Response of single benthic metrics and multi-metric methods to anthropogenic pressure gradients, in five distinct European coastal and transitional ecosystems

In recent times many benthic indices have been proposed to assess the ecological quality of marine waters worldwide. In this study we compared single metrics and multi-metric methods to assess coastal and transitional benthic status along human pressure gradients in five distinct environments across Europe: Varna bay and lake (Bulgaria), Lesina lagoon (Italy), Mondego estuary (Portugal), Basque coast (Spain) and Oslofjord (Norway). Hence, 13 single metrics (abundance, number of taxa, and several diversity and sensitivity indices) and eight of the most common indices used within the European Water Framework Directive (WFD) for benthic assessment were selected: index of size spectra (ISS), Benthic assessment tool (BAT), Norwegian quality index (NQI), Multivariate AMBI (M-AMBI), Benthic quality index (BQI), (Benthic ecosystem quality index (BEQI), Benthic index based on taxonomic sufficiency (BITS), and infaunal quality index (IQI). Within each system, sampling sites were ordered in an increasing pressure gradient according to a preliminary classification based on professional judgement. The different indices are largely consistent in their response to pressure gradient, except in some particular cases (i.e. BITS, in all cases, or ISS when a low number of individuals is present). Inconsistencies between indicator responses were most pronounced in transitional waters (i.e. IQI, BEQI), highlighting the difficulties of the generic application of indicators to all marine, estuarine and lagoonal environments. However, some of the single (i.e. ecological groups approach, diversity, richness) and multi-metric methods (i.e. BAT, M-AMBI, NQI) were able to detect such gradients both in transitional and coastal environments, being these multi-metric methods more consistent in the detection than single indices. This study highlights the importance of survey design and good reference conditions for some indicators. The agreement observed between different methodologies and their ability to detect quality trends across distinct environments constitutes a promising result for the implementation of the WFD’s monitoring plans. Moreover, these results have management implications, regarding the dangers of misclassification, uncertainty in the assessment, use of conflicting indices, and testing and validation of indices.     

Alkaline Phosphatase Activity and Utilization of Dissolved Organic Phosphorus by Algae in Subtropical Coastal Waters

Alkaline phosphatase activity (APA) and the availability of dissolved organic phosphorus (DOP) to marine algae were determined in Xiamen Bay and in algal batch culture systems. Results showed that APA changed with seasons, increasing to the highest value in summer and decreasing to the lowest in autumn and spring in Xiamen Bay. Tests on natural populations of planktonic algae and bacteria community showed that algae were mostly responsible for DOP utilization, while bacteria could not take up DOP compounds. Results from algal batch cultures also supported the above conclusion. Relationships between APA and environmental factors indicated that APA was negatively correlated with phosphorus level such as phosphate and small molecular DOP, and APA played an important role in utilization of DOP by algae. All the results emphasized the ecological significance of DOP in subtropical coastal waters.     

锂同位素地球化学在地热流体水岩反应中的应用——以川西现代富锂热泉研究为例

高温流体的化学组成及同位素特征是深部环境信息的重要载体.本文基于锂同位素地球化学方法系统分析了川西现代热泉地热流体的水化学特征、水岩反应过程、补给来源、水岩反应温度及循环深度.研究结果显示,茶洛热泉水化学相类型为HCO3-Na型,与地表水和冷地下水的HCO3-Ca型存在明显区别.利用锂同位素温标估算茶洛热泉的水岩反应体...     

Retention of mercury in sediments of the Baltic Sea near Oulu,Finland

Several cores were compared to elucidate the grade of mercury retention in sediments of the Baltic Sea near Oulu, Finland. The known history of the mercury discharge to waste water from a chlor-alkali plant, the primary pollution source, was compared to that in the sedimentary record. One core was dated by lead-210 and varve counts. During the past thirty years, the rate of sedimentation was up to 10 mm per year corresponding to a dry matter accumulation rate of about 3 kg m^–2a^–1. Under these conditions, most of the mercury reaching the sediment was retained. Correspondingly, the mercury levels in fish were considerably lower, with a delay of some five years.The present mercury content of the upper layers is some 1/4 or 1/5 that of the late 1970's, but it is still some twentyfold compared to levels at the beginning of the century. The extent to which the present mercury level in the sediment represents the various phases of industrial emission remains unsolved due to the origin of mercury in this sea area from several other sources and due to difficulties in exact core correlations from different years.     

The marine killers: Dinoflagellates in estaurine and coastal waters

Records of massive fish kills and paralytic shellfish poisoning (PSP) in Europe and North America go back to the 17th century. But, it was not until the 1940s when the relationship between PSP, red tide and toxic dinoflagellateGonyaulax was established. Recent records show that PSP and related poisons caused by toxic dinoflagellates in coastal waters and estuaries, are a world-wide problem. Diarrhetic shellfish poisoning (DSP) and neurotoxic poisoning (NSP), believed earlier as bacterial or viral infections are now shown to be caused by other toxic dinoflagellates such asDinophysis. The shellfish most often involved in the poisoning are mussels and clams. Other dinoflagellates,Gyrodinium, occasionally cause massive fish kills in vast coastal areas, resulting in fishery and economic losses.Factors promoting toxic dinoflagellate bloom development and PSP/DSP outbreaks are not fully understood. In previous studies, temperature was considered as the principal factor influencing dinoflagellate blooming. Recent studies showed that other factors such as salinity, sunlight, freshwater runoff and water stability are also important. Pollution from land drainage and sewage discharge in inshore waters were also implicated.Current knowledge indicates that although chemical and biotic factors are important forin-situ growth of dinoflagellate cells, convergence by thermal and tidal fronts is essential for cell accumulation and bloom development. Advances in physical oceanographic research, modelling and remote sensing enabled the detection of fronts and bordering eddies with high precision. There is a potential for an increased use of these technological advances in predicting and monitoring the bloom development.The present paper overviews the history and distribution of toxic dinoflagellates, and the physical factors influencing bloom development and PSP/DSP outbreaks. Future research needs to improve the predictability and control of this world-wide hazard are also discussed.     

