Principles and processes for effecting change in environmental management in New Zealand

In New Zealand environmental management is essentially the responsibility of land managers. Management decisions affect both production/productivity and the environment. However, responsibility for ensuring positive environmental outcomes falls on both local (Regional) and Central Government, and both they and international agencies such as the OECD would wish to monitor and report on changes. In terms of policy, strong links have been established via Central and Regional Government to land managers. Consumers in the market place are also, increasingly, requiring responsibility for positive environmental outcomes of those who purchase and process primary products. Strong links for responsibility have been established between our international markets and processing businesses and there is a noticeable strengthening of the links from the processors to the land manager/producer. In New Zealand a range of initiatives has been developed and implemented over recent times, whereby land managers are taking increasing responsibility for accounting for the environmental outcomes of their production activities. The range covers the spectrum from voluntary to compulsory (e.g., in order to meet market requirements) and from those initiated by customers to processor and/or producer initiatives. This paper follows the evolution of the principles that drove the predominant activities of the period and the processes that initiated the changes in environmental management. As the focus of agriculturalists changed from pioneering in a new world, to establishing a production base, to economic reality, and finally to environmental responsibility, the processes of extension adapted to meet the new challenge.     

How identity of the homopteran trophobiont affects sex allocation in a symbiotic plant-ant: the proximate role of food

We provide evidence for the proximate role of food in sex allocation by an ant species, and demonstrate how identity of the homopteran partner affects benefits to colonies of a plant-symbiotic ant. The system studied includes a plant-ant that nests in swollen hollowed internodes of a myrmecophyte, and two species of homopteran trophobionts (a coccid and a pseudococcid) tended inside domatia by these ants, for which they are an essential source of food. Total investment in pupae was greater for ant colonies that tended solely or primarily coccids than for those that tended pseudococcids. In particular, biomass invested in sexuals increased more rapidly with size of the colony in trees where ants tended coccids. This greater investment in sexuals was not made at the expense of investment in workers, but reflected increased resources available to coccid-tending colonies. Higher reproductive output indicates that ant fitness may be greater when they tend coccids. These additional resources led to a greater increase in production of alate females than in that of males. Consequently, the sex investment ratio of coccid-tending colonies was more female biased than in those that tended pseudococcids. Differences in resource supply affected numbers of individuals produced but not per-individual investment, with one partial exception: in very small colonies, pseudococcid-tending colonies produced small workers while coccid-tending colonies did not, further underlining the higher resource supply to coccid-tending colonies. This study provides evidence for the proximate role played by food in sex allocation at the colony level. We discuss our results in the context of hypotheses aimed at explaining sex ratio at the colony and population levels.     

Jellyfish aggregations and leatherback turtle foraging patterns in a temperate coastal environment

Leatherback turtles (Dermochelys coriacea) are obligate predators of gelatinous zooplankton. However, the spatial relationship between predator and prey remains poorly understood beyond sporadic and localized reports. To examine how jellyfish (Phylum Cnidaria: Orders Semaeostomeae and Rhizostomeae) might drive the broad-scale distribution of this wide ranging species, we employed aerial surveys to map jellyfish throughout a temperate coastal shelf area bordering the northeast Atlantic. Previously unknown, consistent aggregations of Rhizostoma octopus extending over tens of square kilometers were identified in distinct coastal "hotspots" during consecutive years (2003-2005). Examination of retrospective sightings data (>50 yr) suggested that 22.5% of leatherback distribution could be explained by these hotspots, with the inference that these coastal features may be sufficiently consistent in space and time to drive long-term foraging associations.     

Der Einsatz von Pflanzentests bei der Sedimentbewertung

Up to now, sediment studies have mainly used standardized aquatic bioassays with organisms of the three trophic levels. Among these, algae are the only representatives of the entire plant kingdom. Bioassays with higher plants have hardly been used for the assessment of sediments. The aim of the present study is to demonstrate that the use of higher plants in biotests for analyses of anthropogenically contaminated sediments yields valuable results, which may be included in a concept for the integrated assessment of waters. The contamination by environmental chemicals was determined in the River Elbe by means of samples taken at the Fahlberg-List industrial site at Magdeburg in combination with studies in a reference area on the Müritz-Elde Waterway (Eldenburger Kanal). Sediment extracts and pore waters were tested with the aquatic lemna test. For comparison, first sediment contact tests withLemna minor were tried out. The whole extract of the sediment from Fahlberg-List Magdeburg and one fraction F5 caused distinct damages of the plants. Obviously, the phytotoxic substances of the whole extract are preferentially concentrated in the highly polar fraction F5. A comparison with chemical analytical data proved that the whole fraction F0 and the fraction F5 were heavily contaminated with chemicals. Assays with pore water from this sediment and with the whole sediment also caused a strong inhibition of growth. These results confirm the high contamination of the sediment from Magdeburg. The tests with the reference sediment suggested only a moderate toxic contamination. The results of this study prove that the selected aquatic plant,Lemna minor, is basically able to indicate contamination. In the aquatic test of the sediment extracts, it showed weak, but very selective, responses to certain classes of contaminants. Fractionating of the sample and subsequent chemical analysis combined with toxicity tests allow to narrow down the groups of substances causing toxic effects. This toxicity was confirmed by analyses of the pore waters and whole sediment samples. Together with other toxicity tests (e.g. standardized bioassays) and combined with biological benthos examinations, an overall judgment can be given for the integrated assessment of waters.     

