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1.
Role of environment and hydrography in determining the picoplankton community structure of Sagami Bay,Japan 总被引:1,自引:0,他引:1
Smita Mitbavkar Toshiro Saino Naho Horimoto Jota Kanda Takashi Ishimaru 《Journal of Oceanography》2009,65(2):195-208
Seasonal variations in the picoplankton community were investigated from June 2002 to March 2004 within the photic zone of
Sagami Bay, Japan. The study area was mostly dominated by coastal waters during the warm period (mixed layer water temperature
≥ 18°C). During the cold period (mixed layer water temperature ≤ 18°C), the water mass was characterized by low temperature
and high saline waters indicative of the North Pacific Subtropical Mode Water (NPSTMW). Occasionally, a third type of water
mass characterized by high temperature and low saline properties was observed, which could be evidence of the intrusion of
warm Kuroshio waters. Synechococcus was the dominant picophytoplankton (5−28 × 1011 cells m−2) followed by Prochlorococcus (1−5 × 1011 cells m−2) and picoeukaryotes during the warm period. Heterotrophic bacteria dominated the picoplankton community throughout the year,
especially in the warm period. During the Kuroshio Current advection, cyanobacterial abundance was high whereas that of picoeukaryotes
and heterotrophic bacteria was low. During the cold period, homogeneously distributed, lower picophytoplankton cell densities
were observed. The dominance of Synechococcus in the warm period reflects the importance of high temperature, low salinity and high Photosynthetically Active Radiation
(PAR) on its distribution. Cyanobacterial and heterotrophic bacterial abundance showed a positive correlation with temperature.
Prochlorococcus and picoeukaryotes showed a positive correlation with nutrients. Picoeukaryotes were the major contributors to the picophytoplankton
carbon biomass. The annual picophytoplankton contribution to the photosynthetic biomass was 32 ± 4%. These observations suggest
that the environmental conditions, combined with the seasonal variability in the source of the water mass, determines the
community structure of picoplankton, which contributes substantially to the phytoplankton biomass and can play a very important
role in the food web dynamics of Sagami Bay. 相似文献
2.
Temporal variation in phytoplankton composition related to water mass properties in the central part of Sagami Bay 总被引:1,自引:0,他引:1
Fuminori Hashihama Naho Horimoto Jota Kanda Ken Furuya Takashi Ishimaru Toshiro Saino 《Journal of Oceanography》2008,64(1):23-37
Temporal variations in water mass properties and the composition of phytoplankton pigments in the central part of Sagami Bay
were investigated by monthly observations from June 2002 to May 2004. Eleven pigments were quantified using high-performance
liquid chromatography (HPLC) from 100%, 20%, and 5% light depths relative to the surface; the class-specific composition of
phytoplankton community was then obtained by CHEMTAX analysis. The study area was influenced by the Kuroshio water for most
of the observation period. The mean contribution of diatoms in all samples was relatively low (29%), while that of flagellates,
mainly chlorophytes or cryptophytes, was quite high (60%). The phytoplankton composition at the three depths was uniform throughout
the observation period, indicating that the vertical structure of the phytoplankton community did not develop significantly
over time. A distinct temporal pattern was observed: flagellates dominated during the summer of 2002 and the winters of 2002–2003
and 2003–2004, while diatoms dominated during the summer of 2003. This pattern was associated with water mass changes. The
community in the summer of 2003 was influenced by coastal water. While no distinct spring bloom of phytoplankton was observed,
a weak increase in chlorophyll a was observed during the spring of 2004. Ocean color satellite data showed that fluctuations in chlorophyll a concentrations at time scales much shorter than a month occurred during the spring of 2003 and that the elevations in chlorophyll
a levels were not continuous. The fluctuations were probably associated with rapid flushing by the Kuroshio water, which has
low chlorophyll a content. 相似文献
3.
