Albacore off the north‐west coast of New Zealand,February 1972

During two trolling surveys in February 1972, albacore, Thunnus alalunga (Bonnaterre), were located between Cape Reinga and Cape Egmont, but were more abundant between Kaipara Harbour and Albatross Point. Fish catches and associated hydrological data are presented. Albacore were caught only in areas where the sea surface temperatures were between 18.5°c and 21.3°c, and usually in areas where the water was blue and the bottom depth between 45 m and 80 m. The albacore were mainly of the 2‐ and 3‐year age‐groups. Of the 665 fish landed, 449 were tagged and released, but no recoveries have been made.

Commercial vessels located albacore within 20 km of New Plymouth during the summers of 1970 and 1971 when sea surface temperatures were 1.5–2.5°c higher than in February 1972, probably because of a more southward extension of the West Auckland Current in 1970 and 1971.     

Some seasonal water temperature patterns in the Hauraki gulf,New Zealand

The changing pattern of water temperature in the Hauraki Gulf at approximately two‐monthly intervals during one and one‐half seasonal cycles in 1965–66 was determined from sea surface temperatures and bathythermograph profiles.

Surface and bottom temperatures ranged from 22.0°c and 20.5°c respectively in March to 12.5°c and 13.0°c in July‐September. Seasonal temperature ranges and short‐term variations were greatest in the shallow south‐west Gulf.

In winter the Gulf water was coolest close to shore. It was typically isothermal in depth but a temperature inversion of approximately l°c frequently formed, probably because of the combination of strong winds and an increased outflow of cool, low salinity water from harbours and bays. A similar inversion in Colville Channel may have been caused by more complex tidal and/or ocean current conditions.

In spring and summer the Gulf became thermally stratified, with warmest temperatures in the shallow areas. Thermoclines were generally irregular in position and size, and probably represented solar heating and minor current boundaries rather than a distinct separation of major water masses. In late summer and autumn bottom temperatures increased and almost equalled the maximum surface temperature.

During autumn surface water temperatures close to land decreased rapidly to return the Gulf to its winter isothermal condition.

Local factors (wind, rainfall, tides, depth of water, and proximity to land) probably influence sea temperatures in the Gulf. Seawards of a line from Cape Rodney to Cape Colville oceanic conditions prevail; water temperatures are more constant and increase to seaward in both winter and summer.

Oceanic and Gulf waters meet and mix in the Rodney‐Colville area, and Gulf water is transported east through Colville Channel. The extent of oceanic water penetration into the Gulf at depth is unknown.     

North Cape — a ‘nursery area’ for the packhorse rock lobster,Jasus verreauxi (Deeapoda: Palinuridae)

In the North Cape area (34°26'S, 173°07'E) there appears to be a concentration of late juvenile packhorse rock lobsters, Jasus verreauxi (H. Milne Edwards'), which subsequently contributes significantly to the nearby fishery for adult J. verreauxi off Cape Reinga. Evidence for this is based on the overall smaller size and fewer mature rock lobsters at North Cape compared to areas nearby, and on the results of tagging experiments carried out during 1976–77. Rock lobsters tagged at North Cape moved 21–514 km, mainly west and south, before recapture at minimum rates of 0.03–2.00 krn.d^‐1. For females at least, the movement away from North Cape usually occurs at about the time that sexual maturity is attained. Rock lobsters tagged near Cape Reinga moved 3–34 km west at minimum rates of 0.04–0.35 km.d^‐1.

Although the closure of the North Cape grounds to rock lobster fishing restricts the taking of the small number of legal‐sized fish available in the area, the restriction ensures less mortality and damage to the undersized fish due to handling.     

Sperm whales in the western south pacific

The distribution and movements of sperm whales, Physeter catodon Linn., in the western South Pacific (latitudes 30–70° S, longitudes 150E‐150°W) are examined. An undetermined number of catches by nineteenth century American whaleships, 9,720 catches by pelagic fleets in 1961–70, and 427 sightings in 1967 are analysed and correlated with oceanographic data from Australian and New Zealand surveys.

