Metal concentrations in Sargassum algae from coastal waters of Nha Trang Bay (South China Sea)

The concentrations of metals, viz., Fe, Mn, Cu, Zn, Cd, Pb, and Ni, were investigated in brown algae of the genus Sargassum collected in the coastal waters of Nha Trang Bay (South China Sea). Metal concentrations in algae growing in the zone of influence of the city of Nha Trang were higher than those in macrophytes collected to the south and north of the city. Similar levels of Cu and Fe concentrations were observed in macrophytes from the urbanized coastal areas of Nha Trang Bay and in algae from the Peter the Great Bay (Sea of Japan). This is suggestive of comparable metal inputs from the anthropogenic sources of the cities of Nha Trang and Vladivostok (Peter the Great Bay). However, the concentrations of Pb, Ni, and Cd in algae from the coastal waters of Nha Trang Bay were lower than in macrophytes from the inshore zone of Vladivostok. The high level of pollution of sea water with Zn compounds near Nha Trang was local. The metal levels in macrophytes from background areas reflect the geochemical features of the environment. Sargassum algae from Nha Trang Bay had lower concentrations of Zn, Cd, and Ni and higher concentrations of Mn than algae from Peter the Great Bay. The background concentrations of Cu, Pb, and Fe in macrophytes from both bays were virtually the same.     

Changes in the composition and structure of coral communities of Mju and Moon islands, Nha Trang Bay, South China Sea

In October 2003 and January 2005, comparative observations were made on the reefs of Mju and Moon islands near the city and port of Nha Trang, which we first investigated in 1981. Appreciable changes due to anthropogenic impact have occurred on the reefs that are the nearest to the city. There was a reduction in substrate cover by reef-building corals, a substitution of dominant scleractinian species, and a decrease in the numbers and diversity of common species of corallobionts. The index of species diversity for scleractinians also decreased. The seaweeds Chnoospora and Halimeda spread into all zones of the reefs. Changes in coral communities on more distant and protected reefs were not so marked.     

Algal fouling of underwater structures at lobster farms in Nha Trang Bay (Vietnam)

The species composition and structure of algal fouling communities on the underwater artificial substrates at lobster farms in Nha Trang Bay (Vietnam) were studied for the first time. In total, 126 taxa (species and forms) of macroalgae (24% green, 16% brown, and 60% red), as well as eight species of cyanobacteria, were found. Depending on the area and quality of the substrate, fouling algae form polydominant turf communities, mono- and bidominant communities of crustose algae, or no specific communities. The flora of macroalgal fouling at lobster farms in Nha Trang Bay was similar in terms of its diversity and species composition to that of coral reefs in areas of the Indo-Pacific with a low level of pollution. This similarity might be due to the diversity and cleanness of the substrates (the absence of sediment on the surface of the underwater structures).     

Coral Mucus Is a Hot Spot for Viral Infections

There is increasing suspicion that viral communities play a pivotal role in maintaining coral health, yet their main ecological traits still remain poorly characterized. In this study, we examined the seasonal distribution and reproduction pathways of viruses inhabiting the mucus of the scleractinians Fungia repanda and Acropora formosa collected in Nha Trang Bay (Vietnam) during an 11-month survey. The strong coupling between epibiotic viral and bacterial abundance suggested that phages are dominant among coral-associated viral communities. Mucosal viruses also exhibited significant differences in their main features between the two coral species and were also remarkably contrasted with their planktonic counterparts. For example, their abundance (inferred from epifluorescence counts), lytic production rates (KCN incubations), and the proportion of lysogenic cells (mitomycin C inductions) were, respectively, 2.6-, 9.5-, and 2.2-fold higher in mucus than in the surrounding water. Both lytic and lysogenic indicators were tightly coupled with temperature and salinity, suggesting that the life strategy of viral epibionts is strongly dependent upon environmental circumstances. Finally, our results suggest that coral mucus may represent a highly favorable habitat for viral proliferation, promoting the development of both temperate and virulent phages. Here, we discuss how such an optimized viral arsenal could be crucial for coral viability by presumably forging complex links with both symbiotic and adjacent nonsymbiotic microorganisms.     

