Bioaerosol assessment in the library of Istanbul University and fungal flora associated with paper deterioration

Health problems in people who are in indoor environments with poor ventilation have resulted in an increase in the number of studies regarding air quality. Microorganisms and inferior indoor air-climatic conditions not only affect human health but also cause decay of invaluable materials present in libraries. Therefore, this study aimed to assess the culturable bioaerosol composition and concentration in the library of Istanbul University. The culturable fungal flora, a biodeterioration agent, of the damaged archival materials was also examined. The air was sampled for a year, as were the surfaces of 207 biologically damaged books. The fungal colonies’ range was between 235 and 1850 CFU/m³, and the bacterial colonies range between 270 and 1920 CFU/m³. This is the first volumetric record in Turkey. Although the microbial contamination was not very high, molds such as Aspergillus versicolor, Cladosporium sphaerospermum, Penicillium chrysogenum, Alternaria alternata, Chaetomium globosum, Aspergillus flavus, and Aspergillus ochraceus might cause harm to human beings or to books as biodeterioration agents. The highest amount of fungus was determined in Archive 3, which contained damaged books. The fungal species isolated from the air and books were essentially the same. Therefore, it is important to determine not only the numeric values but also the microbiological composition of fungal colonies because the variety of fungal species is indicative of a deterioration process in effect over a long period. The deterioration of books must be remedied.     

Changes in the bacterial community and extracellular compounds associated with the disaggregation of Microcystis colonies

Microcystis is a well-studied type of bloom-forming genus cyanobacteria that occurs as colonies in lakes. However, whenever Microcystis colonies are transferred to the laboratory, they always disaggregate into a unicellular form. The mechanism underlying this disaggregation of Microcystis colonies remains uncharacterized. Here, we report on the changes in morphology and the changes in the composition of the associated bacterial community of Microcystis wesenbergii colonies. Denaturing gradient gel electrophoresis analysis (DGGE) showed that the diversity of the associated bacterial community decreased during the disaggregation of Microcystis colonies. Two γ-Proteobacteria and one Bacteroidetes species from the mucilage of Microcystis colonies were not detected following colony disaggregation, suggesting that these species may influence Microcystis colony morphology. Solid phase microextraction and gas chromatography–mass spectrometry (SPME GC/MS) analysis revealed that seven of the forty-one extracellular compounds detected were exclusively present in the media of the Microcystis colony extracts; these compounds may be secreted by bacteria and may be a beneficial role in Microcystis colony maintenance. The results of this study indicate that changes in the composition of the bacterial community associated with Microcystis colonies are likely responsible for the disaggregation of these colonies in the laboratory.     

Identification and characterization of potentially algal-lytic marine bacteria strongly associated with the toxic dinoflagellate Alexandrium catenella

The toxic dinoflagellate Alexandrium catenella isolated from fjords in Southern Chile produces several analogues of saxitoxin and has been associated with outbreaks of paralytic shellfish poisoning. Three bacterial strains, which remained in close association with this dinoflagellate in culture, were isolated by inoculating the dinoflagellate onto marine agar. The phenotypically different cultivable bacterial colonies were purified. Their genetic identification was done by polymerase chain reaction amplification of the 16S rRNA genes. Partial sequence analysis suggested that the most probable affiliations were to two bacterial phyla: Proteobacteria and the Cytophaga group. The molecular identification was complemented by morphological data and biochemical profiling. The three bacterial species, when grown separately from phytoplankton cells in high-nutrient media, released algal-lytic compounds together with aminopeptidase, lipase, glucosaminidase, and alkaline phosphatase. When the same bacteria, free of organic nutrients, were added back to the algal culture they displayed no detrimental effects on the dinoflagellate cells and recovered their symbiotic characteristics. This observation is consistent with phylogenetic analysis that reveals that these bacteria correspond to species distinct from other bacterial strains previously classified as algicidal bacteria. Thus, bacterial-derived lytic activities are expressed only in the presence of high-nutrient culture media and it is likely that in situ environmental conditions may modulate their expression.     

