Identification of a New Set of Polypeptidic Sex Pheromones from Cuttlefish (Sepia officinalis)

Marine Biotechnology - The common English Channel cuttlefish (Sepia officinalis) reproduces every year on very localized coastal spawning areas after a west–east horizontal migration of...     

Ontogenetic trajectories of septal spacing in modern cuttlefishes are phylogenetically dependent

In this study, the ontogenetic trajectories of septal spacing between succeeding chambers of five modern cuttlefishes, Sepia esculenta, S. lycidas, S. latimanus, S. pharaonic and Sepiella japonica, which were all wild-caught around Japan, were analysed. The ontogenetic trajectories of septal spacing of all examined cuttlefishes demonstrate a decrease in septal spacing followed by an increase during the earliest ontogenetic stage. This trend is assumed to be related to hatching. After the rapid decrease and increase in septal spacing, species-dependent trends occur irrespective of sex and locality. Based on cluster analyses of general trends recognized in each species, the five examined species can be categorized into two groups: (1) a group by S. pharaonis, S. esculenta and Sepiella japonica; and (2) S. latimanus and S. lycidas as more distant branching groups within the five examined species. This classification is concordant with some phylogenetic clades determined from DNA analyses. Therefore, we hypothesized that the ontogenetic trajectories of septal spacing among modern cuttlefishes are phylogenetically dependent. If this hypothesis holds in fossil cuttlefishes, the examination of ontogenetic trajectories of septal spacing would give new insight into the recognition not only of the life history but also of the phylogeny of fossil cuttlefishes.     

温度对拟目乌贼幼体日生长率和存活率的影响

以温度为单因素变量,在人工饲养环境中,分析水温对拟目乌贼幼体日生长率与存活率的影响。实验结果表明,当水温处于28.1～32℃之间时,拟目乌贼幼体的日生长率与水温呈正相关关系;当水温处于32～32.67℃时,拟目乌贼幼体的日生长率与水温呈负相关关系;当水温处于29.5～32.6℃时,拟目乌贼幼体不易出现幼体死亡(死亡率<6.25%),适宜拟目乌贼幼体的存活;而当水温处于32.3～34℃之间时,拟目乌贼幼体出现了13.16%～61.16%的幼体死亡,不适宜拟目乌贼幼体的存活。实验结果表明,当水温处于29.5～32℃之间时,拟目乌贼幼体的存活率高(存活率>93.75%),且日生长率处于0.24%～1.76%,适宜拟目乌贼幼体的存活。     

Pilchard (Sardina pilchardus, Walbaum) egg distribution in the English Channel from plankton surveys in 1978, 1981, 1988 and 1991

The distribution, abundance and production of pilchard (Sardinapilchardus, Walbaum) eggs are described from a series of planktonsurveys in the English Channel. These are discussed in relationto surface temperature and compared with the results from previouslypublished surveys. The surveys confirm that spawning beginsin the western English Channel during the second half of March,progresses eastwards and is 2–3 weeks later in the easternEnglish Channel. Some spawning still occurs in the southernNorth Sea and at a similar level to that found on surveys in1950 and 1967. Pilchard eggs were found developing in surfacetemperatures down to 8.5C. Concentrations as high as 1500 m^–2were found in the Bay of the Seine at 10–10.5C. Thesesurveys suggest that increasing egg production is linked toincreasing sea temperature and that the major production occursin the western English Channel at surface temperatures >14.5C.     

