were studied in an intertidal population of Nepanthia belcheri (Perrier) at Townsville, Queensland, Australia, by regular sampling over a year (March 1976-March 1977) and by histological analysis of gonads. Fission reached a peak in early winter (April–June), when about 45% of the population showed evidence of recent fission. Propensity for fission was unrelated to longest arm length. Seven-armed seastars predominated in the population and these underwent fission in two stages to produce one 3-armed fragment and two 2-armed fragments. Fission planes were not related to numbers or positions of madreporites. Hermaphroditism was a normal sexual condition in the population. Almost all gonads contained oocytes, but some gonads functioned as ovaries (without spermatogenic tissue) while others functioned as testes. Seastars with mature ovaries were significantly larger than those with mature testes, indicating protandry, as in other hermaphroditic asteroids. However, fission complicates the pattern of gonad development by causing regression or retardation of gonads and by apparently having a masculinizing effect, so that ovaries may change to testes in fission products. There was a period of sexual reproduction in early summer (October–November). This followed the period of intense fission and regeneration, and a population change from predominately functional females to males. Consequently there was an extreme imbalance against mature females at sexual reproduction, further reducing potential fecundity. Thus, sexual reproduction was very subordinate to fission as the means of recruitment. The 450 μm diam eggs probably give rise to pelagic lecithotrophic development and, if this is the case, N. belcheri retains the advantage of complementing reliable recruitment from fission with a dispersive phase. The combination of fission and hermaphroditism is particularly advantageous for a very sparse dispersal of larvae, as a functionally dioecious population may develop from one larva settling in a new locality.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00397488
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