title: The potential for Charophyte re-establishment in large, shallow, eutrophic lakes with special reference to Lake Waikare, New Zealand.

authors: Hopkins, Aareka

subjects: lake restoration

abstract: Lake Waikare is a large, shallow eutrophic lake devoid of submerged macrophytes. I investigated potential methods for re-establishing submerged macrophytes in the lake. Specifically, I subjected charophyte (Chara corallina) plantlets to two treatments of exposure in the lake (in areas exposed and sheltered from wind) to test for survival and growth under these conditions, and inside and outside fish exclosures to test for growth and survival in the presence of fish. 

While plantlets grew outside the exclosures in winter, their accumulated biomass over 21 days was less than protected plantlets. In winter, the accumulated biomass was lower outside than inside exclosures (by ~40%) at the sheltered site and was lower outside than inside exclosures (by 43%) at the exposed site. Overall, growth rates in winter were higher at the sheltered site (compared to the exposed site) by ~7%. In summer, charophyte accumulated biomass inside the exclosures increased by 85%, while at the sheltered site accumulated biomass increased by 58%. Outside the exclosures in summer the plantlets were completely removed at both sites. Overall, growth rates where higher at the exposed site than the sheltered site by 31%. Fish were responsible for the partial removal of plantlets in winter and total removal of plantlets in summer, and therefore affect the survival and growth of charophytes in Lake Waikare. The embayment at the sheltered site provides the best location in winter for re-establishment of charophytes from oospores because better growth rates were obtained there, and its sheltered location provides protection from severe wave action found at the exposed site. Oospores did not germinate after being submersed in the lake for 90 days due to heavy sedimentation.

To induce an improvement in the present light climate, Alum was tested to determine its effectiveness and longevity for settling lake sediments to allow charophytes to establish and grow. Examining the settling rates of Lake Waikare sediments and water treated with Alum over a range of suspended sediment concentrations and time intervals, sediments settled faster with Alum than without for at least 15 days (at 200 g l^1 suspended sediment concentration) and it remained active to 60 days but at reduced effectiveness. At the other concentrations tested (100 g l^1 and 300 g l^1 suspended sediment concentration), Alum responses were insignificant.

An improved light climate achieved by fish removal or Alum treatment will likely not be sufficient to permit the re-establishment of submerged macrophytes due to the turbid, algal-dominated state of the lake. The present nutrient and sediment levels, wave climate and fish influence must be mitigated so charophyte plantlets can be established.

text: The potential for Charophyte re-establishment in large, shallow, eutrophic lakes with special reference to Lake Waikare, New Zealand. Lake Waikare is a large, shallow eutrophic lake devoid of submerged macrophytes. I investigated potential methods for re-establishing submerged macrophytes in the lake. Specifically, I subjected charophyte (Chara corallina) plantlets to two treatments of exposure in the lake (in areas exposed and sheltered from wind) to test for survival and growth under these conditions, and inside and outside fish exclosures to test for growth and survival in the presence of fish. 

While plantlets grew outside the exclosures in winter, their accumulated biomass over 21 days was less than protected plantlets. In winter, the accumulated biomass was lower outside than inside exclosures (by ~40%) at the sheltered site and was lower outside than inside exclosures (by 43%) at the exposed site. Overall, growth rates in winter were higher at the sheltered site (compared to the exposed site) by ~7%. In summer, charophyte accumulated biomass inside the exclosures increased by 85%, while at the sheltered site accumulated biomass increased by 58%. Outside the exclosures in summer the plantlets were completely removed at both sites. Overall, growth rates where higher at the exposed site than the sheltered site by 31%. Fish were responsible for the partial removal of plantlets in winter and total removal of plantlets in summer, and therefore affect the survival and growth of charophytes in Lake Waikare. The embayment at the sheltered site provides the best location in winter for re-establishment of charophytes from oospores because better growth rates were obtained there, and its sheltered location provides protection from severe wave action found at the exposed site. Oospores did not germinate after being submersed in the lake for 90 days due to heavy sedimentation.

To induce an improvement in the present light climate, Alum was tested to determine its effectiveness and longevity for settling lake sediments to allow charophytes to establish and grow. Examining the settling rates of Lake Waikare sediments and water treated with Alum over a range of suspended sediment concentrations and time intervals, sediments settled faster with Alum than without for at least 15 days (at 200 g l^1 suspended sediment concentration) and it remained active to 60 days but at reduced effectiveness. At the other concentrations tested (100 g l^1 and 300 g l^1 suspended sediment concentration), Alum responses were insignificant.

