Inter-seasonal Changes Research Articles

Оценка влияния старовозрастных ельников на углеродный баланс таежных лесов Валдая

Monitoring the photosynthesis- and respiration-related characteristics of the old-aged forests of the Valday Region is of paramount importance since it is imperative that the role of all factors contributing to their carbon balance should be evaluated. This work presents data on seasonal dynamics of midday carbon-dioxide exchange and photosynthetic productivity of the Norway spruce (Picea abies L.) in May - October 2018-2020. It was established that the main factors determining the CO2 assimilation rate of the spruce are the air temperature and illumination. The average annual photosynthesis intensity level was more than two times higher than the light-dependent respiration level. Significant interseasonal changes in spruce photosynthetic productivity were revealed: the maximum and minimum photosynthetic productivity was detected in June-July and October, respectively. The interannual changes were related to the weather conditions and to the state of the forest stand in the tested area. The total carbon dioxide uptake by spruce needles in 2018, 2019, and 2020 was 3.3, 2.13, and 1.15 ton of CO2∙ha-1∙year-1. The average value of net primary production (0.37 ton of C∙ha-1∙year-1) and the positive carbon dioxide balance of the Norway spruce testify to a considerable influence of old-aged spruce forests on the carbon balance of the forest cenoses of the Valday Region.

Variations and Interseasonal Changes in the Gut Microbial Communities of Seven Wild Fish Species in a Natural Lake with Limited Water Exchange during the Closed Fishing Season.

The gut microbiota of fish is crucial for their growth, development, nutrient uptake, physiological balance, and disease resistance. Yet our knowledge of these microbial communities in wild fish populations in their natural ecosystems is insufficient. This study systematically examined the gut microbial communities of seven wild fish species in Chaohu Lake, a fishing-restricted area with minimal water turnover, across four seasons. We found significant variations in gut microbial community structures among species. Additionally, we observed significant seasonal and regional variations in the gut microbial communities. The Chaohu Lake fish gut microbial communities were predominantly composed of the phyla Firmicutes, Proteobacteria(Gamma), Proteobacteria(Alpha), Actinobacteriota, and Cyanobacteria. At the genus level, Aeromonas, Cetobacterium, Clostridium sensu stricto 1, Romboutsia, and Pseudomonas emerged as the most prevalent. A co-occurrence network analysis revealed that C. auratus, C. carpio, and C. brachygnathus possessed more complex and robust gut microbial networks than H. molitrix, C. alburnus, C. ectenes taihuensis, and A. nobilis. Certain microbial groups, such as Clostridium sensu stricto 1, Romboutsia, and Pseudomonas, were both dominant and keystone in the fish gut microbial network. Our study offers a new approach for studying the wild fish gut microbiota in natural, controlled environments. It offers an in-depth understanding of gut microbial communities in wild fish living in stable, limited water exchange natural environments.

Vostok Bay: interseasonal changes in hydrological, hydrochemical and microbiological properties

Current ecological state of the Vostok Bay (Peter the Great Bay, Japan Sea) in spring, summer, and autumn seasons is described on the data of CTD profiling, chemical analysis of the water sampled at the sea surface and bottom, and microbial indication of the surface water. Strong seasonal variations are revealed for all examined parameters, driven by monsoon cycle. The winter monsoon in autumn with northwestern wind predominance causes the river runoff weakening and off-shore surge with the water removal from the top of the bay and the compensating inflow along the eastern coast distinguished by heightened values of salinity and dissolved oxygen and low values of biochemical oxygen demand (BOD5 < 1 mg/L). The summer monsoon in spring and summer with southeastern winds increases the river runoff and simultaneously the inflow of fresh water from the open sea, so causes a sharp difference in the water properties between parts of the Vostok Bay. Bioproductivity increases in these seasons that is reflected in increasing of BOD5 (up to 2 mg/L and sometimes more) and organic phosphorus concentration (up to 50 μg/L and more). In July, when the river runoff is blocked in the northwestern sector of the bay by onshore surge, the maximum number of bacteria is recorded there (up to 105 CFU/mL), including Escherichia coli group at all coastal stations in concentrations of 10–100 CFU/mL, which are not observed in the central and open parts of the bay. Among the groups of metal-resistant microorganisms, relative abundance of nickel-resistant bacteria is noted (up to 103 CFU/mL) that is a sign of hydrocarbon fuels combustion. The hydrocarbon pollution is confirmed by ubiquitous distribution of oil-oxidizing and diesel-resistant microorganisms detected mostly (up to 2.8 ∙ 104 CFU/mL in summer) in the northern part of the bay. Generally, the internal northern part of the bay is distinguished by high abundance of microorganisms belonged to different ecological and trophic groups, because of mutual impacts of the rivers, the coastal highway, nearby settlements, and sandy beaches occupied by vacationers in summer.