Developmental plasticity of bacterial colonies and consortia in germ-free and gnotobiotic settings

ABSTRACT: BACKGROUND: Bacteria grown on semi-solid media can build two types of multicellular structures, depending on the circumstances. Bodies (colonies) arise when a single clone is grown axenically (germ-free), whereas multispecies chimeric consortia contain monoclonal microcolonies of participants. Growth of an axenic colony, mutual interactions of colonies, and negotiation of the morphospace in consortial ecosystems are results of intricate regulatory and metabolic networks. Multicellular structures developed by Serratia sp. are characteristically shaped and colored, forming patterns that reflect their growth conditions (in particular medium composition and the presence of other bacteria). RESULTS: Building on our previous work, we developed a model system for studying ontogeny of multicellular bacterial structures formed by five Serratia sp. morphotypes of two species grown in either "germ-free" or "gnotobiotic" settings (i.e. in the presence of bacteria of other conspecific morphotype, other Serratia species, or E. coli). Monoclonal bodies show regular and reproducible macroscopic appearance of the colony, as well as microscopic pattern of its growing margin. Standard development can be modified in a characteristic and reproducible manner in close vicinity of other bacterial structures (or in the presence of their products). Encounters of colonies with neighbors of a different morphotype or species reveal relationships of dominance, cooperation, or submission; multiple interactions can be summarized in "rock -- paper -- scissors" network of interrelationships. Chimerical (mixed) plantings consisting of two morphotypes usually produced a "consortium" whose structure is consistent with the model derived from interaction patterns observed in colonies. CONCLUSIONS: Our results suggest that development of a bacterial colony can be considered analogous to embryogenesis in animals, plants, or fungi: to proceed, early stages require thorough insulation from the rest of the biosphere. Only later, the newly developing body gets connected to the ecological interactions in the biosphere. Mixed "anlagen" cannot accomplish the first, germ-free phase of development; hence, they will result in the consortium of small colonies. To map early development and subsequent interactions with the rest of the biospheric web, simplified gnotobiotic systems described here may turn to be of general use, complementing similar studies on developing multicellular eukaryots under germ-free or gnotobiotic conditions.     

Habitat use by Mountain Plovers in prairie dog colonies in northeastern New Mexico

ABSTRACT Mountain Plovers (Charadrius montanus) are grassland birds that often breed in close association with colonies of black‐tailed prairie dogs (Cynomys ludovicianus). However, not all colonies provide plover nesting habitat or habitat of equal quality, and the characteristics of colonies important for plovers remain poorly understood. Over two years, I used plover distribution surveys, territory mapping, and habitat sampling to study habitat use by plovers in prairie dog colonies in shortgrass prairie in northeastern New Mexico. My objective was to document important components of plover breeding habitat in colonies by comparing characteristics of used and unused habitats at three spatial scales: colony, territory, and nest‐site. I found evidence of plover breeding in 14 of 44 colonies in 2009 and 13 of 43 colonies in 2010. Based on logistic regression, the probability of a colony being occupied by plovers was positively associated with colony size, but negatively associated with mean vegetation height. Preference for larger colonies could relate to minimum habitat requirements, or a potential tendency of this species to nest in social clusters. Shorter vegetation height was strongly correlated with greater bare ground and lower forb/subshrub cover, all characteristics that may be related to plover predator avoidance and foraging microhabitat. At both the territory and nest‐site scale, areas used by plovers had shorter vegetation, more bare ground, and less forb/subshrub cover than unused areas. Nest sites were also more sloped, perhaps to reduce risk of flooding, and located further away from the nearest prairie dog burrow, perhaps to reduce risk of disturbance. Overall, my results show that plover use of prairie dog colonies was influenced by landscape and habitat features of colonies, and suggest that large colonies are particularly valuable because they are most likely to contain adequate areas with preferred habitat characteristics.     

Biodeterioration of cinematographic cellulose triacetate by Sphingomonas paucimobilis using indirect impedance and chemiluminescence techniques

The bacterium Sphingomonas paucimobilis, isolated from cinematographic films in an earlier project, was able to biodeteriorate the cellulose triacetate material (acetylation degree of 2.7). Film colonization was monitored by the indirect impedance technique and the production of carbon dioxide. The presence of ruggedness and irregularities on the surface of the film, produced when the plasticizer was extracted, accelerated the biodeterioration of the material. In contrast, cinematographic films with their layered structure made of photographic gelatine emulsion were protected and no colonization was observed. The cinematographic film without photographic emulsion reached a 5% level of biodeterioration after six weeks of incubation, confirming the possibility of biodeterioration of archival cinematographic materials if conservation conditions are not adequate. Through viscosity measurements, a decrease in relative viscosity was observed on the biodeteriorated sample, with respect to the original material, confirming a lower molecular weight as a result of enzymatic activity of S. paucimobilis. Also, using chemiluminescence, the film surface oxidation on the biodeteriorated sample was observed. This technique was very sensitive in detecting material oxidation by reactive oxygen species generated by bacteria, and could be useful to study microbiological biodeterioration in polymeric materials.     

