Changes to freshwater mussel assemblages after 25 years of impoundment and river habitat fragmentation

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Multi‐decadal climate and fishing predictors of abundance for U.S. South Atlantic coastal fishes and invertebrates

Abundance of marine stocks fluctuates in response to both internal processes (e.g., density dependence) and exogenous drivers, including the physical environment, fishing, and trophodynamic interactions. In the United States, research investigating ecosystem drivers has been focused in data‐rich systems, primarily in the North Atlantic and North Pacific. To develop a more holistic understanding of important ecosystem drivers in the Southeast U.S. continental shelf Large Marine Ecosystem, we applied generalized linear and dynamic linear modeling to investigate the effects of climate and fishing covariates on the relative abundance trends of 71 demersal fish and invertebrate species sampled by a coastal trawl survey during 1990–2013. For the assemblage as a whole, fishing effects predominated over climate effects. In particular, changes in trawling effort within the penaeid shrimp fishery governed abundance trends of bony fishes, invertebrates, and elasmobranchs, a likely result of temporal changes in bycatch mortality. Changes in trawling intensity induced changes in overall community composition and appear to have altered trophic interactions among particular species. Among climate indices investigated, the Pacific Decadal Oscillation and the Western Bermuda High Index were most prevalent in well‐supported dynamic linear models. Observed annual abundance trends were synchronous among some taxonomically related species, highlighting similar responses to exogenous influences based on life history. This study strengthens the foundation for generating hypotheses and advancing ecosystem‐based fisheries research within the region.     

The effect of feeding commercial diets on the development of juvenile crucian carp (Carassius carassius,L.). Part 1: Skeletal deformations

The crucian carp (Carassius carassius, L.) is a cyprinid freshwater species, whose wild‐living populations have decreased in recent years due to an increasing competition of invasive species. Several initiatives were launched, attempting to reintroduce this fish back into its native open waters, which requires the use of crucian carp fry grown under controlled conditions. However, the use of popular commercial diets results in severe developmental abnormalities. The aim of this study was to analyse the impact of feeding natural feed (Chironomidae sp. larvae) or two popular commercial diets on the skeletal development of crucian carp juveniles. Whole‐mount staining and histological methods were used in the study. Skeletal tissues of fish fed both commercial diets were demineralized and displayed a variety of deformities, such as abnormal vertebral spines and vertebral fusion, as well as a new type of deformation, which involved the action of dorsal fin pterygiophores upon the spine. Finally, a novel analytical method was proposed, which utilizes LA‐ICP‐MS for the estimation of bone mineralization. The study proved that basic commercial diets are inadequate for the rearing of crucian carp juveniles.     

Soil physical characteristics of peat soils

Drainage and intensive use of fens lead to alterations in the physical characteristics of peat soils. This was demonstrated using parameters of water balance (available water capacity) and the evaluated unsaturated hydraulic conductivity. Deriving the distribution of the pore size from the water retention curve was flawed because of shrinkage due to drainage, especially at high soil water potentials. These errors became greater as the peat was less influenced by soil‐genetic processes. The water retention curves (desorption) evaluated in the field and the laboratory satisfactorily corresponded. However, the wetting‐ and drainage‐curves obtained in the field differed up to 30 vol.‐% water content at same soil water potentials. These differences were largely due to a wetting inhibition.     

Model calculations of water dynamics in lysimeters filled with granular industrial wastes

A three‐year long lysimeter experiment with a fine‐grained aluminum (Al) recycling by‐product and a mixture of this by‐product and a coal combustion waste was conducted. The wastes were proposed as possible soil substitutes in an engineered surface barrier covering a potash mining residue mount. To evaluate the suitability of the wastes as surface barrier material, their hydrological behavior under field conditions must be known. Lysimeter experiments provide one means to study the hydrological behavior of soils or soil‐like materials. However, it is difficult to estimate the long‐term hydrological behavior from short‐term lysimeter studies. The present study was conducted therefore to derive from short‐term lysimeter observations the long‐term hydrological behavior of the two waste materials. The lysimeter data were used to calibrate the one‐dimensional soil water flow model HYDRUS‐1D. With the calibrated model, hydrological simulations for the site of the residue mount were carried out for a period of 31 yr. Calculated long‐term annual seepage from the lysimeters was 237 mm for the pure Al waste and 186 mm for the mixture, or 39% and 24% of the average annual precipitation (764 mm). The average discharge of the bare mount is 482 mm or 63%. We conclude that a soil cover could considerably reduce the discharge and that the mixture is better suited as surface barrier than the pure Al waste.     

