The surface pressure was measured as a function of area/molecule for chlorophyll a (Chi) and cytochrome c (Cyt) at a heptane-water interface. At a surface pressure of 6 dyn/cm the area per molecule of C h l(^6) =113 ±6 Ä2, for reduced Cyt c (red. Cyt) the A6 = 5000 ± 300 Ä2 and for oxidized Cyt c (ox. Cyt) /3(6=4100 ± 250 A2. Cyt appears to denature at the interface. Irradiation results in a de...

The relationship between growth rate and food concentration often differs between nauplii and copepodites of the same species, but the nature of these relationships varies between systems and species. The artificial cohort method was used to calculate growth rates of Acartia hudsonica and Eurytemora herdmani nauplii and copepodites in Passamaquoddy Bay, the Bay of Fundy, under a natural range o...

Water deficit (WD) is expected to increase in intensity, frequency and duration in many parts of the world as a consequence of global change, with potential negative effects on plant gas exchange and growth. We review here the parameters that can be derived from measurements made on leaves, in the field, and that can be used to assess the effects of WD on the components of plant photosynthetic ...

Selective harvesting can cause evolutionary responses in populations via shifts in phenotypic characteristics, especially those affecting life history. Brine shrimp (Artemia franciscana) cysts in Great Salt Lake (GSL), Utah, USA are commercially harvested with techniques that select against floating cysts. This selective pressure could cause evolutionary changes over time. Our objectives are to...

Two-band algorithms that use the ratio of reflectances at 672 and 704 nm have already proved successful for chlorophyll a retrieval in a range of coastal and inland waters. An analysis of the effect of reflectance measurement errors on such algorithms is made. It provides important indications of the range of validity of these algorithms and motivates the development of an entirely new type of ...

Empirical relationships between phytoplankton biomass and nutrient concentrations established across a wide range of different ecosystems constitute fundamental quantitative tools for predicting effects of nutrient management plans. Nutrient management plans based on such relationships, mostly established over trends of increasing rather than decreasing nutrient concentrations, assume full reve...

Benthic grazing strongly controls periphyton biomass. The question therefore arises whether benthic grazing could be used as a tool to reduce excessive growth of periphyton in nutrient-enriched rivers. Although benthic invertebrate grazers reduce the growth of periphyton, this is highly context dependent. Here we assessed whether the only obligate herbivorous fish in European rivers, the common...

Eryngium foetidum L. is an important plant cultivated as leafy vegetable and for its essential oil, which is of high economical value in international market. Multiple shoots (17.8) were obtained through direct regeneration from leaf excised from field grown plants of E. foetidum and cultured on Linsmaier and Skoog’s Basal Medium (LSBM) fortified with BAP (1.5 mgl) and PVP (250 mgl). After subc...

The aim of this paper was to verify hydrological and hydrochemical changes in the Iquiparí Lagoon water column, during three months, as related to an artificial sand bar opening. A drastic reduction in water volume occurred 28 hours after the sand bar opening, exposing the bottom sediment. This was densely colonized by submerged aquatic plants, which were dominant in the ecosystem metabolism, s...