Seasonal Distribution Patterns Research Articles

Modeling Spatio-Temporal Variations in the Habitat Utilization of Swordtip Squid (Uroteuthis edulis) in the East China Sea and Southern Yellow Sea.

Accurately modeling the distribution of keystone species is of utmost importance to gain a comprehensive understanding of their complex ecological dynamics and to develop effective strategies for sustainable scientific management. In the coastal China ecosystem, the swordtip squid (Uroteuthis edulis) stands out as a keystone species with significant commercial and ecological value. Despite its importance, research on the ecological dynamics of this species remains limited and requires further investigation. To investigate the spatial and temporal variability in the distribution of U. edulis and identify the key environmental drivers in the East China Sea (ECS) and southern Yellow Sea across different seasons, we generated ensemble models using oceanographic variables and fishery-independent scientific survey data collected from 2016 to 2018. Our results revealed that U. edulis predominantly inhabited the central and southern regions of the ECS throughout the year. The primary environmental variables driving its distribution varied by season, with the sea surface temperature being the most important in spring, sea surface height in summer and autumn, and depth in winter. During summer and autumn, the suitable habitats of U. edulis were found to be largest and extended northwards towards the coastline. However, they migrated southwards to the waters near the edge of the ECS continental shelf with smaller suitable areas in the spring and winter. These results suggested that U. edulis exhibited season-specific habitat preferences and responded to changing environmental conditions throughout the year. The observed seasonal distribution patterns were likely influenced by the fluctuating mixture of waters (ocean currents) from different sources, with varying physical and chemical characteristics throughout the year. Our study provides baseline data for comprehending the population dynamics of U. edulis and highlights the significance of considering species' habitat preferences in a dynamic environment.

Effects of Vegetation Types and Seasonal Dynamics on the Diversity and Function of Soil Bacterial Communities in the Upper Reaches of the Heihe River

The process of interaction between the plant and soil microbial communities holds the key to understanding the biogeochemical cycle and preserving the stability of vegetation ecosystems. Owing to this significance, the primary goal of this research was to give a starting point and reference methods to restore local vegetation. The vegetation distribution in the mountainous area of the upper reaches of the Heihe River Basin had notable vertical zonality, which was characterized by five typical vegetation types, including cushion vegetation(CV), herbage meadow(HM), forest steppe(FS), mountainous steppe(MS), and desert grassland(DG). The organization and diversity of soil bacterial communities in various vegetation types were examined using high-throughput sequencing techniques in both the winter and summer seasons. Sampling sites were chosen in each of the five common vegetation types in turn. Additionally, based on the FAPROTAX database, the predicted functions of microbial communities were evaluated for different vegetation types and seasons. The redundancy analysis and structural equation model were also used to investigate the primary environmental elements and uncover the mechanisms affecting the soil bacterial populations. The findings revealed that:① the physical and chemical properties of soil differed significantly among vegetation types and seasons, and the property indices varied dissimilarly with depth. In particular, the soil water content(SWC) and nutrient content of total organic carbon(TOC) and total nitrogen(TN) were significantly higher in forest grassland(FS). ② The divergences of α-diversity indices among seasons(P<0.05) were greater than that of vegetation types(P>0.05). The Chao1 index measuring the abundance of the bacterial community was higher in winter. According to the Shannon index, the species of the bacterial community were dispersed in a "W" shape in the summer and a "hump" form in the winter with altitude. ③ The predominant phyla of the bacterial community, composed of Acidobacteria, Proteobacteria, and Actinobacteria, did not significantly differ from one another. However, the organization of the bacterial community presented a significant variation seasonally at the genus level. ④ The primary functions of the soil bacterial population, which largely consisted of chemoheterotrophy, nitrification, and aerobic ammonia oxidation, were not significantly different among vegetation types and seasons. ⑤ The key factors affecting soil bacterial communities at the genus level varied significantly among seasons, with soil temperature(ST), total organic carbon(TOC), and pH in winter and soil water content(SWC), carbon-nitrogen ratio(C/N), and pH in summer. ⑥ Synergized by interrelated environmental factors, soil physical and chemical features exerted a more direct impact on the diversity and functionality of bacterial communities compared with vegetation types, including significantly changing the abundance of Acidobacteria and Bacteroidetes, as well as the role of nitrification and ammonia oxidation. Hence, improving the carbon and nitrogen contents in soil nutrients would help to enhance the diversity and function of bacterial communities. The findings of this study provided a model for determining the mechanism of regional vegetation degradation and preserving the stability of alpine ecosystems in this area by revealing the seasonal distribution pattern of bacterial communities and the key biological processes beneath the typical vertical vegetation band in the upper reaches of the Heihe River.

