Winter Rains Research Articles

Along the Tapajós by Fernando Vilela

Reviewed by: Along the Tapajós by Fernando Vilela Miriam Larson Vilela, Fernando Along the Tapajós; written and illus. by Fernando Vilela; tr. by Daniel Hahn. Amazon Crossing Kids, 2019 [40p] Trade ed. ISBN 978-1-5420-0868-6 $17.99 E-book ed. ISBN 978-978-1-5420-0867-9 $4.99 Reviewed from galleys Ad 4-7 yrs In this picture book from Brazil, Cauã and his family live in the Amazon rainforest on the river Tapajós and go to school via motorboat. Today, as class is ending, the sky darkens and the winter rains arrive. Cauã and his sister head home to help their family pile belongings onto big boats and move to higher ground; they find a place in the rainforest, build a new hut, and settle into their hammocks, but then Cauã's sister realizes they've left their beloved pet turtle back home. Watery landscapes created with woodcuts in red, yellow and green beautifully evoke the long, rippling river; people are drawn in digital ink with collage prints decorating their clothes and luggage, giving them a merry presence even as they are deluged by rains. The journey to school will be a relatable discussion topic for children who will delight in sharing their own (likely alligator-free) trips to school or winter routines. The turtle rescue, however, turns into a last-minute fantastical adventure scenario (including an anaconda that ties itself in a knot), which jars against the warm daily-life story of the rest of the book and ends the story on a cheesy note. Nonetheless, it's a cheerful introduction to a way of life unfamiliar to most kids, who will enjoy the river life, houses on stilts, and ambient wildlife. There's no pronunciation guide [End Page 143] for character names, but back matter include information about the Tapajós and a note from the author. Copyright © 2019 The Board of Trustees of the University of Illinois

USING WATER BALANCE TO ASSESS THE GROUNDWATER RECHARGE IN THE AREA BETWEEN RUTBA AND DHABAA, WESTERN OF IRAQ

The study area is located in Al-Rutba city, Al-Anbar Governorate, western Iraq. The metrological data were collected during 1981 – 2016, and used to assess the climatic condition for the study area. The total annual rainfall was 113.3 mm and relative humidity was 47.1%, while the monthly average temperature was 20.1 °C, evaporation was 3074.3 mm, the wind speed was 2.6 m/s with a prevailing direction along the year was NW 29.2%. Data derived from the ratio of wind direction and sunshine duration was 9.2 h/day. The climate of the study area is described as an arid and relatively hot in summer, and cold with low rain in winter. During the 35 years' comparison period, the highest potential evapotranspiration value was 175.82 mm during July and August, while the lowest value was 7.758 mm in January, while the total amount was 970.612 mm. The highest value of the corrected evapotranspiration was 212.74 mm in July and the lowest value was 6.78 mm in January, while the total amount was 1072.021 mm. Water surplus was recorded in the study area was 19.849% of the total rainfall which was equivalent to 113.3 mm. The study area consisted of a thin layer (<0.1 m) of sandy soil, therefore, this thin layer was not considered. A number of key findings are presented which pertain to; the type of rainfall event, wind conditions, and the location. Hence, the value of groundwater recharge was 22.489 mm with a rate of 19.849% which represents the percentage of groundwater recharge from the total rainfall.

BALANÇO HÍDRICO E CLASSIFICAÇÃO CLIMÁTICA DE KÖPPEN E THORNTHWAITE NO MUNICÍPIO DE FEIRA DE SANTANA (BA) / WATER BALANCE AND KÖPPEN CLIMATE CLASSIFICATION AND THORNTHWAITE IN THE MUNICIPALITY OF FEIRA DE SANTANA (BA)

