Assessment of water quality with emphasis on trophic status in bathing areas from the central-southern coast of Cuba

Bathing water quality has become a matter of concern due to health risks. This study sought to assess water quality in bathing areas from the southeastern coast of the Cienfuegos province, Cuba. Certain physical, chemical, and biological parameters (salinity, temperature, pH, oxygen saturation, N-NH4+, N-NO2-, N-NO3-, P-PO43-, COD, BOD5, fats and oils, chlorophyll-a, thermotolerant and total coliforms, and phytoplankton) were measured on five beaches during 2019-2020 in both rainy and dry seasons. A water quality index (WQI) was calculated using the the results of an eutrophication index (EI) and subsequently analyzed. Cluster analysis (CA) and principal components analysis (PCA) were conducted to interpret water quality variations. The WQI values ranged between fair and good, with significant differences between seasons. Multivariate analyses demonstrated the influence of river contributions on water quality indicators based on the results of the CA and the first principal component (PC1) correlated with Sal, DO, total and thermotolerant coliforms, and certain nutrients. PCA also reflected the increase in BOD5 levels during the summer based on PC2, while the PC3 correlated with COD and response parameters (chlorophyll-a and phytoplankton) were linked to the trophic status. The assessment of trophic status showed non-eutrophic conditions. The abundance and diversity of phytoplankton in these beaches was low (128.5 x 103 cells L-1, total mean value), following the normative definitions of the water framework directive. Harmful algal species occurred in low numbers (1.88 x 103 cells L-1, total mean value), but certain species could represent a risk of dermatitis to bathers. The application of different classification schemes allowed for a comprehensive assessment of water quality in this coastal zone, helping to identify the need for monitoring and further ecological study on harmful algae species

210Pb and 137Cs as tracers of recent sedimentary processes in two water reservoirs in Cuba.

Hanabanilla and Paso Bonito Reservoirs are the main fresh water sources for about half a million inhabitants in central Cuba. Prior to this investigation precise information about the losses of storage capacity was not available. Sedimentation is the dominant process leading to reduction in water storage capacity. We investigated the sedimentation process in both reservoirs by analyzing environmental radionuclides (e.g. 210Pb, 226Ra and 137Cs) in sediment cores. In the shallow Paso Bonito Reservoir (mean depth of 6.5 m; water volume of 8 x 106 m3), we estimated a mean mass accumulation rate (MAR) of 0.4 ± 0.1 g cm-2y-1 based on 210Pb chronologies. 137Cs was detected in the sediments, but due to the recent construction of this reservoir (1975), it was not possible to use it to validate the 210Pb chronologies. The estimated MAR in this reservoir is higher than the typical values reported in similar shallow fresh water reservoirs worldwide. Our results highlight a significant loss of water storage capacity during the past 30 years. In the deeper and larger Hanabanilla Reservoir (mean depth of 15.5 m; water volume of 292 x 106 m3), the MAR was investigated in three different sites of the reservoir. The mean MARs based on the 210Pb chronologies varied between 0.15 and 0.24 g cm -2y-1. The MARs calculated based on the 137Cs profiles further validated these values. We show that the sediment accumulation did not change significantly over the last 50 years. A simple empirical mixing and sedimentation model that assumes 137Cs in the water originated from both, direct atmospheric fallout and the catchment area, was applied to interpret the 137Cs depth profiles. The model consistently reproduced the measured 137Cs profiles in the three cores (R2 \u3e 0.9). Mean residence times for 137Cs in the water and in the catchment area of 1 y and 35-50 y, respectively were estimated. The model identified areas where the catchment component was higher, zones with higher erosion in the catchment, and sites where the fallout component was quantitatively recorded in the sediments

210Pb and 137Cs as tracers of recent sedimentary processes in two water reservoirs in Cuba.

Hanabanilla and Paso Bonito Reservoirs are the main fresh water sources for about half a million inhabitants in central Cuba. Prior to this investigation precise information about the losses of storage capacity was not available. Sedimentation is the dominant process leading to reduction in water storage capacity. We investigated the sedimentation process in both reservoirs by analyzing environmental radionuclides (e.g. 210Pb, 226Ra and 137Cs) in sediment cores. In the shallow Paso Bonito Reservoir (mean depth of 6.5 m; water volume of 8 x 106 m3), we estimated a mean mass accumulation rate (MAR) of 0.4 ± 0.1 g cm-2y-1 based on 210Pb chronologies. 137Cs was detected in the sediments, but due to the recent construction of this reservoir (1975), it was not possible to use it to validate the 210Pb chronologies. The estimated MAR in this reservoir is higher than the typical values reported in similar shallow fresh water reservoirs worldwide. Our results highlight a significant loss of water storage capacity during the past 30 years. In the deeper and larger Hanabanilla Reservoir (mean depth of 15.5 m; water volume of 292 x 106 m3), the MAR was investigated in three different sites of the reservoir. The mean MARs based on the 210Pb chronologies varied between 0.15 and 0.24 g cm -2y-1. The MARs calculated based on the 137Cs profiles further validated these values. We show that the sediment accumulation did not change significantly over the last 50 years. A simple empirical mixing and sedimentation model that assumes 137Cs in the water originated from both, direct atmospheric fallout and the catchment area, was applied to interpret the 137Cs depth profiles. The model consistently reproduced the measured 137Cs profiles in the three cores (R2 \u3e 0.9). Mean residence times for 137Cs in the water and in the catchment area of 1 y and 35-50 y, respectively were estimated. The model identified areas where the catchment component was higher, zones with higher erosion in the catchment, and sites where the fallout component was quantitatively recorded in the sediments

Summer bloom of Vulcanodinium rugosum in Cienfuegos Bay (Cuba) associated to dermatitis in swimmers

The marine dinoflagellate Vulcanodinium rugosum produces powerful paralyzing and cytotoxic compounds named pinnatoxins (PnTX) and portimines. Even though, no related human intoxication episodes following direct exposure in seawater or the ingestion of contaminated seafood have been documented so far. This study aimed at investigating a dinoflagellate bloom linked to acute dermatitis cases in two recreational beaches in Cienfuegos Bay, Cuba. We used epidemiological and clinical data from 60 dermatitis cases consisting of individuals in close contact with the bloom. Seawater physical-chemical properties were described, and the microorganism causing the bloom was identified by means of light and scanning electron microscopy. Morphological identification was confirmed genetically by sequencing the internal transcribed spacers ITS1 and ITS2, and the 5.8S rDNA region. Toxic compounds were identified from a bloom extract using liquid chromatography (LC) coupled to high-resolution mass spectrometry (HRMS), and their concentrations were estimated based on low-resolution tandem mass spectrometry (LC-MS/MS). Sixty people who had prolonged contact with the dinoflagellate bloom suffered acute dermal irritation. Most patients (79.2%) were children and had to be treated with antibiotics; some required >5-day hospitalization. Combined morphological and genetic characters indicated V. rugosum as the causative agent of the bloom. rDNA sequences of the V. rugosum genotype found in the bloom aligned with others from Asia, including material found in the ballast tank of a ship in Florida. The predominant toxins in the bloom were portimine, PnTX-F and PnTX-E, similar to strains originating from the Pacific Ocean. This bloom was associated with unusual weather conditions such as frequent and prolonged droughts. Our findings indicate a close link between the V. rugosum bloom and a dermatitis outbreak among swimmers in Cienfuegos Bay. Phylogenetic evidence suggests a recent introduction of V. rugosum from the Pacific Ocean into Caribbean waters, possibly via ballast water