Contamination of mural paintings by indoor airborne fungal spores

Summary The processes of biodeterioration on mural paintings have often been discussed, whereas the causes of contamination have seldom been examined.Many microorganisms responsible for the biodeterioration of paintings are of airborne origin. It follows that an investigation on the aerial microbial concentration and air movements in painted indoors is very useful.This paper reviews the literature of mural painting biodeterioration and the aerobiological studies of painted indoors. Hypogean environments, for their particular microclimatic conditions, are not considered.The fungal species most frequently found in the biodeterioration of wall-paintings are reported, as well as comparisons of surface contamination and aerobiological investigation.This review shows the necessity of finding the best sampling methodologies for cultural heritage studies. The control of airborne contamination and proper sampling methods are highly important in determining treatment strategies for the conservation and prevention of microbial attack on painted surfaces.     

A new chromogenic agar medium for detection of potentially virulent Yersinia enterocolitica

Several outbreaks of foodborne yersiniosis have been documented and this disease continues to be source of infections transmitted through foods. The selective agars most commonly used to isolate Yersinia enterocolitica in clinical, food and environmental samples, cefsulodin-irgasan-novobiocin (CIN) and MacConkey (MAC) agars, lack the ability to differentiate potentially virulent Y. enterocolitica from other Yersinia that may be present as well as some other bacterial spp. This study proposes the use of an agar medium, Y. enterocolitica chromogenic medium (YeCM), for isolation of potentially virulent Y. enterocolitica. This agar contains cellobiose as the fermentable sugar, a chromogenic substrate and selective inhibitors for suppression of colony formation by many competing bacteria. All strains of potentially virulent Yersinia of biotypes 1B, and biotypes 2-5 formed convex, red bulls-eye colonies on YeCM that were very similar to those described for CIN agar. However, Y. enterocolitica biotype 1A and other related Yersinia formed colonies that were purple/blue on YeCM while they formed typical red bulls-eye colonies on CIN agar. When a mixture of potentially virulent Y. enterocolitica biotype 1B, Y. enterocolitica biotype 1A and 5 other bacterial species was used to artificially contaminate tofu and then spread-plated on three selective agars, Y. enterocolitica biotype 1B colonies were easily distinguished from other strains on YeCM. However, Y. enterocolitica biotype 1B colonies were indistinguishable from many other colonies on CIN and only distinguishable from those of C. freundii on MAC. When colonies were picked and identified from these agars, typical colonies from YeCM were confirmed only as Y. enterocolitica biotype 1B. Typical colonies on CIN and MAC were found to belong to several competing species and biotypes.     

Independent studies using deep sequencing resolve the same set of core bacterial species dominating gut communities of honey bees

Starting in 2003, numerous studies using culture-independent methodologies to characterize the gut microbiota of honey bees have retrieved a consistent and distinctive set of eight bacterial species, based on near identity of the 16S rRNA gene sequences. A recent study [Mattila HR, Rios D, Walker-Sperling VE, Roeselers G, Newton ILG (2012) Characterization of the active microbiotas associated with honey bees reveals healthier and broader communities when colonies are genetically diverse. PLoS ONE 7(3): e32962], using pyrosequencing of the V1-V2 hypervariable region of the 16S rRNA gene, reported finding entirely novel bacterial species in honey bee guts, and used taxonomic assignments from these reads to predict metabolic activities based on known metabolisms of cultivable species. To better understand this discrepancy, we analyzed the Mattila et al. pyrotag dataset. In contrast to the conclusions of Mattila et al., we found that the large majority of pyrotag sequences belonged to clusters for which representative sequences were identical to sequences from previously identified core species of the bee microbiota. On average, they represent 95% of the bacteria in each worker bee in the Mattila et al. dataset, a slightly lower value than that found in other studies. Some colonies contain small proportions of other bacteria, mostly species of Enterobacteriaceae. Reanalysis of the Mattila et al. dataset also did not support a relationship between abundances of Bifidobacterium and of putative pathogens or a significant difference in gut communities between colonies from queens that were singly or multiply mated. Additionally, consistent with previous studies, the dataset supports the occurrence of considerable strain variation within core species, even within single colonies. The roles of these bacteria within bees, or the implications of the strain variation, are not yet clear.     