Assessing the sublethal impacts of anthropogenic stressors on fish: An energy‐budget approach

Fish are increasingly exposed to anthropogenic stressors from human developments and activities such as agriculture, urbanization, pollution and fishing. Lethal impacts of these stressors have been studied but the potential sublethal impacts, such as behavioural changes or reduced growth and reproduction, have often been overlooked. Unlike mortality, sublethal impacts are broad and difficult to quantify experimentally. As a result, sublethal impacts are often ignored in regulatory frameworks and management decisions. Building on established fish bioenergetic models, we present a general method for using the population consequences of disturbance framework to investigate how stressors influence ecologically relevant life processes of fish. We partition impact into the initial energetic cost of attempts to escape from the stressor, followed by the energetic impacts of any injury or behavioural change, and their consequent effects on life processes. As a case study, we assess the sublethal effects of catch and release angling for the European sea bass (Dicentrachus labrax, Moronidae), a popular target species for recreational fishers. The energy budget model described is not intended to replace existing experimental approaches but does provide a simple way to account for sublethal impacts in assessment of the impact of recreational fisheries and aid development of robust management approaches. There is potential to apply our energy budget approach to investigate a broad range of stressors and cumulative impacts for many fish species while also using individual‐based models to estimate population‐level impacts.     

The Effect of AQUI‐S® Sedation on Primary,Secondary, and Tertiary Stress Responses during Salmon Smolt,Salmo salar L., Transport and Transfer to Sea

The purpose of this study was to determine the effect of AQUI‐S^® (5.0 mg/L) sedation compared with nonsedation on the primary (plasma cortisol), secondary (osmoregulation), and tertiary (mortality) stress responses in Atlantic salmon smolts during transport and transfer to sea. AQUI‐S sedation during on‐ and off‐loading sufficiently reduced the primary stress response to lower mortality (2.5%) during transfer to sea compared with unsedated fish, which experienced a mortality rate above 11.5%. The unsedated fish experienced an acute mortality, which only stabilized 16 d after the transport. None of the secondary stress responses measured in this experiment could contribute in explaining this phenomenon, with the possible exception of plasma magnesium. While osmolality and chloride increased in both groups during the experiment, it did not seem to be related to the difference in the primary stress response documented in the sedated and unsedated groups. It instead appeared to be an effect of the salinity change from freshwater to seawater after transport. Plasma magnesium differed between the groups, while plasma magnesium in the AQUI‐S‐sedated group returned to prestress levels 12 h after transport. The unsedated group showed no such recovery even 1 wk after transport, which may indicate a disturbance in hydromineral balance and give plausible explanation for delayed mortality this group experienced. AQUI‐S shows promise as a stress‐reducing sedative for Atlantic salmon smolts and if used properly could improve animal welfare and survivability during and after common aquaculture‐related incidents.     

Antifungal activity of resveratrol oligomers from Cyphostemma crotalarioides

Resveratrol and its oligomers: ε-viniferine, gnetin C, Pallidol and gnetin E, as well as three new dehydrodimers, cyphostemmines A–C, have been isolated from the roots of Cyphostemma crotalarioides (Ampelidaceae). Such compounds have not been reported previously in the family Ampelidaceae. Cis ε-viniferin has also been characterized as a minor component of the extract; it may have undergone partial transformation in solution into trans ε-viniferin. ©1999 Society of Chemical Industry     

Insecticidal activity of daphnane diterpenes from Lasiosiphon kraussianus (Meisn) (Thymelaeaceae) roots

A methanol extract of roots of Lasiosiphon kraussianus (Meisn) (Thymelaeaceae) showed potent insecticidal activity against Aphis gossypii (Glov) and Drosophila melanogaster (Meig). Bioassay-driven fractionation of this extract led to the isolation and characterisation of two known daphnane diterpenoids: Excoecaria toxin (1) and wikstrotoxin D (2) . The two natural products were inferior to methomyl in activity against A gossypii and Myzus persicae (Sulz) in contact assays but were superior in ingestion assays against D melanogaster. This is the first report on insecticidal activities of compounds 1 and 2 . AChE was insensitive to the two natural products. © 1999 Society of Chemical Industry     

Genetic relationship of diploid wheat (<Emphasis Type="Italic">Triticum</Emphasis> spp.) species assessed by SSR markers

Genetic diversity of 139 accessions of diploid Triticum species including Triticum urartu, Triticum boeoticum and Triticum monococcum was studied using 11 SSR (simple sequence repeats) markers. A total of 111 alleles with an average of 10 alleles per locus were detected. The polymorphism information content (PIC) of each SSR marker ranged from 0.30 to 0.90 with an average value of 0.62. Among the three Triticum species T. urartu had the highest number of total alleles (Na?=?81), private alleles (Npa?=?15) and showed higher genetic diversity (Hex?=?0.58; PIC?=?0.54). The genotypes from Turkey exhibited the highest genetic diversity (PIC?=?0.6), while the least diversity was observed among 4 Georgian accessions (PIC?=?0.11). Cluster analysis was able to distinguish 139 wheat accessions at the species level. The highest genetic similarity (GS) was noted between T. boeticum and T. monococcum (GS?=?0.84), and the lowest between T. urartu and T. monococcum (GS?=?0.46). The grouping pattern of the PCoA analysis corresponded with cluster analysis. No significant differences were found in clustering of T. urartu and T. monococcum accessions with respect to their geographic regions, while within T. boeoticum species, accessions from Iran were somewhat associated with their geographical origin and clustered as a close and separate group. The results from our study demonstrated that SSR markers were good enough for further genetic diversity analysis in einkorn wheat species.