Seasonal Rise Research Articles

Seasonal circulation around Tasmania: An interface between eastern and western boundary dynamics

The seasonal circulation connecting the Pacific and Indian oceans around Tasmania is documented using seasonal maps from satellite altimetry and sea surface temperature (SST) and in situ mean fields from a high‐resolution climatology of the region (Commonwealth Scientific and Industrial Research Organisation (CSIRO) Atlas of Regional Seas (CARS)). In general, the surface variability displays a very different character off the east and west coasts. Off the east coast the variability is generated externally, being dominated by the western boundary dynamics of the East Australian Current (EAC). In the west it is weaker and arises from the seasonal rise and fall of the coastal sea level, which is due to the seasonal reversing wind patterns. A high‐variability tongue associated with the EAC stretches poleward off the east coast, tracing out a waveguide between the major topographic structures. It has a broad peak in power between 180 and 365 days (>0.08 m), which is a surface height expression of the energetic mesoscale eddy activity associated with the EAC. Distinctive summer and winter patterns of the surface circulation are described which are influenced by the EAC and the Zeehan Current (ZC), respectively. On the east coast in summer (January–March), there is a poleward advection of warm, saline water forced by an episodic coastal boundary flow. The cross‐shelf pressure gradient driving this flow is formed from the difference between the seasonal changes in coastal sea level and the offshore eddies. There is a seasonal reversal of this flow in winter with cool, fresh, modified subantarctic surface waters drawn up from the south. Off the west coast the Zeehan Current operates 180° out of phase with the EAC. It is strongest in winter when it projects warm, relatively saline waters down the western Tasmania coast and around the southern tip of Tasmania. There is a sharp division between the EAC and ZC influence adjacent to the Tasman Peninsula off southeast Tasmania.

OPEC nears production capacity

At first sight, OPEC appears to have a great deal of spare production capacity: over 5 mn bpd in all. On further examination, it is clear that most of this consists either of heavy crude oil for which there is little or no market under present conditions, or of capacity that is shut‐in by violence and civil unrest. OPEC's effective spare production capacity is probably less than 1 mn bpd, which may account for its recent decision not to increase output during the second and third quarters of the year. It also makes it unlikely that OPEC will have much additional oil to offer already tight markets as demand undergoes its normal seasonal rise at the end of the year.

Mathematical model of the development of an epidemic process with aerosol transmission

A model of a pathogenic system with respiratory transmission was proposed. The internal regulation mechanism and the conditions for the onset of seasonal rise in morbidity were studied. The role of asymptomatic carriers in the formation of the virulence potential of the pathogen was shown.

Increases in apoptosis and declines in Bcl-XL protein characterise testicular regression in American crows (Corvus brachyrhynchos)

The present study investigated the cellular changes observed during testicular regression in American crows. Testes from adults caught during the early (March), progressing (April), peak (early May), transitional (late May), and post- (June) breeding season were examined. Apoptosis was assessed by in situ terminal deoxynucleotidyl transferase-mediated dUTP nick end-labelling (TUNEL) and Bcl-X(L) protein immunolabelling. Testis mass increased two-fold from March to early May (P < 0.05), then declined 19-fold by June (P < 0.001) without corresponding changes in body mass (P > 0.05). Testicular activity, evaluated using a spermatogenic index, increased nearly two-fold from March to early May and declined nine-fold in June (P < 0.001). Seminiferous tubule diameter declined four-fold in June compared with earlier months (P < 0.001). In all testes, TUNEL-positive germ cells were detected at low levels, with the highest levels observed in late May (P < 0.001). In contrast, TUNEL-positive Sertoli cells were maintained at low levels in March-April and increased nine-fold in early May (P < 0.001). The Bcl-X(L) immunostaining was detected in Sertoli cells in March-early May; however, staining was most intense in March-April and substantially weaker by early May. These data suggest that the seasonal rise in testicular competence occurs slowly in American crows; however, testis function is terminated rapidly after the breeding season. Furthermore, it is likely that Sertoli cell apoptosis followed by massive germ cell loss is responsible for the rapid reduction in testis mass.

