Which group is best? Attributes of different biological assemblages used in freshwater biomonitoring programs

Of the many groups of organisms proposed for use in biomonitoring, assemblages of fish, algae, and benthic macroinvertebrates are the most commonly selected. Purported advantages and disadvantages of using these groups, along with those of zooplankton, were assembled from 65 different publications and websites. From these, 13 categories of advantages and nine of disadvantages were created. The diversity of the assemblage and its importance to the ecosystem were reported as advantages in >20% of citations for each group; these similarities suggest that some redundancy exists among the different groups in terms of these features. Likewise, sampling difficulties and lack of analytic metrics were disadvantages listed in >20% of citations for each group. Few reported advantages (e.g. recreational value of fish) or disadvantages (e.g. short generation time of algae) were unique for a particular assemblage. The validity of reported advantages and disadvantages were sometimes region specific, other times incorrect. The choice of which assemblage is most appropriate for a biomonitoring program ultimately depends on the characteristics of the area to be studied and the program objectives.     

Macroinvertebrate community response to acid mine drainage in rivers of the High Andes (Bolivia)

Several High Andes Rivers are characterized by inorganic water pollution known as acid mine drainage (AMD). The aim of this study was to assess the relationship between metal concentrations in the sediments and the macroinvertebrate communities in two river basins affected by AMD. In general, the taxon diversity of the macroinvertebrate community at the family level was low. The concentrations of Cd, Cu, Zn, Pb and Ni at mining sites were higher than at unpolluted sites. The pH of the water was alkaline (7.0-8.5) in unpolluted sites, whereas it dropped to very low values (<3) at mining sites. Redundancy Analysis (RDA) showed that pH was the best predictor of macroinvertebrate community richness. The number of macroinvertebrate families decreased gradually with increasing acidity, both in pools and riffles, though it is suggested that riffle communities were more affected because they are in closer contact with the acid water.     

Grazed Riparian Management and Stream Channel Response in Southeastern Minnesota (USA) Streams

The U.S. Department of Agriculture-Natural Resources Conservation Service has recommended domestic cattle grazing exclusion from riparian corridors for decades. This recommendation was based on a belief that domestic cattle grazing would typically destroy stream bank vegetation and in-channel habitat. Continuous grazing (CG) has caused adverse environmental damage, but along cohesive-sediment stream banks of disturbed catchments in southeastern Minnesota, short-duration grazing (SDG), a rotational grazing system, may offer a better riparian management practice than CG. Over 30 physical and biological metrics were gathered at 26 sites to evaluate differences between SDG, CG, and nongrazed sites (NG). Ordinations produced with nonmetric multidimensional scaling (NMS) indicated a gradient with a benthic macroinvertebrate index of biotic integrity (IBI) and riparian site management; low IBI scores associated with CG sites and higher IBI scores associated with NG sites. Nongrazed sites were associated with reduced soil compaction and higher bank stability, as measured by the Pfankuch stability index; whereas CG sites were associated with increased soil compaction and lower bank stability, SDG sites were intermediate. Bedrock geology influenced NMS results: sites with carbonate derived cobble were associated with more stable channels and higher IBI scores. Though current riparian grazing practices in southeastern Minnesota present pollution problems, short duration grazing could reduce sediment pollution if managed in an environmentally sustainable fashion that considers stream channel response.     

Sediment Quality Assessment in the Gulf of Gdańsk (Baltic Sea) Using Complementary Lines of Evidence

Sediments from Polish coastal environments were classified by a quality assessment approach that took into account trace metal and organic micropollutant concentrations, grain-size distribution, and organic carbon content. Generally, no benthic organisms were found at sites where sediments were classified as heavily polluted. However, areas characterized by a moderate contamination showed a variable composition of the benthic community and changing bioaccumulation patterns; therefore, no single species found in the Gulf of Gdańsk could be considered representative of the whole benthic environment. Although sediment monitoring must be considered a suitable tool to detect hot-spot pollution areas in coastal and inland waters, it should be complemented by bioaccumulation measurements to evaluate the actual risk posed by contaminants to benthic organisms. This “biological information” allows a better appreciation of the real benthic infaunal community exposure to chemicals and can usefully complement the existing sediment quality guidelines.     

