Colony formation in the Cheilostomatous Bryozoan Fenestrulina Malusii var. Thykeophora

The early stages of colony formation of Fenestrulina malusii var. thyreophora are described, and notes on two other species are included for comparison. In Fenestrulina, early budding patterns are very variable, although some patterns are commoner than others. At the 3‐zooid stage of colony formation there is usually temporary suppression of budding on one side, with the result that the three first‐generation zooids produced from the ancestrula arise 1, 2, 4 in the commonest budding sequence rather than 1, 2, 3; budding patterns may be considerably modified when colonies are obstructed. In Fenestrulina and Eurystomella foraminigera the first zooid budded from the ancestrula lies in the distal midline whereas the second zooid occupies this position in Crassimarginatella papulifera. In all three species the proximal periancestrular zooids are not budded directly from the ancestrula but belong to the third zooidal generation.     

Breeding cycle of the red squat lobster Pleuroncodes monodon H. Milne Edwards, 1837 (Decapoda,Muninidae) from deepwater Pacific of Costa Rica

Reproduction and larval development of the red squat lobster Pleuroncodes monodon is strongly linked to temperature changes provoked by upwelling along the Chilean coast. Here, we propose the hypothesis that both the breeding cycle and the spatial distribution of egg‐bearing females of P. monodon in Costa Rica are related to decreasing water temperatures during seasonal coastal upwelling. To describe the breeding cycle, squat lobsters were collected between February 2007 and January 2008 from the Central Pacific coast of Costa Rica. The presence of egg‐bearing females in other areas of the Costa Rican coast was studied from samples collected during two latitudinal research cruises (August 2008: rainy season; May 2009: dry season). Our results revealed that P. monodon has a marked seasonal breeding period (from November to March), which is associated with decreasing water surface temperatures registered during coastal upwelling events. All females with embryos close to hatching were found in areas surrounding the Gulf of Nicoya, when upwelling events have been reported. The near absence of egg‐bearing females in zones where upwelling does not occur suggests the existence of a strong correlation between upwelling events and the breeding cycle of P. monodon. Our information should be considered when developing management measures for the sustainable use of this potential fishery resource in the Pacific coast of Central America.     

Physical forcing of onshore transport of crab megalopae in the northern Portuguese upwelling system

Wind-driven circulation is a mechanism that may be involved in the shoreward transport of invertebrate larvae. This study investigated the temporal variability of the supply of crab megalopae to an estuary located in the northwest coast of Portugal, which is affected by seasonal upwelling, and related variations in supply to several upwelling indices. Megalopae of the European common shore crab Carcinus maenas (L.). were collected daily, using artificial settlement substrates, during a 3-month period, from March 15 to June 15, 2000. Two settlement episodes were detected, which were consistent with the variation in abundance and size of juvenile crabs. Variations in subtidal sea level and sea surface temperature anomaly were correlated with the strength of along-shore wind stress and consistent with upwelling theory. Contingency analyses showed positive significant associations between increasing intensity of southerly winds and megalopal supply, for time lags of 0–6 d, indicating that shoreward transport occurred during relaxation or reversal of upwelling favourable winds. Associations between megalopal supply and tidal range or the duration of nocturnal flood were not detected. Compared to other studies of the supply of crab megalopae to coastal habitats that used a similar methodology, very low numbers of megalopae were collected during this study. The paucity of C. maenas megalopae in the Ria de Aveiro is in agreement with the low densities of this larval stage in the plankton, and indicates that maintenance of the population is achieved despite a low supply of megalopae.     

