title: Long-term variations in fish assemblage, macrophyte community, and water quality in Lake Rotoroa (Hamilton Lake)

authors: Law, Duncan Robert Mckenzie

abstract: Lake Rotoroa (37º48’S, 175º16’E) is a small, shallow, polymictic lake located on the western side of Hamilton City. The lake covers an area of 0.54 km2 with a mean depth of 2.4 m, catchment and riparian margins have been significantly modified into a suburban park-like setting. Due to its urban location and recreational value, exotic flora and fauna have been intentionally and unintentionally introduced. This has resulted in fluctuations in water quality and changes in phytoplankton, fish, and macrophyte assemblages over the past 60 years. The overall aim of this thesis is to summarise the fluctuations in water quality and macrophyte community of Lake Rotoroa associated with introduction of exotic species, and to develop a general understanding of the ecosystem response. This study involved collating and analysing available information on fish assemblages, macrophyte community, and water quality in Lake Rotoroa. Data from nine fish surveys undertaken between 1976 and 2012 has been combined. Water quality and macrophyte data was supplied by NIWA, who have undertaken monitoring for Hamilton City Council as part of the national lakes monitoring programme.

Fishing methods have varied from gill, trap, and fyke netting between 1976 and 2001, with boat electrofishing surveys between 2003 and 2012. Lake Rotoroa has a relatively diverse freshwater fish fauna, comprising two native and six exotic fish species. The fish assemblage is now dominated by the native shortfin eel (Anguilla australis), European perch (Perca fluviatilis), brown bullhead catfish (Ameiurus nebulosus), and tench (Tinca tinca), with low densities of rudd (Scardinius erythrophthalmus) and goldfish (Carassius auratus). Fish density and biomass have varied throughout the survey period, to some extent related to the environmental conditions and macrophyte cover. 

Macrophyte coverage and water quality have undergone considerable changes in the last 30 years, with the collapses of macrophytes stimulating decreases in water quality and increased perch abundance. In 1990, the macrophyte community collapsed with an associated release of nutrients into the water column, causing the lake to become supertrophic. Between 1992 and 2010, water quality improved, with a decrease phosphorus concentrations that apparently limited phytoplankton biomass and improved water clarity. This allowed macrophytes to recolonise the lake to 30% lake bed coverage in 2005 and a consequent improvement from supertrophic to a eutrophic state. Since 2009, the macrophyte community has undergone another collapse, with only a few clumps of native charophytes and Egeria densa present in 2011. The reduction of macrophytes has been accompanied by a decrease in water clarity. The collapse has been attributed to disturbance by grazing from the herbivorous rudd and foraging benthic feeding fish, although other stresses such as decreased water clarity and microcystins may also have had an influence. 

Further research is needed on the selectivity between passive and active fish capture methods used to allow accurate comparisons between the two methods. This will allow for density and biomass estimates to be made for the passive fishing methods previously used and allow greater insight into changes in abundance of fish populations in Lake Rotoroa.

text: Long-term variations in fish assemblage, macrophyte community, and water quality in Lake Rotoroa (Hamilton Lake) Lake Rotoroa (37º48’S, 175º16’E) is a small, shallow, polymictic lake located on the western side of Hamilton City. The lake covers an area of 0.54 km2 with a mean depth of 2.4 m, catchment and riparian margins have been significantly modified into a suburban park-like setting. Due to its urban location and recreational value, exotic flora and fauna have been intentionally and unintentionally introduced. This has resulted in fluctuations in water quality and changes in phytoplankton, fish, and macrophyte assemblages over the past 60 years. The overall aim of this thesis is to summarise the fluctuations in water quality and macrophyte community of Lake Rotoroa associated with introduction of exotic species, and to develop a general understanding of the ecosystem response. This study involved collating and analysing available information on fish assemblages, macrophyte community, and water quality in Lake Rotoroa. Data from nine fish surveys undertaken between 1976 and 2012 has been combined. Water quality and macrophyte data was supplied by NIWA, who have undertaken monitoring for Hamilton City Council as part of the national lakes monitoring programme.

