scholarly journals Increased Coral Larval Supply Enhances Recruitment for Coral and Fish Habitat Restoration

2021 ◽  
Vol 8 ◽  
Author(s):  
Peter L. Harrison ◽  
Dexter W. dela Cruz ◽  
Kerry A. Cameron ◽  
Patrick C. Cabaitan
Keyword(s):  
Colony Size ◽  
Larval Settlement ◽  
Fish Abundance ◽  
Larval Rearing ◽  
Total Production ◽  
Larval Supply ◽  
Coral Recruitment ◽  
Fine Mesh ◽  
Mean Diameter

Loss of foundation reef-corals is eroding the viability of reef communities and ecosystem function in many regions globally. Coral populations are naturally resilient but when breeding corals decline, larval supply becomes limiting and natural recruitment is insufficient for maintaining or restoring depleted populations. Passive management approaches are important but in some regions they are proving inadequate for protecting reefs, therefore active additional intervention and effective coral restoration techniques are needed. Coral spawning events produce trillions of embryos that can be used for mass larval rearing and settlement on degraded but recoverable reef areas. We supplied 4.6 million Acropora tenuis larvae contained in fine mesh enclosures in situ on three degraded reef plots in the northwestern Philippines during a five day settlement period to initiate restoration. Initial mean larval settlement was very high (210.2 ± 86.4 spat per tile) on natural coral skeleton settlement tiles in the larval-enhanced plots, whereas no larvae settled on tiles in control plots. High mortality occurred during early post-settlement life stages as expected, however, juvenile coral survivorship stabilised once colonies had grown into visible-sized recruits on the reef by 10 months. Most recruits survived and grew rapidly, resulting in significantly increased rates of coral recruitment and density in larval-enhanced plots. After two years growth, mean colony size reached 11.1 ± 0.61 cm mean diameter, and colonies larger than 13 cm mean diameter were gravid and spawned, the fastest growth to reproductive size recorded for broadcast spawning corals. After three years, mean colony size reached 17 ± 1.7 cm mean diameter, with a mean density of 5.7 ± 1.25 colonies per m–2, and most colonies were sexually reproductive. Coral cover increased significantly in larval plots compared with control plots, primarily from A. tenuis recruitment and growth. Total production cost for each of the 220 colonies within the restored breeding population after three years was United States $17.80 per colony. A small but significant increase in fish abundance occurred in larval plots in 2018, with higher abundance of pomacentrids and corallivore chaetodontids coinciding with growth of A. tenuis colonies. In addition, innovative techniques for capturing coral spawn slicks and larval culture in pools in situ were successfully developed that can be scaled-up for mass production of larvae on reefs in future. These results confirm that enhancing larval supply significantly increases settlement and coral recruitment on reefs, enabling rapid re-establishment of breeding coral populations and enhancing fish abundance, even on degraded reef areas.

scholarly journals Soundscapes influence the settlement of the common Caribbean coral Porites astreoides irrespective of light conditions

2018 ◽  
Vol 5 (12) ◽  
pp. 181358 ◽  
Author(s):  
Ashlee Lillis ◽  
Amy Apprill ◽  
Justin J. Suca ◽  
Cynthia Becker ◽  
Joel K. Llopiz ◽  
...  
Keyword(s):  
Larval Settlement ◽  
Low Frequency ◽  
Fish Abundance ◽  
Light Conditions ◽  
Coral Larvae ◽  
Acoustic Environment ◽  
Porites Astreoides ◽  
Caribbean Coral ◽  
The Common

The settlement of reef-building corals is critical to the survival and recovery of reefs. Recent evidence indicates that coral larvae orient towards reef sound, yet the components of the acoustic environment that may attract coral larvae and induce settlement are unknown. Here we investigated the effects of ambient soundscapes on settlement of Porites astreoides coral larvae using in situ chambers on reefs differing in habitat quality (coral and fish abundance). Mean larval settlement was twice as high in an acoustic environment with high levels of low-frequency sounds, typical of a high-quality, healthy reef; this result was observed in both natural light and dark treatments. Overall, the enhancement of coral settlement by soundscapes typical of healthy reefs suggests a positive feedback where soundscape properties of reefs with elevated coral and fish abundance may facilitate coral recruitment.

