bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of tetragonality (c/a) on dielectric nonlinearity and direct current (dc) bias characteristics of (1-x)BaTiO3-xBi0.5Na0.5TiO3 ceramics
Authors: Yoon Seok-Hyun , Kim Mi-Yang , Kim Donghun
Published: October 2017

The incorporation of Bi0.5Na0.5TiO3 (BNT) into BaTiO3 (BT) in a (1-x)BT-xBNT system, with 0 ≤ x ≤ 0.3, creates an increase in the Curie temperature and the tetragonality (c/a) of the system. This causes (1) a decrease in the dielectric constants in the entire alternating current driving field range up to ∼4.5 V/μm; (2) an increase in the threshold field beyond which the dielectric constants begin to increase; and (3) a steep decrease in the dielectric constants when a direct current (dc) bias field is applied. The Preisach analysis shows that the enhancement of c/a, and its supposed increase in the lattice incompatibility during the domain wall motion, reduces the reversible domain wall contribution to polarization. This enhancement also reduces the mobility of the irreversible domain walls, thus requiring a higher driving field to trigger motion. The steep decrease in the dielectric constants under a dc bias field caused by the enhanced c/a can be associated with an increase in the anisotropy of the dielectric constants, which results in their reduction in the crystallographic c-axis direction. These results demonstrate that a high c/a is not desirable for capacitor applications, although it is the origin of ferroelectricity in perovskite materials.
Flexoelectric behavior in PIN-PMN-PT single crystals over a wide temperature range
Authors: Shu Longlong , Li Tao , Wang Zhiguo , Li Fei , Fei Linfeng , Rao Zhenggang , Ye Mao , Ke Shanming , Huang Wenbin , Wang Yu , Yao Xi
Published: October 2017

Flexoelectricity couples strain gradient to polarization and usually exhibits a large coefficient in the paraelectric phase of the ferroelectric perovskites. In this study, we employed the relaxor 0.3Pb(In1/2Nb1/2)O3-0.35Pb(Mg1/3Nb2/3)O3-0.35PbTiO3 (PIN-PMN-PT) single crystals to study the relationship between flexoelectric coefficients and the crystal structure. The flexoelectric coefficients in PIN-PMN-PT single crystal are found to vary from 57 μC/m at orthorhombic/monoclinic phase to 135 μC/m at tetragonal phase, and decreases to less than 27 μC/m in the temperature above Tm. This result discloses that ferroelectricity can significantly enhance the flexoelectricity in this kind of perovskite.
Charge-transfer mobility and electrical conductivity of PANI as conjugated organic semiconductors
Authors: Zhang Yahong , Duan Yuping , Song Lulu , Zheng Daoyuan , Zhang Mingxing , Zhao Guangjiu
Published: October 2017

The intramolecular charge transfer properties of a phenyl-end-capped aniline tetramer (ANIH) and a chloro-substituted derivative (ANICl) as organic semiconductors were theoretically studied through the first-principles calculation based on the Marcus–Hush theory. The reorganization energies, intermolecular electronic couplings, angular resolution anisotropic mobilities, and density of states of the two crystals were evaluated. The calculated results demonstrate that both ANIH and ANICl crystals show the higher electron transfer mobilities than the hole-transfer mobilities, which means that the two crystals should prefer to function as n-type organic semiconductors. Furthermore, the angle dependence mobilities of the two crystals show remarkable anisotropic character. The maximum mobility μmax of ANIH and ANICl crystals is 1.3893 and 0.0272 cm2 V−1 s−1, which appear at the orientation angles near 176°/356° and 119°/299° of a conducting channel on the a-b reference plane. It is synthetically evaluated that the ANIH crystal possesses relatively lower reorganization energy, higher electronic coupling, and electron transfer mobility, which means that the ANIH crystal may be the more ideal candidate as a high performance n-type organic semiconductor material. The systematic theoretical studies on organic crystals should be conducive to evaluating the charge-transport properties and designing higher performance organic semiconductor materials.
Controlling polymer capture and translocation by electrostatic polymer-pore interactions
Authors: Buyukdagli Sahin , Ala-Nissila T.
Published: October 2017

Polymer translocation experiments typically involve anionic polyelectrolytes such as DNA molecules driven through negatively charged nanopores. Quantitative modeling of polymer capture to the nanopore followed by translocation therefore necessitates the consideration of the electrostatic barrier resulting from like-charge polymer-pore interactions. To this end, in this work we couple mean-field level electrohydrodynamic equations with the Smoluchowski formalism to characterize the interplay between the electrostatic barrier, the electrophoretic drift, and the electro-osmotic liquid flow. In particular, we find that due to distinct ion density regimes where the salt screening of the drift and barrier effects occurs, there exists a characteristic salt concentration maximizing the probability of barrier-limited polymer capture into the pore. We also show that in the barrier-dominated regime, the polymer translocation time τ increases exponentially with the membrane charge and decays exponentially fast with the pore radius and the salt concentration. These results suggest that the alteration of these parameters in the barrier-driven regime can be an efficient way to control the duration of the translocation process and facilitate more accurate measurements of the ionic current signal in the pore.
Short electron bunches generated by perpendicularly crossing laser pulses
Authors: Horný Vojtěch , Petržílka Václav , Klimo Ondřej , Krůs Miroslav
Published: October 2017

