Early bacterial biofilm colonizers in the coastal waters of Mauritius

Background: The past years have witnessed a growing number of researches in biofilm forming communities due to their environmental and maritime industrial implications. To gain a better understanding of the early bacterial biofilm community, microfiber nets were used as artificial substrates and incubated for a period of 24 h in Mauritian coastal waters. Next-generation sequencing technologies were employed as a tool for identification of early bacterial communities. Different genes associated with quorum sensing and cell motility were further investigated. Results: Proteobacteria were identified as the predominant bacterial microorganisms in the biofilm within the 24 h incubation, of which members affiliated to Gammaproteobacteria, Alphaproteobacteria and Betaproteobacteria were among the most abundant classes. The biofilm community patterns were also driven by phyla such as Firmicutes, Bacteroidetes, Chloroflexi, Actinobacteria and Verrucomicrobia. The functional analysis based on KEGG classification indicated high activities in carbohydrate, lipid and amino acids metabolism. Different genes encoding for luxI, lasI, agrC, flhA, cheA and cheB showed the involvement of microbial members in quorum sensing and cell motility. Conclusion: This study provides both an insight on the early bacterial biofilm forming community and the genes involved in quorum sensing and bacterial cell motility.

Faunal data and envenomation emergency first aid of cone snails (Conus spp.) in Qeshm Island, the Persian Gulf

OBJECTIVE@#To investigate the fauna of a highly venomous marine species group, the cone snails (Family Conidae), in the shores of Qeshm Island, of evaluating the possibility of envenomation in the area and summarize recommendations for emergency first aid.@*METHODS@#Shores surrounding Qeshm Island were surveyed to collect cone snails during cold (February and March) and warm (May and June) seasons of 2017. Collected snails were identified to the species level. Abundance and species richness were estimated in shores of different structures, including muddy and sandy-rocky shores. Also, the most updated medical literature was reviewed to summarize related emergency first aid.@*RESULTS@#Three cone snail species were recorded from southern sandy-rocky shores of the Island, in decreasing order of abundance, included crowned cone (Conus coronatus) (65%), feathered cone (Conus pennaceus) (28%), and frigid cone (Conus frigidus) (7%). Abundance of these species were significantly higher in cold season compared to the warm season (P < 0.05). No cone snails were recorded along the northern muddy shores of the Island.@*CONCLUSIONS@#Envenomation can cause various symptoms ranging from minor local pain to systemic paralysis and death due to respiratory failure. We recommend an awareness programme for the seashore visiting public.

Faunal data and envenomation emergency first aid of cone snails (Conus spp.) in Qeshm Island, the Persian Gulf

Objective To investigate the fauna of a highly venomous marine species group, the cone snails (Family Conidae), in the shores of Qeshm Island, of evaluating the possibility of envenomation in the area and summarize recommendations for emergency first aid. Methods Shores surrounding Qeshm Island were surveyed to collect cone snails during cold (February and March) and warm (May and June) seasons of 2017. Collected snails were identified to the species level. Abundance and species richness were estimated in shores of different structures, including muddy and sandy-rocky shores. Also, the most updated medical literature was reviewed to summarize related emergency first aid. Results Three cone snail species were recorded from southern sandy-rocky shores of the Island, in decreasing order of abundance, included crowned cone (Conus coronatus) (65%), feathered cone (Conus pennaceus) (28%), and frigid cone (Conus frigidus) (7%). Abundance of these species were significantly higher in cold season compared to the warm season (P < 0.05). No cone snails were recorded along the northern muddy shores of the Island. Conclusions Envenomation can cause various symptoms ranging from minor local pain to systemic paralysis and death due to respiratory failure. We recommend an awareness programme for the seashore visiting public.

Phytoplankton diversity in the Parangipettai coastal waters, southeast coast of India.

