Settlement,abundance, growth and mortality of juvenile flatfish in a subtropical tidal estuary (Georgia,U.S.A.)

The population dynamics of juveniles of some flatfish species were studied in the Duplin River, a tidal creek in a subtropical salt-marsh area in Georgia, U.S.A. from April until September 1990. Seven species were found. Paralichthys dentatus, Paralichthys lethostigma, Paralichthys oblongus and Trinectus maculatus were relatively rare. Etropus crossotus, Citharichthys spilopterus and Symphurus plagiusa were abundant and settled during the period studied. E. crossotus was the most abundant species with a mean abundance of 18 ind·10⁻² m⁻² (max. 287). Demersal settlement of E. crossotus took place in shallow areas and over sandy bottoms from mid-May to August. Prolonged settlement hampered the calculation of growth rate and instantaneous mortality rate. However, laboratory growth experiments indicated a mean growth of about 0.50 mm·d⁻¹ at 24–28°C. Juveniles of C. spilopterus were already present in the Duplin River in March. Settling continued until the end of April with a mean abundance of 3.5 ind·10⁻² m⁻² (max. 183). With increasing size the juveniles of this species tended to migrate to deeper waters and to the mouth of the river, possibly as a reaction to increasing water temperatures. Maximum growth rate was 1.4 mm·d⁻¹ at about 26°C. The mean instantaneous mortality rate (z) was estimated at 0.03·d⁻¹. Settling of S. plagiusa occurred from mid-May onwards. The mean abundance was 10.3 ind·10⁻² m⁻² (max. 98.3). Newly settled juveniles were most abundant on muddy sediments in the shallow river areas. The maximum growth rate was 1.3 mm·d⁻¹ at about 28°C. The mean instantaneous mortality rate (Z) decreased from 0.04·d⁻¹ in April to 0.01·d⁻¹ in August. At all sites the abundance of juveniles of this species decreased with increasing water depth. Predation experiments indicated that blue crabs (Callinectes similis and C. sapidus) and sea robins (Prionotus sp.) are potential predators on juvenile flatfish. The high abundances of juvenile flatfish indicate that the tidal creeks are an important nursery area. The correspondence between growth rates estimated from field data and those observed in the laboratory suggests that growth in the nursery is mainly related to water temperature and not food limited.     

郑州市动物园草食动物和灵长类动物寄生虫感染情况及驱虫试验

为了解郑州市动物园草食动物和灵长类动物的寄生虫感染情况和采取有效的寄生虫防治措施,采用饱和糖水或饱和盐水漂浮法,分别于2003年、2006年两次对郑州市动物园草食动物和灵长类动物进行了寄生虫感染情况调查,结果：2003年,郑州市动物园15种草食动物寄生虫阳性率高达52.5%（21/40）,但感染强度较小,主要寄生虫为线虫、球虫;金丝猴鞭虫感染严重。2006年,调查21种草食动物和14种灵长类动物,寄生虫总阳性率为32.58%,其中球虫、毛首线虫、绦虫、蛔虫的感染率分别为15.66%、13.25%、4.82%、1.2%;用甲苯咪唑、害获灭、地克珠利等药物对分别对阳性动物进行驱虫试验。结果表明,除金丝猴毛尾线虫外,其余寄生虫病驱虫效果显著。     

Immigration and settlement pattern of Paralichthys dentatus and P. lethostigma in an estuarine nursery ground,North Carolina,U.S.A.

Immigration and settlement pattern of 0-group summer flounder (Paralichthys dentatus) and southern flounder (P. lethostigma) in an estuarine nursery are described. Flounders entering the estuary were transforming larvae. Despite their sympatric occurrence during larval immigration, the two species were found concentrated in different habitats. Sampling along transects within the estuary indicated that newly settled southern flounder were concentrated on tidal flats towards the head of the estuary while greatest numbers of summer flounder were captured on tidal flats in the middle reach of the system. Logistic regression analysis of presence/absence data indicated that salinity affected the distribution of southern flounder while substrate type was an important factor affecting the distribution of summer flounder. Numbers of both species on tidal flats declined in the spring, southern flounder appeared to move upstream to oligohaline riverine habitat and summer flounder appeared to move to high salinity salt marsh habitat. The segregated distribution apparent in juveniles is largely established during the immigration period. Differences in settling behaviour and subsequent movement and/or differential mortality occurring during settlement, appear important in determining the observed distribution of juvenile summer and southern flounder.     

