Sustainable catchment restoration for reintroduction of captive bred freshwater pearl mussels Margaritifera margaritifera

The Ballinderry River, Co. Tyrone (SAC), is one of only six rivers in Northern Ireland that still supports a population of the globally endangered freshwater pearl mussel, Margaritifera margaritifera. Fewer than 1000 individuals still exist in the river; without intervention it is predicted the Ballinderry pearl mussel will be extinct by 2098. This paper aims to identify key catchment pressures on remaining mussel stocks and prioritise tributaries within the catchment for remediation work to ensure effective targeting of limited resources. A combination of redox assessment, river surveys and SCIMAP modelling was used to rank tributaries, taking into consideration their size and proximity to the main mussel population at the “sanctuary site”. Diffuse and point sources of sediment were identified within the prioritised catchment. The Tulnacross tributary was selected as the highest priority tributary and has been used in a pilot remediation study. A number of different hard and soft engineering techniques have been used for remediation as well as replacing cattle drinkers with pasture pumps and fencing alongside the river. Initial observations suggest river substrate is cleaner. This study is an example of how to tackle problems within a large-scale catchment with limited resources with participation of local stakeholders and riparian landowners.     

River bed stability versus clogged interstitial: Depth-dependent accumulation of substances in freshwater pearl mussel (Margaritifera margaritifera L.) habitats in Austrian streams as a function of hydromorphological parameters

Substrate conditions are considered crucial for the survival of juvenile freshwater pearl mussels (Margaritifera margaritifera L.) – and therefore for the recovery of overaged populations in danger of extinction – as fine sediments can clog the interstitial habitat and hamper water and oxygen circulation to the juveniles. Watercourses and their bed sediments must meet two seemingly diametrically opposite requirements in order to offer the freshwater pearl mussel appropriate habitats: stable substrates for all live stages and an unclogged interstitial for the juveniles. As only few scientific publications deal with subsurface conditions in pearl mussel brooks, the present preliminary study tries to contribute to this topic by compiling a variety of chemical and hydromorphological data from several Austrian watercourses with distinctly different characteristics. It was clearly shown that discharge patterns, hydraulic pressure, water depths and flow velocities affect both river bed stability and the perfusion of the hyporheic zone: In an artificial millrace with permanent low flow conditions and a permanently stable substrate a distinct barrier was detected within the first 5 cm substrate depth that totally blocks the interchange between surface and interstitial water, resulting in an accumulation of substances of all kinds, among them potentially toxic substances. Such a barrier was also found to be building up in several natural watercourses, clearly indicating the danger of adverse land-use and of long-term low flow conditions in smaller brooks (given that the local decrease in precipitation, proven in long-term studies, proceeds). Significant differences in substrate concentrations in the interstitial water were detected between watercourses, whereas chemical conditions in the surface water exhibited no differences at all. An accompanying biomonitoring study showed high survival rates all over the study area, indicating the suitability of juvenile freshwater pearl mussels as bioindicators in terms of surface water, but not of interstitial water.     

Conservation of the freshwater pearl mussel (Margaritifera margaritifera) in the river Rede,UK: Identification of instream indicators for catchment-scale issues

The freshwater pearl mussel (Margaritifera margaritifera) is declining throughout its entire range. On the river Rede, North-East England, the population has been equally declining and shows no apparent recruitment. The study presented here aimed at characterizing water quality and habitat conditions for pearl mussels to identify possible indicators of pressures on the population and inform a restoration and conservation strategy. Water quality monitoring revealed levels of turbidity and suspended sediments to be above the limit set for functional pearl mussel rivers. Substrate sampling revealed silt was present at all sites. A loss of redox potential between the water column and the substrate occurred at all sites, indicating non suitable conditions for juvenile pearl mussels. These investigations suggest that fine sediment input in the river could be one of the factors preventing the development and survival of juvenile mussels while adults face water quality largely affected by high turbidity and high phosphate load. Restoration strategy for the Rede pearl mussel population should focus mainly on limiting sediment and nutrient input in the river throughout the catchment in order to improve habitat for juvenile pearl mussels. This work highlights the need for a catchment-based approach in order to succeed in the conservation of a fragile species.     

鄱阳湖流域蚌类环境DNA宏条形码引物的筛选验证

环境DNA技术是一种非侵入、高灵敏、高效率且对环境无破坏性,对生物体无损伤的调查工具.为了筛选适合于蚌类环境DNA生物多样性研究的宏条形码引物,本研究通过对鄱阳湖流域24种常见蚌的基因组DNA进行普通扩增和高通量测序筛选了11对引物(设计了9对通用引物及从相关文献中引用了2对引物),结果显示引物cytb和16S rRN...     

