Low-dose alum application trialled as a management tool for internal nutrient loads in Lake Okaro, New Zealand

Aluminium sulfate (alum) was applied to Lake Okaro, a eutrophic New Zealand lake with recurrent cyanobacterial blooms, to evaluate its suitability for reducing trophic status and bloom frequency. The dose yielded 0.6 g aluminium m–3 in the epilimnion. Before dosing, pH exceeded 8 in epilimnetic waters but was optimal for flocculation (6–8) below 4 m depth. After dosing, there was no significant change in water clarity, hypolimnetic pH decreased to 5.5, and soluble aluminium exceeded recommended guidelines for protection of freshwater organisms. Epilimnetic phosphate concentrations decreased from 40 to 5 mg m–3 and total nitrogen (TN):total phosphorus (TP) mass ratios increased from 7:1 to 37:1. The dominant phytoplankton species changed from Anabaena spp. before dosing, to Ceratium hirudinella , then Staurastrum sp. after dosing. Detection of effectiveness of dosing may have been limited by sampling duration and design, as well as the low alum dose. The decrease in hypolimnetic pH and epilimnetic TP, and increase in Al3+ and chlorophyll a, are attributed to the low alkalinity lake water and coincidence of alum dosing with a cyanobacterial bloom and high pH

Quantifying temporal and spatial variations in sediment, nitrogen and phosphorus transport in stream inflows to a large eutrophic lake

High-frequency sampling of two major stream inflows to a large eutrophic lake (Lake Rotorua, New Zealand) was conducted to measure inputs of total suspended sediment (TSS), and fractions of nitrogen and phosphorus (P). A total of 17 rain events were sampled, including three during which both streams were simultaneously monitored to quantify how concentration–discharge (Q) relationships varied between catchments during similar hydrological conditions. Dissolved inorganic nitrogen (DIN) concentrations declined slightly during events, reflecting dilution of groundwater inputs by rainfall, whereas dissolved inorganic P (PO₄–P) concentrations were variable and unrelated to Q, suggesting dynamic sorptive behaviour. Event loads of total nitrogen (TN) were predominantly DIN, which is available for immediate uptake by primary producers, whereas total phosphorus (TP) loads predominantly comprised particulate P (less labile). Positive correlations between Q and concentrations of TP (and to a lesser extent TN) reflected increased particulate nutrient concentrations at high flows. Consequently, load estimates based on hourly Q during storm events and concentrations of routine monthly samples (mostly base flow) under-estimated TN and TP loads by an average of 19% and 40% respectively. Hysteresis with Q was commonly observed and inclusion of hydrological variables that reflect Q history in regression models improved predictions of TN and TP concentrations. Lorenz curves describing the proportions of cumulative load versus cumulative time quantified temporal inequality in loading. In the two study streams, 50% of estimated two-year loads of TN, TP and TSS were transported in 202–207, 76–126 and 1–8 days respectively. This study quantifies how hydrological and landscape factors can interact to influence pollutant flux at the catchment scale and highlights the importance of including storm transfers in lake loading estimates

Use of high-intensity data to define large river management units: A case study on the lower Waikato River, New Zealand

The importance of environmental heterogeneity in lotic ecosystems is well recognised in river management, and continues to underpin studies of hierarchical patch dynamics, geomorphology and landscape ecology. We evaluated how physical characteristics and water chemistry measurements at high spatiotemporal resolution define channel units of potential ecological importance along 134 km of the lower Waikato River in North Island, New Zealand. We used multivariate hierarchical clustering to classify river reaches in an a priori unstructured manner based on (i) high-frequency, along-river water quality measurements collected in four seasons and (ii) river channel morphology data resolved from aerial photos for 1-km long reaches. Patterns of channel character were shaped by the depth and lateral complexity of constituent river reaches, while water quality patterns were represented by differences in clarity, chlorophyll fluorescence and specific conductance driven by tributary inflows in the mid-section of the river and tidal cycles in the lower section. Management units defined by physical characteristics or water quality did not necessarily align with boundaries typically reflecting clinal processes (e.g. tidal influence) or geomorphic, network or anthropogenic discontinuities. The results highlight the dynamic spatial and temporal properties of large rivers and the need to define clear objectives when deriving spatial units for management and research. Given that actions and targets for physical channel and water quality management may differ, the spatial extent identified for each of these does not necessarily need to directly coincide, although both should be considered in decision making and experimental design

