Coral Settlement Research Articles

First observations of deep-sea coral reefs along the Angola margin

The West African continental slope is an important theatre for geological survey prospecting and drilling for hydrocarbons but little is known about local deep-sea biological communities at these depths. While shallow-water reefs are common and well-known features in the tropics, only few records of deep-water corals exist at low latitudes, and most of them have been reported by historical oceanographic cruises undertaking circum-navigations of the world. This study, based on a multidisciplinary approach, presents a description of newly discovered deep-water coral reef communities along the Angola margin. Data from ROV, multibeam bathymetry, side-scan sonar and seismics from a deep-towed acoustic system (SAR) were used to describe the morphology of the coral mounds and their relationship with the local geological setting. The reef-building scleractinian coral Lophelia pertusa has colonised carbonate mounds that reach heights of ca. 30 m and follow an orientation that is correlated with salt tectonic processes. Recent erosion is suggested as a process that influences the shape of the mounds. Sixteen fish taxa were identified during the ROV video surveys, with some of them likely to have a strong affinity with dense-living corals. The species observed belong to families commonly associated with deep-water corals (i.e. Sebastidae, Berycidae, Lophiidae and Chaunacidae), except an abundant species belonging to the family Zoarcidae, rarely observed in this type of environment. Lucinidae shells were found around mounds. As this bivalve family is indicative of reduced sediment and generally associated with cold-seep environments, this finding could revive the debate over the relationship between the distribution of cold-water coral habitat and gas seeps. However, there is no present-day nutritional relationship between living coral and chemosynthetic-derived biomass. The possible role of fluid expulsion in carbonate precipitation acting as the first step for coral colonisation is nevertheless discussed.

Development of a coastal environment assessment system using coral recruitment

A new method for assessing coastal environments using the reproduction potential of corals has been developed and examined in situ. Six assessment racks were deployed before the full moon of May 2006 at three sites located around a river outlet in Nagura Bay, Ishigaki Is. and at one control location in Sekisei Lagoon. Each rack was equipped with two marine blocks (MB) containing 378 holes, two cases of coral settlement devices (CSDs), each containing 120 CSDs, and a water temperature logger. Assessment was based on recruitment of Acropora due to mass spawning. After 4 months of deployment, the surface of assessment racks showed apparent biofouling depending on sites mainly by algal settlement on the surfaces. Almost all the holes of the MBs were partly occupied, mainly by turf algae. Nagura Bay was thought likely to be an “unhealthy” coral reef due to runoff from land. However, our assessment showed that there were 0.85 corals per CSD in the Bay, compared with 0.51 in Sekisei Lagoon, indicating that coral larvae supply is not the cause of the unhealthy condition of corals in the Nagura Bay.

Effects of CO2-driven ocean acidification on the early developmental stages of invertebrates

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 373:275-284 (2008) - DOI: https://doi.org/10.3354/meps07802 Contribution to the Theme Section ‘Effects of ocean acidification on marine ecosystems’ Effects of CO2-driven ocean acidification on the early developmental stages of invertebrates Haruko Kurihara* Institute for East China Sea Research, Nagasaki University, 1551-7 Tairamachi, Nagasaki 851-2213, Japan *Email: harukoku@e-mail.jp ABSTRACT: CO2 emissions arising from the burning of fossil fuels have altered seawater chemistry far more rapidly than the Earth has previously experienced, and the rate and extent of this change are expected to affect shallow water marine organisms. The increased CO2 diffuses from the atmosphere into ocean surface waters, resulting in increased partial pressure of CO2, and reduced [CO32–] and pH. The CO2-driven ocean acidification leads to a decrease in calcium carbonate (CaCO3) saturation state in the ocean surface waters and has potential impacts on calcifiers. The present study focuses on the effects of ocean acidification on early developmental and reproductive stages of calcifiers, both of which are believed to be the most vulnerable stages to environmental change within a life cycle. Laboratory experiments revealed that ocean acidification has negative impacts on the fertilization, cleavage, larva, settlement and reproductive stages of several marine calcifiers, including echinoderm, bivalve, coral and crustacean species. There appear to be significant ontogenetic impacts and species-specific differences in tolerance to the high CO2 levels. The conclusion is that future changes in ocean acidity will potentially impact the population size and dynamics, as well as the community structure of calcifiers, and will therefore have negative impacts on marine ecosystems. Further studies are needed to evaluate the potential impacts on non-calcifiers, as well as the synergistic impacts of ocean acidification and climate change. Studies should also focus on the adaptive capability of marine organisms, which will be crucial to the ability to forecast how marine organisms and ecosystems will respond to the world’s oceans as they warm and acidify. KEY WORDS: CO2 · Ocean acidification · Seawater chemistry · Calcifiers · Early development · Reproduction · Rapid environmental change Full text in pdf format PreviousNextCite this article as: Kurihara H (2008) Effects of CO2-driven ocean acidification on the early developmental stages of invertebrates. Mar Ecol Prog Ser 373:275-284. https://doi.org/10.3354/meps07802Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 373. Online publication date: December 23, 2008 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2008 Inter-Research.