Reproductive features of <Emphasis Type="Italic">Upeneus margarethae</Emphasis> (Mullidae), a species recorded in the coastal zone of Vietnam for the first time

The species Upeneus margarethae described recently from the western Indian Ocean is recorded in the coastal zone of Vietnam for the first time. The reproductive features of the representatives of the species from southern Central Vietnam (Nha Trang Bay), Central Vietnam (Da Nang), and North Vietnam (Ha Long Bay) are studied. Based on the analysis of maturity stages of female’s ovaries and gonadosomatic index, the fishes spawn over the entire year in Central Vietnam, but the spawning interruption is observed in North Vietnam during a winter season. In Nha Trang Bay, 50% of females reach sexual maturity at the body length (FL) 9.8 cm. Based on histological structure of ovaries and frequency distribution of oocyte diameter before the spawning, the oogenesis is continuous. Anomalous oocyte structure is registered in 20% of the females. Egg morphology is described for 3 h after activation of ovulated oocytes. A comparison of reproductive parameters in U. margarethae and U. tragula is conducted.     

Dragonets (Callionymidae) of soft bottoms from the coastal zone of southern Central Vietnam

A review of dragonets (Gallionymidae) from the coastal waters of Khanh Hoa (Nha Trang and Van Phong bays) and Binh Thuan (Phu Quy Island) provinces, Vietnam, was conducted based on the samples of the author. In total, nine species were recorded, including three species indicated in the fauna of the country for the first time. In addition, geographic and bathymetric distribution of C. altipinnis, as well as morphological variation of several other species, was specified.     

Two new species of fishes from families Muraenidae (Anguilliformes) and Mugiloididae (Perciformes) from the Waters of Vietnam

New species of the genera Gymnothorax (fam. Muraenidae) and Parapercis (fam. Mugiloididae) are described from coastal waters of central Vietnam. G. emmae sp. n. is a common species all along the coast from the Van Phong Bay to the Phan Thiet Bay and differs from other species of this genus in characters of coloration, dentition, and the vertebral formula. P. bicoloripes sp. n. is common in the Phan Thiet Bay and is also know from one specimen from the Nha Trang Bay; from other species of the genus, it differs in coloration and meristic characters.     

Accumulation of rare earth elements in human bone within the lifespan

For the first time, the contents of rare earth elements (REEs) in a rib bone of a healthy human were determined. The mean value of the contents of Ce, Dy, Er, Gd, La, Nd, Pr, Sm, Tb, and Yb (10 elements out of 17 total REEs), as well as the upper limit of means for Ho, Lu, Tm, and Y (4 elements) were measured in the rib bone tissue of 38 females and 42 males (15 to 55 years old) using inductively coupled plasma mass spectrometry (ICP-MS). We found age-related accumulation of REEs in the bone tissue of healthy individuals who lived in a non-industrial region. It was calculated that during a lifespan the content of REEs in a skeleton of non-industrial region residents may increase by one to two orders of magnitude. Using our results as indicative normal values and published data we estimated relative Gd accumulation in the bone tissue of patients according to magnetic resonance imaging with contrast agent and La accumulation in the bone tissue of patients receiving hemodialysis after treatment with lanthanum carbonate as a phosphate binder. It was shown that after such procedures contents of Gd and La in the bone tissue of patients are two to three orders of magnitude higher than normal levels. In our opinion, REEs incorporation may affect bone quality and health similar to other potentially toxic trace metals. The impact of elevated REEs content on bone physiology, biochemistry and morphology requires further investigation.     

Anthropogenic disturbance of coastal habitats promotes the spread of the introduced scleractinian coral Oculina patagonica in the Mediterranean Sea

The extensive human-mediated modifications of shallow coastal habitats drastically alter selection regimes and may assist alien invasions. The preferential presence of a non-indigenous scleractinian coral (Oculina patagonica) on anthropogenic hard substrata was investigated in a highly disturbed coastal area, along the eastern Saronikos Gulf (Aegean Sea, Eastern Mediterranean). Although the species occurred on both natural and anthropogenic substrata at similar frequencies, its abundance was substantially higher on the latter. The species was present all along the shallow (0.5–5 m) infralittoral zone of the studied coastline, and its percent cover even exceeded 50 % at a site of anthropogenic hard substratum. The occupancy of the species declined with distance from a highly disturbed industrialized/urbanized area (Athens metropolitan coastal front and the port of Piraeus). Space availability as a result of habitat modification appears to have been an important factor enhancing the coral’s abundance in this area. The ongoing degradation of the coastal zone, as a combined effect of coastal pollution, proliferation of artificial substrata and overgrazing seems to be paving the way to this new invasion in the Aegean Sea.     