Willow on Yellowstone's northern range: evidence for a trophic cascade?

Reintroduction of wolves (Canis lupus) to Yellowstone National Park in 1995-1996 has been argued to promote a trophic cascade by altering elk (Cervus elaphus) density, habitat-selection patterns, and behavior that, in turn, could lead to changes within the plant communities used by elk. We sampled two species of willow (Salix boothii and S. geyeriana) on the northern winter range to determine whether (1) there was quantitative evidence of increased willow growth following wolf reintroduction, (2) browsing by elk affected willow growth, and (3) any increase in growth observed was greater than that expected by climatic and hydrological factors alone, thereby indicating a trophic cascade caused by wolves. Using stem sectioning techniques to quantify historical growth patterns we found an approximately twofold increase in stem growth-ring area following wolf reintroduction for both species of willow. This increase could not be explained by climate and hydrological factors alone; the presence of wolves on the landscape was a significant predictor of stem growth above and beyond these abiotic factors. Growth-ring area was positively correlated with the previous year's ring area and negatively correlated with the percentage of twigs browsed from the stem during the winter preceding growth, indicating that elk browse impeded stem growth. Our results are consistent with the hypothesis of a behaviorally mediated trophic cascade on Yellowstone's northern winter range following wolf reintroduction. We suggest that the community-altering effects of wolf restoration are an endorsement of ecological-process management in Yellowstone National Park.     

Integrating phenological, chemical and biotic defences in ant-plant protection mutualisms: a case study of two myrmecophyte lineages

Summary. We examined the role of plant phenology in the evolution of anti-herbivore defence in symbiotic ant-plant protection mutualisms. Phenology of the host-plant affects traits of its herbivores, including size, growth rate, development time, and gregariousness. Traits of herbivores in turn determine what traits ants must have to protect their host. Diversity in plant phenological traits could thus help explain the great ecological diversity of coevolved ant-plant mutualisms. We explored the postulated causal chain linking phenology of the plant, herbivore adaptations to phenology, and ant adaptations for protection, by comparing two myrmecophytes presenting strong contrasts in phenology. In Leonardoxa africana, a slow-growing understory tree, growth at each twig terminal is intermittent, the rapid flushing of a single leaf-bearing internode being followed by a pause of several months. In contrast, axes of Barteria nigritana, a tree of open areas, grow continuously. Analysis of the phenology (kinetics of expansion) and chemistry of leaf development (contents of chlorophylls, lignin, and nitrogen during leaf growth) showed that these two species exhibit strongly contrasting strategies. Leonardoxa exhibited a delayed greening strategy, with rapid expansion of leaves during a short period, followed by synthesis of chlorophylls and lignins only after final leaf size has been reached. In contrast, leaves of Barteria expanded more slowly, with chlorophylls and lignin gradually synthesised throughout development. Differences in the phenology of leaf development are reflected in differences in the duration of larval development, and thereby in size, of the principal lepidopteran herbivores observed on these two plants. This difference may in turn have led to different requirements for effective defence by ants. The strategy of phenological defence may thus affect the evolution of biotic defence.     

Communicating the risk from radon.

A prominent television station developed a special series of newscasts and public service announcements about radon. This was combined with their advertising of the availability of reduced-price radon test kits in a local supermarket chain. The large number of test kits sold was a success from a marketing perspective, but not from a public health perspective--especially because of the very small share of high readings that were mitigated. In contrast, a study of housing sales showed a much higher testing rate and corresponding mitigation when risk communication accompanied the housing transaction, rather than being directed toward the general public. This paper examines the relative effectiveness of these alternative approaches to radon risk communication, emphasizing the implications for developing and implementing radon programs.     

Biological solids reduction using the Cannibal process.

A laboratory study of the Cannibal process was undertaken to determine if the Cannibal system would generate less sludge compared with a conventional activated sludge system. Side-by-side sequencing batch reactors were operated--one using the Cannibal configuration and the other as conventional activated sludge. It was found that the Cannibal process generated 60% less solids than the conventional activated sludge system, without any negative effect on the effluent quality or the settling characteristics of the activated sludge. The oxygen uptake rate for the centrate from the Cannibal bioreactor showed that readily biodegradable organic matter was released from the recycled biomass in the Cannibal bioreactor. It is proposed that the mechanism for reduced solids from the Cannibal system is that, in the Cannibal bioreactor, iron is reduced, releasing iron-bound organic material into solution. When the Cannibal biomass is recirculated back to the aeration basin, the released organic material is rapidly degraded.