The biology of Solea bleekeri (Teleostei) in Lake St Lucia on the southeast coast of Africa

Several aspects of the biology of Solea bleekeri in Lake St Lucia were investigated, these included occurrence, distribution, reproduction and recruitment, food and feeding, size frequency distribution and the role of estuaries in the species' life cycle. Solea bleekeri was found to occur throughout the system in muddy turbid areas and was largely absent from the eastern shores of the lake where clear water sandy substrata occur. The preferred diet of the species was bivalve siphon tips of the species Solon cylindraceus, when these were in abundant supply. However, when numbers of large (length > 20 mm) specimens were not available then S. bleekeri fed on whatever prey was available in or near the substratum. Analysis of stomach contents under the latter conditions showed that food consumption reflected the composition of the benthos. Large numbers of S. bleekeri spend their entire post-larval and juvenile phases as well as the greater part of their adult life within estuaries. Evidence is presented to support the idea that S. bleekeri breeds in certain areas of the lake and that spawning takes place between September and November. The current data suggest that there may be two populations in St Lucia: one migrates from the system to spawn at sea during winter along with the other marine fish species which utilize estuaries as nursery areas, while the other population breeds within the system. Alternatively there may simply be a single population which normally breeds at sea, but which may breed within the system when conditions are suitable. Recruitment of S. bleekeri into the St Lucia estuarine system takes place from the muddy offshore marine banks and possibly from within the system as well. Solea bleekeri appears not to be totally dependent on estuaries for the completion of its life cycle. The advantages of utilizing these systems for their development relate to the shallow, calm, turbid food-rich areas which estuaries offer. The fact that breeding takes place within St Lucia means that adults and juveniles are present in varying numbers throughout the year.     

The recovery of benthos following the impact of low oxygen content in the German Bight

The oxygen deficiency in the German Bight and in Danish waters 1981–1983 with ensuing benthos mortality was the reason for studying the development and re-establishment of the macrofauna in the following years. These years, from 1984–1987, exhibited more favourable oxygen conditions.The macrofauna of this region with its predominantly sandy substrate belongs to the Tellina fabula community. It is dominated by regular seasonal and ephemeral species such as Spio filicornis, Phoronis spec., Spiophanes bombyx and Lanice conchilega.In 1983, a year with exceptionally low oxygen content in bottom waters (< 1 mg O₂ dm⁻³), the macrofauna showed, in some parts of the investigated area, as reduction of approx. 30–50% in species numbers. Concurrently, the individual numbers of the remaining species were reduced. Beginning in 1984, a rapid recovery of benthic communities was observed. By 1986, biomass as well as species- and individual numbers rose to values similar to those determined by other authors in earlier surveys of the German Bight. In particular, juvenile Echinocardium cordatum and crustaceans have been observed since 1984 in larger numbers.     

龙岩市家养水禽寄生蠕虫的群落生态分析

2008-2010年对闽西山区（龙岩市所辖的七个县市区）进行家养水禽寄生蠕虫的种类分布调查,并以随机抽检的309只水禽体内的所有寄生蠕虫群体作为一个生态群落抽样单位,计算出18种寄生蠕虫种群的生态特征值,然后进行寄生蠕虫的群落生态分析。结果表明：优势种为裂刺四棱线虫和卷棘口吸虫,次优势种为美丽膜壳绦虫、福建单睾绦虫、冠双盔绦虫、鸭对体吸虫、似椎低颈吸虫、分歧单睾绦虫、楔形前殖吸虫、东方次睾吸虫、鸭瓣口线虫、台湾束首线虫。除了细背孔吸虫和大多形棘头虫属于随机分布外,其它16种蠕虫属于聚集分布,聚集度最高的是大膜壳绦虫,其次是矛形剑带绦虫、东方次睾吸虫、宫川棘口吸虫和鸭瓣口线虫。     

