Moisture and Species Effect on Water Colour Generation in an Australian Temperate Forested Catchment

Rainfall frequency, not quantity, controls isopod effect on litter decomposition

Global warming and anthropogenic activities have imposed noticeable impacts on rainfall pattern changes at both spatial and temporal scales in recent decades. Systematic diagnosis of rainfall pattern changes is urgently needed at spatiotemporal scales for a deeper understanding of how climate change produces variations in rainfall patterns. The objective of this study was to identify rainfall pattern changes systematically under climate change at a subcontinental scale along a rainfall gradient ranging from 1800 to 200 mm yr−1 by analyzing centennial rainfall data covering 230 sites from 1910 to 2017 in the Northern Territory of Australia. Rainfall pattern changes were characterized by considering aspects of trends and periodicity of annual rainfall, abrupt changes, rainfall distribution, and extreme rainfall events. Our results illustrated that rainfall patterns in northern Australia have changed significantly compared with the early period of the twentieth century. Specifically, 1) a significant increasing trend in annual precipitation associated with greater variation in recent decades was observed over the entire study area, 2) temporal variations represented a mean rainfall periodicity of 27 years over wet to dry regions, 3) an abrupt change of annual rainfall amount occurred consistently in both humid and arid regions during the 1966–75 period, and 4) partitioned long-term time series of rainfall demonstrated a wetter rainfall distribution trend across coastal to inland areas that was associated with more frequent extreme rainfall events in recent decades. The findings of this study could facilitate further studies on the mechanisms of climate change that influence rainfall pattern changes. Significance Statement Characterizing long-term rainfall pattern changes under different rainfall conditions is important to understand the impacts of climate change. We conducted diagnosis of centennial rainfall pattern changes across wet to dry regions in northern Australia and found that rainfall patterns have noticeably changed in recent decades. The entire region has a consistent increasing trend of annual rainfall with higher variation. Meanwhile, the main shifting period of rainfall pattern was during 1966–75. Although annual rainfall seems to become wetter with an increasing trend, more frequent extreme rainfall events should also be noticed for assessing the impacts of climate changes. The findings support further study to understand long-term rainfall pattern changes under climate change.

It is now widely accepted that the global climate is changing with increasing greenhouse gas concentration in the atmosphere due to human activities. There is enough evidence for more negative impacts of climate change on world agricultural sector. As an agricultural country, Sri Lanka is also experiencing some inevitable consequences due to changing rainfall onset, distribution and the amount. Standardized Precipitation Index (SPI) is a drought monitoring index which is developed for identifying rainfall anomalies with respect to the past data in the same location for specific time scales. The aim of this study was to identify the changes in rainfall patterns using SPI in Anuradhapura district which is one of the major paddy growing areas in Sri Lanka. Monthly rainfall data were collected from four Meteorological Stations viz, Anuradhapura, Maha Iluppallama, Maradankadawala and Kebithigollewa for the period of 1980-2018. Five months SPI values were computed to represent Yala & Maha cultivation seasons and 12 months SPI values were computed to represent the annual rainfall anomalies. Mann Kendal Test was used to identify the trends in selected SPI time series. The results of the study revealed that, there are significant increasing trends in total annual rainfall in Anuradhapura district indicating low risk of having drought years in future. The significant increasing trend in SPI values in Yala & Maha seasons in both Anuradhapura and Maha Iluppallama stations imply that there is a high chance of receiving enough water for cultivation in both seasons in near future. Further, a significant decrease could be observed in total annual and Yala season’s SPI values in Maradankadawala indicating a high potential of having droughts. However, Kebithigollewa does not show any significant change in total annual, Yala or Maha seasons rainfall patterns. Finally, it can be concluded that, as Anuradhapura, Maha Iluppallama and Kebithigollewa areas are getting slightly wetter, the paddy cultivation in the Western and Southwestern areas of Anuradhapura district would not be severely affected due to changing rainfall patterns. However, as Maradankadawala area is getting slightly dryer with the changing rainfall patterns, strengthening water conservation techniques would be better for paddy cultivation in the Southeastern area of Anuradhapura district in order to adapt to the incoming dry periods.

