Microbial Communities in Changing Aquatic Environments.

The quality of aquatic ecosystems is an important public health concern [...].

Acetylcholinesterase activity in muscle tissue of Norway lobster Nephrops norvegicus: Importance of body size, season, sex and naturally occurring metals.

The aim of the present study was to determine the levels of acetylcholinesterase (AChE) activity in the tail muscle tissue of wild populations of Nephrops norvegicus from the Northern Adriatic, and correlate it to body size, seasons, sex and the content of mercury, arsenic, cadmium, lead and copper. The animals of both sexes were collected in spring and autumn from two relatively distant fishing grounds. A marked variability of muscle AChE activity was found (0.49 to 11.22 nmol/min/mg prot.), displaying the opposite seasonal trend between two sampling sites. Small, but significant negative correlation has been found between AChE activity and carapace length (rs = - 0.35, p < 0.05). Data reported here provide an essential baseline for future studies of neurotoxicity in crustaceans. The study highlights the necessity for continuous monitoring of potentially toxic metals in edible marine species to avoid possible repercussions of seafood consumption on human health.

Predictive modeling of microbiological seawater quality in karst region using cascade model.

This paper presents an in-depth analysis of seawater quality measurements during the bathing seasons from year 2009 to 2020 in the city of Rijeka, Croatia. Due to rare occurrences of measurements with less than excellent water quality, considered dataset is deeply imbalanced. Additionally, it incorporates measurements under the influence of submerged groundwater discharges (SGD), which were observed in some bathing locations. These discharges were previously thought to dry up during the summer season and are now suspected to be one of the causes of increased Escherichia coli values. Consequently, and in view of the fact that the accuracy of prediction models can be significantly influenced by temporal and spatial variation of the input data, a novel cascade prediction modeling strategy was proposed. It consists of a sequence of prediction models which tend to identify general environmental conditions which confidently lead to excellent bathing water quality. The proposed model uses environmental features which can rather easily be estimated or obtained from the weather forecast. The model was trained on a highly biased dataset, consisting of data from locations with and without SGD influence, and for the time period spanning extremely dry and warm seasons, extremely wet seasons, as well as normal seasons. To simulate realistic application, the model was tested using temporal and spatial stratification of data. The cascade strategy was shown to be a good approach for reliably detecting environmental parameters which produce excellent water quality. Proposed model is designed as a filter method, where instances classified as less-than-excellent water quality require further analysis. The cascade model provides great flexibility as it can be customized to the particular needs of the investigated area and dataset specifics.

Assessment of Metal Intake by Selected Food Supplements Based on Beehive Products.

The aim of this study was to determine the quantity of particular toxic metals (Pb, Cd, As, Hg) and micronutrients (Cr, Fe, Co, Ni, Cu, Zn, Se) in the recommended daily dose of 51 food supplements based on beehive products. Samples taken from the Croatian market were submitted for the identification/quantification of studied metals and micronutrients. It was carried out by means of inductively coupled plasma mass spectrometry (ICP-MS). Eleven samples (21.57%) showed an increased concentration of total arsenic, three samples (5.88%) contained an increased concentration of total iron, and eight samples (15.68%) had an increased concentration of total nickel. Three samples (5.88%) contained an increased concentration of zinc, while one sample (1.96%) contained an increased concentration of selenium. Increased levels of certain toxic metals and micronutrients do not pose a danger to human health because the amount identified was less than what can cause toxic effects in humans. All other analysed metals and micronutrients fell within the defined literature values. Despite certain increases in particular parameters, all samples met the established toxicity criteria. This study evidenced their safety if consumed in the recommended daily dose.

Sea water whirlpool spa as a source of Legionella infection.

Bacterial pneumonia caused by the inhalation of aerosols contaminated with Legionella spp. is also known as Legionnaires' disease. In this study, we report a case of pneumonia caused by Legionella pneumophila sg.1 in a 58-year-old man who visited a sea water-filled whirlpool within a hotel and spa complex. The patient's Legionella urine antigen test was positive for L. pneumophila sg.1. During the field study, samples were taken from both the outdoor and indoor sea water-filled pools. Samples from the whirlpool were culture positive for L. pneumophila sg.1. Typing results indicated sea water isolate belonged to Sequence type ST82 and Allentown/France MAb subgroup. In vitro experiments showed that L. pneumophila strains are able to survive within sea water up to 7 days, and survival time is prolonged with sea water dilution. Also, our results indicate that L. pneumophila Allentown strain was the most resistant to adverse conditions in sea water with the highest values of DT50 (420 min) and DT90 (1,396 min). The possible source of infection was adding potable water for filling up the whirlpool. The survival of the L. pneumophila in additionally conditioned sea water should be considered in a further study.

Status of faecal pollution in ports: A basin-wide investigation in the Adriatic Sea.

