High resolution tracking of adult horseshoe crabs Limulus polyphemus in a New Hampshire estuary using fixed array ultrasonic telemetry

While several studies have documented the large-scale,seasonal movements of horseshoe crabs,little is known abouttheir fine-scale,daily movement patterns.In this study we used a fixed array ultrasonic telemetry system to track the movementsof 12 male and 16 female horseshoe crabs in the Great Bay estuary,New Hampshire.Data were obtained during the mating season,as well as during the remainder of the summer and fall,in the years 2005-2008.During the mating season animals were often,but not always,active during the high tides when they were approaching and leaving the spawning beaches.On average,bothmales and females approached mating beaches during 33% of the high tides they experienced and they most often made the transitionfrom being inactive to active during the last two hours of an incoming tide.From April-October horseshoe crabs were significantlymore active during high tide periods vs low tide periods,with no clear preference for diurnal vs nocturnal activity.Afterthe mating season ended horseshoe crabs continued to move into shallower water at high tide and then return to deeper water atlow tide.Observations by SCUBA divers suggest that during these excursions into the mudflats horseshoe crabs were digging pitsin the sediment while foraging for food.Thus,the tidal rhythm of activity that has been so well documented during the matingseason probably persists into the fall,and primarily involves foraging

Seasonal movements of American horseshoe crabs Limulus polyphemus in the Great Bay Estuary,New Hampshire (USA)

The goal of this study was to determine the year round movement patterns of American horseshoe crabs,Limuluspolyphemus,in the Great Bay Estuary,New Hampshire (USA) by using acoustic telemetry to track the movements of 37 adultLimulus,for periods ranging from 2 to 31 months.During the winter (December-March) horseshoe crabs moved very little.In thespring,when water temperatures exceeded 11℃,horseshoe crabs moved at least 1 km further up into the estuary to shallowersubtidal areas about a month prior to spawning.The mean distance traveled during spring migrations was 2.6 ± 0.5 (n=20) km upthe estuary.Mating occurred in May and June and during these months animals spent most of their time in shallow subtidal areasadjacent to mating beaches.In the summer (July-August),animals moved 1.5 ± 0.5 (n=26) km down the estuary,towards theocean,and ranged widely,using extensive portions of the estuary.In the fall (September-November) movement was more limited(0.5 ± 0.5 km;n = 24) while animals settled into wintering locations,where they remained until spring.The mean annual linearrange for all animals was 4.5 ± 0.3 km (n =35) and the maximum distance traveled by an individual horseshoe crab within oneyear was 9.2 km.There was no evidence that any of the horseshoe crabs tracked during this study left the

Intensive use of an intertidal mudflat by foraging adult American horseshoe crabs Limulus polyphemus in the Great Bay estuary, New Hampshire

Although concerns about harvesting levels of the American Horseshoe Crab,Limulus polyphemus have prompted increasedresearch into its ecology,current understanding of the species' foraging ecology is mostly limited to mid-Atlantic populations.This study elucidates the spatial and temporal pattern of Limulus foraging on an intertidal mudflat of a northern New Englandestuary.A novel survey method was used to monitor Limulus foraging activity without disturbing the sediment.A fixed50 m×2 m transect was monitored with monthly surveys of the number of Limulus feeding pits from June to October 2009,Mayand June 2010.Snorkelling surveys were also carried out to observe individual behavior and examine the spatial scale of activityof individual animals.Results showed frequent and intensive use of the mudflat by foraging Limulus.Limulus were actively foragingwithin the survey area during all months surveyed.Foraging patterns exhibited a seasonal pattern with activity levels peakingin August 2009 and increased significantly towards the end of the study in June 2010.It was also shown that Limulus intertidalforaging persisted and peaked after the spring breeding season.Observations of foraging Limulus revealed that individualpredators dig multiple pits within a single high tide,with little disturbance to the sediment in between.In addition to altering theperception of Limulus as a subtidal predator outside of the breeding season,findings from this study suggests a segregation ofspawning and feeding habitats,thus underscoring the need to consider a wider range of critical habitats in the management ofLimulus

