Evaluating the performance of benthic multi-metric indices across broad-scale environmental gradients

The usefulness of benthic multi-metric indices when assessing seafloor integrity across broad environmental gradients should be deliberated, as their lack of transparency might hide important sources of variation and fail to identify environmental change. This study compares the performance of two multi-metric indices; the Benthic Quality Index (BQI) and the Brackish water Benthic Index (BBI) between three sub-basins in the Baltic Sea. Both indices reflect the salinity-driven gradient in macroinvertebrate diversity and composition as well as changes in bottom water oxygen concentrations. The relative contribution of predictor variables for explaining index variation does, however, differ between sub-basins, resulting in the indices representing different aspects of the benthic community along the environmental gradient. This context-dependency is caused by inherent differences in benthic community characteristics between the sub-basins of the Baltic Sea, and how the communities are portrayed by the indices. An increased transparency of the importance of the different predictors for directing index values is needed for coherent classifications over broad environmental gradients, such as those occurring in large estuarine water bodies. Use of a weight of evidence table to combine multiple indicators would preserve transparency and be more likely to provide a robust assessment method that would detect seafloor degradation at an early stage.     

Developing and testing alien species indicators for Europe

Alien species indicators provide vital information to the biodiversity policy sector on the status-quo and trends of biological invasions and on the efficacy of response measures. Applicable at different geographical scales and organizational levels, alien species indicators struggle with data availability and quality. Based on policy needs and previous work on the global scale, we here present a set of six alien species indicators for Europe, which capture complementary facets of biological invasions in Europe: (a) an combined index of invasion trends, (b) an indicator on pathways of invasions, (c) the Red List Index of Invasive Alien Species (IAS), (d) an indicator of IAS impacts on ecosystem services, (e) trends in incidence of livestock diseases and (f) an indicator on costs for alien species management and research. Each of these indicators has its particular strengths and shortcomings, but combined they allow for a nuanced understanding of the status and trends of biological invasions in Europe. We found that the scale and impact of biological invasions are steadily increasing across all impact indicators, although societal response in recent years has increased. The Red List Index is fit-for-purpose and demonstrates that overall extinction risks (here shown for amphibians in Europe) are increasing. Introduction pathway dynamics have changed, with some pathways decreasing in relevance (e.g., biological control agents) and others increasing (e.g., horticultural trade) providing a leverage for targeted policy and stakeholder response. The IAS indicators presented here for the first time on a continental basis serve as a starting point for future improvements, and as a basis for monitoring the efficacy of the recent EU legislation of IAS. This will need a better workflow for data collection and management. To achieve this, all main actors must work toward improving the interoperability among existing databases and between data holders.     

Measurement and Selection of Parasitoid Quality for Mass-Reared Trichogramma minutum Riley Used in Inundative Release

Parasitoid quality, subject to both genetic and environmental influences, is critical to the success of any biological control program, however, its measurement and improvement is poorly understood. In this study, a classic genetic approach is taken to develop two indices, namely a character index and a fitness index, for the measurement and selection of high quality parasitoids used in inundative release. Six life-history traits and corresponding fitness components in 33 inbred strains of Trichogramma minutum were used to generate both genotypic and phenotypic variance-covariance matrices that then allowed for the construction of the indices. Most traits and their fitness components were positively correlated, both phenotypically and genotypically, with lifetime fecundity and the number of female offspring appearing to have an important influence. Selection of the top three strains showed that parasitoid quality could be improved by 36% using the character index and possibly up to 150% using the fitness index. The two indices were linearly correlated suggesting that either could be used to measure quality. The character index is recommended because it requires information on only three life-history traits (fecundity, number of female offspring, and number of male offspring) and has highly correlated responses of fitness components. Our work demonstrates that the best quality T. minutum will be obtained by using the character index to select for inbred strains which have high fecundity and number of female offspring.     

Mosquitoes and West Nile virus along a river corridor from prairie to montane habitats in eastern Colorado