Fungal colonization on excavated prehistoric wood: Implications for in-situ display

Excavations at the Neolithic settlement of Dispilio, Greece, have revealed significant amounts of waterlogged wood, some of which is being considered for in-situ display. This study investigated the presence of fungi and their biodeterioration patterns on the excavated material. Data will be used to assess the current threat from degradation and to aid in the design of appropriate control measures for any future display strategy. Fungi were isolated using different culture media and species were identified from slide cultures using light and fluorescence microscopy. Wood micro-morphology was examined using scanning electron and light microscopy. Seventeen fungal species were identified, all of which are typical terrestrial species, suggesting that they have developed in the exposed, post-excavation environment, rather than under waterlogged burial conditions. According to the literature many of the isolated species are potential wood deteriogens. In addition to fungi, abundant bacterial growth was observed in most samples. Microscopic examination of wood cells showed patterns of decay associated with soft-rot fungi, and tunnelling and erosion bacteria, suggesting past attack related to the waterlogged burial environment. The results obtained indicated fungal colonization of exposed timbers, presenting a potential threat to their long-term survival. Any in-situ display strategy, such as continuous or periodic water-spraying of the excavated wood, should include measures to monitor and control fungal growth.     

Microbial communities adhering to the obverse and reverse sides of an oil painting on canvas: identification and evaluation of their biodegradative potential

In this study, we investigated and compared the microbial communities adhering to the obverse and the reverse sides of an oil painting on canvas exhibiting signs of biodeterioration. Samples showing no visible damage were investigated as controls. Air samples were also analysed, in order to investigate the presence of airborne microorganisms suspended in the indoor atmosphere. The diversity of the cultivable microorganisms adhering to the surface was analysed by molecular techniques, such as RAPD analysis and gene sequencing. DGGE fingerprints derived from DNA directly extracted from canvas material in combination with clone libraries and sequencing were used to evaluate the non-cultivable fraction of the microbial communities associated with the material. By using culture-dependent methods, most of the bacterial strains were found to be common airborne, spore-forming microorganisms and belonged to the phyla Actinobacteria and Firmicutes, whereas culture-independent techniques identified sequenced clones affiliated with members of the phyla Actinobacteria and Proteobacteria. The diversity of fungi was shown to be much lower than that observed for bacteria, and only species of Penicillium spp. could be detected by cultivation techniques. The selected strategy revealed a higher microbial diversity on the obverse than on the reverse side of the painting and the near absence of actively growing microorganisms on areas showing no visible damage. Furthermore, enzymatic activity tests revealed that the most widespread activities involved in biodeterioration were esterase and esterase lipase among the isolated bacterial strains, and esterase and N-acetyl-β-glucosaminidase among fungi strains.     

A new species of Devosia that forms a unique nitrogen-fixing root-nodule symbiosis with the aquatic legume Neptunia natans (L.f.) druce

Rhizobia are the common bacterial symbionts that form nitrogen-fixing root nodules in legumes. However, recently other bacteria have been shown to nodulate and fix nitrogen symbiotically with these plants. Neptunia natans is an aquatic legume indigenous to tropical and subtropical regions and in African soils is nodulated by Allorhizobium undicola. This legume develops an unusual root-nodule symbiosis on floating stems in aquatic environments through a unique infection process. Here, we analyzed the low-molecular-weight RNA and 16S ribosomal DNA (rDNA) sequence of the same fast-growing isolates from India that were previously used to define the developmental morphology of the unique infection process in this symbiosis with N. natans and found that they are phylogenetically located in the genus Devosia, not Allorhizobium or RHIZOBIUM: The 16S rDNA sequences of these two Neptunia-nodulating Devosia strains differ from the only species currently described in that genus, Devosia riboflavina. From the same isolated colonies, we also located their nodD and nifH genes involved in nodulation and nitrogen fixation on a plasmid of approximately 170 kb. Sequence analysis showed that their nodD and nifH genes are most closely related to nodD and nifH of Rhizobium tropici, suggesting that this newly described Neptunia-nodulating Devosia species may have acquired these symbiotic genes by horizontal transfer.     

