Débora O. Pires

Sexual reproduction of Brazilian coral Mussismilia hispida (Verrill, 1902)

Abstract. Using histological analysis, the reproductive pattern of Mussismilia hispida, a zooxanthellate coral species endemic to the Brazilian coast, was verified. Fragments from two tagged colonies and ten haphazardly chosen colonies were collected monthly, from April 1989 to March 1990, at Praia da Tartaruga, Buzios, Rio de Janeiro state. The results showed that M. hispida is a sequential hermaphroditic species with a broadcast-spawning mode of reproduction. Small immature oocytes were first observed in April 1989 while early spermatic cysts were found in December 1989. After entering the mesoglea, the largest oocytes increase in size by incorporating the smallest ones into their cytoplasm. Mature oocytes and spermaries occurred concomitantly on the same fertile mesenteries during summer, and disappeared from some samples between February 1990 and March 1990 (late summer/early autumn). Gonad maturation occurred with increasing seawater temperature, suggesting seasonal synchrony in the reproductive cycle. Not all oocytes reached their full development, and some were resorbed after a short period of degeneration. No zooxanthellae were found in pre-spawn oocytes, which characteristically had a large amount of vitelline material and a peripheral germ vesicle.

Colony size-frequency distributions among different populations of the scleractinan coral Siderastrea stellata in Southwestern Atlantic: implications for life history patterns

Colony size-frequency distributions of reef corals may be used to infer growth potential and population responses upon environmental changes. The present paper compares the size structure of colonies of Siderastrea stellata Verrill, 1868,among 11 sites, six of them distributed along a gradient of sediment deposition in Abrolhos, Bahia, Brazil (18o S). Results indicated that the population structure is likely to be influenced by local conditions, rather than large scale factors, such as latitude. The 11 distributions, however, showed higher frequencies of small size classes. Class 1 (up to 2.5 cm diameter) was always present and the frequency of colonies from size class 3 (10 cm diameter) tended to decrease in all sites. Comparison among the six Abrolhos sites showed that S. stellata has advantages at sites with intermediate sedimentation, where colonies attain larger sizes, probably, reflecting a higher survivorship over time. The present study showed that, despite the influence of environmental conditions on parameters of the populations such as size of colony, the life history strategy of S. stellata reflects a local adaptation that allows its development and survivorship in shallow waters and horizontal substrates, sites characterized by high mortality rates.

Identification of a Novel Antimicrobial Peptide from Brazilian Coast Coral Phyllogorgia dilatata

The marine ecosystem is able to provide enormous biomolecule diversity that could be used for treatment of various diseases. In this highly competitive environment, organisms need chemical barriers to reduce or avoid microorganism contamination. Among the molecules that protect these animals the antimicrobial peptides (AMPs) are included. In the present study, crude extracts of coral coral specimens Carijoa riisei, Muriceopsis sulphurea, Neospongodes atlantica, Palythoa caribeorum, Phyllogorgia dilatata and Plexaurella grandiflora were challenged against multiple Grampositive and -negative bacteria showing different activities. P. dilatata crude extract showed the antibacterial activity, and was ammonium-sulfate (0-40%) fractionated, being able to control the growth of K. pneumoniae, S. flexineri and S. aureus. Rich-fraction was further purified by using Amicon® Ultra Centrifugal 10 kDa associated with reversed-phase HPLC chromatography (C18), producing the peptide named Pd-AMP1. Pd-AMP1 was able to inhibit S. aureus development. Mass spectrometry analyses showed a monoisotopic mass of 5372.66 Da and N-terminal sequence showed no significant match with databank. In this view, the prospecting of protein biomolecules and biotechnological potential from marine animals is still little explored and may serve as an alternative to common antibiotics.

Comparison of different protocols for the extraction of microbial DNA from reef corals

This study aimed to test different protocols for the extraction of microbial DNA from the coral Mussismilia harttii. Four different commercial kits were tested, three of them based on methods for DNA extraction from soil (FastDNA SPIN Kit for soil, MP Bio, PowerSoil DNA Isolation Kit, MoBio, and ZR Soil Microbe DNA Kit, Zymo Research) and one kit for DNA extraction from plants (UltraClean Plant DNA Isolation Kit, MoBio). Five polyps of the same colony of M. harttii were macerated and aliquots were submitted to DNA extraction by the different kits. After extraction, the DNA was quantified and PCR-DGGE was used to study the molecular fingerprint of Bacteria and Eukarya. Among the four kits tested, the ZR Soil Microbe DNA Kit was the most efficient with respect to the amount of DNA extracted, yielding about three times more DNA than the other kits. Also, we observed a higher number and intensities of DGGE bands for both Bacteria and Eukarya with the same kit. Considering these results, we suggested that the ZR Soil Microbe DNA Kit is the best adapted for the study of the microbial communities of corals.