O estudo da meteorologia se baseia nos fenômenos atmosféricos, seu comportamento e interações físicas, químicas e dinâmicas com os demais elementos da superfície terrestre. O objetivo deste trabalho foi caracterizar climaticamente o município de Feira de Santana (BA), quanto à disponibilidade de água para o cultivo agrícola, utilizando os dados disponibilizados pelo INMET, os quais foram processados através do método de balanço hídrico climático, a partir do qual se obteve o índice hídrico, índice de aridez e índice de umidade, e auxílio das chaves de classificação de Thornthwaite. O balanço hídrico mostrou que o município apresenta uma ETP de 1431,7 mm ano-1, ETR de 720,7 mm ano-1, DEF de 711,0 mm ano-1 e EXC igual a zero. O tipo climático pela metodologia de Köppen é “Asa”, megatérmico com chuvas de inverno e verão quente, enquanto que a de Thornthwaite é C1w2A’a’, clima Sub-úmido seco com largo excesso de verão, megatérmico e com concentração de evapotranspiração potencial no verão igual a 31,2%. O município de Feira de Santana apresenta uma alta ETP, influenciada pelas altas temperaturas. O período de menor deficiência hídricas é registrado nos meses de maio, junho e julho, sendo indicado para os cultivos de sequeiro. O método de classificação climática de Thornthwaite apresenta maior detalhes que o de Köppen.

Seasonality of nitrogen balances in a Mediterranean climate watershed, Oregon, US.

We constructed a seasonal nitrogen (N) budget for the year 2008 in the Calapooia River Watershed (CRW), an agriculturally dominated tributary of the Willamette River (Oregon, U.S.) under Mediterranean climate. Synthetic fertilizer application to agricultural land (dominated by grass seed crops) was the source of 90% of total N input to the CRW. Over 70% of the stream N export occurred during the wet winter, the primary time of fertilization and precipitation, and the lowest export occurred in the dry summer. Averaging across all 58 tributary subwatersheds, 19% of annual N inputs were exported by streams, and 41% by crop harvest. Regression analysis of seasonal stream export showed that winter fertilization was associated with 60% of the spatial variation in winter stream export, and this fertilizer continued to affect N export in later seasons. Annual N inputs were highly correlated with crop harvest N (r2=0.98), however, seasonal dynamics in N inputs and losses produced relatively low overall nutrient use efficiency (41%), suggesting that hydrologic factors may constrain improvements in nutrient management. The peak stream N export during fall and early winter creates challenges to reducing N losses to groundwater and surface waters. Construction of a seasonal N budget illustrated that the period of greatest N loss is disconnected from the period of greatest crop N uptake. Management practices that serve to reduce the N remaining in the system at the end of the growing season and prior to the fall and winter rains should be explored to reduce stream N export.

Late Quaternary micromammals and the precipitation history of the southern Cape, South Africa

AbstractThe southern Cape of South Africa is important to understanding regional climate because it straddles the transition between the winter and summer rainfall zones. We examine late Quaternary changes in rainfall seasonality and aridity through analysis of micromammal assemblages from three sites: Boomplaas Cave and Nelson Bay Cave in the aseasonal rainfall zone and Byneskranskop 1 in the winter rainfall zone. Our interpretation is based on analysis of 123 modern micromammal assemblages accumulated by barn owls (Tyto alba), which empirically links species composition to climate. The Pleistocene record (∼65 to 12 ka) from Boomplaas Cave, together with the last glacial maximum (LGM) samples from Nelson Bay Cave, indicates enhanced winter rainfall, especially during the LGM. Boomplaas Cave documents progressive aridification from the LGM to the earliest Holocene, followed by a return to moderately humid conditions through the Holocene. Byneskranskop 1 indicates a dominance of winter rains over the last 17 ka and a shift from an arid middle Holocene to a humid later Holocene. Agreement between the micromammal record and other local and regional proxies reinforces the potential of southern African micromammal assemblages as paleoclimate indicators.

Application of PCR based diagnostics in the exploration of Parastagonospora nodorum prevalence in wheat growing regions of Himachal Pradesh