东海大陆架掌苔虫属一新种

掌苔虫属(Genus Kinetoskias Danielsen,1868)隶于唇口目、无囊亚目、双胞科(Cheilostomata, Anasca, Bicellariellidae),除南极海域、地中海、加勒比海未见报道外,各地都有记录,但多数种类在北极海域分布较广(Kluge,1953)。掌苔虫系深海类型,有的种能栖息在水深4670米的深海海底。掌苔虫的个虫系草苔虫型(Bugula-type),与草苔虫不同处是个虫始端不分叉。掌苔虫和茎苔虫(Caulibugula Verrill,1900)的群体都由一根长柄和分枝部分构成,但掌苔虫的长柄为膜质;无任何钙质沉淀,仅由一空个虫(keno zooid)构成,而茎苔虫的长柄分节,由许多空个虫构成,往往有钙质加厚,因而两属极易区分。掌苔虫群体分枝的分歧方式属于Harmer的模式7(见Harmer，1923:326,pl,16,fig.7)，即双列分枝在分歧时,两个内个虫(inner zooids)F和G分别由轴个虫(axillary zooid)E相连接,轴个虫产个虫F和G,它伸到与个虫A对应一侧分枝的始端,个虫B不参与个虫数目的复分(图2)。 掌苔虫虽系深海类型,但有的种深度分布范围很广,如Kinetoskias arborescens栖息在水深19-1229米,K.smitti分布在水深65-1210米,S. mitsukurii则分布在水深20-3400米(Kuge1953、1962；Menzies1963)。 掌苔虫的群体借助于膜质长柄插入海底淤泥,由长柄始端分出的微细附根附着在砂粒等基质上。个虫由于特殊的个虫牵引肌(flexor: Zooidal muscles)的伸縮彼此间能活动。鸟头体皆侧位,都长在个虫自由缘上,或位于个虫中点(mid-point)。或位于中点以上(cephlad of the mid-point),或位于中点以下(caudad to the mid-point);有的种鸟头体长在特殊阶梯状突起(step-like process)上,但有些种类无此阶梯状突起。     

Study of 19-year Satellite Sea Surface Temperature Variability along the West Coast of India

The seasonal and interannual variation of upwelling along the west coast of India between 8°N and 24°N was studied for the period 1985 through 2003 using NOAA-AVHRR sea surface temperature data. The seasonal migration of pronounced upwelling, which follows the seasonal shift of the winds in southwest monsoon period and northeast monsoon, was confined. The temporal mean sea surface temperature images clearly show the upwelling season, as does the seasonal sea surface temperature anomaly. These dominate features of the upwelling system are also the most variable, with most of the variance being explained by the seasonal cycle. Quasi-cyclic behavior of seas surface temperature on interannual scales has also been observed.     

Observations and mechanisms of upwelling in the northern KwaZulu-Natal Bight,South Africa

New in situ time-series data were acquired by two ADCP moorings placed on the shelf off Richards Bay on the east coast of South Africa at depths of 25 m and 582 m between October 2009 and August 2010. The 11-month inshore bottom-temperature record revealed five substantial upwelling events lasting 5–10 days each where temperatures decreased by about 7 °C to 17–18 °C. Satellite sea surface temperature data showed these events to coincide with cold-water plumes occupying the northern wedge of the KwaZulu-Natal (KZN) Bight. Numerous shorter duration (1–2 days) upwelling events with less vivid surface expressions were also observed throughout the entire record where bottom temperature dropped by 2–3 °C. The last four months of the record were characterised by a protracted cool period lacking a seasonal trend but punctuated with oscillations of warm and cooler bottom water. In contrast to earlier studies that suggested upwelling was topographically and dynamically driven by the juxtaposition of the Cape St Lucia offset and the Agulhas Current (a solitary mechanism), our analysis showed almost all major and minor cold-water intrusions to coincide with upwelling-favourable north-easterly winds that simultaneously force a south-westerly coastal current. Ekman veering in the bottom boundary layer of the Agulhas Current, and the concomitant movement of cold water up the slope, was found to coexist at times with coastal upwelling, but its absence did not impede inshore cold-water intrusions, calling into question its role as a primary driver of upwelling. Both major and minor upwelling events were observed to promote phytoplankton blooms in the northern KZN Bight which commonly extended to the Thukela River. Wind-driven upwelling was also observed in the inner bight between Richards Bay and Port Durnford, explaining the ribbon of coastal chlorophyll continuously observed on ocean colour images between Cape St Lucia and the Thukela River. Similarities in upwelling character and mechanisms are observed between the northern KZN Bight and the Florida Current shelf systems.     