The proportion of females decreases southwards, abruptly at about latitude 44° S in the Tasman Sea, and at about 46–47° S east of New Zealand. Virtually no females occur south of 50° S. The male population density also decreases southwards: the density between 50–70° S appears to be less than 25% of that between 30–50° S. Sperm whales also appear to be less abundant in the eastern part of the region away from the New Zealand plateau, but more data are required.

The pattern of distribution and its seasonal changes probably correlate with vertical temperature gradients of about 5°c in the upper 100 m of water, i.e., optimal conditions for squid schooling. Catch per unit effort in autumn is lower than in spring. A northward population shift in autumn is inferred, based on reduction of available food species and probable temperature tolerances of calves, most of which are born in February and March, towards the end of the southern summer. Some males overwinter in areas where suitable gradients persist, e.g., around the Chatham Islands.

Possibly the summer surface temperature maxima south of the South Island are low enough to inhibit the passage of breeding schools with calves from one side of the New Zealand archipelago to the other. Sperm whales do not pass through Cook Strait normally. Thus, unless considerable mixing of stocks occurs north of New Zealand in winter, there may be two “unit stocks”, one oscillating seasonally between the central Tasman Sea and the Fiji‐Tonga region, and another (probably smaller) between the east coast of the South Island and the region just north of the Chatham Islands.     

基于RDA与GAMs模型的东海近岸海域浮游动物与温盐关系

为进一步探讨东海近岸海域浮游动物季节演替与温盐的变化关系,根据2013年5月(春季)、8月(夏季)和12月(冬季)东海近岸海域3个航次的浮游动物调查资料,利用冗余分析模型分析了优势种与温盐的变化关系,广义加性模型分析了生物多样性参数与温盐之间的关系。结果表明:(1)优势种季节演替较为明显,由春季2种演替成夏季10种,再更替为冬季5种,春季和冬季优势种的种类和生态类群相对单一,夏季较为丰富。(2)优势种时空分布是综合多层环境因子的结果,如春季中华哲水蚤(Calanus sinicus)与表层盐度和底层盐度正相关,夏季与表层温度和底层温度负相关,冬季与表层盐度正相关;春季五角水母(Muggiaea atlantica)与底层温度、底层盐度呈现较好的正相关;夏季盐度是决定暖水性和高温高盐性优势种分布的关键因子,且呈现较强的正相关;冬季真刺唇角水蚤(Labidocera euchaeta)、强壮滨箭虫(Aidanosagitta crassa)与表层温度关系密切,并呈现较强的负相关。(3)春季和冬季香农–威纳指数多样性指数与纬度呈负相关。(4)温度和盐度对生物多样性参数影响显著,但季节上又呈现出差异。     

Influence of ridges on hydrographic parameters in the Southwest Indian Ocean

The objective of the paper is to use the data collected along two meridional sections (45° E and 57°30′ E) during the austral summer (January–March) 2004 to understand the influence of seabed topography across the Madagascar and Southwest Indian Ridges on hydrographic parameters. The study was supplemented by World Ocean Circulation Experiment (WOCE) Conductivity-Temperature-Depth data collected during February–March 1996 along 30° E, as well as Levitus climatology. A southward shift of 2° latitude (between 45° E and 57°30′ E) was recorded for the two predominant frontal structures, i.e., the Agulhas Return Front and Southern Subtropical Front, which is attributed to the influence of seabed topography on hydrographic parameters. No significant spatial variation of these fronts was noted between the 30° E and 45° E meridional sections. Between latitudes 31° S and 42° S, the temperature and salinity structures show deepening over the ridges. The Antarctic Circumpolar Current core was detected between 40°15′ S and 43° S.     

Limnology of Bird Pond,Ross Island,Antarctica

The physical, chemical and biological properties of Bird Pond, Cape Bird, Ross Island, Antarctica (77° 13’ 10” S, 166° 28’ 30” E), were investigated at weekly intervals for 2 months in the summer of 1970–71. The above properties were also investigated over a 24‐h period. Salinity and temperature tolerance of the rotifer Philodina gregaria were investigated in the laboratory at Cape Bird.