An improved light climate achieved by fish removal or Alum treatment will likely not be sufficient to permit the re-establishment of submerged macrophytes due to the turbid, algal-dominated state of the lake. The present nutrient and sediment levels, wave climate and fish influence must be mitigated so charophyte plantlets can be established.

year: 2006

title: Real interest rates, inflation and open economy: A regime-switching perspective on Australia and New Zealand

authors: Holmes, Mark J.

subjects: stationary

abstract: We investigate the time-series properties of Australian and New Zealand real interest rates within a Markov-switching framework. This enables us to identify characteristics in real interest rate behavior hitherto unacknowledged. We find that rates switch between alternative stationary regimes characterized by differing means, speeds of mean-reversion and volatility. For New Zealand, high rates of inflation increase the probability of remaining in a regime characterized by a faster speed of adjustment. Further application of this methodology considers the real interest rate differential between Australia and New Zealand and points to differing regimes based on volatility rather than persistence.

text: Real interest rates, inflation and open economy: A regime-switching perspective on Australia and New Zealand We investigate the time-series properties of Australian and New Zealand real interest rates within a Markov-switching framework. This enables us to identify characteristics in real interest rate behavior hitherto unacknowledged. We find that rates switch between alternative stationary regimes characterized by differing means, speeds of mean-reversion and volatility. For New Zealand, high rates of inflation increase the probability of remaining in a regime characterized by a faster speed of adjustment. Further application of this methodology considers the real interest rate differential between Australia and New Zealand and points to differing regimes based on volatility rather than persistence.

year: 2009

title: Ngati Rahiri versus Ngati Tamatera

authors: Hart, Philip

abstract: Conflict between Ngati Tamatera, of Ohinemuri, and Ngati Rahiri, of Te Aroha, was provoked by the latter believing that members of other hapu had received money for the Aroha Block to which they were not entitled. In addition, the two hapu disagreed over the block’s northern boundary. In early 1877 Ngati Rahiri threatened violence and even fired over the heads of several rangatira passing through their land, thereby challenging their right to intrude on it. In response, Ngati Tamatera, with the assistance of Ngati Koi, blocked the road to Te Aroha and also the Waihou River against Ngati Rahiri, although they permitted Pakeha to pass. Pakeha took a relaxed attitude to the conflict, not expecting any real battles occurring during a squabble they understood to have been caused by members of an inferior hapu having their names wrongly included in Crown grants.
After Ngati Tamatera erected two small and unimpressive pa to block both road and river, Ngati Rahiri retaliated by constructing a similarly unimpressive pa at Omahu, their settlement at Te Aroha. Apart from much posturing, the only actions taken were Ngati Tamatera sending back to Omahu an aged woman who had come down the river in a canoe and Ngati Rahiri stealing pigs and peaches and firing shots near a settlement. The Native Minister and various officials, notably James Mackay, intervened to resolve the conflict, which was ended with a reconciliation initiated by Ngati Tamatera and formalized by a large meeting of both hapu at Omahu.
Once this quarrel was settled, negotiations to enable the Crown to purchase the Aroha Block were resumed.

text: Ngati Rahiri versus Ngati Tamatera Conflict between Ngati Tamatera, of Ohinemuri, and Ngati Rahiri, of Te Aroha, was provoked by the latter believing that members of other hapu had received money for the Aroha Block to which they were not entitled. In addition, the two hapu disagreed over the block’s northern boundary. In early 1877 Ngati Rahiri threatened violence and even fired over the heads of several rangatira passing through their land, thereby challenging their right to intrude on it. In response, Ngati Tamatera, with the assistance of Ngati Koi, blocked the road to Te Aroha and also the Waihou River against Ngati Rahiri, although they permitted Pakeha to pass. Pakeha took a relaxed attitude to the conflict, not expecting any real battles occurring during a squabble they understood to have been caused by members of an inferior hapu having their names wrongly included in Crown grants.
After Ngati Tamatera erected two small and unimpressive pa to block both road and river, Ngati Rahiri retaliated by constructing a similarly unimpressive pa at Omahu, their settlement at Te Aroha. Apart from much posturing, the only actions taken were Ngati Tamatera sending back to Omahu an aged woman who had come down the river in a canoe and Ngati Rahiri stealing pigs and peaches and firing shots near a settlement. The Native Minister and various officials, notably James Mackay, intervened to resolve the conflict, which was ended with a reconciliation initiated by Ngati Tamatera and formalized by a large meeting of both hapu at Omahu.
Once this quarrel was settled, negotiations to enable the Crown to purchase the Aroha Block were resumed.

year: 2016