Colony breeding system influences cuticular bacterial load of Formosan subterranean termite (Isoptera: Rhinotermitidae) workers

The goal of this study was to test whether the breeding system and/or the degree of inbreeding of field colonies of the Formosan subterranean termite, Coptotermes formosanus, Shiraki (Isoptera: Rhinotermitidae) influences bacterial load on the cuticle of foraging workers. We enumerated bacterial load on the cuticle of groups of workers foraging in 20 inground monitoring stations surrounding the French Market in New Orleans, LA, and identified bacteria species using 16S rRNA gene sequencing. We used microsatellite genotyping to assign the 20 worker groups to seven simple family colonies (headed by a single pair of reproductives) and four extended family colonies (headed by multiple inbreeding reproductives) with a wide range of degrees of inbreeding. Workers from extended family colonies had a higher bacterial load than those from simple family colonies; however, bacterial load was not significantly correlated to the degree of inbreeding, possibly because of confounding factors in colony life history, such as age and/or size of colonies. Colonies with high bacterial load did not have a higher proportion of entomopathogens, and thus, bacterial load is not necessarily an indicator for disease risk. The majority of bacteria cultured from the cuticle of termites were soil bacteria with no known pathology against termites.     

Recruiting juvenile damselfish: the process of recruiting into adult colonies in the damselfish Stegastes nigricans

Juveniles of Stegastes nigricans occur in adult colonies, solitarily, and occasionally in juvenile colonies. We concentrated on solitary juveniles and those in adult colonies. We examined the costs and benefits of different settlement strategies, quantified the territory requirements of adults, and investigated the process of how juveniles make the transition to adult territorial fish. An adequate adult territory lies next to those of other adults, is proportional in area to the size of the adult, and contains a refuge tunnel whose entrance is sufficiently large. Compared with solitary juveniles, those <4 cm total length inhabiting adult colonies experienced reduced heterospecific competition for algal food and consequently benefited from a greater density of algae. A cost of recruiting into an adult colony, however, was increased attacks by adults. Juveniles that settled in adult colonies avoided attacks by retreating into small holes inaccessible to adults. As juveniles in adult colonies grew, they were chased less often by adults, whereas they themselves chased adults and heterospecific fish more often. Because territory size correlated with fish size in adult colonies, its area had to expand as the young fish grew, and that expansion was done at the expense of neighbors. Obtaining the space needed by an adult may be possible only when the juvenile settles directly into an adult colony. Juveniles that first settle down solitarily, or in juvenile colonies, may later attempt to enter adult colonies. However, because they do so as larger juveniles, they would have difficulty insinuating themselves into small refuges, which is essential for retreat from the adults. Received in revised form: 4 January 2001 Electronic Publication     

Regulation of Bacterial Communities Through Antimicrobial Activity by the Coral Holobiont

Interactions between corals and associated bacteria and amongst these bacterial groups are likely to play a key role in coral health. However, the complexity of these interactions is poorly understood. We investigated the functional role of specific coral-associated bacteria in maintaining microbial communities on the coral Acropora millepora (Ehrenberg 1834) and the ability of coral mucus to support or inhibit bacterial growth. Culture-independent techniques were used to assess bacterial community structures whilst bacterial culture was employed to assess intra- and inter-specific antimicrobial activities of bacteria. Members of Pseudoalteromonas and ribotypes closely related to Vibrio coralliilyticus displayed potent antimicrobial activity against a range of other cultured isolates and grew readily on detached coral mucus. Although such bacterial ribotypes would be expected to have a competitive advantage, they were rare or absent on intact and healthy coral colonies growing in situ (analysed using denaturing gradient gel electrophoresis and 16S rRNA gene sequencing). The most abundant bacterial ribotypes found on healthy corals were Gammaproteobacteria, previously defined as type A coral associates. Our results indicate that this group of bacteria and specific members of the Alphaproteobacteria described here as ‘type B associates’ may be important functional groups for coral health. We suggest that bacterial communities on coral are kept in check by a combination of host-derived and microbial interactions and that the type A associates in particular may play a key role in maintaining stability of microbial communities on healthy coral colonies.     

