Microhabitat preferences and depth distribution of combtooth blennies (Blenniidae) in the Gulf of Trieste (North Adriatic Sea)     

Martina Orlando-Bonaca  & Lovrenc Lipej 《Marine Ecology》2007,28(3):418-428

The microhabitat preferences and depth distribution of blenniid species (Blenniidae) in the Gulf of Trieste (North Adriatic Sea) were surveyed using the all‐occurrence sampling method, a non‐destructive visual census method, aided by SCUBA diving. Fourteen species were identified during the entire survey. Four species showed to be indiscriminate in their microhabitat choice while 10 species were classified as infrequent in the surveyed coastal area. A statistically significant correlation was found between the blenniid assemblage and nine microhabitat variables. The blenniid assemblage was divided in two main groups, by the use of canonical correspondence analysis, electivity index, and the depth distribution analysis. The first group comprises species that dwell in surface waters and show a high positive correlation with boulders, the presence of Mytilus galloprovincialis, cirripeds and empty holes bored by Lithophaga lithophaga. The second group includes species that mostly inhabit deeper waters and show a high positive correlation with rocks covered by precoralligenous bioformations.  相似文献   

冲绳海槽至马里亚纳海沟重力异常和地壳结构的初步研究     

王述功  高仰 《海洋科学》1989,13(2):24-27

根据我们实测的水深、重力连续剖面资料,计算了自东海至北斐济盆地的地壳厚度。本文旨在对冲绳海槽至马里亚纳海沟的重力异常和地壳结构进行初步的研究。该地段位于太平洋板块俯冲带以西,构造活动十分复杂、剧烈,并含有多种类型的地壳结构。  相似文献   

秦皇岛昌黎黄金海岸的沙丘沉积和发育机理   总被引：7，自引：0，他引：7  

曾照爽  庄振业  祁兴芬  刘志杰 《海洋地质前沿》2003,19(7):23-27

昌黎黄金海岸长40km，分布1～1．5km宽的风成沙丘。主沙丘链高30～40m，顺岸线分布，与其斜交数列新月形横向沙丘链。沙丘以中细砂组成，分选极好，层理构造十分丰富。距今3～4ka以前，沙坝形成时就开始形成沙丘；1915年滦河新三角洲发育以来增加了风沙的输沙量，增高沙丘和扩宽了沙丘带。  相似文献   

Response of zooid size in Cupuladria exfragminis (Bryozoa) to simulated upwelling temperatures     

Aaron O'Dea  Felix Rodríguez  & Tania Romero 《Marine Ecology》2007,28(2):315-323

We investigate the effect of the temperature–size rule upon zooids of the tropical American bryozoan Cupuladria exfragminis. Results show that mean zooid length, zooid width and zooid area vary significantly between clonal replicates of C. exfragminis kept under different controlled temperature conditions. Significantly larger zooids are produced during times of lowered water temperature that are comparable with the temperatures that occur during seasonal upwelling along the Pacific coast of Panama where the animal lives in abundance. Interpolation of data suggests that a drop of 1 °C causes a 5% increase in zooid size, and that almost all variation in zooid size in natural populations can be explained by temperature. Results are discussed in context of the potential use of zooid size variation in cupuladriid bryozoans to measure the strength of seasonal upwelling in ancient seas by analysing zooid size changes in fossil colonies. The technique of cloning cupuladriid colonies by fragmentation is also discussed with reference to its benefits in experimental studies where genotypes need to be controlled or replicated.  相似文献   

In Situ Measurement of Pinna nobilis Shells for Age and Growth Studies:
A New Device     

Jos Rafael García‐March  Antonio Manuel García‐Carrascosa  lvaro Luís Pea 《Marine Ecology》2002,23(3):207-217

Abstract. Pinna nobilis Linnaeus 1758 is an endemic bivalve mollusc in the Mediterranean Sea, where it inhabits seagrass meadows, especially Posidonia oceanica (L.) Delile. It is the largest bivalve in the Mediterranean, reaching lengths up to 120 cm. In its natural habitat, P. nobilis lives with the anterior part of the valve buried in the seabed, attached to Posidonia rhizomes by byssus threads.
This habit makes it impossible to measure its total length directly in situ. As the only way to determine the individual age is the relationship between age and total length, several equations have been proposed to estimate total length by relating it to the unburied parts of the shell. Such measurements are essential to ecological studies that consider age, growth, and population dynamics, and that evaluate the environmental factors that affect this species.
Accurately estimating total length depends on the accuracy and precision of the method employed to measure the unburied shell parts. In this paper, we point out the lack of precision of the instruments and methods used until now; we also demonstrate the reason for this imprecision. A new device to measure unburied parts of Pinna nobilis with a precision comparable to that obtained when measuring extracted valves is described. This device is unaffected by substratum type and reduces measurement time. The latter is a very important feature, because these procedures are usually performed whilst SCUBA diving. Finally, a growth equation has been fitted to the measurements obtained with the new device from a population located in Moraira (Alicante, western Mediterranean).  相似文献   

Size-Fractionated Primary Production Estimated by a Two-Phytoplankton Community Model Applicable to Ocean Color Remote Sensing   总被引：3，自引：0，他引：3  

Takahiko?KamedaEmail author  Joji?Ishizaka 《Journal of Oceanography》2005,61(4):663-672