本文根据2007年3月至2008年2月期间在泉州地区3个海湾的调查资料,对其浮性鱼卵和仔稚鱼的种类组成与数量分布特点进行初步研究和探讨.结果表明,本调查海域共出现鱼卵和仔稚鱼51种(含未定种),隶属于21科,主要是近岸底层鱼类、近海中上层鱼类和港湾河口型鱼类三个生态类型.各站鱼卵总平均丰度是81.2彬网,仔稚鱼总平均丰度31.0个/网.数量平面分布呈现优势种明显,占总量比例大,不同季节不同海湾差别较大,规律性不强等特点.整体数量上与往年比有下降趋势. 相似文献
4.
Temporal changes in the vertical distribution of metazoan meiofaunal groups were examined at a bathyal site (depth 1450 m) in Sagami Bay from December 1996 to August 1998. Among major meiofaunal groups, the vertical distributions of copepods (adults and copepodites), and kinorhynchs changed seasonally and they concentrated in the shallower part in the sediment profile when CPE concentrations were higher. Seasonal changes in the vertical distributions of ovigerous females and nauplii of copepods were not related to CPE concentrations, but related to that of total copepods. On the other hand, nematodes, ostracods, and polychaetes did not show seasonal migrations. These results suggest that there is a difference in the response to the sedimentation of organic matter between metazoan meiofaunal taxa. 相似文献
5.
Seasonal and interannual variations in physicochemical properties were investigated in the neritic area of Sagami Bay, Kanagawa,
Japan, from December 2000 to December 2005. Physicochemical properties (i.e. temperature, salinity, density, dissolved oxygen
and dissolved inorganic nutrient concentration) revealed clear seasonal variations, which were similar to each other during
all 5 years. Temperature, salinity and dissolved inorganic nutrients showed rapid, drastic variations within a few days and/or
weeks. These variations are related to sea levels, principally due to the shifting effects of the Kuroshio Current axis: they
were strongly affected by the Kuroshio Water and other waters, when sea level difference was greater than ca. 35 cm and lower
than ca. 15 cm, respectively. Temperature difference (DF
T
) increased with sea level difference, and the difference of salinity and dissolved inorganic nutrients (NH4
+-N, NO3
−+NO2
−-N, NH4
++NO3
−+NO2
−-N, PO4
3−-P and SiO2-Si) increased and decreased with DF
T
, respectively. All these correlations are significant. Total dissolved inorganic nitrogen (N), phosphate (P) and silicate
(Si) revealed seasonal variations in the ranges of 0.57–16.08, 0.0070–0.91 and 0.22–46.38 μM, respectively. From the regression equations between these elements allowed the following relation to be obtained; Si:N:P
= 14.8:13.4:1. Dissolved inorganic nutrients were characterized by Si and/or P deficiency, especially in the upper layer (0–20
m depth) during summer. Single and/or combined elements are discussed on the basis of potential and stoichiometric nutrient
limitations, which could restrict phytoplankton (diatom) growth as a limiting factor. 相似文献
6.
7.
Tomoharu Senjyu Noriko Asano Masaji Matsuyama Takashi Ishimaru 《Journal of Oceanography》1998,54(1):29-44
Intermediate intrusion of low salinity water (LSW) into Sagami Bay was investigated on the basis of CTD data taken in Sagami
Bay and off the Boso Peninsula in 1993–1994. In October 1993, water of low temperature (<7.0°C), low salinity (<34.20 psu)
and high dissolved oxygen concentration (>3.5 ml I−1) intruded along the isopycnal surface of {ie29-1} at depths of 320–500 m from the Oshima East Channel to the center of the
bay. On the other hand, the LSW was absent in Sagami Bay in the period of September–November 1994, though it was always found
to the south off the Boso Peninsula. Salinity and dissolved oxygen distributions on relevant isopycnal surfaces and water
characteristics of LSW cores revealed that the LSW intruded from the south off the Boso Peninsula to Sagami Bay through the
Oshima East Channel. The LSW cores were distributed on the continental slope along 500–1000 m isobaths and its onshore-offshore
scales were two to three times the internal deformation radius. Initial phosphate concentrations in the LSW revealed its origin
in the northern seas. These facts suggest that the observed LSW is the submerged Oyashio Water and it flows southwestward
along the continental slope as a density current in the rotating fluid. The variation of the LSW near the center of Sagami
Bay is closely related to the Kuroshio flow path. The duration of LSW in Sagami Bay is 0.5 to 1.5 months. 相似文献
8.
