Survival Of Juvenile Corals Research Articles

Density, diversity, and survival of juvenile corals on reefs of Zanzibar, Tanzania

Density, diversity, and survival of juvenile corals on reefs of Zanzibar, Tanzania

Community of juvenile hard corals (Scleractinia) in different geomorphological type and reef benthic communities

Juvenile corals are an important stage in the life history and demographics of coral populations in nature however, their survival is influenced by the physical environment and benthic coral reef communities. The study of juvenile coral communities with a maximum size of 10 cm on the reefs of Pulau Weh, Sabang, Aceh was conducted to observe juvenile coral communities and determine their relationship with geomorphological types and benthic reefs communities. A total of 9 sites with 72 sampling squares were distributed in different geomorphological; tectonic type with hard substrates of lava and limestone, volcanic type with predominantly sand substrate, and dead coral with algae with the presence of hot springs in the vicinity. In total, we found 25 genera of juvenile corals from 12 families, and the abundance reached 449 colonies with an average of 37.41 colonies per site. The mean density was 6.66 ± 5.99 colonies/m2 (±SD) and varied significantly between sites (p=4.878-7; <0.05), which was dominated by the genera Porites, Pavona, Acropora, Montipora, and Favia. Live coral cover (HC), dead coral algae (DCA), and hard rock substrate (RK) did not affect, however rubble coral (R) was significantly affected (p=1.9-2; <0.05). Geomorphological conditions and benthic reef cover did not show a significant effect (p = 0.48; < 0.05), although juvenile corals were very common and better in the tectonic type than the volcanic type. The survival of juvenile corals was low, where the smaller size was significantly high compared to the larger size (p=4.5-5; <0.05). Our study provides up-to-date information and data on juvenile coral communities based on geomorphological conditions and local benthic reef communities.

First Report of Potential Coral Disease in the Coral Hatchery of Thailand

In this study, coral disease was first reported in the coral hatchery in Thailand. Disease were usually found on corals aged two to five years old during the months of November to December of each year. To identify bacterial strains, culture-based methods for strain isolation and molecular techniques of the 16S rRNA gene analysis were used. The resuts showed that the dominant genera of bacteria in diseased corals were Vibrio spp. (comprising 41.01% of the isolates). The occurrence of the disease in the coral hatchery can have a significant effect on the health and survival of juvenile corals before being transplanted to natural reefs for restoration.

Latitudinal variation in growth and survival of juvenile corals in the West and South Pacific

Latitudinal variation in growth and survival of juvenile corals in the West and South Pacific

INFLUENCE OF MINERAL ACCRETION INDUCED BY ELECTRIC CURRENT ON THE SETTLEMENT AND GROWTH OF THE SCLERACTINIAN CORAL POCILLOPORA DAMICORNIS (CNIDARIA, ANTHOZOA, HEXACORALLIA)

The effect of mineral accretion induced by electric current on settlement, growth, and survival of planula larvae and juvenile corals of Pocillopora damicornis was examined by both laboratory and field experiments. The laboratory experiment showed that the numbers of larvae settling on tiles with coralline algae and steel plates encrusted with limestone under no electric current condition were higher than that of other conditions. In the field, the highest survival rates of juvenile corals occurred under the lowest electric current density. However, there was no difference on the growth of juvenile corals between different electric current levels. The mineral accretion could potentially be used to enhance survival of juvenile corals for coral rehabilitation purpose.

The Roles and Interactions of Symbiont, Host and Environment in Defining Coral Fitness