Optical injection of electrons into a laser wakefield accelerator by a low intensity orthogonally colliding laser pulse is investigated using 2D particle-in-cell simulations. The collision of the main laser pulse driving the plasma wave in the cavitated regime and the low intensity injection pulse affects the trajectories of electrons in the crossing region. As a consequence, some electrons are ejected into the front part of the bubble, and these electrons are subsequently trapped in the rear part of the bubble. The injected and accelerated electron bunch reaches a peak energy of 630 MeV after 8 ps of acceleration being as short as 7.0 fs and is quasimonoenergetic with a low energy spread of 20 MeV (3.8%), having a charge of several dozens of pC and a relatively large emittance of 2.27 π · mm · mrad. Two main injection mechanisms—crossing beatwave injection and injection by laser field preacceleration—were identified.
Effects of individual and combined heat and drought stress during seed filling on the oxidative metabolism and yield of chickpea (Cicer arietinum) genotypes differing in heat and drought tolerance
Authors: Awasthi Rashmi , Gaur Pooran , Turner Neil C. , Vadez Vincent , Siddique Kadambot H. M. , Nayyar Harsh
Published: October 2017

Drought and heat stress are two major constraints that limit chickpea (Cicer arietinum L.) yield, particularly during seed filling. The present study aimed (i) to assess the individual and combined effects of drought and heat stress on oxidative metabolism during seed filling, and (ii) to determine any genetic variation in oxidative metabolism among genotypes differing in drought and heat tolerance and sensitivity. The plants were raised in outdoor conditions with two different times of sowing, one in November (normal-sown, temperatures <32°C−20°C (day–night) during seed filling), and the other in February (late-sown, temperatures >32°C−20°C (day–night) during seed filling). Plants were regularly irrigated to prevent any water shortage until the water treatments were applied. At both sowing times, the drought treatment was applied during seed filling (at ~75% podding) by withholding water from half of the pots until the relative leaf water content (RLWC) of leaves on the top three branches reached 42–45%, whereas leaves in the fully irrigated control plants were maintained at RLWC 85–90%. Drought-stressed plants were then rewatered and maintained under fully irrigated conditions until maturity. Several biochemical parameters were measured on the leaves and seeds at the end of the stress treatments, and seed yield and aboveground biomass were measured at maturity. Individual and combined stresses damaged membranes, and decreased PSII function and leaf chlorophyll content, more so under the combined stress treatment. The levels of oxidative molecules (malondialdehyde (MDA) and H2O2) markedly increased compared with the control plants in all stress treatments, especially across genotypes in the combined heat + drought stress treatment (increases in leaves: MDA 5.4–8.4-fold and H2O2 5.1–7.1-fold; in seeds: MDA 1.9–3.3-fold and H2O2 3.8–7.9-fold). The enzymatic and non-enzymatic antioxidants related to oxidative metabolism increased under individual stress treatments but decreased in the combined heat + drought stress treatment. Leaves had higher oxidative damage than seeds, and this likely inhibited their photosynthetic efficiency. Yields were reduced more by drought stress than by heat stress, with the lowest yields in the combined heat + drought stress treatment. Heat- and drought-tolerant genotypes suffered less damage and had higher yields than the heat- and drought-sensitive genotypes under the individual and combined stress treatments, suggesting partial cross-tolerance in these genotypes. A drought-tolerant genotype ICC8950 produced more seed yield under the combined heat + drought stress than other genotypes, and this was associated with low oxidative damage in leaves and seeds.
Seed production trait associations and inheritance in interspecific hybrids between Trifolium repens (white clover) and Trifolium uniflorum
Authors: Naeem Muhammad , Verry I. M. , Kemp P. D. , Millner J. P. , Williams W. M.
Published: October 2017

Trifolium repens L. (white clover) is an important component of temperate pastures, but its root morphology makes it vulnerable to drought and pest attack. T. uniflorum is a wild species, adapted to dry environments, with deep woody roots but poor vegetative growth and only 1–3 florets per inflorescence (head). Interspecific hybridisation to incorporate the drought tolerance and root characteristics of T. uniflorum into white clover led to primary hybrids (F1 and BC1) with poor seed production. Advanced-generation hybrids expressed high variation for almost all seed-production traits, and seed production responded to selection. To inform future breeding programs, trait associations and heritabilities were analysed. Numbers of heads per plant, florets per head and seeds per floret were important factors with moderate–high heritabilities. The derived traits, numbers of seeds per head, florets per plant and seeds per plant, expressed low–moderate heritabilities. No negative associations between seed production and root traits were found in the hybrids, nor were there any negative associations among head production, persistence and foliage production. Selection for improved seed-production traits should be effective without adversely affecting vegetative traits.
In silico evidence for sequence-dependent nucleosome sliding
Authors: Lequieu Joshua , Schwartz David C. , de Pablo Juan J.
Published: October 2017

