Ontogenetic habitat use and seasonal activity of Nile crocodiles (Crocodylus niloticus) in the Lake Albert delta,East Africa

Crocodiles play important roles in many ecosystems, but their populations worldwide are threatened by human exploitation and habitat destruction. We studied ontogenetic changes in habitat use and seasonal activity patterns in a population of Nile crocodiles (Crocodylus niloticus) inhabiting the Lake Albert Delta Wetland System, a Ramsar Site of international importance in Murchison Falls National Park of western Uganda. A total of 186 crocodile observations were made from monthly surveys of five transects during October 2017 to September 2018. Crocodiles exhibited a marginally bi-modal seasonal pattern, with the fewest observations from July to August and October to November, and the highest observations from January to February and April to May. Crocodiles were most frequently encountered along the north shore of the delta, especially on riverbanks with woody vegetation, followed by Cyperus papyrus-Vossia dominated habitats, while crocodiles were infrequently observed on islands and muddy banks. Habitat niche breadth was narrowest in hatchlings and widest in sub-adults, with juveniles and large adults exhibiting intermediate values. Overlap in habitat resource use across size classes was generally high, with the lowest overlap between hatchlings and juveniles, and the highest between large and sub-adult crocodiles. Our study on Nile crocodiles in the Lake Albert delta provides insights into habitat partitioning among different demographic segments of this population that can be utilized to improve its management in one of Africa’s Great Lakes by spatially and temporally focusing conservation efforts on the most used habitats and seasonal aggregations, respectively.     

Ethanol consumption in Brazil: Empirical facts based on persistence,seasonality and breaks

This paper investigates the consumption of sugar cane ethanol in Brazil for the time period from January 2000 to December 2012. We examine ethanol and gasoline consumption along with the price ratio series. Two important features of the data are analyzed, in particular, its degree of persistence and the seasonality. The results show that the two series of consumption are fractionally integrated with orders of integration smaller than 1 implying that shocks in the series will disappear in the long run. On the other hand, the price ratio series displays an order of integration higher than 1 implying lack of mean reversion behavior. This suggests that strong policy measures must be adopted on prices in the event of shocks since they do not recover by themselves in the long run.     

Book reviews

Seasonality and seasons of Estonian landscapes are analysed using selected natural and social indicators of urban and rural landscapes. Seasonality has a great influence on the ecological and visual features of landscapes; seasonal variability is especially great in temperate climate zones where relatively cold winters alternate with warm summers. The indicators that are suitable for describing the seasonality of landscapes are natural parameters such as air temperature, radiation regime, climatic seasons and snow cover, and social parameters of birthdays, alcohol consumption and state budget allocations. Because of the great seasonal differences in natural and socio-economic conditions, the differences between urban and rural landscapes having different seasonal rhythms are focused upon. One of the main differences is the change in lifestyle which is detected in the change in the seasonal variability of births. Seasonal differences between urban and rural landscapes are also confirmed by parameters of changing climate and some social indicators. The developing information society creates new jobs and a lifestyle that has its own seasonal rhythm. Periods of active work and social activity accumulate towards the deadlines preceding the Christmas and the summer period of vacations. A project-oriented information society has more flexibility to enjoy nature in rural landscapes during different seasons.     

The importance of the relationship between scale and process in understanding long-term DOC dynamics

Concentrations of dissolved organic carbon have increased in many, but not all, surface waters across acid impacted areas of Europe and North America over the last two decades. Over the last eight years several hypotheses have been put forward to explain these increases, but none are yet accepted universally. Research in this area appears to have reached a stalemate between those favouring declining atmospheric deposition, climate change or land management as the key driver of long-term DOC trends. While it is clear that many of these factors influence DOC dynamics in soil and stream waters, their effect varies over different temporal and spatial scales. We argue that regional differences in acid deposition loading may account for the apparent discrepancies between studies. DOC has shown strong monotonic increases in areas which have experienced strong downward trends in pollutant sulphur and/or seasalt deposition. Elsewhere climatic factors, that strongly influence seasonality, have also dominated inter-annual variability, and here long-term monotonic DOC trends are often difficult to detect. Furthermore, in areas receiving similar acid loadings, different catchment characteristics could have affected the site specific sensitivity to changes in acidity and therefore the magnitude of DOC release in response to changes in sulphur deposition. We suggest that confusion over these temporal and spatial scales of investigation has contributed unnecessarily to the disagreement over the main regional driver(s) of DOC trends, and that the data behind the majority of these studies is more compatible than is often conveyed.     

Seasonal variations in chemical composition and stable isotopes of farmed and wild Brazilian freshwater fish

This study examined variations in the Fulton condition factor, chemical composition, and stable isotopes of carbon and nitrogen in the Brazilian freshwater fish cachara (Pseudoplatystoma fasciatum), comparing farmed and wild fish in different seasons. Values for energy, protein, moisture, and Fulton’s condition factor were higher for farmed than for wild fish in the rainy season, indicating better nutritional quality; however, these differences were not observed in the dry season. Likewise, we found significant enhancement of δ¹⁵N in farmed fish in the rainy season but not in the dry season, whereas enhancement of δ¹³C was observed in both seasons. The combined measurement of δ¹³C and δ¹⁵N provided traceability under all conditions. Our findings show that stable isotope analysis of C and N can be used to trace cachara origin, and that seasonal variations need to be considered when applying chemical and isotopic authentication of fish and fish products.     