BackgroundReef-building corals live in symbiosis with a diverse range of dinoflagellate algae (genus Symbiodinium) that differentially influence the fitness of the coral holobiont. The comparative role of symbiont type in holobiont fitness in relation to host genotype or the environment, however, is largely unknown. We addressed this knowledge gap by manipulating host-symbiont combinations and comparing growth, survival and thermal tolerance among the resultant holobionts in different environments.Methodology/Principal FindingsOffspring of the coral, Acropora millepora, from two thermally contrasting locations, were experimentally infected with one of six Symbiodinium types, which spanned three phylogenetic clades (A, C and D), and then outplanted to the two parental field locations (central and southern inshore Great Barrier Reef, Australia). Growth and survival of juvenile corals were monitored for 31–35 weeks, after which their thermo-tolerance was experimentally assessed. Our results showed that: (1) Symbiodinium type was the most important predictor of holobiont fitness, as measured by growth, survival, and thermo-tolerance; (2) growth and survival, but not heat-tolerance, were also affected by local environmental conditions; and (3) host population had little to no effect on holobiont fitness. Furthermore, coral-algal associations were established with symbiont types belonging to clades A, C and D, but three out of four symbiont types belonging to clade C failed to establish a symbiosis. Associations with clade A had the lowest fitness and were unstable in the field. Lastly, Symbiodinium types C1 and D were found to be relatively thermo-tolerant, with type D conferring the highest tolerance in A. millepora.Conclusions/SignificanceThese results highlight the complex interactions that occur between the coral host, the algal symbiont, and the environment to shape the fitness of the coral holobiont. An improved understanding of the factors affecting coral holobiont fitness will assist in predicting the responses of corals to global climate change.

Coral recruitment in blasted and unblasted sites in Indonesia: assessing rehabilitation potential

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 269:131-139 (2004) - doi:10.3354/meps269131 Coral recruitment in blasted and unblasted sites in Indonesia: assessing rehabilitation potential Helen E. Fox* Department of Integrative Biology, University of California, Berkeley 94720-3140, California, USA Present address: Hawaii Institute of Marine Biology, PO Box 1346, Kaneohe, Hawaii 96744, USA *Email: hfox@hawaii.edu ABSTRACT: Widespread blast fishing destroys living scleractinian corals and creates vast fields of shattered coral rubble that can only recover to coral dominance through a successional process that includes coral recruitment. Given the extent of damaged areas on many SE Asian reefs, successful recruitment and survival of juvenile corals will be important components of either natural recovery or human-assisted rehabilitation. Early scleractinian coral recruitment to tiles was assessed in blasted and unblasted sites in Komodo National Park, Indonesia, from 1998 to 2000. A total of 6530 corals recruited to 527 tiles (each 400 cm2), primarily of the families Acroporidae (27.1%), Pocilloporidae (44.7%) and Poritidae (12%). Acroporids settled primarily during NW monsoon months (October-April), while pocilloporids and poritids settled year-round. Standardized recruitment rates averaged from 285 to 772 spat m-2 yr-1 across all sites, with a site maximum of 2663 spat m-2 yr-1. While significant spatial and temporal variation was detected across sites and seasons, no significant difference in abundance of coral spat was found between blasted and unblasted sites. Results from this study suggest that these blasted sites are not recruitment-limited, and that failure of corals to recover in rubble fields is due to post-settlement mortality. KEY WORDS: Coral settlement · Recruitment · Recovery · Dynamite fishing · Blast fishing · Indonesia Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 269. Online publication date: March 25, 2004 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2004 Inter-Research.

Serial patterns of biodiversity change in corals across shallow reef flats in Ko Phuket, Thailand, due to the effects of local (sedimentation) and regional (climatic) perturbations

A 17-year monitoring programme of reef flats at Ko Phuket, Thailand afforded an opportunity to evaluate both univariate and multivariate measures of environmental stress in an assessment of change on coral reef ecosystems. The sites at Ko Phuket suffered the effects of dredging in 1986–1987 and then anomalously low sea levels in 1997–1998 as a result of climate-related events in the Indian Ocean. Univariate measures of species diversity and taxonomic distinctness (Δ*) increased across the reef flat, reflecting the greater effects of physical stresses on the inner reef flats (compared with outer reef flats) at all sites, with more congeneric species present on the inner reef and more confamilial species on the outer reef. Multivariate measures showed a clear breakdown in seriation patterns at all sites during the dredging in 1987 and in 1998, as a result of earlier negative sea-level anomalies. Recovery from environmental disturbances was obvious within 12 months in each case. The domination of the reefs by massive coral species, which are physiologically adapted to intertidal living and which display partial rather than total colony mortality, may be a factor contributing to the apparent resilience of the reef flats together with continued recruitment and survival of juvenile corals during adverse environmental conditions. Elevated sea temperatures and extensive bleaching of corals in 1991, 1995, and 1998 had no effect upon coral community measures, with many corals recovering their zooxanthellae numbers within 3–5 months of the bleaching events.