In order to estimate primary production from ocean color satellite data using the Vertical Generalized Production Model (VGPM; Behrenfeld and Falkowski, 1997), we propose a two-phytoplankton community model. This model is based on the two assumptions that changes in chlorophyll concentration result from changes of large-sized phytoplankton abundance, and chlorophyll specific productivity of phytoplankton tends to be inversely proportional to phytoplankton size. Based on the analysis of primary production data, P _opt ^B , which was one parameter in the VGPM, was modeled as a function of sea surface temperature and sea surface chlorophyll concentration. The two-phytoplankton community model incorporated into the VGPM gave good estimates in a relatively high productive area. Size-fractionated primary production was estimated by the two-phytoplankton community model, and P _opt ^B of small-sized phytoplankton was 4.5 times that of large-sized phytoplankton. This result fell into the ranges observed during field studies.  相似文献   

Using size-based indicators to evaluate the ecosystem effects of fishing   总被引：12，自引：9，他引：12  

Shin  Yunne-Jai; Rochet  Marie-Joelle; Jennings  Simon; Field  John G.; Gislason  Henrik 《ICES Journal of Marine Science》2005,62(3):384-396

  相似文献   

Composition and distribution of phytoplankton with size fraction results at southwestern east/japan sea     

Mi Ok Park 《Ocean Science Journal》2006,41(4):301-313

Abundance and distribution of phytoplankton in seawater at southwestern East/Japan Sea near Gampo were investigated by HPLC analysis of photosynthetic pigments during summer of 1999. Detected photosynthetic pigments were chlorophyll a, b, c₁₊₂ (Chl a, Chl b, Chl c₁₊₂), fucoxanthin (Fuco), prasinoxanthin (Pras), zeaxanthin (Zea), 19’-butanoyloxyfucoxanthin (But-fuco) and beta-carotene (β-Car). Major carotenoid was fucoxanthin (bacillariophyte) and minor carotenoids were Pras (prasinophyte), Zea (cyanophyte) and But-fuco (chrysophyte). Chl a concentrations were in the range of 0.16-8.3/land subsurface chlorophyll maxima were observed at 0-10m at inshore and 30–50 m at offshore. Thermocline and nutricline tilted to the offshore direction showed a mild upwelling condition. Results from size-fraction showed that contribution from nano+picoplankton at Chl a maximum layer was increased from 18% at inshore to 69% at offshore on average. The maximum contribution from nano+picoplankton was found as 87% at St. E4. It was noteworthy that contribution from nano+picoplanktonic crysophytes and green algae to total biomass of phytoplankton was significant at offshore. Satellite images of sea surface temperature indicated that an extensive area of the East/Japan Sea showed lower temperature (<18 °C) but the enhanced Chl a patch was confined to a narrow coastal region in summer, 1999. Exceptionally high flux of low saline water from the Korea/Tsushima Strait seemed to make upwelling weak in summer of 1999 in the study area. Results of comparisons among Chl a from SeaWIFs, HPLC and fluorometric analysis showed that presence of Chl b cause underestimation of Chl a about 30% by fluorometric analysis but overestimation by satellite data about 30-75% compared to HPLC data.  相似文献   

Spatial variation of the intertidal sediments and macrozoo-benthic assemblages along Eighty-mile Beach, North-western Australia   总被引：3，自引：0，他引：3  

Pieter J.C. Honkoop  Grant B. Pearson  Marc S.S. Lavaleye  Theunis Piersma   《Journal of Sea Research》2006,55(4):278-291

The extensive intertidal flats along Eighty-mile Beach in North-western Australia appear to be monotonous and homogeneous and seem ideally suited to study tidal zonation in macrozoo-benthic communities and their possible correlates with characteristics of the sediment. In October 1999, we sampled benthic invertebrates and sediments at a total of 895 sampling stations distributed over six different locations, each location separated by 15 km of unsampled foreshore along Eighty-mile Beach. To test for the presence or absence of patterns of tidal zonation (distinct height-related zones of specific sediment grain sizes or zoobenthic taxonomic groups) or patchiness (distinct patches of specific sediment grain sizes or zoobenthic taxonomic groups not related to tidal height) each location was divided into three along-shore sections and each section (transect) was examined at two or three tidal heights. Zonation was observed for sediment grain sizes. Sediments were coarser at the highest intertidal level and finer towards the low water line. Benthic assemblages also differed among tidal heights, but in terms of species-composition the differences were not consistent among the locations. Each location supported a unique collection of benthic invertebrates. Therefore the hypothesis of the presence of distinct zones of specific species or zoobenthic taxonomic groups was rejected; the presence of benthic patches was confirmed. The distribution of sediments and the composition of benthic assemblages were surprisingly poorly correlated compared to those reported in 12 previous quantitative studies around the world. One possible explanation might be that super-cyclone Vance, which hit the study-area only six months before this study, contributed to this poor correlation. Alternatively, the poor correlation may indicate that biotic interactions are more important than the assumed abiotic structuring.  相似文献   

黄河三角洲河道沉积规律研究Ⅱ. 建林边滩沉积作用机理     

范德江  陈彰榕  栾光忠 《中国海洋大学学报(自然科学版)》2001,31(2):237-242

通过对建林边滩沉积物粒度分布、粒度参数及水体流变性质的分析，阐述了黄河三角洲上河道水流属于牵引流范畴，与低含沙水流无本质上的差别，并探讨沉积物搬运和沉积的基本特征。  相似文献