The occurrence and distribution of freshwater snails in a heavily industrialised region of Poland (Upper Silesia)

Anthropogenic water bodies namely fish ponds, clay pits, sand pits, dam reservoirs or mining subsidence pools are the characteristic feature of Upper Silesian landscape. In the study, the gastropod communities occurring in 296 anthropogenic water bodies were discussed in relation to their distribution in macroregions of Upper Silesia, role in industrialised and urbanised environment and the significance for regional biodiversity.In period 1998–2002, 31 freshwater gastropod species were found in the study area. It is noteworthy, that the anthropogenic water habitats of Upper Silesia provide a refuge for several rare and vulnerable species, among them e.g. Anisus leucostoma (Millet, 1813), Gyraulus rossmaessleri (V. Auerswald, 1852) and Hippeutis complanatus (Linnaeus, 1758).     

青虾生长规律与群体组成的研究

报道了上海川沙县孙桥河道青虾的生长呈明显的阶段性,如雄虾的第一阶段（1990年6—11月）的生长方程为L_t=3.38[1-e~(-0.4943(t+0.1674)];第二阶段（1991年2—6月）的生长方程为L_t=6.57/(1+e~(2.1805-0.2787t);它们的拐点分别为2.07月龄和11.97月龄。渔获群体分析结果表明,月龄为0-15月,体长范围为1.30—6.58cm,体重范围为0.060—13.39g;一年出现两个群体,其中夏季群体生活期从当年7月至翌年10月,数量大,占群体数量80％以上;秋季群体生活期从当年9月至翌年12月,约占群体数量20％左右。群体中一般雄虾数量多于雌虾数量,月性比(?)在0.61—1.35之间变动。     

基于淡水蚌类的生物学特征预测种群局部定居率和灭绝率--以鄱阳湖为例

淡水蚌类是全球最受威胁的动物群之一.加强淡水蚌类灭绝机制的研究,对促进野生淡水蚌类生物多样性的保护和管理具有重要的意义.淡水蚌类具有独特的生活史,发育过程中的钩介幼虫必须依赖于宿主鱼才能完成变态发育.淡水蚌局部种群之间的交流是通过宿主鱼的迁移和幼虫漂流来实现的.通过对鄱阳湖12个采样地点调查,计算了39种淡水蚌的局部定居率和灭绝率,利用一般线性模型,通过比较最低赤池信息准则和许瓦兹贝叶斯准则来评估淡水蚌类的8个生物学特征对预测种群局部定居率和灭绝率的可行性.结果表明:淡水蚌类的生物学特征与局部定居率和灭绝率存在相关性,可以用来预测种群局部定居和灭绝,其中种群结构和繁殖时期这两个生物学特征是预测局部定居率的最佳组合模型,分布密度、繁殖能力、保护现状和运动能力是预测局部灭绝率的最佳结合模型.就鄱阳湖淡水蚌类而言,局部灭绝率显著超过局部定居率,表明局部种群隔离程度正在加重,面临着严重的种群灭绝危机.     

Influence of plankton concentration on gametogenesis and spawning of the black lip pearl oyster Pinctada margaritifera in Ahe atoll lagoon (Tuamotu archipelago, French polynesia)

Pearl culture industry represents one of the dominant business sector of French Polynesia. However, it still entirely relies on unpredictable spat collection success. Our aim was to assess the influence of natural plankton concentration fluctuations on maturation and spawning of the black lip pearl oyster Pinctada margaritifera, during a 4months survey conducted in Ahe atoll lagoon. Plankton concentration was assessed by chlorophyll a extraction and by microscope counts while gonadic index, gonado-visceral dry weights and histology were used to measure pearl oysters reproduction activity. We found that (i) plankton concentration fluctuations were mainly related to wind regime, (ii) gametogenesis rate was mainly related to plankton concentration, (iii) spawning occurred when maximal gonad storage was reached, (iv) plankton concentration was the main spawning synchronizing factor. These results contribute explaining P. margaritifera spat collection variability in French Polynesian atoll lagoon.     

