Description and forecast of summer climate in physiologically significant terms

The Discomfort Index (DI) was found to be an accurate expression of the atmospheric evaporative (cooling) power, and hence the heat load. It conveys the relevant climatic conditions in summer in physiologically significant terms. From 22–24 units a slight heat load exists, from 24.1–28 the heat load is moderate and above 28.1 a severe heat load exists. The heat load during the month of August was analyzed for 2 towns in Israel: Tel-Aviv (in the coastal plain) and Beer-Sheba (in the northern part of the desert). On the basis of this example a method is suggested to express summer climate as daily hours of heat load. Information about heat stress can be conveyed in terms which are sïgnificant physiologically and meaningful to the public.     

Non-reproductive determination of 'migratory' flight in Argentine stem weevils, Listronotus bonariensis

ABSTRACT. The seasonal flight activity of Listronotus bonariensis (Kuschel) between 1976 and 1978 in Canterbury, New Zealand, is described and, in the light of current thinking, interpreted as migratory. Flight intensity appeared to be closely linked to prevailing weather conditions and unrelated to sexual activity. Furthermore, during the summer months a large proportion of flying weevils were gravid, and at the onset of hibernatory diapause flight continued unabated until the occurrence of cold winter conditions. These results indicate none of the energy partitioning often observed in other insect species where reproductive and migratory effort are mutually exclusive.     

Throughfall,stemflow and interception of rainwater in an evergreen broadleaved forest

In order to analyze the dyanmics of heavy metals in a forest ecosystem, throughfall and stemflow were collected for individual rain showers in an evergreen broad-leaved forest dominated byCastanopsis cuspidata. The relation between throughfall (or stemflow) (Px) and gross rainfall (P) was approximated by a linear regression equationPx=a(P-b). The values of coefficient “a” were 0.32–2.02 for throughfall at each sampling point and the mean values for 1976 and 1977–1978 were 0.682 and 0.767, respectively. The stemflow volume differed widely among individual trees, depending mainly on the tree form of each species. In particular, the tree form ofPasania edulis was found to be especially suited to collecting stemflow. OneP. edulis tree collected 64% of the rainwater that fell onto its crown as stemflow. The ratio of stemflow to gross rainfall decreased in summer resulting from an increase in leaf biomass and an increase in air temperature. In fact, the values of coefficient “a” for mean stemflow per unit area were 0.180 for summer and 0.229 for other seasons in 1976, and 0.145 for summer and 0.155 for other seasons in 1977–1978 for different sampled trees.     

Activity patterns of female red deer (Cervus elaphus L.) in the Alps

Summary During 1976 to 1978 in the Bavarian Alps (Southern West Germany) the activity patterns of nine female red deer have been studied using radio-telemetry. The daily sum total of activity shows a marked annual cycle, ranging from about 7 h in winter to some 15 h in summer. It becomes obvious that the duration of activity during solar day, night and twilight is not only due to the length of these three periods but also varies independently in the course of the year. The daily pattern of activity reveals a bimodal 24-h rhythm throughout the year. Its two peaks coincide with dawn and dusk. Their temporal position shifts according to the seasonally changing LD-ratio. Also the relative height of the two peaks varies in the course of the year; they decrease in the summer months in favour of more activity during the light time. These daily and annual rhythms rely on corresponding changes in the pattern of activity bursts. In some cases the sequences of activity bursts reflect also influences of weather conditions or of differently structured habitats on the animals' behaviour. The possible influences of some endogenous and exogenous factors on the activity patterns are discussed.     