Bioaccumulation and toxicity of a cationic surfactant (DODMAC) in sediment dwelling freshwater invertebrates

Dimethyldioctadecylammonium chloride (DODMAC, CAS No. 107-64-2) is the principal active component of Di(hydrogenated tallow alkyl) dimethylammonium chloride (DHTDMAC, CAS No. 61789-80-8), a cationic surfactant formerly used principally in laundry fabric softeners. After discharge to water, DODMAC partitions strongly to sediment, therefore the assessment of the effects of DODMAC to benthic organisms is essential in any risk assessment. Chronic toxicity studies were conducted with Lumbriculus variegatus (Oligochaete), Tubifex tubifex (Oligochaete) and Caenorhabditis elegans (Nematode). NOECs were greater than 5738, 1515 and 1351 mg/kg dw, respectively, even for sub-lethal effects. Measurement of the route of uptake of DODMAC by L. variegatus demonstrated the relative importance of uptake via ingestion (86%) compared with direct contact with the sediment and via pore water (14%). The overall tendency of DODMAC to bioaccumulate, however, was low with measured accumulation factors of 0.22 and 0.78 for L. variegatus and T. tubifex, respectively.     

永定河底栖动物生物完整性指数构建与健康评价

构建大型底栖动物生物完整性指数是河流健康评价与河流修复的重要步骤.根据2017年4月永定河流域23个采样点的大型底栖动物生物监测数据,基于监测点水质状况与栖息地质量综合评估指数得分,选择潮白河水系大型底栖动物类群相似且人为干扰较小的5个监测点作为参照区域,构建永定河B-IBI（大型底栖动物生物完整性指数）.通过对大型底栖动物33个生物参数的分布范围检验、判别能力分析和Spearman相关性检验,最终确定永定河B-IBI由总分类单元数、蜉蝣目（E）-襀翅目（P）-毛翅目（T）个体相对丰度、优势分类单元个体相对丰度、摇蚊科个体相对丰度、敏感类群分类单元数、科级耐污指数（family biotic index,FBI值）等6个核心参数构成.采用生物完整性研究中常用的比值法和三分法构建的B-IBI评价得分体系.结果表明,两种方法计算出的B-IBI均具有较高的判别能力,均能较好地判别参照水体和受损水体的健康状况,二者具有较高的相关性和一致性（R>0.90）.永定河河流健康评价结果表明,洋河、桑干河和永定河干流监测点B-IBI平均得分分别为1.97、1.86和1.78,妫水河B-IBI平均值为2.48,23个采样点中有16个处于较差状态,7个处于一般状态.相关性分析表明,B-IBI指数与栖息地质量综合评估指数得分、ρ（DO）呈显著正相关,与ρ（NH₄+）、浊度、电导率呈显著负相关,表明B-IBI指数对于栖息地人为干扰和水质污染均具有较强的指示作用.研究显示,永定河大型底栖动物生物完整性基本丧失,全流域底栖动物群落呈现全面退化趋势,识别影响大型底栖动物群落的关键要素、恢复永定河河流生态系统结构和功能研究亟待开展.      

Need for a global map of forest naturalness for a sustainable future

There is a growing need to assess and monitor forest cover and its conservation status over global scales to determine human impact on ecosystems and to develop sustainability plans. Recent approaches to measure regional and global forest status and dynamics are based on remotely sensed estimates of tree cover. We argue that tree cover should not be used to assess the area of forest ecosystems because tree cover is an undefined subset of forest cover. For example, tree cover can indicate a positive trend even in the presence of deforestation, as in the case of plantations. We believe a global map of forest naturalness that accounts for the bio-ecological integrity of forest ecosystems, for example, intact forests, old-growth forest patches, rewilding forests (exploited forest landscapes undergoing long-term natural succession), and managed forests is needed for global forest assessment.     

潮间带生物多样性与生境的相关性调查

本文从潮间带沉积物的粒径、分选系数及底栖生物群落结构阐明潮间带生态现状。潮间带生物群落的特征是环境及生物内部竞争相互作用的结果。以滨海规划工业区为例,调查了化工厂设计排污口所在滩涂的潮间带生态现状,其多样性与沉积物机械组成、海浪作用及生物群落内部竞争的平衡有关,并依此预测排污后的生态效应。     

A mathematical model to estimate nitrate release from ocher pellets applied to anaerobic benthic sediment

A mathematical model was developed to estimate nitrate release from ocher pellets in benthic sediment. Ocher pellets, called “limnomedicine,” consisting of ocher and calcium nitrate were used to suppress phosphorus release from contaminated sediment under anaerobic conditions. The proposed model represents the fate and transport of nitrate released from the pellets, in both the water column and the sediment. Most of the nitrate (83.6%) released from the pellets was consumed in the degradation of organic matter and FeS in the sediment over a period of 12 days. While an increase in pellet dosage helps to accelerate the sediment treatment rate, it also has the effect of increasing the mass of nitrate that diffuses into the water column. Quantitative analysis of these effects using the proposed mathematical model makes it possible to determine the proper pellet dosage based on sediment conditions such as organic matter content.