Seasonal changes in the profile of blood plasma fatty acids as a mechanism of human adaptation to the extreme conditions of the North

Extreme environmental factors lead to changes in the metabolism of the body and, in particular, to the predominant use of proteins and fats. The aim of our study was to reveal seasonal differences in the blood plasma fatty acid profile of people with evolutionarily developed mechanisms of adaptation to the specific conditions of the North. The subjects of the study were young male aborigines of the North (Yakuts), virtually healthy volunteers whose mean age was 19.1 ± 2.2 (n = 26). Venous blood samples were collected in the morning from 8:00 am to 9:00 am in different seasons (summer, fall, and winter). Temperature variations during these seasons were more than 100 °C. Identification and determination of fatty acid (FA) concentrations in the blood plasma samples were performed using gas chromatography-mass spectrometry (GC-MS). Statistical analysis of blood plasma lipid profile data was performed using MetaboAnalyst 5.0. The results showed that the ratio of unsaturated fatty acids (USFA) to saturated fatty acids (SFA) increases by 1.8 times in winter compared to other periods (summer, and autumn). The leading role of polyunsaturated fatty acids (PUSFA) in the adaptation of the human body to interseasonal changes has been revealed. The most important role is played by the winter increase of 11,14,17-eicosatrienoic acid (omega-3) and the winter decrease of arachidonic acid, cis-11,14-eicosadienoic acid and 8,11,14-eicosatrienoic acid.

Comparative analysis of the output products of pollock and the main commercial cod fish species

The purposeof this study is to identify general trends affecting changes in the values of the output of products from pollock and other commercial species of cod fish, and also includes a comparative analysis of the nutritional value of products from pollock and cod to provide objective recommendations to consumers of fish products.Methods used: To conduct a comparative analysis, data on the output of frozen products, reference materials and publications on the characteristics of growth, puberty, seasonal changes in biological parameters, fatness coefficient for walleye pollock, northeastern arctic and Baltic cod, Pacific cod were used. In accordance with the “Methodology for determining the consumption rates of raw materials in the production of products from aquatic organisms”, in order to compare the data, the coefficients of consumption of raw materials for the production of products were recalculated.Novelty:a comparative analysis of the change in the values of the output of products from pollock and the main commercial species of cod fish was carried out for various types of cutting in conjunction with the annual dynamics of biological parameters.Result:the general trends of changes in the output of pollock, northeastern arctic, Baltic and Pacific cod were determined. Based on the results of a comparative analysis of the nutritional value of products from pollock and cod, recommendations are presented to consumers of fish products.Practical significance: it has been established that inter-s easonal changes in the output of walleye pollock products average 0,5 %, and the output of Pacific cod changes by 5,4–5,5 %, in northeastern arctic cod the difference in output by season can reach up to 5,7 %, in Baltic cod up to 4,5 %. Cod is more depleted in the pre-spawning period, unlike pollock, so pollock processing is more rational.

Unravelling net primary productivity dynamics under urbanization and climate change in the western Himalaya