Seasonal distribution patterns of Scomberomorus commerson in the Taiwan Strait in relation to oceanographic conditions: An ensemble modeling approach

The decline in the stock of the narrow-barred Spanish mackerel in the Taiwan Strait has sparked interest in conservation efforts. To optimize conservation and restoration efforts, it is crucial to understand their habitat preference in response to changing environments. In this study, ensemble modeling was used to investigate the seasonal distribution patterns of Spanish mackerel. Winter was identified as the most productive season, followed by fall; productivity was the lowest in summer. Five single-algorithm models were developed, and on the basis of their performance, four were selected for inclusion in an ensemble species distribution model. The spatial distribution of Spanish mackerel was primarily along the latitudinal range 23°–25°N in spring and summer. However, in fall and winter, the geographical range increased toward the southern region. The findings of this study will contribute to the understanding of this specific species and the approach used in this study may be applicable to other fisheries stocks also.

The first baleen whale marine protected area proposed for Bryde's whales in the Beibu Gulf, China

AbstractThe establishment of marine protected areas (MPAs) for cetaceans is an important strategy to mitigate human disturbance and protect biodiversity. Despite abundant cetacean species, there are only a few MPAs dedicated to cetacean conservation in China, all of which are for inshore dolphins. Bryde's whales, the only nearshore baleen whale population in mainland China, are conflicting with intensive human activities, yet an effective conservation strategy is lacking. This study used species distribution models to analyze distribution patterns and suitable habitats of Bryde's whales in the Beibu Gulf and proposes the first baleen whale MPA in China. Our results showed Bryde's whales have a seasonal distribution pattern in the Beibu Gulf, and that the waters around Weizhou Island and the southeastern coast of Vietnam were their core habitats. The seasonal nighttime light data indicated a negative relationship between the number of ship lights and Bryde's whale sightings and suggest that Bryde's whales might be threatened by fisheries. We proposed an MPA based on the results, suggesting that the waters within 20 km around Weizhou Island should be declared a protected area. Furthermore, we recommend that anthropogenic activities in the waters around Weizhou Island are better managed to reduce negative impacts on marine life.

Prevalence and quantitative assessment of foodborne viruses on the imported mussels in Polish market

The aim of this study was an assessment of the prevalence of human enteric viruses such as norovirus (NoV) and hepatitis A and E virus (HAV, HEV) in mussels sold on the Polish market. In addition, the presence of human (hAdV) and swine (pAdV) adenoviruses as indicators of faecal contamination of shellfish was also studied. In total, 246 shellfish samples representing 41 batches of blue and Mediterranean mussels were purchased from Polish seafood wholesalers. Shellfish were processed according to the method in ISO 15216-2:2019 followed by isolation of viral nucleic acids using NucliSens®Magnetic Extraction Reagents (bioMérieux). For virus detection several duplex real-time PCR protocols with incorporated internal amplification controls (IAC) were used. The presence of human enteric viruses was shown in 42 shellfish samples (17.1%). The most frequently detected were NoV (41 samples; 16.7%) followed by HEV (1 sample; 0.4%). None of the samples was positive for HAV, hAdV or pAdV. 15 shellfish batches (36.6%) were virus positive. By the use of Bayesian inference, a true seasonal and country related virus prevalence in shellfish was estimated. NoV GI was more frequently detected in Dutch mussels (18.9%; 95% CI: 6.7%–34.0%), while NoV GII was more frequent in Danish mussels (17.1%; 95% CI: 5.8%–32.5%). However significant differences in virus prevalence in individual and shellfish batches between producing countries were not shown. A seasonal virus distribution pattern in shellfish samples was observed. Lower level of NoV contamination was found in mussels harvested during spring-summer (0.0%–1.3%, 95% CI: 0.1%–4.8%) compared to the fall-winter season (13.0%–20.7%, 95% CI: 6.1%–31.2%). For shellfish batches, a similar seasonal correlation was only observed for NoV GII. The monitoring of marketed shellfish would be an essential tool allowing a reduction of the number of viral food-borne outbreaks.

