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1.
The euryalinid brittle-star (snake star) Astrobrachion constrictum (Farquhar) lives coiled around the branches of black coral (Antipathes fiordensis) colonies. Twenty-two vertical transects, 10 m wide by 30 m deep, were swum in Doubtful Sound over a 2.5 yr period from 1993
to 1995. Numbers, disc diameters and colour morphotypes of brittle-stars inhabiting coral colonies were recorded. 36.3% of
the coral colonies >200 mm tall (n = 292) hosted ≥1 Astrobrachion constrictum (range 0 to 12). Overall, the population was patchily distributed on the available coral habitat. The dark red colour morphotype
of A. constrictum was most common (87%, n = 279) followed by the yellow, striped, and then spotted varieties. The population was comprised mainly of large (≥10 mm
disc diam) individuals, and juveniles were rarely encountered, indicating low rates of recruitment or a high mortality of
recruits. Disc-diameter data gathered from this and previous studies indicated that growth in A. constrictum is initially rapid, with individuals reaching a disc diameter of 15 mm in ≃2.5 yr; growth decreases with age, as in other
deep-sea ophiuroids. Growth rate within years, however, was not constant, with faster growth in the spring/summer. Maximum
size for A. constrictum is reached in ≃8 yr at ˜23 mm disc diam. Anecdotal evidence indicates that A. constrictum may not be confined solely to black coral colonies.
Received: 25 September 1996 / Accepted: 16 October 1996 相似文献
2.
Coral bleaching (the loss of symbiotic dinoflagellates from reef-building corals) is most frequently caused by high-light and temperature conditions. We exposed the explants of the hermatypic coral Stylophora pistillata to four combinations of light and temperature in late spring and also in late summer. During mid-summer, two NOAA bleaching warnings were issued for Heron Island reef (Southern Great Barrier Reef, Australia) when sea temperature exceeded the NOAA bleaching threshold, and a ‘mild’ (in terms of the whole coral community) bleaching event occurred, resulting in widespread S. pistillata bleaching and mortality. Symbiotic dinoflagellate biomass decreased by more than half from late spring to late summer (from 2.5×106 to 0.8×106 dinoflagellates cm2 coral tissue), and those dinoflagellates that remained after summer became photoinhibited more readily (dark-adapted F
V : F
M decreased to (0.3 compared with 0.4 in spring), and died in greater numbers (up to 17% dinoflagellate mortality compared with 5% in the spring) when exposed to artificially elevated light and temperature. Adding exogenous antioxidants (d-mannitol and l-ascorbic acid) to the water surrounding the coral had no clear effect on either photoinhibition or symbiont mortality. These data show that light and temperature stress cause mortality of the dinoflagellate symbionts within the coral, and that susceptibility to light and temperature stress is strongly related to coral condition. Photoinhibitory mechanisms are clearly involved, and will increase through a positive feedback mechanism: symbiont loss promotes further symbiont loss as the light microenvironment becomes progressively harsher. 相似文献
3.
N. O. G. Jørgensen 《Marine Biology》1979,52(1):45-52
For valine uptake by the polychaete Nereis virens Sars, the kinetic constants were: V
max=355 nmol g-1 fresh weight h-1, K
m=20 M. Leucine and some other amino acids acted as partial inhibitors of valine uptake. Valine uptake rate was 78% higher at 21.5 S than at 14 S. The major portion of valine absorbed by the polychaete could be extracted as free valine, with 6.5 to 15.6% being respired, and 3.6 to 9.5% incorporated into proteins. Calculations indicate that 7 to 12% of the metabolism of N. virens may be sustained by uptake of glycine and aspartic acid from natural concentrations. It is suggested that uptake of amino acids by this worm is important in the nitrogen cycling of marine sediments. 相似文献
4.
L. J. McCook 《Marine Biology》1997,129(4):713-722
A combination of small-scale transplants and herbivore exclusion was used to test the importance of herbivory, physiological
tolerance limits, and recruitment and dispersal in regulating the distribution and abundance of the genus Sargassum on two nearshore fringing reefs of the central Great Barrier Reef, during 1992/1993. Sargassum (predominantly S. oligocystum and S. tenerrimum) were transplanted from reef-flat zones where they normally grow, to a seaward coral zone where they are not normally found.