Over the past few decades, climate change and urban expansion have strongly affected vegetation dynamics and overall carbon sink capacity of Himalayan ecosystem. However, the contribution of these two key factors on varying spatio-temporal scales in Himalayan landscapes still lacks in profound analyses. The present study takes Dharamsala and Pithoragarh urban landscapes as examples and uses the Enhanced Spatial and Temporal Adaptive Reflectance Fusion Model (ESTARFM) as the image fusion technique to generate highly resolved, both spatially (30 m) and temporally (monthly), NDVI images. These are used as inputs for Carnegie-Ames-Stanford Approach (CASA) model for Net Primary Productivity (NPP) estimation over the past two decades (2000–2020). During the study period, the NPP loss due to urbanization was 2065.43 kg C in Dharamsala and 401.07 kg C in Pithoragarh. Climate change, measured in terms of interseasonal changes in temperature, rainfall and solar radiation, had considerably contributed to the NPP variations of vegetated areas in both the study sites, however its contribution ratio was relatively lower than residual factors. There was a significant distribution gradient between how and where urban expansion and climate change influenced the NPP. Urban expansion impacts NPP more in plain areas corresponding to new urban land developments while climate change impacts NPP in high elevation mountainous regions dominated by Oak species. The observed declining trend of NPP under the current threat of urban expansion and climate change in the Himalaya highlights and invites the need of attributing importance to ecological issues. The findings of our study encompassing complex Himalayan landscapes could offer scientific perspectives for the management of ecological environment of highly fragile and vulnerable landscapes of the Himalaya.

Hydrologic changes of in-situ gravimetry

Inter-seasonal and geodynamics-related gravity changes are important geoscientific signals that are extractable from gravimeter observations after removing background information as local hydrology gravity effect. With two superconducting gravimeters (SGs: OSG-053 and iGrav-007) located in different tectonic units, continuous global navigation satellite system data and absolute gravity observations, Wuhan, China, is an ideal location for investigating the effects of gravity resulting from significant local hydrology mass variations. We have processed approximately 26 months of gravity data collected from the SGs in Wuhan and obtained residuals of [Formula: see text] for OSG-053 and [Formula: see text] for iGrav-007. The hydrological observations indicate an estimated gravity increase of [Formula: see text] near iGrav-007, which mainly results from an increase in unconfined water level with an aquifer-specific yield of approximately 0.1. However, the gravity changes around OSG-053 are mainly from soil moisture and reach −[Formula: see text]. The soil type, thickness, and water content parameters are obtained from hydrogeological surveys and drilling data. The deep confined water level rises by 2.5 m, which introduces a [Formula: see text] gravity variation with a specific storage approximately 0.00001 from the field unsteady-flow pumping test. The modeled gravity is approximately [Formula: see text] around OSG-053 and [Formula: see text] around iGrav-007, in accordance with the observed gravity variations. The difference in gravity changes between the two SG observations can be explained by different local water storage environments. Our results suggest that unconfined and soil water significantly impact the in-situ gravimetry, and that further detailed hydrogeological surveys are required. A combined investigation of gravity and water levels can be a useful approach for monitoring aquifer storage conditions and groundwater management.

Seasonal evolution and interseasonal changes in polar mesospheric clouds at high latitudes in the Southern Hemisphere

The total areas and other related characteristics of polar mesospheric clouds of the Southern Hemisphere are determined on the basis of the processing of images obtained from the AIM satellite mission. Daily images have been analyzed from 2007 to 2008 to 2019–2020 austral summer seasons. The set of the analyzed data allowed us to study the features of seasonal and inter-seasonal changes in the development of polar mesospheric clouds (PMCs). Long-term temporal changes in such parameters as the maximum and integral areas of the cloud field, the date of the first appearance and disappearance of PMCs, as well as their season durations have been considered in detail. The conclusion about the non-random nature of changes in these characteristics in some seasons is substantiated. It is possible that the PMC evolution is influenced by fluctuations in weather and climatic conditions in the Antarctic region. This assumption is supported by both the relationship between the intensity of mesospheric clouds development in the Southern Hemisphere and variations in seasonal mean (in the context of the clouds existence) temperatures in Antarctica as well as between the stable similarity in seasonal changes in temperature and PMC field areas.

Fry Survival Rate as a Predictive Marker of Optimal Production of Silver Carp (Hypophthalmichthys molitrix, Valenciennes 1844): A Biostatistical Study in Deroua Fish Farm, Morocco

Several indicators show that the world population is rapidly increasing with prospects of reaching close to 10 billion people in 2050. Optimal production of fish is a tentative goal to ensure human feeding and resources sustainability. The present study was performed on eggs of the silver carp, collected during the breeding season of consecutive years with different environmental temperature profiles at the Deroua Fisheries Station to evaluate the seasonal and inter-seasonal changes of eggs quality in order to promote a predictive marker for optimal production of silver carp. The viability of the obtained eggs was detected using ANOVA followed by the Tukey test to analyze fertilization rate, embryos survival rate, and fry survival rate. Data analysis showed no significant difference in the fertilization and survival rate of the embryos during the two breeding seasons, and therefore these can not be used as an adequate criterion to predict the viability of the fry of silver carp. Although the survival rate of the fry did not change during the first season, it changed significantly during the second when there was an increase in the environmental temperature. This factor could be responsible for the disturbance of the females' oogenesis and consequently the degradation of the eggs' quality. The results showed that the fry survival rate could be used as a parameter to predict the yield of silver carp production rather than the success of fertilization and the survival of embryos. This paper discusses the importance and scope of this approach.