Effects of rainfall patterns on toxic cyanobacterial blooms in a changing climate: Between simplistic scenarios and complex dynamics

Climate change has a significant impact on the environment as well as the social, economic and political fabric of Australia. This paper examines historical trends in temperature and rainfall in regions of Australia which represent different climatic regimes. In this study, we analyse trends in temperature and rainfall in three selected regions (Central eastern Queensland, south west Western Australia and central east Victoria) over the past 50-100 years. Observational data for daily maximum temperature, daily minimum temperature, daily mean temperature and total annual rainfall recorded at meteorological stations in these regions have been obtained from the National Climate Centre, Australian Bureau of Meteorology (BoM). Historical trends in the observational data have been examined using time series analysis. The results indicate that Australia is experiencing rapid climate change. Over the last 100 years, Australian temperatures have increased on average by approximately 1°C. Rainfall distribution across the continent has changed during the last century and even more pronounced changes in rainfall patterns are evident over recent decades. Since the 1950s, an increase in rainfall in the northwest of Australia has been observed. In contrast, significant decline in rainfall over eastern and southwestern Australia has been recorded. Consequently, such trend as well as changes in rainfall and temperature patterns have manifested in changes of frequency of climate extremes such as droughts and floods. Detailed results of trend analysis of rainfall and temperature are presented. The results of this study are in good agreement with the findings of early studies.

As one of the main stakeholders in the fishing industry, shrimp farmers are directly affected by climate change that causes changes in seawater temperature, rainfall, and unpredictable weather patterns. Related to the issue, the threat to income may be felt by shrimp farmers. Therefore, in this study, we highlight two objectives as a basis for drawing up this article, namely (1) to understand shrimp farmers’ perceptions of climate change, and (2) to identify factors that influence farmers’ decisions in implementing adaptation strategies. There are two types of analysis that we use, namely descriptive analysis and logit regression analysis. Our findings show that the majority of shrimp farmers consider climate change manifested in the form of changes in rainfall patterns (96.21%), increases in pond water temperatures (98.71%), decreases in yield production (95.41%), and increases in shrimp pests and diseases (96.23%). The results of our logit regression analysis show that the decision-making factors of shrimp farmers are significantly influenced. These results indicate that the implementation of adaptation strategies in the fisheries sector can generate significant growth and reduce the risks posed by climate change. As a result, the government needs to encourage the development of more suitable climate change adaptation strategies for small-scale shrimp farmers in Indonesia.

Changes in rainfall patterns continue to affect pastoralism as practiced by the Maasai community in Kajiado County. The Maasai community is vulnerable to effects of the changing rainfall pat terns induced by climate variability. The community has tried to cope with these changes by altering livestock feeding practices but knowledge gaps exist as to whether these characteristic responses adequately respond to the problem posed by changing rainf all patterns. Thus, this study established how changes in rainfall patterns influence livestock feeding practices of the Maasai community in Kajiado County. A sample size of 136 household heads was used for the study. Results indicated that most of the res pondents had noticed changes in rainfall patterns ( 99%), 58.09 % reported that

Diarrheal diseases remain a significant contributor to the global burden of disease. Climate change may increase their incidence by altering the epidemiology of waterborne pathogens through changes in rainfall patterns. To assess potential impacts of future changes in rainfall patterns, we analyzed 33,927 cases of diarrhea across all Ministry of Health clinical facilities in Esmeraldas Province, Ecuador, for a 24-month period from 2013 to 2014, using mixed-effects Poisson regression. We assessed the association between the incidence of diarrheal diseases and heavy rainfall events (HREs) and antecedent rainfall conditions. In rural areas, we found no significant associations between HREs and incidence. In urban areas, dry antecedent conditions were associated with higher incidence than wet conditions. In addition, HREs with dry antecedent conditions were associated with elevated incidence by up to 1.35 (incidence rate ratio, 95% CI: 1.14-1.60) times compared with similar conditions without HREs. These patterns may be driven by accumulation of fecal contamination during dry periods, followed by a flushing effect during HREs. This phenomenon is more important in dense urban environments with more impervious surfaces. These findings suggest that projected increases in rainfall variability and HREs may increase diarrhea burden in urban regions, which are rapidly expanding globally.