9.
We applied genetic makers to identify Calanus species occurring in Sagami Bay, Japan, in order to investigate their vertical distribution in the upper 1000 m. First, interspecific genetic distances of three gene loci, mitochondrial small ribosomal RNA (srRNA), nuclear internal transcribed spacers 1 (ITS1) and 2 (ITS2), were estimated from morphologically distinguishable adult females of Calanus sinicus, Calanus jashnovi and Calanus pacificus that were collected from Sagami Bay, the Kuroshio Extension and the Oyashio region, respectively. The highest levels of interspecific genetic distance were observed in srRNA, followed by ITS1 and ITS2. The intraspecific genetic distances within C. sinicus were much lower than the interspecific genetic distances, indicating that DNA sequences in these loci are consistent with the morphological differences. This information was used as a criterion for species identification based on DNA sequence variation, and allowed us to identify the fifth copepodites (CVs) or younger stages of these species. Next, the vertical distribution of Calanus species was investigated in Sagami Bay in May 2006, on the basis of a stratified sampling in the upper 1000 m. By applying the genetic markers, 23 individuals comprising all copepodite stages were allocated into either C. sinicus or C. jashnovi, and the small- and large-sized CVs were identified as C. sinicus and C. jashnovi, respectively. The total abundance of C. sinicus was highest at 0-50 m and decreased with depth. On the contrary, CV individuals of C. sinicus were abundant not only in 0-50 m but also below 200 m with minimum occurrences in 150-200 m depth. C. jashnovi was much less abundant than C. sinicus and comprised of only CIV and CV which occurred in the upper 100 m and deeper than 50 m depths, respectively. The abundance of C. sinicus in the 1000-m water column of Sagami Bay was at a level comparable to that in shelf waters, suggesting the importance of off-shelf individuals in the biological production and organic transport in the respective areas. 相似文献
10.
根据2007年8月至2009年10月期间在福建省主要海湾的调查资料,对其浮性鱼卵和仔稚鱼的种类组成与数量分布特点进行初步研究和探讨.结果表明,本调查海域共出现鱼卵和仔稚鱼68种,隶属于29科,主要是近海中上层鱼类、浅海底层鱼类和港湾河口型鱼类3个生态类型.各站鱼卵总平均丰度是497.5粒/网,仔稚鱼总平均丰度50.8个/网.优势种明显,占总量比例大;不同季节和不同海湾的种类数相差不大;数量平面分布呈现不同季节不同海湾差别较大,规律性不强,偶然性大等特点. 相似文献
11.
12.
Ichthyoplankton and microzooplankton were collected twice monthly for one year at a single station in Biscayne Bay, Florida. Based on approximate 10-m3, 333-μm mesh bongo net samples, the mean annual densities were 17·7 m?3 and 1·8 m?3 for fish eggs and larvae, respectively. Ichthyoplankton was most abundant in spring-summer. The most common fish larvae were bay anchovy (Anchoa mitchilli), spotted dragonet (Callionymus pauciradiatus), thread herring (Opisthonema oglinum) and gobies (Gobiidae), which comprised 50% of all larvae collected. A comparison of 35-μm and 333-μm mesh, bongo net collections revealed that mean densities of fish larvae were 8·5 times higher in the smaller mesh. The most abundant microzooplankton, based on 35-μm bongo net collections, were copepod nauplii, <100 μm in width, which averaged 90·41?1 and tintinnids which averaged 168·51?1. The mean density of microzooplankton <100 μm wide, potentially suitable food for first-feeding fish larvae, was 104·91?1, exclusive of tintinnids, and 273·41?1 including tintinninds. Excepting tintinnids, seasonal variability in microzooplankton abundance was low relative to that for ichthyoplankton. High microzooplankton densities, combined with low seasonal variability, indicated that feeding conditions for fish larvae were usually good in Biscayne Bay. Copepods, especially nauplii, were the predominant food of fish larvae (71% of all food items). Only mollusc veliger larvae (18% of all food items) were highly preferred prey but they were a small component of most larval fish diets. Average width of prey eaten by first-feeding larvae was 74 μm. Prey size increased in relation to larval length. 相似文献
13.