Bird Pond is characterised by a high conductivity and chloride ion concentration, and an alkaline pH. It has a water temperature as high as 15°c in mid summer, with the bottom water temperature often 3°c higher than the surface temperature. Diurnal measurements suggest a vertical movement of phytoplankton during a 24‐h period. P. gregaria survives ionic concentrations up to 250 000 g.m^‐3 Na⁺ + Cl^‐, and water temperatures up to 32°c.     

A Numerical Modeling of the Upper and the Intermediate Layer Circulation in the East Sea

Circulation in the upper and the intermediate layer of the East Sea is investigated by using a fine resolution, ocean general circulation model. Proper separation of the East Korean Warm Current from the coast is achieved by adopting the isopycnal mixing, and using the observed heat flux (Hirose et al., 1996) and the realistic wind stress (Na et al., 1992). The simulated surface circulation exhibits a remarkable seasonal variation in the flow patterns of the Nearshore Branch, the East Korean Warm Current and the Cold Currents. East of the Oki Bank, the Nearshore Branch follows the isobath of shelf topography from late winter to spring, while in summer and autumn it meanders offshore. The Nearshore Branch is accompanied by cyclonic and anticyclonic eddies in a fully developed meandering phase. The meandering and the eddy formation of the Nearshore Branch control the interior circulation in the Tsushima Current area. A recirculation gyre is developed in the region of the East Korean Warm Current in spring and grown up to an Ulleung Basin scale in summer. A subsurface water is mixed with the fresh surface water by winter convection in the northeastern coastal region of Korea. The well-mixed low salinity water is transported to the south by the Cold Currents, forming the salinity minimum layer (Intermediate Water) beneath the East Korean Warm Current water. The recirculation gyre redistributes the core water of the salinity minimum layer in the Ulleung Basin. This revised version was published online in August 2006 with corrections to the Cover Date.     

Spatial and temporal distribution of chlorophyll in southern African waters as deduced from ship and satellite measurements and their implications for pelagic fisheries

Information is presented on the distribution of chlorophyll a between the Cunene River (18°S), on the border of South West Africa (Namibia) and Angola, and East London (28°E) on the east coast of South Africa. Spectrophotometric measurements of samples collected during various research cruises and estimates from satellite measurements were used. The coast was divided into a number of oceanographic regions. Spatial and temporal variation of chlorophyll a in the waters off central-northern South West Africa, the Lüderitz region, the South-Western Cape and the Algoa region are discussed in some detail. There was a narrow coastal band of moderate to high chlorophyll a (3 to in excess of 10 mg·m^?3) at the surface between Cape Cross (22°S) and Möwe Point (c. 19°S) throughout most of the year, whereas in much of the area between 23 and 33°S concentrations reached maximum values in autumn. Along the South-Western Cape coast, high concentrations of chlorophyll a were observed in the St Helena Bay area up to 90 km off shore throughout the year, evenly distributed in the upper 30 m. A narrower band of high concentrations of chlorophyll a extended southwards to Cape Agulhas during summer when upwelling was most active. During late summer and autumn a subsurface maximum developed on the Agulhas Bank associated with the thermocline. Low to moderate concentrations were widespread over the entire coastal zone during winter, with strong mixing in the upper 50 — 100 m. A fairly consistent feature of the Algoa region was the presence of moderate concentrations of chlorophyll associated with a wedge-shaped zone of coastal and dynamic upwelling. The implications of the distribution of chlorophyll in time and space are discussed with respect to the distribution and migration of pelagic fish species, particularly anchovy.     

Distribution of Delphinidae (Cetacea) in relation to sea surface temperatures off Eastern and Southern New Zealand

Records of four species of Delphinidae, Delphinus delphis, Lissodelphis peroni, Lagenorhynchus obscurus, and Lagenorhynchus cruciger in waters to the east and south‐east of New Zealand are discussed in relation to surface temperatures.

In this region D. delphis appears to be largely confined north of the Subtropical Convergence and a minimum surface temperature of about 14°c, and near New Zealand from Hawke Bay southward in the warm water of the East Cape Current; L. peroni to the Subtropical Convergence and the subantarctic water to the south of it, between surface temperatures of 9°c and 16°c; L. obscurus to the immediate vicinity of the Subtropical Convergence and surface temperatures in summer of about 14° to 15°c, and L. cruciger across the Antarctic Convergence region, in a surface temperature range of 2° to 9°c.     

