Role of the <Emphasis Type="Italic">Noctiluca scintillans</Emphasis> population in the trophic dynamics of the Black Sea plankton over the spring period

Noctiluca scintillans is a common and numerous component of the heterotrophic plankton living in the Black Sea. It can play a significant role in the trophic dynamics of the pelagial community. The ingestion rate for the Black Sea Noctiluca is experimentally measured in this article, and its influence on the plankton community over the spring period is estimated. The average grazing of phytoplankton by the N. scintillans population made up about 0.8% in March. In local swarms, it was up to 11%. Noctiluca grazed 4.6% of the primary production per day in June. The grazing of Calanus euxinus eggs by the Noctiluca population varied from 1% to 42% in March. Then, it was 16% in April and 23% in June. The grazing of Acartia clausi eggs was from 1% to 7% in March–April (up to 80% in Noctiluca swarms), from 60% to 817% in May, and 45% in June. The grazing of Calanus faecal pellets was less than 1% in March–April and more than 20% in the beginning of June. It is the first time when the cumulative daily ration (subject to its various food components) for N. scintillans has been measured. The size of the ration was significantly higher than the energy expenditures on metabolism both in March (0.21 μg of C/ind/day) and in the beginning of June (0.28 μg of C/ind/day). Thus, the rapid growth of the population was enabled.     

Symbiodinium diversity within Acropora muricata and the surrounding environment

Several long‐term studies have monitored populations of algal symbionts, Symbiodinium sp., in coral hosts over different temporal and spatial scales, and among multiple host species. The extension of these studies to include environmental pools of algal symbionts from sources such as the water column, sediments, free‐floating mucus mats and those settling on biofilms has only been studied by a few, yet has the potential to enhance our understanding of the dynamics and controls on symbiont populations. Adaptive changes in the coral symbiont complement rely either on the uptake of new strains from the environment or population expansion of rarer strains in the existing symbiont population. The relative scope for these alternative pathways of uptake is unknown. This study therefore examined spatial changes in Symbiodinium clades within the water column at two different time periods and compared these with other environmental pools (biofilms, sediments, and mucus mats) and those within the dominant reef‐building species at the study site, Acropora muricata. A diversity of algal symbiont clades were detected in environmental pools, with specific clades associated with different habitats. At an island scale, there was significant variation in clade composition between sites separated by 0.5–7 km, a result which was repeated for both sample periods encompassing different seasons (March 2009 and August 2010). Although no single environmental pool contained a Symbiodinium complement comparable to that of the host coral species investigated, the dominant coral Symbiodinium were available in combinations of the environmental pools, indicating that the coral has the potential to obtain its symbionts from a variety of environmental sources.     

南海大鹏湾海洋卡盾藻赤潮发生的环境背景

根据１９９１年２－３月，大鹏湾盐田水域的理化、水文、气象、海况的动态变化和大鹏湾底泥中发现海洋卡盾藻孢囊的事实，从生态学的角度分析并提出了１９９１年３月２０－２１日发生在大鹏湾盐田水域的海洋卡盾藻赤潮形成过程和机理。分析结果认为，此次赤潮应从３月７－１０日的水温急升而引发的孢囊一齐萌芽开始，此后在东南风引起的表层风海流作用下，营养细胞逐渐在湾西北部的盐田水域聚集，而１６－１９日水 营养盐和金属元素     

大鹏湾夜光藻种群的季节变化和分布特征

于１９９０年３月－１９９２年６月对中国南海大鹏湾盐田附近海域的夜光藻种群动态及时空分布进行了综合调查，结果表明，夜光藻种群的出现期间一般为每年的１－６月，最早是１９９１年的１２月，娄量高峰期为３－５月，种群密度的波动极为显著；调查期间共发生８次赤潮，且都发生在３月初至５月初；大鹏湾夜光藻赤潮的发生特点是，赤潮的发生和消失突然，持续时间短，一般不超过３ｄ。     