Development of ceramic settlement devices for coral reef restoration usingin situsexual reproduction of corals

A ceramic coral settlement device (CSD) was developed to raise juvenile corals in situ in preparation for transplantation. The CSD is designed to be deployed in the water before mass spawning of corals, allowing larvae to settle and grow on the CSD before it is fixed to the reef structure. CSDs were aggregated and fixed on 0.2-m2 frames (either 648 or 720 CSDs per frame) and deployed in the Sekisei Lagoon around the full moons of April and May in 2002. Seven frames were collected in August 2002 and settled corals were counted in the laboratory. The maximum number of coral colonies settled on CSDs in one frame was 617, with 94% belonging to the genus Acropora. The aggregated CSDs successfully functioned as a coral settlement substratum, with more appropriate arrangement of CSDs on the frame, enabling greater exposure to sunlight and currents, which is expected to increase the amount of settlement.

Modelling the local distribution of cold-water corals in relation to bathymetric variables: Adding spatial context to deep-sea video data

Video data and high-resolution multibeam bathymetry were acquired using a Remotely Operated Vehicle (ROV) on the flank of a carbonate mound (∼850 m depth) in the Porcupine Seabight, SW Ireland. The ROV-mounted multibeam system revealed details of bathymetry that were not resolved by ship-borne multibeam survey, but appear to be important in structuring the distribution of the cold-water corals Lophelia pertusa and Madrepora oculata. Quantitative measures of slope, orientation, roughness and curvature were calculated from the ROV multibeam bathymetry data across a range of spatial scales. These parameters were analysed for their ecological relevance to the distribution of the corals and used in an Ecological Niche Factor Analysis (ENFA) to identify the most suitable areas for coral colonisation within the extent of our ROV multibeam data. The suitability map covers an area nine times the size of the area imaged directly by video. Cross-validation of the results with video data indicates that the predictions are reliable. This combined survey and modelling approach offers a comprehensive method for ground-truthing discrete seabed features such as mounds. It provides spatial context to high-resolution deep-water video observations and highlights the importance of bathymetric variables in influencing coral distribution.

DENSITY-DEPENDENT SETTLEMENT AND MORTALITY STRUCTURE THE EARLIEST LIFE PHASES OF A CORAL POPULATION

The local densities of heterospecifics and conspecifics are known to have profound effects on the dynamics of many benthic species, including rates of settlement and early post-settlement survivorship. We described the early life history of the Caribbean coral, Siderastrea radians by tracking the population dynamics from recently settled planulae to juveniles. Through three years of observation, settlement correlated with the abundance of other benthic organisms, principally turf algae (negatively) and crustose coralline algae (positively). In addition, adult density showed independent effects on coral settlement and early post-settlement survivorship. Settlement rates increased across low levels of adult cover and saturated at a maximum around 10% cover. Early post-settlement survivorship decreased with adult cover, revealing structuring density dependence in coral settlers. The earliest life stages of corals are defined by low survivorship, with survivorship increasing appreciably with colony size. However, recent settlers (one-polyp individuals, < 1-year-old) are more likely to grow into two-polyp juveniles than older single polyps (> 1-year-old) that were delayed in their development. The early benthic phase of corals is defined by a severe demographic bottleneck for S. radians, with appreciable density-dependent and density-independent effects on survivorship. For effective management and restoration of globally imperiled coral reefs, we must focus more attention on this little studied, but dynamic, early life history period of corals.