Regulation of rotifer densities by crustacean zooplankton in an oligotrophic montane lake in British Columbia

Summary To examine the relative demographic effects of predation and competition for food in rotifers during spring and summer in an oligotrophic lake, predator and competitor densities and food supplies were experimentally altered inside large enclosures. Abundances of rotifer species were positively correlated with experimental densities of fourth instar Chaoborus trivittatus larvae, a major crustacean predator in 1976. Experimental alteration of the densities of Daphnia rosea and Diaptomus leptopus and D. kenai in 1978 produced highly significant increases in rotifer biomass only under Daphnia removal, but not under copepod removal. Inorganic fertilizer additions to enclosures in 1978 and 1979 revealed minimal rotifer increases unless pulsed additions were large or Daphnia were also excluded. Large demographic reponses of rotifers to low fertilizer loadings in the absence of Daphnia confirmed the pre-eminence of competitive food limitation in producing rotifer scarcity in summer.     

Interactions between phytoplankton and zooplankton in a fertilized lake

The limnology of an oligotrophic lake, Langvatn, situated in Trøndelag county in Central Norway, has been studied for five years (1974–1978). In two years, 1975 and 1976, the lake was fertilized with a general fertilizer to change feeding conditions for the zooplankton. Mean phytoplankton biomass in the epilimnion and primary production for the years (1974–1978) were 417, 618, 1370, 607 and 779 mg m⁻³ and 10.6, 22.2, 49.0, 26.8 and 17.7 g C m⁻² yr⁻¹, respectively. Cladocerans were the dominant herbivore group in 1974 and 1975 and Rotifera in the next three years. The main difference in the interaction between phytoplankton and zooplankton occurred when cladoceran dominance gave way to rotifer dominance. Heavy phytoplankton grazing by cladocerans in 1974 and 1975 stabilized the biomass and maintained it at a low level, which also resulted in a relatively low primary production. The rotifer-dominated community during the years 1976–1978 did not possess the ability to maintain a stable level of algal biomass. Primary production was also relatively high during these years.     

The effect of fiber characteristics on thermoregulatory responses and feeding behavior of heat stressed cows

We examined the effect of replacing wheat hay with soy hulls on thermoregulatory responses and feeding behavior under summer condition in dairy cows. Milk yield, feed intake, meal size, and number, heart rate and heat production were similar in the two dietary groups. Visit duration and time spent eating were shorter, and body temperature was higher in the soy hulls fed cows. It was concluded that supplying soy hulls can enable cows subjected to heat load conditions to reduce the costs of feed ingestion. However, the contribution of this tool to the overall energy budget is rather small.     

Studies on the seed-borne phases of dark leaf spot Alternaria brassicicola and grey leaf spot Alternaria brassicaeof brassicas

Tests in Britain on samples of basic and commercial Brassica oleracea seed between 1976 and 1978 showed that many lots were infected with Alternaria brassicicola. A. brassicae was uncommon in basic seed in these years and in commercial seed harvested in 1976 and 1977 but was frequent in seed harvested in 1978. Most affected seeds were contaminated by surface-borne spores and mycelium of A. brassicicola but many were internally infected by the fungus situated within the seed-coat and in some seeds in the embryo tissues. Superficial contamination by the fungus declined rapidly after 2 yr in cabbage seeds stored at 10 °C, 50% r.h. but internal infection persisted for up to 12 yr. In some samples, internal infection was commonly associated with small shrivelled seeds. Surface contaminated and internally infected seeds transmitted the disease but seedling infection was more closely correlated with the latter.     

Zur Rolle des Pektins bei der Ausprägung sorten- und jahresbedingter Unterschiede der Naßfäuleanfälligkeit von Kartoffelknollen

The influence of soil moisture and mean day temperature of July to September on pectin structure and soft rot resistance of potato tubers was investigated. Tuber samples of middle early and middle late potato cultivars respectively were tested from 1976 to 1979. Cultivar characteristics as well as growth conditions effect the pectin structure. The tuber tissue of soft rot resistant cultivars contains relative high amounts of esterified pectin. The pectin esterification was promoted by drought during vegetation periods (1976, 1978). A late rise of metabolic activity caused by rainfall at the end of the vegetation period (1978) increased the amount of soluble pectin in the cell wall. This lack of pectin stabilization facilitates tissue maceration by soft rot bacteria. Increased pectin solubility was also caused by unfavorable storing conditions of potato tubers. A low degree of esterification and high solubility of the cell wall pectin affect the relative resistance of potato tubers against soft rot caused by Erwinia carotovora var. atro-septica (van Hall) Dye adversely.     

