Calculation of väisalä‐brunt frequencies and specific volume distributions of sea water     

A. E. Gilmour 《新西兰海洋与淡水研究杂志》2013,47(3):217-222

An expression is derived for the Vaisala‐Brunt frequency in terms of the gradients of potential temperature and salinity. Modifications to facilitate calculations are suggested. A new method for expressing the specific volume distribution in terms of pressure, potential temperature, and salinity is also discussed.  相似文献   

Pleistocene Ross seal (ommatophoca Rossi) from New Zealand (note)     

Judith E. King 《新西兰海洋与淡水研究杂志》2013,47(4):391-397

A fossil seal jaw from the Early Pleistocene (Wanganui Series; Hautawan Stage) of Napier, New Zealand, is identified as that of an Ommatophoca rossi juvenile of less than 1.8 m body length.  相似文献   

Population ecology of the snail Melampus bidentatus in changing salt marsh landscapes          下载免费PDF全文

Roman Zajac  Erin Kelly  Danielle Perry  Ivana Espinosa 《Marine Ecology》2017,38(2)

We studied the population ecology of the snail Melampus bidentatus in relation to patch composition and landscape structure across several salt marsh systems in Connecticut, USA. These marshes have changed significantly over the past 40–50 years including loss of total area, increased areas of short Spartina alterniflora, and decreased areas and fragmentation of Spartina patens. These changes are consistent with tidal inundation patterns that indicate frequent flooding of high marsh areas. Melampus bidentatus densities were highly variable, both among different salt marsh systems and locations within specific marshes, but were generally similar among short Sp. alterniflora and Sp. patens patches within locations. Densities were lowest where the marsh was regularly inundated at high tide and only remnant Sp. patens patches remained. Almost no snails were found in bare patches. Areas that had large Sp. patens patches adjacent to short Sp. alterniflora supported the highest M. bidentatus densities. Population size‐structure varied significantly among patch types, with higher proportions of large individuals in short Sp. alterniflora and hummocked Sp. patens patches than in large and remnant Sp. patens patches. This was likely due to size‐selective predation and/or higher snail growth rates due to better food resource conditions in short Sp. alterniflora patches. Egg mass densities and the number of eggs per egg mass were highest in short Sp. alterniflora. Our results indicate that M. bidentatus is resilient to the level and patterns of salt marsh change evident at our study sites. Indeed, snail densities were significantly higher than reported in other field studies, suggesting that increased patch areas of short Sp. alterniflora and associated environmental conditions at our study sites may provide more favorable habitats than previously when marshes were dominated by extensive Sp. patens meadows. However, there may be threshold conditions that could overwhelm the ability of M. bidentatus to maintain itself within salt marsh systems where changes in hydrology, sedimentation and other factors lead to increased numbers of bare patches and ponds and loss of short Sp. alterniflora and Sp. patens. Studies of the responses of resident and transient fauna to salt marsh change are critically needed in order to better understand the implications for salt marsh ecosystem dynamics and services.  相似文献   

Sexual reproduction and short-term fitness advantage in the rotifer Brachionus calyciflorus: implications for the coexistence of sympatric clones     

孙栋  马蕊  刘玮  牛翠娟 《中国海洋湖沼学报》2013,31(5):987-993

Large numbers of rotifer eggs from sediment resting egg banks may hatch simultaneously under appropriate conditions;therefore,natural populations are likely to be multiclonal in a growing season.A recent field investigation showed that subordinate and ephemeral clones were able to establish populations in an environment with several strongly dominant clone populations.However,it was not clear how the subordinate populations maintained their growth under these conditions where the crowding signal would induce high levels of sexual reproduction in the dominant clone populations.In the present study,we conducted a continuous passage to 60 generations for new populations at three different temperatures(15°C,25°C,and 35°C).These populations emerged from resting eggs produced by a clone population.At the first,30th,and 60th generations,the populations were sampled and fitness was assayed using the life-table method.We found a significant short-term fitness advantage for populations newly emerged from resting eggs produced by a clone population of the rotifer Brachionus calyciflorus,followed by a significant decrease in relative fitness with long-term continuous passage.Our results suggested that the early shortterm fitness advantage was important for later-hatched and subordinate clone populations in an environment with multiple sympatric clones.The early short-term fitness might also promote the coexistence of sympatric clones because it could help to offset the cost of early sexual reproduction.  相似文献   

Age, growth and reproduction of the sand smelt Atherina boyeri Risso, 1810 in the Gomishan wetland – southeast Caspian Sea     

Rahman Patimar  Morteza Yousefi  Seyyed Morteza Hosieni 《Estuarine, Coastal and Shelf Science》2009,81(4):457-462

A total of 2256 specimens of Atherina boyeri caught in Gomishan wetland (a marsh lagoon located at the southeast Caspian Sea) during spawning season from February to August 2007 were examined for life-history attributes. The population has a 4-year life cycle. Length–weight relationship was estimated as W = 0.0053TL^3.0181 for males and W = 0.0050TL^3.063 for females, being allometrically positive for both sexes. The von Bertalanffy growth function fitted to back-calculated size at age data was: Lt = 155.17[1 − exp − 0.28(t + 0.738)] and Lt = 162.77[1 − exp − 0.27(t + 0.727)] for males and females respectively. The sex ratio was 1:1.30 in favor of females. The reproductive season, evaluated from GSI, extended from March to July, with a peak in March. The average absolute and relative fecundities were 2976 eggs and 874 eggs g⁻¹ of body weight respectively. The diameter of oocytes ranged from 0.03 to 0.20 mm with a mean value of 0.68. The life-history patterns of A. boyeri in the population under study imply that the population of this species in the southeast Caspian Sea differs markedly from those of other localities of its range distribution. The differences were thought to be due to differences in geographical locations.  相似文献   

Continuous light delays sexual maturation and increases growth of Atlantic cod (Gadus morhua L.) in sea cages   总被引：1，自引：0，他引：1  

Taranger  G.L.; Aardal  L.; Hansen  T.; Kjesbu  O.S. 《ICES Journal of Marine Science》2006,63(2):365-375

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海湾扇贝南移后繁殖期的变动     

陈敏  何进金 《台湾海峡》1994,(2)

本文根据海湾扇贝的肥满度、肉柱百分数、性腺指数及消化脓指数等指标的周年变化，并结合性腺的组织切片来确定其繁殖期。结果表明，海湾扇贝南移后的繁殖期是从每年的10月下旬开始的，直到翌年5月下旬，其中4月为繁殖盛期。繁殖期间，扇贝的性腺分批成熟，分批排放，并有消退与恢复的现象。同时，海湾扇贝引进中国北方海区并南移福建后，其繁殖规律与原产地（美国大西洋沿岸）的繁殖期有很大的不同。  相似文献   

The dynamics of the summer-spawning population of the loliginid squid Sepioteuthis australis in Tasmania, Australia--a conveyor belt of recruits     

Jackson  George D; Pecl  Gretta 《ICES Journal of Marine Science》2003,60(2):290-296

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Using global genome approaches to address problems in cod mariculture     

Goetz  Frederick W.; McCauley  Linda; Goetz  Giles W.; Norberg  Birgitta 《ICES Journal of Marine Science》2006,63(2):393-399

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Growth, reproductive cycle, and movement of berried European lobsters (Homarus gammarus) in a local stock off southwestern Norway     

Agnalt  Ann-Lisbeth; Kristiansen  Tore S.; Jorstad  Knut E. 《ICES Journal of Marine Science》2007,64(2):288-297

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