Significance

The dynamic compaction of DNA into chromatin is essential for gene expression. Errors during compaction are associated with numerous diseases. Several molecular factors are known to affect chromatin dynamics, but their relative importance and the interplay between them are poorly understood. A detailed molecular model is used here to examine chromatin dynamics at the level of its most fundamental building block, namely the nucleosome. Nucleosome dynamics are demonstrated to be encoded in the DNA sequence itself, and key fundamental factors are uncovered that can significantly alter these dynamics at the molecular level. The results serve to complete a hitherto unavailable description of nucleosome dynamics by introducing previously unappreciated molecular processes, with the potential to influence macroscopic chromatin structure and genetics.
Barriers and Facilitators to Dispensing of Intranasal Naloxone by Pharmacists
Authors: Bakhireva Ludmila N. , Bautista Adriana , Cano Sandra , Shrestha Shikhar , Bachyrycz Amy M. , Cruz Theresa H.
Published: October 2017

Background: Although misuse of prescription opioids has reached epidemic proportions, pharmacy-based preventive services to combat this epidemic are limited. The aims of this study were to identify barriers and facilitators to the dispensing of intranasal naloxone (INN) by pharmacists in New Mexico. Methods: For this mixed-methods study, a qualitative component (focus group) informed the development of a quantitative component (electronic survey) distributed to all pharmacists registered with the New Mexico Board of Pharmacy and practicing in the state. A 46-item survey included questions about pharmacists’ concerns regarding dispensing INN, barriers and facilitators to dispensing INN, efforts needed to increase availability and utilization of pharmacist-dispensed INN, and characteristics of respondents and their pharmacies. Results: Pharmacists from all geographical regions and all types of pharmacy settings were represented in the sample (final N = 390, participation rate 23.5%, including a subset of 182 community pharmacists). The main barriers identified were (1) out-of-pocket costs for patients; (2) time constraints for pharmacists; and (3) inadequate reimbursement for pharmacists. The main facilitators were (1) increased awareness among opioid-using patients and family members about the need for INN; (2) additional education to the general public; and (3) additional training for pharmacists on how to initiate discussions about INN with high-risk patients. Some community pharmacists were concerned that INN dispensing would promote opioid abuse (16.5%) and attract undesirable clientele (14.3%). In a multivariable logistic regression analysis of a community pharmacy subset, a higher number of concerns about INN (odds ratio [OR] = 0.87; 95% confidence interval [CI]: 0.82–0.93) and a pharmacy setting in a chain grocery or a “big box” store (OR = 0.38; 95% CI: 0.16–0.92) were associated with decreased odds of dispensing INN. Conclusions: Effective intervention strategies for increasing dispensing of intranasal naloxone by pharmacists should focus on pharmacists’ concerns, include education to multiple audiences, and address provider-level, system-level, and society-level barriers.
Marine environmental impacts of power-desalination plants in Kuwait
Authors: Al-Dousari Ahmad , Al-Ghadban Abdul Nabi , Sturchio Neil C.
Published: October 2017

Kuwait's Ministry of Electricity and Water is planning to supplement the existing electric power generation capacity in the country by constructing new Combined-Cycle Gas-Turbine Stations at Shuaiba North Power Station and Subiya Power Station in order to meet the increasing power demand. The plans also include installation of a Multistage Flash Distillation Plant for seawater desalination at Shuaiba to increase Kuwait's supply of potable water.

Construction of these new facilities will impact the environment, and so therefore needed to be carefully assessed before the planned work could go ahead. Thus, the Kuwait Institute for Scientific Research conducted an environmental impact assessment for these sites, as per the guidelines of Kuwait's Environment Public Authority. The environmental impact assessment was performed in three parts: air, marine, and hydraulics, by separate multidisciplinary teams that conducted field surveys, took measurements, collected and analyzed samples, and in some cases, carried out predictive numerical modeling studies of the potential impact of plant operations on the surrounding environment. These studies took into account the impact of the already existing, as well as the planned, power generation and desalination facilities. This paper summarizes the final results of the marine environmental impact assessment, including the results of the hydraulic surveys and modeling studies.
Seagrass habitats in the Arabian Gulf: distribution, tolerance thresholds and threats
Authors: Erftemeijer Paul L. A. , Shuail Dawood A.
Published: October 2017

Seagrass habitats in the Arabian Gulf constitute a critical marine resource in the region, sustaining a high primary production, harbouring a high biodiversity of associated plant and animal species, and serving as important nursery grounds for penaeid shrimps, pearl oysters and various other marine organisms. The extreme environmental conditions in the Arabian Gulf, with major seasonal variations in water temperature and salinity, are tolerated by only three opportunistic seagrass species (Halodule uninervis, Halophila stipulacea and H. ovalis). Approximately 7,000 km2 of seagrass habitat has been mapped in the Arabian Gulf to date, with particularly extensive meadows in the coastal waters of the United Arab Emirates, Bahrain and Qatar. This area also sustains the world's second largest population of approximately 5800 dugongs, which feed almost exclusively on seagrasses. Meanwhile, massive land-reclamation projects and rapid industrial developments (including power- and desalination plants) are posing an unprecedented threat to seagrass habitats in this region. This paper provides a detailed overview of the known distribution of seagrass habitats in the Arabian Gulf and their tolerance thresholds for temperature, salinity, turbidity and sedimentation. The paper concludes with a summary of the main threats to seagrasses in the Gulf and recommendations for their conservation and management.
Baseline radionuclide specific activity in commercial fishes of Kuwait
Authors: Al-Ghadban A. N. , Uddin S. , Aba A. , Behbehani M. H.
Published: October 2017