胶州湾鱼卵、仔鱼和稚鱼的分布 总被引:7,自引:0,他引:7
2003年1月-2004年1月在胶州湾海域逐月进行连续13个航次的调查,对胶州湾鱼卵、仔鱼和稚鱼的种类组成、丰度和主要种类的分布进行了研究。结果表明,采集到的鱼卵均为浮性鱼卵。鱼卵丰度最高值出现在8月(5.02粒/m3),次之为5月(4.97粒/m3)。共采集到仔、稚鱼10种,隶属9科10属,优势种为刺鱼叚虎鱼、斑鱼祭和玉筋鱼。根据出现的季节和出现时间的长短,将仔、稚鱼分为暖季类群、暖季短时类群和冷季类群三种类群。暖季类群较冷季类群占有明显的优势。暖季短时类群的种数、丰度和站位出现率都比较低。仔、稚鱼的丰度、种数的季节变化显著,最大值均出现在6月份,丰度是16.34尾/m3,种数为7种,与海水月平均温度的季节变化节律基本一致。 相似文献
14.
Ellen E. Deason 《Estuarine, Coastal and Shelf Science》1982,15(2):121-134
Surveys of the distribution, abundance and size of the ctenophore Mnemiopsis leidyi were carried out in Narragansett Bay, R.I. over a 5-year period, 1975–1979. Yearly variations were observed in time of initiation of the ctenophore increase and maximum abundance. Biomass maxima ranged from 0·2 to 3 g dry weight m?3 at Station 2 in lower Narragansett Bay while maximum abundance varied from 20 to 100 animals m?3. Ctenophores less than 1 cm in length generally composed up to 50% of the biomass and 95% of the numerical abundance during the peak of the M. leidyi pulse. During the 1978 maxima and the declining stages of the pulse each year, 100% of the population was composed of small animals. M. leidyi populations increased earlier, reached greater maximum abundances, and were more highly dominated by small animals in the upper bay than toward the mouth of the bay. The averageclearance rate of M. leidyi larvae feeding on A. tonsa at 22°C was 0·36 l mg?1 dry weight day?1, with apparent selection for nauplii relative to copepodites. Predation and excretion rates applied to ctenophore biomass estimated for Narragansett Bay indicated that M. leidyi excretion is minor but predation removed a bay-wide mean of 20% of the zooplankton standing stock daily during August of 1975 and 1976. Variation in M. leidyi predation at Station 2 was inversely related to mean zooplankton biomass during August and September, which increased 4-fold during the 5-year period. 相似文献
15.
春季珠江口水域鱼卵和仔稚鱼的分布及其与环境因子的关系 总被引:4,自引:0,他引:4
根据2004~2007年春季珠江口水域10个站位的鱼卵和仔稚鱼调查资料,着重就鱼卵和仔稚鱼的数量分布和年际变化及其与环境因子的相关关系进行研究.结果表明:其鱼卵和仔稚鱼隶属于9目33科58种(类),以鲈形目种类数所占比例最高(为53.4%),其次为鲱形目(为20.7%).鱼卵和仔稚鱼大致分成半咸水性、近岸性和近海性3个生态类群.鱼卵和仔稚鱼优势种类共9种,其中鱼卵优势种为6种,仔稚鱼的也为6种.青洲附近水域是春季鱼卵和仔稚鱼的最主要分布区域之一.鱼卵和仔稚鱼数量的年际变化明显,鱼卵和仔稚鱼个体数量的最大值均出现在2006年.水温、pH值和溶解氧含量是影响鱼卵个体数量的较显著因子,盐度和溶解氧含量为影响仔稚鱼个体数量的较显著因子.盐度、pH值及溶解氧、悬浮物、叶绿素a含量对鱼卵和仔稚鱼种类数均有不同程度的影响. 相似文献
16.