Diagnosis of CO2 dynamics and fluxes in global coastal oceans.

Global coastal oceans as a whole represent an important carbon sink but, due to high spatial–temporal variability, a mechanistic conceptualization of the coastal carbon cycle is still under development, hindering the modelling and inclusion of coastal carbon in Earth System Models. Although temperature is considered an important control of sea surface pCO2, we show that the latitudinal distribution of global coastal surface pCO2 does not match that of temperature, and its inter-seasonal changes are substantially regulated by non-thermal factors such as water mass mixing and net primary production. These processes operate in both ocean-dominated and river-dominated margins, with carbon and nutrients sourced from the open ocean and land, respectively. These can be conceptualized by a semi-analytical framework that assesses the consumption of dissolved inorganic carbon relative to nutrients, to determine how a coastal system is a CO2 source or sink. The framework also finds utility in accounting for additional nutrients in organic forms and testing hypotheses such as using Redfield stoichiometry, and is therefore an essential step toward comprehensively understanding and modelling the role of the coastal ocean in the global carbon cycle.

Mesozooplankton in the Kola Transect (Barents Sea): Autumn and winter structure

The spatial distribution of mesozooplankton was investigated in relation to environmental conditions along the Kola Transect (69°30′–79°00′N, 33°30′E) during autumn (September 2011) and early winter (mid-November 2012). Mesozooplankton abundance averaged 964 and 740 individuals m−3 and biomass averaged 55 and 32 mg dry mass m−3 in 2011 and 2012, respectively. Cluster analysis showed good accordance of the mesozooplankton assemblages with the three main types of water masses present in the region. The first assemblage, dominated by Calanus finmarchicus and Oithona similis, but including neritic taxa, was associated with Murmansk Coastal Water. The second assemblage, with Calanus spp. contributing the majority of the total mesozooplankton biomass, was connected with Atlantic waters. The third assemblage, dominated by Calanus glacialis, was associated with cold Arctic waters. Redundancy analysis revealed that the explanatory factors significantly influencing the community structure of mesozooplankton were surface and bottom temperature, and depth of the sampling layer. Almost 64% of the total mesozooplankton fluctuations could be explained by changes in these environmental variables. Inter-seasonal changes in the structure of mesozooplankton were associated with higher abundances of Calanus hyperboreus, Copepoda nauplii, Microsetella norvegica, Aglantha digitale, Oikopleura vanhoeffenni, and Mertensia ovum and lower numbers of Oithona atlantica and young stages of Paraeuchaeta spp. in September 2011. Regional and seasonal comparisons of the total mesozooplankton biomass observed in the present study with sample data from the summer of 2003–2012 suggest that the mean values were higher in autumn season of 2011 due to differences in sampling layers.

Mapping Change Detection of LULC on the Cameroonian Shores of Lake Chad and its Hinterland through an Inter-Seasonal and Multisensor Approach

The aim of this study is to assess the land use/land cover (LULC) inter-seasonal changes along the Cameroonian shores of Lake Chad and its hinterland using the four generations of Landsat sensors images of MSS, TM, ETM+ and OLI. Identification of land use/land cover inter-seasonal changes is based on classification by Support Vector Machines (SVMs) algorithm. Three major spatial classes of objects are identified: open water, vegetation and marshlands, and bare soils. The results show that, bare soils class has the higher rate, and can reach 67.57% of the study area extent. Moreover, land use/land cover change from one season to another or from one decade to another can be closely linked to evolution of climate conditions. Then open water areas vary little with rate of 1.94% and 7.6% for inter-seasonal changes, and rate of 5.62% and 63.05% for inter-annual changes. Compared to open water, vegetation and marshlands has the most important variation, that is 583.59%. In addition, proportions of bare soils that vary are different between dry seasons and rainy seasons, with a lower and a higher rate of 5.38% and 82.8%. This leads to the conclusion that occupation in the study area is dominated by bare soils principally; occupation class that is most affected by changes is vegetation and marshlands followed by bare soils and then open water and marshlands.