Radionuclide concentration in commercial fish species of Kuwait has been determined primarily with the intention of creating the baseline for 210Po, 137Cs, 40K, 226Ra, 224Ra, 228Ra, and 90Sr. This baseline information can be useful for issuing food advisories and determining annual intakes and radiation doses due to fish consumption. The highest fresh weight concentration of 210Po and 90Sr was in Battan and the lowest in Sobaity. Highest fresh weight 40K concentration was observed in Meid and the lowest in Battan. The 224Ra, 226Ra and 228Ra concentrations were highest in Meid, whereas the lowest was in Nuwaibi. In all the collected fish samples, 137Cs was below the detection limit.
Spatiotemporal variability of satellite-derived colored dissolved and detrital organic materials in the South China Sea from 1997–2007
Authors: Xian Tao , Yang Yuan-Jian , Sun Liang , Fu Yun-Fei
Published: October 2017

The dominant spatial patterns and temporal variations of colored dissolved and detrital materials in the South China Sea were presented by Sea-viewing Wide Field-of-view Sensor derived data from September 1997 to December 2007. Seasonal and interannual variations of colored materials in the South China Sea were discussed for the first time. Results showed that high values of these materials were mainly within the regions with large mixing and large-scale upwelling induced by a seasonally reversing monsoon (e.g. Gulf of Tonkin and northwest of Luzon Island in winter, southeast of Vietnam in summer, etc.) and in coastal regions, particularly in the estuaries of the rivers in summer (e.g. Pearl River and Mekong River). By contrast, low values were observed in the regions of downwelling (northwest of Luzon Island in summer) and deep basin regions in the South China Sea all throughout the year. This variability is highly correlated with that of chlorophyll a, except for at some costal regions, e.g. the Pearl River estuary, where the colored materials seldom co-vary with chlorophyll-a over an established threshold. High concentration of colored material will reduce photo-biological processes at these regions in some months. The main South China Sea is still below the critical value, when comparing with the thresholds of the seasonal colored material concentrations in the Sea. Such conclusions may be useful for the management of the South China Sea environments.
Genetic diversity of potentially free-living Symbiodinium in the Xisha Islands, South China Sea: Implications for the resilience of coral reefs
Authors: Zhou Guowei , Huang Hui , Yu Ziniu , Dong Zhijun , Li Yuanchao
Published: October 2017

Free-living Symbiodinium have been the focus of considerable attention among coral reef researchers because they represent a source of symbionts for both recently recruited corals and adult corals that are subject to environmental stress (e.g. climate change). We evaluated the genetic diversity of free-living Symbiodinium in seawater collected from the Xisha Islands in the South China Sea using sequence analysis of the hypervariable region of the chloroplast 23S. We sequenced a total of 267 cloned gene fragments representing Symbiodinium in clades A, B, C, D, F, and G, of which 34 were distinct types. The diversity of free-living Symbiodinium types was high at all sites. The majority of Symbiodinium sequences belonged to clade C. There was no significant difference in Symbiodinium sequence types among sites or depths. Our results highlight the high diversity of free-living Symbiodinium pools in the coral reef environment and provide a foundation for future studies of the spatiotemporal distribution of Symbiodinium. Such information is critical to understand and predict the influence of symbiotic dinoflagellates on the adaptation of their host to environmental changes.
Seasonal variability of surface phytoplankton in the Northern South China Sea: A one-dimensional coupled physical-biogeochemical modeling study
Authors: Geng Bingxu , Li Shiyu , Wang Dongxiao , Hu Jiatang , Luo Lin , Wang Siying
Published: October 2017

The South China Sea is an oligotrophic marginal sea located in the tropical-subtropical Northwestern Pacific Ocean. Under the influences of monsoon winds, both the physical and biogeochemical processes exhibit distinct seasonal variability in the upper waters. In order to study the seasonal variations of surface phytoplankton, a one-dimensional coupled physical-biogeochemical model was developed and applied to the deep basins of the Northern South China Sea, away from the coastal upwelling regions. Forced under real-time surface monsoon winds and heat flux, the model reproduced the mixed layer depth, sea surface temperature and surface chlorophyll-a compared with satellite observations and previous reported values. In seasonal mean, the mixed layer depth was highest in winter (∼61.62 m) and lowest in spring (∼12.07 m). The sea surface temperature was lowest (∼25.05°C) in winter and highest (∼29.20°C) in summer. Furthermore, conspicuous phytoplankton blooms occurred in winter with the highest chlorophyll-a concentration up to ∼0.21 mg m−3. In other seasons, the concentration remained relatively low, especially in summer (∼0.05 mg m−3). The spatial distributions of phytoplankton were closely related with patterns of surface nutrient availability, as well as mixed layer depth and sea surface temperature. These relationships indicate that surface phytoplankton primary production was mainly controlled by nutrient availability, which was dominated by vertical turbulent diffusion in the deep basin of the northern Sea which is away from the coastal upwelling regions. Overall, our model results indicated that the seasonal variability of surface phytoplankton was modulated by coupled effects of physical and biogeochemical processes in the Northern South China Sea.
Sediment quality assessment of Klang Estuary, Malaysia
Authors: Naji Abolfazl , Ismail Ahmad
Published: October 2017