Association of pneumococcal carriage in infants with the risk of carriage among their contacts in Nha Trang,Vietnam: A nested cross-sectional survey

BackgroundInfants are at highest risk of pneumococcal disease. Their added protection through herd effects is a key part in the considerations on optimal pneumococcal vaccination strategies. Yet, little is currently known about the main transmission pathways to this vulnerable age group. Hence, this study investigates pneumococcal transmission routes to infants in the coastal city of Nha Trang, Vietnam.Methods and findingsIn October 2018, we conducted a nested cross-sectional contact and pneumococcal carriage survey in randomly selected 4- to 11-month-old infants across all 27 communes of Nha Trang. Bayesian logistic regression models were used to estimate age specific carriage prevalence in the population, a proxy for the probability that a contact of a given age could lead to pneumococcal exposure for the infant. We used another Bayesian logistic regression model to estimate the correlation between infant carriage and the probability that at least one of their reported contacts carried pneumococci, controlling for age and locality. In total, 1,583 infants between 4 and 13 months old participated, with 7,428 contacts reported. Few infants (5%, or 86 infants) attended day care, and carriage prevalence was 22% (353 infants). Most infants (61%, or 966 infants) had less than a 25% probability to have had close contact with a pneumococcal carrier on the surveyed day. Pneumococcal infection risk and contact behaviour were highly correlated: If adjusted for age and locality, the odds of an infant’s carriage increased by 22% (95% confidence interval (CI): 15 to 29) per 10 percentage points increase in the probability to have had close contact with at least 1 pneumococcal carrier. Moreover, 2- to 6-year-old children contributed 51% (95% CI: 39 to 63) to the total direct pneumococcal exposure risks to infants in this setting. The main limitation of this study is that exposure risk was assessed indirectly by the age-dependent propensity for carriage of a contact and not by assessing carriage of such contacts directly.ConclusionsIn this study, we observed that cross-sectional contact and infection studies could help identify pneumococcal transmission routes and that preschool-age children may be the largest reservoir for pneumococcal transmission to infants in Nha Trang, Vietnam.     

Biodiversity and Enzyme Activity of Marine Fungi with 28 New Records from the Tropical Coastal Ecosystems in Vietnam

The coastal marine ecosystems of Vietnam are one of the global biodiversity hotspots, but the biodiversity of marine fungi is not well known. To fill this major gap of knowledge, we assessed the genetic diversity (ITS sequence) of 75 fungal strains isolated from 11 surface coastal marine and deeper waters in Nha Trang Bay and Van Phong Bay using a culture-dependent approach and 5 OTUs (Operational Taxonomic Units) of fungi in three representative sampling sites using next-generation sequencing. The results from both approaches shared similar fungal taxonomy to the most abundant phylum (Ascomycota), genera (Candida and Aspergillus) and species (Candida blankii) but were different at less common taxa. Culturable fungal strains in this study belong to 3 phyla, 5 subdivisions, 7 classes, 12 orders, 17 families, 22 genera and at least 40 species, of which 29 species have been identified and several species are likely novel. Among identified species, 12 and 28 are new records in global and Vietnamese marine areas, respectively. The analysis of enzyme activity and the checklist of trophic mode and guild assignment provided valuable additional biological information and suggested the ecological function of planktonic fungi in the marine food web. This is the largest dataset of marine fungal biodiversity on morphology, phylogeny and enzyme activity in the tropical coastal ecosystems of Vietnam and Southeast Asia. Biogeographic aspects, ecological factors and human impact may structure mycoplankton communities in such aquatic habitats.     