Ecological and Life History Characteristics of Botryllus schlosseri Tunicata Populations Inhabiting Undersurface Shallow-Water Stones

Abstract. Populations of Botryllus schlosseri PALLAS 1772. a cosmopolitan colonial ascidian. were examined on the undersurface of stones for the first time in three adjoining localities along the Israeli Mediterranean coast. A two-year study of 1589 stones which were inhabited by 1345 colonies, revealed that colony coverage was < 1.5 % of the total available substrate area; values were highest in spring, lowest in winter. The two years differed significantly in the number of colonies · m ², and these numbers were correlated with mean seawater temperatures. Most of the stones contained 1–5 Botryllus colonies year-round; no significant correlation was found between number and stone size. The brown morph was dominant 80 % at all three localities. The distribution of other colour morphs differed between localities. Reproductive colonies were either hermaphroditic or contained male gonads only. Peak reproduction was in the spring, but did not correlate with seawater temperatures. While colony size ranged between I and 1I55zooids, sexually mature colonies consisted of 171–273 zooids on the average, compared with 37–90 zooids for sterile colonies. The three populations differed significantly in several ecological and life history characteristics. This further confirmed past studies indicating that Botryllus populations are characteristically divided into local subpopulations exhibiting microgeographic differences in life history patterns. The results are compared with the accumulated data on other world-wide Botryllus populations residing in other habitats.     

Seasonal variations in abundance,growth and mortality of heterotrophic bacteria in Kagoshima Bay

Seasonal changes in abundance, growth and mortality of heterotrophic bacteria were investigated monthly from collections and dilution experiments in Kagoshima Bay, the southernmost of Japan. Bacteria occurred abundantly with considerable variation in the surface layers where chlorophyll a concentrations were high, whereas seasonal variations were obscure below 100 m. Especially, bacteria showed a decline of cell density toward summer when heterotrophic nano-flagellates increased their abundance. Seasonal and vertical variations in bacterial cell number during the study period were positively correlated with those of water temperature and pico-sized chlorophyll a concentration. Maximum growth and mortality rates showed positive correlations with water temperature but no positive relationships to size-fractionated chlorophyll a. Net increase rate (i.e. in situ rate if abundance changes) was negatively correlated with cell density of heterotrophic nano-flagellates. It is concluded that bacterial abundance is controlled by the resultant (i.e. net growth rate) of the balance between maximum growth and predatory mortality by heterotrophic nano-flagelllates which are both dependent on ambient temperature.     

Spatial and seasonal patterns in abundance and age-composition of Calanus finmarchicus in the Gulf of Maine and on Georges Bank: 1977–1987

The mean seasonal cycle and distribution of various life history stages of C. finmarchicus throughout the Georges Bank (GB)-Gulf of Maine (GOM) region were characterized based on 5966 MARMAP zooplankton samples collected during 106 surveys over a 10-year period (autumn 1977–autumn 1987). A high degree of seasonal and spatial variability in C. finmarchicus abundance throughout the region was evident in contoured portrayals of data, grouped into standard stations and 2-month “seasons”.Eight subareas of the Gulf of Maine-Georges Bank region were identified through cluster analysis of standard stations having similar seasonal patterns in mean abundance of C. finmarchicus stages C3, C4, C5 and adults. These were the northern Gulf of Maine (Northern GOM); southern Gulf of Maine (Southern GOM); Scotian Shelf-coastal Gulf of Maine (Scotian-Coastal GOM); Mass Bay; tidally mixed Georges Bank (Mixed GB); tidal front on the Bank separating mixed from seasonally stratified water (Tidal Front GB); seasonally stratified water on the Bank (Stratified GB) and the Continental Slope adjacent to Georges Bank (SLOPE).A distinct seasonal abundance cycle was present in all subareas, but, the magnitude and timing of annual maxima varied greatly among subareas. Peak abundance was reached early (March–April) in Mixed GB, Tidal Front GB and Mass Bay, and late (July–August) in Northern GOM and Scotian-Coastal GOM. Remaining subareas had maxima in May–June. Abundance increased 10-fold from January–February to March–April and decreased sharply from July–August to September–October in all areas except southern GOM and northern GOM. The amplitude of the annual cycle was weakest in northern GOM and southern GOM, where high concentrations of C. finmarchicus persisted year-round, and strongest in the tidally mixed shallow water on GB, where the sparsest densities of C. finmarchicus occurred most of the year. Abundance curves for the various areas converged in March–April, when C. finmarchicus was ubiquitously very abundant (> 10⁴/10 m²), and diverged from September to December.C. finmarchicus stage distribution in the GB-GOM area was highly negatively correlated with mean water column temperature during the stratified season. This seemed more related to the hydrography of the region, which isolates warmer well mixed Georges Bank from the Gulf of Maine and the stratified areas on the Bank, than to temperature, because Calanus abundances decline on the Bank before water temperatures exceed their preferences.A large part of the spatial and seasonal variation in C. finmarchicus abundance and age structure appears to be tightly coupled to major hydrographic regimes and to major circulation patterns in the region. There was a sharp ecotone between well-mixed Georges Bank and the Gulf of Maine as defined by C. finmarchicus abundance patterns and life history distributions. The ecotone is present year-round but is most apparent during the stratified season (May–October), when thermohaline density gradients and the near-surface current jet along the northern flank are generally strongest. The Gulf of Maine had the highest abundances of C. finmarchicus, and lowest spatial and seasonal variation in the region, while tidally mixed Georges Banks displayed the opposite pattern. This indication of stable population centers in the Gulf of Maine would make it a major source of Calanus in the region, particularly during March–April. Distributional patterns also suggest a strong Calanus influence from Scotian Shelf water in northern Gulf of Maine and on the southern flank of Georges Bank.     

