Feeding ecology and growth of O-group flatfish (sole, dab and plaice) on a nursery ground (Southern Bight of the North Sea)

The food composition of O-group sole Solea solea , dab Limanda limanda and plaice Pleuronectes platessa on a nursery ground at Gravelines, France, included 17–25 taxa. Sole (new settlers) fed mainly on harpacticoid copepods and when 50 mm in size, on polychaetes (Terebellidae). Dab (<40 mm) consumed mainly polychaetes (Magelonidae and Spionidae), and later amphipods, polychaetes (Spionidae) and Hydrozoa. O-group plaice diet was dominated by polychaetes (Terebellidae), crustaceans and molluscs at all sizes. O-group sole, dab and plaice did not compete for food resources, each species being specialized in different prey items. Growth rates during May-July 1998 varied between 0·5 and 0·67 mm day⁻¹ for sole, 0·12 and 0·24 mm day⁻¹ for dab and 0·55 and 0·81 mm day⁻¹ for plaice. For sole and plaice, these estimates were similar to those recorded in other nurseries and also close to the maximal growth predicted by experimental models. This suggests that their growth was not limited by food during the first summer of life.     

Ecological Strategy of Bacteria: Specific Nature of the Problem

An attempt is made to sum up the results of the many years of using the conception of ecological strategy in bacterial ecology. Taking into account the specificities of microorganisms and their natural selection and the coevolution of microorganisms within evolving microbial communities, an inference is derived that the ecological strategy of most bacteria is the sum of a number of particular canonical strategies, some of which are common to higher organisms. It is proposed to call these particular strategies ecological tactics. The author considers this review to be a basis for a discussion.     

Drugs Versus Diets: Disillusions with Dutch Health Care

Biology incorporated into other disciplines is often distorted, alarmingly so in some areas of medicine. Together with other forms of bias, this may have detrimental effects for patients depending on medical research for their health. A case study concerning omeprazole (Losec), one of the acid-suppressive drugs against gastric ulcers, and NSAIDs, non-steroid anti-inflammatory drugs, confirms that distorted biology together with biased health care policies foster disasters in current biomedicine and medical practice. In our country, The Netherlands, omeprazole is presumably the most commonly used medication. NSAIDs are also used in large quantities, increasingly since they have become available as analgesic over-the-counter drugs. Unofficial and official sources tend to inform the general public that the drugs promote human health. We argue that their being used on a massive scale is actually a medical disaster. The health of many patients would be served better if the drugs they take were replaced by proper forms of diet, but the pharmaceutical industry, the most potent force affecting medication policies, appears to prevent a shift in the balance from over-medicalization towards healthy life styles. The shift should come from government agencies responsible for regulation in the medication market. Policies of these agencies are now a dismal failure.     

运用生色基因标记黄瓜根围促生菌(PGPR)筛选菌株

采用三亲交配方法 ,通过Tn7转座系统将lacZY标记基因导入黄瓜根围促生菌 (PG PR)筛选菌株PseudomonasfluorescensCN1 1 6和PseudomonascorrugataCN31的利福平抗性突变株中 ;标记假单胞菌菌株则被赋予了利用乳糖作为唯一碳源的能力 ,在只有乳糖的M9培养基上生长能分解X Gal,菌落显出特有的蓝色 ;经Southern杂交分析 ,证明标记基因lacZY存在于转化菌株的染色体上 ;经验证标记菌株标记性状稳定 ,与对应的野生菌株比较其它性状如培养性状、形态特征、生防效果等基本不变 ;PGPR菌株利福平抗性和生色基因标记的结合 (双标记 )能最大限度地将土壤中引入的PGPR菌株与土著细菌分开 ,检测下限可达 1 0CFU mL ,为PGPR在根围的分子生态学研究提供了一个较好的工具。     

