Direct evidence of limited dispersal of the reef fish Parapercis colias (Pinguipedidae) within a marine reserve and adjacent fished areas

1. Spillover of organisms from marine reserves may augment adjacent areas, and is often cited as an important reason for the establishment of marine protected areas. Spillover is dependent on residence or limited dispersal of organisms resulting in an increase in their abundance and size within a marine reserve. 2. To investigate movement (i.e. spillover versus residence) we tagged and released 90 blue cod Parapercis colias (Pinguipedidae) at each of four sites, two in and two adjacent to Long Island–Kokomohua Marine Reserve, Marlborough Sounds, New Zealand. The study was done 4–5 years after establishment of the no‐take reserve. 3. Abundances of blue cod were similar in and out of the marine reserve, but mean estimated size was 4 cm larger in the reserve than at fished sites. 4. Fewer tag resights were made in the reserve than at fished sites, and tagged blue cod were resighted at greater depths in the reserve than at fished sites. 5. Most resights (75% for fished sites, 73% for reserve sites) were made within 100 m of the tagging sites, and the number of resights declined through time, though tagged individuals were resighted up to 31 months after tagging. 6. The lower number of tag resights at reserve sites, despite the lack of extraction, is consistent with some blue cod at reserve sites moving longer distances than those at fished sites. 7. The greater size of individuals in the reserve and limited dispersal of a proportion of the population show that survivorship of blue cod is increased within marine reserves. 8. Computer simulations based on measured dispersals indicate that even marine reserves of a few hundred metres long‐shore extent have the potential to supplement fished populations nearby. 9. These data provide direct evidence of limited dispersal of the most common edible reef fish in the Marlborough Sounds. Blue cod will grow to larger sizes in marine reserves and via spillover will become available to fishers in adjacent areas of contiguous coast. Copyright © 2000 John Wiley & Sons, Ltd.     

甘薯茎腐病传播侵染途径与田间发病流行因子探讨

为探明小番薯主产区浙江临安等地甘薯茎腐病的发生流行规律以及灾发影响因子,以不同品种的番薯为试材,通过2016—2019年连续4年的室内研究、田间试验和调查观察。结果表明：主栽品种的高感病性是该病近年来发生流行的主要因素之一;该病原菌可在病残体和薯块中越冬,成为翌年的初侵染来源,且土壤中病原菌数量要达到10⁴~10⁵ cfu/cm³才能引起薯苗发病并显症;高温高湿条件可加速病害的发展;种薯与薯苗带病调运是该病远距离扩散传播的主要途径;使用脱毒无病苗、轮作、深沟高畦栽培措施可有效减轻病害的发生,为今后该病害的综合治理研究提供了参考依据。     

Distribution of aquatic plants in the Northern Vosges rivers: implications for biomonitoring and conservation

• 1. The continual confusion over the definition of the term ‘trophic status’ has led to ambiguous demonstrations of the influence of alkalinity versus inorganic N and P on aquatic plant distribution.
• 2. Data from the Northern Vosges rivers (sandstone geology) were reinvestigated to test whether it was possible to separate the effect of (i) spatial isolation from surface water chemistry, and (ii) alkalinity from inorganic N and P on aquatic macrophyte distribution.
• 3. Alkalinity and pH exerted the strongest influence on plant distribution, soluble reactive phosphorus (SRP) and pCO₂ being subordinate. The effect of spatial isolation between catchments was not significant, which may indicate that aquatic plants dispersed well over the area. The effect of longitudinal connectivity on species distribution was strong, although largely confounded by the effects of water chemistry and possibly other physical factors not recorded. The partial effect of SRP (after removing the effect of pH or alkalinity) was still significant. However this was not the case for NH₄.
• 4. The floristic composition was more likely to indicate the role played by alkalinity than inorganic P, with inorganic N being further subordinate. However, the causality of the significant relationships needs to be investigated further. This study questioned the validity of current macrophyte biomonitoring tools striving to indicate the concentrations of inorganic N and P.
• 5. More work is needed to quantify the role of connected and isolated aquatic habitats in the region, in order to understand how to maintain the species pool and to ensure that recolonization rates compensate for the losses due to disturbances. It is not clear how the vegetation would respond to inorganic P enrichment (or control), based on the individual species response observed here, and river P uptake studies from other rivers. Future monitoring should also include measurements of physical degradation.

Copyright © 2007 John Wiley & Sons, Ltd.     

稻作区灌溉水流传播的杂草种子与稻田土壤杂草种子库的关系

选择典型稻作区,对灌溉水流传播的杂草种子的种类和数量进行取样调查,并与田埂、灌溉水渠周围生境、下茬麦田的杂草群落及稻田土壤杂草种子库进行比较分析,以研究自然条件下灌溉水流传播的杂草种子与土壤杂草种子库及其他生境杂草群落间的相互关系。 有14科21种杂草种子随灌溉水流输入稻田,这些杂草种子主要隶属禾本科、报春花科、藜科、蓼科等。土壤杂草种子库中共检出19科41种杂草种子,含有所有其他生境中杂草的种子。灌溉水流传播的杂草种子与田埂上、灌溉水渠周围生境、下茬麦田杂草群落及稻田土壤种子库的杂草群落间相似性较高,Sorensen指数均在0.5以上。     

Modelling the dispersal of larval Japanese sardine, Sardinops melanostictus, by the Kuroshio Current in 1993 and 1994