Discovery of the Avon – Solent Fracture Zone and its relationship to Bath hot springs

 The hot springs of Bristol and Bath and two geothermal wells at Southampton are located on a 155-km-long Avon–Solent Fracture Zone extending in a NW–SE direction from the Severn Estuary to the English Channel. Initiated during the Variscan earth movements and reactivated in Miocene times, the structure, which extends across the English Channel to France, is still active. With this discovery, it should now be possible to throw fresh light on the origin and movement of the thermal water at Bath and thus to protect the hot springs from derogation by limestone quarrying. Received: 16 October 1995 · Accepted: 13 February 1996     

Evaluation of the Influence of Aquatic Plants and Lake Bottom on the Remote-Sensing Reflectance of Optically Shallow Waters

Abstract

Aquatic plants and lake bottoms in optically shallow waters (OSWs) wield great influence on reflectance spectra, resulting in the inapplicability of most existing bio-optical models for water colour remote sensing in lakes. Based on radiative transfer theory and measured spectra from a campaign for Lake Taihu in October 2008, absorption and backscattering coefficients were used to simulate the remote-sensing reflectance, which are considered to be reliable if matched to their measured counterparts. Several cases of measured spectra at different depths, Secchi disk depth transparency, and aquatic plant height and coverage were analyzed thoroughly for spectral properties. The contribution of aquatic plants was evaluated and compared with the measured and simulated remote-sensing reflectance values. This is helpful for removing the influence of aquatic plants and lake bottoms from the spectra and for constructing an improved chlorophyll a retrieval model for OSWs, such as that for Lake Taihu, China.     

Oxyanion Concentrations in Eastern Sierra Nevada Rivers – 2. Arsenic and Phosphate

Water samples were collected from the Truckee River-Pyramid Lake system, the Walker River-Walker Lake system, and the Carson River, all located in eastern California and western Nevada, U.S.A., at three different times (i.e., summer 1991, spring 1992, and autumn 1992) over a two year period. The concentrations of As, Na, Cl, PO4, and pH were measured in these river samples and the associated terminal lakes. Arsenic values ranged from below 13 nmol/kg near Truckee, California to 160 nmol/kg at Nixon, Nevada in the Truckee River, from 40 nmol/kg in the headwaters of both West and East Walker Rivers to 270 nmol/kg below Weber Reservoir on the main branch of the Walker River, and from <27 nmol/kg to 234 nmol/kg for the lower Carson River system. Arsenic concentrations in Steamboat Creek (0.91 mol/kg–1.80 mol/kg) in the Truckee River catchment are above the U.S. EPA drinking water maximum contaminant level of 0.67 mol/kg, as are the As concentrations in both Pyramid Lake (1.33 mol/kg–1.57 mol/kg ) and Walker Lake (13.7 mol/kg–18.7 mol/kg). Sources of As for all three rivers include weathering of As-rich rocks and/or regolith and input of high-As geothermal spring waters, both processes primarily, although not exclusively, adding As to the headwater regions of these rivers. Steamboat Hot Springs (29 mol/kg As 54.5 mol/kg), for example, is identified as a source of As to the Truckee River via Steamboat Creek. The high As concentrations in Pyramid and Walker Lakes are likely due to (1) desorption of arsenate from aquatic particulate matter in these high pH waters (9.0 pH 9.5), (2) limited biologic uptake of arsenate, and (3) evaporative concentration of the lake waters. Evaluation of molar PO4}/As ratios of river waters and geothermal spring waters (e.g., Steamboat Hot Springs), indicates that phosphate is substantially enriched in Steamboat Creek as well as the mid to lower reaches of the Walker and Carson Rivers. These regions of each river are dominated by agricultural interests and, additionally, in the case of Steamboat Creek, residential areas and golf courses. Our data strongly imply that phosphate-rich agricultural return flow has likely added P to these streams and, consequently, increased their respective P:As ratios.     

Conceptual hydrodynamic-thermal mapping modelling for coral reefs at south Singapore sea

Coral reefs are important ecosystems that not only provide shelter and breeding ground for many marine species, but can also control of carbon dioxide level in ocean and act as coastal protection mechanism. Reduction of coral reefs at Singapore coastal waters (SCW) region remains as an important study to identify the environmental impact from its busy industrial activities especially at the surrounding of Jurong Island in the south. This kind of study at SCW was often being related to issues such as turbidity, sedimentation, pollutant transport (from industry activities) effects in literatures, but seldom investigated from the thermal change aspect. In this paper, a computational model was constructed using the Delft3D hydrodynamic module to produce wave simulations on sea regions surrounding Singapore Island. The complicated semi-diurnal and diurnal tidal wave events experienced by SCW were simulated for 2 weeks duration and compared to the Admiralty measured data. To simulate the thermal mapping at the south Singapore coastal waters (SSCW) region, we first adapted a conversion of industrial to thermal discharge; then from the discharge affected area a thermal map was further computed to compare with the measured coral map. The outcomes show that the proposed novel thermal modelling approach has quite precisely simulated the coral map at SSCW, with the condition that the near-field thermal sources are considered (with the coverage area in the limit of 20 km × 20 km).