Chemical effects of macroalgae on larval settlement of the broadcast spawning coral Acropora millepora

Recovery of degraded reefs is dependent on the settlement of coral larvae into habitats typically dominated by benthic algae, so that benthic algae may play pivotal roles in coral settlement and reef recovery. Here we demonstrate that waterborne influences of macroalgae could affect coral settlement before larvae contact reef substrata and that such effects vary between macroalgae. We tested for waterborne effects of algae on both pre-settlement behaviour and settlement of larvae of the coral Acropora millepora onto live fragments of the crustose coralline alga Hydrolithon reinboldii. Treatments comprised seawater collected from aquaria that had previously contained 1 of 3 macroalgae common on degraded reefs. The foliose brown macroalga, Lobophora variegata, enhanced coral settlement by 40% relative to substratum control treatments. In contrast, the filamentous green macroalga Chlorodesmis fastigiata ('turtle weed'), hindered coral settlement by delaying settlement of larvae, although final settlement was similar to that in control treatments. Padina sp., a foliose brown macroalga closely related to L. variegata, reduced coral settlement by 30% compared with substratum controls. The demonstration of waterborne effects suggests that macroalgae can influence coral settlement before larvae reach reef substrata, even on a crustose coralline alga known to induce settlement, and even where the immediate settlement location is free of macroalgal cover. These results demonstrate the complexity in the mechanisms underlying the effects that over-abundant macroalgal growth may have on reef recovery. These effects have critical implications for the ecological resilience of coral reefs, especially as climate change increases the frequency and severity of disturbances to reefs.

Analysis of nitric oxide‐cyclic guanosine monophosphate signaling during metamorphosis of the nudibranch Phestilla sibogae Bergh (Gastropoda: Opisthobranchia)

The gas nitric oxide (NO), and in some cases its downstream second messenger, cyclic guanosine monophosphate (cGMP) function in different taxa to regulate the timing of life-history transitions. Increased taxonomic sampling is required to foster conclusions about the evolution and function of NO/cGMP signaling during life-history transitions. We report on the function and localization of NO and cGMP signaling during metamorphosis of the nudibranch Phestilla sibogae. Pharmacological manipulation of NO or cGMP production in larvae modulated responses to a natural settlement cue from the coral Porites compressa in a manner that suggest inhibitory function for NO/cGMP signaling. However, these treatments were not sufficient to induce metamorphosis in the absence of cue, a result unique to this animal. We show that induction of metamorphosis in response to the settlement cue is associated with a reduction in NO production. We documented the expression of putative NO synthase (NOS) and the production of cGMP during larval development and observed no larval cells in which NOS and cGMP were both detected. The production of cGMP in a bilaterally symmetrical group of cells fated to occupy the distal tip of rhinophores is correlated with competence to respond to the coral settlement cue. These results suggest that endogenous NO and cGMP are involved in modulating responses of P. sibogae to a natural settlement cue. We discuss these results with respect to habitat selection and larval ecology.

Patterns of coral larval settlement on lagoon reefs in the Mombasa Marine National Park and Reserve, Kenya

Spatial and temporal patterns of coral larval settlement were studied on 2 lagoon reefs in the Mombasa Marine National Park and Reserve (4°S) from 2003 to 2005, to examine relationships between larval settlement and the timing and extended duration of coral spawning events in Kenya. In contrast to coral settlement in most other tropical regions, Pocilloporidae dominated on settlement tiles and comprised 93.7% of spat, while Acroporidae, Poritidae and Faviidae comprised 4.7% of spat. Coral settlement varied significantly spatially and temporally, with space-time interactions occurring. Annual mean spat densities in the park (101 spat m -2 ) were comparable to data from sub- tropical reefs, while densities in the reserve (908 spat m -2 ) were comparable to tropical reefs. These data suggest that there is no distinct latitudinal gradient in spat density along the East African coast. Spat settlement was seasonal, with peak settlement occurring predominantly on tiles immersed from February to May during the northeast monsoon, and was consistent with the timing of gamete release in Acropora and faviid species in Kenya. While non-coral fauna was 4 times more abundant than corals on settlement tiles, there was no evidence of significant competition among these spat groups. It is suggested that the relatively asynchronous and extended breeding season in Kenyan corals may result in reduced competition during settlement.

Settlement and early survival of red coral on artificial substrates in different geographic areas: some clues for demography and restoration

Settlement and early survival of red coral on artificial substrates in different geographic areas: some clues for demography and restoration

Opportunistic responses of Diadema antillarum (Echinodermata: Echinoidea) populations following the 1997–98 El Niño event in Bahia, Brazil

We present results from a seven year (1995–2001) study on the coral reefs in Bahia (Brazil), the reef invertebrate community being severely impacted by the 1997–98 El Niño Southern Oscillation event. Despite local extinction of some taxa, the urchin Diadema antillarum was the only species out of a total of 678 enumerated demonstrating a significant increase in population size following El Niño, indicating a unique response of this species to the stresses associated with these events. Other species of echinoid did not show such a response, most disappearing from the fauna during the two post-El Niño years. The increasing Diadema numbers were most likely due to movement of individuals onto the reef systems from deeper water, exploiting the conditions on the reefs caused by a reduction in competitors and, we speculate, an increase in available space on the reef allowing potential algal settlement to sustain this elevated urchin population. This increased grazing pressure may have prevented algae covering the reef, as seen in other Atlantic reef systems, allowing new coral settlement in 2001.