At Great Palm Island, coral-zone transplants only survived if protected from herbivores. At Brook Island, survival of uncaged
coral-zone transplants was more variable but not significantly lower than plants returned to the Sargassum zone. Thus herbivory may be a major cause of the zonation patterns of adult Sargassum on these fringing reefs, but the importance of this factor varies between and within reefs. Since protected Sargassum survived and grew for up to 6 mo in the coral zone, the adult algae are not physiologically limited by any physical or chemical
differences between zones. However, Sargassum recruitment to the coral zone was very low (mean 2.7 recruits m−2 over 13 mo), and was not significantly affected by herbivores. Since rates of herbivory were relatively slow, effective exclusion
of Sargassum from the coral zone by herbivores may depend on low recruitment of the algae. In a broader context, the distribution of Sargassum may depend on the combined spatial patterns of herbivory and recruitment.
Received: 24 January 1997 / Accepted: 12 May 1997 相似文献
5.
M. Díaz-Jaramillo J. Ribas A. M. da Rocha E. Bay-Smith G. Fillmann R. Barra 《Chemistry and Ecology》2013,29(1):43-48
The objective of this study was to analyse biochemical responses induced by the carbon nanomaterial fullerene (C60) in the polychaete Perinereis gualpensis (Nereididae). The activity of glutathione-S-transferase (GST), glutathione reductase (GR) and glutamate cysteine ligase (GCL), as well as total antioxidant capacity, concentration of glutathione (GSH) and malondialdehyde (TBARS), were analysed. Estuarine worms were maintained in sediments collected at an unpolluted site and spiked with fullerene (3 mg C60·g?1 sediment). A control group was run in parallel. Scanning electron microscope (SEM) images of sediment and fullerene indicated that the size of the carbon nanomaterial should enable it to be ingested by the polychaete. No evidence of oxidative damage (TBARS) was observed in any of the treatments, and the same was true for GSH and GCL measurements (p>0.05). Total antioxidant capacity was higher in the C60 group after 2 and 7 d when compared with the control group (p<0.05), suggesting that fullerene is acting as an antioxidant. The fact that P. gualpensis is an infaunal organism diminishes the chance of fullerene photoexcitation with consequent reactive oxygen species production. Thus, the data indicated an absence of toxic responses mediated by oxidative stress in estuarine worms exposed to C60 mixed in sediments. 相似文献
6.
N. M. Otway 《Marine Biology》1994,121(1):105-116
Populations of two chitons, Onithochiton quercinus (Gould, 1846) and Plaxiphora albida (Blainville, 1825) were sampled at five sites in the low-shore algal community at Cape Banks, New South Wales, Australia, from January 1985 to February 1988. Both species were abundant, reaching densities of 96 and 45 m-2, respectively and grew to 80 mm in length. O. quercinus and P. albida were found on the solitary ascidian Pyura stolonifera and on the substratum in amongst the foliose macroalgae which dominate this community. Size-frequency data were used to estimate the rates of growth, mortality and longevity, and time of recruitment. Growth of both species was rapid for the first 3 yr and slowed thereafter. O. quercinus and Plaxiphora albida had similar longevities and were estimated to live for at least 6 yr. Reproductive samples were also collected to identify when sexual maturity occurred, to clarify the reproductive periodicity, and to examine the sex ratios of the two species. Both species spawned over a discrete period in early autumn and there was no evidence of the bi-annual spawning reported in a previous study. Recruitment of O. quercinus and P. albida occurred during autumn, but recruits could not be quantified owing to their cryptic nature. The microhabitats occupied by the recruits of both species included the empty shells of the barnacle Austromegabalanus nigrescens, the spaces between the calcareous tubes of the polychaete Galeolaria caespitosa, and the space amongst the algae on Pyura stolonifera. Both species reached reproductive maturity at 2 yr of age. The sex ratios of both species were consistent with the results of a previous study: P. quercinus had a sex ratio of almost 2:1 biased in favour of males, and Plaxiphora albida exhibited a sex ratio of 1:1. The study suggested that populations of O. quercinus and P. albida could persist in the low-shore algal community in the absence of recruitment. This, together with their large size and consumption of macroalgae suggests that they have the potential to affect the structure and dynamics of this intertidal community. 相似文献
7.