Squid stock fluctuations and water temperature: temporal analysis of English Channel Loliginidae

1. Monthly series of abundance indexes for the English Channel squid stock, based on fishery statistics of the United Kingdom (1980–93) and France (1986–96), were compared with water temperature data. The two objectives of the study were to test empirical predictive models and to analyse the stock–environment relationship at various time scales; both correlation and time-series statistical techniques were applied. Sea surface temperature (SST) showed inter-annual fluctuations and month-to-month auto-correlation in addition to the annual cycle.
2. Trends in squid landings and temperature at the annual scale were found to be related, whatever the statistical method used (moving averages, cumulative functions or regression using averaged data).
3. Variable selection applied in a 'multi-month' model suggested that fishing season indexes could be predicted from temperatures observed in the previous winter. The link between mild winter conditions and cohort success in winter/spring spawning species suggested that early life survival (and/or growth) was involved. This empirical model is a first step in the development of environment-predicted recruitment indexes useful for management advice.
4. Seasonal decomposition was performed on both the squid resource data and SST data in search of short-term relationships. In spite of the flexibility of the loliginid life-cycle, no significant relationship was found between squid seasonally adjusted indexes and temperature anomalies in the previous months. This underlined the conclusion that temperature effect on cohort success was not constant throughout the year.     

Regional climatic warming drives long-term community changes of British marine fish

Climatic change has been implicated as the cause of abundance fluctuations in marine fish populations worldwide, but the effects on whole communities are poorly understood. We examined the effects of regional climatic change on two fish assemblages using independent datasets from inshore marine (English Channel, 1913-2002) and estuarine environments (Bristol Channel, 1981-2001). Our results show that climatic change has had dramatic effects on community composition. Each assemblage contained a subset of dominant species whose abundances were strongly linked to annual mean sea-surface temperature. Species' latitudinal ranges were not good predictors of species-level responses, however, and the same species did not show congruent trends between sites. This suggests that within a region, populations of the same species may respond differently to climatic change, possibly owing to additional local environmental determinants, interspecific ecological interactions and dispersal capacity. This will make species-level responses difficult to predict within geographically differentiated communities.     

DEVELOPMENTAL INTEGRATION RELATED TO BUOYANCY CONTROL IN NAUTILOIDS: EVIDENCE FROM UNUSUAL SEPTAL APPROXIMATION AND ONTOGENETIC ALLOMETRIES IN A JURASSIC SPECIES

Abstract:  The meaning of modifications in septal spacing that often coincide with maturity in extant Nautilus and fossil nautiloids, and also in ammonoids, remains controversial. In the Callovian nautilid species Paracenoceras marocense Miller and Collinson, 1952 , the extent of decrease in septal spacing and the exceptional number of approximated septa are correlated with an unusual positive ontogenetic allometry in whorl-width expansion. This allometric growth implies that the threshold weight of the animal, requiring the formation of a new chamber to maintain near-neutral buoyancy, was reached for an increasingly shorter angular length of shell added to the aperture. Thus, the available space for the newly forming chamber behind the advancing body was reduced accordingly. Ontogenetic modifications in septal spacing are linked to relative growth of the animal. The flexibility in the mechanisms of buoyancy regulation would be expected to have been a critical factor affecting the possible set of ontogenetic trajectories in chambered cephalopods and thus the realm of variation upon which selection could act.     

Some aspects of the biology of the horse mackerel [Trachurus trachurus (L.)] in waters around Britain

Evidence is presented which supports the hypothesis of a seasonal migration between the North Sea and the western English Channel. Fish caught west of Britain have a different length composition and there is some evidence of a North–South migration. Analysis of stomach contents shows that the species is a plankton feeder. Data on seasonal growth in young fish show the growth-rate is most rapid between August and December; length-frequency distributions of two year-classes were bimodal. The use of the otolith burning technique revealed up to 35 check rings, as compared with the reported maximum age of 10 years. With the exception of ring numbers 1 to 3, it could not be established the rings were annual.     