The occurrence of fish larvae and the effect of diel and tidal variation on catches was studied at about biweekly intervals for a year in Whangateau Harbour, a small well mixed northern New Zealand estuary. Larvae from 31 taxa were identified. The annual pattern of larval occurrence was typical for fish in temperate waters, with a major peak of abundance in early summer. For six taxa, larval densities were significantly greater in night-time than in daytime catches, and analysis of length-frequency distributions suggested that for two species this was due to daytime net avoidance.No significant differences were found between the densities of larvae caught on flood and ebb tides, but changes in length-frequency distributions were significant for two species. Recently hatched larvae of an unidentified goby were found leaving the harbour, where they were probably spawned, while older larvae of this species appeared to be recruiting back in. Larvae of the flounder Rhobosolea plebeia were also apparently recruiting into the harbour. In the absence of a two-layered circulation pattern larvae relied upon tidal transport for recruitment, and probaby ensured their retention by rapidly settling to the bottom. 相似文献
17.
台湾南湾区秋末冬初海樽类的种类组成和数量分布 总被引:6,自引:0,他引:6
根据2001年11月2--3日和12月8--10日在台湾南湾12个测站分别用2种圆锥形浮游生物网(长180cm,网口直径45cm,网目333μm或200μm)采集表层和底层的浮游动物样品,分析了南湾浮游海樽类的种类组成和数量分布,其鉴定海樽类16利,其中7种为台湾周围海域新记录。东方双尾纽鳃樽和小齿海樽为优势种。南湾海樽类的种类数及个体数量均以12月多于11月。讨论了水文条件与海樽类时空分布的关系,认为外海高盐水团足南湾冬季海樽类生态特征的主要制约因子。典型的高温高盐种大西洋火体虫、长吻纽鳃樽、安纽鳃樽、多手纽鳃樽、书氏纽鳃樽、羽环纽鳃樽和斑点纽鳃樽等可以作为外海高温高盐水入侵南湾的指标种。与邻近海域比较,秋冬季南湾与台湾岛以东海域海樽类的区系特征比与台湾海峡和南海北部更加相似。 相似文献
18.
19.
2010年胶州湾网采浮游植物种类组成与数量的周年变化 总被引:1,自引:1,他引:1
为了研究胶州湾网采浮游植物的种类组成与数量变化,作者根据2010年的胶州湾调查资料,对调查区浮游植物丰度、优势种类和季节变化进行分析研究。结果表明,胶州湾浮游植物主要由硅藻和甲藻两大类组成,硅藻占据绝对优势地位。除了7月以外,甲藻/硅藻比均0.2。生态类型主要以近岸广布种和暖温带种为主,在不同季节也出现了少数暖水种和外洋种。浮游植物丰度表现为明显的"双周期",冬、春两季较高,夏、秋两季较低。2月为全年最高峰,数量为1108×104个/m3,10月为夏、秋两季的高峰,数量为458.7×104个/m3。浮游植物群落的多样性指数平均为1.9。 相似文献
20.
福建三沙湾浮性鱼卵和仔、稚鱼的分布 总被引:6,自引:1,他引:6
本文根据1990年2~11月在三沙湾海域分别进行4个季节调查的资料,对三沙湾鱼卵和仔、稚鱼的种类组成、丰度和主要种类的分布进行研究和探讨.结果表明,本海区共出现鱼卵和仔、稚鱼26种,分别隶属于17科22属.在数量上,鱼卵最高值出现在春季(5月),其中鱼卵丰度较高的种类是真鲷、带鱼、鲾和康氏小公鱼等种类.仔稚鱼以夏季丰度最高,并以鰕虎鱼丰度(71.8%)最高.在分布上,鱼卵的丰度以三都岛东北部和东吾洋海域最高,仔稚鱼以三都岛东部最为密集.这表明本海区的鱼类的主要产卵季节是春季和夏季.其数量、分布与水温及桡足类的分布关系密切. 相似文献