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    Seasonal and year to year variation in the macroinvertebrate communities of New Zealand forest streams : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Science in Ecology at Massey University, Palmerston North, New Zealand
    (Massey University, 2002) Minchin, Stephen Mark
    The bed movement of 42 streams in the Ruahine Forest Park, Urewera National Park, and Cass-Craigiebum region was predicted from each stream's channel and catchment characteristics. While a stepwise regression was relatively unsuccessful in predicting tracer particle movement, an artificial neural network analysis achieved strong correlations with measured tracer particle data. Forty-three streams in the Ruahine and Tararua Forest Parks were sampled in the summers of 1996 and 2001, and the macroinvertebrate communities compared. Changes in community structure between the two surveys did not correlate with any measured environmental characteristics including stream bed movement and change in periphyton biomass. MCI scores changed by a mean of 12.8 points between the two surveys, and the number of sites attaining an MCI score indicative of a 'pristine' stream dropped from 40 to 29. This appears to be related to a change in stream temperature, with streams that were cooler in 2001 than in 1996 showing an increase in MCI, while those which were warmer showed a decrease. Changes such as these could have a marked effect on biomonitoring programmes that use reference sites similar to these streams. In both 1996 and 2001, a greater number of taxa were collected from sites with more periphyton - taxon richness appears to asymptote at chlorophyll a concentrations greater than 5 μg/cm² Twelve streams within the Ruahine Forest Park were sampled every three months between June 2000 and May 2001. Both periphyton biomass and macroinvertebrate taxon richness tended to decrease with bed movement. While macroinvertebrate community structure showed marked changes over the study period, these changes were not linked to bed movement or variation in periphyton level. The seasonal changes observed in these streams are not significantly different to the changes seen between the summers of 1996 and 2001 - community structure was no more stable between two summers separated by five years than it was between the seasons of a single year. Eight artificial channels were laid on the bed of the Turitea Stream. At the onset of the experiment, half of the channels contained neither invertebrates nor periphyton cover, while the other half had no invertebrates but an initial periphyton layer. Drift samples indicate that approximately one in four drifting invertebrates colonised the channels during the 14 day study period, with benthic taxon richness reaching a peak after only four days. Colonisation was not affected by periphyton biomass. Some of the less common taxa that were present in the water column did not colonise the channels within 14 days.
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    The middle Pleistocene extinction of bathyal benthic foraminifera in the South Atlantic (ODP sites 1082 and 1088) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Earth Science at Massey University
    (Massey University, 2005) O'Neill, Tanya Ann
    The youngest major turnover in deep-sea benthic foraminifera (termed the Stilostomella extinction) is documented in two ODP sites in the South Atlantic Ocean. This study is the first detailed investigation of its kind in this region, and reveals the pulsed decline and eventual extinction of 33 species of elongate, cylindrical benthic foraminifera belonging to the families Stilostomellidae, Pleurostomellidae, and part of the Nodosariidae during the mid-Pleistocene climatic transition (MPT, ~1200 - 600ka). Furthermore, the Stilostomella extinction is limited to elongate species with highly specific apertural characteristics (e.g. cribrate, slit lunate, and hooded with secondary teeth), such as Chrysalogonium, Ellipsoglandulina, and Pleurostomella species, respectively. Micropaleontological and sedimentological data from lower bathyal Sites 1082 and 1088 (1290 m and 2082 m water depth, respectively) provide a proxy record of oceanographic changes in the South Atlantic Ocean through the MPT. This study compares the timing and causes of the Stilostomella extinction between two highly contrasting environmental settings in relation to paleoceanographic history, sediment regime and paleoproductivity. In the South Atlantic, the abundance and accumulation rate of Extinction Group (EG) taxa began to decline between ~ 1070 and 1000 ka at both core sites. The rate of decline was pulsed, with major declines usually associated with cool periods, and partial recoveries during intervening warm periods. The timing of highest occurrences (HOs) was diachronous between sites, and the final Stilostomella extinction datum is marked by the uppermost occurrence of Myllostomella matanzana and Siphonodosaria sagrinensis at ~705 ka in Site 1082, and Myllostomella matanzana and Pleurostomella alternans at ~600 ka in Site 1088. This corresponds with the previously documented global Stilostomella extinction datum within the period of 700 and 570 ka. Detailed comparisons with North Atlantic and Southwest Pacific studies confirm the highly diachronous nature of HOs of EG species, and furthermore, reveal that there is a lead time of ~100 kyr between HOs of the same species in the North Atlantic, compared with the South Atlantic. This study suggests that declines and extinctions at Site 1082 were primarily driven by highly fluctuating food supply associated with increased productivity caused by intensified upwelling during MPT glacial periods. In contrast, extinctions at Site 1088 appear to have been a result of the MPT reorganisation of the global deep-water 'conveyor belt', with δ 13 C gradients revealing that high dissolved oxygen Glacial North Atlantic Intermediate Water (GNAIW) bathed the region during cool periods. Far from a simple response to change in a single parameter, numerous factors have interacted and appear to have caused the demise of the Stilostomella extinction taxa. These factors include encroachment by well-ventilated (high dissolved oxygen) GNAIW, fluctuations in food supply, and possibly winnowing (of the phytodetritus layer) by vigorous bottom currents during MPT glacial periods.
