Determining spatial feed distribution in sea cage aquaculture using an aerial camera platform

Within this paper we describe an unmanned aerial vehicle (UAV) based method to estimate the spatial feed pellet distribution in salmon fish-cages and exploit it within a case study to determine the radial pellet distribution for different rotor spreaders and blower configurations. Compared to previously used methods, capturing pellets thrown from a rotary feed spreader in rows of Styrofoam boxes, the UAV based method is simpler and faster to setup and allows to cover a larger portion of the sea cage surface area. We compare results obtained with the Styrofoam box method with results we obtained by an automatic analysis of aerial videos taken by the UAV during feeding experiments. The employed method helps to gain insight into the spatial feed pellet distribution in full-scale salmon fish-cages where the feeding pipe and actual fixation of the spreader may influence the dynamic behaviour of the feeding system. This can also be seen as a step towards a continuous measuring of the feed pellet distribution, particularly in view of possible future feeding systems that may allow to adapt the feed pellet distribution to the actual fish distribution.     

Fine‐scale habitat partitioning of Chilean and Peale's dolphins and their overlap with aquaculture

1. Predictive species distribution models (SDMs) have become powerful tools to determine habitat use patterns of mobile marine predators and their spatial overlap with potentially impacting anthropogenic activities.
2. This study used SDMs to investigate fine‐scale habitat use patterns of two poorly known and broadly sympatric coastal delphinids, Chilean dolphins (Cephalorhynchus eutropia) and Peale's dolphins (Lagenorhynchus australis), and their spatial interactions with intense aquaculture farming activities in the Chiloé archipelago, southern Chile.
3. A long‐term dataset (2002–2012) of boat‐based dolphin sightings and concurrently in situ collected environmental and anthropogenic variables was analysed using binomial Generalized Additive Models to investigate ecological drivers of each species' fine‐scale distribution and to predict dolphin occurrence spatially.
4. Chilean dolphins preferred shallow (<30 m deep), turbid waters, close to shore (<500 m) and river mouths which often placed them in sheltered bays and channels used intensively by shellfish farms. Peale's dolphins were also found in shallow waters but occurred over a wider range of conditions along more open or exposed coastlines. Both species had to navigate extensive salmon and shellfish farming sites to transit between areas of important habitat.
5. Sightings and predicted occurrence maps showed a clear pattern of spatial habitat partitioning between species, which remained stable across the 11 year study period. The identification of important habitat for Chilean dolphins warrants the consideration of spatially explicit conservation measures to limit the potential effects of overlapping salmon and shellfish farming.
6. The observed differences in ecological plasticity of the two sympatric species should be considered when evaluating and mitigating the effects of environmental change and ongoing anthropogenic pressures on their nearshore habitat. The estimated species–environment relationships could also be used to predict where dolphin habitat and anthropogenic activities are most likely to overlap in other parts of the species' ranges.

     

微咸水膜下滴灌对土壤水盐分布及加工番茄产量的影响

为探明微咸水膜下滴灌对土壤水盐分布及加工番茄生长和产量的影响,通过大田小区试验,设置灌水矿化度和灌水定额两个因素,其中3个灌溉水矿化度水平分别为S1:1 g·L~(-1)、S2:3 g·L~(-1)和S3:5 g·L~(-1),3个灌水定额分别为W1:305 m~3·hm~(-2)、W2:458 m~3·hm~(-2)和W3:611 m~3·hm~(-2),来进一步寻求适宜本地区加工番茄生长的微咸水膜下滴灌灌溉制度。结果表明:覆膜微咸水滴灌条件下土壤含水量垂直方向的变化趋势表现为0～20 cm土层随深度增加含水量逐渐降低、20～100 cm土层随深度增加含水量逐渐增大、60～100 cm范围内土层剖面含水量最大的分布规律;土壤含盐量随着灌水矿化度的增大而增加,且随着灌水量的增加土壤盐分逐渐向水平距滴灌带35 cm处聚集。灌水矿化度超过3 g·L~(-1)时加工番茄株高、茎粗均受到一定程度的抑制作用,但对产量影响不大。本文通过试验得出:灌水定额为611 m~3·hm~(-2)、矿化度为1 g·L~(-1)处理为本地区最佳微咸水膜下滴灌处理,加工番茄生长健壮且产量最高,达到127 613.2 kg·hm~(-2);同时认为,在我国淡水资源比较缺乏的新疆地区可以考虑采用灌水定额458 m~3·hm~(-2)和灌水矿化度3～5 g·L~(-1)的微咸水对盐分中等敏感的加工番茄进行灌溉。     