W. C. Renfro 《Marine Biology》1973,21(4):305-316
Silty marine sediments spiked with 65Zn lose only small fractions of their radioactivity when exposed to slowly flowing seawater for several weeks. However, polychaete worms (Nereis diversicolor), burrowing through the sediment, cause 65Zn losses 3 to 7 times higher than in sediment without worms. Long-term experiments on the uptake and loss of 65Zn by the polychaete Hermione hystrix indicate that 60 or more days exposure are required for this worm to approach steady state with 65Zn in the sediment. Biological half-life estimates for 65Zn accumulated from sediment by H. hystrix are extremely variable (52 to 197 days), depending on the loss-time interval chosen for the calculation. Following 5 days exposure to 16 cm3 of radioactive sediment, N. diversicolor individuals contained an average of 0.2% of the total 65Zn in the sediment. When these worms were transferred to non-radioactive sediment, estimates of biological half-life for 65Zn averaged 14 to 17 days during the loss period Day 3 to Day 15. Based on these experimental results, it is estimated that a population of N. diversicolor could cause an annual loss of 3% or more of the 65Zn in the upper 2 cm of the sediment of a hypothetical radioactive estuary. 相似文献
8.
Elevated sea surface temperatures in the late 1990s were associated with widespread coral mortality in the Arabian Gulf, particularly
in Acropora dominated areas. This study investigates the composition, condition, and recruitment patterns of coral communities in Saih
Al-Shaib, Dubai, United Arab Emirates, a decade after mass bleaching. Five statistically distinct communities were identified
by cluster analysis, with grouping optimized from 17 significant indicator species. Overall, 25 species of scleractinian coral
were observed, representing 35 ± 1.6% coral cover. Densities of recruits were low (0.8 ± 0.2 m−2), and composition generally reflected that of the surrounding adult community. Ten years after mass mortality, Acropora dominated assemblages were observed in three of the six sites examined and coral cover (41.9 ± 2.5%) was double post-bleaching
cover. One shallow near-shore site appears to have had recovery of Acropora reset by a further bleaching event in 2002. However, the prevalence of young Acropora colonies here indicates that recovery may recur in several years. One area formerly dominated by Acropora is now dominated by faviids and poritids, with adult and juvenile composition suggesting this dominance shift is likely to
persist. Porites lutea and Porites harrisoni dominated communities were negligibly impacted by the bleaching events, and the limited change in coral cover and composition
in intervening years likely results from slow growth and low recruitment. Despite strong recovery of several dominant Acropora species, five formerly common species from this area were not observed suggesting local extinction. Dubai coral communities
exhibit both resistance and resilience to elevated sea temperatures. The conservation of these patch reefs is warranted given
the predicted increase in bleaching events, and the role that these communities may play in regional recovery. 相似文献
9.
P. A. Farrant 《Marine Biology》1987,96(3):401-407
Populations of over 100 colonies of Capnella gaboensis Verseveldt, 1977 at each of four study sites in Sydney Harbour were monitored for recruitment, survival, and mortality from October 1982 to November 1984. Larval settlement and survival were observed in the laboratory. Successful in situ larval settlement of C. gaboensis was estimated to be in the order of 0.26%. The predominant mode of recruitment was from larvae. Asexual recruitment resulted only from the fission of large colonies, and not by fragmentation or by stolon development. Mortality of newly settled C. gaboensis in situ during their first year was estimated to be around 99.75%. For colonies more than 1 yr old, mortality was highest amongst juveniles. After colonies reach about 3 yr of age, they have a high expectation of further life, until they reach about 15 yr of age; life expectancy declines each year thereafter. These estimates of life expectancy are based upon the conservative assumption that the largest colonies are about 20 yr old. The likely causes of mortality for colonies in the field are: predation by urchins, ovulids and nudibranchs; abrasion by kelp; and overgrowth by algae and sponges. The causes of mortality for larvae and recruits in the field, however, can be predicted only on the basis of laboratory studies and observations of field conditions. 相似文献
10.