Cell abundance and fluorescence of picoplankton in relation to growth irradiance and nitrogen availability in the red sea

The vertical distribution and cellular fluorescence characteristics (chlorophyll and phycoerythrin, PE) of picoplankton (cyanobacteria and prochlorophytes) in the southern Red Sea were investigated in relation to physico-chemical properties of the water column. At all stations two subpopulations of Synechococcus sp. (type A and B) co-occurred, with maximal numbers up to 75 000·cm⁻³. Type B, with dim fluorescence signals, dominated the surface waters whereas type A, with bright fluorescence signals, dominated at greater depth. The divinyl a and b containing Prochlorococcus sp. peaked below the cyanobacteria at the deep chlorophyll maximum (DCM) with maximal cell numbers of 276 000·cm⁻³.Due to thermal stratification the cellular fluorescence (chlorophyll and phycoerythrin) increased with decreasing growth (PAR) irradiance, in an S-shaped manner, but magnitude and slope for the three picoplankters differed. The Synechococcus sp. type B had only a moderate increase in chlorophyll and phycoerythrin fluorescence signals with depth (3.4 and 6.6 fold, respectively), with values saturating at 3% (L_d) of the surface irradiance. The deeper-water type not only possessed much higher values for cellular fluorescence than the B type, but the increase with decreasing light level was also much higer (for chlorophyll by a factor of 11 and PE increased by a factor of 23). In addition, maximal values for these fluorescence signals occurred at an isolume of 1 to 0.5%. These differences in concentrations and responses of the pigment content to the prevailing light climate explain the variation in abundance of both types over the water column.Although the prochlorophytes dominated almost the entire euphotic zone, their adaptation to low light levels was even better than in the two types of cyanobacteria. With depth their increase in chlorophyll fluorescence was similar to that observed in the cyanobacteria (with an increase from surface to bottom of the euphotic zone by a factor of 25). The maximum fluorescence signal was not reached until an I_d of 0.01%. The great ability of the prochlorophytes to adapt their pigmentation to changing light and nitrogen conditions suggests that they can maintain growth under a wide range of environmental conditions.     

山东南四湖省级自然保护区野生鸟类调查及疫源疫病防控初探

旨在通过对山东南四湖自然保护区野生鸟类种类、数量、居留型和群落多样性进行调查,以期为野生鸟类调查及疫源疫病监测奠定数据基础。2018—2021年采用样线法和直接计数法对山东南四湖自然保护区内鸟类进行监测调查,共记录到鸟类15目43科129种,数量34700只。其中国家Ⅰ级重点保护野生动物3种为青头潜鸭(Aythya baeri)、白鹤(Grus leucogeranus)、东方白鹳(Ciconia boyciana),Ⅱ级重点保护野生动物12种。监测种类最多的为雀形目(Passeriformes)共74种,占比57.36%;监测数量上鹤形目最多(47.40%),其次为雀形目(30.02%),雁形目(16.57%);优势种为白骨顶(Fulica atra)、红头潜鸭(Aythya ferina)、白鹭(Egretta garzetta),麻雀(Passer montanus)。鸟类构成以迁徙鸟为主,春、夏季鸟类群落多样性指数最高;鱼塘湿地生境的多样性指数和均匀度指数均最高,自然水域最低。本研究获得了区域内野生鸟类生物多样性基础资料,为未来野生鸟类调查和疫源疫病监测奠定坚实基础。     

Observations on the population dynamics of amphiura filiformis (ophiuroidea: echinodermata) in the southern north sea and its exploitation by the dab,Limanda limanda