Stagonospora leaf and glume blotch (SLGB) of wheat caused by Parastagonospora nodorum (formerly Stagonospora nodorum) has recently emerged as a major problem in changing climatic conditions of Himachal Pradesh (HP), especially during delayed winter rains. In the present studies symptomatology, morpho-cultural as well as molecular marker based identification showed the prevalence of disease in the state and conclusively proved that leaf and glume blotch of wheat is caused by P. nodorum. The test pathogen showed 100% homology with other reported P. nodorum isolates by rDNA (ribosomal DNA) analysis. In addition, the amplification of rDNA region of 36 P. nodorum isolates representing various agro-ecological areas of HP and one infected wheat leaf sample generated an amplicon of ~ 449-bp with JB433 (5′-ACACTCAGTAGTTTACTACT-3′) and JB434 (5′-TGTGCTGCGCTTCAATA-3′) P. nodorum specific primer pair whereas no amplification was observed with the genomic DNA of Septoria titici, Stemphylium vesicarium and healthy wheat leaf sample. This study on integration of morpho-cultural and microscopic methods along with PCR based technique could form basis for routine diagnosis of the SLGB in wheat samples during early growth stages of crop in the seed production fields.

Population trends of Peregrine Falcon in Northern Spain – Results of a long-term monitoring project

Abstract We monitored Peregrine Falcon (Falco peregrinus) population in Bizkaia, Northern Spain, during two decades (1998–2017). Our population increased from 34 to 47 territorial pairs, as did other European populations until the first years of the 21st century, and then declined until 34 territorial pairs in 2017. The combination of catastrophic events (Prestige oil spill), increasing rain in winter and spring, and direct and indirect mortality factors significantly affected incubation onset, productivity and population stability, which in turn could impact on the floater population. Rain in February significantly affected incubation onset, which showed a slight positive trend during the last decade. Juvenile females laid 12 days later than adults, and each adult female started incubation in the same dates every year. However, the proportion of juvenile females did not significantly increase as might have been expected. Moreover, productivity was inversely related to incubation onset dates. Rain in April and May also affected productivity, and combined with short term extreme weather events determined a decreasing productivity during the last decade. Moreover, apart from human persecution (which caused 40.30% of the known deaths of Peregrines), we found 18 cases of breeders affected by infectious diseases, also related to weather. The combined effects of these factors, and the low availability of adequate nesting sites, negatively affected (i) territorial populations, (ii) productivity, and (iii) floater population, which in turn also determined territorial population and productivity.

Mortality of Native and Non-native Fishes during Artificial Breaching of Coastal Lagoons in Southern and Central California

Fishes of California coastal streams and associated coastal lagoons have adapted to the Mediterranean-style rainfall cycle. Winter rains open the lagoons to the ocean; subsequent lack of rain and seasonal changes in beach dynamics typically closes them for much of the year. Dry and wet season artificial breaching or opening of barrier sand berms has been suspected to disrupt fish populations and lead to mortality of many aquatic organisms including federally endangered species. Such breaches have been rarely observed and then only after at least a few days or more have passed. Artificial breachings of three lagoons have been observed during or within a few hours after breaching and provide documentation of extensive disruption and mortality of aquatic organisms. These observations, Aliso Creek, Orange County (1975), Santa Clara River, Ventura County (2010), and Corcoran Lagoon, Santa Cruz County (2014-2015), confirmed many changes and effects of these events, including mortality of the federally endangered northern and southern tidewater gobies and southern steelhead. Despite the many ostensibly beneficial and non-faunal related reasons for breaching, our observations confirm such actions can cause considerable mortality of threatened and endangered species and are probably more severe than natural wet season breachings. Many city, county, as well as state and federal laws provide regulation of lagoon breaching to protect habitat and minimize or mitigate for impact to sensitive species and these need to be maintained and strengthened.

Seed yield and subsequent emergence pattern of subterranean clover cultivars in response to summer rain

At Lincoln University, Canterbury, seven subterranean cultivars rated in Australia as having different levels of ‘hardseedeness’ were established. Monocultures were sown in autumn and allowed to grow and set seed. Seed yields ranged from 340 to 1050 kg/ha. Heavy rain in early January 2016 resulted in a “false strike” of ≤ 4.0% of seeds during the subsequent dry February. A second emergence event in March also resulted in a “false strike” with a further 7 to 15% of total seeds lost. However, cultivars established >1000 seedlings/m2 after early winter rain, which is considered adequate for future persistence. Emergence was consistent with Australian hardseededness rankings. Cultivars with hardseed ranks <4 may be more suitable for dryland systems in New Zealand due to their early emergence and the ability to exploit the late summer and autumn rains.