Annotated checklist of species of the family pomacanthidae (Actinopterygii,Perciformes) from the Nha Trang Bay (South China Sea,Central Vietnam)

Angelfishes (Fam. Pomacanthidae) of the Nha Trang Bay (Central Vietnam) are reviewed. Fourteen species of pomacanthids belonging to six genera (Apolemichthys, Centropyge, Chaetodontoplus, Genicanthus, Pomacanthus, and Pygoplites) are recorded in the bay. All species are identified on preserved material. Two new species for the bay are found: Centropyge bispinosa and C. heraldi. C. herald is new species for coastal waters of Continental Vietnam and of adjacent areas. For all pomacanthid species of the bay, areas are described, brief diagnostic characteristics are supplied, and distribution by biotopes and depths is indicated based on data of underwater observations.     

Gurnards of the Genus Pterygotrigla (Triglidae) of Nha Trang Bay and Adjacent Waters (Vietnam,South China Sea)

Journal of Ichthyology - An overview of the species of gurnards of the genus Pterygotrigla, found in Nha Trang Bay and the adjacent water area of the South China Sea (south of Central Vietnam) has...     

Microelement composition of the green alga Ulva fenestrata from Peter the Great Bay, Sea of Japan

Concentrations of heavy metals Fe, Mn, Cu, Zn, Pb, Cd, and Ni were determined in the thalluses of the green alga Ulva fenestrata sampled from different locations in Peter the Great Bay (Sea of Japan). According to the metal concentrations in Ulva, the degree of pollution of the surveyed areas in Peter the Great Bay decreases in the following series: Amur Bay > Ussuri Bay > Nakhodka Bay > Vostok Bay > the water area of Far Eastern State Marine Nature Biosphere Reserve. The microelement composition of Ulva from open-shore stations reflects the heavy metal pollution level of water areas as a whole. The concentrations of trace elements in U. fenestrata from closed coastal areas are indicative of marine coastal water pollution from local sources. Generally, metal concentrations in U. fenestrata from Peter the Great Bay are similar to heavy metal levels in non-polluted or weakly polluted coastal areas of the world.     

Planktonic and symbiotic organisms in nutrition of coralobiont fish

Nutrition of coral reef fish closely associated with the colonies of scleractinian corals Acropora spp. (South China Sea, Gulf of Nha Trang) was investigated. Parabionts Dascyllus reticulatus and Chromis caeruleus (Pomacentridae) feed mainly on zooplankton in the water column above the hosts’ colony, and inbionts Gobiodon quinquestrgatus (Gobiidae) rarely leave a host colony and feed generally on coral reef invertebrates. A high part of secondary nutrition objects (on average 19–29%) that indicates deficiency in main food were noted in both categories of fish. Food of all three fish species contains parasites (from 19% in C. caeruleus and up to 25% in G. quinquestrigatus) whose significant part is represented by parasites of coral (approximately 7% in D. reticulatus and C. caeruleus and 15% in G. quinquestrigatus). In addition, larvae of parasites of Isopoda and Facetotecta that are fed by fish in the water column were found. Mucus from the surface of host coral which was recognized on the basis of a high number of nematocysts in fish stomachs was found in food of G. quinquestrigatus for the first time. Positive and negative effects of symbiosis of fish and host-coral were discussed. A commensal character of symbiosis was supposed.     

The fauna of the South China Sea include unknown phoronid species: new records of larvae and adults

The Phoronida is a phylum of marine invertebrates that have a worldwide distribution and that form huge benthic aggregations in many aquatic areas. Although there are only 11 recognized species of phoronids, many species clearly remain to be described. The matching of larval and adult stages of the same species will help indicate which larvae belong to described species and which represent undescribed species whose adults have yet to be found. Larvae of four phoronid species were collected in Nha Trang Bay and investigated by light microscopy and molecular methods. Three of the described larvae belong to new phoronid species that have yet to be named. These larvae have unique morphological features and occupy separate positions on the phylogenetic tree of phoronids. One of the described larvae belongs to Phoronis hippocrepia or to a closely related species. Observations made with a new macrophotographic method indicated that Phoronopsis californica also occurs in Nha Trang Bay. Thus, according to records of larvae and adults, Nha Trang Bay contains at least nine phoronid species: Phoronopsis californica, Phoronopsis malakhovi, Phoronis australis, Phoronis hippocrepia (or a closely related species), three unknown phoronid species whose larvae have unique morphological features and that apparently belong to the genus Phoronis, and two species, whose adults have unique set of morphological features. The richness of phoronids in this area suggests that the Indo-Pacific is a centre of phoronid biodiversity.