This investigation was conducted to determine metals contamination from anthropogenic sources in sediments of Klang Estuary. Surface sediments from Klang Estuary were analyzed for metals (Cd, Zn, Ni, Cu, Pb and Fe), organic carbon and particles sizes. Quality assessment of sediments was evaluated using modified degree of contamination (mCd) and pollution load index (PLI). A comparison was also made with sediment quality guideline values. The present study showed that highest concentrations of metals were found in stations with high anthropogenic discharge. The mCd and PLI suggested that degree of metals contamination in surface sediments could be classified as “low to moderate degree of contamination.” With the rapid economic development and urbanization around the Klang Estuary, ongoing monitoring studies on heavy metals contamination should focus on contaminant sources within the estuary.
Marine biodiversity and resource management – what is the link?
Authors: Staples Derek J. , Hermes Rudolf
Published: October 2017

Marine biodiversity refers to the variation of life at all levels and is much more than just a count of species. Marine biodiversity decline is occurring across the globe and is characterized not only by extinctions (sometimes local), but also by invasions and hybridizations, reductions in the abundance of some species, degradation of habitats and changes in ecosystem processes (e.g. cycling of water, nutrients and energy).

The major threats and causes of marine diversity can be categorized as (i) unsustainable resource use, (ii) land-based impacts, (iii) coastal and marine pollution, (iv) introduced invasive species and (v) climate change. All these pose major risks in tropical seas where the high biodiversity in the past has allowed the tropical ecosystems to provide more services with less variability than more temperate systems.

There is a strong link between better resource management and better biodiversity outcomes. With the introduction and acceptance of the concept of sustainable development, a way was opened up to ensure that human development did not impact irreversibly on the physical environment, thereby preserving biodiversity for future generation so that they could also enjoy the services that healthy ecosystems can provide. Along with the concept came a range of “approaches,” many of which developed in parallel by different sectors and disciplines. Because they were all developed to promote sustainable development there is considerable agreement on principles and management tools. This article proposes a course of action through an ecosystem approach for planning, implementation, and monitoring and evaluation that better integrates both ecosystem and sector management tools for more integrated management.

There have been so many failures and biodiversity continues to decline. Several reasons for these failures are grouped under four pillars that are considered essential for successful resource management. These are: (i) enabling policy/legislative environment, (ii) good governance and institutions, (iii) full participation and (iv) adequate resources-people and finances to implement the management system. The use of large marine ecosystem management, exemplified by the Bay of Bengal Large Marine Ecosystem Project, is put forward as an approach that can address some of the issues that jeopardize success.
Application of satellite multi-sensor techniques to detect upwellings and potential fishing grounds in Wakatobi Marine National Park, Southeast Sulawesi, Indonesia
Authors: Tadjuddah Muslim , Mustafa Ahmad , Pangerang Utama K. , Yasidi Farid
Published: October 2017

Information about Yellowfin Tuna fishing grounds is needed to develop the capture fisheries sector, which could be obtained through satellite multi-sensor mapping techniques. Fishermen often have difficulty determining where the fish are and when they can be caught in abundance. Knowing this information would sufficiently reduce operating costs. Mapping the fishing ground of Yellowfin Tuna would also avoid overfishing due to the concentration of fishing boats in one particular location, thus allowing the operation to be more effective and efficient.

The long-term aim of this research is to improve the welfare of fishermen in the Wakatobi district, Southeast Sulawesi, while the short-term goal is to map the fishing ground of Yellowfin Tuna (Thunnus albacares) with the application of multi-sensor satellite technology to detect upwellings. The benefits of this research are cost savings for the fishermen and providing a reference for the arrangement of management strategies of Yellowfin Tuna (Thunnus albacares) for sustainablity and continuity.

This study indicated that the average sea surface temperature in the west was 29.79°C, in the west-east an average of 29.70°C, in the east an average of 27.40°C and the east-west an average of 29.13°C. Chlorophyll-a in both the west and the west-east averaged 0.15 mg m−3, in the east 0.27 mg m−3 and in the east-west 0.21 mg m−3. High temperatues started in December and continued until February in the Wakatobi region, which moved from west to east.

Low temperature moved from east to west from June until August. Fronts occured arround Kaledupa and Koromaha reef in December, January and February, as well as in March, April and May around Kaledupa reef and Runduma Island. In June, July, August, September, October and November fronts were observed around Kapota reef, Kaledupa reef, Koromaha reef and Koka reef. Upwelling occured in Kapota reef, Kaledupa reef and Koka reef in June, and in July and August around Runduma Island, Kapota reef, and Kaledupa reef. Furthermore, upwelling in Kapota reef, Wangi-wangi Island, and Kaledupa reef was observed in September.
Habitat use by fishes of Lake Superior. I. Diel patterns of habitat use in nearshore and offshore waters of the Apostle Islands region
Authors: Gorman Owen T. , Yule Daniel L. , Stockwell Jason D.
Published: October 2017