Dynamics of gametogenesis, embryogenesis, and larval release in a Mediterranean homosclerophorid demosponge

We investigated the cycle of sexual reproduction in a Mediterranean population of Corticium candelabrum by light and electron microscopy, using non-destructive tissue sampling. Most individuals of this hermaphroditic species engaged in reproduction. The relationship between seawater temperature and gametogenesis was not straightforward. Oogenesis, characterised by a long phase of oocyte growth, was continuous, with new oocytes appearing every single month of the year. Nevertheless, maximum oocyte production coincided with declining temperatures. Likewise, spermatogenesis started in the coldest month of the year. In contrast, embryonic development and larval release were limited to a few weeks during the seasonal rise of temperature and the warmest months, respectively. Female and male gametes were located in close proximity in the mesohyl. Monociliated spermatogonia putatively derived from choanocytes, and oogonia from archaeocytes. Spermatogenesis, which strongly resembled that in higher animals, produced round spermatozoa that were provided with acrosome and anchoring system for the cilium. Mature oocytes became surrounded by a bacterial layer. Many symbiotic bacteria served for oocyte nourishment, but others were transferred to the larva. As a whole, the reproductive cycle, which also exhibited quite successful fertilisation and low mortality during embryonic development, appears finely tuned to improve the competitive ability of this sponge.

O.208 Effectiveness of bimaxillary advancement for severe obstructive sleep apnea syndrom

In two field trials, the parturition inducing and MMA preventing effects of the prostaglandin F2α analog (PGFA), K 11941∗, were explored. In trial 1, 100 sows were treated with 2 mg and 30 with 3 mg of K 11941 i.m. on day 112 of gestation; 125 sows treated on day 112 with 175 mcg cloprostenol (Planate, ICI) served as positive controls, and 248 sows treated with saline on day 112 of gestation were used as negative controls. Both PGF analogs were equally effective in inducing early parturiton: 84.6% and 83.2% of the sows had farrowed between 20 and 30 hours after treatment. Both treatments reduced stillbirth rate and piglet losses during the first 10 days of life, and lowered the incidence of MMA significantly (6.2 and 5.6% vs 27.3 and 24.2%; p<.001).In a second trial, parturitions were induced in four groups of 60 sows each with 2 mg K 11941, housed in farms with either a chronic high incidence of MMA (A: 45 to 65% or only a seasonal rise in MMA during summer (B: 10 to 50%). Groups were treated either in April/May or August/September; 240 salinetreated, control sows were used. K 11941-induced parturition reduced MMA incidence in farm A during both seasons and prevented the summer rise in farm B (p<.01). Fertility after weaning was impaired in herds with an increased incidence of MMA.

Effect of Ground Water Table on Irrigation Scheduling Model

An irrigation scheduling model was developed based on daily soil water balance which takes into account the effect of water table on irrigation water requirement for wheat crop at Mosul area for eleven years. Capillary rise of water table was estimated with Darcy’s equation .Crop evapotranspiration was estimated by pan evaporation method. The model inputs are daily climatological data for eleven years at Mosul Station, soil data (total available water, field capacity, permanent wilting point, allowable percent depletion, saturated hydraulic conductivity),and crop data(root depth for wheat crop, crop coefficient).The model estimates daily and seasonal actual evapotranspiration, effective rainfall, irrigation requirement and upward capillary rise from water table. Using the model for wheat, the seasonal irrigation requirements were reduced by 40% for silt loam soil and 90% for loam soil ,avoiding crop water stress or excessive irrigation.

EFFECT OF GROUND WATERTABLE ONIRRIGATION SCHEDULING MODEL

An irrigation scheduling model was developed based on daily soil water balance which takes into account the effect of water table on irrigation water requirement for wheat crop at Mosul area for eleven years. Capillary rise of water table was estimated with Darcy's equation .Crop evapotranspiration was estimated by pan evaporation method. The model inputs are daily climatological data for eleven years at Mosul Station, soil data (total available water, field capacity, permanent wilting point, allowable percent depletion, saturated hydraulic conductivity),and crop data(root depth for wheat crop, crop coefficient).The model estimates daily and seasonal actual evapotranspiration, effective rainfall, irrigation requirement and upward capillary rise from water table. Using the model for wheat, the seasonal irrigation requirements were reduced by 40% for silt loam soil and 90% for loam soil ,avoiding crop water stress or excessive irrigation.