What diameter?What height?Influence of measures of average tree size on area-based allometric volume relationships

Volume is an important attribute used in many forest management decisions.Data from 83 fixed-area plots located in central New Brunswick,Canada,are used to examine how different measures of stand-level diameter and height influence volume prediction using a stand-level variant of Honer's(1967)volume equation.When density was included in the models(Volume=f(Diameter,Height,Density))choice of diameter measure was more important than choice of height measure.When density was not included(Volume=f(Diameter,Height)),the opposite was true.For models with density included,moment-based estimators of stand diameter and height performed better than all other measures.For models without density,largest tree estimators of stand diameter and height performed better than other measures.The overall best equation used quadratic mean diameter,Lorey's height,and density(root mean square error=5.26 m^3·ha^(-1);1.9%relative error).The best equation without density used mean diameter of the largest trees needed to calculate a stand density index of 400 and the mean height of the tallest 400 trees per ha(root mean square error=32.08 m^(3)·ha^(-1);11.8%relative error).The results of this study have some important implications for height subsampling and LiDAR-derived forest inventory analyses.

Catatonia:A deep dive into its unfathomable depths

This editorial addresses catatonia,a complex neuropsychiatric syndrome characterised by a spectrum of psychomotor disturbances.The editorial seeks to clarify the ambiguous aspects of catatonia,integrating recent research findings,including global studies and diagnostic advancements.It discusses catatonia’s clinical manifestations,prevalence,and associated psychiatric and medical conditions,with particular emphasis on its frequent co-occurrence with schizophrenia and mood disorders.The prevalence of catatonia,which varies across psychiatric populations,is illustrated by a significant study conducted in Nelson Mandela Bay,South Africa.This study provides valuable insights into the effectiveness of the Bush-Francis Screening Instrument compared to the Diagnostic and Statistical Manual 5 criteria in diagnosing catatonia.The editorial evaluates treatment approaches,primarily focusing on benzodiazepines and electroconvulsive therapy,and discusses emerging therapeutic strategies.It underscores the importance of robust diagnostic frameworks and early intervention in managing catatonia,as recommended by the latest evidence-based consensus guideline.Furthermore,it suggests future research directions,particularly in exploring the neurobiological and genetic factors of catatonia,to enhance our understanding and improve treatment outcomes.This editorial succinctly aims to demystify catatonia and provide valuable insights for clinicians and researchers in mental health care.

Alternative expressions for stand diameter in complex forests

Quadratic mean diameter is the most frequently reported descriptor of the diameter distribution of forests.As such,it is often used as an indicator of forest stand structure,developmental stage,and ecological and economic potential.However,quadratic mean diameter can be heavily influenced by the presence or absence of large numbers of small stems in lower canopy strata,and it is also sensitive to left-truncation of the diameter distribution,making its interpretation across inventories with different protocols challenging.Here,we examine three alternative expressions of stand diameter:the arithmetic and quadratic mean diameter of the thickest 100 trees per hectare,and the basal area-weighted mean diameter.Using data from the United States Forest Inventory and Analysis program for New York and New England,these alternative expressions showed closer correlation with multiple stand structural variables than did quadratic mean diameter,including merchantable cubic and board foot volume per hectare,aboveground live tree carbon per hectare,and total number of live and dead standing trees greater than 40 cm diameter at breast height per hectare(previously proposed as an index of old-growth structure).Arithmetic and quadratic mean diameter of the thickest 100 trees per hectare showed nearly identical performance,and the strongest correlations across the board.We develop closed-form expressions for these variables when the diameter distribution is a Weibull,and illustrate their behavior relative to quadratic mean diameter for that situation.While the reasons for prevalence of quadratic mean diameter as an indicator remain valid,we suggest that these alternative measures should be more widely reported and analyzed to give a more informative depiction of stand structure and development in complex forests.