Spatial variability in digenean metacercariae infection of 0-group common sole Solea solea among nurseries along the French Atlantic coast

We sampled 0-group sole juveniles (N = 174) in September and October 2003 in 9 major nurseries located along the French Atlantic coast (English Channel and Bay of Biscay). 0-group sole were infected with 3 genera of digenean metacercariae, Timoniella spp. (Acanthostomidae), Prosorhynchus crucibulum and Prosorhynchus sp. A (Bucephalidae), Podocotyle sp. (Opecoelidae), and an unidentified species of Digenea. Parasite infection levels in the English Channel nurseries were lower, and the community composition was different from Bay of Biscay nurseries. We hypothesize that the difference between geographic areas was due to differences in first intermediate host communities and, to a lesser extent, because of lower temperatures in the English Channel compared to the Bay of Biscay. For the Bay of Biscay nurseries, mean total parasite abundance was strongly negatively correlated with mean annual river flow. This relationship may be the result of the more upstream location of 0-group sole nurseries in estuaries so that fish were further from local points of parasite transmission than those in embayed nurseries. Digenean metacercariae load may be influenced by 3 major local factors, i.e. abundance and proximity of the first intermediate hosts and cercariae dispersal capacities.     

Potential of Schinopsis lorentzii for dendrochronological studies in subtropical dry Chaco forests of South America

The lack of knowledge about species with well-delimited annual rings has hampered the development of dendrochronological records in the subtropical Chaco region of South America. In this contribution, we present the first tree-ring chronology of Schinopsis lorentzii (Anacardiaceae), a dominant species in the semi-arid Chaco. Cross sections were collected near Las Lajitas, Salta, Argentina, and processed following the methods commonly used in dendrochronology. Annual growth variations between radii from a single individual and between radii from different trees were highly correlated. To determine the climatic parameters that control radial growth, we compared annual tree-ring variations against regional temperature and precipitation records. Correlation functions indicate that tree growth is highly influenced by spring–summer rainfall variations, which represent more than 80% of the total annual precipitation. The chronology, which covers the interval from 1829 to 2004, provides a context for the unprecedented increase in precipitation since the mid-1970s in the region. The climatic-sensitivity of S. lorentzii provides a unique opportunity to reconstruct precipitation variations during past centuries in the extensive semiarid regions of subtropical South America.     

哀牢山亚热带常绿阔叶林内外地温分布特征

地温是森林气候重要的环境因素之一,与植物生长密切相关,对地温的深入研究有助于揭示森林生态系统功能和评估森林环境效益。本文利用哀牢山亚热带常绿阔叶林林内和林外旷地(气象站)地温数据,分析发现:哀牢山亚热带常绿阔叶林林内外的地温均呈单峰型日变化,与林外相比,林内地温具有明显日变化的深度较浅(仅在20cm深度以上);林内平均地温具有显著日变化的深度在春季和秋季(20cm)要大于夏季和冬季(15cm);与林外相比,林内各层地温均小于同层的林外地温,并且林内地温的日变幅和年变幅也小于同深度的林外地温。总体来看,林外地温的年变幅和日变幅大于林内。     

Overfishing and the Replacement of Demersal Finfish by Shellfish: An Example from the English Channel

The worldwide depletion of major fish stocks through intensive industrial fishing is thought to have profoundly altered the trophic structure of marine ecosystems. Here we assess changes in the trophic structure of the English Channel marine ecosystem using a 90-year time-series (1920–2010) of commercial fishery landings. Our analysis was based on estimates of the mean trophic level (mTL) of annual landings and the Fishing-in-Balance index (FiB). Food webs of the Channel ecosystem have been altered, as shown by a significant decline in the mTL of fishery landings whilst increases in the FiB index suggest increased fishing effort and fishery expansion. Large, high trophic level species (e.g. spurdog, cod, ling) have been increasingly replaced by smaller, low trophic level fish (e.g. small spotted catsharks) and invertebrates (e.g. scallops, crabs and lobster). Declining trophic levels in fisheries catches have occurred worldwide, with fish catches progressively being replaced by invertebrates. We argue that a network of fisheries closures would help rebalance the trophic status of the Channel and allow regeneration of marine ecosystems.     

