Impact of Didymosphenia geminata on hyporheic conditions in trout redds: reason for concern?

2008 ◽  
Vol 59 (11) ◽  
pp. 1028 ◽  
Author(s):  
Tobias O. Bickel ◽  
Gerard P. Closs
Keyword(s):  
New Zealand ◽  
Surface Water ◽  
Water Exchange ◽  
Potential Surface ◽  
Didymosphenia Geminata ◽  
Exchange Processes ◽  
Significant Difference ◽  
Hydraulic Conditions ◽  
Groundwater Exchange ◽  
The Impact

Didymosphenia geminata (Lyngbye) Schmidt (commonly called didymo) is an invasive diatom and of concern to fisheries managers in North America and more recently New Zealand. Didymo grows in thick mats in several river systems on the South Island of New Zealand, often smothering entire river beds. Salmonid eggs, deposited in gravel nests (redds), depend on constant water exchange across the riverbed to provide oxygen-rich water for development. Thick didymo mats might restrict the flow of oxygen-rich water into spawning gravels, resulting in increased egg mortality and reduced trout recruitment. The present study measured hyporheic hydraulic conditions in trout redds with varying didymo cover in the Clutha River catchment, South Island, New Zealand. Didymo cover had no significant effects on several hydraulic variables (flow into the substrate, hydraulic conductivity and hyporheic oxygen concentration). However, there was a significant difference in the potential surface water–groundwater exchange between sites, suggesting some effect of didymo on hydraulic conditions. Considering the limited number of replicates, the impact of didymo on trout redds in the Clutha River cannot be excluded. The present study highlights the need for further research on the possible effects of didymo on important surface water–groundwater exchange processes.

scholarly journals An Experimental Comparison of the Impact of ‘Warning’ and ‘Health Star Rating’ FoP Labels on Adolescents’ Choice of Breakfast Cereals in New Zealand

Nutrients ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1545 ◽  
Author(s):  
Robert Hamlin ◽  
Benjamin Hamlin
Keyword(s):  
New Zealand ◽  
Experimental Comparison ◽  
Vienna Convention ◽  
Single Star ◽  
Star Rating ◽  
Stop Sign ◽  
Significant Difference ◽  
Nutritional Label ◽  
The Difference ◽  
The Impact

This research investigated the performance of the red, octagonal Vienna Convention traffic ‘STOP’ sign as a front of pack (FoP) warning nutritional label. While the Vienna Convention traffic light system is an established FoP label, the potential of the ‘STOP’ sign in the role has not been investigated. The performance of the ‘STOP’ label was compared with that of a single star (low nutritional value) Australasian Health Star Rating (HSR) label using a fractionally replicated Latin square design. The labels were presented on choice diads of cold breakfast cereal packets. The sample of 240 adolescents aged 16–18 was drawn from a secondary school in the South Island of New Zealand. A large and significant main effect was observed at the p < 0.01 level for the difference between the ’STOP’ sign and the control condition (no nutritional FoP label), and at p < 0.05 for the difference between the HSR and the ‘STOP’ label. There was no significant difference between the HSR FoP and the control condition. A significant non-additivity (interaction) (p < 0.01) was also observed via the fractional replication. The results indicate that the Vienna Convention ‘STOP’ sign is worthy of further research with regard to its potential as an FoP nutritional label.

scholarly journals Sediment properties and CO<sub>2</sub> efflux from intact and cleared temperate mangrove forests

2015 ◽  
Vol 12 (20) ◽  
pp. 6169-6180 ◽  
Author(s):  
R. H. Bulmer ◽  
C. J. Lundquist ◽  
L. Schwendenmann
Keyword(s):  
New Zealand ◽  
Mangrove Forest ◽  
Abiotic Factors ◽  
Co2 Uptake ◽  
Co2 Efflux ◽  
Mangrove Forests ◽  
Sediment Grain Size ◽  
Significant Difference ◽  
Main Factors ◽  
The Impact

Abstract. Temperate mangrove forests in New Zealand have increased in area over recent decades. Expansion of temperate mangroves in New Zealand is associated with perceived loss of other estuarine habitats, and decreased recreational and amenity values, resulting in clearing of mangrove forests. In the tropics, changes in sediment characteristics and carbon efflux have been reported following mangrove clearance. This is the first study in temperate mangrove (Avicennia marina) forests investigating the impact of clearing on sediment CO2 efflux and associated biotic and abiotic factors. Sediment CO2 efflux rates from intact (168.5 ± 45.8 mmol m−2 d−1) and cleared (133.9 ± 37.2 mmol m−2 d−1) mangrove forests in New Zealand are comparable to rates measured in tropical mangrove forests. We did not find a significant difference in sediment CO2 efflux rates between intact and cleared temperate mangrove forests. Pre-shading the sediment for more than 30 min prior to dark chamber measurements was found to have no significant effect on sediment CO2 efflux. This suggests that the continuation of photosynthetic CO2 uptake by biofilm communities was not occurring after placement of dark chambers. Rather, above-ground mangrove biomass, sediment temperature and chlorophyll a concentration were the main factors explaining the variability in sediment CO2 efflux in intact mangrove forests. The main factors influencing sediment CO2 efflux in cleared mangrove forest sites were sediment organic carbon concentration, nitrogen concentration and sediment grain size. Our results show that greater consideration should be given regarding the rate of carbon released from mangrove forest following clearance and the relative contribution to global carbon emissions.