Natural ocean acidification at Papagayo upwelling system (north Pacific Costa Rica): implications for reef development

Abstract. Numerous experiments have shown that ocean acidification impedes coral calcification, but knowledge about in situ reef ecosystem response to ocean acidification is still scarce. Bahía Culebra, situated at the northern Pacific coast of Costa Rica, is a location naturally exposed to acidic conditions due to the Papagayo seasonal upwelling. We measured pH and pCO2 in situ during two non-upwelling seasons (June 2012, May–June 2013), with a high temporal resolution of every 15 and 30 min, respectively, using two Submersible Autonomous Moored Instruments (SAMI-pH, SAMI-CO2). These results were compared with published data from the 2009 upwelling season. Findings revealed that the carbonate system in Bahía Culebra shows a high temporal variability. Incoming offshore waters drive intra- and interseasonal changes. Lowest pH (7.8) and highest pCO2 (658.3 µatm) values measured during a cold-water intrusion event in the non-upwelling season were similar to those minimum values reported from upwelling season (pH = 7.8, pCO2 = 643.5 µatm), unveiling that natural acidification also occurs sporadically in the non-upwelling season. This affects the interaction of photosynthesis, respiration, calcification and carbonate dissolution and the resulting diel cycle of pH and pCO2 in the reefs of Bahía Culebra. During the non-upwelling season, the aragonite saturation state (Ωa) rises to values of > 3.3 and during the upwelling season falls below 2.5. The Ωa threshold values for coral growth were derived from the correlation between measured Ωa and coral linear extension rates which were obtained from the literature and suggest that future ocean acidification will threaten the continued growth of reefs in Bahía Culebra. These data contribute to building a better understanding of the carbonate system dynamics and coral reefs' key response (e.g., coral growth) to natural low-pH conditions, in upwelling areas in the eastern tropical Pacific and beyond.

Impact of inter-seasonal solar variability on the association of lower troposphere and cold point tropopause in the tropics: Observations using RO data from COSMIC

Association of lower tropospheric variations with the cold point tropopause (CPT) is examined on inter-seasonal basis over the tropical region (30°N-30°S) during 2007–2010 using COSMIC/FORMOST-3 Radio Occultation (RO) data. Temperature analyses for this association are shown over different regions of the globe having contrast topography namely over Western Pacific sector, Indian sector, and African sector. Correlation coefficient (r), taken as a measurement of association, show specific longitudinal differences between the lower troposphere (from 1km to 5km height) and the CPT. The northern and southern hemispheres show contrast coupling of temperature variation between lower tropospheric region and the CPT. Land and ocean effects are found to contribute in a different way to the correlation coefficient. Analyses show symmetrical structure of ‘r’ on both sides of the equator over the African region, as data include mostly land region on both side of equator. Data represent positive correlation (r~0.5) over 15°–20° latitudes on either side of the equator over the African region, suggesting strong hold of the inter-seasonal variation of solar diabatic heating influence over the tropic of Cancer and tropic of Capricorn. On the other hand, there is a contrast behaviour over the Indian region, ‘r’ is nearly negative (~−1.0) each year in the southern hemisphere (SH) and positive (~0.4) in the northern hemisphere (NH) with a maxima near tropic of Cancer. Western Pacific region is found to display a linear increase in ‘r’ from negative (~−1.0) in SH to positive (~0.8) in NH. In general, ‘r’ (positive) maximizes over the land region around 15°–20° latitudes, suggesting a control of in phase inter-seasonal solar heating on the coupling of boundary layer/lower troposphere and CPT region, whereas it turns negative over water body. Analyses suggest that variabilities in CPT over different regions of globe show significant inter-seasonal association with the lower troposphere. Thus CPT variabilities are not only governed by QBO, ENSO, gravity waves and Kelvin wave system as reported in earlier studies but also considerably affected by inter-seasonal changes taking place in the lower troposphere.