Effect of eutrophication on species composition and growth of freshwater mussels(Mollusca,Unionidae) in Lake Hallwil (Aargau,Switzerland)

Species composition, relative abundance and life history of unionid mussels are compared between 1982–86 and 1915–19 in Lake Hallwil and the outflowing brook. The recent samples of unionid mussels were collected by divers, whereas the older ones were from a shell collection. The motivation for the comparison was that the trophic degree of the lake has changed since the beginning of the century from mesotrophic to highly eutrophic. The effects of this increased trophic degree of the lake on the life cycle of unionid mussels is discussed. Predictions are made about species composition and life history in the context of the ongoing lake restoration by the authorities.     

Influence of slight differences in environmental conditions (light, hydrodynamics) on the structure and function of periphyton

Small streams are ecosystems mainly controlled by physical factors. Minor differences in these factors can affect periphyton, which are key functional communities in these ecosystems. Eight different environmental conditions combining two types of current, two flow velocities and two light intensities were produced and controlled in artificial channels. Their impact on young and mature periphyton was investigated during a 6-week exposure period. The two different levels of light intensity produced early effects on the algal community. In young periphyton, the lower level of light intensity enhanced the number of algal cells, and this community appeared to be significantly structured by light. As the periphyton matured, the effects of physical factors became more marked. At this later stage, both the bacterial and algal communities began to be affected. Both function (primary production) and structure began to respond to differences in light and in flow velocity. Small differences in low-level environmental factors, such as light and flow, had an effect both on the structure of periphyton and its functional capacities. Keeping in mind the close link between diversity and function in microbial communities, periphyton confronted to various environmental stresses (pollution, flooding) in the field may behave differently due to minor differences in physical factors.     

Interactive effects of environmental variability and human impacts on the long-term dynamics of an Amazonian floodplain lake and a South Atlantic coastal lagoon

Human activities are exposing freshwater ecosystems to a wide range of stressors, whose direct and indirect effects can be alleviated or exacerbated through interactive effects with dynamic environmental drivers. This study used long-term data from two Neotropical lacustrine freshwater systems (Batata Lake, an Amazonian floodplain lake and Imboassica lagoon, an Atlantic coastal lagoon) subjected to different kinds of environmental fluctuations (i.e., flood pulse and sandbar opening) and anthropogenic impacts (i.e., siltation and eutrophication). Our objective was to determine whether the effects of human perturbations are contingent on modifications of important biotic and abiotic characteristics through environmental variability. For both ecosystems, environmental variability consistently interacted with anthropogenic perturbations to alter most of the variables analyzed, such as nutrient dynamics, chlorophyll-a concentration, zooplankton and benthic invertebrate species richness, and temporal community stability, which indicates that interactive effects between environmental variability and anthropogenic perturbations may impact a myriad of ecosystem properties. Furthermore, the nature of these interactive effects was highly dependent on the variable considered and on the ecosystem analyzed. For example, at Imboassica lagoon, sandbar openings interacted synergistically with trophic state to increase the phosphorus concentration in the water column. At Batata Lake, flooding generally alleviated the negative effects of siltation on species richness by both diluting inorganic suspended material concentration and by promoting local recruitment from the regional species pool. Such results indicate that our ability to understand and predict the outcome of anthropogenic impacts on inland aquatic systems can be hampered if we consider human stressors as “static” phenomena disconnected from dynamic interactions with major local environmental drivers.     

Towards a long-term monitoring of Central European water mite faunas (Acari: Hydrachnidia and Halacaridae) – considerations on the background of data from 1900 to 2000

The state of knowledge of the Central European water mite fauna and the research history are briefly surveyed. Several areas for which we are provided with rich data sets are of high value for the monitoring of faunistic trends on the background of local and global environmental change. The need for a database combining historical and actual faunistic information is stressed. It should facilitate the access to all data from former times, give a survey on actual activities by regular updates, and help for a better organization of future research activities. On the base of an update of the Limnofauna Europaea (K.O. Viets 1978, Gerecke in www.watermite.org) a first attempt is made to (1) recognize changes in the Central European fauna during the past 100 years; (2) emphasize species which may be endangered or have disappeared during the past 100 years. At the present state of knowledge, the degree of threat to water mite species in this area is best calculated from their preference for particular habitat types which are rare and in danger to disappear in cultivated landscapes. Our knowledge concerning neozoic water mites in the study area is discussed.     