GUT CONTENT, PHYTOPLANKTON ABUNDANCE AND REPRODUCTIVE SEASON IN THE BLACK OYSTER (HYOTISSA HYOTIS, LINNE, 1758) AT ISLA ESPIRITU SANTO, GULF OF CALIFORNIA

Hyotissa hyotis specimens were collected at Espíritu Santo Island, Gulf of California, from March 1998 to March 1999. Water temperature was recorded, gut-content samples were obtained, phytoplankton abundance was estimated, and the reproductive status was inferred through the gonadic index. Gut content included phytoplankton, mostly diatoms (86.5%) and dinoflagellates (13.5%). The highest phytoplankton frequency in gut contents occurred from March to May, along with a growing phytoplankton abundance in seawater, matching the period of gonad development and the seasonal rise in temperature. Phytoplankton comprised diatoms (73.3%), dinoflagellates (10.4%), nannoplankton (18.8%), cyanobacteria (3.3%), and silicoflagellates (2.2%). The gonadic index suggests that this population has an annual reproductive pattern. Gonad development takes place from March to April, with the population ripening between April and July, matching the seasonal temperature rise from 22 °C to 27 °C, and spawning from July to September when temperatures reach a peak between 27 °C to 29 °C. From October onwards the population enters a postspawning and reproductive-inactivity phase.

High rates of geomorphological processes in a tropical area: the Remparts River case study (Réunion Island, Indian Ocean)

Reunion Island is characterized by rapid landscape evolution resulting from its cyclonic tropical climate. However, local active surface processes are not well understood. The relationships between climatic events, large scale landslides and torrential transport of sediment by the rivers remain unclear. The Remparts River is an appropriate area for studying such geomorphological processes, as it deeply incises the active Piton de la Fournaise volcano. In this study, different approaches are used to analyze the morphological evolution of the river from the sediment production areas to the outlet over the last 40 years. Recurrent events of huge mass wasting occur at Mahavel Cliff, upstream of one of the river tributaries, the most recent producing around 50×10 6 m 3 of sediment in 1965. Combined analyses of the sequence of cyclonic events, major mass wasting events and aerial photography interpretation over the last 40 years led to the proposal of a functional model of river system responses to these events. The river system can be divided into three compartments, each affected by three classes of geomorphological events. The sedimentary response (erosion and/or aggradation) of each compartment to a triggering event, such as cyclonic rainfall and/or seasonal rise of water discharge, is controlled both by the magnitude of the climatic event and by the state of the compartment resulting from previous evolution. A set of five aerial photographs and a satellite image showing the evolution of the studied area during the last 40 years are examined in detail in the light of the functional model. Observations confirm a rapid and complex evolution of the river bed (erosion and aggradation), and provide information about the dynamics of the sediment transfer from the production areas to the ocean. Analysis of two distinct topographic datasets bracketing the last major cyclone Dina in 2002 allows the estimation of the river sediment budget resulting from this event. The net volume of aggraded sediments in the river bed is estimated at around 8×10 6 m 3. With no major collapse event recorded at Mahavel Cliff, sediment transfer due to the flood associated with the 3-day cyclone Dina event is responsible for this significant increase in river bed sediment volume. This quantification shows that several million cubic meters of sediment may take only a few years to spread over more than 5 km downstream. The river bed has now reached its highest elevation since the 1965 landslide, with potential consequences for natural hazards in the area of the outlet at the city of Saint-Joseph.

Factors affecting seasonal mortality of rosy bitterling (Rhodeus ocellatus kurumeus) embryos on the gills of their host mussel

AbstractI investigated the seasonal change in factors affecting embryonic mortality in the rosy bitterling, Rhodeus ocellatus kurumeus, a freshwater fish that spawns on the gills of living unionid mussels. Research was conducted in a small pond during 1999 and 2001 in which bitterling were provided with Anodonta sp. mussels for spawning. Bitterling spawned between April and July, peaking mid–late May. Seasonal survival rate of bitterling embryos in their mussel hosts was unimodal, with a peak between late April and mid May (about 70% of total spawnings). In mid April, survival was about 50%. The lowest survival was from late May to July (0%). Losses of bitterling embryos from mussels were identified by ejections from the mussel host. Ejections were categorized as either ejections of live embryos, or ejections of embryos that died in the mussel and were subsequently expelled from the mussel. Ejection rates of live embryos were higher in the earlier part of the spawning period (early–mid April) and dead embryo ejections in the later period (after June). The ejection rate of live embryos was higher among younger embryos earlier in the season, probably because of the incomplete development of morphological and behavioural traits associated with maintaining the embryo inside the mussel gill chambers, and as a consequence of a more protracted developmental period at low temperatures making them more susceptible to ejection. The ejection rate of dead embryos was higher in older embryos later in the season, and in larger mussels and at high embryo densities. The survival of embryos in mussels was probably related to oxygen availability, with mortalities probably caused by asphyxiation. Increased embryo mortalities may arise through competition among embryos, between embryos and mussel, and ambient dissolved oxygen levels. The optimal period for bitterling to spawn may represent a balance between two opposing factors; with positive and negative effects of a seasonal rise in temperature directly affecting embryonic growth rate and oxygen availability.

