Sediment transport below a small alpine reservoir desilted by controlled flushing: field assessment and one-dimensional numerical simulation

Purpose

Sediment transport and riverbed sedimentation were investigated in an alpine stream below a small hydropower reservoir desilted by a controlled sediment flushing (CSF) operation. The term “controlled” refers to the operational tasks implemented to mitigate the downstream environmental impact of the operation. The experimental dataset acquired before, during, and after the CSF was also used to carry out and calibrate a one-dimensional sediment transport model of the monitored event.

Materials and methods

The investigated reservoir is located in the central Italian Alps, and its original storage was 160,000 m³, about 30% filled by a mixture of sand and silt/clay before the CSF. Downstream sediment concentration was controlled by releasing clear water from upstream reservoirs and regulating the work of earth-moving equipment in the emptied reservoir. A 3.6-km-long reach with average slope of 0.015 was monitored: concentration and grain size of suspended sediment were measured during the CSF and the riverbed alteration was evaluated by volumetric sampling and measurements of the deposits’ thickness. Sedimentation and River Hydraulics—One Dimensional (SRH-1D) was used to simulate sediment transport during the monitored CSF. Model parameters were calibrated by comparing the computed and the observed amount of sediment deposited along the study reach.

Results and discussion

Sediment flushing was carried out in October 2010 for 3 days. Ca. 16,000 m³ of sediment were evacuated, representing approximately 30% silt/clay and 70% sand. 2.4 Mm³ of clear water was released to reduce sediment concentration and increase transport capacity downstream. About 3000 m³ of sand was deposited in the study reach after the CSF, with maximum height up to 0.2 m. Although the riverbed before the CSF was simply set as mono-granular, after calibrating the parameters, good agreement was achieved between the depositional pattern computed by SRH-1D and the one observed, both in terms of deposit thickness and grain size of deposited sediment. The sensitivity analysis revealed a major role of the parameters controlling bed mixing processes in affecting the simulated deposition after the CSF.

Conclusions

Sediment below 0.1 mm in diameter was not detected in river deposits after the flushing: the effects on river biota associated with substrate clogging by very fine sediment were therefore minimized. After proper calibration, 1-D sediment transport modeling can effectively support the planning of CSF operations: to minimize the downstream environmental effects, concurrently achieving acceptable flushing efficiency, the analyzed scenarios as well as the model outputs need to be carefully evaluated from a multidisciplinary perspective.

     

Early Development of the Mandarinfish, Synchiropus splendidus (Callionymidae), with notes on its Fishery and Potential for Culture

The mandarinfish, Synchiropus splendidus, is a small, pelagic-spawning enthic dragonet of the western Pacific. Although popular in the marine aquarium trade, little is known of its fishery or biology. All aquarium-trade animals are currently taken from the wild and the impact of heavy collecting is unknown. The specialized and selective nature of the fishery for mandarinfish is described and its potential to disrupt the mating system identified. As a possible alternative to wild capture and as an aid to sustainable exploitation, egg production and early development relevant to mariculture are described, including egg output, embryo, larva and post-settlement development to 30 days, based on live material. Egg output was determined for 40 females and ranged from 12 to 205 eggs. Embryo and larva development were rapid, with settlement occurring within 14 days at 24–26 °C, and at 3.5 mm TL. The swimbladder is retained in adults. Our limited attempts at raising the mandarinfish to settlement were encouraging and suggest an excellent potential for mariculture with implications for both conservation and improved maintenance of fish in captivity. At present, given that this species is difficult to maintain in captivity, it is only suitable for experienced aquarists. Preliminary diet information is provided. This revised version was published online in August 2006 with corrections to the Cover Date.     

A new acylated quercetin glycoside and other secondary metabolites from Helleborus foetidus

A new acylated flavonol glycoside, quercetin 3-O-(2-trans-caffeoyl)-alpha-L-arabinopyranosyl-(1-->2)-beta-D-glucopyranoside (1), together with the known 25R,26-[(beta-D-glucopyranosyl)oxy]-22alpha-hydroxy-5beta-furostan-3-beta-yl O-alpha-l-rhamnopyranosyl-(1-->4)-beta-D-glucopyranoside (2), anemonin (3), beta-D-glucosyl-p-hydroxyphenylethyl alcohol (4), and 1-beta-O-caffeoyl-D-glucose (5) were isolated from Helleborus foetidus leaves and identified on the basis of detailed spectral analysis.     