Density and growth of an Amphiura filiformis population living at a station in the Oyster Ground (southern North Sea) were monitored during 2 successive years (1982–1984). During this period, the density of adult animals (disk size > 4 mm) was constant and they numerically dominated the 1 mm sieve fraction of the samples. The size distribution of these adults was nearly constant and year classes were not discernable among these larger individuals. Annual recruitment was observed, but growth and survival rates of juveniles were low. During their first year, the disk size of recruits increased from 0.3 to 1.2 mm, and to 2.2 mm in their second year. Approximately 10% of the recruits of the 1982 year class survived the first 8 months. Of the recruits of the 1983 year class only 3% survived after 9 months. Consequently, the contribution by juveniles to the annual production of body tissue was small during the observation period.Adult somatic growth could not be assessed due to the apparent lack of disk growth. Regenerating arms, however, were very common among the larger individuals. Only 4% of the individuals in a sample had intact arms, whereas 55% of the animals (or 20% of all arms) had one or more ‘recent’ distal regenerations distinguishable by their smaller diameter. These regenerations presumably account for a large part of the annual growth and somatic production.Stomach content analysis of demersal fish in this area suggests that Amphiura arms form an important part of the diet of the dab, Limanda limanda. Annual consumption of Amphiura arms by dab was estimated to be 0.84 g wet weight-m⁻², which is equivalent to 420 arms or 6% of the arm population. Considering the large number of adult animals in the population and regeneration capabilities of the species, the grazing by dab will have only little if any effect on the population.     

Macrofauna standing stock of the Dogger Bank. A comparison: II. 1951–1952 versus 1985–1987 are changes in the community of the northeastern part of the Dogger Bank due to environmental changes?

During April/May 1985–1987 some of Ursin's (Ursin, 1960) stations on the Dogger Bank from April/May 1951–1952 were revisited. This paper concentrates on results from the ‘Tail End’, the northeastern part of the Dogger Bank. The polychaete species Ophelia borealis and Goniada maculata, which were dominant species in 1951–1952, showed similar distributions in 1985–1987 on the whole of the Dogger Bank. Changes in the macrofauna distribution are obvious in the increase of opportunistic small polychaete species like Spiophanes bombyx, Scoloplos armiger and Magelona spp. In 1985–1987 these species occurred in high individual numbers per m² all over the Dogger Bank in contrast to 1951–1952, when they were found only in few individuals. Extensive patches of the bivalve species Spisula subtruncata discovered at the northeastern border of the Dogger Bank in the fifties were not found. Only small, fast-growing species like Abra prismatica, Tellina fabula and Montacuta bidentata occurred in high individual numbers per m². In 1987 the total biomass shows a reduction of about 30% in the area compared with 1950–1954Some hypotheses are given to explain the changes in macrofauna distribution on the Dogger Bank between 1950–1954 and 1985–1987, taking into account the increasing eutrophication and pollution.     

Experiments on selection of feeding site and food size in oystercatchers,Haematopus ostralegus,of different social status

Oystercatchers, Haematopus ostralegus, were tested for size selection in two prey species, cockles (Cerastoderma edule) and mussels (Mytilus edulis), under semi-natural, but strictly experimental, conditions that allowed recovery of all shells of prey items eaten.Within any patch of cockles offered, size was not an important selection criterion for the birds. The mean length of cockles consumed always differed less than 1 mm (the measuring accuracy) from the mean length of the cockles presented.When given a choice between patches of different prey quality, the birds tended to select patches according to their relative dominance status, with the most dominant bird feeding mainly in the patch where the prey items had the largest flesh contents. Less dominant birds were forced out of the preferred patch and obtained most of theif food from a patch of presumedly lower quality. One of these birds adapted its prey-handling method and its bill shape for efficient feeding in such a low quality pathc, and it continued feeding in that patch, even after the dominant conspecifics had been removed.In experiments with mussels as prey, the test bird did not select primarily on the basis of size but tended to eat those mussels that were easiest to open.It is concluded that size selection in oystercatchers that eat either cockles or mussels ends with the choice of a certain foraging patch. Within a patch of cockles of one year-class, which is the field condition for the majority of oystercatchers in the Wadden Sea, no selection for size occurs, because this would take too much extra searching time to be profitable.     