Ports are subject to a variety of anthropogenic impacts, and there is mounting evidence of faecal contamination through several routes. Yet, little is known about pollution in ports by faecal indicator bacteria (FIB). FIB spatio-temporal dynamics were assessed in 12 ports of the Adriatic Sea, a semi-enclosed basin under strong anthropogenic pressure, and their relationships with environmental variables were explored to gain insight into pollution sources. FIB were abundant in ports, often more so than in adjacent areas; their abundance patterns were related to salinity, oxygen, and nutrient levels. In addition, a molecular method, quantitative (q)PCR, was used to quantify FIB. qPCR enabled faster FIB determination and water quality monitoring that culture-based methods. These data provide robust baseline evidence of faecal contamination in ports and can be used to improve the management of routine port activities (dredging and ballast water exchange), having potential to spread pathogens in the sea.

A baseline study of the metallothioneins content in digestive gland of the Norway lobster Nephrops norvegicus from Northern Adriatic Sea: Body size, season, gender and metal specific variability.

Metallothioneins content was investigated in digestive gland of two wild-caught Norway lobster Nephrops norvegicus populations from the Northern Adriatic Sea, in relation to body size, season and gender. Concomitant accumulation of cadmium, mercury, arsenic, lead, chromium and manganese, reactive oxygen species concentration and energy reserves in digestive gland were also assessed. While differences between genders were not recorded, metallothioneins content seasonal trends were affected by body size. Most of parameters displayed inconsistent trends across sampling sites. Significant correlation between metallothioneins content and cadmium, arsenic and mercury concentrations was recorded only for larger lobsters. A negative correlation of reactive oxygen species concentration and metallothioneins content was observed for small, but not large lobsters. Energy reserves, in particular lipids, could considerably influence biochemical and chemical parameters variations. The present results constitute the essential baseline for future studies aimed at evaluating the N. norvegicus health in relation to metal contamination of coastal sediments.

Temporal variations analyses and predictive modeling of microbiological seawater quality.

Bathing water quality is a major public health issue, especially for tourism-oriented regions. Currently used methods within EU allow at least a 2.2 day period for obtaining the analytical results, making outdated the information forwarded to the public. Obtained results and beach assessment are influenced by the temporal and spatial characteristics of sample collection, and numerous environmental parameters, as well as by differences of official water standards. This paper examines the temporal variation of microbiological parameters during the day, as well as the influence of the sampling hour, on decision processes in the management of the beach. Apart from the fecal indicators stipulated by the EU Bathing Water Directive (E. coli and enterococci), additional fecal (C. perfringens) and non-fecal (S. aureus and P. aeriginosa) parameters were analyzed. Moreover, the effects of applying different evaluation criteria (national, EU and U.S. EPA) to beach ranking were studied, and the most common reasons for exceeding water-quality standards were investigated. In order to upgrade routine monitoring, a predictive statistical model was developed. The highest concentrations of fecal indicators were recorded early in the morning (6 AM) due to the lack of solar radiation during the night period. When compared to enterococci, E. coli criteria appears to be more stringent for the detection of fecal pollution. In comparison to EU and U.S. EPA criteria, Croatian national evaluation criteria provide stricter public health standards. Solar radiation and precipitation were the predominant environmental parameters affecting beach water quality, and these parameters were included in the predictive model setup. Predictive models revealed great potential for the monitoring of recreational water bodies, and with further development can become a useful tool for the improvement of public health protection.

Escherichia coli in marine water: Comparison of methods for the assessment of recreational bathing water samples.

Bathing Water Directive (2006/7/EC) specifies two reference methods for Escherichia coli detection: ISO 9308-1 and 9308-3. The revised ISO 9308-1 is recommended only for waters with a low bacterial background flora. Considering the extended time needed for analysis and, generally, the lack of experience in using ISO 9308-3 in the Mediterranean, the suitability of ISO 9308-1 for the examination of E. coli in bathing water was evaluated. The present study was aimed at a comparison of data obtained by the reference method in seawater samples (110 beaches, N=477) with data received from six alternative methods. Results show that recently used TSA/TBA method may overestimate E. coli numbers in marine waters. The temperature modified ISO 9308-1 (44°C) did not significantly alter the results, but outperformed the antibiotic supplemented agar at reducing non-E. coli bacteria on the plates, allowing the use of the respective method for monitoring coastal water.

Evaluation of equivalence between different methods for enumeration of fecal indicator bacteria before and after adoption of the new Bathing Water Directive and risk assessment of pollution.

The quality of bathing water is of considerable public importance due to the possibility of fecal contamination. In 2009, Croatia implemented the new European Bathing Water Directive (BWD, 2006/7/EC) establishing stricter microbiological standards for new parameters with new reference methods. This study aims to evaluate the equivalence of different methods according to the old and revised BWD and to provide the possibility of data comparison. Furthermore, the directive requires the establishment of the bathing water profile (BWP) for pollution risk assessment. The estimation of consistency of pollution risk assessment with obtained microbiological results was also performed. Six marine beaches of the Municipality of Rijeka (Croatia) were examined during the 2009 season. Statistical analysis showed equivalence between determination methods for fecal contamination indicators. Based on the current water classification results, the need for correction of estimated pollution risks and recommendations for inclusion of historical microbiological data during BWP enactment was noticed.