Epeiric sedimentation and sea level: synthetic ecostratigraphy

Carbonate strata from the central parts of epicontinental seas are ideal for detailed biostratigraphic study of eustatic sea level change. Using a model for epeiric seas in which carbonate accumulation rate is depth-dependent, we derive synthetic stratigraphies for sea level histories simulating post-glacial transgression and constant and sinusoidally fluctuating ridge volume increase. These sea level histories give distinctively different trends for water depth as a function of stratigraphic position in sections' bathymetric curves. In general, depth is proportional to the rate of sea level rise. Depth-dependent sedimentation leads to a time lag between sea level fluctuation and corresponding depth fluctuation which, as examples show, can approach 10⁶ years for depth fluctuations of only a few meters – a fundamental consideration in reconstructing sea level curves, time-correlating sections by their bathymetric curves, and attempting to relate bathymetric history on continents to mechanisms driving sea level change. Bathymetric curves based on gradient analysis of fossil assemblages (coenocorrelation curves) for Middle Ordovician sections in New York and the American Midwest approximate patterns for sinusoidally increasing sea level. The model's predictions are tested in an ‘artificial experiment’ that takes advantage of differential subsidence between the craton's middle and its edge to make a difference in the bathymetric histories of sections that otherwise record the same sea level history. Depth fluctuations of no more than a few meters over million year spans are potentially useful in time-correlation to within fractions of a cycle's period. The depth-dependence in sedimentation was that, above wave base, net accumulation per year was very roughly three-millionths the water depth. Association of volcanic ash layers with transitory sea level minima on the craton, and with onset of more rapid subduction in the Taconic are - continent collision zone, suggests interrelationship on a million year scale between sea level and large-scale tectonic phenomena.     

Neural mechanisms of auditory information processing by identified interneurones in Orthoptera

Three qualities of sound—the directional, the temporal and the spectral—are important for intraspecific communication in Orthoptera. The neural mechanisms employed by identified interneurones for encoding these sound qualities are illustrated by examples of physiological processes found at different levels of the CNS. Discussed are: (1) the creation of directional information by local interneurones in the thorax, and the use of time-intensity trading in sound location; (2) mechanisms for encoding the temporal parameters of sound by interneurones ascending to the brain; (3) frequency-dependent neural filtering of auditory information by local interneurones.     

Characterization of chlorophyll fluorescence quenching in chloroplasts by fluorescence spectroscopy at 77 K II. ATP-dependent quenching

In intact, uncoupled type B chloroplasts from spinach, added ATP causes a slow light-induced decline ($\text{t}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{≈ 3}\text{min}$) of chlorophyll a fluorescence at room temperature. Fluorescence spectra were recorded after fast cooling to 77 K and normalized with fluorescein as an internal standard. Related to the fluorescence quenching at room temperature, an increase in Photosystem (PS) I fluorescence (F₇₃₅) and a decrease in PS II fluorescence (F₆₉₅) were observed in the low-temperature spectra. The change in the $\text{F}{}_{735}\text{F}{}_{695}$ ratio was abolished by the presence of methyl viologen. Fluorescence induction at 77 K of chloroplasts frozen in the quenched state showed lowered variable (F_v) and initial (F₀) fluorescence at 690 nm and an increase in F₀ at 735 nm. The results are interpreted as indicating an ATP-dependent change of the initial distribution of excitation energy in favor of PS I, which is controlled by the redox state of the electron-transport chain and, according to current theories, is caused by phosphorylation of the light-harvesting complex.     

Isolation of a brain peptide identical to the intestinal PHI (peptide HI)

The isolation of a brain peptide identical to the intestinal peptide PHI (peptide HI) is described. The peptide was isolated from porcine brain extract using a chemical assay method based on its C-terminal isoleucine amide structure. The complete amino acid sequence of the peptide was found to be: His-Ala-Asp-Gly-Val-Phe-Thr-Ser-Asp-Phe-Ser-Arg-Leu-Leu-Gly-Gln-Leu-Ser-Ala- Lys-Lys-Tyr-Leu-Glu-Ser-Leu-Ile-NH2. This sequence is identical to the intestinal peptide thus demonstrating PHI to be a brain-gut peptide. The role of PHI in the central nervous system as a neurotransmitter or neuromodulator is discussed.     