A case study of <Emphasis Type="Italic">Eucalyptus globulus</Emphasis> fingerprinting for breeding

• Introduction  

Tree genetic improvement programs usually lack, in general, pedigree information. Since molecular markers can be used to estimate the level of genetic similarity between individuals, we genotyped a sample of a Portuguese Eucalyptus globulus breeding population—a reference population of 125 individuals—with 16 microsatellites (SSR).     

Development and Implementation of a Forest Nursery Accreditation Policy at a Local Level in Leyte, Philippines

Through a series of workshops with the stakeholders including nursery operators, tree farmers, staff of the Department of Environment and Natural Resources, local government units and the academe, a forestry seedling nursery accreditation policy was developed. The resulting policy was subsequently implemented by the municipal government of Palompon, Leyte. The accreditation policy encouraged nursery operators to follow smallholder-based best management practices for tree nurseries. Implementation of the nursery accreditation policy improved farmers’ knowledge and skills in the production of high quality seedlings, encouraged adoption of BMP for forest nurseries, provided additional source of income for the farmers, enabled members of the groups operating the communal nursery to forge closer relationship with each other, encouraged utilization of farmers’ free time in productive activities, developed farmers’ confidence in producing high quality planting materials, and gained for the farmers favourable attention from various organizations and groups. The Bennett’s hierarchy of project outcomes showed that the implementation of accreditation scheme achieved high levels of outcomes, indicating that it led to substantial improvements in the lives of the farmers.     

Increase in milt production by hormonal treatment in the pejerrey fish Odontesthes bonariensis (Valenciennes 1835)

In spite of interest in the cultivation of the pejerrey fish Odontesthes bonariensis (Cuvier & Valenciennes 1835), there are few studies on subjects required to advance this activity. One of the problems is the synchronization of female and male maturation to provide eggs and sperm for larval production. The low volume of expressible milt, either in wild or culture fish, is a major problem. The aim of this work was to study the effectiveness of the administration of different hormones on sperm production in pejerrey. Milt production was enhanced by the injection of human chorionic gonadotropin (hCG) (16.7‐fold increase, 625 IU kg^?1), carp pituitary extracts (13.5‐fold increase, 30 mg kg^?1), salmon pituitary extracts (12.8‐fold increase, 30 mg kg^?1), salmon‐type gonadotropin‐releasing hormone analogue (GnRH) (16.7‐fold increase, 10 μg kg^?1) and mammalian‐type GnRH analogue (10.8‐fold increase, 20 μg kg^?1). Sperm concentration, motility and the fertilization rate were not statistically different compared with control groups. It was also demonstrated that sperm could be obtained off‐season. Taken together, hCG is recommended to stimulate pejerrey spermiation because it is effective in low doses is inexpensive and is widely available.     

Silvopastoral systems improve carbon stocks at livestock ranches in Tabasco,Mexico

Silvopastoral systems have great potential for storing carbon because of carbon assimilation in tree woody biomass, carbon input through litterfall and below-ground carbon turnover. In this study, we quantified and compared the carbon stocks at livestock ranches in Tabasco, Mexico, containing either scattered trees in grazing pastures (STP) or grass monocultures. Sampling plots were randomly established at each ranch where the above- and below-ground carbon stocks, carbon input from litterfall, grass production and arboreal biomass growth were measured. We found that silvopastoral systems stored an average of 257.45 Mg ha⁻¹ of soil organic carbon (SOC) compared to 119.17 Mg SOC ha⁻¹ at grass monoculture ranches (to 30 cm depth); silvopastoral systems also stored 44.64 Mg C ha⁻¹ in wood biomass; and, grass monocultures had greater cumulative grass biomass production. Overall, it is concluded that livestock ranches in Tabasco, Mexico, with scattered trees in grazing pastures stored 58.8% more carbon than those grass monocultures, with carbon stocks of 327.01 Mg C ha⁻¹and 134.47 Mg C ha⁻¹, respectively. The results are useful for land management decision making for sustainable livestock systems framed in the Sustainable Development Goals (SDGs).     