Isolation of Picocyanobacteria (Order Synechococcales) and Occurrence of the Cyanotoxin Anatoxin-A in a Shallow Mesotrophic Pond

We have verified the use of a serial filtration method to isolate picocyanobacteria for analysis. We used eDNA metabarcoding to confirm the picocyanobacteria as members of the Order Synechococcales, Genus Cyanobium, specifically Cyanobium 6307. Fluorometric analysis using accessory pigments phycocyanin and phycoerythrin described periods of excess biomass, where the net growth rate model confirmed these conditions. The total anatoxin-a concentrations in the picocyanobacterial sample ranged from 0.0074 - 6.41 μg·L-1 representing a 40-fold difference over the entire sampling season. Sampling frequency of every three days appeared to be an important factor in capturing these changes in anatoxin-a concentration. During a period of excess biomass, we were able to establish a linear correlation between cyanobacterial biomass and Anatoxin-a concentrations.

Isolation of Picocyanobacteria (Order Synechococcales) and Occurrence of Cyanotoxins (Anatoxin-a) in Saline Microhabitats at Martha’s Vineyard, MA

We have used serial filtration to isolate picocyanobacteria from brackish and marine microhabitats for analysis. We used 16s metabarcoding to confirm the picocyanobacteria as members of the Order Synechococcales, Genus Cyanobium 6307 (Upper Chilmark Pond) and differing abundances of Cyanobium 6307 and Synechococcus 9902 (Chilmark Pond, Edgartown Great Pond, Tisbury Great Pond and Tashmoo Pond). The proportion and composition of (pico)cyanobacteria in water samples were influenced by the salinity concentrations at various sites, as evidenced by fluorometry and 16s metabarcoding analysis. The cyanobacterial neurotoxin anatoxin-a was present in the picocyanobacterial samples from all studied sites. Additional analyses using fluorometry and 16s metabarcoding described members of the Order Nostocales, including a halotolerant population of Dolichospermum sp., Sphaerospermopsis spp. and Nodularia spp. in Upper Chilmark Pond. We were able to establish a positive linear correlation between cyanobacterial biomass (phycocyanin) and anatoxin-a concentrations using samples taken from Upper Chilmark Pond.

Eight decades of compositional change in a managed northern hardwood landscape

We analyzed over 8 decades of change in forest composition(represented by species proportion of basal area)and size class from more than 400 permanent plots located on the Bartlett Experimental Forest in the White Mountains of New Hampshire.These data represent one of the longest-term landscape-scale records of forest change based on permanent plots in North America.We analyzed the plots based on elevation class,land type indicating assumed successional direction(grouped into coniferous and deciduous),and inventory period within managed and unmanaged portions of the forest.An ongoing shift from small-to large-diameter stems is clear across all species,in response to the overall aging of the forest following exploitative harvesting in the 19th century.Major compositional changes include a continuing decline in shade-intolerant species(paper birch and aspen),along with the mid-tolerant yellow birch.An increase in red maple abundance through the early 1990s has leveled off or reversed.Among shade-tolerant species,increases in beech and red spruce were largely consistent with assumed land type on unmanaged plots,but heavy marking against diseased beech on managed plots restricted increase of that species.Sugar maple declined in abundance except where silvicultural intervention helped maintain it.By contrast,eastern hemlock showed a continuing expansion at all elevations below 600 m.The data continue to show little or no evidence of upward migration of species,despite evidence of recent regional change in climate.However,the BEF is poised for substantial changes when emerald ash borer and hemlock woolly adelgid,both of which are known to infest nearby areas,do arrive.