We conducted studies on mosquitoes and West Nile virus (WNV) along a riparian corridor following the South Platte River and Big Thompson River in northeastern Colorado and extending from an elevation of 1,215 m in the prairie landscape of the eastern Colorado plains to 1,840 m in low montane areas at the eastern edge of the Rocky Mountains in the central part of the state. Mosquito collection during June‐September 2007 in 20 sites along this riparian corridor yielded a total of 199,833 identifiable mosquitoes of 17 species. The most commonly collected mosquitoes were, in descending order: Aedes vexans, Culex tarsalis, Ae. dorsalis, Ae. trivittatus, Ae. melanimon, Cx. pipiens, and Culiseta inornata. Species richness was higher in the plains than in foothills‐montane areas, and abundances of several individual species, including the WNV vectors Cx. tarsalis and Cx. pipiens and the nuisance‐biter and potential secondary WNV vector Ae. vexans, decreased dramatically from the plains (1,215‐1,487 m) to foothills‐montane areas (1,524‐1,840 m). Ae. vexans and Cx. tarsalis had a striking pattern of uniformly high abundances between 1,200‐1,450 m followed by a gradual decrease in abundance above 1,450 m to reach very low numbers above 1,550 m. Culex species were commonly infected with WNV in the plains portion of the riparian corridor in 2007, with 14 of 16 sites yielding WNV‐infected Cx. tarsalis and infection rates for Cx. tarsalis females exceeding 2.0 per 1,000 individuals in ten of the sites. The Vector Index for abundance of WNV‐infected Cx. tarsalis females during June‐September exceeded 0.5 in six plains sites along the South Platte River but was uniformly low (0–0.1) in plains, foothills and montane sites above 1,500 m along the Big Thompson River. A population genetic analysis of Cx. tarsalis revealed that all collections from the ≈190 km riparian transect in northeastern Colorado were genetically uniform but that these collections were genetically distinct from collections from Delta County on the western slope of the Continental Divide. This suggests that major waterways in the Great Plains serve as important dispersal corridors for Cx. tarsalis but that the Continental Divide is a formidable barrier to this WNV vector.     

The impact of regional-scale changes in the weather on the long-term dynamics of Eudiaptomus and Daphnia in Esthwaite Water, Cumbria

1. Year‐to‐year changes in the weather have a profound effect on the seasonal dynamics of zooplankton in lakes. Here, I analyse some zooplankton data from Esthwaite Water in Cumbria and demonstrate that much of the recorded inter‐annual variation can be related to regional‐scale changes in the weather.
2. The first data set analysed shows the effect of changes in the water temperature on the winter abundance of the calanoid copepod Eudiaptomus gracilis. The highest numbers of Eudiaptomus were recorded when the winters were mild and the lowest when the winters were cold.
3. Winter temperatures in northern and western Europe are now known to be influenced by the atmospheric feature known as the North Atlantic Oscillation (NAO). Positive values of the NAO are associated with mild winters and westerly winds and there was a significant positive correlation between the winter abundance of Eudiaptomus in Esthwaite Water and this empirical index of change.
4. The second data set analysed shows the effect of wind‐induced mixing on the summer abundance of Daphnia. The highest numbers of Daphnia were recorded in years when the early summer thermocline was deep and the lowest number in years when the thermocline was shallow.
5. One of the most important factors influencing the depth of the early summer thermocline in the English lakes is the position of the north‐wall of the Gulf Stream. Southerly movements of the Gulf Stream are typically associated with higher winds, whilst northerly movements are associated with stable conditions. In Esthwaite Water, a significant positive correlation was recorded between the abundance of Daphnia and the depth of the early summer thermocline and significant negative correlations between the same variables and the position of the Gulf Stream.
6. A detailed analysis of the seasonal variations recorded in one calm and one windy year suggest that the main factor responsible for these correlations was the entrainment of nutrients which then stimulated the growth of edible algae. Daphnia numbers were low in 1968 (a ‘north’ Gulf Stream year which was relatively calm) and high in 1972 (a ‘south’ Gulf Stream year with intense wind‐mixing).     

Using the Ecological Risk Index Based on Combined Watershed and Administrative Boundaries to Assess Human Disturbances on River Ecosystems

Efforts at the restoration of river ecosystems are needed not only in local habitats but are also important in terrestrial regions. Large-scale assessment of human activities can be useful in integrated watershed management. In this study, we modified the Ecological Risk Index (ERI) by considering the spatial distribution of human activities in China's Haihe River Basin (HRB). The stressor factors of human activities included population, impervious surface, cattle, agricultural land use, industry, fertilizers, pesticides, water conservation facilities, and roads. A total of 423 assessment units in the HRB were created by combining watershed and administrative boundaries to analyze the spatial distribution of human activities. Two index options, the ERI (including all stressors) and the ERI-D (excluding reservoirs and sluices), were examined for different management objectives. All the stressors and both ecological risk indices (ERI and ERI-D) were ranked in four levels: low, moderate, high, and very high. Our study demonstrated that the ERI and ERI-D can provide an overview of the spatial pattern of human stressors related to river ecosystems across a large geographic region. The approach developed in this study is useful for prioritizing management actions in targeted areas.     