Interactions between zooplankton and fish in a fertilized lake

The effects of fish predation on the zooplankton community in an oligotrophic lake, Langvatn, near Trondheim in Central Norway, were investigated during a six-year period (1973–1978), together with the added effects of changes produced by adding artificial fertilizer in 1975 and 1976. The improved nutrient conditions in 1975 resulted in a rapid increase in biomass and production of the largest herbivore zooplankton species and of the fish population. A change in the behaviour and food habits of the arctic char was recorded; they became more pelagic and fed mainly on zooplankton. An increased survival rate of 0-group and biomass of planktivorous fish in 1975 enhanced the degree of fish predation on the zooplankton during subsequent years (1976–1978). As a consequence of fish predation, the composition of the zooplankton changed, from a mainly large-sized to a mainly small-sized community, dominated by Bosmina longirostris and rotifers. Since fish predation is size-selective and visibility-dependent, it induced a decrease in mean size and in body length at onset of maturity of the cladoceran populations and probably also weakened their ability to produce resting eggs.     

The role of storms in the summer succession of the phytoplankton community in a shallow lake (Lake Balaton, Hungary)

The authors carried out day-to-day studies on the phytoplanktonof the largest shallow lake of Central Europe in the summerof 1976, 1977 and 1978. Data were analysed with diversity andcluster analyses. (i) Wind-induced stirring-up of the sedimentplays important role in the summer phytoplankton successionof the shallow lake. (ii) After storms algae with very smallcell sizes show synchronous development. In long calm periodsalgae with larger cell sizes exhibit organised population dynamics.(iii) In calm periods a shift from r-selection to predominantK-selection can be suspected. After the next storm importanceof r-selectionists again increases. (iv) Effect of changinggrowth- and loss rates on the population dynamics of the mostabundant species is discussed based on measured generation timesand calculated elimination. The phenomena discussed in the papercan appear to different extents in the summer phytoplanktonsuccession of other shallow, polimictic lakes.     

Besprechungen/Reviews

Book reviewed in this article: Lindauer, M. (1976): Orientierung der Tiere Papi, F. (1976): The olfactory navigation system of the homing pigeon (Das Heimfinden der Taube mit Hilfe ihres geruchlichen Navigationssystems) Lang, H.-J. , und H. Zierau (1976): Beeinflussung der Farbempfindlichkeit durch akustische Reize beim Guppy (Lebistes reticulatus) Kramer, B. (1976): Kommunikation bei schwach elektrischen Fischen (Gnathonemus petersii, Mormyridae) Wiltschko, R. , und W. Wiltschko (1976): Der Einfluz? von Magnetfeld und Sternen auf das Orientierungsverhalten von Zugvögeln im Rundkäfig Schäfer, W. M. , und M. Quinten (1976): Zur “Händigkeit” und LabyrinthOrientierung weiz?er Mäuse Eisner, N. , und O. v. Helversen (1976): Altersbedingte Abwandlungen der Stridulationsmuster bei Feldheuschrecken Obert, H.-J. (1977): Etho-endokrinologische Untersuchungen zur Bedeutung der Paarungsrufe von Rotbauchunken Brackbill, H. (1978): Play by Ring-billed Gulls (Spielende Aztekenmöwen) Lamprecht, J. (1978): On diet, foraging behaviour and interspecific food competition of jackals in the Serengeti National Park, East Africa Sailler, H. , und U. Schmidt (1978): Die sozialen Laute der Gemeinen Vampirfledermaus Desmodus rotundus bei Konfrontation am Futterplatz unter experimentellen Bedingungen Herzig-Straschil, B. (1978): On the biology of Xerus inauris Apfelbach, R. (1978): A sensitive phase for the development of olfactory preference in ferrets, Mustela putorius Whateley, A. , und P. M. Brooks (1978): Numbers and movements of spotted hyaenas in Hluhluwe Game Reserve Tichy, H., ed. (1978): Kenia. Umschau Verlag, Frankfurt Schneider, F. (1977): Die Bestimmung der Länge von “Gravitationswellen” mit sinnesphysiologischen Methoden und weitere Beweise für ultraoptisch determiniertes Verhalten nach Ausschluz? richtungsweisender magnetischer Felder     