Determining the Charge-to-Mass Ratio of the Electron

The aim of this lab was to determine an experimental value for the charge-to-mass ratio e/me of the electron. In order to do this, an assembly consisting of Helmholtz coils and a helium-filled fine beam tube containing an electron gun was used. Electrons were accelerated from rest by the electron gun at a voltage of 201.3 V kept constant across trials. When the accelerated electrons collided with the helium atoms in the fine beam tube, the helium atoms entered an excited state and released energy as light. Since the Helmholtz coils put the electrons into centripetal motion, this resulted in a circular beam of light, the radius of which was measured by taking a picture and using photo analysis. This procedure was used to test currents through the Helmholtz coils ranging from 1.3 A to 1.7 A in increments of 0.1 A. Using a linearization of these data, the experimental value for the charge-to-mass ratio of the electron was found to be 1.850 × 1011 C/kg, bounded between 1.440 × 1011 C/kg and 2.465 × 1011 C/kg. This range of values includes the accepted value of 1.759 × 1011 C/kg, and yields a percent error of 5.17%. The rather low percent error is a testament to the accuracy of this procedure. During this experiment, the orientation of the ambient magnetic field due to the Earth at the center of the apparatus was not considered. In the future, it would be worthwhile to repeat this procedure, taking care to position the Helmholtz coils in such a way to negate the effects of the Earth’s magnetic field on the centripetal motion of electrons.

The Local Acceleration Due to Gravity as Determined with a Cart and Track

The aim of this lab is to determine an experimental value for the local acceleration due to gravity. In order to do this, a cart was released down a track and allowed to pass through two photogates recording the entrance and exit times of the cart. These times along with the length of a light blocking strip on the cart, were used to calculate the acceleration of the cart down the track at various angles, and through linearization, the experimental value for the local acceleration due to gravity was determined to be 10.027 ± 0.312 m/s2. This value has a percent error of only 2.2% from the accepted value of 9.8 m/s2, which proves that this method of determining local acceleration due to gravity can be effective and accurate. Additionally, this experimental value shows how similar the approximation is to the accepted value.

东北三省耕地土壤有机碳储量变化的模拟研究

利用农业生态系统生物地球化学模型(DNDC)方法,在GIS区域数据库支持下运行模型,研究了东北三省地区土壤有机碳储量状况,及其在现行农田管理措施下的变化特征。结果表明,以1998年为例,东北三省耕地土壤有机碳(SOC)储量(0-30cm土层)约为124 348万t,黑龙江、吉林和辽宁省分别占58.4％、25.5％和16.1％;在目前的农作制度下土壤有机碳库处于严重的负平衡,每年净丢失有机碳3122万t,黑龙江、吉林和辽宁省分别占59.3％、25.9％和14.8％;单位面积耕地SOC年减少量高达2.05 t·ha-1,黑龙江、吉林耕地SOC丢失最严重。增加秸秆还田比例,提倡免耕和人畜粪便还田,增施有机肥都有助于土壤有机碳的积累和有效地保持土壤有机碳平衡。

鄱阳湖农业区多熟种植时空格局特征遥感分析

农业土地利用活动是人类作用于地球系统最为直接的扰动因素,其变化会因改变生态系统过程与格局以及生态系统资源有效性而对生态系统功能在局地到全球尺度都产生重要的影响。中国南方普遍实施的多熟种植制度是高强度土地利用的重要特征之一,在中国传统的三熟农业区之一——江西省鄱阳湖区域,以农户为管理单元的农业种植制度由于受到洪水风险、经济效益及农业政策的调节,其时空格局动态也因此更加复杂。以分布在鄱阳湖平原的农田为研究区,结合多时相MODIS影像表达的作物生长规律和农业物候观测记录,检测并分析农业多熟种植的时空格局特征。研究结果表明空间分辨率500m、8d合成的MODIS/EVI时间序列数据能够定量表达出农业种植的多熟制特征,可以应用于区域农业多熟种植制度时空分析,研究区种植制度时空格局的形成是农户对气候、社会经济及粮食安全状况响应及适应的结果。在空间和时间上清晰地认识农业多熟种植的特征,将会对掌握高强度土地利用的过程和特点,模拟与评估土地利用对粮食安全及生态环境安全的影响有重要的意义。