Determining the spatiotemporal variation, sources, and ecological processes of antibiotic resistance genes in a typical lake of the middle reaches of the Yangtze River

Antibiotic resistance genes (ARGs) are emerging environmental pollutants, influenced by complex regulatory factors. River-lake systems act as natural reservoirs for ARGs and provide an ideal model for studying their regulatory mechanisms. This study employed high-throughput quantitative PCR, high-throughput sequencing, correlation analyses, and model predictions to investigate the dynamics of ARGs and their influencing factors in Liangzi Lake, located in the mid-reaches of the Yangtze River. The research specifically centered on three environmental components: lake water, sediment, and river water. Results indicated that the ARGs from eight major antibiotic classes, displaying distinct seasonal distribution patterns. In comparison to the sediment, the water phase demonstrated a higher diversity of ARGs, with the highest level of ARGs sharing observed between lake and river waters (approximately 83.7 %). Furthermore, seasonal variations significantly influenced the distributions of both ARGs and bacterial communities. The diversity of ARGs was highest during the summer and autumn, and specific bacterial species exhibited robust correlations with ARGs (including matA/mel, aac (6′)-Ib-03, and blaROB). It is worth noting that environmental attributes and bacterial diversity had the most substantial impact on the dynamic changes in ARGs. Lastly, source tracking analysis pinpointed that sediment as the primary source of ARGs in lake water, constituting 45 % to 48 % of the total ARGs. Our study provides a comprehensive analysis of ARGs and their influencing factors in the river-lake system of the middle reaches of the Yangtze River, with Liangzi Lake as a representative case.

Seasonal incidence and distribution pattern of insect pest infesting onion ecosystem in the red lateritic zone of West Bengal

Seasonal incidence and distribution pattern of insect pest infesting onion ecosystem in the red lateritic zone of West Bengal

Distribution Patterns of Pathogens Causing Lower Respiratory Tract Infection Based on Metagenomic Next-Generation Sequencing.

Lower Respiratory Tract Infection (LRTI) is a leading cause of morbidity and mortality worldwide. In this study, the distribution patterns of causative pathogens in LRTI were evaluated within a city-level hospital by combining conventional microbiological tests (CMT) with metagenomic next-generation sequencing (mNGS). This retrospective cohort study involved 160 patients suspected of having LRTI in a single center. Specimens, including bronchoalveolar lavage fluid (BALF), blood, tissue, sputum, and pus were utilized to identify pathogens. The seasonal prevalence of pathogens and co-pathogens involved in multiple infections was analyzed. A total of 137 patients with 156 samples were included in this study. Pseudomonas aeruginosa, Corynebacterium striatum, Klebsiella pneumoniae, Candida, and human herpesvirus were the top prevalent pathogens. We observed seasonal dynamic variation in the top prevalent bacteria (Pseudomonas aeruginosa and Klebsiella pneumoniae) and herpesvirus (Epstein-Barr virus and Human herpesvirus-7). The majority of patients had single bacterial infections, followed by instances of bacterial-viral co-infections, as well as mixed infections involving bacteria, fungi, and viruses. Notably, the spectrum of co-infecting pathogens was broader among the elderly population, and positive Spearman correlations were observed among these co-infecting pathogens. Co-infections were prevalent among patients with LRTI, and the pathogens displayed distinct seasonal distribution patterns. The findings underscored the significance of comprehending pathogen distribution and epidemic patterns, which can serve as a basis for early etiological identification.

Seasonality and risk factor analysis of respiratory syncytial virus infection in children in Taiwan-A retrospective study from 1995 to 2005.

Respiratory syncytial virus (RSV) is one of the important pathogens leading to acute respiratory tract infection in infants and young children. We aimed to investigate the seasonality of RSV infection in different parts of Taiwan and to delineate the risk factors for severe RSV infections. We collected RSV-infected patients' data by retrospective chart review. A total of 1740 RSV-infected children aged under 18 years were enrolled. The infection was acquired during hospitalization in 103 (7.1%) children, while none of them required ventilator support or needed intensive care before RSV infection. The need for intensive care or ventilator support was significantly associated with congenital heart disease (CHD), chronic lung disease, and neuromuscular diseases. Age <1 year and nosocomially acquired infection are also significant predictors for the need of intensive care. Only the presence of CHD, especially acyanotic CHD, was significantly associated with a fatal outcome. RSV infection occurs all year round. Monthly distribution of RSV infections in Northern Taiwan showed a bimodal pattern, with one peak from March to May, and another from August to October. The distribution in Southern Taiwan showed a single peak from April to July. The occurrence of RSV correlates positively with temperature and rain. The bimodal seasonal distribution pattern in Northern Taiwan may be a transitional pattern shifting from a single high winter peak in temperate areas to a wider summer peak in tropical areas. Continuous surveillance is needed to explore the possible effect of global warming on the seasonality of RSV infection.