Neoglacial climate anomalies and the Harappan metamorphosis

Abstract. Climate exerted constraints on the growth and decline of past human societies but our knowledge of temporal and spatial climatic patterns is often too restricted to address causal connections. At a global scale, the inter-hemispheric thermal balance provides an emergent framework for understanding regional Holocene climate variability. As the thermal balance adjusted to gradual changes in the seasonality of insolation, the Intertropical Convergence Zone migrated southward accompanied by a weakening of the Indian summer monsoon. Superimposed on this trend, anomalies such as the Little Ice Age point to asymmetric changes in the extratropics of either hemisphere. Here we present a reconstruction of the Indian winter monsoon in the Arabian Sea for the last 6000 years based on paleobiological records in sediments from the continental margin of Pakistan at two levels of ecological complexity: sedimentary ancient DNA reflecting water column environmental states and planktonic foraminifers sensitive to winter conditions. We show that strong winter monsoons between ca. 4500 and 3000 years ago occurred during a period characterized by a series of weak interhemispheric temperature contrast intervals, which we identify as the early neoglacial anomalies (ENA). The strong winter monsoons during ENA were accompanied by changes in wind and precipitation patterns that are particularly evident across the eastern Northern Hemisphere and tropics. This coordinated climate reorganization may have helped trigger the metamorphosis of the urban Harappan civilization into a rural society through a push–pull migration from summer flood-deficient river valleys to the Himalayan piedmont plains with augmented winter rains. The decline in the winter monsoon between 3300 and 3000 years ago at the end of ENA could have played a role in the demise of the rural late Harappans during that time as the first Iron Age culture established itself on the Ghaggar-Hakra interfluve. Finally, we speculate that time-transgressive land cover changes due to aridification of the tropics may have led to a generalized instability of the global climate during ENA at the transition from the warmer Holocene thermal maximum to the cooler Neoglacial.

Transference of isotopic signal from rainfall to dripwaters and farmed calcite in Mediterranean semi-arid karst

This study was conducted in Ejulve cave (Spain, southwestern Europe) over a period of four years (2013–2016) to identify the factors affecting the isotopic composition of rainfall, dripwaters, and farmed calcite. The results indicate that δ18O of rainfall in the study area was mainly controlled by the temperature effect (r2 = 0.82, p-value < 0.001) with source effect and amount effect being secondary controls. Additionally, it exhibited a seasonal pattern with lower values indicated during winter and higher in summer. The use of effective infiltration to evaluate the recharge of the epikarst is extremely important in semi-arid karst climate conditions. This analysis revealed that while the amount effect exerted a moderate control on the annual δ18O in rainfall, it had a lower influence on the isotopic variability of the rainfall potentially infiltrating the karst aquifer. The sampling of 12 drip locations in Ejulve cave indicated that seepage and seasonal drips featured similar δ18O values in dripwaters. The homogenisation process during the infiltration in the epikarst was not complete, therefore, the δ18O seasonality seen in rainfall was also observed in dripwater δ18O, albeit attenuated and lagged. With the seasonal increase in rainfall in autumn, drip rates of seasonal and seepage groups increased within a few weeks. However, the lower δ18O of autumn–winter rain was observed in dripwaters with a lag as long as 21 weeks. The δ18O in farmed calcite showed a small variation of 0.11‰ while the δ13C varied seasonally with a variation of about 0.22‰ and indicated higher values during summer and autumn and lower values in winter and spring. Seasonal and seepage sites exhibited similar δ18O variability. However, δ13C was more positive in seepage sites and was enhanced by degassing kinetics to produce a variability of up to 0.42‰ in contrast to the 0.29‰ observed in the seasonal sites. The δ18O of calcite showed dependence on the δ18O of dripwater with a weak influence of the drip rate. However, δ13C exhibited a higher correlation with the drip rate and high δ13C was explained by enhanced degassing and low water availability while low δ13C values were in concordance with higher microbial activity, vegetation productivity, and greater water availability. The ventilation of the cave during late autumn through spring favoured the higher calcite deposition rates found during that time.