社群丰容对圈养小熊猫区域分配的影响

为探索社群丰容对重庆动物园圈养小熊猫行为区域分配的影响,2014年1月—2015年2月,用目标动物取样法对比观察春季、夏季、秋季、冬季社群丰容前后圈养小熊猫区域分配。结果表明:社群丰容增加了小熊猫对栖架、树上的利用,减少了内室和裸露地面和近游客区域的利用。树上利用的最大占比值在夏季,丰容增加了11.1%;栖架的利用最大占比值在春季,丰容增加了2.8%;冬季对内室的利用占比值最高,丰容后,其利用占比减少了8.4%,从而相应增加了小熊猫户外停留时间;丰容后,小熊猫对裸露地面的最大利用占比值减少了3.7%,近游客区域最大占比值减少了5.6%。小熊猫对六大区域的最高利用占比,丰容前后没有变化,最高为树上,最少为裸露地面。     

不同氮素水平下双季稻株型与冠层内光截获特征研究

本文旨在阐明双季稻株型与冠层内光合有效辐射截获的时空分布特征。选用4个不同株型早、晚稻品种,设置4个不同施氮水平,系统观测其植株形态和冠层内光合有效辐射截获率(IPAR)的时空分布状况。结果表明,施氮水平对早、晚稻株高、穗长、叶长和叶基角均有显著影响,均表现为随施氮水平的增加而增大;早、晚稻孕穗期的分层叶面积指数(LAI)和向上累积LAI大于抽穗后12 d,分层LAI呈冠层中部大于上部和下部的分布特征,最大分层LAI出现在0.58相对高度处;冠层上中部分层LAI和向上累积LAI随施氮水平的增加而增大;向上累积LAI随相对高度呈S型曲线分布,可用Logistic方程定量描述(R~2 0.99);早、晚稻孕穗期的冠层IPAR大于抽穗后12 d,且随施氮水平的增加而增大,其日变化表现为正午较小,早晚较大;株型紧凑的早、晚稻品种,冠层IPAR低;冠层IPAR与向下累积LAI之间的关系可用方程IPAR=a (1-e~(-b×LAI))定量描述(R~2 0.88);冠层内IPAR的三维空间分布表现为冠层上中部水平面上IPAR较低,光斑变化大,冠层下部水平面上IPAR较高,光斑变化较平缓,同一冠层高度水平面上的IPAR呈不均匀分布。研究结果可为双季稻高产栽培及理想株型的优化设计提供支撑。     

藏青杨虫瘿的空间分布格局

为明确蚜虫在西藏工布自然保护区藏青杨(Populus szechuanica var.tibetica)叶片上的危害特征及其产生虫瘿的分布特点,基于野外调查数据,应用扩散系数(C)、Morisita指数(I)、Cassie指标(Ca)、平均拥挤度(M*)、Lloyd聚块性指标、负二项参数(K)、Iwao回归分析法、Taylor幂指数法对该区藏青杨叶片上虫瘿空间分布格局进行研究。结果表明,藏青杨叶片左上虫瘿出现率为25.36%、左下为24.30%、右上为24.98%、右下为25.36%,叶片左边为49.66%、右边为50.34%;藏青杨不同方向叶片上虫瘿出现的比率均在25%左右。藏青杨叶片上虫瘿主要以3~7个聚集的形式存在。虫瘿出现频次(y)与虫瘿数量级别(x)的拟合曲线为y=-2.150 3x~2+23.159x-7.309 1(R~2=0.818 4)。6级虫瘿数量最多,占总虫瘿数的22.15%。由虫瘿空间分布参数可知,藏青杨叶片上虫瘿空间分布呈聚集型,但虫瘿聚集强度不大。总体上虫瘿个体群大小随虫瘿密度的增加而增大,个体群指数L值平均大小为7.20。经拟合,虫瘿空间分布格局Iwao M*-M回归模型为M*=1.059 9m+0.523 4(R~2=0.993 9),Taylor模型为log S2=1.043 4logm+0.043 7(R~2=0.996 4),两模型均判定为聚集分布。综上,虫瘿在藏青杨不同方位的出现率相近,但在叶片上均呈聚集分布,虫瘿的聚集除与环境因素有关外,也与其生物学特性相关。     