Acoustic Doppler current profiler (ADCP) data collected during routine monitoring surveys of the distribution and abundance of Japanese sardine larvae ( Sardinops melanostictus ) off the Pacific coast of Japan in February 1993 and 1994 were used to construct stationary average flowfields for three levels in the upper 100 m in each year. No large-scale meanders in the path of the Kuroshio Current were present in either year, but the axis of the current was closer to the coast in 1993 than in 1994. The flowfields were used to drive a particle-tracking model representing the dispersal of sardine eggs and larvae. Particles were released in accordance with the observed distribution of eggs, and their positions tracked for up to 40 days. In 1993, the model indicated that ≈ 50% of the egg production was carried north-eastwards out of the survey area into the area of the NW Pacific referred to as the Kuroshio Extension Zone. In contrast, only 5% of the egg production was exported to the Extension Zone in 1994, the remainder being retained in Japanese coastal waters. The consequences of the different dispersal patterns are discussed in relation to subsequent recruitment to the sardine stock. Based on commercial catch data, survival of the 1993 year class was 15% of that for the 1994 class. Hence, the results indicate that export of larvae to the Kuroshio Extension cannot in itself lead to successful recruitment.     

胡桃楸种实第一扩散阶段分布特征

在黑龙江帽儿山老爷岭生态站,采取观察和收集法对生长在不同坡度上胡桃楸种实的第一扩散阶段的分布规律进行研究得出:胡桃楸种实较大且沉,主要靠重力作用下落,种实落地后基本集中在冠幅范围内,随着距离的增加,种实数量先增加后减少;胡桃楸种实在不同立地条件下以及不同时段的分布规律不同,坡度较缓处,种实数量最大值出现在2~3m处,坡度较陡情况下,种实数量最大值出现在5~6m处或不明显;在落种高峰期下落的种实,其数量随着距离变化的分布规律显著,落种初期、末期种实数量与距离之间基本不相关,种实在地表的分布具有方向性,下坡方向的种实数量多于上坡方向。     

Spontaneous gene flow and population structure in wild and cultivated chicory, Cichorium intybus L.

Spontaneous gene flow between wild and cultivated chicory, Cichorium intybus L., may have implications for the genetic structure and evolution of populations and varieties. One aspect of this crop-wild gene flow is the dispersal of transgenes from genetically modified varieties, e.g. gene flow from GM chicory to natural chicory could have unwanted consequences. With the purpose to identify and quantify crop-wild gene flow in chicory, we analysed introgression in 19 wild chicory populations and 16 accessions of chicory varieties and landraces distributed across Northern, Central and Mediterranean Europe. The analysis used 281 AFLP markers and 75 SSAP markers giving a total of 356 polymorphic markers. Results from model based assignments with the program STRUCTURE indicated many incidents of recent gene flow. Gene flow was observed both between cultivars and wild populations, between landraces and wild populations, between different wild populations as well as between cultivars. Population structure visualized by distance-based clustering showed a North–South geographical structuring of the wild populations, and a general grouping of the cultivars corresponding to known origin. The results indicated, however, that the structuring between the two groups of wild and cultivated types was weak. As crop and wild recipients are genetically close and genes are transferred between the two types rather frequently, focus on mitigating crop-wild gene flow should be increased, before transgenic varieties are cultivated openly.     

Terrain controls on depressional soil distribution in a hummocky morainal landscape

In hummocky morainal landscapes, soil distribution in well-drained landscape positions tends to follow a consistent pattern. Soils in depressions, however, are more difficult to predict reliably. This study had two objectives: (1) to determine the parent material and landscape properties controlling the formation of the different depressional soils; and (2) to use these controls to identify quantitative, terrain-based predictors of soil type in depressions. Only two terrain attributes, specific dispersal area (SDA) and elevation relative to open water bodies, were required to distinguish three main soil groups: Gley Recharge, Non-gley Recharge, and Discharge soils.

Specific dispersal area is the downslope area draining flow from a given grid cell. Gley Recharge soils occur primarily at points with SDA of less than 2 m² m⁻¹, regardless of elevation within a given site, because most of the runoff flowing to a point with very low SDA values will pond or infiltrate vertically rather than flow downslope. Non-gley Recharge soils and Discharge soils both occur at points with SDA of greater than 2 m² m⁻¹. The majority of the Non-gley Recharge soils occur above 5-m elevation relative to an open water body and the majority of the Discharge soils occur below 5-m elevation relative to an open water body, reflecting the importance of solute cycling in the development of discharge conditions. Buried and depositional soils could not be predicted from current terrain attributes because their profile characteristics were derived from the paleosurface.     

日本五针松感染松材线虫病的检测与扩散风险分析

【目的】从日本五针松(Pinus parviflora)栽培圃地调查松褐天牛(Monochumus alternatus),并取样镜检松材线虫(Bursaphelenchus xylophilus),揭示日本五针松感染松材线虫病的可能性和扩散风险,为开展检疫提供理论依据。【方法】在日本五针松圃地采集枯死或濒死的日本五针松植株,采用分离镜检法检测枯死或濒死日本五针松木质部的线虫种类;剖木检查天牛危害,观察留在日本五针松松枝上的补充营养伤口,同时鉴定天牛幼虫特征,解剖检验羽化的天牛成虫携带LⅣ状态。【结果】在枯死或濒死6株日本五针松枝条样本中有3株样本分离到松材线虫或拟松材线虫,检出率为50%,其中1个样本检出纯松材线虫,1个样本检出纯拟松材线虫,1个样本为松材线虫和拟松材线虫混合寄生,检出率各为33%。侵入枝干的天牛幼虫为松褐天牛幼虫,该幼虫能在日本五针松上顺利羽化为成虫,并携带松材线虫L_(Ⅳ)型耐久型幼虫。【结论】日本五针松能被携带松材线虫的松褐天牛危害并感染松材线虫病,应加强检疫管理,杜绝通过人为调运苗木扩散传播松材线虫病。