Parasitic and Ecological Factors Associated with Transmission of Urogenital Schistosomiasis in Owena Reservoir Area, Ondo State, Nigeria

Human urogenital schistosomiasis caused by infection of the trematode worm Schistosoma hematobium is a major source of morbidity and mortality in Ondo State especially in Owena Reservoir Area, Ondo East Local Government Area, Ondo State, Nigeria. The aim of this study was to investigate: (i) the seasonal and spatial distribution, infection and cercariae shedding patterns of identified local Schistosoma intermediate snail host(s); (ii) to determine the influence of ecological factors on the identified intermediate snail species in the transmission of urogenital schistosomiasis along the Owena Reservoir and river courses. All the snails collected were placed in pre-labeled plastic containers and were transported to a Malacology Laboratory at Ile-Ife, Osun State, Nigeria. The snails were identified to species level, counted and recorded as number of snails, per site, per date. The snails were identified using standard identification keys. Examination of snails for Schistosoma infection was carried out by crushing method. Cercariae were identified to genus level. However, only snails shedding Schistosoma cercariae were recorded as infected. Each of the eight sites was sampled once monthly for twenty-four months. Eight stations (sites) of diverse ecological characteristics were selected along the Owena Reservoir and monitored for snails species’ diversity, distribution and infection patterns, physicochemical properties of H2O, macrophyte types and coverage in relation to the transmission of urogenital schistosomiasis. Seven snail species representing two sub-classes, three families and five genera were identified in Owena Reservoir Area. Bulinus globosus and Bulinus truncatus were the only established Schistosoma intermediate snail hosts in site 4 (KAJ 1) located in Kajola community. Out of the eight sites studied, site 4 in Kajola community had the highest infection rate while Embankment/Dam (site 8) had the least. Site 4 in Kajola community is therefore the major transmission site. All the snail species correlated positively with alkalinity conduction, negatively with air temperature. Bulinus globosus correlated significantly positive with Ludwiga erecta, Ludwiga decurrens, Commelina africana, and Berberis calamus (p&lt;0.05) but correlated significantly negative with Panicum maximus and Ervatomia hirta (p&gt;0.05). Bulinus truncatus correlated significantly positive with Aspillia africana, Ludwiga decurrens, Emilia occinina, and Crosus sativue (p&lt;0.05) but correlated significantly negative with Ludwiga erecta, Panicum maximus, and Commelina africana (p&gt;0.05). This study recommends environmental management and manipulation using water level regulations to render water contact sites environmentally unfriendly for both snail growth and human recreational activities during the period of high risk transmission since chemical control (the use of molluscicide) poses a risk to health, not only to the snail intermediate hosts but also to the inhabitants of the communities who commonly depend on reservoirs, streams, rivers, dams for their domestic water supply.

Seasonal distribution analysis of five lasiurine bat species: clues to migration patterns and behavior

Abstract Lasiurus is a bat genus recognised to have migratory species. However, little is known about the seasonal distribution for most of its species. We used spatial analysis of occurrence records and ecological niche modeling to evaluate the seasonal distributions of five species: Lasiurus borealis, Lasiurus frantzii, Lasiurus ega, Lasiurus xanthinus, and Lasiurus intermedius, to disentangle their seasonal distribution patterns. L. intermedius, L. xanthinus, and L. frantzii presented distinct seasonal patterns in the rate of occurrence records in different areas, which accumulate most records in the northern populations in summer. For L. borealis, we found seasonal variation throughout its entire distribution, with most records in summer and a progressive decline towards winter. In contrast, L. ega showed no seasonal changes in any region. In species with seasonal changes in their occurrences records, the projections of summer conditions did not predict their preferred winter conditions, suggesting these species occupy different ecological niches seasonally. We found seasonality in the northern areas of these species’ distributions, although we could not distinguish whether migration movements or torpor behaviors are the underlying cause. Conversely, we suggest that most central and southern populations of the five species do not exhibit seasonality and are year-round residents.