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    The influence of hydrology and landscape on stream invertebrate communities of the Whanganui Catchment, New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Master of Philosophy in Ecology at Massey University
    (Massey University, 2002) Lemke, Dawn
    This study examines the effect of the hydrological regime and landscape characteristics on benthic stream macroinvertebrate communities in the Whanganui Catchment, New Zealand, using a variety of statistical techniques. A total of 36 hydrological variables were considered. Thirteen of these were calculated from long-term flow and rainfall records, and interpolated using geographic information systems (GIS) to cover the area of interest. Ten hydrological variables were derived from topographical maps though GIS, with a further 13 hydrological variables determined from rainfall information relating to the timing since the last event. Catchment and riparian landscape variables (land cover, geology and soil type) were derived from New Zealand's land classification database and land resource inventory using GIS. Community structure was measured using an ordination, species richness, total number of animals and the densities of 22 common taxa. Biological data was also quantified with a variety of diversity and water quality indices including Simpson's, Margalef's and Macroinvertebrate Community Index. Individual links between biological and all environmental data were explored through Pearson's correlations. Multiple regression was used to examine the combination of the environmental variables that were best in determining individual characteristics of community structure. Canonical correlation was utilized to assess overall concurrent patterns between landscape and biotic data. Stepwise logistic regression and classification trees were used to explore occurrence of the 22 selected taxa in relation to environmental variables. Of the modelling techniques assessed for prediction of taxa occurrence classification trees gave as good or better predictions than the other models and tended to produce simpler models, suggesting that it is probably a better modelling technique for this data. Of the environmental variables, FRE3 (number of flood events per year over 3 times the medium flow) was the best individual predictor of community structure, showing the greatest number of links and strongest relationships with the biotic variables. The other hydrological variables of river size and specific discharge also had numerous individual correlations, and as they are easier to calculate they may be more appropriate for use in ecological studies. Time since the last event was another important component in determining invertebrate community structure. Hydrological characteristics dominated the explanatory variables in many of the models representing water quality and diversity indices, suggesting that indices that measure water quality and diversity may only be comparable over areas with similar hydrological regimes. Landscape variables, as measured by this study, were also shown to influence invertebrate community structure but to a lesser extent than hydrology. All indices and ordinations show significant multiple regressions with landscape variables with 12 out of the 22 taxa models being highly significant. Canonical correlations of landscape variables showed catchment scale variables to be more predictive of community structure than riparian scale variables. When separating landscape variables into land cover and geology no clear pattern of dominance was shown.