Floristic and structural assessment of Australian rangeland vegetation with standardized plot-based surveys.

We describe and correlate environmental, floristic and structural vegetation traits of a large portion of Australian rangelands. We analysed 351 one hectare vegetation plots surveyed by Australia’s Terrestrial Ecosystem Research Network (TERN) using the AusPlots Rangelands standardized method. The AusPlots Rangelands method involves surveying 1010 one meter-spaced point-intercepts (IPs) per plot. At each IP, species were scored, categorised by growth-form, converted to percentage cover as the input for the plot x species matrix. Vegetation structure is depicted by growth-form configuration and relative importance. The floristic and structural distance matrices were correlated with the Mantel test. Canonical correspondence analysis (CCA) related floristic composition to environmental variables sourced from WorldClim, the Atlas of Living Australia and TERN’s Soil and Landscape Grid. Differences between clusters were tested with ANOVA while principal component analysis (PCA) ordered the plots within the environmental space. Our plot x species matrix required segmentation due to sparsity and high β-diversity. Based on the ordination of plots latitude within environmental space, the matrix was segmented into three “superclusters”: the winter rain and temperate Mediterranean, the monsoonal rain savannas and the arid deserts. Further classification, with the UPGMA linkage method, generated two, four and five clusters, respectively. All groupings are described by species richness, diversity indices and growth form conformation. Several floristic disjunctions were apparent and their possible causes are discussed. For all superclusters, the correspondence between the floristic and the structural or growth form matrices was statistically significant. CCA ordination clearly demarcated all groupings. Aridity, rainfall, temperature, seasonality, soil nitrogen and pH are significant correlates to the ordination of superclusters and clusters. At present, our results are influenced by incomplete sampling. As more sites are surveyed, this pioneer analysis will be updated and refined providing tools for the effective management of Australian rangelands.

Soil carbon and nitrogen responses to snow removal and concrete frost in a northern coniferous forest

Climate change in northeastern North America is resulting in warmer winters with reduced snow accumulation. Soils under a thin snowpack are more likely to experience freeze–thaw cycles, disrupting carbon (C) and nitrogen (N) transformations. We conducted a 2 year snow removal experiment in Maine to study the effects of soil freezing on soil C and N processes. O horizon soils were sampled during winter and spring of 2015 and 2016, and they were analyzed for labile inorganic N and water-extractable organic carbon (WEOC) concentrations, specific ultraviolet absorbance (SUVA254), and potential net N mineralization. The winter of 2015 was cold and snowy, whereas 2016 was warm with a shallow, short-term snowpack. Snow removal caused the soils to freeze, but winter rain-on-soil events in 2015 resulted in the formation of concrete frost, as opposed to granular frost in 2016. Concrete frost increased soil ammonium (NH4+-N) and WEOC concentrations and decreased SUVA254, which we attribute to microbial cell lysis. In contrast, granular frost did not alter soil nutrient concentrations, reflecting limited microbial distress. Our study demonstrates that moisture content influences the intensity of soil freezing, highlighting the importance of snowpack depth and winter rain events in regulating winter and spring biogeochemical processes and nutrient availability.

Pleistocene paleosols associated with megafauna in Northwestern Mexico: Paleoecological inferences

The pedological cover of the state of Sonora, in northern Mexico, is predominantly composed of moderately developed red soils that evidence processes of weathering, humification, rubification, neoformation of clay, and carbonation, classified as Cambisols according to the WRB. These soils constitute a pedological unit denominated the San Rafael Paleosol (SRP). In contrast, gray soils are recorded in some sites located in semi-closed basins and are characterized by processes of weathering, neoformation of clay, reductomorphism and carbonation. These soils developed during the late Pleistocene under a semi-arid and cold climate, slightly more humid than the present one, with winter dominant rains, and marked seasonal changes. These paleosols are associated with remnants of Pleistocene Rancholabrean fauna of diverse composition, associated with arid and humid climates, demonstrating local climatic variations much more complex than at present. This paper evaluates the physical, chemical and micromorphological attributes of paleosols located in the San Francisco and El Arenoso ranches in the north of Sonora. The analyses are undertaken in order to identify the main pedogenetic processes and to establish the predominant environmental conditions during their formation, specifically the particular characteristics associated with semi-enclosed basins that allowed the accumulation of water and the formation of ponds. At both sites remains of Pleistocene megafauna have been found associated with paleosols. These results are contrasted with previous paleopedological studies and the paleontological record, permitting a broader discussion of regional paleoclimatic trends.