基于地统计学的土壤重金属分布与污染风险评价

在野外调查取样和室内分析获得大量土壤重金属含量数据和空间数据的基础上,利用经典统计学和普通克里格法(OK)对采样区域土壤重金属含量的空间变异性进行了分析,并利用指示克里格法(IK)和多变量指示克里格法(MVIK)绘制了各项重金属元素污染风险和土壤污染综合风险概率图。结果表明:岩溶地貌区土壤重金属As、Cd、Cr、Cu、Pb、Hg、Ni和Zn的含量显著高于非岩溶地貌区,各项重金属元素之间具有显著的相关性,说明它们存在很大的同源性和复合关系;受岩性、成土母质等内在因素的影响,各项重金属元素(除Cu元素外)都具有强烈的空间变异性,重金属元素含量高值主要分布在东南部和北部的岩溶地貌区,低值主要分布在西南部的非岩溶地貌区;采样区域存在As、Cd、Cu、Hg、Ni和Zn等重金属污染风险,其风险概率分别为0.326、0.805、0.185、0.192、0.267和0.270,土壤重金属污染综合风险概率为0.335。     

钙处理桃果肉钙离子的分布及其与果实品质形成的关系

为探讨钙元素对桃果实品质、耐贮藏性的影响,确定最佳的叶面喷施钙元素的浓度,研究了喷施钙后,桃果肉组织中钙元素的分布特征、叶片叶绿素的含量以及对果实可溶性固形物含量(SSC)、大小、硬度和耐贮藏性的影响。结果表明,果肉中Ca2 的含量随着喷施钙元素浓度的提高而增加,当喷施CaCl2浓度为0.5%时叶绿素的含量最大,当喷施CaCl2浓度为1%时,SSC、果实大小和果肉硬度达到最大值；当喷施CaCl2浓度为2%时,放置3天后果实硬度最大。本研究确立了最佳的喷施浓度,为深入研究果实钙离子浓度梯度在果实品质形成方面的作用提供了依据。     

湘西北长果安息香种群数量与分布格局

对湖南石门壶瓶山景关门、桑植龙潭坪茅垭村样地的长果安息香(Changiostyrax raxdolichocarpa)种群数量和分布格局进行调查和分析。结果表明：长果安息香种群的年龄结构呈衰退型，个体数量主要集中在小树(IV龄段)，幼龄级株数和老龄级株数匮乏；长果安息香种群在进入生理死亡年龄前有2个死亡高峰，第1个峰值产生于幼树(II、III龄段)，主要原因是种内和种间竞争(主要是光照)，第2个峰值产生于中树长成大树阶段(V、VI龄段)，除种内、种间对环境的竞争外，生长地土层浅薄、大树倒伏及人为砍伐亦加剧了该峰值的产生；种群整体呈聚集分布类型，小树向中树、大树变化过程表现出聚集分布向随机分布转变，导致长果安息香濒危的主要原因是种子萌发率极低、种群竞争能力较差以及人为干扰等。     

Short and long‐term distribution with depth of soil organic carbon and nutrients under traditional and conservation tillage in a Mediterranean environment (southwest Spain)

The impacts of tillage and cropping sequences on soil organic matter and nutrients have been frequently reported to affect the uppermost soil layers, but there is little published information concerning effects at greater depth. This article reports results on the distribution of soil organic carbon (SOC), active carbon (AC), N, Olsen‐P and extractable K within 100 cm in short (4 yr) and long (16 yr) term experiments under different tillage systems. Short (TT₄) and long (TT₁₆) traditional tillage are compared with conservation tillage, reduced (RT₁₆) and non‐tillage (NT₄). The results show more accumulation of SOC in the near‐surface under RT₁₆ and NT₄ in both experiments compared with traditional tillage. Moreover, greater C content occurs to 40 cm depth in the long‐term experiment. The results demonstrate the importance of time on C accumulation, not only in near‐surface layers but also at greater depths. Active C is an indicator of the increase in soil quality in the long‐term experiment. This trend is only apparent for the first 10 cm in the short‐term experiment. Patterns in N, Olsen‐P and extractable K are similar to that of SOC. However, only extractable K is significantly greater in soil under conservation tillage (RT₁₆ and NT₄) after short and long periods. Potassium availability is a good indicator of the changes caused by tillage. Our results indicate that studies of soils at depth could be very useful in long‐term experiments to demonstrate the effect of conservation tillage on C and nutrient distribution.