title: Colour classification of 1486 lakes across a wide range of optical water types

authors: Lehmann, Moritz K.

subjects: lakes

abstract: Remote sensing by satellite-borne sensors presents a significant opportunity to enhance the spatio-temporal coverage of environmental monitoring programmes for lakes, but the estimation of classic water quality attributes from inland water bodies has not reached operational status due to the difficulty of discerning the spectral signatures of optically active water constituents. Determination of water colour, as perceived by the human eye, does not require knowledge of inherent optical properties and therefore represents a generally applicable remotely-sensed water quality attribute. In this paper, we implemented a recent algorithm for the retrieval of colour parameters (hue angle, dominant wavelength) and derived a new correction for colour purity to account for the spectral bandpass of the Landsat 8 Operational Land Imager (OLI). We used this algorithm to calculate water colour on almost 45,000 observations over four years from 1486 lakes from a diverse range of optical water types in New Zealand. We show that the most prevalent lake colours are yellow-orange and blue, respectively, while green observations are comparatively rare. About 40% of the study lakes show transitions between colours at a range of time scales, including seasonal. A preliminary exploratory analysis suggests that both geo-physical and anthropogenic factors, such as catchment land use, provide environmental control of lake colour and are promising avenues for future analysis.

text: Colour classification of 1486 lakes across a wide range of optical water types Remote sensing by satellite-borne sensors presents a significant opportunity to enhance the spatio-temporal coverage of environmental monitoring programmes for lakes, but the estimation of classic water quality attributes from inland water bodies has not reached operational status due to the difficulty of discerning the spectral signatures of optically active water constituents. Determination of water colour, as perceived by the human eye, does not require knowledge of inherent optical properties and therefore represents a generally applicable remotely-sensed water quality attribute. In this paper, we implemented a recent algorithm for the retrieval of colour parameters (hue angle, dominant wavelength) and derived a new correction for colour purity to account for the spectral bandpass of the Landsat 8 Operational Land Imager (OLI). We used this algorithm to calculate water colour on almost 45,000 observations over four years from 1486 lakes from a diverse range of optical water types in New Zealand. We show that the most prevalent lake colours are yellow-orange and blue, respectively, while green observations are comparatively rare. About 40% of the study lakes show transitions between colours at a range of time scales, including seasonal. A preliminary exploratory analysis suggests that both geo-physical and anthropogenic factors, such as catchment land use, provide environmental control of lake colour and are promising avenues for future analysis.

year: 2018

title: Boat electrofishing survey of the Waimapu and Kopurererua streams, Bay of Plenty, Waitara River, and a pond at Mokoia, Taranaki

authors: Hicks, Brendan J.

subjects: New Zealand

abstract: We conducted boat electrofishing surveys at four sites to establish the presence of, and to remove, koi carp (Cyprinus carpio). We fished the lower Waimapu Stream, Bay of Plenty, on 15 April and 14 June 2005, and the adjacent Kopurererua Stream on 15 June 2005. We caught and removed two large koi carp ( a 7.9 kg male and a 6.9 kg female) from the Waimapu Stream in 15 April, but saw no other koi carp in 3.2-km reaches of both streams on 14-15 June. We did, however, catch a wide diversity of native fish species, including common smelt, shortfin and longfin eels, yelloweye mullet, brown and rainbow trout, giant bullies, and black flounder. We also caught a lamprey macrophthalmia in the Waimapu Stream.
No koi carp were found in a 2.4-km tidal reach of the Waitara River, northern Taranaki, on 8 June 2005, but we did catch a sparse native fish assemblage of adult inanga, shortfin eels, a few common smelt, black flounder, yelloweye mullet, and a 200-mm giant bully.
We caught and killed 16 large koi carp (total weight 58.5 kg) from a pond on private farmland near Mokoia, southern Taranaki, on 9 June 2005. This pond had a perimeter of 215 m, a surface area of 951 m², and maximum depth of 2.0 m. These fish were removed by depletion fishing in 7 circuits of the pond. We caught 9, 3, 1, 1, 1, 1, and 0 carp in successive circuits. The Zippin method of population estimation (±95% confidence interval) suggests that there were 16±1 koi carp in the pond, so it is possible that we eradicated all of the koi. All the carp were the same age and no juveniles were found, so it appears that the carp had not breed successfully in this pond.

text: Boat electrofishing survey of the Waimapu and Kopurererua streams, Bay of Plenty, Waitara River, and a pond at Mokoia, Taranaki We conducted boat electrofishing surveys at four sites to establish the presence of, and to remove, koi carp (Cyprinus carpio). We fished the lower Waimapu Stream, Bay of Plenty, on 15 April and 14 June 2005, and the adjacent Kopurererua Stream on 15 June 2005. We caught and removed two large koi carp ( a 7.9 kg male and a 6.9 kg female) from the Waimapu Stream in 15 April, but saw no other koi carp in 3.2-km reaches of both streams on 14-15 June. We did, however, catch a wide diversity of native fish species, including common smelt, shortfin and longfin eels, yelloweye mullet, brown and rainbow trout, giant bullies, and black flounder. We also caught a lamprey macrophthalmia in the Waimapu Stream.
No koi carp were found in a 2.4-km tidal reach of the Waitara River, northern Taranaki, on 8 June 2005, but we did catch a sparse native fish assemblage of adult inanga, shortfin eels, a few common smelt, black flounder, yelloweye mullet, and a 200-mm giant bully.
We caught and killed 16 large koi carp (total weight 58.5 kg) from a pond on private farmland near Mokoia, southern Taranaki, on 9 June 2005. This pond had a perimeter of 215 m, a surface area of 951 m², and maximum depth of 2.0 m. These fish were removed by depletion fishing in 7 circuits of the pond. We caught 9, 3, 1, 1, 1, 1, and 0 carp in successive circuits. The Zippin method of population estimation (±95% confidence interval) suggests that there were 16±1 koi carp in the pond, so it is possible that we eradicated all of the koi. All the carp were the same age and no juveniles were found, so it appears that the carp had not breed successfully in this pond.

year: 2005

title: Mokopuna rising: Developing a best practice for early intervention in whanau violence

authors: Cooper, Erana

subjects: Maori

abstract: In a very difficult meeting, an extremely unpleasant man was concerned about the possible loss of his power and the continuation of his plans and dreams for the future. And I said, yeah well, you should be worried, because according to your philosophy, when you’re dead, you’re dead. But when I’m dead, my mokopuna will be rising. (Personal Communication, Rob Cooper, 2007) 
“Mokopuna Rising” is about claiming space for Maori to define best practice for reducing and avoiding whanau violence1 It is research in progress towards a PhD, being carried out with the Ngati Hine Health Trust, in Te Taitokerau (Northland).

text: Mokopuna rising: Developing a best practice for early intervention in whanau violence In a very difficult meeting, an extremely unpleasant man was concerned about the possible loss of his power and the continuation of his plans and dreams for the future. And I said, yeah well, you should be worried, because according to your philosophy, when you’re dead, you’re dead. But when I’m dead, my mokopuna will be rising. (Personal Communication, Rob Cooper, 2007) 
“Mokopuna Rising” is about claiming space for Maori to define best practice for reducing and avoiding whanau violence1 It is research in progress towards a PhD, being carried out with the Ngati Hine Health Trust, in Te Taitokerau (Northland).

year: 2008