Effect of Rotary Instrument Mineral Oil Lubricant on Osseointegration: A Randomized, Blinded Study in Rabbits

2019 ◽  
Vol 45 (1) ◽  
pp. 12-17
Author(s):  
Arturo Sánchez-Pérez ◽  
Ana Belén Cano-Tovar ◽  
José Javier Martín-de-Llano ◽  
Francisco Javier Sarobe-Oyarzun ◽  
Scott Davis ◽  
...  
Keyword(s):  
New Zealand ◽  
Dental Implants ◽  
Mineral Oil ◽  
Significant Difference ◽  
Blinded Study ◽  
Early Failures ◽  
And Control ◽  
The Impact ◽  
Rotary Instrument ◽  
New Zealand Rabbits

The mechanisms of early failures in dental implant osseointegration are unclear. A possible cause of low levels of bone formation is lubricant contamination on implants during insertion. To explore the impact of lubricant contamination on dental implants, we used 5 New Zealand rabbits and inserted 2 implants per tibia in each animal for a total of 4 implants per animal (20 implants in total). In general, bicorticalization was achieved. The first implant was placed as suggested by the manufacturer with no lubricant used (control). The second implant was placed using a freshly lubricated contra-angle handpiece, which was used only for the test implants. Implant allocation was randomized, and the examining histologist was blinded to the results. All implants were placed by the same surgeon. The animals were maintained in accordance with animal experimentation guidelines. None of the implants failed to osseointegrate. Moreover, no significant difference was observed between the test and control groups. Based on the results of this study, the use of rotary instrument mineral oil lubricant did not jeopardize the osseointegration of dental implants in New Zealand rabbits.

scholarly journals Exposure to COVID-19 Vaccine Hesitancy Is as Impactful as Vaccine Misinformation in Inducing a Decline in Vaccination Intentions in New Zealand: Results from Pre-Post Between-Groups Randomized Block Experiment

2021 ◽  
Vol 6 ◽  
Author(s):  
Jagadish Thaker ◽  
Arun Subramanian
Keyword(s):  
New Zealand ◽  
The Self ◽  
Vaccine Hesitancy ◽  
Survey Experiment ◽  
Factual Information ◽  
Vaccine Acceptance ◽  
Significant Difference ◽  
Nationally Representative ◽  
The Impact ◽  
Block Experiment

While recent studies have investigated how health messages on vaccine characteristics shift public intentions to get a COVID-19 vaccine, a few studies investigate the impact of real-world, widely shared vaccine misinformation on COVID-19 vaccine acceptance. Moreover, there is currently no research that investigates how exposure to hesitancy, as compared to misinformation, is associated with COVID-19 vaccination intentions. Based on data from a nationally representative survey experiment conducted in March 2021 (N = 1,083), exposure to outright COVID-19 vaccine misinformation as well as exposure to vaccine hesitancy induces a decline in COVID-19 vaccination intentions to protect self and to get the vaccine to protect others in New Zealand, compared to factual information from government authorities. Moreover, there is no significant difference in exposure to misinformation or hesitancy in the self-reported change in COVID-19 vaccination intentions. However, respondents are more likely to believe in vaccine hesitancy information and share such information with family and followers compared to misinformation. Implications for research in health communication campaigns on COVID-19 are presented.

scholarly journals Coupling of dynamic hydrological response units and SWAT-MODFLOW to model the impact of vegetation change on hydrological processes in an arid endorheic river watershed

2021 ◽  
Author(s):  
Xin Jin ◽  
Yanxiang Jin
Keyword(s):  
Surface Water ◽  
Water Resources ◽  
Groundwater Recharge ◽  
Vegetation Change ◽  
Hydrological Processes ◽  
Arid Areas ◽  
Hydrological Response ◽  
River Watershed ◽  
Groundwater Exchange ◽  
The Impact