Chattonella and Fibrocapsa (Raphidophyceae): First observation of,potentially harmful,red tide organisms in Dutch coastal waters

Species of the potentially toxic and red-tide-forming marine-phytoplankton genera Chattonella and Fibrocapsa (Raphidophyceae) were observed for the first time in 1991 in samples taken in Dutch coastal waters; they were again recorded and enumerated in the following years. Chattonella spp. cell numbers varied with the season, with a maximum in May or June in the Dutch Wadden Sea. Cell numbers of Chattonella and F. japonica Toriumi et Takano were up to 6.0·10³ cells·dm⁻³ in the Dutch Wadden Sea, except at one station in June 1993 when over 10⁴ cells·dm⁻³ Chattonella were counted. In May 1993, a minor bloom (over 2.0·10⁵ cells·dm⁻³) was observed at a station in the southern central North Sea, 100 km northwest of the island of Terschelling. The potentially neurotoxic species Chattonella marina (Subrahmanyan) Hara et Chihara was identified and discriminated from morphologically related species within the class of Raphidophyceae by immunofluorescence. F. japonica could only be clearly identified in live samples; in fixed samples cell morphology was severely affected. The identification of this species was supported by the presence of mucocysts, structures that can be observed readily by optical and electron microscopy.     

野生花生脂肪酸组成的遗传变异及远缘杂交创造高油酸低棕榈酸花生新种质

以花生属19个近缘野生物种87份种质和113份栽野远缘杂交后代为材料, 系统分析野生花生脂肪酸组成的遗传变异及其在栽培种花生脂肪酸改良中的潜力。结果表明, 野生花生的棕榈酸含量与栽培种花生相似, 硬脂酸和油酸含量略低于栽培种花生, 亚油酸含量略高于栽培种。不同物种间以及同一物种内不同资源间的脂肪酸组成存在较大差异。A. rigonii棕榈酸含量较低, A. pusilla和A. duranensis油酸含量较高, A. batizocoi亚油酸含量较高, A. rigonii和A. duranensis油酸和亚油酸含量变幅较大。发掘出油酸含量达60%以上的野生资源2份(19-6, A. duranensis和23-1, A. sp.), 亚油酸含量达40%以上的资源7份, 其中A. rigonii(编号为11-4)亚油酸含量高达48%, 是目前所发现的花生资源中亚油酸含量最高的种质。远缘杂交后代脂肪酸的变异远远超过亲本间的差异, 而且不同组合间的棕榈酸、硬脂酸、油酸和亚油酸含量差异达显著或极显著水平。通过远缘杂交获得了6份油酸含量达64.0%以上且棕榈酸含量在8.5%以下的新种质, 其中yz8913-8油酸含量达67.85%, 比其栽培种亲本提高近30个百分点, 且棕榈酸含量仅7.60%。SRAP检测表明, 这6份远缘杂交后代除整合了亲本的DNA片段外, 还产生了新的DNA片段, 有的还丢掉了亲本的某些片段。农艺性状分析表明, 其中4份种质的综合农艺性状较好, 具有重要育种利用价值。     

Scale and intensity of intertidal habitat use by knots Calidris canutus in the Western Wadden Sea in relation to food,friends and foes

In August–October 1988–1992 we studied the distribution and abundance of knots Calidris canutus around Griend in the western Wadden Sea, and the extent to which these can be explained by benthic prey availability and presence of avian predators. Numbers in the nonbreeding season showed monthly averages of 10 000 to 25 000 birds. Over 100 000 knots were recorded on three occassions. Knots feed in large flocks, individual birds usually experiencing 4 000 to 15 000 flock-mates. The Siberian-breeding/west-African wintering canutus subspecies passed through in late July and early August. Otherwise the Greenlandic/Canadian breeding islandica subspecies was present. Over the period 1964–1992 there were no clear trends in the number of knots, but canutus-knots were particularly abundant in July–August 1991, whereas in 1992 both subspecies were absent.Macoma balthica was the preferred prey of both subspecies. Hydrobia ulvae, Mytilus edulis and Cerastoderma edule were eaten when Macoma was absent close to the surface of the sediment. As Macoma buried deeper from July onwards, canutus faced better average feeding conditions than islandica later in the year. The spatial distributon of knots feeding on the intertidal flats around Griend was best explained by the harvestable biomass of the prevalent prey species in a particular year and season, i.e. Macoma (main prey when their harvestable biomass densities were greater than ca 0.8 g AFDM per m²) and Cerastoderma, and by the avoidance of situations where they run the risk of attack by bird-eating birds. Flocks of knots covered most of the intertidal flats in the Western Dutch Wadden Sea in a couple of tidal cycles. This is about 800 km², much larger than the equivalent area used by knots on their wintering grounds in Mauritania (10–15 km²), a difference that is correlated with prey spectrum, prey availability and predictability.     

