Effects of ultraviolet radiation on corals and other coral reef organisms

The discovery of the importance of solar ultraviolet radiation (UVR) as a factor affecting the biology of coral reefs dates only to about 1980. Interest has heightened during the past five years owing to the demonstration of loss of stratospheric ozone through human activities. We have only begun to document gross, qualitative effects of UVR on coral reef organisms, usually in experiments comparing the biological response to the presence or absence of UVR through the use of UV-cutoff filters, or to varying levels of UVR in transplantation studies. Most such studies have not distinguished between the effects of UVA (320–400 nm) and those of UVB (290–320 nm), although in the context of global change involving stratospheric ozone loss, it is the latter wavelengths that are relevant. To date we have been addressing physiological and ecological questions, not yet attempting to evaluate quantitatively the impact of forecast increases in solar UVB penetration. Interacting and synergistic effects of UVR with increased temperature, pollutants, sedimentation, visible light, etc. have scarcely been studied but will be essential to understanding and predicting the fate of coral reefs under conditions of global change. Here we comprehensively review the effects of UVR on corals and other reef macroorganisms, mindful that although much is known of proximal effects, little of this knowledge is directly useful in making long-term predictions regarding the health of coral reefs. We conclude that even small anthropogenic increases in UVB levels will have sublethal physiological manifestations in corals and other reef organisms, but that this will have relatively small impact on the distribution of reef corals and coral reefs, perhaps affecting their minimum depths of occurrence.     

A Comparison of Methods to Measure Operator Protection Factors in Open-fronted Microbiological Safety Cabinets

Comparative tests to measure operator protection factors in microbiological safety cabinets in accordance with British Standard 5726 have demonstrated good agreement in the results obtained by a microbiological method using a Collison nebulizer and the technique producing an aerosol of potassium iodide. Either method is suitable for testing for operator protection factors in Class I and Class II safety cabinets.
The Collison nebulizer should be considered as the standard aerosol generator for the microbiological method; alternative nebulizers meeting the general requirements of BS 5726 should be compared in performance with this nebulizer if they are to be used for containment tests.
Any microbiological safety cabinet specified for a new installation should have been 'type' tested to ensure compliance with BS 5726. However, in order to ensure adequate performance, on-site commissioning tests (and routine maintenance checks thereafter) are necessary to verify that air velocity, filtration and operator protection factor requirements are met.     

The white potato cyst nematode (Globodera pallida) – a critical analysis of the threat in Britain

Over the last 30 years, there has been an epidemic of the white potato cyst nematode (wPCN, Globodera pallida). It has progressively replaced the yellow species (yPCN, G. rostochiensis) throughout most of England and Wales and is now a widespread problem. As damaging populations of wPCN are enormous (>10⁹ eggs ha^?1), several crops of potato cultivars resistant only to yPCN were required to produce this change. The threat it poses is reflected in an increase in the numbers of soil samples being tested and in nematicide use, which has increased to > 25 000 ha of potatoes being treated annually. Computer modelling shows that current management of wPCN is mostly ineffective and populations will continue to increase. The multiplication rate of wPCN is inversely related to its population density at planting and, because of this, modelling shows that sufficient eggs are likely to survive to enable large populations of wPCN to “rebound” following nematicide treatment. This is supported by recent trial results showing that wPCN population increase was almost as great in nematicides‐treated plots as in the untreated. Modelling also showed that current rotations (typically potatoes once every 5 or 6 years) are too short to prevent wPCN populations from progressively increasing, even when used in conjunction with a nematicide. Similarly, except with avirulent populations, the partially resistant cultivars currently available will not prevent wPCN from increasing. However, as the effectiveness of partially resistant cultivars is independent of population density, they can be very effective when integrated with a nematicide. Unfortunately, only c. 8% of the potato area is planted with partially resistant cultivars, and much of that is in land not known to be infested with wPCN. Consequently, the current epidemic of wPCN is likely to become progressively more serious. However, many farmers are failing to recognise and respond to this threat until it is too late because of the slow rate of increase of wPCN, the difficulties of detecting small populations and the costs of nematicides. To respond to the current epidemic of wPCN, the greatest priority is to have available an increased number of commercially‐attractive partially resistant cultivars.     

The need for long-term investigations in ecology and the contribution of the Freshwater Biological Association

1. Long-term investigations have provided critical data on a number of practical issues that are of concern to society, and have made important contributions to the development and testing of ecological theory. 2. Some of the questions answered by long-term investigations are briefly reviewed. The major objectives of such investigations are usually to provide reliable estimates of base-line variation, to detect long-term trends in the mean level of the base-line, to detect rare events and to provide information for meaningful, testable hypotheses. 3. The contributions of the Freshwater Biological Association are listed in a summary table that covers all projects lasting for 20 years or longer with at least one sample per year. Most projects are in the Windermere catchment and it is proposed that the latter should become the first U.K. Long Term Reference Site for the freshwater environment.     

Factors influencing flight potential of Choristoneura conflictana

Abstract Factors affecting the flight potential of Choristoneura conflictana, an insect that undergoes cyclical changes in population density, are investigated using computer‐linked flight mills. Female and male moths are flown for a 12‐h period and the longest single flight and total flight distance of each moth is recorded. After flight bioassays, moths are subjected to lipid extraction with a soxhlet apparatus to determine the effect of body lipid content on flight. Larger C. conflictana moths fly farther than smaller moths. Female C. conflictana fly farther than male moths but the effects of both mating status and moth age on the distance flown are dependent on sex. Mated females fly farther than virgins and older females fly farther than young females but these relationships do not occur in males. Body lipid content affects the distance flown by both females and males through a significant interaction with sex and age. The factors examined in this study will vary with density in natural populations and are predicted to be important indicators of flight potential and dispersal in this species.     

The sensitivity of phytoplankton in Loch Leven (U.K.) to changes in nutrient load and water temperature

1. Loch Leven is a shallow, eutrophic lake in Scotland, U.K. It has experienced much change over the 30 years that it has been studied; this has primarily been due to reduced nutrient loads to the lake through active catchment management. Its recovery has been slow and, therefore, we used a phytoplankton community model (PROTECH) to test its sensitivity to changing nutrient loads and water temperature.
2. PROTECH was initialized to simulate the observed phytoplankton community in 1995 and was then repeatedly run through a combination of step-wise changes in water temperature and nutrient load (two treatments were simulated for nutrient load: one changing both nitrate and phosphorus, and one changing just phosphorus). The effect on total chlorophyll- a concentration, cyanobacteria abundance and phytoplankton diversity was examined.
3. Whilst changes in temperature had little effect, variations in the nutrient load produced a range of responses. Increasing only the phosphorus load caused a large increase in Anabaena abundance and total chlorophyll- a concentration. However, the opposite response was recorded when nitrate load was changed as well, with Anabaena increasing its biomass under reduced nutrient load scenarios.
4. The key factor determining the type of response appeared to be nitrogen availability. Anabaena , a nitrogen fixer, could exploit the phosphorus resource of Loch Leven under limiting nitrogen conditions, allowing it to dominate under most of the scenarios tested apart from those supplying extra nitrogen to the lake. The model predictions agree with the observed data, which show that Anabaena continues to dominate the summer phytoplankton bloom in Loch Leven despite the considerable reduction in phosphorus supply from the catchment. This research provides a possible explanation for this.