scholarly journals Effect of incubation time and substrate concentration on N-uptake rates by phytoplankton in the Bay of Bengal

2005 ◽  
Vol 2 (5) ◽  
pp. 1331-1352
Author(s):  
S. Kumar ◽  
R. Ramesh ◽  
S. Sardesai ◽  
M. S. Sheshshayee
Keyword(s):  
Incubation Time ◽  
Uptake Rate ◽  
Nitrate Uptake ◽  
N Uptake ◽  
Marine Phytoplankton ◽  
Total Production ◽  
New Production ◽  
Urea Uptake ◽  
Uptake Rates

Abstract. We report here the results of three experiments, which are slight variations of the 15N method (JGOFS protocol) for determination of new production. The first two test the effect of (i) duration of incubation time and (ii) concentration of tracer added on the uptake rates of various N-species (nitrate, ammonium and urea) by marine phytoplankton; while the third compares in situ and deck incubations from dawn to dusk. Results indicate that nitrate uptake can be underestimated by experiments where incubation times shorter than 4h or when more than 10% of the ambient concentration of nitrate is added prior to incubation. The f-ratio increases from 0.28 to 0.42 when the incubation time increases from two to four hours. This may be due to the observed increase in the uptake rate of nitrate and decrease in the urea uptake rate. Unlike ammonium [y{=}2.07x{-}0.002\\, (r2=0.55)] and urea uptakes [y{=}1.88x{+}0.004 (r2=0.88)], the nitrate uptake decreases as the concentration of the substrate (x) increases, showing a negative correlation [y{=}-0.76x+0.05 (r2=0.86)], possibly due to production of glutamine, which might suppress nitrate uptake. This leads to decline in the f-ratio from 0.47 to 0.10, when concentration of tracer varies from 0.01 to 0.04μ M. The column integrated total productions are 519 mg C m-2 d-1 and 251 mg C m-2 d-1 for in situ and deck incubations, respectively. The 14C based production at the same location is ~200 mg C m-2 d-1, which is in closer agreement to the 15N based total production measured by deck incubation.

scholarly journals The gas production of 14 species from comet 67P/Churyumov–Gerasimenko based on DFMS/COPS data from 2014 to 2016

2020 ◽  
Vol 498 (3) ◽  
pp. 3995-4004 ◽  
Author(s):  
Matthias Läuter ◽  
Tobias Kramer ◽  
Martin Rubin ◽  
Kathrin Altwegg
Keyword(s):  
Error Bounds ◽  
Temporal Evolution ◽  
Gas Production ◽  
Total Production ◽  
Time Intervals ◽  
Triangular Elements ◽  
Double Focusing ◽  
Comet 67P ◽  
Northern And Southern Hemispheres

ABSTRACT The coma of comet 67P/Churyumov–Gerasimenko has been probed by the Rosetta spacecraft and shows a variety of different molecules. The ROSINA COmet Pressure Sensor and the Double Focusing Mass Spectrometer provide in situ densities for many volatile compounds including the 14 gas species H2O, CO2, CO, H2S, O2, C2H6, CH3OH, H2CO, CH4, NH3, HCN, C2H5OH, OCS, and CS2. We fit the observed densities during the entire comet mission between 2014 August and 2016 September to an inverse coma model. We retrieve surface emissions on a cometary shape with 3996 triangular elements for 50 separated time intervals. For each gas, we derive systematic error bounds and report the temporal evolution of the production, peak production, and the time-integrated total production. We discuss the production for the two lobes of the nucleus and for the Northern and Southern hemispheres. Moreover, we provide a comparison of the gas production with the seasonal illumination.

