Michael K. Joy

New Zealand Dairy Farming: Milking Our Environment for All Its Worth

AbstractOver the past two decades there have been major increases in dairy production in New Zealand. This increase in intensity has required increased use of external inputs, in particular fertilizer, feed, and water. Intensified dairy farming thus incurs considerable environmental externalities: impacts that are not paid for directly by the dairy farmer. These externalities are left for the wider New Zealand populace to deal with, both economically and environmentally. This is counter-intuitive given the dairy industry itself relies on a ‘clean green’ image to maximize returns. This is the first nationwide assessment of some of the environmental costs of the recent increase of dairy intensification in New Zealand. Significant costs arise from nitrate contamination of drinking water, nutrient pollution to lakes, soil compaction, and greenhouse gas emissions. At the higher end, the estimated cost of some environmental externalities surpasses the 2012 dairy export revenue of NZ

Monitoring a New Zealand freshwater fish community using passive integrated transponder (PIT) technology; lessons learned and recommendations for future use

11.6xa0billion and almost reaches the combined export revenue and dairy’s contribution to Gross Domestic Product in 2010 of NZ

Linking disturbance and stream invertebrate communities: how best to measure bed stability

5xa0billion. For the dairy industry to accurately report on its profitability and maintain its sustainable marketing label, these external costs should be reported. This assessment is in fact extremely conservative as many impacts have not been valued, thus, the total negative external impact of intensified dairying is probably grossly underestimated.n

Habitat use of redfin bullies (Gobiomorphus huttoni) in a small upland stream in Manawatu, New Zealand

Abstract One hundred and thirty individual fish were collected and passive integrated transponder (PIT) tagged in a 100-m reach of a small North Island, New Zealand stream. The positions of the fish were monitored with a hand-held portable PIT antenna over 41 occasions during day and night in 2008/2009. Redfin bully (Gobiomorphus huttoni), shortjaw kokopu (Galaxias postvectis) and koaro (Galaxias brevipinnis) were the most represented and commonly detected species (75%, 73% and 83% detection rates, respectively). Nine longfin eels (Anguilla dieffenbachii) were tagged but only two were later detected. Redfin bullies with lower condition factors than conspecifics were less likely to be detected following tag implantation. Shortjaw kokopu were less likely to be detected but more retained tags than redfins and koaro. No difference in tag detection rates was found over a range of flow levels, nor between surveying during day and night, although a small decline in detection rates occurred as water temperature decreased and with time since sampling. The PIT technique proved to have significant potential for monitoring New Zealand native stream fish communities and has many advantages over previously used techniques, particularly in relation to the collection of fine-scale spatial data on multiple species.

A macroinvertebrate index to assess stream-bed stability

Abstract Substrate stability is a key determinant of stream invertebrate community composition, but its measurement can be problematic. Stream ecologists often use different approaches and techniques to quantify bed stability, and this variability makes comparison among studies difficult. We examined the link between 6 reach-scale measures of substrate stability and invertebrate community metrics in 12 New Zealand mountain streams. The strength of the link varied with the method used to define substrate stability. We used morphological budgeting to measure spatial patterns and volumes of scour and fill. We found that as erosion of sediments increased, invertebrate diversity declined exponentially. In particular, increases in the volume of scour reduced taxonomic richness, whereas deposition of coarse sediments was less relevant for invertebrate communities. Overall, the distance travelled by in-situ-marked tracer stones was most strongly linked with all invertebrate community metrics, whereas the bottom component of the Pfankuch Index related very well to diversity. Both metrics showed near-linear declines in diversity with decreasing stability. In contrast, the link between invertebrate communities and the proportion of bed area affected by entrainment was weak. Therefore, we propose tracer-based indices and the Pfankuch bottom component as the most suitable measures for research involving invertebrate–substrate-stability relationships. Measures derived from in-situ-marked tracer stones reflected only entrainment and transport of particles. In contrast, the bottom component of the Pfankuch Index encompassed the widest range of bed-stability characteristics but is prone to observer bias. An objective method that combines the efficiency of the Pfankuch Index with the characteristics measured using tracer stones could serve as a powerful explanatory tool in stream ecology.

Responses of three PIT-tagged native fish species to floods in a small, upland stream in New Zealand

This study uses Passive Integrated Transponder (PIT) technology to describe the habitat use patterns of the small, benthic redfin bully (Gobiomorphus huttoni). A 100-m reach of small upland stream in Manawatu, New Zealand was mapped to scale and inventoried for microhabitat variables. Flow velocity, depth, surface turbulence, substrate size and interstitial refuge space availability were measured in 0.25-m2 quadrats throughout the reach. A total of 67 redfin bullies were PIT tagged within the reach and monitored during day and night surveys in 2008 with a portable PIT monitoring system. Of these, 72xa0% were detected at least once and 64xa0% were detected 5 times or more within the study reach. Univariate analyses showed that redfin bullies utilized microhabitats that had larger substrate particles and more interstitial refuge spaces compared with all microhabitats available in the reach. During the day, redfin bullies were found in areas with larger substrates than areas where they were found at night. No differences in microhabitat use were found regarding gender, body size or season. Multivariate analysis revealed four macrohabitat types and showed that redfin bullies used deeper, complex macrohabitats during the day, then spread out to occupy all available macrohabitats at night. These findings have implications for river managers trying to cope with increasing anthropogenic impacts such as sedimentation.