Coral Reef Recovery on Guam (Micronesia) After Catastrophic Predation by Acanthaster Planci.

At Tanguisson Reef, Guam, in 1968-1969 a population explosion of the coral-eating sea star Acanthaster planci devastated the coral community. In the wake of this predation, coral species richness, density, and cover were drastically reduced, and the species composition was altered. In two of three reef zones examined, < 1% coral cover remained. At the time of disturbance, some considered the magnitude of this and similar Acanthaster disturbances unprecedented, and predicted long recovery times because reefs were viewed as mature, stable communities. This major disturbance offered an opportunity to study the processes and rate of community recovery. Using the data from previous studies in 1970, 1971, and 1974, and my data from 1980-1981, I present a long-term analysis of coral community development. I have focused on coral recruitment, survivorship, and species settlement patterns in relationship to the remnant surviving population. The preference of Acanthaster planci for certain prey (e.g., Montipora and Acropora) shifted the species composition to one in which nonpreferred prey predominated (e.g., Porites and Leptastrea). The predominance of nonpreferred prey was short-lived, and by 1980, preferred prey were the primary colonists of two zones. The three biological zones (reef front, submarine terrace, and seaward slope) had their own characteristic species assemblages soon after the disturbance. Nonrandom recruitment or survival of juvenile corals (diameter ≤ 4 cm) established these zones. Although the percentage of juvenile corals fell throughout the survey, their highest density was reached after adult colonies were established. In 1980, of the 34 species examined, 79% showed a significant coefficient of association between adult and juvenile conspecifics. This association caused clumped species dispersion patterns to develop within zones. As the result of recruitment, species diversity rose from 84 species in 1970 to 154 species in 1981. As surviving corals and new recruits developed, the distribution of coral growth forms became more diversified. There was a drastic increase in coral cover (e.g., submarine terrace zone, 0.9% in 1970 to 65% in 1981). This increase in cover corresponded to an increase in size and number of the coral colonies In 12 yr, species richness, cover, and composition reached or exceeded measurements of comparable reefs before the disturbance. The recovery occurred faster than predicted by a stable equilibrium model because long-term successional changes were not required. Recovery was accelerated because Acanthaster did not destroy the structural integrity of reef framework. This rapid recovery from a natural disturbance demonstrates that some coral communities have a greater resilience than was once believed.

Mortality and growth of juvenile coral Pocillopora damicornis (Linnaeus)

Early mortality in cohortsof the coral Pocillopora damicornis (Linnaeus) was monitored under experimental conditions on a reef in order to evaluate effects of sedimentation, grazing, predation and competition. Corals that settled in dishes in the laboratory were placed on the reef flat about 3 days after metamorphosis. Six different conditions were tested in each series of experiments: orientation of dishes (upward, vertical and downward) by with and without protection against potential grazers by covering the dish with a net. Survival of juvenile corals on both protected and unprotected dishes facing upward was lower than in the vertical or downward direction. Under the vertical facing and protected conditions, algal growth was more intensive and algae trapped sediment; mortality of juvenile corals by algae and sedimentation increased gradually. In the uprotected and vertical conditions, algal growth on the surface was removed constantly by grazing invertebrates and fishes and the juvenile corals were removed or killed as well. On the downward facing dishes, survivorship of juveniles was relatively high in both protected and unprotected conditions. This habitat attracted many sessile animals that killed some juveniles by competition. Thus, juvenile corals survived better in experimentally manipulated microhabitats not affected by direct sedimentation, not exposed to direct grazing activity, and not occupied by rapidly growing filamentous algae.