Seasonal shifts in diel vertical migrations by lake‐dwelling coastal cutthroat trout, Oncorhynchus clarkii clarkii, reflect thermal regimes and prey distributions

AbstractLakes provide important habitat for salmonids that may use them as a primary feeding area between periods of reproduction. The seasonal changes in vertical thermal structure in lakes can affect the distribution of salmonids on seasonal and diel time scales as they search for, consume, and digest prey that also exploits the water column's distribution of food, temperature and light. Our goal was to analyse the vertical distribution of wild, native coastal cutthroat trout (Oncorhynchus clarkii clarkii) in Lake Washington on daily and seasonal time scales. This lake is stratified in the summer and isothermal in winter, allowing us to compare vertical movements between periods with and without thermal structure in water 50 m deep. We predicted that trout would be deeper in the water column during stratified months and shallower during isothermal months, and shallower at night than in the day. Overall, the trout showed these patterns in the depths and temperatures they occupied, tending to be within or below the thermocline in the summer but not in the coolest water available, and closer to the surface when the lake was isothermal. The trout were also closer to the surface at night and deeper during the day. The vertical range of these diel movements shifted with the seasons–deepest in October, as the thermocline deepened and weakened, and shallowest in January when the lake was isothermal. These seasonal and diel vertical distribution patterns by the trout optimise metabolism for growth, and facilitate feeding on planktivorous fishes that also show seasonal and diel vertical distribution changes.

Spatial and seasonal patterns of cetacean species richness: A Bayesian approach

Research about community-wide patterns in cetaceans is challenging, so seasonal cycles and patterns of distribution are still poorly understood for many locations. In the present study, we proposed Bayesian Spatial General Linear Models (GLMs) to quantify and map cetacean species richness in southeastern Brazil's Santos Basin, considering environmental effects, effort, and seasonality. Systematic surveys were conducted in Santos Basin along zigzag-shaped transects over four years (November 2015 to April 2019), allowing consistent data collection over 40,000 km of effort through all seasons. A set of nine static physiographic data and eight dynamic environmental covariates were included in the models. A total of 371 sightings were recorded comprising 24 species. The best-fit model contained sea surface temperature, distance to 1000 m isobath, latitude, slope, and effort as covariates. We report that the cetacean species richness at Santos Basin is higher near the 1000 m isobath, in abrupt topographies, and off the northern portion; varies seasonally; is not spatially correlated; and is mainly affected by environmental predictors. These models and maps established a current characterization of cetacean species richness in these waters and have the potential to be applied in planning marine conservation, mainly in spatial prioritization programs.

Seasonal distribution and activity patterns of mesopredators and their prey in Southwest China

Abstract Mesopredators play an important role in shaping communities, especially when apex predators are no longer present. To persist, mesopredators must confront competition by developing different coexistence strategies. In this study, we used detection and activity data derived from remote cameras to investigate the seasonal coexistence of mesopredators and their interactions with prey in a region of Southwest China where apex predators have been extirpated. We found that Siberian weasels (Mustela sibirica) occupied the entire study area, whereas masked palm civets (Paguma larvata) were restricted to &amp;lt;1,900 m in fall, and expanded their ranges up by about 600 m in spring to likely prey on small mammals. We detected weasels at almost all locations where civets were present, but detection rates and activity patterns for both species suggested avoidance of larger-bodied civets by weasels. We found that weasels were active at all hours and overlapped with all prey both spatially and temporally, whereas civets were nocturnal and crepuscular, which only overlapped with murid rodents. Although we did not directly observe intraguild or predator–prey interactions, evidence suggested that masked palm civets and Siberian weasels seem to coexist due to different seasonal dietary preferences, hunting strategies, and activity patterns.