Recruitment of Demosponges (Porifera,Demospongiae) in Rocky and Coral Reef Habitats of Santa Marta,Colombian Caribbean*

Abstract. Recruitment of demosponges (Porifera, Demospongiae) was monitored bimonthly for one year (March 1987 – March 1988) on acrylic plates, and compared to cover of adults, in six rocky and coral reef habitats at Santa Marta, Colombian Caribbean, an area subjected to seasonal, upwelling-outwelling regimes. According to suggestive but not significant trends, recruitment rates are more positively influenced by the total sponge cover near groups of plates than by cover at a larger (habitat) scale; recruit mortality is lower where recruitment is higher. These findings are in agreement with a model of higher settlement (probably due to short-distance dispersal) and lower postsettlement mortality within a few meters of adult sponges. Recruitment varied seasonally, being relatively high from May to November-December during the rainy, outwelling season, when seawater temperature was warmer, water turbidity higher, and benthic algal density lower; it was very low from January to April during the dry, upwelling season.     

夏季琼东上升流的高频变化特征研究*

以往对上升流的研究更多的是关注其年际或季节变化, 高时间分辨率遥感产品的出现使得研究上升流的高频特征成为可能。本文基于融合的逐日海表温度数据, 结合多尺度分割方法, 提出了一种探测上升流冷信号异质性的新算法, 通过上升流面积和强度指数展示了一个完整的琼东上升流过程。分析SST(Sea Surface Temperature)图像的结果表明, 夏季琼东涌升到海面的上升流存在间断期, 平均间隔为6d。每年夏季(6—9月)平均有98d在海表面识别到上升流, 其平均面积为7698km², 平均强度为1.0℃, 两者存在较高的相关性。琼东上升流发生频率与离岸距离成反比, 琼东北海域为高发区。不同上升流的影响因子可能不同, 离岸风、风应力旋度、热带气旋均与上升流短期变化密切相关。     

Fitting a predator–prey model to zooplankton time-series data in the Gironde estuary (France): Ecological significance of the parameters

The relationships between the seasonal fluctuations of the copepod Eurytemora affinis and the mysid Neomysis integer were studied from observed data and experimental results, using a predator–prey model in the oligo-mesohaline area of the Gironde estuary. Mean seasonal fluctuations of abundances were derived from long term data series collected from 1978 to 2003 for both species. In situ predator–prey experiments over a seasonal cycle were used to estimate the seasonal variation of the consumption rate of N. integer on E. affinis and to verify the order of magnitude of the biological parameters given by the model.Predator–prey experiments revealed a high seasonal variation in maximum consumption rates with a mean of 56 ± 9 ind. pred⁻¹ d⁻¹. Maximum consumption rates were always higher for adults than for juveniles of Neomysis integer. Recorded selectivities were higher on nauplii than on copepodids + adults of Eurytemora affinis, both for the juveniles and the adults of N. integer. Neomysis integer mainly fed on meroplanktonic larvae, when they were available in higher abundances, than E. affinis in their environment.Spring increases of abundance for Eurytemora affinis copepodids + adults seemed to be mainly controlled by temperature whereas its decreasing abundance in summer was more related to Neomysis integer predation, suggesting that summer fluctuations of E. affinis abundance are probably controlled by mysid predation at summer times. Using a Lotka–Volterra predator–prey model, the seasonal peak of abundance of the mysid N. integer was well reproduced considering a predation on copepodids + adults of E. affinis, and suggested a dependence between mysid and copepod seasonal variations. However, the seasonal peak amplitude could not be explained solely by a predation on copepodids + adults or on nauplii of the copepod. Thus, N. integer is probably dependent on the seasonal fluctuations of the copepod's abundance, complementing its diet with macrophytal detritus during periods of scarce food.     