Variation in size and growth of the great scallop Pecten maximus along a latitudinal gradient

Understanding the relationship between growth and temperature will aid in the evaluation of thermal stress and threats to ectotherms in the context of anticipated climate changes. Most Pecten maximus scallops living at high latitudes in the northern hemisphere have a larger maximum body size than individuals further south, a common pattern among many ectotherms. We investigated differences in daily shell growth among scallop populations along the Northeast Atlantic coast from Spain to Norway. This study design allowed us to address precisely whether the asymptotic size observed along a latitudinal gradient, mainly defined by a temperature gradient, results from differences in annual or daily growth rates, or a difference in the length of the growing season. We found that low annual growth rates in northern populations are not due to low daily growth values, but to the smaller number of days available each year to achieve growth compared to the south. We documented a decrease in the annual number of growth days with age regardless of latitude. However, despite initially lower annual growth performances in terms of growing season length and growth rate, differences in asymptotic size as a function of latitude resulted from persistent annual growth performances in the north and sharp declines in the south. Our measurements of daily growth rates throughout life in a long-lived ectothermic species provide new insight into spatio-temporal variations in growth dynamics and growing season length that cannot be accounted for by classical growth models that only address asymptotic size and annual growth rate.     

4种生态因子对虎斑乌贼幼体生长与存活的影响

旨在研究温度、盐度、饵料种类、投饵量对虎斑乌贼（Sepia pharaonis）幼体生长与存活率的影响,以确定其生长发育的最佳生态条件,为人工育苗提供理论依据。在室内控制条件下,采用单因子试验研究了不同温度（18、21、24、27、30和33℃）、不同盐度（18、21、24、27、30和33）、不同饵料种类（虾糜、活糠虾、卤虫无节幼体、桡足类、死糠虾、虾糜＋强化卤虫后无节幼体、强化卤虫后无节幼体）、活糠虾不同投饵量（0、2、4、6、8和10 g/d）对虎斑乌贼幼体生长发育的影响。结果显示：不同温度对虎斑乌贼幼体生长影响显著（P〈0.05）,最适温度为24-27℃,在最适温度下,存活率为84.4%-91.1%,特定生长率为4.82%-6.13%,存活率（y）与温度（x）的函数关系为y=-0.15x3＋30.637x-447.002（r2=0.923）。幼体适宜盐度为24-33,最适盐度为27,在最适盐度条件下,其存活率为（90.0±5.29）%,特定生长率为（3.71±0.34）%。投喂7种开口饵料,以活糠虾效果最佳,存活率为（96.7±2.94）%,特定生长率为（3.77±0.23）%;强化卤虫后无节幼体效果次之,存活率为（95.6±2.31）%,特定生长率为（2.54±0.15）%,其余各组培养效果均不理想。投喂活糠虾,随着投饵量的增加,其存活率随之提高,摄食量（y）与个体重（x）的回归方程为y=0.227x-0.063（r2=0.921）。     

Geographic distribution, seasonal life cycle, biomass and production of a planktonic copepod Calarms sinicus in the Inland Sea of Japan and its neighboring Pacific Ocean

The geographical distribution, seasonal life cycle, biomassand production of a copepod Calanus sinicus were investigatedin and around Kii Channel of the Inland Sea of Japan. The distributioncenter of the population was located in Kii Channel. The patternof the seasonal variation in abundance of copepodites and adultsdiffered geographically within the study area. In Kii Channel,for example, they were most abundant in June-July and leastabundant in October. Over the study area, the reproduction ofC.sinicus took place throughout the year, indicating the absenceof diapause phase. In adults, females usually outnumbered males.The prosome length of late copepodites and adults was inverselycorrelated with water temperature. The annual mean biomass washighest (4.87 mg C m^–3 or 231 mg C m^–2) in Kii Channel.The potential production rate of the population exhibited aseasonal variation more or less similar to that of the biomassand the annual potential production rate was 358 mg C m^–3year^–1 (14.1 g C m^–2 year^–1) in Kii Channel.Daily production and biomass (P/B) ratios in Kii Channel increasedfrom 0.11 at 11.8°C to 0.26 at 20°C.     