Jessica Haapkylä Adrian S. Seymour Orit Barneah Itzchak Brickner Sebastian Hennige David Suggett David Smith 《Marine Biology》2009,156(5):1021-1027
This is the first quantitative study on the prevalence of epizoic Waminoa sp. acoel worms and their association with corals in the Wakatobi Marine National Park (WMNP), South-East Sulawesi, Indonesia.
Three replicate transects were laid on the reef crest, flat and slope at six sites in 2006 and eight sites in 2007. Four of
the sites were common in both years. In total 69 transects were surveyed in 2006, and 87 transects in 2007. A total of 4.8%
of all observed hard corals were associated with acoel worms in 2006 and 2.6% of hard and soft corals in 2007. Acoels were
present on 16 and 21 of the coral taxa studied in 2006 and 2007 respectively. The worms were strongly associated with the
azooxanthellate coral Tubastrea spp. and were rare or absent on the most abundant coral genera Montipora and Porites. The mean number of corals having acoels was highest on reef slopes, whereas acoels were virtually absent on reef flats. Corals
that had a high and a medium cover of worms were more common in 2007 than in 2006. No significant trend in the adaptation
of the zooxanthellae of Waminoa sp. to different depths at different sites was revealed. The impact of the worm on the coral is unknown, but high numbers
may have a shading effect and a negative impact on the coral’s photophysiology. This acoel merits more study of its life cycle,
its photophysiology, and its impact on its host corals.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
11.
Recruitment rates of stony corals to artificial substrates were monitored for 2 years at 20 sites along the coast of Eilat, northern Red Sea, to compare with those recorded at other coral reef locations and to assess variation in recruitment at several spatial scales. Coral recruitment was low compared to that observed on the Great Barrier Reef in Australia, but was similar to levels reported from other high-latitude reef locations. Pocilloporids were the most abundant coral recruits in all seasons. Recruitment was twofold higher during the first year than during the second year of study. There was considerable spatial variability, with the largest proportion of variance, apart from the error term, attributable to differences between sites, at a scale of 102 m. Spearmans ranked correlation showed consistency in spatial patterns of recruitment of pocilloporid corals between years, but not of acroporid corals. During spring, when only the brooding pocilloporid coral Stylophora pistillata reproduces at this locality, most coral recruitment occurred at central and southern sites adjacent to well-developed coral reefs. During summer, recruitment patterns varied significantly between years, with wide variation in the recruitment of broadcasting acroporid corals at northern sites located distant from coral reefs. Settlement was low at all sites during autumn and winter. This work is the first detailed analysis of coral recruitment patterns in the Red Sea, and contributes to the understanding of the spatial and temporal scales of variation in this important reef process.Communicated by O. Kinne, Oldendorf/Luhe 相似文献
12.
P. Baelde 《Marine Biology》1994,118(4):617-625
The MULTIFAN method of Fournier et al. was used to analyse a series of monthly length-frequency distributions of deep-water royal red prawns (Haliporoides sibogae de Man, 1907, Solenoceridae) for the estimation of growth, mortality and yield-per-recruit. Length data were collected from commercial catches made between Latitude 33° and 35°S from November 1988 to May 1990. MULTIFAN distinguished six cohorts in the royal red prawn population, aged at 6 mo intervals from about 1.5 to 4 yr. Most prawns were between 2 and 3 yr of age. Females and males were fully recruited at 23.1 and 21.5 mm carapace length (CL) respectively, when about 2 yr old. Females grew faster and reached larger sizes at age than males (growth coefficient, K=0.37 yr-1 and asymptotic length, L
=48.3 mm CL for females, and K=0.49 yr-1 and L
=33.5 mm CL for males). Total mortality (Z) was estimated at 1.6 and 1.2 yr-1 for females and males, respectively. Approximate values for natural mortality (M) ranged from 0.6 to 0.7 yr-1 for females, and from 0.4 to 0.8 yr-1 for males. Analysis of yield-per-recruit suggested that while the current yield could possibly be increased by decreasing the length at first capture (L
c
), there seems to be little potential for an increase in yield from increased fishing effort in the area currently fished. 相似文献
13.