Fishing methods have varied from gill, trap, and fyke netting between 1976 and 2001, with boat electrofishing surveys between 2003 and 2012. Lake Rotoroa has a relatively diverse freshwater fish fauna, comprising two native and six exotic fish species. The fish assemblage is now dominated by the native shortfin eel (Anguilla australis), European perch (Perca fluviatilis), brown bullhead catfish (Ameiurus nebulosus), and tench (Tinca tinca), with low densities of rudd (Scardinius erythrophthalmus) and goldfish (Carassius auratus). Fish density and biomass have varied throughout the survey period, to some extent related to the environmental conditions and macrophyte cover. 

Macrophyte coverage and water quality have undergone considerable changes in the last 30 years, with the collapses of macrophytes stimulating decreases in water quality and increased perch abundance. In 1990, the macrophyte community collapsed with an associated release of nutrients into the water column, causing the lake to become supertrophic. Between 1992 and 2010, water quality improved, with a decrease phosphorus concentrations that apparently limited phytoplankton biomass and improved water clarity. This allowed macrophytes to recolonise the lake to 30% lake bed coverage in 2005 and a consequent improvement from supertrophic to a eutrophic state. Since 2009, the macrophyte community has undergone another collapse, with only a few clumps of native charophytes and Egeria densa present in 2011. The reduction of macrophytes has been accompanied by a decrease in water clarity. The collapse has been attributed to disturbance by grazing from the herbivorous rudd and foraging benthic feeding fish, although other stresses such as decreased water clarity and microcystins may also have had an influence. 

Further research is needed on the selectivity between passive and active fish capture methods used to allow accurate comparisons between the two methods. This will allow for density and biomass estimates to be made for the passive fishing methods previously used and allow greater insight into changes in abundance of fish populations in Lake Rotoroa.

year: 2012

title: In search of unity: Learning from headstones

authors: Mullan, Fintan

subjects: Irish history

abstract: This paper explores a small anomaly of Irish history. Despite the large-scale re-organisation of the state at the beginning of the 18th century in Ireland, and the divided society created by the civil authorities, the old parish cemetery escaped this segregation and continued to be used by all members of the community, irrespective of Christian denomination. This came to be regarded as a right which, if not actually protected by law, was at least protected by custom. For this reason, researchers and local communities have a rich resource from which they can learn about the past and draw lessons for the future.

text: In search of unity: Learning from headstones This paper explores a small anomaly of Irish history. Despite the large-scale re-organisation of the state at the beginning of the 18th century in Ireland, and the divided society created by the civil authorities, the old parish cemetery escaped this segregation and continued to be used by all members of the community, irrespective of Christian denomination. This came to be regarded as a right which, if not actually protected by law, was at least protected by custom. For this reason, researchers and local communities have a rich resource from which they can learn about the past and draw lessons for the future.

year: 2003-02

title: Ungentlemanly warfare: The impact of irregular warfare on military strategy in the New Zealand Wars