Year-class detection reveals climatic modulation of settlement strength in the European lobster, Homarus gammarus

2002 ◽  
Vol 59 (7) ◽  
pp. 1132-1143 ◽  
Author(s):  
M R.J Sheehy ◽  
R C.A Bannister
Keyword(s):  
Stock Assessment ◽  
Global Climate ◽  
Larval Settlement ◽  
European Lobster ◽  
Homarus Gammarus ◽  
Cross Correlation Analysis ◽  
Age Dependent ◽  
Intractable Problem ◽  
First Time

Understanding the nature of recruitment relationships in the European lobster, Homarus gammarus, has been an intractable problem because of difficulties associated with quantification of its scarce planktonic larvae and early benthic phase. We attempt to address this problem by analyzing the age composition of a population off the northeast coast of England. Age-dependent in situ deposits of neurolipofuscin in the eyestalk are used as an age index. An approach is presented that accounts and (or) corrects for the two most important potential sources of error in age determinations by this technique, namely environmental temperature variation and unexplained individual variation. This yields, for the first time in very long-lived clawed lobsters, reproducible catch age structures with year-class resolution. The method should be generally applicable to crustaceans. Cross-correlation analysis shows that larval settlement strength in the European lobster is associated with local sea temperatures and onshore winds in a manner similar to that reported for other lobsters. These findings have important implications for stock assessment, particularly the use of traditional models dependent on size and steady state, yield forecasting, the effects of global climate change, arguments about spawner protection or restocking, and the spawner–recruit relationship.

Morphologic Modification in ABS by the Incorporation “in Situ” of Nano-ZnO: Study of the Effect on Characteristics and Final Properties

2010 ◽  
Vol 644 ◽  
pp. 135-138 ◽  
Author(s):  
Ramón Díaz de León ◽  
Rebeca Betancourt-Galindo ◽  
Bertha A. Puente Urbina ◽  
Pablo Acuña ◽  
Luís Falcón
Keyword(s):  
Acrylonitrile Butadiene Styrene ◽  
Total Production ◽  
X Ray Diffraction ◽  
Nano Zno ◽  
Suspension Process ◽  
Styrene Acrylonitrile ◽  
Poly Acrylonitrile ◽  
Period Of Occurrence ◽  
Molecular Weight Increase

The synthesis of poly(acrylonitrile-butadiene-styrene) (ABS) was carried out using the mass-suspension process, high cis polybutadiene (PB), benzoyl peroxide (BPO) as the initiator and modified and unmodified nanoparticles of zinc oxide (nano-ZnO). X-ray diffraction (XRD) and Fourier transform infrared (FTIR) were used to characterize the ZnO nanoparticles. A Universal tensiometer, Brokfield viscosimeter and transmission electronic microscopy (TEM) were used to characterize ABS. The employment of nano-ZnO induced an impressive morphologic modification and transformed the highly occluded salame morphology of poly(styrene-acrylonitrile) (SAN) to a highly dispersed one in its matrix. During the reaction, a decrease in the total production of SAN was observed due to the interaction between radicals produced by the initiator and nano-ZnO, causing a molecular weight increase of SAN. The nano-ZnO also induced a decline in the phase inversion and extended the period of occurrence. ABS without nano-ZnO yielded higher mechanical properties than one without any nanoparticles.

scholarly journals Ultrastructural and molecular characteristics of crayfish photoreceptor membranes.

1976 ◽  
Vol 69 (3) ◽  
pp. 721-732 ◽  
Author(s):  
H R Fernandez ◽  
E E Nickel
Keyword(s):  
Freeze Fracture ◽  
Photoreceptor Cells ◽  
Molecular Characteristics ◽  
Thin Sections ◽  
Freeze Fracturing ◽  
Mean Diameter ◽  
Hexagonal Arrangement ◽  
Photoreceptor Membranes

The ultrastructure of photoreceptor cells of the crayfish (P. clarkii) has been examined by means of thin sections and freeze-fracturing. The study reveals that in the photoreceptor membranes there are particles associated primarily with the A faces of freeze-fracture preparations which have a mean diameter of 80-84 A and a density of 6,600 per per micrometer2. Treatment of the retina with digitonin (a substance capable of extracting visual photopigments) in Ringer's causes marked disruption of the hexagonal arrangement of the microvilli, breakdown of the microvilli into smaller segments, and gradual removal of the particles. The estimated photopigment concentration in the microvillus is 4,000 per micrometer. It is suggested that the observed particles represent the photopigment in situ.