An investigation was carried out during June 2005 to May 2007 on hydrography, composition and community structure of phytoplankton including chlorophyll a in Parangipettai coastal waters (southeast coast of India). Air and surface water temperatures varied from 25.5 to 31.2 °C and from 25 to 29.3°C, respectively. Salinity values varied from 5 to 33.1‰ and the pH ranged between 7.2 and 8.3. Dissolved oxygen content varied from 3.1 to 7.9 mg l-1 while the light extinction coefficient values (LEC) ranged between 1.8 and 11.0 cm. The range of inorganic nutrients viz., nitrate, nitrite, phosphate and silicate were: 6.5 - 27.0 µM; 1.0 - 8.9 µM; 0.1 - 3.0 µM and 15.0 - 140 µM, respectively. The range of chlorophyll a was: 2.0 - 7.5 µg l-1. Presently, 117 phytoplankton species representing different classes viz: Bacillariophyceae (66); Dinophyceae (22); Cyanophyceae (19); Chlorophyceae (7) and Chrysophyceae (3) were recorded. The phytoplankton cell abundance varied from 0.14 to 132 cells ml-1, with peak diversity (3.52 bits ind.-1) during summer season. The maximum abundance was found during summer season coinciding with the stable hydrographical conditions. Canonical Correspondence Analysis was applied in this study for discriminating environmental factors effecting on phytoplankton community at species level.

Studies on water quality and pathogenic bacteria in coastal water Langkawi, Malaysia.

A study on physico-chemical parameters and pathogenic bacterial community was carried out at the coastal waters of Pulau Tuba island, Langkawi. The physico-chemical parameters such as temperature (27.43-28.88oC), dissolved oxygen (3.79-6.49 mg l-1), pH (7.72-8.20), salinity (33.10-33.96 ppt), total dissolved solids (32.27-32.77 g l-1) and specific conductivity (49.83-51.63 mS cm-1) were observed. Station 3 and station 4 showed highest amount of nitrates (26.93 and 14.61 µg at N l-1) than station 1 (2.04 µg at N l-1) and station 2 (4.18 µg at N l-1). The highest concentration (12.4± µg l-1) of chlorophyll a was observed in station 4 in October 2005. High phosphorus content (561mg P l-1) was found in the station 2. Thirteen bacterial isolates were successfully identified using API 20E system. The highest amount of bacteria was observed at Station 4 (3400 CFU ml-1) and the lowest number was at Station 2 (890 CFU ml-1). Out of identified 13 Gram-negative bacterial isolates dominant species were Aeromonas hydrophila, Klebsiella oxytoca, Pseudomonas baumannii, Vibrio vulnificus, Proteus mirabilis, Providencia alcalifaciens and Serratia liquefaciens. Apart from this, oil biodegrading Pseudomonas putida were also identified. The study reveals the existing status of water quality is still conducive and the reasonably diverse with Gram-negative bacteria along the Pulau Tuba Langkawi.

Variaciones estacionales de la estructura comunitaria del fitoplancton en zonas de descarga de agua subterránea en la costa norte de la Península de Yucatán / Seasonal variations of community structures phytoplankton in groundwater discharge areas along the Northern Yucatán Peninsula coast

Seasonal variations of community structures phytoplankton in groundwater discharge areas along the Northern Yucatán Peninsula coast. The highly touristic Yucatán Peninsula is principally constituted with coastal marine environments. Like other coastal areas, this has been affected by the increase of waste water discharge, hydrological modifications and land use changes in the area. The phytoplankton community structure is one of the main components of coastal ecosystems and the most affected in hydrological processes. In order to follow the seasonal variations, the phytoplankton was characterized to follow the hydrological variability in two sites (Dzilam and Progreso) of the Northern Yucatán Peninsula. For this, cruises were carried out monthly during one year, from April 2004 to March 2005, with two samplings per season (dry, rainy and “nortes”).Hydrological variability was associated with seasonality and directly linked to groundwater discharges in the Dzilam area, and waste water discharges in the Progreso area. The highest nutrient concentrations occurred mainly during the rainy season. The phytoplankton community changes observed throughout the year suggested that the hydrological and chemical variability associated with seasonality and anthropogenic impacts have a strong influence. The substitution of diatoms by dinoflagellates as the dominant group in Progreso was the result of seasonal variability itself, but also could have been caused by eutrophic processes; while in Dzilam, the major presence of diatoms could have been favored by groundwater discharges. The results of this study can be used to understand the linkages between stressors from the anthropogenic activities and coastal water quality and changes.

