Mesozooplankton assemblages and their relationship with environmental variables: a study case in a disturbed bay (Beagle Channel,Argentina)

This study focused on the seasonal and spatial analysis of the mesozooplankton community in a human-impacted subantarctic bay in Argentina and aimed to detect assemblages associated with environmental variability. Mesozooplankton samples and environmental data were obtained in the Ushuaia Bay (UB) seasonally, from August 2004 to June 2005, and spatially, from coastal (more polluted), middle (less influenced) and open sea water (free polluted) sampling stations. Remarkable seasonal changes on the mesozooplankton community were observed. Nitrogenated nutrients, chlorophyll a, salinity and temperature were the prevailing environmental conditions likely associated with the different mesozooplankton assemblages found in the bay. The copepods Eurytemora americana, Acartia tonsa, Podon leuckarti and Nematoda were particularly observed on the northwest coast of the bay, characterized by the highest level of urban pollution, eutrophicated by sewage and freshwater inputs from the Encerrada Bay which is connected to it. The stations situated in the northeast area, mostly influenced by freshwater input from rivers and glacier melting, showed low mesozooplankton abundances and an important contribution of adventitious plankton. The copepods Ctenocalanus citer, Clausocalanus brevipes and Drepanopus forcipatus were mostly observed at the stations located near the Beagle Channel, characterized by open sea and free polluted waters. Our findings suggest that the variations observed in the mesozooplankton assemblages in the UB seem to be modulated by environmental variables associated with the anthropogenic influence, clearly detected on the coast of the bay. Certain opportunistic species such as A. tonsa and E. americana could be postulated as potential bioindicators of water quality in subantarctic coastal ecosystems.     

2012—2017年海州湾潮间带大型底栖动物群落结构及变化

为了解海州湾潮间带大型底栖动物群落结构，分析人类养殖活动对其影响，于2012-2017年对该区域大型底栖动物进行调查。结果表明：6年间共发现120种大型底栖动物，依据种类组成进行聚类分析可分为4组；调查中总平均丰度为3 495.9 ind./m²，范围为506.7~17 864.0 ind./m²；总平均生物量为197.26 g/m²，范围为1.58~489.17 g/m²。光滑河蓝蛤（Potamocorbula laevis）为第一优势种，其繁殖盛期在每年9-10月。调查期间生物多样性整体呈下降趋势，人类的养殖活动主导着海州湾潮间带大型底栖动物群落结构的变化。     

Long-term monitoring of the impact of a capture-based bluefin tuna aquaculture on water column nutrient levels in the Eastern Aegean Sea, Turkey

Capture-based aquaculture of Atlantic bluefin tuna in the Mediterranean has been expanding rapidly but little is known about its environmental impact. In order to understand the consequences of this new sector, long-term monitoring is needed. For this purpose, we investigated the impact of a capture-based tuna farm located in the Gerence Bay (Aegean Sea) on the water column on a seasonal basis from 2005 to 2008, where in the water column, temperature, salinity, pH, dissolved oxygen, nutrients (nitrite, nitrate, ammonium, and phosphate), and chlorophyll a, in the sediment organic carbon variables were measured. Although highest nutrient concentrations were observed at the cage station as compared to the two controls in the production period, differences were not statistically significant between stations. Monitoring of physico-chemical parameters, nutrients, and chlorophyll a in water column together with organic carbon in sediment did not show detectable impact of fattening of Atlantic bluefin tuna. This was probably caused by strong currents present in the area, location of the cages away from the coast, hence high water depth, controlled feeding, and periodic presence of tuna farming activity in the study area.     

Copper mine tailing disposal in northern Chile rocky shores: Enteromorpha compressa (Chlorophyta) as a sentinel species

The study assesses the ecological impact caused by the El Salvador untreated (1975–1990) and treated (1991–1994) copper mine tailings on rocky intertidal communities in and around the dumping site at Caleta Palito, northern Chile. Ecological changes are monitored for 16 years in polluted and unpolluted sites within a geographical area of 90 km. Copper concentration levels in water and the intertidal Chlorophyta E. compressa are presented. The results confirm a notorious reduction in the number of species and significant differences between polluted and unpolluted intertidal communities. At polluted sites, following the initiation of the disposal, all species of invertebrates and algae disappeared and primary space (rock) was partially or completely dominated by E. compressa along more than a decade. Its persistence in these sites supports the view that this taxon is a sentinel species resisting high levels of copper pollution. During the past four years, following the steps given to treat the tailings, at polluted sites there are preliminary indications showing increases in the number of species of algae and invertebrate. The need for future monitoring to elucidate ecosystem restoration processes is discussed.     

Assessing the ecological effects of human impacts on coral reefs in Bocas del Toro,Panama

Environmental and biological reef monitoring was conducted in Almirante Bay (Bahía Almirante) in Bocas del Toro, Panama, to assess impacts from anthropogenic developments. An integrated monitoring investigated how seasonal temperature stress, turbidity, eutrophication and physical impacts threatened reef health and biodiversity throughout the region. Environmental parameters such as total suspended solids [TSS], carbon isotopes (δ¹³C), C/N ratios, chlorophyll a, irradiance, secchi depth, size fractions of the sediments and isotope composition of dissolved inorganic carbon [DIC] of the water were measured throughout the years 2010 and 2011 and were analysed in order to identify different impact sources. Compared to data from Collin et al. (Smithsonian Contributions to the Marine Sciences 38:324–334, 2009) chlorophyll a has doubled at sites close to the city and the port Almirante (from 0.46–0.49 to 0.78–0.97 μg l^?1) and suspension load increased, visible by a decrease in secchi depth values. Visibility decreased from 9-13 m down to 4 m at the bay inlet Boca del Drago, which is strongly exposed to river run off and dredging for the shipping traffic. Eutrophication and turbidity levels seemed to be the determining factor for the loss of hard coral diversity, most significant at chlorophyll a levels higher than 0.5 μg l^?1 and TSS levels higher than 4.7 mg l^?1. Hard coral cover within the bay has also declined, at some sites down to <10 % with extremely low diversities (7 hard coral species). The hard coral species Porites furcata dominated the reefs in highly impacted areas and showed a strong recovery after bleaching and a higher tolerance to turbidity and eutrophication compared to other hard coral species in the bay. Serious overfishing was detected in the region by a lack of adult and carnivorous fish species, such as grunts, snappers and groupers. Study sites less impacted by anthropogenic activities and/or those with local protection showed a higher hard coral cover and fish abundance; however, an overall loss of hard coral diversity was observed.     