北京两个水库的桃花水母及其发生条件初探

为鉴定北京怀柔水库和黄松峪水库发生的桃花水母并检验其水环境质量相关性,对2022年9月9日和10日采自2个水库的桃花水母进行形态学和遗传结构分析,并结合常规水生态监测数据,初步探究桃花水母发生的水环境条件。结果显示,怀柔水库和黄松峪水库桃花水母形态结构较为相似,依据其伞径、触手数目、主辐触手长于其它触手、管状平衡囊数、刺丝囊疣圆锥状环状排列及囊状性腺等形态特征初步鉴定为索氏桃花水母和嘉定桃花水母。ITS序列分析结果显示怀柔水库样本与索氏桃花水母遗传相似性100%,黄松峪水库样本与嘉定桃花水母遗传相似性100%,佐证了形态学鉴定结果。2个水库桃花水母发生前后库区pH、溶解氧、总氮和总磷浓度以及生化需氧量等因子无明显差异,而水温和食源浮游动物生物量变动明显,水质处于中营养-轻度富营养状态。9月上旬,2个水库水温快速下降到25℃以下,而适口食源浮游动物生物量增长至1.2 mg/L以上。推断:1)桃花水母环境耐受力较强,偏爱食物丰富的中营养水体;2)水温骤变(骤升或骤降)和适口食物充裕可能是刺激桃花水母启动有性生殖的重要生态因子。据此分析了温变胁迫和营养限制对桃花水母发生的可能驱动效应,以期为...     

Influence of oyster culture practices and environmental conditions on the ecological status of intertidal mudflats in the Pertuis Charentais (SW France): a multi-index approach

The ecological quality status (EcoQ) of intertidal mudflats constrained by Pacific oyster farming was assessed by single (H’, AMBI, BENTIX and BOPA) and multimetric (M-AMBI and average score) index approaches in the Pertuis Charentais (SW France). Fifteen sampling stations were monitored seasonally for sedimentological features and macrozoobenthos in 2004. Sediments affected by oyster biodeposits showed organic matter enrichment, and sediments from off-bottom culture sites had higher organic matter contents and lower redox potentials than sediments from on-bottom culture sites. Biotic indices consistently registered responses of macrozoobenthos to organic enrichment but there was only partial agreement between single index-derived EcoQs. The average score was better than M-AMBI and single indices for determining EcoQs. Accordingly, oyster farming alters intertidal macrozoobenthic assemblages moderately, and off-bottom cultures cause more disturbance than on-bottom cultures. Hydrodynamics and seasons may interact with culture practices in smothering/strengthening biodeposition-mediated effects through dispersal/accumulation of biodeposits.     

Measurement of environmental trace-metal levels with transplanted mussels and diffusive gradients in thin films (DGT): a comparison of techniques

Transplanted mussels and diffusive gradients in thin films (DGT) were used to assess levels of cadmium, copper, lead and zinc at four sites situated inside and outside of two enclosed marinas, near Melbourne, Australia. Mussels accumulated all metals except cadmium. Over one year, there were large temporal differences in tissue metal levels in mussels, but differences between sites were only apparent for copper and lead. DGT showed temporal differences of the same kind as those seen in the mussels, but appeared to have more power to discriminate between sites. DGT found higher copper levels inside marinas than outside, and high levels of zinc were found inside one marina. Levels of copper and zinc were high enough to be of environmental concern for one site. The effect of fouling on DGT measurements will have to be quantified, or avoided by the use of multiple short-term exposures, if the technique is to become a widespread in situ monitoring tool.     

Fine sediment deposition affects biodiversity and density of benthic macroinvertebrates: A case study in the freshwater pearl mussel river Waldaist (Upper Austria)

Fine sediment deposition in stream beds frequently generated by certain land use practices has become an increasing stressor for rivers throughout the world. In this study, the role of fine sediment deposition and its impact on the benthic macro-invertebrate assemblages was investigated in a low mountain freshwater pearl mussel stream, the Waldaist. Communities of unaffected sites and sites under high fine sediment deposition were compared. Distinct reactions of benthic assemblages in fine gravelly habitats were ascertained demonstrating a severe but still underestimated threat for invertebrate biodiversity.     