Indirect effects of a non-target species, Pyrrhalta luteola (Chrysomelidae) on the biodeterioration of Brussels tapestries

Treatments to preserve artwork are usually designed to control for known target species. Nevertheless, indirect effects of non-target species may cause important biodeterioration. During the restoration of a series of Brussels tapestries preserved in the Abbey of Sacromonte (Granada, Spain), we studied one of the tapestries which presented a high degree of deterioration, principally large losses of material and color alterations. We found important biodeterioration effects produced by a non-target insect species, the beetle Pyrrhalta luteola (Chrysomelidae). We raised P. luteola beetles in the laboratory on different constituent materials to identify the effects of this insect on the tapestry. Results showed that beetle remains were mainly responsible for the chromatic changes. Although beetles did not consume textile materials, and had not direct effects in tapestry destruction, its presence indirectly affected the tapestry due to the higher mold-growth obtained in samples of materials with beetle remains. Based on these results, we propose some recommendations to consider control for these potential biodeterioration agents in artwork conservation programs.     

Plasmid screening at high colony density

A procedure is described for screening bacterial colonies containing recombinant plasmids by nucleic acid hybridization at high density i.e., at 100000 colonies per 150 mm diameter plate. Small colonies are established on nitrocellulose filters from which they can be faithfully replicated to additional filters. Chloramphenicol amplification may be carried out in situ before screening. The filters may be kept frozen for long-term storage of colonies which may be further replicated after thawing.     

Ultrastructure of interaction in alginate beads between the microalga Chlorella vulgaris with its natural associative bacterium Phyllobacterium myrsinacearum and with the plant growth-promoting bacterium Azospirillum brasilense

Chlorella vulgaris, a microalga often used in wastewater treatment, was coimmobilized and coincubated either with the plant growth-promoting bacterium Azospirillum brasilense, or with its natural associative bacterium Phyllobacterium myrsinacearum, in alginate beads designed for advanced wastewater treatment. Interactions between the microalga and each of the bacterial species were followed using transmission electron microscopy for 10 days. Initially, most of the small cavities within the beads were colonized by microcolonies of only one microorganism, regardless of the bacterial species cocultured with the microalga. Subsequently, the bacterial and microalgal microcolonies merged to form large, mixed colonies within the cavities. At this stage, the effect of bacterial association with the microalga differed depending on the bacterium present. Though the microalga entered a senescence phase in the presence of P. myrsinacearum, it remained in a growth phase in the presence of A. brasilense. This study suggests that there are commensal interactions between the microalga and the two plant associative bacteria, and that with time the bacterial species determined whether the outcome for the microalga is senescence or continuous multiplication.     

Ecology and taxonomy of bacteria attaching to wood surfaces in a tropical harbor.

Water, sediment, and wooden pilings, samples of which were collected from a harbor in Puerto Rico during the course of a long-term study of biofouling of wood treated with creosote and related compounds, were found to support growth of microbial populations, the dominant taxa of which included Hyphomicrobium, Hyphomonas, Pseudomonas, Vibrio, and Bacillus. New wood exposed to the harbor water was rapidly colonized by Hyphomicrobium vulgare. Old pilings in an advanced stage of biodeterioration maintained a diverse bacterial microflora, representatives of which were also found widely distributed in the water column and sediment. Evidence for bacterial species succession was obtained, indicating that microbial interactions are important for attachment to, and subsequent colonization of, wood surfaces in the marine environment.     

A behavioural reconnaissance of some Jamaican reef fishes

Three major social systems were observed: territorial, isolate, and gregarious. Territorials defend a particular area against intruders. Isolates neither chase conspecifics nor join other individuals, while gregarious species are found in groups. Some species of territorial pomacentrids were found in uni-specific colonies. As gregarious groups neared these colonies, they were attacked by several territorials. The number of chases directed against the various species of intruders was in proportion to the intruder's abundance in the study areas. Predators were uncommon and generally ignored. Isolates were either predators, or slow moving species. Gregarious species could be found in uni-specific or mixed-species groups. In mixed-species groups, there were three subunits: core, associate, and opportunist. Core species were always in the majority and led the group. Associates followed the core species for long periods of time and the opportunists were brief visitors. Quantitative comparisons between uni-specific and mixed-species groups revealed that associates tend to select the larger of the available core groups. Juveniles were also considered and compared to their adults. Juveniles did exhibit the general types of social behaviour found in adults. However, within a species, the adult's behaviour may be very different from their own juveniles. The coral, and the chases by pomacentrids, were related to the formation and dispersion of gregarious groups.