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    The impact of stormwater discharges on freshwater, marine water and marine sediments and the implications for environmental management of the Pauatahanui Inlet, Porirua, New Zealand: A thesis prepared in partial fulfilment of Masters of Applied Science (Natural Resource Management), Massey University.
    (Massey University, 2002) Hooper, Kathryn L
    A survey of Cu, Pb, Zn and Cr levels in sediment cores taken at four locations in the Pauatahanui Inlet has been undertaken in conjunction with a freshwater and marine water quality survey. Levels of heavy metals in sediment were within the Australian and New Zealand Guidelines for Fresh and Marine Water Quality for the protection of Aquatic Ecosystems, [Interim Sediment Quality Guideline (ISQG) (high level of protection)]. Sediments in the vicinity of discharges from suburban catchments showed higher levels of Cu, Pb, Zn and Cr than those in the vicinity of rural catchments. Levels of Cu, Pb and Zn in streams in the suburban catchments exceeded guideline levels for 99% species protection on occasions, and guidelines for Cu, Pb and Cd were exceeded in marine water. Elevated concentrations of heavy metals in marine and freshwater coincided with rainfall events and increased suspended sediment levels, indicating stormwater discharges as a contributing source of the contaminants. Levels of N and P exceeded guideline trigger values in freshwater tributaries on occasions. There was no distinct difference between the rural and suburban catchments in terms of nutrient levels detected. Levels of bacteria present (E-Coli and Enterococci) exceeded NZ guideline levels for contact recreation purposes after rainfall events. Heavy metals in stormwater were attributed to transport sources. Control of these discharges will likely be ‘end of pipe’ in nature due to the diffuse nature of the heavy metal inputs, and the difficulties in controlling emissions from vehicles at source.
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    Freshwater fish community structure in Taranaki : dams, diadromy or habitat quality? : a thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Ecology at Massey University
    (Massey University, 1999) Joy, Michael Kevin
    The relationships between freshwater fish community structure and habitat characteristics including dams were examined at 85 sites on 38 waterways draining Mount Taranaki during the summer of 1997/98. Thirteen native and two exotic fish species were captured. Four groupings were identified based on species composition. The first two were high elevation site groups: one dominated by the diadromous Galaxiids: shortjawed kokopu, banded kokopu and koaro, the other dominated by longfin eels. The third group of sites was a mid-elevation group dominated by redfin bullies and longfin eels while the fourth group was made up of low elevation sites dominated by redfin bullies and shortfin eels. Discriminant analysis revealed that distance from the sea, site elevation and the presence of dams were the environmental variables most strongly associated with fish distribution patterns. Data from the New Zealand freshwater fish database (NZFFD) were used to examine the influence of dams and other environmental variables on the fish communities. The sites listed in the NZFFD as having free migratory access were used as reference sites for the construction of a predictive model of fish community assemblage. The species found at test sites were compared with the predicted assemblage and an observed over predicted ratio (O/P) produced for each test site in order to evaluate the relative impact of migratory barriers. The 85 sites from the 1997/98 survey, which were independent of the reference sites used in the model, were used as a test of the model. The O/P ratios were significantly lower for sites above barriers when compared with sites with free access. To demonstrate the use of the model, the impact of the Motukawa dam on fish communities was analysed by comparing the O/P ratios for sites above and below the dam. The resulting ratios were significantly lower above the dam, indicating that the dam was having a negative impact on fish communities. Distinctive trajectories of occurrence were detected for 13 species from the Taranaki ring plain. The diadromous species were ranked based on their ability to penetrate inland to enable comparison with other regions. The Taranaki rankings were consistent with rankings for the same species from the West Coast of the South Island. The high proportion of diadromous species in the Taranaki fauna means that access is of primary importance in structuring the fish communities and the large number of dams in the region has had a discernable negative effect on freshwater fish communities.
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    The development of the Waterway self assessment form, a stream management tool for landowners : a thesis presented in partial fulfilment of the requirements for the degree of Masters of Science in Ecology at Massey University
    (Massey University, 2000) Polglase, Miranda Anne
    Increasing environmental awareness amongst the general public and more specific user groups, such as land owners, has led to concern about the impacts of land use on specific environmental qualities such as water quality and stream biota. As a result, methods for reducing and or ameliorating these impacts have become a key area of research in freshwater ecology over the last decade (Fahey and Rowe, 1992; Hanchet, 1989; Hughes, et al., 1986; Osborne and Wiley, 1988; Quinn, et al., 1997; Watson, 1986; Wilcock, 1986; Winterbourn, 1986). The dominant focus of this research has been in riparian management (Large and Petts, 1992; Platts, et al., 1987; Quinn, et al., 1993). As many streams and rivers in New Zealand flow at some stage through pastoral land, the responsibility of managing riparian zones is largely that of the landowners. Simple tools for managing waterways and their riparian zones, which take into account the requirements of individual landowners, and also facilitate education and awareness, are now needed (Quinn and Collier, in press).