Effects of artificial settlement plate materials and methods of deployment on the sessile epibenthic community development in a tropical environment

The choice of substrata and the methods of deployment in analyses of settlement in benthic communities are often driven by the cost of materials and their local availability, and comparisons are often made between studies using different methodologies. The effects of varying artificial substratum, size of replicates and method of deployment were determined on a shallow reef in Eilat, Israel, while the effect of size of replicates was also investigated on a shallow reef in Sharm El Sheikh, Egypt. When statistical power was high enough, that is, when sufficient numbers of settlers were recorded, significant differences were found between materials used, tile size and methods of deployment. Significant differences were detected in total coral settlement rates and for the two dominant taxonomic groups, acroporids and pocilloporids. Standardisation of tile materials, dimensions, and method of deployment is needed for comparison between coral and other epibiont settlement studies. However, a greater understanding of the effects of these experimental variables on settlement processes may enable retrospective comparisons between studies utilising a range of materials and methods.

Influence of dead coral substrate morphology on patterns of juvenile coral distribution

This study examines the abundances of three morphological categories of juvenile corals (massive, branching and encrusting) on two different types of natural substratum, dead massive and dead branching corals. The overall results show that the morphological characteristics of dead coral substratum have a significant influence on the coral recruitment patterns with respect to the morphology of the recruits: juvenile corals of massive and branching types were more abundant on substrates of corresponding morphology. The results obtained from this study suggest that dead coral might attract coral larvae that are morphologically similar. On the other hand, it may be the result of post-settlement mortality. Whatever the mechanism shaping the patterns is, it seems that the physical morphology of the dead coral substrate has a significant influence on the coral recruit assemblage. Hence, we suggest that substrate morphology can be an important qualitative factor for coral settlement and a possible determinant of community structure.

Coral settlement onto Halimeda opuntia: a fatal attraction to an ephemeral substrate?

Degraded reefs with a high abundance of macroalgae usually also have low densities of coral recruits. Few studies, however, have examined whether these algae affect coral larval settlement. This study demonstrates, experimentally, that larvae of the Caribbean coral Favia fragrum can settle on the green alga Halimeda opuntia even when another substrate more suitable for settlement is present. Larval settlement onto experimental substrates was quantified under three treatments: rubble only, rubble plus plastic algal mimic, and rubble plus live H. opuntia. Similar total larval settlement was observed in all treatments. No larvae settled on the algal mimic, but total settlement was similar on the rubble in the first two treatments, showing that the rubble alone offered sufficient substrate for high settlement success. About half the larvae in the live algal treatment settled on H. opuntia instead of on the rubble, showing that larvae did not reject this substrate as they did the algal mimic. This result raises the possibility that corals will settle on some macroalgae when their abundance is high. Most macroalgae, including H. opuntia, are ephemeral substrates unsuitable for post-settlement survival. Such unexpected settlement may therefore have significant consequences for coral recruitment success on algal-dominated reefs.

Floating and fixed artificial habitats: effects of substratum motion on benthic communities in a coral reef environment

Despite the proliferation in coastal development world-wide little is known of the biological and ecological effects of man-made submerged habitats in coastal reefal environments. Such habitats, when able to move, offer unique environmental conditions, mainly in terms of hydro- dynamic aspects. The current study tested whether floating habitats would develop unique commu- nities in comparison to identical fixed ones, due to differences in current regime between the 2 types of habitat. We found significant differences in the hydrodynamic features associated with habitats of different motion capabilities, predominantly in mass-transfer rate, current velocity and shear stress. Floating installations had greater flow velocities and shear stress compared to fixed ones. We suggest that these hydrodynamic features determine the nature of the benthic communities on floating and fixed habitats, as the former revealed greater biomass and less chlorophyll content compared to the latter, while coral settlement was greater on the fixed installations, particularly near the seabed. The motion of floating artificial habitats increased the mass-transfer rate, as reflected by higher current velocities, and elevated the shear stress felt on their surfaces. These conditions encourage massive settlement of benthic macroinvertebrates and determine the community structure of floating artificial habitats in reefal environments.

