Coccolithophores: a major phytoplankton component in mature upwelled waters off the Cape Peninsula,South Africa in March, 1983

Coccolithophores, together with other phytoplankton, were sampled at ten stations along a transect following the general orientation of the Cape Peninsula upwelling plume in March, 1983. Thirteen coccolithophore species were identified with Emiliania huxleyi dominating the assemblages. Coccolithophores and other microflagellates were more abundant than diatoms along the transect except at one station in mature upwelled water. Very high populations (2 340×10³ cells l^-1) of coccolithophores were found in mature upwelled water adjacent to the oceanic front. This count is one of the highest counts ever recorded in an upwelling area. The anomalous warm event prior to sampling may have had a residual effect on seeding, contributing towards the predominance of small-celled phytoplankton over chain-forming diatoms.     

The Role of Ground Water in Generating Streamflow in Headwater Areas and in Maintaining Base Flow1

Abstract: The volume and sustainability of streamflow from headwaters to downstream reaches commonly depend on contributions from ground water. Streams that begin in extensive aquifers generally have a stable point of origin and substantial discharge in their headwaters. In contrast, streams that begin as discharge from rocks or sediments having low permeability have a point of origin that moves up and down the channel seasonally, have small incipient discharge, and commonly go dry. Nearly all streams need to have some contribution from ground water in order to provide reliable habitat for aquatic organisms. Natural processes and human activities can have a substantial effect on the flow of streams between their headwaters and downstream reaches. Streams lose water to ground water when and where their head is higher than the contiguous water table. Although very common in arid regions, loss of stream water to ground water also is relatively common in humid regions. Evaporation, as well as transpiration from riparian vegetation, causing ground‐water levels to decline also can cause loss of stream water. Human withdrawal of ground water commonly causes streamflow to decline, and in some regions has caused streams to cease flowing.     

Evaluation of Land Condition Trend Analysis for Birds on a Kansas Military Training Site

/ Land condition trend analysis (LCTA) is a long-term monitoring program used on military training lands to identify ecological changes that result from training and management activities. We initiated LCTA at the Kansas Army National Guard Training Facility (KANGTF) in Saline County, Kansas, in March 1998. This paper evaluates the LCTA methodology for birds by comparing LCTA results with a modified methodology designed to place sampling transects in field-identified rather than satellite-identified land-cover types. In the satellite-identified land-cover types developed at the site, grassland habitats included a large component of woody vegetation, which resulted in poor resolution of bird assemblages associated with the different land-cover types. Using these cover classes, mixed grass prairie included five grass/forb (g/f) and 10 woody-dependent species; old-field included four g/f and four woody-dependent species; and riparian included one g/f and six woody-dependent species. LCTA sampling was too limited in the ecologically important riparian woodland habitat with the result that bird species were not adequately sampled there. In the alternate sampling strategy, we identified three land-cover classes (grassland, hedgerow, and riparian woodland) by field reconnaissance and increased sampling in the riparian woodland. Grassland included six g/f and three woody-dependent species; hedgerow included six g/f and 20 woody-dependent species, and riparian included two g/f and 19 woody-dependent species. The modifications greatly improved the resolution of bird assemblages associated with land-cover classes at the KANGTF. Use of the alternative sampling method should improve the ability to detect long-term trends in the bird communities.     

Djungarian hamsters (Phodopus sungorus) are not susceptible to stimulating effects of 6-methoxy-2-benzoxazolinone on reproductive organs

The secondary plant metabolite 6-methoxy-2-benzoxazolinone (6-MBOA) is abundant in vegetative parts of monocotyledons emerging in spring. This grazing protective has been shown to promote gonadal growth and, thus enable precise alignment of reproductive activity with favorable environmental conditions in a variety of seasonally breeding rodent species. Feeding and breeding ecology make the Djungarian hamster (Phodopus sungorus) a potential candidate using 6-MBOA as an acute environmental cue to optimize reproductive timing when photorefractoriness induces reproductive recrudescence. Therefore, four different experiments were designed to examine whether the hamsters’ reproductive organs are responsive to oral 6-MBOA administration under different photoperiodic conditions. Only under a long photoperiod, we found a slight increase in uterine weights. In a short photoperiod, 6-MBOA-treated hamsters showed a slight body weight gain without a change in uterine weights. However, these marginal effects are likely not to be of ecophysiological significance for reproductive timing. The results are in agreement with the common view that the annual changes in photoperiod length are not only the predominant environmental cue for Djungarian hamsters, but are also sufficient to synchronize reproductive efforts with favorable breeding conditions in highly predictable climates like the continental Asian steppes.     

Hibernation in Malagasy mouse lemurs as a strategy to counter environmental challenge

The spiny forest of southwestern Madagascar is the driest and most unpredictable region of the island. It is characterized by a pronounced seasonality with high fluctuations in ambient temperature, low availability of food, and a lack of water during the cool dry season and, additionally, by changes in environmental conditions between years. One of the few mammalian species that manages to inhabit this challenging habitat is the reddish-gray mouse lemur (Microcebus griseorufus). The aim of our study was to determine whether this small primate uses continuous hibernation as an energy saving strategy, and if so, to characterize its physiological properties. We measured skin temperature of 16 free-ranging individuals continuously over 3 months during the cool dry season using collar temperature data loggers. Prolonged hibernation was found in three mouse lemurs and was not sex dependent (one male, two females). Skin temperature of hibernating individuals tracked ambient temperature passively with a minimum skin temperature of 6.5°C and fluctuated strongly each day (up to 20°C), depending on the insulation capacity of the hibernacula. Individuals remained in continuous hibernation even at an ambient temperature of 37°C. The animals hibernated continuously during the dry season, and hibernation bouts were only interrupted by short spontaneous arousals. The study emphasizes that hibernation is an important measure to counter environmental challenge for more tropical species than previously thought, including primates. It furthermore provides evidence that tropical hibernation is functionally similar among tropical species.     

Competitive kinetics of adsorption onto activated carbon for emerging contaminants with contrasting physicochemical properties

Environmental Science and Pollution Research - Activated carbon (AC) can be used for the removal of emerging contaminants (e.g., drugs) in water and wastewater treatment plants. In the present...     

Using experimental reintroductions to resolve the roles of habitat quality and metapopulation dynamics on patch occupancy in fragmented landscapes

Declines of species in fragmented landscapes can potentially be reversed either by restoring connectivity or restoring local habitat quality. Models fitted to snapshot occupancy data can be used to predict the effectiveness of these actions. However, such inferences can be misleading if the reliability of the habitat and landscape metrics used is unknown. The only way to unambiguously resolve the roles of habitat quality and metapopulation dynamics is to conduct experimental reintroductions to unoccupied patches so that habitat quality can be measured directly from data on vital rates. We, therefore, conducted a 15-year study that involved reintroducing a threatened New Zealand bird to unoccupied forest fragments to obtain reliable data on their habitat quality and reassess initial inferences made by modeling occupancy against habitat and landscape metrics. Although reproductive rates were similar among fragments, subtle differences in adult survival rates resulted in λ (finite rate of increase) estimations of <0.9 for 9 of the 12 fragments that were previously unoccupied. This was the case for only 1 of 14 naturally occupied fragments. This variation in λ largely explained the original occupancy pattern, reversing our original conclusion from occupancy modeling that this occupancy pattern was isolation driven and suggesting that it would be detrimental to increase connectivity without improving local habitat quality. These results illustrate that inferences from snapshot occupancy should be treated with caution and subjected to testing through experimental reintroductions in selected model systems.