The seasonality of human campylobacter infection and Campylobacter isolates from fresh, retail chicken in Wales

Seasonal peaks in both human campylobacter infections and poultry isolates have been observed in several European countries but remain unexplained. We compared weekly data on human campylobacter infections with thermophilic Campylobacter isolation rates from fresh, retail chicken samples (n = 514) purchased weekly in Wales between January and December 2002. Human isolates (n = 2631) peaked between weeks 22 and 25 (early June) and chicken isolates (n = 364) between weeks 24 and 26 (late June). In the absence of a temporal association, we postulate that the seasonal rise in humans is not caused by a rise in isolation rates in poultry but that both are more likely to be associated with a common, but as yet unidentified, environmental source.

Testosterone and group size in cliff swallows: testing the “challenge hypothesis” in a colonial bird

The “challenge hypothesis” states that increases in testosterone levels of male animals during the breeding season are directly related to the extent of intrasexual competition for resources or mates that they experience. Although often tested in territorial species, the challenge hypothesis has not been evaluated for colonial animals that live in groups of different sizes and that thus experience different intensities of intrasexual competition. We measured circulating testosterone levels of male and female cliff swallows ( Petrochelidon pyrrhonota) in southwestern Nebraska, where these birds nest in colonies of widely different sizes. Males had significantly higher testosterone levels than females, as expected. For males especially, there was a seasonal rise in testosterone levels early in the nesting cycle, corresponding to the period when birds were establishing nest ownership and egg laying, and then a fall as they switched to parental duties. Testosterone levels varied significantly with colony size; for both sexes, birds in larger colonies had higher levels of testosterone than those in smaller colonies when controlling for date. Age and body mass were not related to testosterone levels. Higher levels of testosterone for birds of both sexes in larger colonies probably reflect greater competition for matings, often extra pair, in the more social nesting situations. The results support the predictions of the challenge hypothesis.

Trends in the Lake Superior Water Budget Since 1948: A Weakening Seasonal Cycle

An analysis of Lake Superior water levels from 1948–1999 reveals that the seasonal cycle has decreased in amplitude by 20% (from 40 cm to 32 cm). This change is manifested as a downward trend in summer and autumn lake levels (when levels are typically highest) accompanied by roughly no change in winter and spring lake levels (and an overall 4-cm drop in annual mean levels). The decreased rates of seasonal rise and fall in lake level over the 51-year interval reflect a large decrease in the net monthly influx of water during the late spring (up to –1,360 m 3/s) coupled with a nearly compensating increase in net influx during late autumn (up to +1,100 m 3/s). Analysis of the Lake Superior water budget indicates that these changes are primarily the result of trends in runoff and over-lake precipitation. A systematic decrease in outflow through the St. Marys River is also evident during July-December (in association with the lower lake levels), as well as a moderate shift in the seasonal pattern of lake evaporation (but not the annual mean). The observed water budget trends are primarily related to variations in climate, rather than lake regulation. Land surface effects are also important, as suggested by a 20% increase in annual mean evapotranspiration during the 51-year interval and large changes in monthly storage (e.g., snowmelt, groundwater, etc.). Significant uncertainties are present in the calculated water budget, and it is suggested that a likely source of error is in measured precipitation and (especially) runoff.