A Gradualist Theory of Discovery in Ecology

The distinction between the context ofdiscovery and the context of justificationrestricts philosophy of science to the rationalreconstruction of theories, and characterizesscientific discovery as rare, theoreticalupheavals that defy rational reconstruction. Kuhnian challenges to the two contextsdistinction show that non-rational elementspersist in the justification of theories, butgo no further to provide a positive account ofdiscovery. A gradualist theory of discoverydeveloped in this paper shows, with supportfrom ecological cases, that discoveries areroutinely made in ecology by extending modelsto new domains, or by making additions toearlier models. The logic of discovery isphilosophically accessible once it isappreciated that model truth is presumed, evenif counterfactually, in ecologists' applicationof models. A gradualist view shows thatmodels' heuristic power routinely leads todiscoveries.     

Measuring and controlling data quality in biological assemblage surveys with special reference to stream benthic macroinvertebrates

1. Biological assemblage surveys primarily aim to characterise species composition and relative abundance at one or more spatial or temporal scales. Data interpretation and conclusions are dependent on how well samples characterise the assemblage of interest. 2. Conventional measures of data quality, e.g. standard deviations or coefficients of variation, were designed for single variable estimation, and they are either insufficient or invalid for assessing the quality of data describing entire assemblages. Similarity indices take species composition and relative abundance into account and may be used to effectively measure and control the quality of data used to characterise assemblage structure. 3. The average Jaccard coefficient (JC) calculated across multiple pairs of replicate samples, i.e. autosimilarity JC (AJC), is conceptually and numerically related to the average coefficient of variation in the densities of all species recorded, a measure of sampling precision, and to the proportion of total species richness sampled, a measure of sampling accuracy. 4. We explored how AJC can be used to assess the effect of different potential sources of error on the quality of assemblage survey data, including the sampling effort used both within regions and at individual sites, the individuals collecting samples, sub‐sampling procedures, and consistency of taxon identification. 5. We found that the autosimilarity‐based approach overcomes most weaknesses associated with conventional measures of data quality and can be used to effectively measure and control the quality of assemblage survey data.     

Fishing Behavior and Decision-Making in an Ecuadorian Community: A Scaled Approach

Debate over how people behave in an open access environment is ongoing in both the social sciences and natural resource management circles. Central to this debate is the question of driving forces behind decisions and behavior toward natural resources within a given area. Using data from an artisanal shrimping community in Ecuador, I demonstrate that behavior in an open access environment, measured in terms of fishing effort, is responsive to both economic and noneconomic factors, the nature of which depends on the temporal scale at which behavior is being measured—hourly, daily, or amount of gear over time. These findings suggest that much of the observed variation between previous studies and corresponding data sets may be a methodological artifact, and the ensuing debates ultimately a result of different methodologies and scales of analyses.     

Did Native Americans influence the northward migration of plants during the Holocene?

Abstract Long‐distance plant dispersal explains the rapid northward migration of plant species during the Holocene but the mechanisms by which it occurred are poorly understood. Given that Native Americans spread numerous cultigens over thousands of kilometres during the late Holocene, I examined historical literature for evidence of non‐cultigen dispersal or cultivation in North America's eastern woodlands. Cultivation references are included because a strong relationship between dispersal and indigenous flora husbandry is assumed. Sixty‐seven texts describing Native American lifestyle, cultural activities, and land management reported some form of plant use. Most accounts, however, focus on cultigen production or the use of indigenous flora for medicine or food without mention of dispersal. Twenty‐four of the texts described the trade, transport, or cultivation of plants indigenous to eastern North American woodlands. Most accounts focus on the informal production of food plants, especially trees and shrubs. Confounding these reports was clear evidence of observer bias, limited botanical knowledge, acculturation, and secrecy by Native American informants. Because of these shortcomings, the likelihood of widespread long‐distance plant dispersal by Native Americans could not be determined using historical literature. This activity was either not widespread or was not observed by, or revealed to, Europeans. To adequately test the Native American plant dispersal hypothesis, direct evidence from other sources (e.g. archaeobotancial data) will be required.