EDNA metabarcoding revealed the seasonal and spatial variation of phytoplankton functional groups in the Chai river and their relationship with environmental factors

Environmental DNA (eDNA) metabarcoding permits a new measurement to monitor biodiversity in aquatic ecosystems. This study utilized eDNA metabarcoding to examine the seasonal and spatial distribution of phytoplankton and their relationship with environmental factors in the Chai River, Kunming, China, in the dry, and wet seasons. The process detected 108 genera of phytoplankton, which were members of 11 phyla, 41 orders, and 60 families. Distinct differences in seasonal and spatial distribution patterns of phytoplankton diversity, including community structure, α-diversity, and representative functional groups, were observed. In the dry season, Pseudanabaena, Microcystis, and Synechococcus were the predominant genera in Cyanophyta, and Chlorophyta, Bacillariophyta and Euglenophyta were predominant in the eukaryotic phytoplankton. While in the wet season, Cylindrospermopsis, Microcystis, and Planktothrix predominated in the Cyanophyta, and Bacillariophyta, Chlorophyta and Xanthophyta predominated in the eukaryotic phytoplankton. Significant differences were shown by a principal coordinate analysis and PERMANOVA test among the upper, middle, and lower reaches of the phytoplankton communities except for the cyanobacterial community structure between the upper and lower reaches at the wet season (p > 0.05). The representative functional groups of phytoplankton varied from A, D, E, LM, L0, N, S1, MP, P, TB, TC, U, W0, W1, Xph, Y, and Z in the dry season to A, B, D, E, F, J, MP, LM, S1, SN, TC, P, W0, W1, X2, and Y in the wet season. Significant differences in the water temperature (WT), pH, chemical oxygen demand, oxygen consumed, nitrate nitrogen (NO3-N), and chlorophyll a were exhibited between the dry and wet seasons (p < 0.05). In the dry season, WT, NO3-N, and pH had a substantial influence on the functional groups LM, N, and L0 of the cyanobacteria. The EC and total nitrogen (TN) had a substantial influence on the functional groups A and Y of the eukaryotic phytoplankton. In the wet season, the electrical conductivity (EC), TN, and dissolvable total phosphorus (DTP) primarily affected the functional groups LM and S1, while EC, DPI, and soluble reactive phosphorus had a substantial influence on the functional groups A and Y. This study provides insights on the conservation of phytoplankton diversity and healthy management of the Chai River.

Seasonal abundance and distribution patterns of common bottlenose dolphins (Tursiops truncatus) near St. Joseph Bay, Florida, USA

Three unusual mortalities events involving bottlenose dolphins (Tursiops truncatus Montagu 1821) occurred along Florida’s northern Gulf of Mexico coast between 1999 and 2006. The causes of these events, in which over 300 bottlenose dolphins are known to have died, are still under investigation. The impact of these mortality events cannot be fully evaluated, because little prior information on bottlenose dolphin abundance and distribution patterns exist in this region. Thus, the goals of this study were to estimate seasonal abundance, develop site-fidelity indices, and describe distribution patterns of bottlenose dolphins in St. Joseph Bay, Gulf County, Florida, USA. This study site was chosen because it was impacted by all three unusual mortality events and was the geographic focus of the 2004 event. Mark-recapture photo-identification surveys were conducted across multiple seasons from February 2005 through July 2007. Site-fidelity indices were calculated for each identifiable dolphin based upon all photo-ID efforts undertaken in the area. Distribution patterns were investigated by short-term (12-94 days) radio-tracking of tagged individuals across seasons (April-July, n=9; July-October, n=15). Mark-recapture closed and robust abundance estimates, as well as site-fidelity indices suggest that St. Joseph Bay supports a resident community of 78-152 bottlenose dolphins. During spring and autumn, this region experiences an influx of dolphins, as demonstrated by closed and robust abundance estimates of 313-410 and 237-340, respectively. These results are supported by the distribution patterns of radio-tagged individuals. Individuals tagged in summer tended to stay within or near St. Joseph Bay, whereas two individuals tagged in spring ranged more than 40km from the study site. This study provides the first detailed examination of bottlenose dolphin abundance and distribution patterns for this region of the northern Gulf coast of Florida. These results suggest that unusual mortality events probably had, and will in the future have, seasonally variable effects on bottlenose dolphins in St. Joseph Bay. Future mortality events that occur during the summer and winter in St. Joseph Bay may predominantly affect resident individuals, while those that occur during the spring and autumn will probably affect both residents and seasonal visitors.