农田土壤有机碳含量对作物产量影响的模拟研究

【目的】探求土壤有机碳含量对作物产量的影响,以期为保障国家粮食安全和耕地持续利用与管理提供决策依据。【方法】利用农田生态系统生物地球化学模型DNDC,针对中国东北、华北、西北、中南、华东和西南6个典型农业区域,每个区域选择各自典型的种植模式和现行的农田管理措施,在各自特定的土壤和气候条件下,输入并运行模型,模拟考察在其它投入条件不变的情况下,改变土壤有机碳本底值对作物产量的影响。【结果】当土壤有机碳含量(SOC)增加1g C.kg-1,东北地区玉米产量可增加176kg·hm-2;华北地区夏玉米与冬小麦轮作,产量可增加约454kg·hm-2;西北地区春玉米产量约可增加328kg·hm-2;中南地区单季水稻产量可增加约185kg·hm-2;华东地区双季稻产量可增加约266kg·hm-2;西南地区水稻与冬小麦轮作产量可增加约229kg·hm-2。【结论】在其它投入既定的条件下,全国各地区均存在通过提高耕地土壤有机碳含量来增加作物产量的潜力。保持较高水平的土壤有机碳含量对节本增效具有十分明显的作用。

中国农田土壤N_2O排放通量分布格局研究

中国作为世界上一个重要农业大国 ,对全球大气中 N2 O浓度的影响正在引起人们的普遍关注。该研究采用针对农业土壤痕量气体排放估算建立的、基于 N2 O的产生、传输和消耗机理的反硝化分解 (DNDC)模型 ,在建立了有关中国气候、农业土壤和农业生产的分县数据库基础上 ,估计了我国各县农业土壤 N2 O的排放通量 ,发现我国农田土壤 N2 O排放通量有较明显的地区差异 ,西北地区较低 ,东南地区较高。还发现无论温度升高 ,还是施肥量变化 ,对我国农田土壤 N2 O排放通量的影响 ,都存在区域差异 ,表现为东南地区的变化幅度较西北地区大 。

田间管理措施对土壤有机碳含量影响的模拟研究

利用农业生态系统生物地球化学模型(DNDC),选择6个典型的种植模式点,在特定的土壤和气候条件下运行模型,考察在其它投入条件不变的情况下,改变田间管理措施(秸秆还田、增施有机肥、改变化肥施用等)对土壤有机碳(SOC)含量影响的长期效应。研究结果表明,在众多的管理措施中,增加秸秆还田比例的固碳效应在众多的农田管理措施中体现最突出,以基本管理措施20年后有机碳含量为对照,当秸秆还田率增加到80%时,齐齐哈尔、平凉和芷江地区增加的SOC含量都在C 3 000 kg/hm2以上,北京郊区、江宁和盐亭地区每公顷则可以增加C10 000 kg以上。化肥增加SOC含量是通过增加作物还田残茬来实现的,与基本措施相比,除了华北和华东地区增施化肥使SOC含量显著增加外,其它地区均不明显。化肥施用量为本底值的50%配合秸秆还田率50%和化肥施用量为本底值的50%增施有机肥C 1 000 kg/hm2的两项措施,在各个地区都表现出比基本管理措施能存储更多的碳素,因此,在我国现在措施下,减少化肥的同时增加秸秆还田比例和增施有机肥是既增加土壤有机碳含量又减少化肥污染的"双赢"措施。