深水型水库环保疏浚对水质的影响及敏感参数研究——以通济桥水库为例

国内对于作为饮用水水源地并具有水温分层特征的深水型水库环保疏浚,缺乏长期实测评价工程前后水质变化规律以及易于发生变化的水质参数的实例.因此,对于这种类型的环保疏浚,如何进行效果评价并在工程实施中控制敏感参数成为一个没有解决的问题.本文以典型的饮用水水源地、深水型的通济桥水库为对象,通过长期水质监测,研究了环保疏浚的影响.结果发现环保疏浚对总氮（TN）削减起到较好的效果,但是疏浚期间总磷（TP）浓度明显上升,完工半年后TP浓度仍略高于往年同期水平.其中,坝前库区TN浓度降低至疏浚前多年同期均值的56%~87%,而TP浓度却为疏浚前的1.87倍以上.并发现浊度、TN、TP和锰（Mn）对于环保疏浚敏感响应.其中,TP波动与底泥扰动引起的浊度变化有密切的关系;坝前库区疏浚新生底泥Mn含量较高（1251.25 mg/kg）,夏季水温分层加剧了库底水体的厌氧状态,是Mn出现异常的主要原因.以通济桥水库为鉴,建议深水型环保疏浚重点考虑底泥扰动及后续季节性水温分层对水质控制效果产生的影响.     

The occurrence of the cold-water coral Lophelia pertusa (Scleractinia) on oil and gas platforms in the North Sea: colony growth, recruitment and environmental controls on distribution

This study reports a newly established sub-population of Lophelia pertusa, the dominant reef-framework forming coral species in the north-east Atlantic, on oil and gas platforms in the northern North Sea. L. pertusa was positively identified on 13 of 14 platforms examined using existing oil and gas industry visual inspections. Two platforms were inspected in more detail to examine depth and colony size distributions. We recorded 947 colonies occurring between 59 and 132 m depth that coincides with cold Atlantic water at depths below the summer thermocline in the northern North Sea. We suggest that these colonies provide evidence for a planktonic larval stage of L. pertusa with recruits initially originating from populations in the north-east Atlantic and now self recruiting to the platforms. Size class distribution showed a continuous range of size classes, but with few outlying large colonies. The break between the largest colonies and the rest of the population is considered as the point when colonies began self recruiting to the platforms, resulting in greater colonization success. We present the first documented in situ colony growth rate estimate (26 +/- 5 mm yr(-1)) for L. pertusa based on 15 colonies from the Tern Alpha platform with evidence for yearly recruitment events starting the year the platform was installed. Evidence of contamination from drill muds and cuttings was observed on the Heather platform but appeared limited to regions close to drilling discharge points, where colonies experience partial as well as whole colony mortality.     

Climate induced temperature effects on growth performance, fecundity and recruitment in marine fish: developing a hypothesis for cause and effect relationships in Atlantic cod (Gadus morhua) and common eelpout (Zoarces viviparus)

Effects of global warming on animal distribution and performance become visible in many marine ecosystems. The present study was designed to develop a concept for a cause and effect understanding with respect to temperature changes and to explain ecological findings based on physiological processes. The concept is based on a wide comparison of invertebrate and fish species with a special focus on recent data obtained in two model species of fish. These fish species are both characterized by northern and southern distribution limits in the North Atlantic: eelpout (Zoarces viviparus), as a typical non-migrating inhabitant of the coastal zone and the cod (Gadus morhua), as a typical inhabitant of the continental shelf with a high importance for fisheries.Mathematical modelling demonstrates a clear significant correlation between climate induced temperature fluctuations and the recruitment of cod stocks. Growth performance in cod is optimal at temperatures close to 10°C, regardless of the population investigated in a latitudinal cline. However, temperature specific growth rates decrease at higher latitudes. Also, fecundity is less in White Sea than in North and Baltic Sea cod or eelpout populations. These findings suggest that a cold-induced shift in energy budget occurs which is unfavorable for growth performance and fecundity. Thermal tolerance limits shift depending on latitude and are characterized by oxygen limitation at both low or high temperatures. Oxygen supply to tissues is optimized at low temperature by a shift in hemoglobin isoforms and oxygen binding properties to lower affinities and higher unloading potential. Protective stimulation of heat shock protein synthesis was not observed.According to a recent model of thermal tolerance the downward shift of tolerance limits during cold adaptation is associated with rising mitochondrial densities and, thus, aerobic capacity and performance in the cold, especially in eurythermal species. At the same time the costs of mitochondrial maintenance reflected by mitochondrial proton leakage should rise leaving a lower energy fraction for growth and reproduction. The preliminary conclusion can be drawn that warming will cause a northern shift of distribution limits for both species with a rise in growth performance and fecundity larger than expected from the Q₁₀ effect in the north and lower growth or even extinction of the species in the south. Such a shift may heavily affect fishing activities in the North Sea.