Effects of changes in discharge level on temperature and oxygen regimes in a new reservoir and downstream

Temperature and oxygen regimes were monitored weekly in a four-year old reservoir and downstream for ten weeks during the summer (May 15 to July 30, 1979), and monthly in the fall and winter. During the summer discharge levels were changed from top to bottom in the eighth week, back to top in the ninth, all at 0.71 m³/s (= 25 cfs), and returned to the bottom in the tenth, but at 1.14 m³/s (= 40 cfs). Changing the discharge level had little or no impact on the thermal regime within the lake or downstream at 1.14 m³/s and only a moderate impact on water in the lake near the dam at 0.71 m³/s bottom discharge by generating double thermoclines. Oxygen depletion rates were greatest near the surface of the lake, mainly due to temperature effects, but increased greatly at the 3 m depth, the level of the top discharge port, when discharge was changed from bottom to top. Discharge of anoxic waters through the bottom of the dam caused a drop in oxygen content immediately downstream but oxygen content returned to inflow values within 1 km downstream of the dam.     

Some factors affecting spore replication of Nosema algerae (Microspora,Nosematidae) in Pieris brassicae (Lepidoptera)

The production of Nosema algerae spores was examined in Pieris brassicae. Spore replication in the insect host followed a logistic pattern of development. The factors studied which affected spore production and replication were dose level (5 × 10², 5 × 10³, and 5 × 10⁴ spores per insect), larval instar (fourth and fifth), and cool pretreatment of the insects at 20°C prior to inoculation compared with a constant temperature of 26°C. A three-way analysis showed the interactions between these factors. The logistic pattern of spore replication was used to explain the results.     

Evolutionary explanations of emotions

Emotions can be explained as specialized states, shaped by natural selection, that increase fitness in specific situations. The physiological, psychological, and behavioral characteristics of a specific emotion can be analyzed as possible design features that increase the ability to cope with the threats and opportunities present in the corresponding situation. This approach to understanding the evolutionary functions of emotions is illustrated by the correspondence between (a) the subtypes of fear and the different kinds of threat; (b) the attributes of happiness and sadness and the changes that would be advantageous in propitious and unpropitious situations; and (c) the social emotions and the adaptive challenges of reciprocity relationships. In addition to addressing a core theoretical problem shared by evolutionary and cognitive psychology, explicit formulations of the evolutionary functions of specific emotions are of practical importance for understanding and treating emotional disorders.     

Responses of restored grassland ditch vegetation to hydrological changes, 1989–1992

The impact of hydrological manipulation of an unfertilised, Dutch peat grassland area on plant species composition on ditch banks and in ditchwater was studied. The hydrological manipulation involved raising the groundwater level by admitting nutrient-poor, Ca-rich groundwater in one compartment, and by retaining precipitation in another compartment. A third compartment served as control.The plant species composition showed significant correlations with the following hydrochemical parameters: in bank vegetation with K⁺ concentration, and winter and summer groundwater levels, water depth and elevation; in aquatic vegetation with pH, the concentrations of Cl^- organic-C and NH₄ ⁺ water temperature and elevation.The number of terrestrial plant species increased after compartmentation from 97 to 122; 16 submerged and floating species were found. Most new terrestrial species probably emerged in response to cessation of fertilization and biomass removal, since they showed no preference for any compartment. Five species showed preference for the groundwater compartment and two for the rainwater compartment. Of the new terrestrial plants, seven were relatively rare: Carex panicea, C. oederi, C. pallescens, C. vesicaria, Galium uliginosum, Juncus acutiflorus and Stellaria uliginosa. Of the aquatic plants, eight were relatively rare: Chara globularis, two Callitriche spp., four potamogetonaceae and Ranunculus circinatus.This study indicates that hydrological manipulation of grassland systems in which fertilisation has ceased has profound effects on the vegetation in the ditches of these systems. Bank vegetation responds more slowly and to other hydrochemical factors than aquatic vegetation. Short-term responses in terms of increase in diversity of vegetation pattern and species richness are promising. Long-term responses are not yet known.     

