The influence of tidal channels on the distribution of salt marsh plant species in Petaluma Marsh,CA, USA

Tidal channels influence the distribution and composition of salt marsh vegetation in a San Francisco Bay salt marsh. Two channel networks in the Petaluma Marsh, Sonoma County, CA, were mapped and characterized using global positioning and geographic information systems. Plant species abundance was sampled on transects placed perpendicular to and extending away from the channel banks. The vegetation showed significant increases in species richness along channel banks and larger areas of effect which increased approximately linearly with channel size. Composition of species assemblages varies with distance from the channel bank and channel size. These results demonstrate that salt marsh plant assemblages, composed of both major and minor species, are distributed with respect to the channel network in Petaluma Marsh.     

Distribution ofMogannia minuta matsumura (Homoptera: Cicadidae) in the Island of Okinawa: Expansion of distribution range during five years

A five-year study on the microgeographical distribution pattern of a sugarcane cicada, Mogannia minuta (=iwasakii), in the Island of Okinawa revealed that the trapezoid type distribution was an unique feature of the distribution of this species. The rate of expansion of the distribution range was remarkably small despite the continuous occurrence of sugarcane plants. These facts can be explained well by the theory of escape. That is, the epidemic cicada populations should be free from predation pressure in the infested area, but those in peripheral zones could be eradicated by predators. The possible role of regulatory factor(s) which suppress further increase in the density in the infested area was suggested.     

Changes of plasma dopamine-beta-hydroxylase activity and other plasma constituents during the cold pressor test

The effect of the cold pressor test on plasma DBH activity in ten healthy human subjects was investigated. Parallel changes of other plasma constituents were ascertained as well. Plasma DBH activity rose by over ten per cent in six of the sen subjects and declined by 14 per cent or more in two subjects; the correlations of altertions in DBH activity with changes of high molecular weight plasma constituents were high (r=0.565 to 0.902); correlations with blood urea nitrogen and plasma glucose were low (r=0.002 to 0.248). The results suggest that factors other than neuronal DBH release may be important in alterations of plasma DBH activity following $\text{acute}$ stresses produced by the cold pressor test in man.     

Biogeographical study of West Siberian hemiboreal forest associations with species range overlay methods

The geographical distributions of plant communities are usually inferred from mapping relevés. Here, we study another approach to map the ranges of associations and higher syntaxa: the joint distribution of the constant species of the associations, i.e. those species most frequently found in the relevés. We ask whether the joint distribution of the species reflects the distribution of the associations and higher syntaxa. Because of limited availability of plant distribution maps we consider species occurring in more than 40% of the relevés of four associations belonging to Western and Central Siberian hemiboreal forests of the class Brachypodio pinnati–Betuletea pendulae. Those species are the most informative for syntaxonomic considerations. The joint distribution is established by overlaying the distribution maps of the species and numerically compared with the mapped distribution of the vegetation communities using Cohen's Kappa. Most species occurring in the associations have a small to mid-sized range. The range size distribution of the contributing species approaches a normal distribution after logarithmic transformation of the range sizes. The geographical extents of the associations are well reflected by the overlays of all constant species. Removing sequentially the species beginning with those having the smallest distribution ranges from the overlay leads to progressive loss of similarity between mapped and modelled range of the associations. For the higher syntaxa (order and class) the similarity between mapped and modelled range increases first but drops at the end of the removal procedure. The less widespread species are particularly important for the recognition of a local plant community, i.e. the association. In contrast, more widespread species allow the definition of the ranges of higher syntaxa and reveal more large-scale geographic relationships of the vegetation. From our quantitative assessment of mapped and modelled maps of the distribution of plant communities, we conclude that the overlay method is useful to infer the geographical extent of plant communities.     

Thermoregulatory activity in the Tecopa pupfish,Cyprindon nevadensis amargosae,an inhabitant of a thermal spring

Synopsis The final thermal preferendum of Tecopa pupfish Cyprinodon nevadensis amargosae collected from a thermal spring was determined in the laboratory in spatial and temporal thermal gradients. Temperatures chosen centred around 30°C — a value close to those reported for other warmwater species in the literature. Upper limits to final preferenda and thermal tolerance in all species of fish are proposed.     

Isolation of a low molecular weight zinc binding ligand from human milk

A low molecular weight zinc binding compound from human milk has been purified by ultrafiltration, gel filtration, and ion-exchange chromatography. Evidence is provided that this compound is citrate. A higher amount of citrate-bound zinc was found in human milk than in cow's milk. It is suggested that the therapeutic value of human milk for patients with the genetic disorder of zinc metabolism acrodermatitis enteropathica (AE) derives from a greater content of bioavailable zinc citrate in human than in cow's milk.     

Eradication of Feral Pigs From Pinnacles National Monument

Abstract: Feral pigs (Sus scrofa) have caused considerable damage where they have been introduced around the world. At Pinnacles National Monument, California, USA, managers were concerned that feral pigs were damaging wetland habitats, reducing oak regeneration, competing with native wildlife, and dispersing nonnative plant species through soil disturbance. To address these threats the National Park Service constructed an exclosure around 57 km² of monument land and through cooperation with the Institute for Wildlife Studies eradicated all feral pigs within the area. Trapping, ground-hunting, hunting dogs, and Judas techniques were used to remove feral pigs. Trapping techniques removed most pigs, but a combination of techniques was required to cause eradication. A series of bait sites and transects across the monument helped focus removal efforts and facilitated detection of the last remaining feral pigs in the exclosure. Consistent funding and cooperation from the National Park Service allowed for a seamless and comprehensive program that provided intensive removal of feral pigs. The successful eradication of feral pigs at Pinnacles National Monument should encourage managers in other areas to implement future control or eradication programs.     

FACTORS CONTROLLING THE INTERTIDAL ZONATION OF IRIDAEA FLACCIDA (RHODOPHYTA)1

Field experiments were used to examine the effects of biological interactions on the abundance of Iridaea flaccida (S. & G.) Silva within and below its normal range in the intertidal zone of central California. A combination of competitor removal, grazer exclusion and transplant manipulations showed that within the I. flaccida zone, this alga can be the first macroscopic plant to become reestablished after clearing and that this can occur in less than two months. Grazing by molluscs within this zone retards, but does not prevent, re-establishment. Although absent prior to the experiments, both I. flaccida and I. cordata (Turn.) Bory settled, grew rapidly and reproduced in cleared areas below the I. flaccida zone, regardless of the presence of grazers. These plants did not establish themselves if entire thalli or holdfasts of other algae normally occupying the lower zone were present. The results support the few other in situ experimental investigations of algal zonation by showing that, when bounded by other plants, the lower limits of intertidal algae are directly determined by competition. They also suggest that I. flaccida and I. cordata may be conspecific.