Niche partitioning and photosynthetic response of alectorioid lichens from subalpine spruce–fir forest in north-central British Columbia, Canada: the role of canopy microclimate gradients

The distribution of alectorioid lichens in subalpine spruce–fir forests of north-central British Columbia is strongly influenced by vertical position within the canopy; Bryoria dominates upper canopy exposures, while Alectoria dominates lower canopy positions. The hypothesis that this height-related niche partitioning reflects differential growth responses to gradients in canopy microclimate is examined. Field measurements of canopy microclimate, taken over a 2-year period, were used in conjunction with laboratory-based measurements of net photosynthesis (NP) and dark respiration to model net assimilation (NA) response of Alectoria sarmentosa and Bryoria spp. (mixed collections of Bryoria fremontii and B. pseudofuscescens) at two different heights (15 and 4 m) within the canopy. Microclimate measurements indicate that lichen thalli are regularly hydrated from snowmelt events during the winter period (October–April), totalling 26 and 29% of the time, respectively, for Alectoria and Bryoria, though most winter hydration exposure ( c. 75%) occurred in the dark. In the summer (May–September), rainfall was the major hydration source, with Alectoria and Bryoria each hydrated c. 16% of the time (45% of this in the dark). The NP temperature optimum ( T opt) in light saturated thalli of Alectoria was 18·1 and 22·9°C, for winter and summer measurements, respectively. In Bryoria the corresponding seasonal rise in T optwas smaller, from 15·9 to 16·3°C. Both species showed an increase in maximum rates of NP during the summer period, from 1·52 to 1·92 mg CO 2 g −1 h −1for Alectoria, and from 1·79 to 2·33 mg CO 2 g −1 h −1for Bryoria. Although lichen hydration events peaked in early winter (October and November), NA modelling predicts that maximum growth should occur during the summer period. In Alectoria, higher rates of NA were predicted for thalli in lower canopy positions, especially during the summer months. In Bryoria, no clear trends of NA uptake with canopy position were observed. Thus, while NP response to gradients of canopy microclimate may provide a basis for niche partitioning in Alectoria, other factors (perhaps exclusionary) may be more important for Bryoria. One such factor is documented, namely the greater sensitivity of Bryoria to extended hydration exposure and we speculate that greater rates of fragmentation in upper canopy exposures may limit upper canopy biomass accumulation in Alectoria. Niche partitioning in these alectorioid lichens may therefore reflect both positive (growth responses) and negative (physical and physiological limitations) responses to gradients in canopy microclimate.

Different methods of local allergen-specific immunotherapy.

In the treatment of allergic disorders, specific immunotherapy (SIT) occupies a central role as the only currently available causal method of treatment. The concept of ‘‘local immunotherapy’’ includes all nonsubcutaneous forms of SIT, which are used to treat allergic disorders such as rhinitis and asthma. Nasal, bronchial, oral and sublingual administration of allergen extracts is regarded as local immunotherapy (LIT). Attempts were made very early to produce tolerance to certain allergens by the oral route. Dakin reported in1829 that North American Indians regularly chewed small amounts of leaves of the ‘‘poison ivy’’ (Rhus toxicodendron) in order to prevent or weaken the severe dermatitides that occur after contact with this plant (Dakin, 1829 quoted after (1)). In 1900, 11 years before the first work on subcutaneous immunotherapy, Curtis published an article about the efficacy of oral allergen-specific immunotherapy (OIT) in hay fever (2). This was followed five years later by other reports about the success of OIT in cow’s milk allergy (3). In the 1920s and 1930s, too, reports of positive experiences with this method appeared again and again. However, a negative, multicentre comparative study of ragweed pollinosis (4) (in which, interestingly, good results were reported in children!) severely limited the use of OIT in adults in the Anglo-Saxon countries. In the early 1950s, Schuppli in Basel, Switzerland took up OIT again. His positive results in children ensured that this method soon became widespread (5–12). New methods of local application were sought, because various studies in recent years showed that OIT is clearly inferior to allergen-specific subcutaneous (injected) immunotherapy (SIT) with regard to both clinical and immunological efficacy. From a clinical aspect however, there is a whole series of arguments to explain the preference for LIT compared to injected IT. Poor compliance can limit the applicability of injected SIT (13). Because LIT can be carried out at home by the patient and the injections in the doctor’s office are no longer necessary, greater compliance is ascribed to LIT than to SIT. However, more precise studies of this subject are lacking, so the effective compliance of LIT patients is not known. Severe systemic side-effects restrict the broad use of SIT, although the risk in hay fever patients is lower compared to asthma patients (14, 15). When SIT is carried out correctly, severe systemic side-effects in patients with allergic rhinitis, who are treated with potent extracts, occur in about 5% of all the SIT injections (16). Based on the published data, on the other hand, systemic side-effects appear to occur only very rarely with LIT. The rapid development of molecular biology and progress not only in general allergen characterization but also in the production of large quantities of recombinant allergens have reawakened interest in recent years in local immunotherapy (LIT), both in science and among the producers of allergen extracts. At present there appears to be a trend away from oral towards sublingual allergen-specific IT (SLIT).