Electron Microscopy of Ion Deposited Thin Films of the Oxides of Titanium

1985 ◽  
Vol 62 ◽  
Author(s):  
A. B. Harker ◽  
D. G. Howitt ◽  
P. J. Hood ◽  
P. Kobrin
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Ion Beam ◽  
Phase 1 ◽  
Equilibrium Phase ◽  
Free Standing ◽  
Fine Mesh ◽  
Voltage Electron ◽  
Post Deposition

ABSTRACTThe reactive ion beam deposition of ceramic films onto unheated substrates can produce amorphous films with essentially molecular mixing. The annealing and hot isotatic pressing (hipping) of these films to produce crystalline phases have reproducable effects which are sensitive to the temperature and the density of the film. Experiments with titanium oxides indicate that it is principally the equilibrium phases that are formed and that hipping can be used to encourage the same transformations at lower temperatures.Thin films of titanium oxide close to the stoichiometry of TiO2 were deposited onto unheated substrates of sodium chloride. Some of the films were removed from the substrate by floating them off in water and the remainder were either annealed or hipped to induce crystallization. The anneals were performed either in air or argon and the hipping was done under an argon pressure of about twenty thousand pounds per square inch. Several of the free standing films were annealed in the same atmospheres on nickel grids. All the specimens were prepared for transmission electron microscopy by the same floating technique and were examined in a Philips 400 T.E.M. at 125 keV. The as deposited films were amorphous and showed no visible texture other than that derived from a small amount of porosity. The films were sufficiently conductive that they could be examined directly in the T.E.M. without carbon coating provided they were supported on a grid of fairly fine mesh. One specimen was also examined in the Kratos 1.5 MeV high voltage electron microscope at the National Center for Electron Microscopy. The specimen was annealed in vacuum using an in-situ hot stage to directly observe the behavior of the film.The post deposition annealing and hipping of these films reproducibly induced the crystallization of anatase below 800°C. This is the equilibrium phase [1] and the extent to which the films transformed and the morphology of the growing crystallites were determined principally by the film thickness. There was little difference between the responses of free standing films and films left on the salt substrate. They tended to transform at about the same temperature, which was reproduced in the in-situ hot stage experiment and the microsructures which formed were very similar. The dependence upon thickness was also reflected in all the microstructures of the different post deposition treatments and it was possible to complete the transformations that were very sluggish in some of the films by hipping them at the same temperatures.

Local-scale Patterns of Larval Settlement in a Planktivorous Damselfish—Do They Predict Recruitment?

1996 ◽  
Vol 47 (2) ◽  
pp. 449 ◽  
Author(s):  
RJ Schmitt ◽  
SJ Holbrook
Keyword(s):  
Spatial Variation ◽  
Larval Settlement ◽  
French Polynesia ◽  
Local Scale ◽  
Larval Supply ◽  
Sea Anemones ◽  
Spatial Variance ◽  
Immigration And Emigration ◽  
Per Capita ◽  
Free Ranging

The degree to which local-scale spatial variation in larval supply predicted subsequent patterns in juvenile densities was examined for a planktivorous damselfish (Dascyllus trimaculatus) at Moorea, French Polynesia. D. trimaculatus young settle from the plankton to sea anemones, where they remain until becoming free-ranging adults. Daily settlement onto anemones without fish was estimated at several sites in a lagoon for one 14-day period and compared with patterns in the density of juveniles that had accrued after 10 successive settlement periods. Spatial variation attributable to larval supply occurred mostly among individual anemones, between the halves of each study site, and among different locations in the lagoon. In contrast, there was relatively little variation at any spatial scale in the density of young after 10 settlement pulses. Several mechanisms were examined that could account for the observed reduction in spatial variance through time, and three involving interactions with young already present were implicated. First, settlement was not independent of residents (the density of young already on an anemone); compared with the absence of fish, settlement was facilitated at low and inhibited at high densities of residents. Second, older juveniles moved among local anemones, and the immigration and emigration rates per capita varied with density on an anemone. Finally, per capita mortality during the first few days after settlement was density-dependent. These findings emphasize the critical need to distinguish among effects that arise from the delivery of larvae, the availability of appropriate habitat, and interactions that affect fish at settlement and immediately thereafter.

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