title: The physical and biological function of wood in New Zealand's forested stream ecosystems

authors: Baillie, Brenda Robin

subjects: wood

abstract: Since the arrival of humans approximately 1000 years before present (B. P.), New Zealand has lost approximately 80% of its forest cover and along with it, the contribution of wood to our aquatic ecosystems. The aim of this thesis was to undertake a large catchment-scale assessment of LW loadings, spatial distribution and morphological influence in an old-growth indigenous forest to provide some understanding on the natural characteristics of wood that would have been present in many river systems of New Zealand prior to human settlement. The second component of the thesis involved the experimental removal of wood from three small streams in order to provide some insight into what that loss of wood may have meant for fish and aquatic invertebrate communities. In the first part of the study, a catchment scale survey of large wood (LW) was completed in a 5thorder, old-growth forest river system. LW volumes ranged from 59-503 m³ ha⁻¹ and declined down the river system along with the number of LW pieces suspended across the channel and LW influence on channel morphology, whereas piece frequency, number of pieces in debris dams and length increased. Nearly half the pieces were influencing channel morphology, particularly wood accumulation, sediment storage, bank armouring, and pool formation. These key pieces were larger, longer and more stable than average. LW contribution to habitat complexity was highest in the middle to upper sections of the river system. Four key zones of wood distribution and influence were identified in the river system. Zonal boundaries were influenced by changes in transport capacity, fluvial processes and channel morphology. In the second part of the study, a field trial was established in three small forested streams to measure the influence of wood and its experimental removal on channel morphology, and indigenous fish and aquatic invertebrate communities. Prior to wood removal there were no significant differences in the total density of fish between wood pools (pools with wood cover), open pools and riffles. Total fish biomass was marginally significant with most of the fish biomass located in wood pools. At the species level, the density and biomass of banded kokopu (Galaxias fasciatus) and the weights of longfin eels (Anguilla dieffenbachii) were significantly higher in wood pools. Species richness, density and biomass of bluegill bullies (Gobiomorphus hubbsi), torrentfish (Cheimarrichthys fosteri) and the density of redfin bullies (Gobiomorphus huttoni) was highest in riffles. Differences in fish community composition were greatest between riffles and pools, whereas there was considerable overlap between the two pool types. Total invertebrate density was 70% higher in debris dams than riffles prior to wood removal, but this difference was not significant. Densities of Trichoptera (caddisfly) and Plecoptera (stonefly), and five aquatic invertebrate taxa were significantly higher in debris dams which also contained greater numbers of less common taxa (< 1% total catch) than riffles. Only Deleatidium sp. (Ephemeroptera) densities were significantly higher in riffles than in debris dams. Aquatic invertebrate communities in debris dams differed significantly from those in riffles and season had a significant influence on aquatic invertebrate community structure. Removal of wood and associated debris dams from the treatment sections in each of the three streams resulted in a simplified channel morphology, significantly increasing the length and area in riffles and reducing the area of pools. The impact on the fish community was greatest for the two larger fish, banded kokopu and large longfin eels, whose abundance declined in the treatment sections. At the reach scale, only banded kokopu biomass showed a significant decline following wood removal. Invertebrates were less affected by wood removal and associated loss of debris dams. Invertebrate composition in the remaining riffles in the treatment sections had a higher proportion of Ephemeroptera and lower proportions of Trichoptera, Plecoptera and Diptera with fewer rare species than remaining debris dams in the control sections, but there were no discernable effects on invertebrate densities and functional feeding groups at the reach scale. Public perception of wood in waterways is mainly negative and wood is managed primarily to reduce flood damage in New Zealand’s streams. With continued research and advocacy on the environmental benefits, careful planning and judicial use, there is the potential to make better use of wood to rehabilitate and enhance New Zealand’s stream environments. This thesis provides some insight into the contribution of wood to forested stream ecosystems in New Zealand and the implicit losses associated with forest removal. It also contributes to our global understanding on the role of wood, its contribution to habitat heterogeneity and influence on biological communities.