Growth performance,haematological assessment and chemical composition of Nile tilapia,Oreochromis niloticus (Linnaeus, 1758) fed different levels of Aloe vera extract as feed additives in a closed aquaculture system

A 105-day experimental trial was conducted to assess different levels of dietary Aleo vera extract supplementation on water quality parameters, proximate composition, growth performance and haematological parameters of fry Oreochromis niloticus. Four different percentages of dietary leaf extract powder of Aleo vera (ALE) with a basal feed, designated as, i.e., T0 (Control group; without ALE), T1 (1% ALE), T2 (2% ALE), and T3 (3% ALE). Fish fry was reared in concrete tanks (7.0 m, 1.6 m, 1.0: L, W, H; water volume 11.2 m3/tank), with an average initial weight 4.04 ± 0.03 g/ fry, and each treatment was triplicated. Fry was randomly distributed at a stocking rate of 450 individuals/ tanks. The water quality parameters revealed that temperature, pH, salinity, dissolved oxygen (DO) and nitrates were found in a promising range as given by FAO/WHO limits. However, the record values obtained for Electric Conductivity (EC), Total dissolved solids (TDS), and alkalinities were not found in all tanks' suitable range according to FAO/WHO limits. The results revealed a significant impact of different percentages of dietary ALE supplementation on fry's body composition and haematological parameters. Moreover, the final body weight, final body length, average daily weight gain (g), net weight gain (g) and specific growth rate (%) were significantly higher (p < 0.05) in T1 and T2 compared with T0 and T3 treatments. The poorest feed conversion ratio was recorded in the T2 group compared with other treatments. Thus, the current study provides information about the nutritional quality of Nile tilapia culturing in Pakistan.     

Angiotensinogen promoter and angiotensinogen II receptor type 1 gene polymorphisms and incidence of ischemic stroke and neurologic phenotype in Fabry disease

Abstract

Context: Stroke and/or white matter lesions (WMLs) are significant in Fabry disease. Polymorphisms of angiotensinogen (AGT), AGT Promoter and angiotensinogen II receptor type 1 (AGTR1) are correlated with WMLs.

Objectives: We compared AGT. AGT Promoter and AGTR1 genotypes to stroke incidence, Fabry-specific [Mainz Severity Score Index (MSSI)] severity score, and neurologic sub-score (n-MSSI).

Methods: Sixty-three Fabry patients and 49 matched controls plus historic controls were genotyped. Institutional Review Board approval was received.

Results. C and/or CC alleles of AGT Promoter and AGTR1 were significantly correlated with stroke and n-MSSI.

Discussion/conclusion: Findings are suggestive of role of AGT Promoter and AGTR1 genotypes in Fabry phenotypes.     

A variable selection index for the compensation of correlated genetic change

Summary A selection index for two traits has been constructed which allows partial restriction for one of the traits. The index is used in a situation where correlated response to selection in one sex is compenstated for by selection for other traits in the opposite sex. A numerical example is given.     

Understanding seagrass resilience in temperate systems: the importance of timing of the disturbance

Temperate seagrass meadows form valuable ecosystems in coastal environments and present a distinct seasonal growth. They are threatened by an increasing amount of stressors, potentially affecting their capacity to recover from disturbances. We hypothesized that their resilience to disturbances is affected by seasonal dynamics. Hence, we investigated the effect of the timing of the disturbance on seagrass Leaf Area Index (as a proxy for presence, or ‘visible’ status), recovery from disturbance (as a proxy for meadow resilience), and rhizome carbohydrates (as a proxy for longer term resilience) by a series of four disturbance-recovery field experiments spread over the growing season at two sites in Shandong Province, China. During the course of the growing season, we found the highest recovery at the start of the growing season, lowest recovery when Leaf Area Index peaked around mid-growing season, and intermediate recovery when Leaf Area Index decreased at the end of the growing season. Rhizome carbohydrates were not affected by disturbances during any of the four experimental periods and could not explain the low recovery during mid-growing season. The two sites differed in exposure and in the occurrence of incidents like a green tide and storms, which affected recovery. However, general patterns were similar; timing strongly influenced the indicator of meadow resilience and its correlation with presence during the two main seagrass growth phases. Our results emphasize the importance of carefully considering timing in the evaluation of seagrass resilience in temperate systems. Furthermore, our study implies that, to effectively protect seagrass beds, conservation management should aim at avoiding disturbances particularly during the peak of the growing season, when resilience is lowest.