Conservation Science Statement. The demise of New Zealand’s freshwater flora and fauna: a forgotten treasure

Biotic indices based on community composition and calculated from sensitivity scores assigned to individual taxa are commonly used as indicators for ecological integrity of fluvial ecosystems. Macroinvertebrate indices can assess water quality but invertebrate community composition also responds to other environmental factors including stream bed disturbance. This study presents a biotic community index that assesses stream bed stability in stony riffles. This Macroinvertebrate Index of Bed Stability is calibrated on transport and entrainment of in situ-marked tracer stones in 46 streams in New Zealand’s North Island, representing a wide range of substrate stability. Scores were investigated for 67 common invertebrate taxa using Indicator Species Analysis based on taxa abundance at varying levels of substrate stability. The resulting site score, weighted by taxa abundance, improved a predictive model of bed stability, generated with model trees, when added to the pool of habitat variables and explained 69% of the variation in bed stability. Site scores were strongly correlated with measured bed stability at the development sites, but not at eight independent validation sites, suggesting the need for further testing on a larger dataset including streams in other regions of New Zealand, and overseas.

Diel habitat use of two sympatric galaxiid fishes (Galaxias brevipinnis and G. postvectis) at two spatial scales in a small upland stream in Manawatu, New Zealand

Abstract Floods are an integral part of flowing river systems, yet our understanding of freshwater fish behaviour during floods is limited. In 2008, 67 redfin bullies (Gobiomorphus huttoni), 22 shortjaw kōkopu (Galaxias postvectis) and 29 kōaro (Galaxias brevipinnis) were tagged with passive integrated transponder (PIT) tags and monitored in a 100-m study reach before, during or after three floods. Detection patterns of tagged fish indicated that they may be displaced or may move to areas with large substrates during floods. Two individuals returned to the same locations during multiple floods, suggesting that previous experience may influence refuge selection for some individuals. While small changes in community composition occurred that could be attributed to concurrent habitat changes, overall a remarkable level of persistence of individual fish was observed in the tagged community.

How good are Bayesian belief networks for environmental management? A test with data from an agricultural river catchment

New Zealand’s freshwater ecosystems support a diverse and unique array of endemic flora and fauna. However, the conservation of its freshwater biodiversity is often overlooked in comparison to terrestrial and marine environments, and is under increasing threat from agricultural intensification, urbanisation, climate change, invasive species, and water abstraction. New Zealand has some of the highest levels of threatened freshwater species in the world with, for example, up to 74% of native freshwater fish listed as endangered or at risk. Threatened species are often discounted in water policy and management that is predominantly focussed on balancing water quality and economic development rather than biodiversity. We identify six clear actions to redress the balance of protecting New Zealand’s freshwater biodiversity: 1. change legislation to adequately protect native and endemic fish species and invertebrates, including those harvested commercially and recreationally; 2. protect habitat critical to the survival of New Zealand’s rare and range-restricted fish, invertebrate and plant freshwater species; 3. include river habitat to protect ecosystem health in the National Objectives Framework for the National Policy Statement for freshwater; 4. establish monitoring and recovery plans for New Zealand’s threatened freshwater invertebrate fauna; 5. develop policy and best management practices for freshwater catchments in addition to lakes and rivers to also include wetlands, estuaries, and groundwater ecosystems; and 6. establish, improve, and maintain appropriately wide riparian zones that connect across entire water catchments. We have published these recommendations as a scientific statement prepared for the Oceania Section of the Society for Conservation Biology to facilitate communication of our thoughts to as wide an audience as possible (https://conbio.org/images/content_groups/Oceania/Scientific_Statement_1_.pdf, accessed 8 February 2016).

Alien freshwater fish species in the Balkans—Vectors and pathways of introduction

Two native New Zealand galaxiid fishes [the kōaro (Galaxias brevipinnis) and the shortjaw kōkopu (Galaxias postvectis)] are declining throughout the country. More knowledge regarding aspects of their ecology is needed in order for conservation actions to be optimally designed. A 100-m reach of small upland stream in Manawatu, New Zealand was mapped to scale and inventoried for microhabitat variables. Flow velocity, depth, surface turbulence, substrate size and interstitial refuge space availability were measured in 0.25-m2 quadrats throughout the reach. Twenty-nine kōaro and 22 shortjaw kōkopu were PIT-tagged within the reach and monitored during the day (Nu2009=u200926) and night (Nu2009=u200915) in 2008 with a portable PIT monitoring system. Of these, 72xa0% of kōaro and 68xa0% of shortjaw kōkopu were detected at least once and 62xa0% of kōaro and 46xa0% of shortjaw kōkopu were detected five times or more within the study reach. During both the day and night kōaro used microhabitats that were faster-flowing, deeper, more turbulent, with larger substrate particles and more interstitial refuge spaces when compared with all microhabitats available in the reach. Shortjaw kōkopu used microhabitats with larger substrate particles and more interstitial refuge spaces when compared to all microhabitats available within the reach. During the day, shortjaw kōkopu were found in areas with larger substrates and higher surface turbulence than areas where they were found at night. Four mesohabitat types were identified in the study area using cluster analyses. Kōaro used the same flow channel-type habitats during the day and at night. Shortjaw kōkopu used flow channel and pool habitats during the day, and used pool habitats at night. These results suggest that biotic factors such as competition from shortjaw kōkopu may have been influencing kōaro habitat use patterns. In addition, these findings have implications for river managers attempting to implement conservation measures to protect these species because increasing anthropogenic impacts such as sedimentation and water abstraction can have negative impacts on instream habitat.