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    Methods of assessment of macroinvertebrate biodiversity in New Zealand streams : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Ecology at Massey University
    (Massey University, 2002) Murray, Angela Louise
    In this study different sampling methodology and strategy was explored to develop an efficient inventory protocol for assessing biodiversity of stream macroinvertebrates in New Zealand. In a preliminary study 3 benthic invertebrate sampling techniques (Surber, kicknet and individual stone sampling) were compared to examine which maximised collected biodiversity per unit effort. Kicknet samples collected a higher number of taxa than either Surber or individual stone samples. Three-minute kicknets collected significantly more taxa than the other techniques, although 30-second kicknets collected the most taxa per unit effort. Detrended correspondence analysis of sampling techniques showed groupings of 30-second and 1-minute kicknets, 5 or more Surber samples, or individual stones samples collected the best representation of the community. Three strategies of sample collection using kicknet samples were investigated in 54 streams, in 3 conservation regions in the South Island, to see which collected greater taxa richness per unit effort. These strategies examined taxa accumulation in three samples in a) the same stream, b) different streams within one region, c) different streams in each of the 3 regions. Collected taxa richness was higher when sampling effort was spread over more habitats and a larger area i.e., strategy b and c. Environmental characteristics measured at each stream, were assessed to examine links between community structure and habitat characteristics. Community structure was most strongly linked with altitude, canopy cover, moss cover, stream width, and temperature. Five groups of communities were identified ranging from small high altitude streams with moss and high canopy cover, to larger more open low altitude streams. These groups had a common core of invertebrate taxa that differed in density and relative abundance. To test for the presence of indicator taxa of biodiversity, individual taxa densities were correlated with total taxa richness. Several taxa e.g., Archichauliodes diversus and Coloburiscus humeralis showed positive linkages with taxa richness, but none were particularly strong suggesting indicator taxa might not be appropriate for the measurement of invertebrate biodiversity in New Zealand streams.
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    Linkages between hyporheic and benthic invertebrate communities in New Zealand gravel bed rivers : a thesis presented in fulfilment of the requirements for the degree of Doctor of Philosophy in Ecology at Massey University
    (Massey University, 2000) Fowler, Reece Trevor
    Surber samples from the benthos and T-bar samples (14 mm PVC pipe diameter) from the hyporheos were collected from 8 Southern Hawkes Bay rivers, differing in environmental conditions and geological age, and 8 rivers of the Cass/Craigieburn region of Canterbury that had differing physical stability and hyporheic physicochemical characteristics. Gravel bedded rivers of the Southern Hawkes Bay (North Island) and Cass/Craigieburn region (South Island) were sampled to examine the spatial distribution of the hyporheos in relation to physicochemical factors, bed stability and the significance of the hyporheic zone as a refuge and/or source of invertebrate colonists to the benthos. Physical bed movement, the duration of channel dewatering and flow variance were used to measure disturbance to the hyporheos and benthos, respectively. Benthic invertebrate communities of many streams are subject to constant disturbance from fluctuations in flow, temperature, and bed movement. In contrast, the hyporheos residing in the hyporheic zone may not experience the same disturbance regimes because bed movement occurs less often in the hyporheic zone and there is less diel temperature, dissolved oxygen and flow fluctuations. In the rivers investigated, broad (between river) and finer (within river) scale environmental factors influenced the composition of the hyporheos. Local geomorphology appeared to have a significant effect on the hyporheos by markedly increasing the proportion of epigean animals (benthic animals resident in the hyporheos) at sites of young geomorphology (less that 0.05 mya). In contrast, hypogean animals (animals seldom encountered from the benthos) dominated geologically older sites (greater than 0.4 mya). Species diversity in the hyporheic zone was highest with intermediate levels of bed movement where both hypogean and epigean animals were present. The greater abundance of epigean fauna with increasing bed movement may reflect differences in disturbance regime between sites and in turn interstitial flow rates. However, it is unlikely that the geological age and stability of bed substrates determined community composition alone. Water chemistry was also an important factor determining community composition; epigean animals were more abundant in the hyporheic zone when hyporheic water chemistry was similar to the surface river water (e.g., higher dissolved oxygen and lower conductivity). In contrast, hypogean animals dominated the hyporheos when water chemistry was least like the surface water (e.g., lower dissolved oxygen and higher conductivity). Dewatering and bed movement may disturb the hyporheos by desiccating or physically disturbing the hyporheic zone, respectively. If the potential colonists of the hyporheic zone are removed by desiccation or physical abrasion, the types of invertebrate taxa colonising will change because some invertebrates may be less capable of colonising from this region. The proportion of epigean animals may increase in the hyporheic zone with greater bed movement, but decline during stable conditions or at stable sites because the interstitial environment becomes less like the surface. Thus, the hyporheic zone may harbour benthic invertebrates during disturbance events and may be an important source of colonists for the benthos in frequently disturbed sites. In contrast, during stable conditions, or at stable sites, factors other than disturbance (e.g., substrate compactness, organic matter supply, competition or surface/groundwater interactions) may be more important in determining community composition. The diverse hyporheos identified in New Zealand rivers may be influenced by substrate composition, which may in turn alter interstitial flow patterns, discharge variance and the probability of bed movement.