text: The physical and biological function of wood in New Zealand's forested stream ecosystems Since the arrival of humans approximately 1000 years before present (B. P.), New Zealand has lost approximately 80% of its forest cover and along with it, the contribution of wood to our aquatic ecosystems. The aim of this thesis was to undertake a large catchment-scale assessment of LW loadings, spatial distribution and morphological influence in an old-growth indigenous forest to provide some understanding on the natural characteristics of wood that would have been present in many river systems of New Zealand prior to human settlement. The second component of the thesis involved the experimental removal of wood from three small streams in order to provide some insight into what that loss of wood may have meant for fish and aquatic invertebrate communities. In the first part of the study, a catchment scale survey of large wood (LW) was completed in a 5thorder, old-growth forest river system. LW volumes ranged from 59-503 m³ ha⁻¹ and declined down the river system along with the number of LW pieces suspended across the channel and LW influence on channel morphology, whereas piece frequency, number of pieces in debris dams and length increased. Nearly half the pieces were influencing channel morphology, particularly wood accumulation, sediment storage, bank armouring, and pool formation. These key pieces were larger, longer and more stable than average. LW contribution to habitat complexity was highest in the middle to upper sections of the river system. Four key zones of wood distribution and influence were identified in the river system. Zonal boundaries were influenced by changes in transport capacity, fluvial processes and channel morphology. In the second part of the study, a field trial was established in three small forested streams to measure the influence of wood and its experimental removal on channel morphology, and indigenous fish and aquatic invertebrate communities. Prior to wood removal there were no significant differences in the total density of fish between wood pools (pools with wood cover), open pools and riffles. Total fish biomass was marginally significant with most of the fish biomass located in wood pools. At the species level, the density and biomass of banded kokopu (Galaxias fasciatus) and the weights of longfin eels (Anguilla dieffenbachii) were significantly higher in wood pools. Species richness, density and biomass of bluegill bullies (Gobiomorphus hubbsi), torrentfish (Cheimarrichthys fosteri) and the density of redfin bullies (Gobiomorphus huttoni) was highest in riffles. Differences in fish community composition were greatest between riffles and pools, whereas there was considerable overlap between the two pool types. Total invertebrate density was 70% higher in debris dams than riffles prior to wood removal, but this difference was not significant. Densities of Trichoptera (caddisfly) and Plecoptera (stonefly), and five aquatic invertebrate taxa were significantly higher in debris dams which also contained greater numbers of less common taxa (< 1% total catch) than riffles. Only Deleatidium sp. (Ephemeroptera) densities were significantly higher in riffles than in debris dams. Aquatic invertebrate communities in debris dams differed significantly from those in riffles and season had a significant influence on aquatic invertebrate community structure. Removal of wood and associated debris dams from the treatment sections in each of the three streams resulted in a simplified channel morphology, significantly increasing the length and area in riffles and reducing the area of pools. The impact on the fish community was greatest for the two larger fish, banded kokopu and large longfin eels, whose abundance declined in the treatment sections. At the reach scale, only banded kokopu biomass showed a significant decline following wood removal. Invertebrates were less affected by wood removal and associated loss of debris dams. Invertebrate composition in the remaining riffles in the treatment sections had a higher proportion of Ephemeroptera and lower proportions of Trichoptera, Plecoptera and Diptera with fewer rare species than remaining debris dams in the control sections, but there were no discernable effects on invertebrate densities and functional feeding groups at the reach scale. Public perception of wood in waterways is mainly negative and wood is managed primarily to reduce flood damage in New Zealand’s streams. With continued research and advocacy on the environmental benefits, careful planning and judicial use, there is the potential to make better use of wood to rehabilitate and enhance New Zealand’s stream environments. This thesis provides some insight into the contribution of wood to forested stream ecosystems in New Zealand and the implicit losses associated with forest removal. It also contributes to our global understanding on the role of wood, its contribution to habitat heterogeneity and influence on biological communities.

year: 2011

title: Thermotolerant purple nonsulfur bacteria from New Zealand geothermal areas

authors: Charlton, Peter John

abstract: Purple nonsulfur bacteria (PNSB) are a metabolically and nutritionally diverse group of photosynthetic organisms that have been isolated from many environments. Three thermotolerant or mildly thermophilic strains are known from thermal areas in the United States and Japan. Only mesophilic isolates have been obtained from Russian hot springs. 