Seasonal variation in pans in relation to limno-chemistry, size, hydroperiod, and river connectivity in a semi-arid subtropical region

Seasonal pans are hydrologically dynamic, with significant changes in water volume and depth in response to high evaporation, infiltration rates and inundation events. Intra-seasonal and inter-seasonal changes in endorheic and floodplain pans in relation to limnology, size, hydroperiod, and river connectivity were studied over two rainfall seasons across 36 pans at the Save Valley Conservancy. In the study region, floodplain pans were identified as pans that had connectivity with the Save River, while the endorheic pans (large and small) were hydrologically isolated basins. Seasonal trends for physico-chemical variables were initial low and gradual increased for both rainfall seasons. Significant inter-seasonal differences for several physico-chemical variables were observed. No significant differences in physico-chemical variables were observed between large and small endorheic pans, with the except for vegetation cover, which was higher in large pans. Floodplain pans differed from the endorheic systems in pH, conductivity, nutrients and suspended solids. Connectivity was found to be insignificant, as connections between these systems were probably too infrequent. Seasonal pans were uniquely distinguished by their morphometric, physico-chemical and hydrological characteristics. Inevitably, they are vulnerable to climate change with the extent of their resilience currently unknown.

Brown Bear Winter Feeding Ecology in the Area with Supplementary Feeding — Eastern Carpathians (Slovakia)

ABSTRACT We performed snow tracking of brown bear (Ursus arctos) in the area of the Eastern Carpathians affected by supplementary feeding during the winter periods from 2007 to 2013. On each snow track we recorded all food habits and collected all scats. From these data we calculated occurrence frequency of food habits on snow tracks, occurrence frequency, volumetric proportion and energy values of food items in scats. We revealed that: i) the most frequent food source on snow tracks was corn from supplementary feeding places for ungulates (FOST = 64%); ii) crops for ungulates was the most important food group found in scat samples of bears (EDEC = 61%, EDECST = 53%); iii) the analysis of the inter-seasonal (late autumn, winter and early spring) changes in winter bear diet based on scat analyses revealed decreasing importance of hard mast and fruit, and increasing importance of invertebrates, herbs and wood biomass and crops for ungulates from autumn to spring; iv) bears searched for food at lower elevati...

Evaluation of LST downscaling algorithms on seasonal thermal data in humid subtropical regions of India

Thermal image downscaling algorithms use a unique relationship between land surface temperature (LST) and vegetation indices (e.g. normalized difference vegetation index (NDVI)). The LST–NDVI correlation and regression parameters vary in different seasons depending on land-use practices. Such relationships are dynamic in humid subtropical regions due to inter-seasonal changes in biophysical parameters. The present study evaluates three downscaling algorithms, namely disaggregation of radiometric surface temperature (DisTrad), sharpening thermal imagery (TsHARP), and local model using seasonal (25 February 2010, 14 April 2010, and 26 October 2011) thermal images. The aggregated Landsat LST of 960 m resolution is downscaled to 480, 360, 240, and 120 m using DisTrad, TsHARP, and the local model and validated with aggregated Landsat LSTs of a similar resolution. The results illustrate that the seasonal variability of the LST–NDVI relationship affects the accuracy of the downscaling model. For example, the accuracy of all algorithms is higher for the growing seasons (February and October) unlike the harvesting season (April). The root mean square error of the downscaled LST increases from 480 to 120 m spatial resolution in all seasons. The models are least suitable in water body and dry-river bed sand areas. However, the downscaling accuracy is higher for NDVI > 0.3. The present study is useful to understand the applicability of the downscaling models in seasonally varied landscapes and different NDVI ranges.

Characterization of Organic Phosphorus Form and Bioavailability in Lake Sediments using P Nuclear Magnetic Resonance and Enzymatic Hydrolysis.