南海海域浮游植物叶绿素与海表温度季节变化特征分析

利用 SeaWiFS卫星遥感叶绿素质量浓度及TRMM微波遥感海表温度产品,研究了南海海表叶绿素a的季节变化特征及其同海表温度的关系。研究结果表明,南海叶绿素质量浓度具有很强的季节变化:通常低叶绿素质量浓度(<0.12 mg. m^-3)出现在弱风、高海表温度(>28 °C)的春、夏季节;高叶绿素质量浓度(>0.13 mg·m^-3)出现在有较强风速和较低海表温度(<27 °C)的冬季。线性回归分析显示,南海叶绿素质量浓度同海表温度呈显著负相关关系。尽管在南海南部、南海中部、南海西部及吕宋西北部4个代表子区域的显著性有所差异,但都暗示温度变化所反映的垂向层化调控了营养盐质量浓度和浮游植物量变化。可见,温度可能是影响海洋上层稳定程度及垂向交换强度的重要指标,从而可能调控营养盐及浮游植物的变化。     

Coastal oceanic climate change and variability from 1982 to 2009 around South Africa

Changes and fluctuations in sea surface temperature (SST) around the South African coast are analysed at a monthly scale from 1982 to 2009. There is a statistically significant negative trend of up to 0.5 °C per decade in the southern Benguela from January to August, and a cooling trend of lesser magnitude along the South Coast and in the Port Elizabeth/Port Alfred region from May to August. The cooling is due to an increase in upwelling-favourable south-easterly and easterly winds. There is a positive trend in SST of up to 0.55 °C per decade in most parts of the Agulhas Current system during all months of the year, except for KwaZulu-Natal where warming is in summer. The warming was attributed to an intensification of the Agulhas Current in response to a poleward shift of westerly winds and an increase in trade winds in the South Indian Ocean at relevant latitudes. This intensification of the Agulhas Current could also have contributed to the coastal cooling in the Port Alfred dynamic upwelling region. The El Niño Southern Oscillation (ENSO) is significantly positively correlated at a 95% level with the southern Benguela and South Coast from February to May, and negatively correlated with the Agulhas Current system south of 36° S. The correlation with the Antarctic Annular Oscillation is weaker and less coherent. El Niño suppresses upwelling along the coast, whereas La Niña increases it. Although there does not seem to be a linear relationship between the strength of the ENSO and the magnitude of coastal SST perturbation, El Niño and La Niña appear to be linked to major warm and cool events, respectively, at a seasonal scale in summer in the southern Benguela and along the South Coast. However, care must be taken in interpreting low-resolution reanalysed climate data (ERA40 and NCEP) and optimally interpolated Reynolds SST, such as used here.     

The Humboldt-El Niño scenario: coastal benthic resources and anthropogenic influences,with particular reference to the 1982/83 ENSO

The coastal waters of Peru and Chile are among the most productive of the world's oceans. A striking source of interannual variability in this upwelling ecosystem, El Niño, results in large population and community variations. During El Niño the seasonal upwelling ceases and warm, clear oceanic waters occur close inshore, setting a unique oceanographic scenario in which the performance of populations and communities can be studied. While most attention has been focused on the pelagic components of such systems, numerous changes occur in inshore, benthic populations. Likewise, little attention has been paid to the critical role of humans as predators or active users of inshore, benthic resources. Humans as components of the ecosystem can impose significant alterations on population and community structure. In this paper the fishery statistics of three economically important inshore, benthic resources (the gastropod Concholepas concholepas, the cephalopod Octopus vulgaris and the kelp Lessonia nigrescens) are analysed in relation to the strong 1982/83 El Niño event. In particular, trends are described for landings in the far northern regions of Chile, where the marked effect of El Niño was concurrent with high levels of exploitation of C. concholepas and L. nigrescens.     