Spiders were once thought to have limited color production palettes, and even to lack melanin – one of the most ubiquitous biological pigments. Recent discoveries upend that view and show that the color production mechanisms in spiders are as elaborate as some of the more classically colorful groups of animals, such as birds, butterflies, and beetles. Here we summarize how colors are produced by spiders, identify gaps in our knowledge, show how researchers investigating color in different groups of animals can learn from each other, and suggest future opportunities for spider color research. Our understanding of color production mechanisms in other colorful groups of animals can be used as guidelines for discovering existing mechanisms previously unknown in spiders and vice versa. For example, spider species with colors potentially produced by the same kind of photonic structures previously described in white beetles, and in the blue/green scales of fishes and lizards are suggested here. In addition, novel principles first found in spiders that modify the iridescence of structural colors via the interaction of structural features across different length scales (i.e., micro-nano) may also be found in other colorful groups in the future. This review summarizes the state-of-the-art understanding regarding the proximate color production mechanisms in spiders, suggests a few future research directions that are likely to be fruitful, and facilitates the advancements in related fields, including the ecology, evolution, and functions of spider coloration.

Summary Sexual dichromatism (SD) often reflects intense sexual selection on males. It has been hypothesized that sexual selection should favour the elaboration of those male colours that honestly signal quality and that such colours should therefore show higher SD. Costliness of colours is expected to vary according to their production mechanism (pigment type, feather microstructure and combinations thereof). Carotenoid‐based colours, due to their dietary origin and competing functions of carotenoid pigments, are the best documented costly colours, while endogenous pigments and structural colours are expected to be less costly. However, how SD varies with colour‐producing mechanism has not been systematically addressed. Here, we test the link between SD and mechanisms of colour production across nearly all Australian passerines (n = 302) and parrots (n = 48), using reflectance spectrometry and visual models. We quantified SD [chromatic (hue and saturation) and achromatic (light to dark)] for individual plumage patches as well as for the whole plumage. We then compared whether these SD estimates vary for plumage produced by different mechanisms of colour production. Not unexpectedly, individual plumage patches were most sexually dichromatic when males and females have different mechanisms of colour production. In most cases however, both sexes share the same mechanism. Among these, red carotenoid‐based plumage in passerines showed the highest SD, while in passerines as well as in parrots, melanin‐based plumage and white plumage have the lowest levels of SD. Average SD within species is weakly predicted by the proportion of the plumage produced by different mechanisms. This effect is strongest for red carotenoids, but equally so for males and females. In contrast, effects of structural and pheomelanin‐based colours are different between sexes, highlighting the links between high SD and the evolution of different mechanisms of colour production in males and females. While our analysis showed that colours based on red carotenoids have higher levels of SD, the differences were small, and most mechanisms of colour production were able to produce a similar range of SD. These results do not support the hypothesis that sexual selection should preferentially lead to the elaboration of some types of colours over others. A lay summary is available for this article.

Animal body coloration is a complex trait resulting from the interplay of multiple mechanisms. While many studies address the functions of animal coloration, the mechanisms of colour production still remain unknown in most taxa. Here we compare reflectance spectra, cellular, ultra- and nano-structure of colour-producing elements, and pigment types in two freshwater turtles with contrasting courtship behaviour, Trachemys scripta and Pseudemys concinna. The two species differ in the distribution of pigment cell-types and in pigment diversity. We found xanthophores, melanocytes, abundant iridophores and dermal collagen fibres in stripes of both species. The yellow chin and forelimb stripes of both P. concinna and T. scripta contain xanthophores and iridophores, but the post-orbital regions of the two species differ in cell-type distribution. The yellow post-orbital region of P. concinna contains both xanthophores and iridophores, while T. scripta has only xanthophores in the yellow-red postorbital/zygomatic regions. Moreover, in both species, the xanthophores colouring the yellow-red skin contain carotenoids, pterins and riboflavin, but T. scripta has a higher diversity of pigments than P. concinna. Trachemys s. elegans is sexually dichromatic. Differences in the distribution of pigment cell types across body regions in the two species may be related to visual signalling but do not match predictions based on courtship position. Our results demonstrate that archelosaurs share some colour production mechanisms with amphibians and lepidosaurs (i.e. vertical layering/stacking of different pigment cell types and interplay of carotenoids and pterins), but also employ novel mechanisms (i.e. nano-organization of dermal collagen) shared with mammals.

