title: Acetylene reduction associated with zostera novazelandica Setch. and Spartina alterniflora Loisel., in Whangateau harbour, North Island, New Zealand

authors: Hicks, Brendan J.

subjects: biology

abstract: Nitrogen fixation (acetylene reduction) was investigated in Zostera novazelandica Setch. and Spartina alterniflora Loisel., in the North Island of New Zealand. Moderate rates of acetylene reduction were found in sediments in which plants were growing (means ± 95% confidence limit: 15.2 ± 2.8 |jmol C2H4 nrr2 h~l for Zostera and 24.7 ± 4.6 |amol C2H4 m~2 h"1 for Spartina). Activity was closely correlated with the dry weight of root; (r2 = 0.65, N = 15 for Zostera, and r2 = 0.85, A' =10 for Spartina). Sediment close to the plant beds, but without plants, exhibited only low rates of acetylene reduction (2.9 ± 2.2 and 4.5 ± l.OjLtmol C2H4 m~2 h"1, respectively). Sediments associated with Z. novazelandica and S. alterniflora in New Zealand exhibit moderate rates of nitrogenase activity compared to rates found in other countries. N fixation may contribute significantly to the nutrition of these plants in New Zealand estuaries.

text: Acetylene reduction associated with zostera novazelandica Setch. and Spartina alterniflora Loisel., in Whangateau harbour, North Island, New Zealand Nitrogen fixation (acetylene reduction) was investigated in Zostera novazelandica Setch. and Spartina alterniflora Loisel., in the North Island of New Zealand. Moderate rates of acetylene reduction were found in sediments in which plants were growing (means ± 95% confidence limit: 15.2 ± 2.8 |jmol C2H4 nrr2 h~l for Zostera and 24.7 ± 4.6 |amol C2H4 m~2 h"1 for Spartina). Activity was closely correlated with the dry weight of root; (r2 = 0.65, N = 15 for Zostera, and r2 = 0.85, A' =10 for Spartina). Sediment close to the plant beds, but without plants, exhibited only low rates of acetylene reduction (2.9 ± 2.2 and 4.5 ± l.OjLtmol C2H4 m~2 h"1, respectively). Sediments associated with Z. novazelandica and S. alterniflora in New Zealand exhibit moderate rates of nitrogenase activity compared to rates found in other countries. N fixation may contribute significantly to the nutrition of these plants in New Zealand estuaries.

year: 1990

title: Acoustic and radio-transmitter retention in common carp (Cyprinus carpio) in New Zealand

authors: Daniel, Adam Joshua

subjects: surgical implant

abstract: Common carp (Cyprinus carpio) are notoriously difficult to monitor in water temperatures above 20◦C using telemetry owing to transmitter expulsion. To reduce transmitter loss, radio transmitters were anchored to the pelvic girdle and a polymer coating was applied to acoustic transmitters to reduce tissue irritation in two tank trials. Ten dummy transmitters were surgically implanted in each of four groups of adult koi carp, a highly coloured strain of C. carpio. Water temperatures ranged between 7 and 24◦C. After 365 days, the control and test groups of each trial had similar expulsion rates (P≥0.30; two-tailed Fisher’s exact probability test). Expulsion rates for uncoated acoustic transmitters were 60% (n=6), coated acoustic transmitters 50% (n=5), unanchored radio transmitters 60% (n=6) and anchored radio transmitters 90% (n=9). Expulsions occurred 15–362 days after implantation as a result of ulcers at or near the surgical wound. Bacterial infection of the wound appears to be the primary mechanism for transmitter expulsion.

text: Acoustic and radio-transmitter retention in common carp (Cyprinus carpio) in New Zealand Common carp (Cyprinus carpio) are notoriously difficult to monitor in water temperatures above 20◦C using telemetry owing to transmitter expulsion. To reduce transmitter loss, radio transmitters were anchored to the pelvic girdle and a polymer coating was applied to acoustic transmitters to reduce tissue irritation in two tank trials. Ten dummy transmitters were surgically implanted in each of four groups of adult koi carp, a highly coloured strain of C. carpio. Water temperatures ranged between 7 and 24◦C. After 365 days, the control and test groups of each trial had similar expulsion rates (P≥0.30; two-tailed Fisher’s exact probability test). Expulsion rates for uncoated acoustic transmitters were 60% (n=6), coated acoustic transmitters 50% (n=5), unanchored radio transmitters 60% (n=6) and anchored radio transmitters 90% (n=9). Expulsions occurred 15–362 days after implantation as a result of ulcers at or near the surgical wound. Bacterial infection of the wound appears to be the primary mechanism for transmitter expulsion.

year: 2009

title: Lake Rotokakahi water quality update 1990-2011

authors: Butterworth, Joseph

subjects: Lake Rotokakahi

abstract: Lake Rotokakahi is an Iwi-owned lake administered by the Lake Rotokakahi Board of Control on Behalf of lake owners who are descendants from the Ngāti Tumatawera and Tūhourangi hapū of Te Arawa. It is mesotrophic (moderate water quality) lake with an area of 4.4 km² comprised of exotic forestry (57.1%), pasture (26.3%) and regenerating indigenous forest/scrub (16.6%).

text: Lake Rotokakahi water quality update 1990-2011 Lake Rotokakahi is an Iwi-owned lake administered by the Lake Rotokakahi Board of Control on Behalf of lake owners who are descendants from the Ngāti Tumatawera and Tūhourangi hapū of Te Arawa. It is mesotrophic (moderate water quality) lake with an area of 4.4 km² comprised of exotic forestry (57.1%), pasture (26.3%) and regenerating indigenous forest/scrub (16.6%).

year: 2012