Soil chemical and biochemical properties of a salt-marsh alluvial Spanish area after long-term reclamation

Marisma, one of the largest salt-marsh alluvial areas in SW Spain, has been reclaimed since 1970 by artificial drainage and amendment with phosphogypsum (PG) so as to reduce Na⁺ saturation. Within the reclaimed area, two 250- × 20-m plots were treated as follows: (1) amendment with 25 Mg/ha of PG every 2 to 3 years between 1979 and 2003 (plot PY); (2) like PY but PG treatment stopped after 1997 (plot DR). A contiguous virgin Marisma salt-marsh plot (MV), neither drained nor amended, was the control. In MV, soil microbial biomass C, most enzyme activities and total organic C content were much greater than in PY and DR soils, despite the salinity stress. The decrease in soil organic matter content in PY and DR soils was likely due to cotton-cropping practices, which favoured the organic C mineralisation and nutrients removal by crops. Microbial activity of MV soil, probably stimulated by the rhizodepositions of the natural vegetation, did not suffer from the osmotic effect due to the raising of soil solution ionic strength. Microbial quotient could be ranked as MV > PY > DR, whereas the metabolic quotient had an opposite trend. Thus, both quotients suggested that the interruption of PG amendment was not favouring microbial activity. Principal component analysis clearly identified the chemical and biochemical soil properties mostly affected by the reclamation and also indicated the longer PG amendment in PY plot. Stepwise discriminant analysis identified two physiologically different types of soil microflora, one less active present in the MV virgin soil and another more active present in the reclaimed PY and DR soils.     

Influence of larval transport and temperature on recruitment dynamics of North Sea cod (Gadus morhua) across spatial scales of observation

The survival of fish eggs and larvae, and therefore recruitment success, can be critically affected by transport in ocean currents. Combining a model of early‐life stage dispersal with statistical stock–recruitment models, we investigated the role of larval transport for recruitment variability across spatial scales for the population complex of North Sea cod (Gadus morhua). By using a coupled physical–biological model, we estimated the egg and larval transport over a 44‐year period. The oceanographic component of the model, capable of capturing the interannual variability of temperature and ocean current patterns, was coupled to the biological component, an individual‐based model (IBM) that simulated the cod eggs and larvae development and mortality. This study proposes a novel method to account for larval transport and success in stock–recruitment models: weighting the spawning stock biomass by retention rate and, in the case of multiple populations, their connectivity. Our method provides an estimate of the stock biomass contributing to recruitment and the effect of larval transport on recruitment variability. Our results indicate an effect, albeit small, in some populations at the local level. Including transport anomaly as an environmental covariate in traditional stock–recruitment models in turn captures recruitment variability at larger scales. Our study aims to quantify the role of larval transport for recruitment across spatial scales, and disentangle the roles of temperature and larval transport on effective connectivity between populations, thus informing about the potential impacts of climate change on the cod population structure in the North Sea.     

Fish photobacteriosis—The importance of rapid and accurate identification of Photobacterium damselae subsp. piscicida

MALDI‐TOF MS was tested for the identification of Photobacterium damselae subsp. piscicida on isolates grown on two media, cultured at three incubation times and applied on the target plate by the direct sample spotting (DS), by the on‐target extraction (OTE) and by the full extraction (FE) method, in triplicates. The identification of samples grown on blood agar (BA) outperformed identification on tryptic soya agar (TSA) by 0.64% for DS and OTE. The OTE gave the highest scores in both culture media, all incubation times and replicates. Reliable 24‐hr species identification was 61.54%, 84.61% and 53.85% for samples grown on TSA and identified by DS, OTE and FE, respectively. For isolates grown on BA, they were 76.92%, 96.15% and 30.77%, respectively. When identified by OTE, the 48‐hr identification was 93.58%, but for 72 hr declined to 71.79%. The reliable identification with the highest score from the first measurement was 100% only for OTE from BA (24 hr), whereas OTE from TSA gave 84.61% (24 hr), 76.92% (48 hr) and 84.61% (72 hr). The reliable MALDI‐TOF MS identification of Ph. damselae subsp. piscicida is incubation time, media, target plate preparation and replicate‐dependent.