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    The effects of productivity and disturbance on diversity in stream communities : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Ecology at Massey University, Palmerston North, New Zealand
    (Massey University, 2010) Tonkin, Jonathan Douglas
    The application of conventional diversity models in streams has had limited success as stream communities often fit outside the model assumptions. Of the plethora of influences on stream macroinvertebrate diversity, productivity and disturbance dominate. Yet there remains to be a consensus on the form of these relationships and whether productivity and disturbance interact to predict diversity. Therefore, the aim of this thesis was to the assess linkages between productivity, disturbance and diversity in stream macroinvertebrate communities and further the understanding of these links. I achieved this through multiple assessments throughout New Zealand (NZ) and Spain between February 2007 and December 2009. I (i) assessed multivariate models of productivity‐disturbance‐diversity within NZ streams and examined whether canopy presence modulated these links and (ii) whether land‐use affected these relationships. I further assessed (iii) the productivity‐diversity relationship in Spanish streams and whether this was underpinned by specific periphyton‐invertebrate associations and (iv) if the relationship matched those of NZ and formed a global trend. Finally, I experimentally examined (v) the influence of spatial scale on productivity‐ and disturbance‐diversity relationships. The prevailing premise throughout the thesis is that diversity increased with increasing productivity and declined with increasing disturbance, although the form of these links varied. There was no evidence of a productivity‐disturbance interaction throughout this thesis and these relationships were not affected by land‐use but were by canopy presence. Where relationships with productivity lacked, I demonstrate this link may be underpinned by interactions between invertebrates and specific forms of algae, as well as simply being a function of the range of productivity assessed or even the spatial scale of assessment. In fact, productivity setting the upper limit to richness may be a universal pattern in streams with no evidence of productivity leading to greater competitive interactions despite the wide ranges assessed. Overall, this thesis makes significant progress in clarifying these relationships in streams. I provide further evidence suggesting the DEM does not apply in stream communities and clearly demonstrate additive, rather than interactive, effects of productivity and disturbance.
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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.
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    Fine scale spatial behaviour of indigenous riverine fish in a small New Zealand stream : a thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Conservation Biology at Massey University, Palmerston North
    (Massey University, 2009) McEwan, Amber Julie
    The substrate and flow characteristics of a 100m reach of a small, North Island, New Zealand stream were mapped and drawn to a 0.25m2 grid scale. One hundred and thirty four individual fish, representing five native and one introduced species were PIT tagged and then monitored with a portable transceiver over 41 occasions during day and night in autumn to winter of 2008, then on 3 occasions in January 2009. Redfin bullies (Gobiomorphus huttoni), shortjaw kokopu (Galaxias postvectis) and koaro (Galaxias brevipinnis) were most commonly represented and redetected in the 100m reach (75%, 73%, and 83% detection rates respectively). Redfin bullies with a lower condition factor than conspecifics were less likely to be redetected and gravid fish were considered more at risk of infection or death associated with PIT tagging. Shortjaw kokopu were less likely to be redetected but more likely to retain tags in the longer term than both redfin bullies and koaro. No difference was found in tag detection rates at a range of flow levels, nor between day and night surveying, although a small decline in detection rates occurred as water temperature decreased. Four hundred and twelve locations of untagged fish were collected during 14 night samples and added to the dataset of 557 locations of PIT tagged fish. A total of 1112 (82% of the reach) 0.25m2 grid squares were inventoried for microhabitat characteristics using 16 physical variables which, together with fish locations, enabled the microhabitat characteristics of the grid squares where fish were found to be compared with those where fish were not found. Redfin bullies and shortjaw kokopu showed strong associations with large substrates and large interstitial refuge spaces and both species showed marked diel differences in microhabitat utilisation. Koaro were more dependent on velocity and surface turbulence and used similar microhabitat types regardless of diel period. No size-based or seasonal differences were found regarding microhabitat use. Potential segregation was observed between shortjaw kokopu and koaro but no other biotic influences on habitat utilisation were apparent. Three floods occurred during the 2008 sampling period which facilitated the collection of fish behavioural data in relation to high flows. A total of 31 individuals were detected during flood conditions and these were found either within 0.5 metres of the base flow stream bed edge or inside the base flow stream bed in areas with large boulder substrates. A subset of the population was found returning to the same locations during multiple floods. Individual fish detected during high flows were significantly less familiar (see pages 68-69 for a detailed description of the term “familiar” in this context) in comparison to the subset of individuals that were commonly resident in the study reach during base flow conditions, showing that tagged fish made larger scale movements during flood conditions. While small changes in community composition occurred that were able to be attributed to flood-induced microhabitat changes, overall a remarkable level of persistence was observed in the tagged community, with over half of all individuals remaining in or returning to the same 100m section of stream following each flood.
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    The development of predictive models to enhance biological assessment of riverine systems in New Zealand : a thesis presented in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Ecology at Massey University, Palmerston North, New Zealand
    (Massey University, 2003) Joy, Michael Kevin
    A suite of new regional and national lotic freshwater bioassessment tools were developed for New Zealand. This work permits the inclusion of freshwater fish in bioassessment, a component of the fauna previously largely ignored. The multivariate predictive models developed gave a number of advantages over the existing albeit overextended single-index approach (the macroinvertebrate community index) used by regional authorities. To acquire the data for constructing the models more than 500 sites were sampled over three North Island regions. The sites were selected to represent least impacted conditions known as reference sites so that the biotic communities sampled would representing the best attainable or the goal for resource managers. Models were constructed to predict the biota representing best available conditions based on the non human influenced physicochemical variables defining the sites. The predicted and observed assemblages were then compared using an observed over expected ratio (O/E) so that scores less than 1 represent less [i.e. fewer] species observed than expected. This (O/E) ratio is more than simply the assessment of species richness, as only those species predicted are included in the ratio. Reference site multivariate predictive models using fish and macroinvertebrate assemblage groups were developed for bioassessment in the Manawatu-Wanganui Region. Two reference site multivariate predictive models using individual fish and decapod species were developed for the Auckland region. The first used traditional linear discriminant function analysis and the second used artificial neural networks (ANNs). A model to predict the spatial occurrence of fish and decapods was developed for fish in the Wellington Region using Geographic Information Systems (GIS) and ANNs. The remotely sensed data was available for all rivers in the region so the predictions could be extended over the entire stream network to produce a fish map. Finally an index of biotic integrity (IBI) using fish was developed for the entire country and evaluated using remotely assessed environmental data. Exhaustive evaluations of predictions from all the models confirmed their credibility as a biomonitoring.