Water mass seasonal variability in the Galápagos Archipelago

Three hydrographic surveys were conducted within the Galápagos Archipelago during 2005–2006. The surveys captured the surface properties (<80 m) near the extremes and midpoint of the annual cycle of the mean sea surface temperature (SST) and winds. A cooler SST occurs in boreal summer and fall as the southeast trades strengthen. Current data at 110°W show that this coincides with the Equatorial Undercurrent (EUC) becoming weaker and deeper below a strengthening westward South Equatorial Current (SEC). Opposite conditions are generally found in the spring. Meanwhile, the sea surface salinity (SSS) freshens in late winter/spring when the archipelago receives large rainfalls as the Intertropical Convergence Zone (ITCZ) shifts southward, or in late fall when receiving large influxes from the North Equatorial Countercurrent (NECC). As a result, Tropical Surface Waters (TSW) with salinity (S) <34 fill the archipelago from the late fall through early spring. The SSS becomes saltiest in late spring/early summer as the EUC strengthens, resulting in Equatorial Surface Waters (ESW), S>34, throughout the archipelago. Equatorial Surface Waters are present west of Isabela, where the EUC upwells as it interacts with the Galápagos platform. They also are found east of the archipelago in the cold tongue, which extends westward from South America, and therefore may be advected by the SEC into the archipelago. The upwelling west of Isabela creates a consistently shallow 20 °C isotherm (thermocline), which remains elevated across the archipelago. Linear extrapolation of the thermocline depth along the equator from 110 to 95°W gives a good approximation of the thermocline depth within the archipelago from 92 to 89°W.     

Influence of the monsoon climate on the distribution of neuston copepods in the Northeastern Indian ocean

The horizontal distribution of the near-surface (neuston) copepods of the family Pontellidae was studied on the meridional transects through the central part of the Indian ocean between 12°N and 12°S and in the Bay of Bengal in the summer monsoon period. Eleven species of neuston pontellids were found. The common species Labidocera detruncate and Pontellopsis villosa have the sane high frequencies in the central part of the ocean and in the Bay of Bengal. Some species are rarer in the Bay of Bengal than in the central part of the ocean. In contrast, other species are more frequent in the Bay of Bengal. The special traits of the distribution in the Bay of Bengal coincide with the lower salinity in the bay than in the central ocean. The distribution of some neritic species from the Bay of Bengal to the south is dependent on the intensification of the water translocation to the south in the summer. In the central part of the Indian Ocean, the distribution of the common neustonic pontellids is similar in the periods of the summer and winter monsoons. It is the result of the occupation of the region by the same equatorial water masses.     

Seasonal and tidal variations in the hydrology of Wellington harbour

Observations were made on several hydrological features of Wellington Harbour, New Zealand (41° 16’ S, 174° 51’ E) during 1970 to 1972. These suggest that the harbour is topographically partially isolated from oceanic influences, and that waters within the harbour undergo efficient mixing.

Monthly mean sea‐surface temperatures ranged seasonally between 10.5°c and 18.5°c, and some stratification was observed during summer and winter. Salinities usually ranged from 33.5‰ to 34.5‰, and water transparency by Secchi disc from 3 m to 6 m. Dissolved oxygen content ranged from 96% to 127% saturation, usually exceeding 100% saturation in surface waters.

Under normal discharge conditions during winter, the Hutt River was observed to markedly affect surface temperatures and salinities as far south as Somes Island to a depth of about 5 m.     