Broadcast Spawning Coral Mussismilia hispida Can Vertically Transfer its Associated Bacterial Core

The hologenome theory of evolution (HTE), which is under fierce debate, presupposes that parts of the microbiome are transmitted from one generation to the next [vertical transmission (VT)], which may also influence the evolution of the holobiont. Even though bacteria have previously been described in early life stages of corals, these early life stages (larvae) could have been inoculated in the water and not inside the parental colony (through gametes) carrying the parental microbiome. How Symbiodinium is transmitted to offspring is also not clear, as only one study has described this mechanism in spawners. All other studies refer to incubators. To explore the VT hypothesis and the key components being transferred, colonies of the broadcast spawner species Mussismilia hispida were kept in nurseries until spawning. Gamete bundles, larvae and adult corals were analyzed to identify their associated microbiota with respect to composition and location. Symbiodinium and bacteria were detected by sequencing in gametes and coral planula larvae. However, no cells were detected using microscopy at the gamete stage, which could be related to the absence of those cells inside the oocytes/dispersed in the mucus or to a low resolution of our approach. A preliminary survey of Symbiodinium diversity indicated that parental colonies harbored Symbiodinium clades B, C and G, whereas only clade B was found in oocytes and planula larvae [5 days after fertilization (a.f.)]. The core bacterial populations found in the bundles, planula larvae and parental colonies were identified as members of the genera Burkholderia, Pseudomonas, Acinetobacter, Ralstonia, Inquilinus and Bacillus, suggesting that these populations could be vertically transferred through the mucus. The collective data suggest that spawner corals, such as M. hispida, can transmit Symbiodinium cells and the bacterial core to their offspring by a coral gamete (and that this gamete, with its bacterial load, is released into the water), supporting the HTE. However, more data are required to indicate the stability of the transmitted populations to indicate whether the holobiont can be considered a unit of natural selection or a symbiotic assemblage of independently evolving organisms.

Comparison of the reproductive status of the scleractinian coral Siderastrea stellata throughout a gradient of 20º of latitude

Most studies on sexual reproduction of scleractinian corals in Brazil have been concentrated in a single population or in a small area (Pires et al., 1999; Francini et al., 2002; Neves & Pires, 2002; Pires & Caparelli, 2002; Pires et al., 2002; Lins-de-Barros et al., 2003). The present paper presents a comparison of the sexual reproductive status of six populations of the Brazilian scleractinian coral Siderastrea stellata Verrill, 1868. The six studied sites are distributed along a gradient of latitude of 20 in the Southwestern Tropical Atlantic Ocean, comprising areas throughout almost the whole species geographical distribution (Fig. 1).

First record of a reef coral spawning event in the western South Atlantic

Summary The first record of coral spawning in the South Atlantic was observed among Mussismilia hispida colonies at the “Laje de Santos” (24°19′ S, 046°11′ W). Several colonies were observed spawning for about 15 min, early on the night of April 29, 2000. Some colonies did not spawn and no colonies were observed spawning later than circa 20:00 h. The report of M. hispida spawning in Santos came from the southernmost area of occurrence of this species. Data from this record are compared with those from previous studies on the reproduction of this species.

