镇江长江豚类省级自然保护区水域生态修复效果的监测与评价

自2006年以来,长江豚类极度濒危的生存状况得到广泛关注,在其自然保护区实施一系列生态修复工程,为镇江长江豚类省级自然保护区内的江豚提供良好的生存环境。于2015—2018年在和畅洲水域建设生态浮岛、人工鱼巢和放流底栖动物进行水域生态修复,对生态修复工程进行跟踪监测和效果评价。结果表明：生态浮岛的建设可提高区域内浮游植物和浮游动物的生物多样性和群落结构复杂程度;人工鱼巢对产黏性卵鱼类具有一定增殖效果,增殖种类主要为鲤、鲫、䱗和黄尾鲴;生态浮岛和人工鱼巢的建设对鱼类均有较好的聚集效果;底栖动物增殖放流显著增加了放流物种的丰度、生物量及保护区底栖动物群落生物量,增殖放流效果评价为中等。该自然保护区水域生态修复效果明显,为工程施工影响下水生生物保护区生态修复提供科学依据。     

Substrate composition determines emergence success and development of European nase larvae (Chondrostoma nasus L.)

European nase (Chondrostoma nasus) is a specialist riverine fish, characterised by a complex life cycle making it vulnerable to habitat degradation. Recent findings indicate that, analogously to salmonids, the interstitial zone quality may pose a serious bottleneck for successful recruitment of this species. In this study, nase eggs were exposed to different substrate qualities. First, standardised substrate mixtures with differing fine sediment additions were used. Second, we tested different homogenous gravel fractions for their influence on egg development and emergence success. In both setups, substrate composition significantly affected emergence success, timing of emergence and larvae size at emergence. In the substrate mixtures, emergence was most successful in substratum with no fine sediment addition (98%) and decreased to 55% in substratum with 20% fine sediment addition. Emergence was most successful in the coarsest fraction (93%) and decreased to 47% in the finest fraction. Over all treatments, the time between hatching and emergence from substrate differed by up to 156 degree days, thereby indicating that free embryos of nase use the shelter of the interstitial zone for early ontogeny. These results suggest that a loose and porous stream bed can positively contribute to the development success of eggs and larvae and thereby potentially improve the recruitment of nase populations. It is thus important to consider the substrate and interstitial conditions in the conservation and restoration management of this rheophilic cyprinid.     

Dissolved oxygen controls summer habitat of Clear Lake Hitch (Lavinia exilicauda chi), an imperilled potamodromous cyprinid

Clear Lake Hitch is an imperilled minnow endemic to Clear Lake, Lake County, California, United States listed as threatened under the California Endangered Species Act (ESA) and a candidate for listing under the United States ESA. It exhibits a potamodromous life cycle whereby adults, which reach up to 6 + years in age and over 350 mm in length, migrate into Clear Lake's ephemeral tributaries briefly during spring to spawn. Conservation and management of Clear Lake Hitch is inhibited, in part, by a lack of information on the lacustrine habitat of nonbreeding individuals within Clear Lake. To address this problem, we sampled Clear Lake Hitch with gill nets in a stratified random sampling design to determine the distribution and habitat associations in early summer 2017 and 2018. We identified abundance-habitat relationships for juveniles and adults using Bayesian zero-inflated negative binomial generalised linear mixed modelling. Results indicated that dissolved oxygen concentration was the most important habitat feature measured; juveniles and adults were substantially more abundant in normoxic (≥2 mg/l) than in hypoxic (<2 mg/l) habitat. Both also exhibited weak positive relationships with chlorophyll fluorescence, suggesting relatively productive habitats may support higher numbers of Clear Lake Hitch. Spatially, juveniles were most abundant in nearshore habitats while adults were ubiquitous, indicating an ontogenetic habitat expansion that may be associated with a resource availability-predation risk trade-off. Management actions undertaken to improve hypoxia problems in Clear Lake would also improve Clear Lake Hitch habitat.     

Variation in juvenile steelhead (Oncorhynchus mykiss) dispersal in relation to age and growth performance

Volitional dispersal is a ubiquitous strategy characteristic of species across major faunal groups. Dispersal during the juvenile life stage is of interest because early performance can be critical for determining future success (survival/reproduction). For salmonids, dispersal can influence local density, competition, individual growth and survival, though drivers of dispersal at meso-scales are rarely quantified. Here, we evaluate dispersal of tagged juvenile steelhead (Oncorhynchus mykiss) through habitat units in extended stream reaches (500 m) at sites across a watershed from July to October 2017. Our aim was to quantify the frequency and spatial extent of dispersal, identify links to biotic and abiotic factors, evaluate the implications for individual growth and test for associations between dispersal and migration initiation. Dispersal rates varied between sites, but were consistently higher for age 1+ than for age 0 steelhead (avg. 21% vs. 6% respectively). Age 1+ dispersal probability was positively correlated with time between recapture events and body mass, and negatively correlated with growth rate, maximum temperature experienced and age 1+ density. At sites where there appeared to be growth benefits to remaining sedentary compared to moving, proportionally fewer fish performed dispersal. We found no links between dispersal and timing or probability of migration initiation the following spring. Our results support the hypothesis that although dispersal over intermediate scales (10–1,000 m) might be rare, it could be an important strategy that permits fish to seek out better opportunities (foraging, shelter or otherwise) in underutilised areas.     