Seasonal and inter-annual variability in properties of surface water off Santander,Bay of Biscay, 1991–1995

The annual cycle of temperature, salinity and nutrients of surface waters (up to 100 m depth) was studied from June 1991 to December 1995 in a cross-shelf section over the continental shelf waters off Santander (southern Bay of Biscay). The time series showed that the temperature followed the expected seasonal warming and cooling pattern, which determines a seasonal process of stratification and mixing of the water column. The stratification period occurs annually between May and October in a layer of about 50 m depth from the neritic station beyond to the shelf-break. In the period between November and April the water column remained mixed. During spring and summer low salinity values were found in the surface due to continental runoff and advection from oceanic waters. In late autumn and winter, the salinity pattern was governed by an influx of salty water associated with the poleward current. As in other temperate latitudes, nitrates showed the highest values in winter throughout the water column and the lowest values at the surface during the stratified period. Wind-induced upwelling events were observed mainly in summer, which are characterised by low temperatures (< 12°C), high salinity and nutrient concentrations. The inter-annual variability of temperature showed a warming trend in the upper layers but this sign was not found at 100 m depth. In salinity a decreasing trend was observed throughout the water column, and this feature corresponds to the relaxing of the high salinity anomaly detected in the North Atlantic at the beginning of the 1990s. Both trends were coherent in the cross-shelf section from the coast to the slope.     

阿拉伯海东南海域盐度收支的季节变化

采用SODA海洋同化产品的月平均资料,本文分析了阿拉伯海东南海域表层盐度的季节变化特征,发现局地海面淡水通量不能解释盐度的变化。两个典型区域的表层海水盐度收支分析表明,海洋的平流输送是造成阿拉伯海东南海域盐度冬季降低、夏季升高的主要原因,而淡水通量仅在夏季印度西侧沿岸区域造成盐度降低。冬季,东北季风环流将孟加拉湾北部的低盐水沿同纬度输送到阿拉伯海,然后向北输送,使表层海水盐度降低;夏季,西南季风环流把阿拉伯海西北部的高盐水向南、向东输送,使阿拉伯海东南海域盐度升高。受地理位置因素的影响,阿拉伯海东南海域表层盐度的变化冬季明显强于夏季。     

Seasonal variability of the mixed layer in the central Bay of Bengal and associated changes in nutrients and chlorophyll

Hydrographic data from National Oceanographic Data Center (NODC) and Responsible National Oceanographic Data Centre (RNODC) were used to study the seasonal variability of the mixed layer in the central Bay of Bengal (8–20°N and 87–91°E), while meteorological data from Comprehensive Ocean Atmosphere Data Set (COADS) were used to explore atmospheric forcing responsible for the variability. The observed changes in the mixed-layer depth (MLD) clearly demarcated a distinct north–south regime with 15°N as the limiting latitude. North of this latitude MLD remained shallow (∼20 m) for most of the year without showing any appreciable seasonality. Lack of seasonality suggests that the low-salinity water, which is perennially present in the northern Bay, controls the stability and MLD. The observed winter freshening is driven by the winter rainfall and associated river discharge, which is advected offshore under the prevailing circulation. The resulting stratification was so strong that even a 4 °C cooling in sea-surface temperature (SST) during winter was unable to initiate convective mixing. In contrast, the southern region showed a strong semi-annual variability with deep MLD during summer and winter and a shallow MLD during spring and fall intermonsoons. The shallow MLD in spring and fall results from primary and secondary heating associated with increased incoming solar radiation and lighter winds during this period. The deep mixed layer during summer results from two processes: the increased wind forcing and the intrusion of high-salinity waters of Arabian Sea origin. The high winds associated with summer monsoon initiate greater wind-driven mixing, while the intrusion of high-salinity waters erodes the halocline and weakens the upper-layer stratification of the water column and aids in vertical mixing. The deep MLD in the south during winter was driven by wind-mixing, when the upper water column was comparatively less stable. The deep MLD between 15 and 17°N during March–May cannot be explained in the context of local atmospheric forcing. We show that this is associated with the propagation of Rossby waves from the eastern Bay. We also show that the nitrate and chlorophyll distribution in the upper ocean during spring intermonsoon is strongly coupled to the MLD, whereas during summer river runoff and cold-core eddies appear to play a major role in regulating the nutrients and chlorophyll.     