Lake sediments are known to be a significant source of phosphorus (P) to plankton populations under certain biogeochemical conditions; however, the contribution of sediment organic P (P) to internal P loads remains poorly understood. We investigated P speciation and bioavailability in sediments collected over multiple months from a shallow, eutrophic bay in Lake Champlain (Missisquoi Bay, VT) using solution P nuclear magnetic resonance (NMR) spectroscopy and enzymatic hydrolysis (EH) analysis of sediments collected during years with (2008) and without (2007) algal blooms. Sediments collected during bloom onset (July) and peak bloom (August) months contained the largest proportion of enzyme-labile P, whereas pre- and postbloom sediments were primarily composed of nonlabile P. Monoester P to diester P ratios changed with respect to depth, particularly during bloom periods. Monoester P and DNA accumulation, likely from settling particulate matter, began at the onset of the bloom and continued into October 2008 during the postbloom period. The disappearance of inositol hexakisphosphate stereoisomers and the generation of orthophosphate at lower sediment depths was also evident in August 2008. Principal components analysis of EH and NMR species proportions confirmed differences between sediment cores collected during bloom onset and peak bloom, compared with pre- and postbloom sediments. Large enzyme-labile and P species proportions corresponded to increased sediment P flux and reduced manganese and iron species in porewater. These findings suggest that interseasonal changes in P speciation may influence P mobility in sediments and contribute to important feedback dynamics between biological productivity and sediment water interface geochemistry.

Assessment of inter-seasonal temperature and precipitation changes under global warming over Setif high plains region, vulnerability and adaptation

Purpose – The purpose of this paper is to assess the inter-seasonal temperature and precipitation changes in Setif high plains region under future greenhouse gas emissions, by using four general circulation models (GCMs) output data between three time slices of twenty-first century. The objective is to show the vulnerability of the region and the strategy of adaptation to these changes. Design/methodology/approach – This study investigates likely changes in seasonal temperature and precipitation over Setif high plains region (North East of Algeria) between three time slices: 2025, 2050 and 2075. The projections are based on the SRES A2 and B2 scenarios. MAGICC-SCENGEN 5.3v.2 was used as a tool for downscaling the four selected GCMs output data. The vulnerability of the region, coupled with the possible impacts climate change, stresses the need for adaptive strategies in key sectors in the region for the long term sustainable development. Findings – The results for change in seasonal temperature indicate a general warming under the two scenarios till the year 2075.The results of GFDLCM21 and GFDLCM20 show a general reduction of spring and autumn precipitations and an increase in winter and summer. BCCRBCM2 predicts a decrease in winter, spring and summer precipitations and an increase in autumn. Climate change, as well as increases in climate variability, will alter precipitation, temperature and evaporation regimes, and will increase the vulnerability of Setif high plains to changes in hydrological cycles. Climate and weather forecasting coupled with biotechnological advances in improving crop yields and tolerances to aridity, is likely to bring significant payoffs for strategy of adaptation in the field of agricultural water management. Originality/value – This work is one of the first to study inter-seasonal temperature and precipitation changes under global warming over the region, and suggest some adaptive strategies to limit the effect of these changes.

Inter-seasonal variability in baseflow recession rates: The role of aquifer antecedent storage in central California watersheds

Baseflow recession rates vary inter-seasonally in many watersheds. This variability is generally associated with changes in evapotranspiration; however, an additional and less studied control over inter-seasonal baseflow recession rates is the effect of aquifer antecedent storage. Understanding the role of aquifer antecedent storage on baseflow recession rates is crucial for Mediterranean-climate regions, where seasonal asynchronicity of precipitation and energy levels produces large inter-seasonal differences in aquifer storage. The primary objective of this study was to elucidate the relation between aquifer antecedent storage and baseflow recession rates in four central California watersheds using antecedent streamflow as a surrogate for watershed storage. In addition, a parsimonious storage–discharge model consisting of two nonlinear stores in parallel was developed as a heuristic tool for interpreting the empirical results and providing insight into how inter-seasonal changes in aquifer antecedent storage may affect baseflow recession rates. Antecedent streamflow cumulated from the beginning of the wateryear was found to be the strongest predictor of baseflow recession rates, indicating that inter-seasonal differences in aquifer storage are a key control on baseflow recession rates in California watersheds. Baseflow recession rates and antecedent streamflow exhibited a negative power-law relation, with baseflow recession rates decreasing by up to two orders of magnitude as antecedent streamflow levels increased. Inference based on the storage–discharge model indicated that the dominant source of recession flow shifted from small, rapid response aquifers at the beginning of the wet season to large, seasonal aquifers as the wet season progressed. Aquifer antecedent storage in California watersheds should be accounted for along with evapotranspiration when characterizing baseflow recession rates.