Response by macrozoobenthos biomass to water level regulation in some Finnish lake littoral zones

The relationship of the macrozoobenthos biomass in the littoral area to the yearly fluctuation in water level and the characteristics of the area or lake are studied using data collected from sheltered bays in regulated and natural waters. Most of the lakes were clear and oligotrophic. The benthos biomass at all depths in the littoral decreased with increased water level fluctuation, provided that the transparency of the water was uniform.The macrozoobenthos biomass in the 0–3 m depth zone could be predicted fromlog macrozoobenthos biomass (mg ODW) m^-2=4.25-1.33 (log Biomass Index) in which the Biomass Index is calculated as% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaeOqaiaabM% gacaqGVbGaaeyBaiaabggacaqGZbGaae4CaiaabccacaqGjbGaaeOB% aiaabsgacaqGLbGaaeiEaiaab2dacaqGGaGaaeiiaiaabccacaqGGa% GaaeiiaiaabccacaqGGaGaaeiiaiaabccacaqGGaGaaeiiaiaabcca% caqGGaGaaeiiaiaabccacaqGGaGaaeiiaiaabccacaqGGaGaaeiiai% aabccadaWcaaabaeqabaGaae4DaiaabggacaqG0bGaaeyzaiaabkha% caqGGaGaaeiBaiaabwgacaqG2bGaaeyzaiaabYgacaqGGaGaaeOzai% aabYgacaqG1bGaae4yaiaabshacaqG1bGaaeyyaiaabshacaqGPbGa% ae4Baiaab6gacaqGGaGaaeyAaiaab6gacaqGGaGaaeiDaiaabIgaca% qGLbGaaeiiaiaabchacaqGYbGaaeyzaiaabAhacaqGPbGaae4Baiaa% bwhacaqGZbGaaeiiaiaabMhacaqGLbGaaeyyaiaabkhaaeaacaqGOa% GaaeyBaiaabUdacaqGGaGaae4yaiaabggacaqGSbGaae4yaiaabwha% caqGSbGaaeyyaiaabshacaqGLbGaaeizaiaabccacaqGMbGaaeOCai% aab+gacaqGTbGaaeiiaiaab2gacaqGVbGaaeOBaiaabshacaqGObGa% aeiBaiaabMhacaqGGaGaaeyBaiaabwgacaqGHbGaaeOBaiaabccaca% qG2bGaaeyyaiaabYgacaqG1bGaaeyzaiaabohacaqGPaaaaeaacaqG% tbGaaeyzaiaabogacaqGJbGaaeiAaiaabMgacaqGGaGaaeizaiaabM% gacaqGZbGaae4AaiaabccacaqG2bGaaeyyaiaabYgacaqG1bGaaeyz% aiaabccacaqGPbGaaeOBaiaabccacaqG0bGaaeiAaiaabwgacaqGGa% Gaae4CaiaabggacaqGTbGaaeyzaiaabccacaqGVbGaaeiCaiaabwga% caqGUbGaaeiiaiaabEhacaqGHbGaaeiDaiaabwgacaqGYbGaaeiiai% aabohacaqGLbGaaeyyaiaabohacaqGVbGaaeOBaiaabccacaqGOaGa% aeyBaiaabMcaaaaccaGae8hiaaIaaKiEaiab-bcaGiaaigdacaaIWa% GaaGimaiaac6caaaa!CBD8!\[{\text{Biomass Index = }}\frac{\begin{gathered} {\text{water level fluctuation in the previous year}} \hfill \\ {\text{(m; calculated from monthly mean values)}} \hfill \\ \end{gathered} }{{{\text{Secchi disk value in the same open water season (m)}}}} \user1{x} 100.\]The whole illuminated littoral shifts due to water level fluctuation, which disturbs the zonation of the benthos. Such an increase or decrease in benthic biomass has been observed after one year of disturbance due to water level fluctuation. It need, however, a study based on the carefully planned and collected data, in which it can be taken account by a multivariate statistical analysis also the interactions between the important factors affected the littoral benthos.