Diel patterns of distribution of fishes in nearshore (15–80 m depth) and offshore (>80 m) waters of the Apostle Islands region of Lake Superior were described using bottom trawls, mid-water trawls, and acoustic gear during day and night sampling. These data revealed three types of diel migration: diel vertical migration (DVM), diel bank migration (DBM), and no migration. DVM was expressed by fishes migrating from benthopelagic to pelagic strata and DBM was expressed by fishes migrating horizontally from deeper waters in the day to shallower waters at night while remaining within the benthopelagic stratum. Most fishes that did not exhibit diel migration showed increased nighttime densities as a result of increased activity and movement from benthic to benthopelagic strata. Rainbow Smelt (Osmerus mordax), Cisco (Coregonus artedi), Bloater (C. hoyi), Kiyi (C. kiyi), juvenile Trout-Perch (Percopsis omiscomaycus), and adult siscowet (Salvelinus namaycush siscowet) exhibited DVM. Lake Whitefish (C. clupeaformis), lean Lake Trout (Salvelinus namaycush namaycush), and juvenile siscowet exhibited DBM. Adult Trout-Perch and adult Pygmy Whitefish (Prosopium coulteri) exhibited a mixture of DBM and DVM. Burbot (Lota lota), Slimy Sculpin (Cottus cognatus), Spoonhead Sculpin (C. ricei), and Deepwater Sculpin (Myoxocephalus thompsonii) did not exhibit diel migration, but showed evidence of increased nocturnal activity. Ninespine Stickleback (Pungitius pungitius) exhibited a mixture of DVM and non-migration. Juvenile Pygmy Whitefish did not show a diel change in density or depth distribution. Species showing ontogenetic shifts in depth distribution with larger, adult life stages occupying deeper waters included, Rainbow Smelt, lean and siscowet Lake Trout, Lake Whitefish, Pygmy Whitefish, Ninespine Stickleback and Trout-Perch. Of these species, siscowet also showed an ontogenetic shift from primarily DBM as juveniles to primarily DVM as adults. Across all depths, fishes expressing DVM accounted for 73% of the total estimated community areal biomass (kg ha−1) while those expressing DBM accounted for 25% and non-migratory species represented 2% of the biomass. The proportion of total community biomass exhibiting DVM increased with depth, from 59% to 95% across ≤30 m to >90 m depth zones. Along the same depth gradient, the proportion of total community biomass exhibiting DBM declined from 40% to 1%, while non-migrators increased from 1% to 4%. These results indicate that DVM and DBM behaviors are pervasive in the Lake Superior fish community and potentially provide strong linkages that effect coupling of benthic and pelagic and nearshore and offshore habitats.
Effects of water levels and water level regulation on the supply of suitable spawning habitat for eight fish guilds in the Bay of Quinte, Lake Ontario
Authors: Gertzen E. L. , Doka S. E. , Minns C. K. , Moore J. E. , Bakelaar C.
Published: October 2017

Lake Ontario water levels are regulated under the International Joint Commission's Order of Approval. We assessed the availability of spawning habitat for eight fish guilds (grouped by vegetation and spawning temperature preferences) that use nearshore habitat in the Bay of Quinte, Lake Ontario, under regulated and pre-project water level scenarios. Our model used habitat characteristics of depth, substrate, vegetation cover and temperature across 14,876 habitat units and guild-based habitat suitabilities to assess the weighted suitable area (WSA) available for spawning. During the modelled 1951–2000 period, regulated water levels were on average 0.25 m lower than pre-project levels and varied about half as much. Overall, the large and shallow upper bay within the Bay of Quinte benefited from pre-project flows whereas the smaller and deeper lower bay benefited from regulated flows. Higher variance in water levels increased highly suitable wetland area and higher mean water levels increased the availability of shallow flooded area in the upper and middle bays, where the bathymetry is gradually sloping. The number of days over which WSA was available was generally greater for high temperature guilds, and appeared to decrease when temperature mismatches occurred in a season. Results emphasize the complexity of the relationship between fish habitat supply and water level regime.
An integrated approach to identifying ecosystem recovery targets: Application to the Bay of Quinte
Authors: Blukacz-Richards E. A. , Koops M. A.
Published: October 2017

In 1985, the International Joint Commission identified the Bay of Quinte as an Area of Concern due to its degraded ecosystem. A Remediation Action Plan was established with delisting targets including the goals of decreasing phosphorous loading and restoring the upper (fish and wildlife) and lower (phytoplankton, zooplankton, and benthic invertebrates) trophic levels. We examined the consistency among seven Remedial Action Plan targets using Ecopath, a mass-balance model, for the upper Bay of Quinte for the post Zebra Mussel (Dreissena polymorpha) invasion period (1995–2002). We quantified the trophic consequences of bottom-up-control by gradually reducing the phytoplankton biomass until the Ecopath model became unbalanced (27% reduction). Replicate (n = 25) mass-balance solutions consistently showed that reductions in Zebra Mussel biomass were necessary to achieve mass-balance. This bottom-up control met the nutrient (total phosphorus), fish, benthic invertebrates, and phytoplankton population RAP targets. Based on these consistent results, it is recommended that future modelling efforts examine the effects of further phytoplankton biomass reductions.
Bioconcentration of benzo[a]pyrene in Chironomus riparius and Lumbriculus variegatus in relation to dissolved organic matter and biotransformation
Authors: Agbo Stanley O. , Akkanen Jarkko , Leppänen Matti T. , Kukkonen Jussi V. K.
Published: October 2017