authors: Foy, Rhys

subjects: New Zealand Wars

abstract: ‘Ungentlemanly Warfare’ examines the impact of irregular warfare on strategic thinking in the New Zealand Wars (1845–1872). Britain entered the period as an eighteenth-century force reliant on European methods of war. In contrast, Māori were an experienced bushfighting force depleted on manpower but experiencing a period of military innovation. This interaction led to an important exchange of strategic ideology and methods.  
This thesis tracks how Māori, British, and colonial forces developed and exchanged irregular warfare practices across three regions and time periods. The Northern War exposed the shortcomings of conventional military conduct. Māori leadership altered their strategic approach and pursued a strategy of elastic offence. In contrast, British leadership persisted with their ineffective conventional means of warfare. In the Waikato War, British strategy was influenced by the success of colonial irregulars. British strategic and operational methods changed with the inclusion of multi-echelon warfare and the indirect approach. Kīngitanga leadership improved their combat capacity through guerrilla warfare, decentralised command, and a grand strategy of elastic offence. The Taranaki and West Coast campaigns highlighted the relationship between the use of irregular warfare and military success in New Zealand. Both sides experienced success and failure across numerous conflicts, the defining factor being the active use of irregular warfare. These case studies reveal the significance of irregular warfare strategies and tactics to military success in colonial New Zealand. They also reveal opportunities and challenges to military adaptation in Māori, British, and colonial martial cultures of the nineteenth century. 
 ‘Ungentlemanly Warfare’ provides a unique approach to the examination of the New Zealand Wars conflict. It is an operational history that draws upon methods and aspects of the ‘war and society’ approach to military history, especially the use of Māori scholarship, evidence, and theory. The thesis’ chapters consider strategic and tactical decision-making across the numerous conflicts within the period. To do so, I provide close readings of primary evidence, including military communication and reports, early histories, and first-person accounts, to identify the roles of irregular warfare and strategic adaptions in the New Zealand Wars. 
	‘Ungentlemanly Warfare’ analyses the impact of irregular warfare on the strategic thinking of military leaders within the New Zealand Wars. I argue that irregular warfare strategies and tactics played a significantly larger role in the outcome of events than previously acknowledged. This study illustrates the importance of guerrilla warfare and the strategy of elastic offence to Māori strategy. In contrast, it highlights the evolution of British military thinking from conventional conservatism to a multi-echelon force led by irregular warfare units and tactics. ‘Ungentlemanly Warfare’ argues that irregular warfare was central to military conflicts in nineteenth-century New Zealand.

text: Ungentlemanly warfare: The impact of irregular warfare on military strategy in the New Zealand Wars ‘Ungentlemanly Warfare’ examines the impact of irregular warfare on strategic thinking in the New Zealand Wars (1845–1872). Britain entered the period as an eighteenth-century force reliant on European methods of war. In contrast, Māori were an experienced bushfighting force depleted on manpower but experiencing a period of military innovation. This interaction led to an important exchange of strategic ideology and methods.  
This thesis tracks how Māori, British, and colonial forces developed and exchanged irregular warfare practices across three regions and time periods. The Northern War exposed the shortcomings of conventional military conduct. Māori leadership altered their strategic approach and pursued a strategy of elastic offence. In contrast, British leadership persisted with their ineffective conventional means of warfare. In the Waikato War, British strategy was influenced by the success of colonial irregulars. British strategic and operational methods changed with the inclusion of multi-echelon warfare and the indirect approach. Kīngitanga leadership improved their combat capacity through guerrilla warfare, decentralised command, and a grand strategy of elastic offence. The Taranaki and West Coast campaigns highlighted the relationship between the use of irregular warfare and military success in New Zealand. Both sides experienced success and failure across numerous conflicts, the defining factor being the active use of irregular warfare. These case studies reveal the significance of irregular warfare strategies and tactics to military success in colonial New Zealand. They also reveal opportunities and challenges to military adaptation in Māori, British, and colonial martial cultures of the nineteenth century. 
 ‘Ungentlemanly Warfare’ provides a unique approach to the examination of the New Zealand Wars conflict. It is an operational history that draws upon methods and aspects of the ‘war and society’ approach to military history, especially the use of Māori scholarship, evidence, and theory. The thesis’ chapters consider strategic and tactical decision-making across the numerous conflicts within the period. To do so, I provide close readings of primary evidence, including military communication and reports, early histories, and first-person accounts, to identify the roles of irregular warfare and strategic adaptions in the New Zealand Wars. 
	‘Ungentlemanly Warfare’ analyses the impact of irregular warfare on the strategic thinking of military leaders within the New Zealand Wars. I argue that irregular warfare strategies and tactics played a significantly larger role in the outcome of events than previously acknowledged. This study illustrates the importance of guerrilla warfare and the strategy of elastic offence to Māori strategy. In contrast, it highlights the evolution of British military thinking from conventional conservatism to a multi-echelon force led by irregular warfare units and tactics. ‘Ungentlemanly Warfare’ argues that irregular warfare was central to military conflicts in nineteenth-century New Zealand.

year: 2023