Aspects of the life history of Siderastrea stellata in the tropical Western Atlantic, Brazil

Summary This paper presents the first study of the life history of a Brazilian reef coral, with reference to Siderastrea stellata. Fecundity and growth rate were determined for four colony size classes collected from the Itacolomis Reefs, Brazil (16°53.816′S; 039° 04.965′W). Colony size-frequency distribution was analyzed to evaluate the potential for maintenance, growth and recovery of the population. The fecundity of size class 1 (up to 2.5 cm in diameter or 5 cm2) was significantly lower than that of the other three classes, which did not differ among themselves (averaging 8 oocytes/polyp). Colonies with less than 1.8 cm in diameter (or 2.5 cm2) did not have gametes. The number of mature polyps tended to increase with colony size: some polyps of class 2 (2.5 < x ≤7.9 cm diameter) colonies did not have oocytes, while polyps from classes 3 (7.9 < x ≤ 12.6 cm diameter) and 4 (× >12.6 cm diameter) were always fertile. The linear extension was similar among the four size classes, being around 2.5 mm per year, corresponding to an annual increase of 5 mm in colony diameter. The first gametes occurred in the third year, with planulation occurring during the fourth year of life. Colony size-frequency distribution showed the presence of many size classes, as would be expected on undisturbed reefs. Class 2 colonies were the most abundant; the largest colony was 486 cm2 (or 25cm diameter), i.e. possibly 50 years old. Ten percent of colonies were within size class 1 (recruits) and 90% were sexually mature. The early onset of reproduction, brooding of larvae, intermediate size (average colony size at the studied site was 62 cm2, or 9 cm diameter), and massive corallum may be advantageous in the habitat preferentially occupied by S. stellata, namely, the reef top and horizontal substrates in shallow waters <10 m deep. The presence of large colonies, characterized by lower mortality rate, larger reproductive output and greater longevity, also indicates a low probability of population extinction. Disturbances that decrease colony sizes to less than 20 cm2 (or 5 cm in diameter), corresponding to a 10 years old colony, may sharply reduce the populations prospects of survival, since below this size, maximum fecundity has yet to be attained.

Production of three symbiosis-related fatty acids by Symbiodinium types in clades A–F associated with marine invertebrate larvae

Symbiodinium are dinoflagellates engaged in a mutualistic symbiosis with multiple coral reef taxa. They are divided in nine different clades (A–I), which typically associate with different hosts. However, very little information is available on metabolic differences in Symbiodinium types, especially when associated with metazoan larvae. We tested whether three ω3 fatty acids (stearidonic acid, SDA; docosapentaenoic acid, DPA; and docosahexaenoic acid, DHA) that are typically translocated from Symbiodinium to its host are produced by Symbiodinium types within clades A–F associated with Mussismilia hispida (scleractinian coral), Berghia stephanieae (nudibranch), and Tridacna crocea (giant clam) larvae. We acquired and spawned broodstock for each host, cultured their larvae, and offered Symbiodinium types belonging to clades A–F. Samples were taken during a 72-h window after the offer of Symbiodinium, and fatty acids were extracted and analyzed by gas chromatography. The concentrations of SDA and DPA for all host larvae–dinoflagellate associations were low and variable, without trends. However, M. hispida planula larvae associated with Symbiodinium A1 and C1 had a statistically significant higher amount of DHA. The veliger larvae of B. stephanieae digested the Symbiodinium, and the amount of DHA remained constant throughout the experiment. The veliger larvae of T. crocea associated with Symbiodinium A1 and C1 also presented a higher amount of DHA, although not statistically different from the other types. These results show that Symbiodinium A1 and C1, in the case of M. hispida and T. crocea (which usually harbor strains within clades A and C), may contribute a small amount of DHA to the larvae of these organisms and form a stronger mutualism than other strains.

Cyanobacterial and microeukaryotic profiles of healthy, diseased, and dead Millepora alcicornis from the South Atlantic

Coral reefs are at risk due to events associated with human activities, which have resulted in the increasing occurrence of coral diseases. Corals live in symbiotic relationships with different microorganisms, such as cyanobacteria, a very important group. Members of the phylum Cyanobacteria are found in great abundance in the marine environment and may play an essential role in keeping corals healthy but may also be pathogenic. Furthermore, some studies are showing a rise in cyanobacterial abundance in coral reefs as a result of climate change. The current study aimed to improve our understanding of the relationship between cyanobacteria and coral health. Our results revealed that the cyanobacterial genus GPI (Anabaena) is a possible opportunistic pathogen of the coral species Millepora alcicornis in the South Atlantic Ocean. Furthermore, the bacterial and microeukaryotic profile of healthy, diseased, and post-disease (skeletal) regions of affected coral indicated that a microbial consortium composed of Anabaena sp., Prosthecochloris sp., and microeukaryotes could be involved in this pathogenicity or could be taking advantage of the diseased state.