条锈菌诱导的小麦MBF1转录辅激活因子基因的克隆及其特征分析

应用电子克隆和RT-PCR方法,从小麦叶片中分离出一个条锈菌诱导的编码MBF1基因的cDNA序列,暂被命名为TaMBF1a。TaMBF1a包含一个完整的429 bp的开放阅读框,编码142个氨基酸,具有MBF1保守结构域;小麦TaMBF1a氨基酸序列与水稻OsMBF1相似性达92%,与拟南芥AtMBF1a相似性达80%。TaMBF1a编码的蛋白可能是核蛋白,且该基因在小麦根、茎、叶组织中表达量基本一致。在小麦与条锈菌的亲和、非亲和互作中,TaMBF1a基因均受条锈菌诱导高水平表达,且非亲和组合表达量高于亲和组合。外源植物激素水杨酸、乙烯、脱落酸也可诱导该基因快速上调表达,表明TaMBF1a可能通过水杨酸、乙烯等信号途径参与小麦对条锈菌的防御反应。     

Cytological data on some wild tropical Vigna species and cultivars from cowpea and asparagus bean

A number of wild species of the genus Vigna were examined as to their chromosome numbers and mitotic metaphase plate configurations. Both the reported diploid numbers 20 and 22, were found or confirmed in a number of wild African species and one originating from East Asia. In species with the chromosome number 20 no deviations from this chromosome number were found. The identification of individual chromosomes is generally limited by their extremely small size. Moreover, the results did not tally with those of other authors. Therefore we abandoned the subject. Thirty-six cultivars of V. unguiculata and V. sesquipedalis of various tropical and subtropical sources were investigated, together with wild or subspontaneous types of V. unguiculata and some closely allied forms. The diploid chromosome numbers 22 and 24 have been mentioned in literature. The following results have been obtained:

1. 1
   A deviation of the chromosome number 22 ranging from 20 to 24 is noted in almost 10% of the cases analysed. Twenty-four chromosomes were found in the majority of these cascs.     
   
   

Assessment of genetic diversity in clover species from Sardinia, Italy, using AFLP analysis

Two species, Trifolium glomeratum and T. nigrescens, from Sardinia, Italy, were analysed for genetic diversity using amplified fragment length polymorphism (AFLP). Variation between and within populations was compared between the inbreeder, T. glomeratum, and the outbreeder, T. nigrescens. Four AFLP primer combinations resulted in a total of 292 loci, of which 75% were polymorphic in T. glomeratum and 85% in Trifolium nigrescens. Variation was highest between populations in both species, but the difference between populations was greater in T. glomeratum (Fst = 0.17), compared with T. nigrescens (Fst = 0.02). Cluster analysis and principal coordinates analysis were used to verify the relationships found. The high level of genetic variation within populations in both species is attributed to the movement of sheep between paddocks, the existence of both species in Sardinia for thousands of years and the persistence of a long‐lived seedbank due to the production of large numbers of small seeds with high levels of hard seededness.     