复垦年限及植被模式对煤矿复垦土壤微生物多样性的影响

了解露天煤矿区复垦状况及其对土壤微生物的影响机制,对于估算受损生态系统的恢复程度至关重要。该文以采用多种模式复垦的安太堡露天煤矿为研究区域,通过野外调查与采样分析,借助于Biolog EcoPlatesTM方法对复垦区和原地貌(对照)表层土壤中的微生物功能多样性状况进行了探索,评价了复垦年限和复垦植被模式对土壤微生物特征的恢复效应;并从土壤物理化学性质(土壤容重、pH值、土壤有机碳、总氮、速效氮、速效磷和速效钾)和生物性质(土壤微生物量碳和微生物量氮)中筛选可反映土壤微生物功能多样性变化的代表性指示物质。结果表明:1)露天煤矿复垦年限和复垦植被模式均对土壤微生物的功能多样性有明显影响。复垦年限越长的样地中土壤微生物有较高的活性和均匀度,但丰富度较低;若样地的复垦年限较长,复垦植物种植模式对土壤微生物多样性的作用强于复垦时长对其的影响。2)从土壤微生物多样性恢复层面分析,单一植物复垦配置的优化次序为杏树、榆树和柠条,混交林配置较优的选择为柠条×刺槐。3)土壤微生物生物量碳的含量与土壤微生物功能多样性指标Shannon-Wiener指数(ρ=–0.69,P0.01)和McIntosh指数(ρ=–0.69,P0.05)显著负相关,在一定程度上可作为复垦区生物多样性指示物质。研究成果将为露天煤矿及其所在区域的生态恢复、治理和监测提供参考。     

半干旱黄土丘陵区不同土地利用类型植物物种多样性研究

【目的】为了更好地利用半干旱黄土丘陵区的土地资源,促进该区域植被恢复,提高生物多样性,使区域生态环境有所改善。【方法】以半干旱黄土丘陵区龙滩流域的植被为研究对象,对该流域11种典型的土地利用类型(2种农地、自然荒草地、人工牧草地、撂荒草地、灌木林地、5种乔木林地)的植被物种组成和多样性进行了调查研究。【结果】流域内共调查到种子植物56科166属254种,其中裸子植物门3科7属13种,占流域总科、总属、总种的5.36%、4.22%、5.12%;被子植物门53科159属241种,占流域总科、总属、总种的94.64%、98.78%、94.88%。在被子植物门中,双子叶植物纲有50科134属205种,单子叶植物纲有3科25属36种,两纲物种分别占流域总种数的80.71%和14.17%,占该门物种总种数的85.06%和14.94%。不同土地利用类型植被多样性分析结果表明,物种丰富度表现为农地物种丰富度低,人工牧草地、撂荒草地和灌木柠条林地居中,乔木林地(山杏、山毛桃、油松、侧柏、青杨)和天然荒草地高;物种多样性表现为马铃薯农地的物种多样性低,覆膜农地、人工牧草地、撂荒草地及灌木柠条林地居中,自然荒草地和乔木林地比较高;物种均匀度表现为农地、撂荒草地、人工牧草地及灌木柠条林地的均匀度高,自然荒草地居中,乔木林地低。【结论】不同土地利用方式和植被演替恢复时间差异是产生植被多样性差异的基础,也是该区域植被恢复和物种多样性保护需要考虑的重要要素。     

Habitat analysis of the commercial tuna of the Eastern Tropical Pacific Ocean

We have extracted information on the habitats of bigeye (Thunnus obesus), skipjack (Katsuwonus pelamis) and yellowfin (Thunnus albacares) in the Eastern Tropical Pacific Ocean by matching the spatial‐temporal distribution of catch and effort of purse seine and longline fleets collected by the Inter‐American Tropical Tuna Commission with oceanographic conditions and subjecting the matched data to Quotient Analysis and General Additive Models (GAMs). These analyses yielded the following results. The habitats defined by the GAM analysis of young fish differ significantly between two periods, one before and one after the introduction of fish aggregation devices (FADs). This was not true for the older fish caught by longline. We speculate that these changes were caused by the extensive use of FADs. Younger bigeye and yellowfin caught by the purse seine fleet have a different preference of environmental variables compared to older fish caught by longline. This is to be expected since tuna of different age groups have different sizes, metabolic capabilities and swimming skills. Moreover, as revealed by GAMs, the habitats of young fish differ between species to a much larger degree than those of older fish. Our results indicate the fundamental differences between fishing methods, targeted species, and operating region of the two fisheries. Specifically, young bigeye occupy equatorial waters farther from the coast and where the hypoxic layer is deeper, young skipjack occupy more productive waters associated with equatorial and coastal upwelling, and young yellowfin occupy broad areas where waters are underlain by a shallow hypoxic layer.     