J. M. Aldenhoven 《Marine Biology》1986,92(2):237-244
Mortality rates of the coral reef fish Centropyge bicolor were based on the disappearance of known individual fish. Data were collected over three years from 1978 at four sites around Lizard Island, Queensland, Australia. To measure disappearance, membership of 36 harems (comprising about 150 fish at any one time) was determined at bimonthly intervals. Mortality rates varied significantly among the four study areas. A tenfold difference in mean mortality occurred between two of the areas. The ranking of areas according to mortality rate was similar for 1978–1979 and 1979–1980. The ranking of areas was again similar for 1980–1984 when mortality rates were determined from an additional census in June 1984. Average further life-expectancy of mature fish based on mortality rates varied from 1 yr in one study area to 5 to 13 yr in a different area. 相似文献
14.
R. C. Highsmith 《Marine Biology》1980,56(2):155-162
The burrowing bivalve Lithophaga curta is abundant (8 to 9 per 100 cm2) in the encrusting, hermatypic coral Montipora berryi at Enewetak; this is the first report of L. curta colonizing living coral. Conversely, larvae of M. berryi appear to settle in empty bivalve burrows, tentatively identified as those of L. curta, located in dead M. berryi. Several hypotheses are suggested on the adaptive significance of substrate selection by larvae of both species and an overall hypothesis of reciprocal recruitment, describing the dynamic aspects of this apparently co-evolved relationship, is proposed. 相似文献
15.
The polychaete Nereis diversicolor O. F. Müller was exposed to marine sediments which had been contaminated with 55Fe either through the testing of nuclear devices or by the release of liquid waste effluent from a nuclear fuel reprocessing plant. The amount of 55Fe taken up reached a concentration in the worms about 6% of the concentration in both types of sediment. Bioavailability of 55Fe was shown to depend on its concentration in sediment and not on sediment type, stable iron concentration, or the source of contamination. N. diversicolor may not extract from sediment the same fraction of 55Fe as does 0.1N HCl and caution should be exercised in using such measurements to represent the bioavailable fraction. 相似文献
16.
Population dynamics and reproductive biology of the commensal isopod Colidotea rostrata (Crustacea: Isopoda: Idoteidae) 总被引:2,自引:0,他引:2
T. D. Stebbins 《Marine Biology》1989,101(3):329-337
Colidotea rostrata (Benedict, 1898) is the only known commensal idoteid isopod, living on and mimicking the color of two northeastern Pacific sea urchins of the genus Strongylocentrotus. The population dynamics and reproductive biology of C. rostrata on its host urchins were studied at a low rocky intertidal area in southern California (33°40N; 118°30W) from December 1984 to December 1986. Isopod populations remained relatively stable throughout the 2 yr study, with isopods inhabiting an average of 56.1% of the urchins at 6.1±0.6 (x±2 SE) isopods per urchin. Female isopods reach sexual maturity at a length of 6.8 mm. Fecundity in C. rostrata averaged 11.8±0.9 (x±2 SE) embryos per brood, and increased with female body size. Breeding occurs all year long in C. rostrata, with a main reproductive period between the warmer spring and summer months. Newly released mancas and juvenile isopods were present during all months of the study. C. rostrata differs from the free-living Idoteidae in its smaller maximum size, reduced fecundity, 1:1 sex ratio, and low juvenile mortality. These features may represent adaptations to a commensal life style that reflect a reduced mortality pressure on these isopods. 相似文献
17.
Mucus released by scleractinian corals can act as an important energy and nutrient carrier in coral reef ecosystems, and a
distinct isotopic signature would allow following the fate of this material. This study investigates the natural C and N stable
isotopic signatures of mucus released by four scleractinian coral genera (Acropora, Fungia, Pocillopora and Stylophora) in comparison with those of suspended particulate organic matter (POM) in seawater of a Northern Red Sea fringing coral
reef near Aqaba, Jordan. The natural δ13C and δ15N signatures of coral mucus differed significantly from seawater POM for the majority of seasonal comparisons, but were inappropriate
for explicit tracing of mucus in the coral reef food web. Thus, a labeling technique using stable isotope tracers (13C and 15N) was developed that produced δ13C values of up to 122 ± 5‰ (mean ± SE) and δ15N of up to 2,100 ± 151‰ in mucus exuded by Fungia corals. 13C and 15N-enriched compounds were rapidly (within 3 h) and light-dependently transferred from the endosymbiotic zooxanthellae to the
mucus-producing coral host. The traceability of 15N-labeled mucus was examined by evaluating its uptake and potential utilization by epizoic acoelomorph Waminoa worms naturally occurring on a range of scleractinian coral taxa. This tracer experiment resulted in uptake of coral mucus
by the coral-associated acoelomorphs and further demonstrated the possibility to trace stable isotope-labeled coral mucus
by revealing a new trophic pathway in coral reef ecosystems. 相似文献
18.