Characterization of microbial communities from coastal waters using microarrays

Molecular methods, including DNA probes, were used to identify and enumerate pathogenic Vibrio species in the Chesapeake Bay; our data indicated that Vibrio vulnificus exhibits seasonal fluctuations in number. Our work included a characterization of total microbial communities from the Bay; development of microarrays that identify and quantify the diversity of those communities; and observation of temporal changes in those communities. To identify members of the microbial community, we amplified the 16S rDNA gene from community DNA isolated from a biofilm sample collected from the Chesapeake Bay in February, 2000. The resultant 75 sequences were 95% or more similar to 7 species including two recently described Shewanella species, baltica and frigidimarina, that have not been previously isolated from the Chesapeake. When the genera of bacteria from biofilm after culturing are compared to those detected by subcloning amplified 16S fragments from community DNA, the cultured sample exhibited a strong bias. In oysters collected in February, the most common bacteria were previously unknown. Based on our 16S findings, we are developing microarrays to detect these and other microbial species in these estuarine communities. The microarrays will detect each species using four distinct loci, with the multiple loci serving as an internal control. The accuracy of the microarray will be measured using sentinel species such as Aeromonas species, Escherichia coli, and Vibrio vulnificus. Using microarrays, it should be possible to determine the annual fluctuations of bacterial species (culturable and non-culturable, pathogenic and non-pathogenic). The data may be applied to understanding patterns of environmental change; assessing the health of the Bay; and evaluating the risk of human illness associated with exposure to and ingestion of water and shellfish.     

Cyanobacterial Flora from Polluted Industrial Effluents

Effluents originating from pesticides, agro-chemicals, textile dyes and dyestuffs industries are always associated with high turbidity, colour, nutrient load, and heavy metals, toxic and persistent compounds. But even with such an anthropogenic nature, these effluents contain dynamic cyanobacterial communities. Documentation of cyanobacterial cultures along the water channels of effluents discharged by above mentioned industries along the west coast of India and their relationship with water quality is reported in this study. Intensity of pollution was evaluated by physico-chemical analysis of water. Higher load of solids, carbon and nutrients were found to be persistent throughout the analysis. Sediment and water samples were found to be colored in nature. Cyanobacterial community structure was found to be influenced by the anthropogenic pollution. 40 different cyanobacterial species were recorded from 14 genera of 5 families and an elevated occurrence of Phormidium, Oscillatoria and Chroococcus genera was observed in all the sampling sites.     

The 210Po and 210Pb levels in surface sediment samples in the Izmir Bay (Aegean Sea-Turkey)

Bottom sediments reflect in general the relative contamination of a sea area. Therefore, a great deal of monitoring work has been dedicated to the analysis of bottom sediments. Izmir Bay is a very important pollution centre in Turkish Aegean coast region due to a densely populated community, industrial complex and maritime transportation, and there are many streams flowing into the bay that pass through a number of industrial and agricultural areas. It had received the majority of domestic and industrial wastewaters until the wastewater treatment plant was constructed. It is well known that sediments play an important role as reservoirs of a fraction of the pollution in aquatic systems. Therefore, sediment samples were collected monthly from three stations which are located in the inner part of the bay during the period January to December 2003. Temporal variations and seasonal changes on their ²¹⁰Po and ²¹⁰Pb contents were examined, and the activity concentrations of ²¹⁰Po and ²¹⁰Pb were found to vary from 43±6 to 132±12 and 27±5 to 91±9 Bq kg^???1 dry wt, respectively. The highest values of those natural radionuclides were measured at Kar??yaka Station because of the current systems of the bay. Seasonally, the ²¹⁰Pb levels were found to increase during the winter time for all the stations.     

Spatial Analysis of Volatile Organic Compounds from a Community-Based Air Toxics Monitoring Network in Deer Park,Texas, USA

In the summer of 2003, ambient air concentrations of volatile organic compounds (VOCs) were measured at 12 sites within a 3-km radius in Deer Park, Texas near Houston. The purpose of the study was to assess local spatial influence of traffic and other urban sources and was part of a larger investigation of VOC spatial and temporal heterogeneity influences in selected areas of Houston. Seventy 2-h samples were collected using passive organic vapor monitors. Most measurements of 13 VOC species were greater than the method detection limits. Samplers were located at 10 residential sites, a regulatory air monitoring station, and a site located at the centroid of the census tract in which the regulatory station was located. For residential sites, sampler placement locations (e. g., covered porch vs. house eaves) had no effect on concentration with the exception of methyl tertiary-butyl ether (MTBE). Relatively high correlations (Pearson r > 0.8) were found between toluene, ethylbenzene, and o,m,p-xylenes suggesting petroleum-related influence. Chloroform was not correlated with these species or benzene (Pearson r < 0.35) suggesting a different source influence, possibly from process-related activities. As shown in other spatial studies, wind direction relative to source location had an effect on VOC concentrations.