The relative health of benthic invertebrate populations is threatened by both dissolved and strongly-bound contaminants. Sediment-bound contaminants can be mobilized and metabolized in the guts of deposit-feeders and may lead to even more potent derivatives. For this reason, measures of parent substance concentrations in organisms are not a suitable exposure indicator when substantial biotransformation can occur. In this study, we assessed the concentration of waterborne 14C-benzo[a]pyrene (BaP) in Chironomus riparius larvae and in the oligochaete Lumbriculus variegatus at different levels of dissolved organic carbon (DOC). These two species have different biotransformation capabilities. Polydimethylsiloxane (PDMS) fiber was used to assess the freely-dissolved concentrations for the prediction of uptake and elimination kinetics. Exposure concentrations decreased due to the presence of DOC. Radioactivity that corresponded to the metabolites exceeded 90% of total extractable fractions in C. riparius, and suggested that BaP metabolism was faster than uptake from solution. However, only 10% of the extracted activity was attributed to metabolites in L. variegatus. Measured tissue concentrations and model-predicted uptake and elimination rates showed that L. variegatus mainly accumulated parent compound, whereas C. riparius accumulated mainly metabolites. No effect of DOC was observed on the biotransformation of BaP in either species.
Endocrine disrupting chemicals in aquatic environments: A potential reason for organism extinction?
Authors: Wang Yan , Zhou Jin
Published: October 2017

The hazards of endocrine-disrupting chemicals (EDCs) in natural ecosystems are increasingly drawing public attention. These chemical agents affect aquatic life and its proliferation and can eventually cause reduced population density and species biodiversity. At present, EDCs are being considered as possible reasons for the functional degradation of aquatic ecosystems. Field and laboratory studies suggest that EDCs can disrupt the reproductive and developmental health of various species. Molecular evidence shows that EDCs exhibit genotoxicity and can destroy genetic diversity and structure. Evolutionary toxicology further demonstrates that EDCs can affect the pattern of natural selection and eventually lead to evolutionary potential (or adaptability) loss. Historical statistics and ecological risk estimation provided additional robust data to prove that EDCs contribute to population density and biomass decline. Therefore, EDCs may be a latent cause of aquatic species loss or extinction. In the present article, the extinction risk attributable to EDCs are briefly reviewed and discussed based on the aforementioned factors. The present study aims to assess the species vulnerability to extinction under EDCs exposure and provide a scientific basis for making policy decisions on wildlife resource conservation.
Benthic foodweb of a salt marsh in an artificial lagoon, central Japan
Authors: Kon Koetsu , Hoshino Yukihiro , Kanou Kouki , Okazaki Daisuke , Nakayama Satoko , Kohno Hiroshi
Published: October 2017

Salt marsh rehabilitations have been carried out globally, with the goal of recovering structural characteristics such as diversity or abundance. Functional properties (e.g. foodwebs) are also important but less is known about the effects of rehabilitation on such factors. We investigated the benthic foodweb in a reconstructed salt marsh, which consisted of marsh vegetation and mudflats, in the artificial Shinhama Lagoon, at the head of Tokyo Bay, central Japan. We used stable carbon and nitrogen isotope analysis to assess the contributions of primary producers (marsh plants, phytoplankton, microphytobenthos and macroalgae) as nutrient sources for benthic invertebrates in vegetated and unvegetated habitats. Phytoplankton contributed to approximately 27% of the diet of benthic invertebrates and was thus the highest contributor in both habitats. In addition, marsh plants contributed about 24% of the diet of the invertebrates in vegetated habitats, and microphytobenthos contributed around 22% of the diet in unvegetated habitats. These findings are consistent with those obtained from other intact salt marshes, suggesting that the artificial Shinhama Lagoon has evolved into a natural system in terms of the benthic foodweb approximately 30 years after reconstruction. Results indicate that functional properties can be recovered by marsh restoration, and that future rehabilitation programmes should aim to recover whole ecosystems, i.e. both structural characteristics and functional properties.
Trace metals and rare earth elements in Rock Oyster Saccostrea cucullata along the east coast of Peninsular Malaysia
Authors: Fuad M. M. , Shazili N. A. M. , Faridah M.
Published: October 2017

Trace metals and rare earth elements (REEs) in the soft tissue of rocky shore Rock Oyster, Saccostrea cucullata, along the east coast of Peninsular Malaysia were determined. Significant inter-spatial variations ( p < 0.05) in trace metals and REEs were recorded. Significant positive correlations ( p < 0.01) were found among REEs concentrations. A few significant correlations were found for trace metals and REEs. Average distribution of metals indicated that Johor State had the highest concentrations compared with Pahang and Terengganu for all metals, except for Pb and Cu. This could most likely be attributed to the highly urbanized and industrialized activities such as sewage discharge.