Two experiments were conducted to determine the effect of the type of sediment organic matter and geochemical conditions during diagenesis on the stable carbon isotope ratio 13C of the deposit-feeding polychaete worms Capitella spp. Laboratory experiments showed 13C values of-13.5 to-13.9%. for worms grown on fresh and aged kelp, Macrocystis pyrifera. Field experiments on worms in the Santa Barbara Channel, California (USA), in 1986 revealed more negative 13C values (to-19%.) when oil and kelp were added to sediments. The more negative values suggest the incorporation of oil carbon into worm tissues, supporting previous indications of the importance of hydrocarbons in food webs near oil seeps. 相似文献
19.
Deposit-feeders can respond to seasonal fluctuations in food concentration both functionally (e.g. by adjusting feeding rates)
and physiologically (e.g. by changing the concentration of bacteriolytic agents in gut fluids). Laboratory feeding experiments
were carried out (11 to 21 July 1997) with the arenicolid polychaete worm Abarenicola pacifica (Healy and Wells). Objectives were to test for separate and interactive effects of sediment food concentration and temperature
(6, 11, and 16 °C) on deposit-feeder functional (feeding rates) and physiological (bacteriolytic activity of gut fluids) responses.
Food concentration was varied experimentally using sieved (1 mm) natural sediments (Md φ=2.00; 0.6% organic) mixed with combusted
(500 °C, 8 h) sediments for final concentrations of 25, 50, and 100% natural sediment. Sediment food quality was measured
as: (1) bioavailable amino acids (EHAA), (2) chlorophyll a (chl a), and (3) bacterial abundance. Feeding rates were inferred from egestion rates (ER, g h−1) and analyzed with respect to worm size. Bacteriolytic activity of midgut fluids was assayed turbidimetrically against two
bacterial isolates, after worms had fed on experimental sediments for 15 d. Temperature and food concentration both significantly
affected feeding rates, with maxima occurring at 50 and 100% natural sediment mixtures, and at high (16 °C) temperature. ER
was positively, but not significantly correlated with EHAA and chl a; a positive, significant correlation was detected between ER and sediment bacterial abundance. Overall, functional responses
agreed with earlier compensatory intake models for deposit-feeders. However, the size and direction of these responses was
temperature-sensitive, suggesting that these models need to be adjusted for changes in absorption rates. No effects of ambient
temperature or food concentration on bacteriolytic rates were observed, possibly due to compensatory mechanisms or the presence
of multiple bacteriolytic agents in gut fluids.
Received: 28 June 1999 / Accepted: 14 March 2000 相似文献
20.
Recruitment variability plays a critical role in determining local population densities of benthic organisms, but extreme
vulnerability at the onset of juvenile life is a trait that is largely responsible for population survivorship trends. The
aim of the present study was to determine the role of juvenile recruitment in the population structure of Necora puber. Juveniles of N. puber were collected from the lower intertidal of rocky shores of Plymouth Sound (southwest coast of the UK) and monthly size–frequency
distribution were used to determine the dynamics and the growth of the population. The parameters of the von Bertalanffy growth
function were estimated (K=0.281 year−1; t
0=0.043; C=0.103; and t
s=0.268) assuming a L
∞=105 mm. Growth was markedly seasonal and present results indicated a slower juvenile growth rate than described previously
for N. puber. The recruitment period was extensive and was two times higher in 2001 than in 2000 at the start of the 1+ year, but levelled
off at the end of the 1+ year class on three of the four shores studied. Instantaneous mortality as high as 5.1 year−1(99.4% year−1) was observed during the higher recruitment year. Early juvenile mortality appears to be density dependent and a demographic
bottleneck appears to limit the number of juveniles on some shores. 相似文献