La zona costera es el principal ambiente marino en la Península de Yucatán (SE, México). Sin embargo, se ha visto afectada con el incremento de las descargas de aguas residuales, modificaciones hidrológicas y cambios de uso del suelo. El fitoplancton es una de las comunidades más afectadas por la variabilidad hidrológica. Se caracterizó la estructura de la comunidad de fitoplancton en función de la variabilidad hidrológica en dos sitios (Dzilam y Progreso) a lo largo de la costa Norte de Yucatán. Se realizaron muestreos mensuales durante un año, de abril 2004 a marzo 2005, mediante dos muestreos por época (secas, lluvias y nortes). La variabilidad hidrológica se asocia al patrón climático y está ligado a los aportes de agua subterránea en Dzilam y a las aguas de desecho en Progreso. Estacionalmente, las mayores concentraciones de nutrientes se produjeron principalmente en época de lluvias. Los cambios observados en el fitoplancton a lo largo del año sugieren que la variabilidad hidrológica y química asociada a la estacionalidad y a los impactos antropogénicos tienen una fuerte influencia. La sustitución de diatomeas por dinoflagelados como grupo dominante en Progreso es el resultado de la variabilidad estacional en sí, pero también podría verse favorecido por procesos eutróficos. En Dzilam la mayor presencia de diatomeas es favorecida por las descargas de agua subterránea. Estos resultados pueden utilizarse para comprender los vínculos entre los factores de estrés de las actividades antropogénicas y la calidad del agua.

Distribution of Vibrio alginolyticus-like species in Shenzhen coastal waters, China

We investigated the distribution of vibrios in Shenzhen coastal waters in order to obtain valuable information for the aquaculture industry and a health warning system. Quantities of vibrios from surface waters ranged from 0 to 4.40×10(4) CFUs mL-1 in April (spring), while from 0 to 2.57×10³ CFUs mL-1 in September (autumn); the abundance of V. alginolyticus-like species from surface water ranged from 0 to 6.72×10³ CFUs mL-1 in April (spring) and from 0 to 1.28×10³ CFUs mL-1 in September (autumn); higher counts were observed in spring. The V. alginolyticus-like species was dominant in Shenzhen coastal waters, with the highest abundance in the clean region (stations YMK001 and GDN064) in April, suggesting that Vibrio spp. were naturally occurring bacteria in marine environments. The correlation between the abundance of vibrios (including V. alginolyticus-like species) and environmental factors varied in different regions and different seasons. There were no vibrios detected when the salinity was less than 11.15ë in the Zhujiang River estuary, which indicated that salinity played a key role in the distribution of vibrios and V. alginolyticus-like species.

Virioplankton abundance in trophic gradients of an upwelling field

This work correlates time series of biological and physical variables to the marine viruses across trophic gradients within Arraial do Cabo upwelling system, Southeast of Brazil. The objective is to investigate the major controlling factors of virioplankton dynamics among different water masses. It was used an in situ and ex situ flow cytometry for accessing the plankton community. Viruses were highly correlated to bacteria and phytoplankton, but although the lack of direct correlation with physicals, upwelling turned out to be the main contributing factor to the highest values of viral abundance and virus:bacterial ratio. Our data suggest that the lowest temperature of upwelled South Atlantic Central Waters would help to maintain a high viral abundance and higher temperatures of Coastal and Tropical Waters might be another ecological niche allowing the co-existence.