Population decline in the endemic Atlantic salmon (Salmo salar) in Kapisillit River,Greenland

Atlantic salmon, Salmo salar L., is found throughout the North Atlantic, with thousands of rivers having spawning populations. In Greenland, spawning is limited to one river in West Greenland, the Kapisillit River (64?N), and the salmon are limited to the lower few kilometres of the system. Using mark–recapture, it was estimated the parr population was 5,953 individuals, and that the population size has declined by 52% since 1959. In spite of this decline, parr density remains high, being between 0.26 and 0.62 parr/m². Using a historical age‐length key, an estimated minimum of 635 smolt will have descended to the sea in 2017. These will be caught in a fishery currently subject to no regulatory measures and fishing remains the most likely driver of the population decline. The genetically distinct population is endemic to Greenland, and managers should implement measures to conserve this genetic integrity and local biodiversity.     

Riparian restoration offsets predicted population consequences of climate warming in a threatened headwater fish

1. Freshwater ecosystems and their associated biota are under increasing threats from multiple stressors including climate and land‐use change. The conservation of these ecosystems must be based on an integration of data including species physiological tolerances, the biotic and abiotic drivers of the distribution of populations, and demographic processes, to provide the comprehensive ecological information necessary for management.
2. This study used a Bayesian belief network (BBN) to synthesize research on northern river blackfish, a threatened species in the upper Condamine River, Australia, into a probabilistic framework capable of predicting the complex relationships that exist between environmental conditions and population success. This study tested how predicted air temperature scenarios for the years 2050 and 2080, and catchment restoration scenarios, would be expected to affect three indices of population success: adult abundance, juvenile abundance, and juvenile recruitment.
3. Compared with current climatic conditions, climate warming scenarios reduced the probability of future population success by between 0.4% and 1.6%. These shifts were almost completely offset, and even improved, when riparian zones were restored at the catchment scale, where changes ranged from an overall decrease of 0.2% to an increase of 1%. To achieve the highest probability of population success, the impacts of warming stream temperatures and the degradation of riparian zones must be mitigated. However, the model showed that there is still a possibility of complete population failure under a wide range of conditions, even when conditions appear to be suitable.
4. To maximize the future population success of river blackfish we recommend targeting the restoration of hydrologically active catchment areas where grazing strongly influences stream biota. The use of a BBN allowed the combination of multiple sources of information to solve complex ecological problems, including how multiple stressors may affect threatened freshwater species.

     

东北平原典型玉米种植区农业景观植物多样性研究——以昌图县为例

非耕作生境是农业景观中的重要组成部分,为生物提供食物和栖息地,对生物多样性保护具有重要意义。本文以辽宁省昌图县为例,选取了20个非耕作生境比例为0~50%的网格(1 km?1 km)为样区,采用典型样地法对调查区域内农业景观中的林地、田间路、草地、沟渠、果园5类主要非耕作生境中的植物群落进行调查,探讨不同非耕作生境类型和比例中植物多样性及其与景观异质性之间的关系。研究结果表明,随着非耕作生境比例增加,植物物种多样性和均匀度先增加后减小,在20%~30%时达到峰值;非耕作生境比例在0~40%范围内时,植物物种丰富度同样呈现先增加后减小,且在20%~30%时达到峰值;非耕作生境比例高于40%时,植物物种丰富度再次出现峰值且高于20%~30%。随着非耕作生境比例的增加,农业景观香浓多样性、香浓均匀度指数和景观斑块形状复杂程度逐渐增加,蔓延度恰好相反。不同生境中重要值最高的均为禾本科植物,但植物种不同;优势种优势度为果园沟渠草地田间路林地。果园、草地和沟渠的物种多样性和均匀度指数显著高于林地和田间路,丰富度指数为草地林地沟渠果园田间路,且草地、果园和田间路的不同调查区域间植物群落指数存在较大的变异性。草地、果园、沟渠、田间路和林地中景观异质性与物种多样性相关性顺次降低。研究结论表明,东北平原典型玉米种植区农业景观中,最适宜非耕作生境比例为20%~30%;非耕作生境中林地、沟渠对物种多样性维持、湿生植物多样性保护具有积极作用;不同生境干扰类型和方式不同,景观异质性与植物物种多样性相关性程度也不同。在今后农业景观生物多样性保护中应综合考虑非耕作生境的类型和比例,干扰的类型和方式等多种因素对生物多样性、生态服务及农业产量的影响。