冬季北太平洋西部上层海洋的热量输送

用海气界面净热量收支和1950－1979年表层水温资料，计算了冬季北太平洋西部上层海洋热通量散度场，指出冬季北太平洋西部黑潮将大量低纬暖水输送到中高纬度海域，在30－35°N最大；亲潮将极地冷水沿千岛群岛向南输送，在45－50°N最大；两者在40°N附近相遇，混合减弱后沿纬向东传。同时用EOF分析方法对热通量散度距平场分型，前3个主要型分别为：黑潮亲潮偶合型、北太平洋海流型和冷平流优势型。最后还揭示了第一主要型与北太平洋副热带高压之间有意义的相关关系。     

The temporal and spatial variability of the Yellow Sea Cold Water Mass in the southeastern Yellow Sea, 2009-2011

The Yellow Sea Cold Water Mass(YSCWM) is one of the important water mass in the Yellow Sea(YS).It is distributed in the lower layer in the Yellow Sea central trough with the temperature less than 10 C and the salinity lower than 33.0.To understand the variability of the YSCWM,the hydrographic data obtained in April and August during 2009–2011 are analyzed in the southeastern Yellow Sea.In August 2011,relatively warm and saline water compared with that in 2009 and 2010 was detected in the lower layer in the Yellow Sea central area.Although the typhoon passed before the cruise,the salinity in the Yellow Sea central trough is much higher than the previous season.It means that the saline event cannot be explained by the typhoon but only by the intrusion of saline water during the previous winter.In April 2011,actually,warm and saline water(T >10 C,S >34) was observed in the deepest water depth of the southeastern area of the Yellow Sea.The wind data show that the northerly wind in 2011 winter is stronger than in 2009 and 2010 winter season.The strong northerly wind can trigger the intrusion of warm and saline Yellow Sea Warm Current.Therefore,it is proposed that the strong northerly wind in winter season leads to the intrusion of the Yellow Sea Warm Current into the Yellow Sea central trough and influenced a variability of the YSCWM in summer.     

Wind- and density-driven circulation in a bay on the Sanriku ria coast,Japan: study of Shizugawa Bay facing the Pacific Ocean

Flow fields in Shizugawa Bay on the Sanriku ria coast, which faces the Pacific Ocean, were investigated using hydrographic observations for the purpose of understanding oceanographic conditions and the process of water exchanges in the bay after the 2011 earthquake off the Pacific coast of Tohoku. In spring to summer, density-driven surface outflow is part of estuarine circulation and is induced by a pressure gradient force under larger longitudinal gradients in density along with lower salinity water in the innermost part of the bay, regardless of wind forcing. In winter to summer, another density-driven current with a thermal structure is induced by a pressure gradient force under the smaller longitudinal density gradients in calm wind conditions. Particularly in winter, Tsugaru Warm Current water can be transported in the surface layer inside the bay. Wind-driven bay-scale circulation with downwind and upwind currents in the surface and deeper layers, respectively, is induced by strong longitudinal wind forcing under the smaller longitudinal density gradients, irrespective of season. Particularly in fall to spring, this circulation can cause the intrusions of oceanic water associated with Oyashio water and Tsugaru Warm Current water in the deeper layer. These results suggest that wind- and density-driven currents can produce the active exchange of water from inside and outside the bay throughout the year.     

Surface distribution of alkalinity and specific alkalinity and their application to water mass tracing in Kuroshio area of the East China Sea

Surface distribution and seasonal variation of alkalinity and specific alkalinity in Kuroshio area of the East ChinaSea and their application to the water mass tracing are discussed in this paper. Results show a distinct seasonal variation of the alkalinity, which is concerned with the process of vertical mixing. Different specific alkalinity in various water masses has been found. On the basis of the difference of the specific alkalinity and the distribution of alkalinity, two water fronts in summer season, located at 27°-30°N and 124°-1 27°E, (Ⅰ), and at the northern waters about one latitude from the Taiwan Island, (Ⅱ); one in winter season at about one longitude from coast of mainland of China and 26°-30°N were found. In summer season, about 1-2 longitudes eastward shift of front (Ⅰ) is found by comparison of data in May and August. And the high alkalinity of the northern East China Sea in summer season may be caused by the Huanghe River runoff flowing southward along with the Huanghai Sea