The Cabo Frio upwelling overrides geographical patterns in the population dynamics of the shrimp Artemesia longinaris Spence Bate, 1888 (Decapoda: Penaeidae)

Upwelling areas are among the most productive ecosystems on the planet, influencing the biology of marine organisms. This study investigated the population dynamics of the shrimp Artemesia longinaris in two regions in southeastern Brazil, one inside (Macaé—Rio de Janeiro State) and one outside (Ubatuba—State of São Paulo) the Cabo Frio upwelling area. The aim was to verify the influence of the upwelling phenomenon on the abundance, growth, longevity, size of sexual maturity, and reproductive period of the species. In total, 188,902 individuals were captured at Macaé and 3,461 at Ubatuba. Individuals captured at Macaé showed larger maximum size, higher longevity, and slower growth rate, besides reaching sexual maturity at larger sizes than at Ubatuba. Continuous reproduction was observed in both regions, with juvenile recruitment peaks in spring and summer. Local conditions observed at Macaé were influenced by the Cabo Frio upwelling zone, characterized by productive and cooler waters that are around 20°C during most of the year. The upwelling phenomenon is probably the main factor influencing the population parameters studied here, changing the geographic patterns previously observed for the variation of these parameters in A. longinaris.     

Oceanographic controls on the carbon isotopic compositions of sinking particles from the Cariaco Basin

This study examined the relationship between carbon isotopic composition of sinking organic matter (OM) and the biological, physical and chemical properties of the surface ocean in the Cariaco Basin. The ¹³C/¹²C ratio of OM (δ¹³C_org) in sinking particles was determined on sediment trap samples from four depths collected from 1996 to 1999 as part of the CArbon Retention In A Colored Ocean time series. Water column properties, including temperature, productivity, chlorophyll and concentration of dissolved CO₂, were concurrently measured on monthly cruises. The δ¹³C_org varied from a high of –17.7‰ to a low of –22.6‰ during the study period. The variation of the δ¹³C_org throughout seasonal cycles was directly proportional to the strength of upwelling and was negatively correlated with temperature (r²=0.64). During the 1996–1997 upwelling event, the strongest during the study period, the δ¹³C_org increased by 4.4‰ whereas during the 1998–1999 upwelling event, the weakest during the study period, the δ¹³C_org only increased by 3.3‰. Contrary to most previous studies, we observed a negative relationship (r²=0.53) between [CO_2 aq] and the estimated isotopic fractionation factor (ε_p). However, there was no correlation between ε_p and the calculated growth rates indicating that there was non-diffusive uptake of carbon into phytoplankton cells. It thus appears that [CO_2 aq] does not control the δ¹³C_org in the water column of the study site. The best explanation for the isotopic enrichment observed is a carbon concentrating mechanism (CCM) in phytoplankton. The existence of a CCM in phytoplankton has major implications for the interpretation of the δ¹³C_org in the Cariaco Basin.     

Structure of potential upwelling areas in the Philippines

The three-dimensional structure of two potential mesoscale upwelling areas that are located in the external waters of the Philippine archipelago (i.e. northwest of Luzon and east of Mindanao) were constructed by analysis of historical data. A unique characteristic of both upwelling sites is that they can be identified by their anomalously cold subsurface temperatures rather than sea surface temperature distributions. As such, they cannot be observed in sea surface temperature fields derived by satellite imagery. The data used in the analysis were obtained from the National Oceanographic Data Center hydrographic database. Objective analysis was performed to produce monthly temperature fields at several standard depths within the upper 500 m of the region 0–30°N and 100–140°E with a horizontal grid resolution of 0.5°. The extent and timing of these upwelling areas are described. A review of existing hypothesis on the mechanisms for their evolution and seasonal modulation are presented. The change in heat content during the upwelling season is greater than 300 W m⁻² in both areas. Based on the excursion of isotherms, vertical velocities of 83 cm day⁻¹ and 26 cm day⁻¹ were obtained for upwelling northwest of Luzon and east of Mindanao, respectively.