Brungarians Use it Differently! Children’s Understanding of Artifact Function as a Cultural Convention

Abstract Children not only recognize the function of an artifact, but they actively protest when others use it in an atypical way. In two experiments, we asked whether children view artifact function as universal or as culturally dependent. In both experiments children watched videos of two actors who used common artifacts atypically (e.g. a woman using a fork to comb her hair). In Experiment 1A, 6-to-7-year-old children were told that the actors were either from Canada or a far away country. Children were marginally more likely to protest a Canadian using the artifact in a novel way than when the individual was from a far away country. In Experiment 1B, the familiar or unfamiliar culture was explicitly highlighted (e.g., “in Canada it snows in winter” vs. “in Brungaria it rains in winter”). Four-to-five-year-olds were also included as a comparison group. Six-to-seven-year-olds protested the atypical use when the actor was Canadian more than when the actor was Brungarian, whereas 4-to-5-year-olds protested at non-significant rates. Additionally, when asked what appropriate function of the artifact was, 6-to-7-year olds were more likely to endorse the atypical function when it was performed by a Brungarian than a Canadian, while 4-to-5-year-olds never endorsed the atypical function, regardless of condition. These findings demonstrate that while younger children view artifact function as universal, children over the age of 6 recognize that the accepted function of an artifact may vary by culture.

Using SAR satellite data time series for regional glacier mapping

Abstract. With dense SAR satellite data time series it is possible to map surface and subsurface glacier properties that vary in time. On Sentinel-1A and RADARSAT-2 backscatter time series images over mainland Norway and Svalbard, we outline how to map glaciers using descriptive methods. We present five application scenarios. The first shows potential for tracking transient snow lines with SAR backscatter time series and correlates with both optical satellite images (Sentinel-2A and Landsat 8) and equilibrium line altitudes derived from in situ surface mass balance data. In the second application scenario, time series representation of glacier facies corresponding to SAR glacier zones shows potential for a more accurate delineation of the zones and how they change in time. The third application scenario investigates the firn evolution using dense SAR backscatter time series together with a coupled energy balance and multilayer firn model. We find strong correlation between backscatter signals with both the modeled firn air content and modeled wetness in the firn. In the fourth application scenario, we highlight how winter rain events can be detected in SAR time series, revealing important information about the area extent of internal accumulation. In the last application scenario, averaged summer SAR images were found to have potential in assisting the process of mapping glaciers outlines, especially in the presence of seasonal snow. Altogether we present examples of how to map glaciers and to further understand glaciological processes using the existing and future massive amount of multi-sensor time series data.

Understanding the characteristics of riparian zones in low relief, sandy catchments that affect their nutrient removal potential

Riparian zones are considered to improve stream condition by providing a buffer between waterways and agricultural land that can intercept nutrients, but is their efficacy universal? This paper develops a conceptual model comparing the interactions of slope, soil, hydrology, vegetation and nutrient dynamics between 1) the riparian zone of an intermittent stream in a low-relief (1.6%) catchment with deep sands of low reactivity (Bingham Creek) and 2) a perennial stream in a sloped (10%) catchment with reactive soils over an impermeable layer (Lennard Brook), with a view to compare and contrast their riparian functionality. This study compared the attributes of groundwater (three rows of nested piezometers) (0.5 m,1.5 m and 2.5 m depth), stream, soil and vegetation across a transect from the stream, through the riparian zone to agricultural paddocks. In the low-relief catchment, water did not flow through the riparian zone as in a sloped catchment. Porous soils, together with a lack of slope or a confining layer meant water oscillated vertically through the soil profile over the season, with minimal horizontal movement and limited interaction with the active root zone of riparian vegetation; the intermittent stream discharged P-rich water into the riparian zone during the first flush of winter rains. The highly unreactive sands resulted in trivial P or C uptake resulting in high dissolved concentrations in adjacent streams (0.6–0.9 vs 0.001–0.002 mg/L TP, 58 vs 3 mg/L DOC for flat vs sloped catchments respectively). The high DOC in slow-moving groundwater resulted in highly reducing conditions, promoting P solubility and potentially denitrification. Litterfall from vegetation marginally improved riparian soils with better P retention relative to the adjacent paddock (3620–268 kg TP/ha storage) and reduced FRP in the groundwater relative to the stream (27 vs 80%). The conceptual model developed highlights an alternative functionality of riparian zones for low-relief catchments that challenges the assumption of riparian efficacy.