Stripe rust resistance and genes in Chinese wheat cultivars and breeding lines

Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most important diseases on wheat in China. To assess resistance in wheat cultivars and breeding lines in China, 330 leading cultivars and 164 advanced breeding lines were evaluated with stripe rust. In the greenhouse tests, seedlings of the entries were inoculated separately with several Pst pathotypes. In the field tests, the entries were evaluated for stripe rust resistance in Yangling, Shaanxi Province artificially inoculated and in Tianshui, Gansu Province under natural infection of Pst. The oversummering/wintering and spring epidemic zones of resistance genes were postulated using molecular markers for Yr5, Yr9, Yr10, Yr15, Yr17, Yr18, and Yr26, in combination with resistance spectra. Out of the 494 wheat entries, 16 (3.24 %) entries had all-stage resistance (ASR) in all race tests, 99 (20.04 %) had adult-plant resistance (APR), 28 (5.67 %) were considered to have slow-rusting (SR), and 351 (71.05 %) were susceptible to one or more races in both seedling and adult-plant stages. Advanced breeding lines had a higher percentage (37.2 %) of resistant entries (The sum of ASR, APR and SR) than leading cultivars (24.85 %). Among the epidemic regions, southern Gansu had a higher percentage of resistant entries than any other regions. Based on stripe rust reactions and molecular markers, two cultivars were found to possibly have Yr5 while no entries have Yr10 or Yr15. Resistance genes Yr9, Yr17, Yr18, and Yr26 were found in 134 (29.4 %), 45 (9.1 %), 10 (2 %), and 15 (3 %) entries, respectively.     

Gas sensor array for blueberry fruit disease detection and classification

A conducting polymer gas sensor array (electronic nose) was evaluated for detecting and classifying three common postharvest diseases of blueberry fruit: gray mold caused by Botrytis cinerea, anthracnose caused by Colletotrichum gloeosporioides, and Alternaria rot caused by Alternaria sp. Samples of ripe rabbiteye blueberries (Vaccinium virgatum cv. Brightwell) were inoculated individually with one of the three pathogens or left non-inoculated, and volatiles emanating from the fruit were assessed using the gas sensor array 6–10 d after inoculation in two separate experiments. Principal component analysis of volatile profiles revealed four distinct groups corresponding to the four inoculation treatments. MANOVA, conducted on profiles from individual assessment days or from combined data, confirmed that the four treatments were significantly different (P < 0.0001). A hierarchical cluster analysis indicated two super-clusters, i.e., control cluster (non-inoculated fruit) vs. pathogen cluster (inoculated fruit). Within the pathogen cluster, fruit infected by B. cinerea and Alternaria sp. were more similar to each other than to fruit infected by C. gloeosporioides. A linear Bayesian classifier achieved 90% overall correct classification for data from experiment 1. Tenax? trapping of volatiles with short-path thermal desorption and quantification by gas chromatography–mass spectrometry was used to characterize volatile compounds emanated from the four groups of berries. Six compounds [styrene, 1-methyl-2-(1-methylethyl) benzene, eucalyptol, undecane, 5-methyl-2-(1-methylethyl)-2-cyclohexen-1-one, and thujopsene] were identified as contributing most in distinguishing differences in the volatiles emanating from the fruit due to infection. A canonical discriminant analysis model using the relative concentration of each of these compounds was developed and successfully classified the four categories of berries. This study underscores the potential feasibility of using a gas sensor array for blueberry postharvest quality assessment and fungal disease detection.     

Increased mortality in alternative bivalve prey during a period when the tidal flats of the Dutch Wadden Sea were devoid of mussels

In the course of 1990, stocks of mussels (Mytilus edulis) declined to unprecedentedly low levels in the Dutch Wadden Sea. Hardly a wild mussel bed was left on the tidal flats as a consequence of three years (1988, 1989, and 1990) with failing recruitment and intensive fishing for seed mussels. During these three years, recruitment of cockles (Cerastoderma edule) also failed, whereas fishing was continued. Bird species taking these bivalves as staple food, the oystercatcher (Haematopus ostralegus) and the eider (Somateria mollissima), experienced food shortage. Significant numbers of eiders left the Dutch Wadden Sea area or died, whereas oystercatchers remained abundant trhoughout the winter in most of the Dutch Wadden Sea.Alternative prey species of oystercatchers experienced unsually high mortality rates in the appropriate size classes. This was so in all other common species of bivalves, viz. first-year and older cockles, adult Macoma balthica, and juvenile Mya arenaria. This led to minimal stocks of food for oystercatchers in the late winter of 1991. In March 1991, cockles were depleted and the combined stocks Mya and Macoma would soon have run out of food supply to the overwintering oystercatcher population. Apparently, oystercatchers are able to reduce the stocks of their various bivalve prey species to very low levels.