拟目乌贼幼体日摄食量及其对体重影响

在人工养殖条件下,对拟目乌贼幼体的日摄食量和日增重率进行了分析。结果显示,在水温、盐度、pH等条件相对稳定的环境下,10～15d的拟目乌贼幼体平均日摄食虾苗(体长0.5mm)的条数分别是8、11、12、13、78、83条,在这种摄食量下,拟目乌贼幼体的日增重率分别为6.8%、5.68%、6.44%、8.81%、12.5%。其胴长、体重的生长符合S型曲线生长规律。     

Fluctuations naturelles et évolution artificielle des biocénoses macrozoobenthiques intertidales de trois estuaires des côtes françaises de la Manche

The study of the intertidal benthic population dynamics in three estuaries of the English Channel (Baie des Veys, Seine estuary, Baie de Somme:France) brings to light two types of species:

u

key-species which directly respond to the local disturbance of the environmental conditions in their densities (Spionidae, Capitellidae) and in their growth rates (Cerastoderma edule);

target-species such as Macoma balthica which can endure brief changes in the environmental factors and shows no sign of long-lasting consequences on its population dynamics; yet, it fully integrates long-term changes through its numbers and productivity.

The parallel between such a regular study of the seasonal variations on selected sites and various base line surveys allows the authors to discuss the COST 647 sampling programm in order to selectrms, range of temperature) from human disturbances (embankments, chemical pollution, eutrophication). Diverse hypothesis are suggested which bring about several research topics to be developed within a european cooperation.     

大兴安岭兴安落叶松径向生长对气候响应的时空变化

根据兴安落叶松在大兴安岭山脉的分布特征,沿纬度设置了9个采样点,分析了兴安落叶松径向生长对气候因子响应的空间差异和时间动态。结果表明:总体上所有采样点的兴安落叶松径向生长与夏季(6—8月)标准化降水蒸散指数(SPEI)及降水量、2月SPEI及降水量呈正相关,与3月温度呈负相关。在空间上,南部年均温较高区域的兴安落叶松径向生长与2月SPEI呈显著正相关,在北部年均温较低的区域与3月温度呈显著负相关。在时间上,兴安落叶松生长-气候关系不稳定。随着温度升高,在年均温较高区域,夏季SPEI和降水量对树木生长的正效应以及夏季温度的负响应显著增强;在年均温较低区域,树木生长与3月温度负响应增强更明显。这表明气候变化改变了树木生长-气候关系,而且存在明显空间差异。在未来气候暖干化的背景下,大兴安岭兴安落叶松径向生长会受到抑制,在年均温较高且降水量较少的南部地区会因夏季水分亏缺和冬季干旱而衰退,温度较低的北部地区则可能因冬季干旱和冬季变暖而使生长受到抑制。     

Fitness and physiology in a variable environment

The relationship between physiological traits and fitness often depends on environmental conditions. In variable environments, different species may be favored through time, which can influence both the nature of trait evolution and the ecological dynamics underlying community composition. To determine how fluctuating environmental conditions favor species with different physiological traits over time, we combined long-term data on survival and fecundity of species in a desert annual plant community with data on weather and physiological traits. For each year, we regressed the standardized annual fitness of each species on its position along a tradeoff between relative growth rate and water-use efficiency. Next, we determined how variations in the slopes and intercepts of these fitness-physiology functions related to year-to-year variations in temperature and precipitation. Years with a relatively high percentage of small rain events and a greater number of days between precipitation pulse events tended to be worse, on average, for all desert annual species. Species with high relative growth rates and low water-use efficiency had greater standardized annual fitness than other species in years with greater numbers of large rain events. Conversely, species with high water-use efficiency had greater standardized annual fitness in years with small rain events and warm temperatures late in the growing season. These results reveal how weather variables interact with physiological traits of co-occurring species to determine interannual variations in survival and fecundity, which has important implications for understanding population and community dynamics.