Combating hypoxia/anoxia is an increasingly common need for restoring natural waters suffering from eutrophication. Oxygen nanobubble modified natural particles were investigated for mitigating hypoxia/anoxia at the sediment-water interface (SWI) in a simulated column experiment. By adding oxygen nanobubble modified zeolites (ONMZ) and local soils (ONMS), the oxygen nanobubble concentrations (10-10 particles/mL) were several orders of magnitude higher in the water than the original water solution (10 particles/mL) within 24 h. In the column experiment, an oxygen-locking surface sediment layer was formed after capping with ONMZ and ONMS particles. The synergy of diffusion of oxygen nanobubbles and retention of oxygen in this layer contributes to both the increase of DO and reversal of hypoxic conditions. The overlying water had significantly higher dissolved oxygen (DO) values (4-7.5 mg/L) over the experimental period of 127 days in ONMZ and ONMS compared with the control systems (around 1 mg/L). Moreover, the oxidation-reduction potential (ORP) was reversed from -200 mV to 180-210 mV and maintained positive values for 89 days in ONMZ systems. In the control systems, ORP was consistently negative and decreased from -200 mV to -350 mV. The total phosphorus (TP) flux from sediment to water across the SWI was negative in the ONMZ and ONMS treated systems, but positive in the control system, indicating the sediment could be switched from TP source to sink. The oxygen-locking capping layer was crucial in preventing oxygen consumption caused by the reduced substances released from the anoxic sediment. The study outlines a potentially promising technology for mitigating sediment anoxia and controlling nutrient release from sediments, which could contribute significantly to addressing eutrophication and ecological restoration.

A total of 566 koi carp (Cyprinus carpio) from the lower Waikato region were aged from scales and opercular bones, and growth was modelled with the von Bertalanffy growth function. There was no difference in growth rate between male and female carp. Growth of koi carp between zero and 3 years of age was lower than that of common carp in europe and Australia. however, after 5 years of age the growth of koi carp was higher than that of common carp in europe, but still below that of carp in Australia. males rarely lived in excess of 8 years, whereas females lived to 12 years. mean total fecundity calculated from 44 running-ripe females was 299 000 oocytes (±195 600 sd) (range 29 800-771 000). relative fecundity ranged from 19 300 to 216 000 oocytes kg-1 total body weight, with a mean of 97 200 (±35 000 sd) oocytes kg-1. Feral koi carp in the Waikato are capable of multiple spawnings within their lifetimes. Within a spawning season, Waikato populations of feral koi carp contained females that spawned once, and females that had the potential to have spawned repeatedly. Female gonadosomatic index (Gsi) varied with season and was negatively related to water temperature.

No abstract

A new automated monitoring device for small carnivores, the Scentinel®, is a ‘smart’ tracking tunnel. It records time, date, weight and a digital photograph of every animal visiting it, and stores the data to be downloaded on command. This paper describes a field trial aiming, first, to verify the Scentinel’s species identifications against those given by footprint tracking papers, and then to compare the efficacy of routine monitoring with the Scentinel against standard tunnel tracking methods. In February–April 2005 we identified to species 98% of 1559 visiting animals, mainly hedgehogs (Erinaceus europaeus), ferrets (Mustela furo), cats (Felis catus) and rats (Rattus rattus and R. norvegicus) in 1718 Scentinel-nights. In May–June 2005 we set up three monitoring lines 1 km apart, each with 10 tracking tunnels and two Scentinels. We recorded 656 visits by ship rats (Rattus rattus), 88% of them on only one of the three lines, in 198 Scentinel-nights (over 5 weeks). The 30 footprint tracking tunnels set intermittently (360 trap-nights) recorded high (70–100%) tracking rates on all lines. The presence of a stoat (Mustela erminea) was detected by both methods, but earlier by Scentinels than by tracking tunnels. These results confirm that it is possible to use automated devices to record detailed monitoring data on small carnivores in remote areas over long periods, unaffected by interference or bait loss from common non-target species.