A survey of cutworm attacks in England and Wales, and a descriptive population model for Agrotis segetum (Lepidoptera: Noctuidae)

Surveys of larval populations and numbers of reports of damage showed that from 1945 to 1978 Agrotis segetum was the commonest species of cutworm, causing most damage, to a wide range of crops, from July to October. Attacks varied in extent and severity between years, the most severe damage occurring in 1949 and in 1976. A model has been devised to estimate an index of larval survival to third instar, based on temperature-rate of development relationships and mortality due to daily rainfall. This survival index is highly correlated with year-to-year changes in numbers of reported attacks by A. segetum. The model suggests that weather conditions alone were responsible for the last major cutworm outbreak in 1976.     

The maximum leaf surface temperatures of the higher plants observed in the Inland Sea area

The maximum leaf surface temperatures (MLSTs) of 126 species of higher plants were measured by means of an infrared thermometer, in the Inland Sea area, southwest of Honshu-Island, Japan, where plants suffered from severe environmental conditions due to an abnormally small amount of precipitation during the summer of 1978. The MLSTs of plants in the summer of 1978 were greater than or equal to those of 1979, when the environmental conditions were not so severe. The MLST measured in this study was 50.4 C for a non-succulent plant (Liriodendron), and 53.1 C for a succulent plant (Agave). Plants with different life forms appeared to have different MLSTs. The average of the MLSTs of conifers deciduous trees, and evergreens were 36.4, 37.7, and 40.3 C, respectively. This order corresponds to the distribution of forests from high to low, latitudes. Also the MLSTs were higher for woody plants than for herbaceous plants. Relatively high leaf temperatures were observed for climbing plants, both herbaceous and woody. Plants with narrow leaves had lower leaf surface temperatures than those with borad leaves. Herbaceous dicotyledonous plants actively growing at the end of the summer of 1978, in full sun at Hiroshima Castle were exclusively those with relatively high leaf temperatures.     

The influence of climatic conditions on long-term changes in the helminth fauna of terrestrial molluscs and the implications for parasite transmission in southern England

The influence of climatic conditions on the prevalence and transmission of helminth parasites in a terrestrial mollusc population was studied in a grassland site in southern England between 1974 and 1983. Molluscs were sampled in each September of 5 years over this period (1974, 1976, 1979, 1981, 1983). Climatic conditions had a variable effect on parasite prevalence. Trematode sporocyst infections increased after wet summer and warm winter conditions and declined in hot, dry periods. Cestode infections increased after combined wet spring and summer weather and low winter temperatures, although trematode metacercariae and nematode infections were less likely to be influenced by climate. The effects on parasite transmission were undertaken by comparing parasite prevalences in the principal definitive hosts, the common shrew (Sorex araneus) and the wood mouse (Apodemus sylvaticus) in the same habitat over the period 1973-1983. Changes in parasite prevalences in the molluscan population were rarely replicated by changes in the small mammal population, except for trematode parasites in small mammals during a period of severe drought in 1976. These results suggest that only long-term persistent modifications in climate are likely to affect host-parasite dynamics.     