Enrichment cultures selective for PNSB were set up on samples taken from a range of New Zealand geothermal areas. Photosynthetic purple bacteria could readily be isolated from Waimangu and Orakei Korako samples, but could not be isolated from Tokaanu mats. In total, 35 isolates belonging to the genera Rhodopseudomonas, Rhodoplanes, Blastochloris, Rubrivivax, Rhodomicrobium, Rhodospirillum and Phaeospirillum were obtained from 18 positive sample sites. The majority of isolates grew optimally around 40°C and had temperature maxima ranging from 43 to 47°C. Other isolates had lower optima and were thermotolerant. Many Rhodoplanes and Blastochloris isolates represented novel genospecies, though some could not be unambiguously distinguished by their phenotypic properties. The novel species Rhodoplanes venustus sp. nov., Rhodoplanes segnis sp. nov., and Phaeospirillum tepidarium sp. nov. are proposed. 

Molecular methods were used to specifically detect photosynthetic purple bacteria. A clone library of photosynthetic reaction centre pufL genes amplified from an Orakei Korako mat sample was constructed and screened. No clone sequences were identical to those of organisms isolated previously or in the current study. The clone library was dominated by sequences attributable to aerobic anoxygenic phototrophic bacteria. Four novel pufL sequences attributable to purple nonsulfur bacteria were obtained.

Rhodoplanes strains possessed the ability to use nicotinic acid as sole source of carbon and nitrogen, via a pathway that includes 6-hydroxynicotinate and glutarate as intermediates, as are in the Azorhizobium caulinodans pathway. Unlike other nicotinic-acid degrading organisms, growth of Rhodoplanes on nicotinate was not inhibited by addition of tungstate.

text: Thermotolerant purple nonsulfur bacteria from New Zealand geothermal areas Purple nonsulfur bacteria (PNSB) are a metabolically and nutritionally diverse group of photosynthetic organisms that have been isolated from many environments. Three thermotolerant or mildly thermophilic strains are known from thermal areas in the United States and Japan. Only mesophilic isolates have been obtained from Russian hot springs. 

Enrichment cultures selective for PNSB were set up on samples taken from a range of New Zealand geothermal areas. Photosynthetic purple bacteria could readily be isolated from Waimangu and Orakei Korako samples, but could not be isolated from Tokaanu mats. In total, 35 isolates belonging to the genera Rhodopseudomonas, Rhodoplanes, Blastochloris, Rubrivivax, Rhodomicrobium, Rhodospirillum and Phaeospirillum were obtained from 18 positive sample sites. The majority of isolates grew optimally around 40°C and had temperature maxima ranging from 43 to 47°C. Other isolates had lower optima and were thermotolerant. Many Rhodoplanes and Blastochloris isolates represented novel genospecies, though some could not be unambiguously distinguished by their phenotypic properties. The novel species Rhodoplanes venustus sp. nov., Rhodoplanes segnis sp. nov., and Phaeospirillum tepidarium sp. nov. are proposed. 

Molecular methods were used to specifically detect photosynthetic purple bacteria. A clone library of photosynthetic reaction centre pufL genes amplified from an Orakei Korako mat sample was constructed and screened. No clone sequences were identical to those of organisms isolated previously or in the current study. The clone library was dominated by sequences attributable to aerobic anoxygenic phototrophic bacteria. Four novel pufL sequences attributable to purple nonsulfur bacteria were obtained.

Rhodoplanes strains possessed the ability to use nicotinic acid as sole source of carbon and nitrogen, via a pathway that includes 6-hydroxynicotinate and glutarate as intermediates, as are in the Azorhizobium caulinodans pathway. Unlike other nicotinic-acid degrading organisms, growth of Rhodoplanes on nicotinate was not inhibited by addition of tungstate.

year: 2002

title: How Maui captured the sun: using a MUD for educational simulation

authors: Cunningham, Sally Jo

subjects: computer science

abstract: MUDs (Multi-User Dungeons) are text-based, multi-user communication and modelling programs. This paper investigates the potential of a popular extensible MUD, the LambdaMOO system, as a tool for second language training and for educational simulation gaming.

text: How Maui captured the sun: using a MUD for educational simulation MUDs (Multi-User Dungeons) are text-based, multi-user communication and modelling programs. This paper investigates the potential of a popular extensible MUD, the LambdaMOO system, as a tool for second language training and for educational simulation gaming.

year: 1995-12