Reach specific use of spawning habitat by adult green sturgeon ( Acipenser medirostris ) under different operation schedules at Red Bluff Diversion Dam

Mature green sturgeon, Acipenser medirostris, enter rivers along the western coast of North America in late winter to late spring and migrate upriver to spawning sites. After spawning, they may leave the river or spend the summer and autumn holding in deep pools before departing from the river with the onset of winter rains. Evidence exists that the seasonal Red Bluff Diversion Dam (RBDD) was an obstacle to the upriver migration of green sturgeon in the Sacramento River in Central California. We compared the migratory movements of green sturgeon under three different dam operation schedules, including post-decommissioning, to assess the impact of this management action. The proportion of green sturgeon carrying acoustic transmitters that moved above the RBDD was higher when the gates were closed on June 15, one month later than the historical closure date of May 15, and increased again after the dam was decommissioned. The application of statistical analyses (generalized linear and additive mixed models) to the detection records of green sturgeon highlighted an improvement in connectivity after dam decommissioning. The data also indicate that interannual variation in river condition is an important driver of sturgeon presence on the spawning grounds.

Phenological Sensitivity of Early and Late Flowering Species Under Seasonal Warming and Altered Precipitation in a Seminatural Temperate Grassland Ecosystem

Shifts in flowering phenology of plants are indicators of climate change. The great majority of existing phenological studies refer solely to gradual warming. However, knowledge on how flowering phenology responds to changes in seasonal variation of warming and precipitation regimes is missing. We report the onset of 22 early (flowering before/within May) and 23 late flowering (flowering after May) species in response to manipulated seasonal warming (equal to + 1.2°C; last 100-year summer/winter warming), additional winter rainfall, and modified precipitation variability (including a 1000-year extreme drought event followed by heavy rainfall) over the growing season in two consecutive years for a species-rich temperate grassland ecosystem. The average onset of flowering (over 2 years) was significantly advanced 3.1 days by winter warming and 1.5 days by summer warming compared to control. Early flowering species responded to seasonal warming in both years, while late-flowering species responded in only 1 year to summer warming. The average onset of early flowering species was significantly advanced, 4.9 days by winter warming and 2.3 days by summer warming. Species-specific analysis showed that even within the early flowering community there were divergences. A positive correlation between plant height and shift in flowering onset was detected under winter warming (R2 = 0.20, p = 0.005). The average onsets of early and late flowering community were affected by neither winter rain nor growing season precipitation variability. Seasonal differences in warming, and particularly winter warming, might alter community dynamics among early and late flowering species which can cause shifts in the seasonal performances of temperate ecosystems.

Ecology of benthic crustaceans in the Tolten river (39°S, Araucania region, Chile)

The Cautin river is located in the Araucania region, Chile (38°S), and is characterized by alterations through human interference in its surrounding basin, by the presence of introduced salmonids, and by its mixed regime, which originates from melting snow in summer and rains in winter. The fauna of this river includes an invertebrate fauna composed of both endemic and widespread species, which has, however, been only poorly studied until now. The aim of the present study was to make a review of the ecological role of the benthic inland water crustaceans of the River Cautin, in order to understand their importance in the ecosystem of the river. The literature revealed the presence of abundant populations of amphipods and freshwater crabs as well as of aquatic insects along the river’s course. Many of these crustaceans are prey for both introduced salmonids and native fishes. Similar results have been reported for other southern Argentinean and Chilean Patagonian rivers.