Rainfall‐runoff modelling of a humid tropical catchment: the TOPMODEL approach

AbstractTOPMODEL, a semi‐distributed, topographically based hydrological model, was applied to simulate continuously the runoff hydrograph of a medium‐sized (379 km2), humid tropical catchment. The objectives were to relate hydrological responses to runoff generation mechanisms operating in the catchment and to estimate the uncertainty associated with runoff prediction. Field observations indicated that water tables were not parallel to the surface topography, particularly at the start of the wet season. A reference topographic index λREF was therefore introduced into the TOPMODEL structure to increase the weighting of local storage deficits in upland areas. The model adaptation had the effect of deepening water tables with distance from the river channel. The generalized likelihood uncertainty estimation (GLUE) framework was used to assess the performance of the model with randomly selected parameter sets, and to set simulation confidence limits. The model simulated well the fast subsurface and overland flow events superimposed on the seasonal rise and fall of the baseflow. The top ranked parameter sets achieved modelling efficiencies of 0·943 and 0·849 in 1994 and 1995 respectively. The GLUE analysis showed that the exponential decay parameter m, controlling the baseflow and the local storage deficit, was the most sensitive parameter. There was increased uncertainty in the simulations of storm events during the early and late phases of the season, which was due to a combination of: errors in detecting the rainfall depths for convectional rainfall events; the treatment of rainfall as a catchment areal value; and, the strong seasonality in runoff response in the humid tropics. Copyright © 2002 John Wiley &amp; Sons, Ltd.

The rôles of photoperiod and nutrition in the seasonal increases in growth and insulin-like growth factor-1 secretion in male red deer

AbstractYoung male red deer follow a seasonal growth pattern that can be shifted by altering the photoperiod they experience. An increase in photoperiod to 16 h of light per day (16L : 8D) during winter advances the onset of rapid growth and high food intake that normally commences in spring. These changes are associated with increased growth hormone (GH) and insulin-like growth factor-1 (IGF-1) secretion. The GH/IGF-1 axis is acutely sensitive to the level of nutrition and the relative rôles of photoperiod and nutrition in determining the spring IGF-1 rise is unknown. The present experiment set out to examine this by exposing two groups of deer (no. = 8 per group) to a photoperiod shift during their 1st year of life (16L : 8D from 2 June), designed to cause accelerated growth and increased food intake after approximately 7 weeks. However, after 6 weeks the food intake (pellets containing 11 MJ metabolizable energy and 160 g crude protein per kg dry matter (DM)) of one group (LDRES) was clamped, thereby preventing the intake component of the response. The intake of the other group (LDAL) remained ad libitum for a further 12 weeks until 6 October, when the experiment concluded.During the first 6 weeks of 16L : 8D, growth rate (118 (s.e. 15·4) g/day) and food intake (1·37 (s.e. 0·031) kg DM per head per day) did not differ between the groups. Food intake following the clamp in LDRES averaged 1·40 (s.e. 0·015) kg per head per day. The intake of LDAL increased 2 weeks after the clamp and thereafter was higher than LDRES (P &lt; 0·001). Food intake of LDAL averaged 2·13 (s.e. 0·051) kg during the nutritional clamp period. Growth rates increased in both groups during the first 3 weeks of the clamp, averaging 237 (s.e. 25·0) g/day, then growth slowed in LDRES and live weights diverged. Growth rates until the end of the experiment (147 (s.e.23·0) g/ day v. 299 (s.e. 12·5) g/day, P &lt; 0·001) and mean live weight over the last 5 weeks of the experiment were lower (P &lt; 0·05) in LDRES than LDAL, weights reaching 88·3 (s.e. 1·86) kg and 97·9 (s.e. 2·74) kg respectively on the final sampling date. Metatarsal bone length grew more in LDAL than in LDRES (3·1 v. 2·2 cm, s.e.d. = 0·23, P &lt; 0·01). Prior to the nutritional clamp, mean plasma prolactin and IGF-1 concentrations increased at 3 and 6 weeks after 16L : 8D respectively, in both groups. Prolactin concentrations were lower in LDRES than LDAL on two occasions, at weeks 3 and 7 after the onset of the nutritional clamp, and IGF-1 concentrations were lower in LDRES than LDAL (676 v. 872 ng/ml, s.e.d. = 73·8, P &lt; 0·05) over the last 7 weeks of sampling.In summary, a photoperiodically driven increase in IGF-1 occurred even when the usual associated increase in food intake was prevented. This indicates that the seasonal IGF-1 rise in red deer is not a consequence of the increased food intake, although the latter appears necessary to maintain elevated IGF-1 concentrations. The rise in IGF-1 may therefore be considered as a component of the photoperiodically entrained seasonal drive to grow, and the increase in food intake a response to satisfy the increased energy demand.