Abstract Vegetation change in arid areas may lead to the redistribution of regional water resources, which can intensify the competition between ecosystems and humans for water resources. Thus, it is necessary to understand the impact of vegetation change on hydrological processes in arid areas. We aimed to accurately model the impact of vegetation change on hydrological processes in an arid endorheic river watershed undergoing revegetation. The middle and lower reaches of the Bayin River basin, China were investigated because this is an area of frequent surface water–groundwater interactions and evident revegetation. A LU-SWAT-MODFLOW model was developed by integrating dynamic hydrological response units with a coupled SWAT-MODFLOW model, which can reflect actual land cover changes in the basin. The results showed that the LU-SWAT-MODFLOW model outperformed the original SWAT-MODFLOW model in simulating human activity impact as well as the leaf area index, evapotranspiration, and groundwater table depth. After regional revegetation, evapotranspiration in different sub-basins increased by 1.5 mm per month and by 6 mm per year. The groundwater recharge increased by 1.27 mm on average per month and 14.02 mm on average per year. Irrigation for the recovered vegetation strongly affected the groundwater recharge. In addition, the direction and amount of surface water–groundwater exchange considerably changed in areas where revegetation involved converting low-coverage grassland and bare land to forestland. In areas where revegetation involved converting farmland to forestland, the transition had a weak effect on the direction and amount of surface water–groundwater exchange.

scholarly journals Evaluation of the impact of disinfection processes on the formation of biofilms in potable surface water distribution systems

1998 ◽  
Vol 38 (8-9) ◽  
pp. 283-289 ◽  
Author(s):  
Maggy N. B. Momba ◽  
T. E. Cloete ◽  
S. N. Venter ◽  
R. Kfir
Keyword(s):  
Hydrogen Peroxide ◽  
Surface Water ◽  
Biofilm Formation ◽  
Distribution Systems ◽  
Water Distribution ◽  
Water Distribution Systems ◽  
Residual Effect ◽  
Viable Count ◽  
Significant Difference ◽  
The Impact

In this study, surface water was used to evaluate the impact of disinfection processes (chlorination, chloramination, ozonation, UV irradiation and hydrogen peroxide) on biofilm formation in potable water distribution systems. Biofilm formation was obvious, even in the presence of residual disinfectant concentrations (16.5 mgl−1 hydrogen peroxide, 1 mg−1 monochloramine, 0.2 mgl−1 free chlorine) within the first day after disinfection in the laboratory scale unit. The yield in viable count was higher on stainless steel coupons than on cement coupons within the first 8 days. Viable bacteria numbers on cement coupons were similar (±2 log cfu.cm−2) in chlorinated, ozonated and in the control. Biofilm formation was related to the depletion of residual disinfectant concentration. Monochloramine and hydrogen peroxide had a longer residual effect controlling growth of biofilm cells in the system for a longer period before regrowth occurred. Once no residual concentrations could be detected there was no significant difference between the viable bacterial counts on any of the coupons in the various systems.

scholarly journals Vertical surface water-groundwater exchange processes within a headwater floodplain induced by experimental floods

2016 ◽  
Vol 30 (21) ◽  
pp. 3770-3787 ◽  
Author(s):  
Erich T. Hester ◽  
Christopher R. Guth ◽  
Durelle T. Scott ◽  
Charles N. Jones
Keyword(s):  
Surface Water ◽  
Vertical Surface ◽  
Exchange Processes ◽  
Groundwater Exchange

scholarly journals Damming Weakens the Groundwater and Surface Water Exchange and Its Nitrate Removal in Semi-arid Prairie Rivers

2022 ◽  
Author(s):  
Jing Huang ◽  
Xixi Lu ◽  
Xin Luo ◽  
Haizhu Hu ◽  
Jiu Jimmy Jiao
Keyword(s):  
Surface Water ◽  
Water Exchange ◽  
Nitrate Removal ◽  
Vital Role ◽  
Eurasian Steppe ◽  
Hydraulic Method ◽  
Exchange Processes ◽  
Negative Effect ◽  
Tracer Methods ◽  
Semi Arid

Abstract Surface water (SW)-Groundwater (GW) exchange plays a vital role in a prairie aquatic system and the biogeochemical cycling in such a system. Considering the inadequate understanding of damming on SW-GW exchange, a damming prairie river in Southeast Eurasian steppe was chosen to investigate variations of the SW-GW exchange and its influences on the fate of nitrate (NO3-). Both hydraulic and hydrochemical methods were applied to precisely depict the daily and seasonal exchange processes. The upstream and downstream reaches of the dam were observed to be upwelling and downwelling conditions respectively within a hydrologic year. Results obtained from multiple tracer methods and hydraulic method indicate that damming contributed to transfer the stream from the upwelling to the downwelling condition and weaken the SW-GW exchange in the downstream. The patterns of SW-GW exchange modulated the NO3- uptake or production between the SW and the GW. NO3- was mainly removed in the SW-GW exchange zone (SW-GW EZ) of the upwelling segment, while produced in the downwelling segment. Both the removal and production of NO3- were enhanced during snowmelt period, which might be an active period for the SW-GW exchange and NO3- fate. This study underscores the negative effect of damming on the SW-GW exchange and accompanied NO3- removal in prairie river systems.

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