Interspecific dominance amongst three species of coarse fish in Slapton Ley, Devon

Marked changes in the relative numbers of roach Rutilus rulilus (L.), rudd Scardinius erylhroplhalmus (L.) and perch Perca fIuviatilis L. , in Slapton Ley, Devon, have been observed over the period 1967–1978. Historically, the lake had been dominated by rudd and perch; significant numbers of roach were not thought to be present until 1967. From then onwards the roach population exhibited a considerable expansion, apparently replacing the rudd, which had virtually disappeared by 1974. In 1975 extensive mortalities of roach were caused by the pseudophyllidean cestode Ligula intestinalis L. During 1976 and 1977 larger number of rudd, belonging to the 1975 and 1976 year classes, were present, suggesting that the roach mortalities might be giving the rudd a chance to recover. However, very few rudd were present during 1978, possibly because lower incidences of ligulosis during 1976–1978 had allowed the roach to recover from the main outbreak of the disease in 1975, and to replace the rudd for the second time. Evidence from trap catches indicated that the perch population had shown a consistent decline between 1970 and 1977. The major phase of this decrease occurred between 1971 and 1973, when the roach population was increasing the most rapidly. Comparisons were made with changes in fish populations in other localities. The major reason for the changes observed was thought to be a competitive relationship between the plankton feeding younger stages, with roach being the dominant species, although other factors may also have been involved.     

The impact of rising temperatures on the prevalence of coral diseases and its predictability: A global meta-analysis

Coral reefs are under threat from disease as climate change alters environmental conditions. Rising temperatures exacerbate coral disease, but this relationship is likely complex as other factors also influence coral disease prevalence. To better understand this relationship, we meta-analytically examined 108 studies for changes in global coral disease over time alongside temperature, expressed using average summer sea surface temperature (SST) and cumulative heat stress as weekly sea surface temperature anomalies (WSSTAs). We found that both rising average summer SST and WSSTA were associated with global increases in the mean and variability in coral disease prevalence. Global coral disease prevalence tripled, reaching 9.92% in the 25 years examined, and the effect of ‘year’ became more stable (i.e. prevalence has lower variance over time), contrasting the effects of the two temperature stressors. Regional patterns diverged over time and differed in response to average summer SST. Our model predicted that, under the same trajectory, 76.8% of corals would be diseased globally by 2100, even assuming moderate average summer SST and WSSTA. These results highlight the need for urgent action to mitigate coral disease. Mitigating the impact of rising ocean temperatures on coral disease is a complex challenge requiring global discussion and further study.     

Antigenic variation among Sendai virus strains detected by monoclonal antibodies

Thirteen strains of Sendai virus isolated from various sources in the 1950's and after 1976 were compared for their reactivities with monoclonal antibodies prepared against the prototype strain MN of Sendai virus. Results revealed that while the 5 strains isolated in the 1950's reacted with all the monoclonal antibodies as the prototype strain did, the 2 strains isolated in 1976 and 1978 did not react with an F-specific monoclonal antibody, and the other 6 strains isolated after 1978 lacked reactivity with an HN-specific monoclonal antibody.     

Potential seasonal ecological challenge of heat strain among Australian Aboriginal people practicing traditional subsistence methods: a computer simulation

It has been largely accepted that Australian Aboriginal people practicing hunting and gathering traditionally underused their objective economic possibilities by working short hours relative to nonhunter-gatherer populations. However, the possibility that their subsistence quest might have been limited by potential heat strain has not been considered for Australian hunter-gatherers. In this article the influence of work and heat load on the potential for heat strain among adult male Australian Aboriginal people is modelled. The possibility that the short working day of Arnhem Land adults reported in the literature might reflect ecologically limited work scheduling by way of potential heat strain is examined. Three climatic regions of the North of Western Australia and the Northern Territory were identified, using data available from the Australian Bureau of Meteorology. Data from the months of January, April, July, and October were used with the United States Army Heat Strain Model, along with assumptions with respect to work load and time scheduling. Predictive modelling indicates that a late start to the working day could carry considerable risks of potential heat strain during the summer, when humidity and maximum daily temperature are highest for all three climatic regions, but especially in the tropical coastal region. While extended work times may have been needed to acquire adequate food under traditional conditions, work output could have been limited by potential heat strain under some conditions likely to have prevailed.