大鹏湾夜光藻种群的季节变化和分布特征

于1990年3月－1992年6月对中国南海大鹏湾盐田附近海域的夜光藻种群动态及时空分布进行综合调查。结果表明，夜光藻种群的出现期间一般为每年的1－6月，最早是1991年的12月，数量高峰期为3－5月，种群密度的波动极为显著；调查期间共发生8次赤潮，且都发生在3月初至5月初；大鹏湾夜光藻赤潮的发生特点是，赤潮的发生和消失突然，持续时间短，一般不超过3d；调查海域夜光藻种群的空间分布模式为近岸的高于中央水域的，表面的高于底层的。     

Diet composition of New Zealand’s endemic rough skate,Zearaja nasuta

Diet analysis can provide an insight into the structure and function of an ecosystem, and can be used in ecosystem-based frameworks to inform management and conservation decisions. Diet composition of rough skate (Zearaja nausta) from the south east coast of New Zealand, was investigated for the first time. We examined 35 stomachs from three trawls between March and June 2017. Prey importance was assessed by a prey specific index of relative importance (PSIRI). This population of rough skates (n?=?32) was found to be specialised feeders, primarily preying on one species, Nectocarcinus antarcticus. This study provides the first insight into rough skate trophic interactions in the surrounding marine community.     

Variations in tidal response of the medium in the spatiotemporal neighborhood of catastrophic earthquake in Japan

The predictability of catastrophic earthquakes according to data on time variations in tidal response is discussed. We present the results of a harmonic analysis of (1) a one-year record of tide-gauge observations with the use of two long-term vertical seismometers at the MAJO station on Honshu Island near the epicenter of the M _w = 9 catastrophic earthquake of March 11, 2011, and (2) a 0.5-year record of horizontal pendulum observations at the ERM station near Hokkaido Island from March 13, 2010, to March 12, 2011, and from April 26, 2010, to August 3, 2010, respectively. The relative changes in the tidal amplitudes are found to be about 3 and 4%. The identification of distinct prognostic attributes awaits much more representative spatiotemporal statistics. These results can be adequately and reliably interpreted by analyzing “background” variations in the tidal amplitudes at these stations and, in particular, their possible seasonal variations. This requires at least several years of observations.     

Growth and Production in Posidonia Oceanica (L.) Delile*

Abstract. In situ investigations of growth and production in a stand of Posidonia oceanica (L.) DELILE at a depth of 4 m at Ischia (Gulf of Naples) were carried out over two growing seasons. Posidonia starts to grow in August and an average bundle produces ten leaves in increasing time intervals until May. Growth curves for the leaves are given. Maximum leaf standing crop is in May with 1300 g dry weight per m^-2, leaf area index at this time reaches 22 m² m^-2. Leaf net productivity is highest in March with 12 g dry weight per m² per day. Annual leaf production is estimated as 3110 g dry weight per m², “underground” production as 115 g dry weight per m². About half the leaf production is exported from the system. Adaptive strategies of the growth and production pattern are discussed.     

Mean current velocity measurement from a movable base

This paper discusses the possibility of measurement of the current velocity vector characteristics averaged over the time of continuous regular down-up probings from a moving carrier. The measurements can be carried out either from a moving vessel or from a helicopter, floating on or hovering above the sea surface. As an illustration for the suggested technique,in situ observations compiled by a free-component (±XYZ) VEGA-3 probe in the Guiana current region in March 1990 are provided. Comparison of the results with buoy data shows good agreement within the accuracy limits of the instruments employed.Translated by Vladimir A. Puchkin.     

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

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.     

莱州湾拟哲水蚤Paracalanus sp.发育期丰度组成和个体大小季节变化

拟哲水蚤是莱州湾桡足类中周年出现的优势种;是上层鱼类幼鱼早期开口饵料的重要贡献者;掌握其种群动态分布特点;有利于了解湾内生物环境状况、次级生产力生产水平。基于2011年5月至20 12年4月采集的浮游生物资料的分析结果显示;莱州湾拟哲水蚤的发育期丰度组成和个体大小均表现了明显的季节变化。调查季节中;4-6月以成体居多;其他季节以桡足幼体CⅢ-CⅤ较多;其中10-11月和3月主要由后期桡足幼体CⅣ和CⅤ期构成。成体中以雌体为主导;雌/雄比介于1.46~9.62;该比值在3-4月最低;10-11月最高。拟哲水蚤各期桡足幼体和成体个体大小以4-5月最大、8月最小;并与水温表现出明显的负相关。拟哲水蚤桡足幼体和成体的总生物量月变化与丰度变化相同;即以8月值最高;3-5月值最低;月均值为2.69 mg/m3（以碳计）;日生产力估算值为0.74 mg/（m3·d）（以碳计）。由上述结果;推测莱州湾拟哲水蚤的种群结构周年变化主要可分3个阶段;4-6月是莱州湾拟哲水蚤开始繁殖期;7-8月为种群数量快速增长期;9月之后为种群增长相对停滞期。     