Response of a Mediterranean semiarid community to changing patterns of water supply

The North Sumatera rainfall area is classified as equatorial type, which characterized by two peaks of maximum rainfall for each year and distribute evenly through the year with maximum 1 dry month. However, the occurrence of rainfall below normal in the period of January-April in 2014-2016 shows that there has been a change in rainfall patterns that can be caused by climate change. This paper aims to identify changes in rainfall patterns on the east coast of North Sumatera spatially and temporally. Over 16 years (1999–2014) monthly and annual rainfall data series in 74 locations along east coast of North Sumatera are selected for identifying the rainfall pattern change. The data was taken from private rain gauge and North Sumatra Agency for Meteorology, Climatology, and Geophysics (BMKG), which located along the east coast of North Sumatera. The observation on annual rainfall shows changes in rainfall patterns in the study sites would occur every 5-7 years. The occurrence of La Nina and El Nino also give a part on the change of annual rainfall pattern.

Mountain landscapes have dynamic climates that, together with tectonic processes, influence their topographic evolution. Spatial and temporal variations in rainfall are ubiquitous in these settings as orographic precipitation patterns evolve with climate change and topography. Despite important implications such changes have for river incision, their influence is understudied. Here, we investigate how changes in rainfall pattern should affect both the steady state form and transient evolution of river profiles at the catchment scale using the stream power model. We find that spatially varied rainfall patterns can complicate steady state relationships between mean rainfall, channel steepness and fluvial relief, depending on where rainfall is concentrated in catchments, and lead to unexpected transient behavior if they are neglected. Specifically, changes in rainfall pattern cause multi‐stage transient responses that differ from responses to uniform changes in rainfall. Disparate responses by rivers that experience different rainfall conditions, particularly trunk and tributary rivers, are also an important factor in understanding catchment‐wide responses to climate change. Accounting for such disparities in sampling strategies and topographic analyses may, therefore, be vital for detecting and quantifying climate's role in landscape evolution. Lastly, we show how explicitly accounting for rainfall patterns in channel steepness indices, and thus spatial variations in erosional efficiency, may advance understanding of landscape sensitivity to climate. These results have important implications for detecting transient responses to changes in rainfall pattern (and more broadly climate), interpretation of morphometrics in steady state and transient landscapes, and quantifying the sensitivity of landscapes and erosion rates to climate.

The subject area of climate change is vast, but the changing pattern of rainfall is a topic within this field that deserves urgent and systematic attention since it affects the availability of freshwater, food production and the occurrence of water related disasters triggered by extreme events. The detection of trends in rainfall is essential for the assessment of the impacts of climate variability and change on the water resources of a region. In June 2013, several days of extremely heavy rain caused devastating floods in the region, resulting in more than 5000 people missing and presumed dead. The present study aims to determine trends in the annual, seasonal, and monthly rainfall over Uttarakhand State. Long-term (1901–2013) gridded daily rainfall data at 0.25° grid have been used. Daily rainfall data at ten grid center locations (five each in Garhwal and Kumaon divisions) in the vicinity of Haridwar, Tehri, Uttarkashi, Rudraprayag, Joshimath, Almora, Bageshwar, Munsiyari, Pithoragarh, and Rudrapur have been processed and analyzed for a period of 113 years (1901–2013). Historical trends in daily rainfall have been examined using parametric (regression analysis) and non-parametric (Mann–Kendall (MK) statistics). On the basis of regression and MK test, rising and falling trend in rainfall and anomalies at various stations have been analyzed. The result shows that many of these variables demonstrate statistically significant changes occurred in last eleven decades. Statistically significant increasing trends of annual as well as monsoon rainfall have been observed at Haridwar, Rudraprayag, Joshimath, Almora, and Munsiyari whereas statistically significant decreasing trends of monthly rainfall (August, September, and October) have been observed at Uttarkashi and Tehri stations.