Abundance and distribution of marine mammals in nearshore waters off New Jersey, USA

Marine mammal abundance and distribution in New Jersey’s nearshore waters are not well known due to limited dedicated studies. The first yearround systematic surveys were conducted to determine the spatial/temporal distribution and estimate the abundance of marine mammals in this region prior to wind power development. Eight marine mammal species were observed: North Atlantic right whale (Eubalaena glacialis), humpback whale (Megaptera novaeangliae), minke whale (Balaenoptera acutorostrata), fin whale (Balaenoptera physalus), bottlenose dolphin (Tursiops truncatus), common dolphin (Delphinus delphis), harbour porpoise (Phocoena phocoena) and harbour seal (Phoca vitulina). Results indicate clear seasonal patterns in distribution and abundance. The fin whale, humpback whale and bottlenose dolphin were sighted during all seasons. The abundance of large whales in the study area was relatively low while the abundance of dolphin and porpoise species was high and largely seasonal. The bottlenose dolphin was the most abundant species; however, abundance was high only during spring and summer. Common dolphins and harbour porpoises were common in the study area during winter and spring. These baseline data will be used to assess potential environmental impacts of the construction and operation of offshore wind power facilities in this region.

Mapping reveals contrasting change patterns of rain-on-snow events in China during 2001–2018

Rain-on-snow (ROS) events can accelerate snow melting, which in turn leads to disasters such as floods, avalanches, and landslides. However, little is known about the characteristics of and changes in ROS events in China. In this study, the temporal and spatial variations of ROS days in China from 2001 to 2018 were investigated using the improved Moderate Resolution Imaging Spectroradiometer snow cover data, and China Meteorological Forcing Dataset. The results suggested that ROS days in China mainly occurred from November to June and were mainly distributed in northern Xinjiang (6.1 days/year), Qinghai-Tibet Plateau (2.8 days/year), northeast China (3.5 days/year), and east China (1.1 days/year). ROS days in each region have different seasonal distribution patterns. In the past 18 years, ROS days have shown a trend of increasing at higher latitudes and decreasing at lower latitudes in China, especially in northern Xinjiang and the Qinghai-Tibet Plateau. ROS days are decreasing below 3000 m in northern Xinjiang (-0.16 days/year) and below 4000 m in the Qinghai-Tibet Plateau (-0.21 days/year), which is explained by the decrease of snow days and rain days. ROS days are increasing at 3000–4000 m altitudes (0.15 days/year) in the Tianshan Mountains and 4000–5500 m altitudes (0.06 days/year) in the eastern Tibetan Mountains, mainly explained by more snowfall converted to rainfall. The ROS days along the Greater Khingan Mountains in Northeast China showed a decreasing trend (-0.12 days/year), and along the Changbai Mountains showed an increasing trend (0.07 days/year). The variation of snow cover days is the dominant factor. East China as a whole shows a decreasing trend (-0.1 days/year), explained by a decrease in snow cover time. In China, ROS days at low altitudes are negatively correlated with annual average temperature, and positively at high altitudes. The changes of ROS were also correlated with Arctic Oscillation and North Atlantic Oscillation. This study reveals the response of ROS to climate change in China, and provides an important reference for coping with the related disasters and changes caused by ROS events.

Avian and mammal diversities and their altitudinal and seasonal distribution patterns in Yarlung Zangbo Grand Canyon, China

Avian and mammal diversities and their altitudinal and seasonal distribution patterns in Yarlung Zangbo Grand Canyon, China

Identifying seasonal distribution patterns of fin whales across the Scotia Sea and the Antarctic Peninsula region using a novel approach combining habitat suitability models and ensemble learning methods

Following their near extirpation by industrial whaling of the 20thcentury, the population status of Southern Hemisphere fin whales (SHFW) remains unknown. Systematic surveys estimating fin whale abundance in the Southern Ocean are not yet available. Records of fin whale sightings have been collected by a variety of organisations over the past few decades, incorporating both opportunistic data and dedicated survey data. Together, these isolated data sets represent a potentially valuable source of information on the seasonality, distribution and abundance of SHFW. We compiled records across 40 years from the Antarctic Peninsula and Scotia Sea from multiple sources and used a novel approach combining ensemble learning and a maximum entropy model to estimate abundance and distribution of SHFW in this region. Our results show a seasonal distribution pattern with pronounced centres of distribution from January-March along the West Antarctic Peninsula. Our new approach allowed us to estimate abundance of SHFW for discrete areas from a mixed data set of mainly opportunistic presence only data.