Exploring interactions among intertidal macrozoobenthos of the Dutch Wadden Sea using population growth models

Using data taken from three long-term monitoring programs, we modelled the population dynamics of 13 common macrozoobenthic species of the Balgzand, an approximately 50 km² intertidal area in the Dutch part of the Wadden Sea. In order to identify likely interactions among species, while accounting as much as possible for other factors influencing population dynamics, models included both ‘environmental’ (water temperature, and phytoplankton concentration) and ‘biological’ (biomass of potentially interacting species) variables. This approach appeared to be effective at identifying certain types of interactions acting over relatively short time-frames, such as predation and competition for food. Among the species we considered, the strongest effects of this kind appeared to be from what we presume to be predation by Nephtys hombergii, and from competition for food among bivalves. Several of the strongest results of our analysis corroborated expectations derived from previous small-scale surveys or experimental studies, but there were also a number of highly significant results indicating possible interactions which were not immediately explicable, including the apparent positive effect of Macoma balthica on Arenicola marina, and the apparent negative effect of Nephtys hombergii on Mya arenaria. Our results also suggest that year to year changes in Cerastoderma edule and Arenicola marina populations did not have substantial and widespread influences on the population dynamics of the majority of other common infauna, which is not to deny the likely critical importance of recruitment effects and biogenic transformation of the intertidal environment by these species over longer time frames. Our modelling approach could be applied to other long-term data sets, and will become more useful as longer time series become available.     

Entanglement of pinnipeds at Marion Island

During the period April 1991–March 1996, 10 entangled Antarctic fur seals Arctocephalus gazella, 28 entangled Subantarctic fur seals A. tropicalis and one entangled southern elephant seal Mirounga leonina were observed at Marion Island, Southern Ocean. Entanglement of fur seals was estimated at between 0.01 and 0.15% of the combined population of both species.     

Ecology of the marine cladoceran Penilia avirostris Dana in Tolo Harbour, Hong Kong

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南海大鹏湾夜光藻种群在其生态群落中的地位和功能

分析了１９９１年上半年南海大鹏湾盐田水域夜光菏和浮游动、植物之间的种群动态关系，结果表明，在春季高峰期３月至５月初，调查海域共出现１２个夜光藻和浮游动、植物高峰。其中，以发生４次赤潮的夜光藻种群占主导地位，其次是枝角类的鸟啄尖头蚤，其最高数量高达９６２３８ｉｎｄ／ｍ＾３。相比之下，在夜光藻和枝角类岛啄尖头捕食压力的影响下，浮游植物的春季高峰并不显著。调查结果表明夜光藻的过度繁殖，不但对产浮游性卵的     

Abundance of fin whales (Balaenoptera physalus) in the north-western Mediterranean Sea,using photo-identification and microsatellite genotyping

The Mediterranean fin whale population, Balaenoptera physalus, is resident, with almost no exchanges with the Atlantic population. The entire population was estimated at 1300 or 13,300 individuals by a recent project depending on the platform used. This disparity shows the importance of long-term monitoring with a unique protocol of survey. Capture-recapture approaches using dorsal photographs and genetic identity collections over a 10 years period were used to estimate the abundance of the north-western Mediterranean fin whale. We identified 332 individuals using photographs and 470 using genotypes, with a total of 546 individuals identified between 2008 and 2019, when some whales were double-marked. The inter-annual percentage of recapture varied between 15% and 17% respectively for genotypes and photographs methods. Using Cormack-Jolly-Seber models, the abundance of fin whales in the north-western Mediterranean is estimated at 1295 individuals (95% CI: 1116–1474) with a survival probability of 0.945 (95% CI: 0.690–0.993) from genotypes. Abundance estimates from combined collections (photographs and genotypes) and corrected photograph estimates were similar to the genetic ones. Future studies might prioritize the genetic approach which is the least biased and with a narrower confidence interval. The genetic abundance estimates show relative stability over time, when compared to 1990 estimates, and should be included in future conservation actions.     