近200a来珠穆朗玛峰北坡远东绒布冰芯气候记录

１９９７年 ５月中美联合珠穆朗玛峰地区绒布冰川考察期间，在远东绒布冰川海拔 ６ ５００ ｍ的北 支冰流粒雪盆内钻取到一支４１ｍ长冰芯．通过数年层法并根据β活化度的参照年（１９５４年和 １９６３ 年），对远东绒布冰芯实施定年，冰芯底部为 １８１４年，冰芯年平均净积累量为 ２２４ ｍｍ（冰当 量）．根据远东绒布冰芯 （δ１８Ｏ的变化，重建了珠穆朗玛峰北坡地区近 ２００ ａ气候变化，发现有 ５次冷 期和５次暖期，且总趋势为变暖，这与本世纪北半球气候变暖的趋势相一致．远东绒布冰芯气候记 录同古里雅冰芯比较，两者的冷暖波动较为一致，说明青藏高原西北部和南部地区的气候变化具有 共性．但是，远东绒布冰芯中δ１８Ｏ的变化在短时间尺度上与降水量变化存在某些反相关性，这种关 系并未影响到δ１８Ｏ反映气温的长期变化趋势．

珠穆朗玛峰地区近200年冰芯草酸根记录及其环境意义

1997年5月中美联合珠峰地区绒布冰川考察期间，在远东绒布冰川海拔6500m北支冰流粒雪盆内钻取到一支41m长冰芯.该冰芯定年至1814年．远东绒布冰芯中近200年来草酸根浓度变化与Ca2+和NH4浓度变化一致性较差，表明草酸根的来源有别于大气尘埃和生物来源．草酸根浓度与冰芯中气温指标δ18O的变化具有一致性,说明气温是影响大气中草酸根浓度变化的因素之一，但非主导因素.远东绒布冰芯记录的20世纪以来草酸根浓度的迅速升高反映了人类工业活动对大气环境的污染．20世纪50~80年代，大气中受人类工业活动污染的草酸根浓度约为19世纪自然本底值的3倍，其中60年代人类活动排放的草酸盐类对大气的污染最为严重.

北方农牧交错带耕地土壤有机碳储量变化模拟研究——以内蒙古自治区为例

运用农业生态系统生物地球化学模型 (DNDC) ,估算北方农牧交错带内蒙古自治区耕地土壤C储量并研究其平衡状况结果表明 ,该区耕地 0～ 3 0cm土层土壤有机碳储量约为 4662 2 .6万t ,目前土壤有机碳库处于严重负平衡 ,年净损失有机碳 13 3 5万t。指出干旱半干旱农牧交错区应推行免耕。

耕作措施对陕西耕作土壤碳储量的影响模拟

鉴于农业生态系统土壤有机碳(SOC)平衡对中国农业可持续发展的重要性,文章以陕西农业生态系统为对象,整合农业生物地球化学模型(DNDC)与陕西农业地理信息系统数据库,利用陕西地区气象和作物资料,对陕西省2000年作物生长发育和土壤碳循环进行了模型模拟,实例探讨了耕作管理对土壤碳储量的影响,并由此评价生物地球化学模型在气候变化、土壤性质及农业耕作管理措施对土壤碳含量影响方面的预测能力。敏感性分析表明土壤性状,尤其是初始有机碳含量是影响模型区域尺度模拟的最主要敏感因素。区域模拟使用灵敏系数分析法,分别采用敏感因子的最大、最小值驱动模型在每一模拟单元内的运算,以产生一个土壤有机碳变化的范围值,土壤有机碳变化的真实值应以较大机率包含在这一范围内。分析模拟结果可以得出3点结论:1)2000年陕西耕作土壤总有机碳储量约为103TgC,是一个大气CO2源,向大气释放碳0.5TgC;2)提高作物秸秆还田率是提高陕西农田碳库储量的有效可行措施,将作物秸秆还田率从当前的15%提高到50%或90%会使陕西农田土壤从大气CO2源转变为汇,每年分别增加土壤有机碳库储量0.7TgC或2.1TgC;3)施用有机农肥(500kg/hm2)也会增加土壤碳输入,从而提高土壤碳储量,使陕西农田系统转变为较弱的碳(C)源,每年可多固定0.2TgC。