CLIMATE CHANGE AND INTERNATIONAL TOURISM: A SIMULATION STUDY

The literature on tourism and climate change lacks an analysis of the global changes in tourism demand. Here a simulation model of international tourism is presented that fills that gap. The current pattern of international tourist flows is modelled using 1995 data on departures and arrivals for 207 countries. Using this basic model the impact on arrivals and departures through changes in population, per capita income and climate change are analysed. In the medium to long term, tourism will grow, however the growth from climate change is smaller than for population and income changes.Tourism demand, climate change, global model

THE EFFECTS OF CLIMATE CHANGE ON INTERNATIONAL TOURISM

We present a simulation model of the flow of tourists between 207 countries. The model almost perfectly reproduces the calibration year 1995, and performs well in reproducing the observations for 1980, 1985 and 1990. The model is used to generate scenarios of international tourist departures and arrivals for the period 2000-2075, with particular emphasis on climate change. The growth rate of international tourism is projected to increase over the coming decades, but may slow down later in the century as demand for travel saturates. Emissions of carbon dioxide would increase fast as well. With climate change, preferred destinations would shift to higher latitudes and altitudes. Tourists from temperate climates would spend more holidays in their home countries. As such tourists currently dominate the international tourism market, climate change would decrease worldwide tourism. The effects of climate change, however, are small compared to the baseline projections.International tourism, climate change impacts, carbon dioxide emissions, scenarios

Climate preferences and destination choice: a segmentation approach

A data set of the holiday destination choices of German tourists is segmented using phase in the life cycle; second, holiday motivation and holiday activities and third, the region of residency. For each segment demand is estimated using data on environmental and economic characteristics of countries. The optimal temperature, where demand peaks, ranges from 22°C to 24°C across the segments. More interestingly, the steepness of the temperature demand relationship is different for different segments. Even though the temperature optima are similar, changes in temperature, for example caused by climate change will have a larger effect on demand depending on the steepness of the temperature-demand relationship. A climate index is calculated for each country using climate data and the respective coefficients from the estimated demand equations. The climate index values are different across the segments: the segment containing those tourists who were swimming and sunbathing while on holiday has the highest index values of all of the segments.tourism demand, segmentation, climate preferences

Restoration of Lake Hakanoa: Results of model simulations

This report was requested by Waikato District Council. It covers the lake water quality of, and possible restoration scenarios for, Lake Hakanoa a riverine lake situated in Huntly. The lake is used as a recreational resource by the community. In the past it has been reported to have had very poor water quality and is known to be eutrophic. It is currently in an algal-dominated, devegetated state and has low water clarity. The shallowness of this lake makes it potentially susceptible to resuspension of sediments through wind action. A community group, Friends of Hakanoa, has been responsible for the formation of a path around the perimeter of the lake, retiring about 3.6% of the catchment from pastoral farming and creating a riparian margin. Results from more recent reports and this report indicate a trend of improving water quality which may be related to recent restoration actions such as re-establishment of a riparian margin

Knowledge, documentation and a London location

Purpose – As documents, and the whole information and communication environment, become increasingly digital, it is natural to assume that physical location becomes of less importance. The aim of this paper is to highlight two newly published books, which remind us that this idea should be examined with a critical eye. Design/methodology/approach – This editorial takes the form of a literature review and a viewpoint. Findings – The paper finds books of this kind remind us that a physical place, a locality, has sometimes been a very powerful stimulus to the development of collections, of memory institutions, and of the advances in education and dissemination of knowledge which are associated with them. This is worth remembering as we move into a digital information world. Originality/value – The paper offers the author's viewpoint as well as highlighting these two books which join a small number which have analysed and celebrated the history of intellectual advances in London

Restoring O’Brien Creek, Missoula, MT

O’Brien Creek, near Missoula, Montana, has been altered by tree harvest, road building, grazing and dewatering. These actions led to loss of streamside vegetation, increased streambank erosion and scouring, and decreased native fish and wildlife recruitment. The Forest Service recently closed and recontoured roads in the upper watershed while the Montana Department of Fish, Wildlife and Parks regraded and revegetated the lower creek to return it to a more natural state. I monitored the efficacy of revegetation of the newly restructured streambanks within the first year and a half of planting. The survival rate of plantings after the first year was only 25%, due, most probably, to the small size of the plants, competition with exotic weeds, and the placement of the plants well above the mid-summer water table. I recommend larger plants, placed with their roots in the mid-summer water table, and an effort to control weeds near the plantings. The restoration of O’Brien creek was done in patchwork fashion, with 2 agencies working on separate projects in different areas of the watershed without much coordination. Greater coordination and cooperation between agencies will likely result in more efficient and successful restoration efforts. However, the agencies are to be commended for their efforts which are already producing increases in fish populations in the creek