上海天然气市场和液化天然气的现状与展望

2009年,上海能源供应体系自从引入液化天然气以来,进口液化天然气对全市天然气供应总量和来源多元化做出了重要贡献。2013年,液化天然气消费在全市天然气消费总量中占比达50%,在天然气供应体系中发挥了越来越重要的作用。近年来,上海天然气市场发生了深刻变化,天然气需求增长放缓,与2013年之前十多年的两位数增长形成了鲜明对比。为了更好地理解市场的基本面,首先回顾了上海天然气消费的历史趋势,随后分析了影响需求增长的驱动因素和约束条件,以判断未来天然气需求的趋势和液化天然气在市场中扮演的角色,认为天然气需求增长的潜力主要在民用及商业领域。结合分析可能的供应选择,其结论是未来液化天然气将继续作为上海天然气供应体系的主力气源,同时提供市场急需的灵活性以保障高峰时段的用气需求。     

基于GIMMS、VGT和MODIS的中国东部植被指数对比分析

GIMMS NDVI、VGT NDVI和MODIS NDVI/EVI是目前在植被变化有关研究中经常使用的植被遥感数据,它们之间的差异也得到了广泛关注。然而,在分析这些数据之间的差异时,较少有研究注意到植被本身固有的季节循环可能夸大了各数据间的相关关系。应用2000~2006年GIMMS NDVI、VGT NDVI、MODIS NDVI/EVI等不同植被遥感数据,对比了基于这些数据集的中国东部植被年际变化的差异,探讨了植被季节循环对不同遥感数据之间相关性的影响。结果表明:由不同遥感数据提取的植被年际变化特征具有明显的一致性,然而,植被本身固有的季节循环特征掩盖了不同数据集的差异。季节循环去除前,各数据集之间具有显著的相关性;季节循环去除后,各数据集的相关性明显降低,但不同数据集在北部区域依然具有较好的一致性,其差异主要出现在南部区域,差异最明显的是GIMMS与MODIS数据,二者在淮河以南的区域几乎不存在显著相关。     

Seasonality: Nature,People's Preferences and Urban Planning in Oulunsalo,Finland

Seasonal changes are particularly strong in northern Europe. Daylight, temperature, flora, fauna and landscape change from day to day. We discuss how seasonality exists in nature, is felt by people and is reflected in urban planning. The case study regards Oulunsalo municipality with a population of 9,000 at the northern most Baltic Sea coast in Finland. In 2003 the mean temperature of the coldest month in Oulunsalo was ?16.4 and the warmest +19.5 centigrade. The longest day was 22 hours 3 minutes and the shortest 3 hours and 35 minutes. A survey among the adult Oulunsalo population shows that summer is the best season for the majority of people (72%)—more often for men (78%) than for women (66%). Almost everybody (96%) likes the change of seasons. Seasons and seasonal preferences should be considered more in urban planning processes and land-use plans.     

A comparison of benthic meiofaunal communities in the oldest European lake

The comparison of isolated stable habitats, that share major ecological parameters and organism groups, generates valuable knowledge about ecology and evolution. In this study we want to identify the most suitable habitat and organisms for comparisons. For this, we needed to study the effects of seasonality, habitat variability and diversity. Therefore, we studied the benthic meiofaunal communities in the sediment and hard substrates of Lake Ohrid’s littoral and profundal sediments as well as littoral rotifers collected monthly and seasonally between 2000 and 2010. Our results showed that, among the over two million meiobenthic organisms per square meter, nematodes dominated the profundal (mean proportion: 91%) and littoral (mean proportion: 87%) sediments; whereas, rotifers were the most abundant group in littoral periphyton (mean proportion: 64%). The community composition was very typical of each habitat-type, homogeneous in the profundal and more heterogenous in the littoral. Rotifer communities were only significantly less diverse and abundant in winter. Thus, a comparison of ancient lake nematodes living in the deep profundal is potentially quite valuable. However, littoral communities are less stable in terms of seasonality and heterogeneity.     

Generalized linear regression analysis of association of universal helmet laws with motorcyclist fatality rates

This study evaluates the association of universal helmet laws with U.S. motorcyclist fatality rates from 1993 through 2002 using climate measures as statistical controls for motorcycling activity via quasi-maximum likelihood generalized linear regression analyses. Results revealed that motorcyclist fatalities and injuries are strongly associated with normalized heating degree days and precipitation inches, and that universal helmet laws are associated with lower motorcyclist fatality rates when these climate measures, and their interaction, are statistically controlled. This study shows that climate measures have considerable promise as indirect measures (proxies) of motorcycling activity in generalized linear regression studies.