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The flash-stimulated luminescent response (FSLR) of euphausiids is a useful tool for the investigation of their bioluminescent behaviour. This paper describes the investigation of the effects of temperature upon a series of such FSLRs produced in individuals of Thysanoessa raschi (M. Sars) by three stimulations with an electronic photofiash at 20 min intervals. The following parameters of the response were measured: responsedelay, responseduration, the sum of these two {delay + duration) and the proportion of stimulations which produced a response. Initial experiments showed that all response delays were significantly different at 10°C and at 5°C, while second andthird response delays were not different from each other. The effect of a range of temperatures from 0° to 20°C on FSLR delay and duration is described. Regression lines based on the Arrhenius equation were fitted to the results. These showed that all response parameters decreased with increasing temperature, although Q10 varied from — 7.8 in the case of thefirst response delay to — 1.3 in the case of second/third response delay. This difference was the most marked effect of the second stimulation; the third stimulation caused no additional change. Below 10°C the second delay was shorter than the first delay. The independent response parameters were found to be delay and delay + duration. Duration resulted from the interaction of these two. These results are discussed and compared with the interpretation of the results of similar experiments by Kay (1965, 1966) onMeganyctiphanes norvegica.

INTRODUCTIONDinoflagellates have often been held responsible for a large part of the phosphorescence of the surface waters of the sea. In temperate waters, dinoflagellates are seldom the most abundant constituents of the phytoplankton, and until recently little experimental evidence has been available to support this assertion. Until recently there have been few careful attempts to determine which particular species of dinoflagellates are luminescent, or to relate total luminescence to numbers of dinoflagellates present.

Petroleum as it occurs in Nature is a very complex mixture of hydrocarbons. Imagine a mixture of petrol, paraffin, gas oil, fuel oil and lubricating oil, together with a certain amount of water and other foreign matter, and you have an idea of crude petroleum as it is found in Nature.It is interesting to note that practically the sole use of petroleum for some time after the first well was drilled was as a burning oil. The object of the refiner was therefore to produce as large as possible a percentage of paraffin from his crude. The lighter fractions were regarded as a necessary evil, and it became a very difficult problem to dispose of them satisfactorily. It was, of course, necessary to keep the flash point of the paraffin high enough to avoid the danger of explosion of the lamps in which it was used. Petroleum inspectors were employed to ensure that the paraffin on sale was not “adulterated” with the then valueless light petroleum spirit. No market other than as a source for lighting gas was found for this light spirit until the advent of the motor car.

The euphausiid Thysanoessa raschii (M. Sars) rarely luminesces spontaneously in the laboratory. The flash-stimulated luminescent response (FSLR) was therefore used to investigate seasonal changes in luminescent ability. Some observations were also made on the responsiveness of Meganyctiphanes norvegica. In the case of T. raschii both sexes showed maximum responsiveness from March through June and in some years to September. The strength of the tendency to respond was strongest in May and June. The FSLR delay was least during April, May and June. These results are interpreted in the light of the hypothesis that the form of the FSLR is the result of opposing inhibitory and excitatory components. It is tentatively concluded that luminescence is involved in behaviour related to spermatophore transference, which takes place from April to June.

An attempt has been made to use sample estimates of the three parameters of the truncated continuous log-normal distribution as descriptive macroscopic statistics for the diversity and abundance of phytoplankton populations from the Firth of Lorne and Loch Etive on the west coast of Scotland. A log-normal model was found to provide a reasonable description of the distribution of entily 1 abundances in most samples. Sample estimates of median abundance, total number of entities in the population, and standard deviation, as well as of the total phytoplankton abundance, were used to describe changes taking place in the population at the station in the Firth of Lorne during the course of a year from June 1970 to June 1971, and to compare the populations of the upper and lower basins of Loch Etive during May to November 1970. An attempt has been made to explain the ecological meaning of the statistics and, in the case of the Loch Etive samples, to explain differences between values for the populations from the two basins resulting from the effects of a lower and more variable salinity in the upper basin.

Si descrive un metodo per determinare il contenuto di anidride carbonica dell'acqua, che prevede il passaggio del CO2 dall'acqua attraverso una membrana di lattice ad una soluzione alcalina dove la variazione di conduttivita e radioattivita viene misurata e usata per calcolare il livello di CO2 del campione d'acqua.

One of us (Gage 1972a) has examined the diversity of the macrobenthos of Loch Etive, Loch Creran and the Firth of Lorne on the west coast of Scotland, using the rarefaction method of Sanders (1968). The other (Tett 1973) has attempted to characterize the abundance and diversity of phytoplankton populations from Loch Etive and the Firth of Lorne by means of estimates of the parameters of a log-normal model fitted to sample distributions of taxon abundances. Although Lie (1969) has shown that the abundances distribution of infaunal benthic species from Puget Sound correspond reasonably well to a truncated log-normal distribution, there is no convincing theoretical reason why this should be so. In the case of phytoplankton populations the origin of a log-normal distribution can be explained, theoretically, in terms of simple processes of exponential growth (see e.g. Macarthur 1960). It was thus of interest to test the application of the log-normal distribution to further benthic data, by use of techniques based on the method of Hald (1949) for estimating the parameters of a truncated normal distribution. It was further hoped that it might be possible to make use of log-normal statistics to compare macrobenthic populations in the same way as Tett (1972) compared phytoplankton populations. Two different approaches have become apparent in community ecology (see e.g. Pielou 1969; Hurlbert 1971); The first consists of representing a community characteristic, for example diversity, in terms of a parameter of a fitted theoretical model. The use of the log series a (Fisher, Corbet & Williams 1943), and the use of log-normal statistics, are examples of this approach. The second approach consists of the use of empirical methods, which, it is claimed, are independent of a priori assumptions about the structure of the community studied. Examples of this approach are the use of the indices proposed by Hurlbert (1971) and the Sanders (1968) rarefaction method. Similar virtues have been claimed for the various information statistics (see e.g. Margalef 1958 and Pielou 1969), but whether they are independent of a priori assumptions is arguable. By attempting to use log-normal statistics to describe the same populations as Gage (1972a) has analysed with Sanders' rarefaction method, it was hoped that a useful comparison between the two approaches could be made