Effects of monsoon-driven wave action on coral reefs of Guam and implications for coral recruitment

Benthic cyanobacteria can respond rapidly to favorable environmental conditions, overgrow a variety of reef organisms, and dominate benthic marine communities; however, little is known about the dynamics and consequences of such cyanobacterial blooms in coral reef ecosystems. In this study, the benthic community was quantified at the time of coral spawnings in Guam to assess the substrate that coral larvae would encounter when attempting settlement. Transects at 9, 18, and 25-m depths were surveyed at two reef sites before and after heavy wave action driven by westerly monsoon winds. Communities differed significantly between sites and depths, but major changes in benthic community structure were associated with wave action driven by monsoon winds. A shift from cyanobacteria to crustose coralline algae (CCA) accounted for 44% of this change. Coral recruitment on Guam may be limited by substrate availability if cyanobacteria cover large areas of the reef at the time of settlement, and consequently recruitment may in part depend upon wave action from annual monsoon winds and tropical storms which remove cyanobacteria, thereby exposing underlying CCA and other substrate suitable for coral settlement.

Permanent ‘phase shifts’ or reversible declines in coral cover? Lack of recovery of two coral reefs inSt. John, US Virgin Islands

Caribbean coral reefs have changed dramatically in the last 3 to 4 decades, with significant loss of coral cover and increases in algae. Here we present trends in benthic cover from 1989 to 2003 at 2 reefs (Lameshur Reef and Newfound Reef) off St. John, US Virgin Islands (USVI). Coral cover has declined in the fore-reef zones at both sites, and no recovery is evident. At Lameshur Reef, Hurricane Hugo (1989) caused significant physical damage and loss of coral. We suggest that macroalgae rapidly colonized new substrate made available by this storm and have hindered or prevented growth of adult corals, as well as settlement and survival of new coral recruits. Overfishing of herbivorous fishes in the USVI and loss of shelter for these fishes because of major storms has presumably reduced the levels of herbivory that formerly controlled algal abundance. Coral cover declined at Newfound Reef from 1999 to 2000, most likely because of coral diseases. The trends that we have documented, loss of coral followed by no evidence of recovery, appear similar to findings from other studies in the Caribbean. We need to focus on functional shifts in the resilience of coral reefs that result in their inability to recover from natural and human-caused stressors.

Invasibility: the local mechanism driving community assembly and species diversity

Recent theoretical developments involving community assembly on the one hand, and invasion biology on the other, suggest a gradual convergence in thought between what have been two largely separate theoretical initiatives. The term ‘‘invasibility’’ emerged in the field of invasion ecology to describe the susceptibility of environments to invasion by species from other regions of the world. Although Elton did not use the term ‘‘invasibility’’ in his pioneering book (1958), he did employ the concept, referring to an ecosystem’s ‘‘vulnerability to invasion’’. Given its original definition, the concept of invasibility has been limited in its scope and use, with rather little application to the larger field of community ecology. However, our assessment and usage of the concept (Davis et al. 2000, 2001) has prompted us to consider invasibility as a more general condition of all environments. This expanded perspective of invasibility has caused us to reconsider some fundamental questions and issues regarding community assembly and species diversity as well as recent discussions involving the notion of metacommunities (Leibold and Miller 2004, Leibold et al. 2004). By metacommunity, we mean a set of local communities that are linked by dispersal of multiple, and potentially interacting, species (Leibold et al. 2004). Recent theoretical efforts to characterize community assembly processes have reemphasized understanding the importance of interactions between local and regional processes (Levine 2000, Hubbell 2001, Tilman 2004, Foster and Dickson 2004, Jiang and Morin 2004, Steiner and Leibold 2004, Leibold et al. 2004). There is general agreement that the diversity of the regional species pool and the extent of dispersal of the species from this pool throughout the region are the principal regional processes involved. However, investigators have emphasized the importance of different local conditions and processes, including productivity (Jiang and Morin 2004, Steiner and Leibold 2004), demographic stochasticity (Tilman 2004), ecosystem size (Fukami 2004), biotic limitation of diversity (Tilman 2004), and even extent of tree lean, the latter which affects colonization success of epiphyes (Snall et al. 2005). We propose that the notion of invasibility can serve as a unifying concept in these discussions and thereby can facilitate current efforts to develop a more comprehensive and realistic theory of community assembly and metacommunity dynamics.

Evidence of the role of Diadema antillarum in the promotion of coral settlement and survivorship

Evidence of the role of Diadema antillarum in the promotion of coral settlement and survivorship

History of Indo-Pacific coral reef systems since the last glaciation: Development patterns and controlling factors

History of Indo-Pacific coral reef systems since the last glaciation: Development patterns and controlling factors