The metal accumulation patterns in the oyster indicated enrichment of essential metals. Sites with relatively high concentrations of the contaminant metals Hg, Cu, Pb and Zn were related to their close proximity to industrial and urban sites or to boating and aquaculture activities. Relative enrichment of Cu, Pb and Zn in oysters in the whole study even from relatively pristine areas is thought to be derived from natural sources as these metals are significantly correlated to REEs distribution. The distribution of REEs show close similarity between all sampling sites, suggesting that they are of similar origins. In all sites, typical saw-tooth chondrite-normalized patterns were observed, which strongly suggested the REEs bioaccumulated in oyster tissues is derived from geogenic sources. Typical deviations from this pattern were found for Ce and Eu and could be explained by their redox chemistry. Results of light to heavy REEs (LREE/HREE) ratios suggested REEs fractionation in coastline marine environment produced more light REEs and less heavy REEs absorbed in the soft tissue of S. cucullata. The ratio of La/Yb in the oyster of 27.3 was remarkably similar to Terengganu River basin soil of 33.0 and to Terengganu River sediment of 27.6. Comparison of metal concentration with maximum permissible limits of toxic metals in food established in different countries, as well as Malaysian Food Act 1983 and Food Regulations 1985 Fourteen Schedule, indicated values were well within safety levels, except for Cu and Zn. Along with its wide distribution on rocky shore areas along the east coast, the present results of trace metals and REEs recorded in soft tissue of S. cucullata collected from 14 sites along the east coast of Peninsular Malaysia served as baseline data for future reference.
Assessment of groundwater vulnerability to pollution of a wetland watershed: The case study of the Oualidia-Sidi Moussa wetland, Morocco
Authors: El Himer H. , Fakir Y. , Stigter T. Y. , Lepage M. , El Mandour A. , Ribeiro L.
Published: October 2017

The susceptibility of wetlands to continental pollution is closely related to the vulnerability of their surface and sub-surface watersheds. Therefore, to help manage wetlands, especially those fed by groundwater, it can be useful to assess the vulnerability of their aquifers. This approach is illustrated by the case study of the wetland of Oualidia-Sidi Moussa. Firstly, the hydrogeological basin of the wetland was identified. Vulnerability mapping was then performed using the specific Susceptibility Index (SI) method. Results indicated that the natural protection against pollution of the watershed of the Oualidia-Sidi Moussa wetland was low, and that the system was indeed affected by anthropogenic pollution. Preservation of its ecological value requires urgent management actions.
Modelling the photochemical generation kinetics of 2-methyl-4-chlorophenol, an intermediate of the herbicide MCPA (2-methyl-4-chlorophenoxyacetic acid) in surface waters
Authors: De Laurentiis Elisa , Minella Marco , Bodrato Marco , Maurino Valter , Minero Claudio , Vione Davide
Published: October 2017

2-Methyl-4-chlorophenol (MCP) is the main transformation intermediate of the herbicide MCPA in surface waters and it is more toxic than its parent compound. MCP is produced from MCPA by both direct photolysis and •OH reaction. The latter process has higher yield of MCP from MCPA: 0.5 vs. 0.3 for the direct photolysis. Our model results show that the formation rate of MCP would be higher in waters that contain low organic matter and high nitrate and nitrite. Such conditions are favourable to MCPA direct photolysis and •OH-induced transformation, which are both inhibited by organic matter, while •OH formation is enhanced by nitrate and nitrite. Good agreement is obtained between model predictions and field data of MCPA transformation in the Rhône river delta (Southern France). The field data also suggest that MCP undergoes slightly faster transformation than MCPA in that environment.
Planktonic community metabolism in two stratified Mediterranean reservoirs with different trophic status
Authors: Romero-Martínez Leonardo , Morales-Pineda María , Úbeda Bárbara , Loiselle Steven A. , Cózar Andrés , Gálvez José A.
Published: October 2017

Community metabolism plays a crucial role in the carbon dynamics of continental aquatic ecosystems. In the present work, two Mediterranean reservoirs (Southern Spain) with different trophic status were monitored during the stratified phase over two consecutive years (2009 and 2010) to evaluate community metabolic dynamics and potential controlling factors. Dark and light incubations were performed in order to estimate the daily rates of gross production (GP), community respiration (CR) and net community production (NCP). Temperature, irradiance, chlorophyll, phosphorus and carbon concentration were also measured at different depths within the mixed layer. On average, results showed heterotrophic behavior (GP < CR) in both reservoirs, which was particularly evident in the more eutrophic reservoir. Interannual climate variability was high due to the exceptionally rainy winter of 2010. This resulted in a significant decrease in the magnitude of the heterotrophic balance in both reservoirs. The change in NCP was especially evident in the most eutrophic reservoir where high water renewal rates lead to a lower CR. In general, NCP was found to be directly related to the ratio between the euphotic layer depth and the mixed layer depth, and inversely related to the particulate phosphorus concentration. Autotrophic behavior was only found in conditions of high irradiance (mixed layer shallower than euphotic layer), relatively low concentrations of dissolved organic carbon (<6 mg L−1) and particulate phosphorus (<10 μg L−1), and moderate chlorophyll concentration (2–9 μg L−1), albeit these conditions did not always lead to a net autotrophic balance.