Environmental Factors Affecting the Occurrence and Production of the Spring Phytoplankton Bloom in Funka Bay, Japan

The concentration of nutrients was measured during the spring phytoplankton bloom in Funka Bay over a 5-year period (1988–92). During the winter mixing period, nutrient concentrations were similar in every year except in 1990 when a high concentration of silicate was observed. There was interannual variation in the onset of the bloom, presumably depending on the stability of the water column. The bloom developed in early March when the Oyashio water (OW), which has a lower density than the existing winter water, flowed into the bay and the pycnocline formed near the bottom of the euphotic zone. In this case, high chl a was found only in the euphotic zone and nutrient utilization was limited to this zone. In the year when the inflow of OW was not observed by April, the bloom took place at the end of March without strong stratification and high chl a was found in the whole water column, accompanied by a decrease in nutrients. Interannual differences were found not only at the beginning of the decrease, but also in the thickness of the layer which showed a decrease in nutrients. Primary production from the beginning to the end of the spring bloom was estimated from the nutrient budget before and after the spring bloom. The integrated production over the spring bloom period ranged from 25 to 73 g C m^-2, which accounts for 19–56% of the annual production in this bay. We found that the timing of the bloom was strongly dependent on the inflow of OW, but the amount of production was not clearly related to this timing.     

Population structure of the thornback ray (Raja clavata L.) in British waters

Prior to the 1950s, thornback ray (Raja clavata L.) was common and widely distributed in the seas of Northwest Europe. Since then, it has decreased in abundance and geographic range due to over-fishing. The sustainability of ray populations is of concern to fisheries management because their slow growth rate, late maturity and low fecundity make them susceptible to exploitation as victims of by-catch. We investigated the population genetic structure of thornback rays from 14 locations in the southern North Sea, English Channel and Irish Sea. Adults comprised < 4% of the total sampling despite heavy sampling effort over 47 hauls; thus our results apply mainly to sexually immature individuals. Using five microsatellite loci, weak but significant population differentiation was detected with a global F_ST = 0.013 (P < 0.001). Pairwise F_st was significant for 75 out of 171 comparisons. Although earlier tagging studies suggest restricted foraging distances from home areas, the absence of genetic differentiation between some distant populations suggests that a substantial fraction of individuals migrate over wide areas. Autumn/winter locations appear to have a lower level of differentiation than spring/summer, which could be due to seasonal migration. Management and conservation of thornback ray populations will be challenging as population structure appears to be dynamic in space and time.     

Planktonic stages of Maurolicus muelleri (Teleostei Sternoptychidae) in New Zealand waters

The seasonality and distribution, abundance, and hydrological affinities of the planktonic stages of the sternoptychid Maurolicus muelleri (Grnelin, 1788) are described for the New Zealand region. Spawning occurred from August to March, and the planktonic stages were widespread around New Zealand. Spawning probably takes place around midday at depths greater than 250 m. Eggs and larval stages were present over temperature ranges of 9.0–15.5°c and 13–22°c respectively.     

Role of dissolved silicate in the occurrence of a phytoplankton bloom

The spring bloom of phytoplankton was studied in March in Funka Bay, Japan, to test the Tsunogai (1979)'s hypothesis regarding the role of silicate in the bloom. The hypothesis comprises two parts. 1) Diatoms are predominant when all the physical and chemical conditions are adequate for plankton growth. 2) Since the Si:P ratio of the diatom body is usually much larger than that of sea water, flagellates (non-siliceous phytoplankton) replace diatoms after dissolved silicate in the sea water has been almost completely consumed by diatoms. At the end of the bloom in late March phosphate still remained in the water but silicate was exhausted and the main species of phytoplankton changed from diatoms to flagellates. Grazing pressure by zooplankton at this time was not so great. A model using the data on assimilation rates of silicate showed a dramatic change of silicate uptake in late March. Poison in scallops caused byProtogonyaulux sp. (dinoflagellates) rapidly increased from mid-April at all stations along the coast of Funka Bay. All of these findings support Tsunogai's hypothesis.