Seasonal-scale Transport Patterns in a Multi-inlet Coastal Lagoon

A finite-difference numerical model is used to investigate seasonal-scale lagoon-shelf exchanges and transport within Indian River, a multi-inlet lagoon on the Atlantic coast of Florida, U.S.A. Meteorological, hydrologic and hydrographic data quantify forcing by seasonally-varying wind stress, coastal sea level and the net freshwater gain. The along-axis component of the wind stress reverses seasonally. North-westward wind stress stores water in the northern part of the lagoon in summer months, then south-westward wind stress removes it in winter months. The seasonal rise and fall in water level at opposite ends of the lagoon differ by ±0·1–0·2m, primarily as a result of seasonal variations in wind forcing. The rise and fall of coastal sea level forces water into the lagoon during summer months, then draws it out during late fall and winter months. Net freshwater gain forces water out of the inlets during summer months, when rainfall rates are highest, and to a lesser extent during mid winter, when evaporation is relatively low. When forcing is by shelf tides only, simulations suggest that the northern and southern inlets are flood-dominant, while the central inlet is ebb dominant. With the addition of seasonal-scale forcing, the northern inlet becomes flood-dominant from late fall through early spring, then ebb-dominant during the rest of the year. The central and southern inlets are ebb-dominant throughout the year but seasonal variations differ. The central inlet has strongest outflow during summer months, while the southern inlet has strongest outflow during fall and winter months. Convergent and divergent patterns of transport within the lagoon are a complex response to both local and remote forcing. Simulations suggest that transport in the dredged part of a navigation channel opposes transport outside the channel.

Consequences of future climate change and changing climate variability on maize yields in the midwestern United States

Any change in climate will have implications for climate-sensitive systems such as agriculture, forestry, and some other natural resources. With respect to agriculture, changes in solar radiation, temperature, and precipitation will produce changes in crop yields, crop mix, cropping systems, scheduling of field operations, grain moisture content at harvest, and hence, on the economics of agriculture including changes in farm profitability. Such issues are addressed for 10 representative agricultural areas across the midwestern Great Lakes region, a five-state area including Indiana, Illinois, Ohio, Michigan, and Wisconsin. This region is one of the most productive and important agricultural regions in the world, with over 61% of the land use devoted to agriculture. Individual crop growth processes are affected differently by climate change. A seasonal rise in temperature will increase the developmental rate of the crop, resulting in an earlier harvest. Heat stress may result in negative effects on crop production. Conversely, increased rainfall in drier areas may allow the photosynthetic rate of the crop to increase, resulting in higher yields. Properly validated crop simulation models can be used to combine the environmental effects on crop physiological processes and to evaluate the consequences of such influences. With existing hybrids, an overall pattern of decreasing crop production under scenarios of climate change was found, due primarily to intense heat during the main growth period. However, the results changed with the hybrid of maize ( Zea mays L.) being grown and the specific location in the study region. In general, crops grown in sites in northern states had increased yields under climate change, with those grown in sites in the southern states of the region having decreased yields under climate change. Yields from long-season maize increased significantly in the northern part of the study region under future climate change. Across the study region, long-season maize performed most successfully under future climate scenarios compared to current yields, followed by medium-season and then short-season varieties. This analysis highlights the spatial variability of crop responses to changed environmental conditions. In addition, scenarios of increased climate variability produced diverse yields on a year-to-year basis and had increased risk of a low yield. Results indicate that potential future adaptations to climate change for maize yields would require either increased tolerance of maximum summer temperatures in existing maize varieties or a change in the maize varieties grown.