珠江口伶仃洋海域底层游泳动物的季节变化

珠江口伶仃洋海域是渔业资源的重要栖息地,近年来由于人类活动的加剧导致生态环境质量下降。为进一步了解栖息环境恶化对渔业资源的影响,于2009年8月至2010年4月采用底拖网在珠江口伶仃洋海域进行了游泳动物4个季节的调查。共鉴定游泳动物92种,其中鱼类54种,甲壳类32种和头足类6种。游泳动物种数夏季最高,为52种,春季最低,仅35种,春、夏季和冬、春季种类季节更替显著。优势种组成较为稳定,以日本蟳(Charybdis japonica)、黑斑口虾蛄(Oratosquilla kempi)和棘头梅童鱼(Collichthys lucidus)为主要优势种,其中日本蟳为全年优势种,平均尾数密度占总密度的8.07%～26.22%。游泳动物资源密度和尾数密度季节变化趋势一致,均为夏季最高,秋季和春季次之,冬季最低。珠江口伶仃洋海域温度和盐度有明显的季节变化,夏季和秋季温度较高,盐度较低,冬季和春季温度较低,而盐度较高。温度是伶仃洋海域游泳动物种类和数量季节变化的主要因子。与历史资料比较,珠江口主要经济鱼、虾类出现小型化趋势。     

DISTRIBUTION OF DIATOMS IN THE PLANKTON OF YAQUINA ESTUARY,OREGON1

The distributional patterns of diatoms in the plankton of the Yaqnina Estuary, Oregon, were, investigated and related to selected climatic and hydrographic factors. Distribution was strongly influenced by seasonal patterns of rainfall resulting in the introduction of a large volume of fresh water into the estuary during fall and winter. Plankton assemblages in spring, summer and fall had fewer diatom species and exhibited a more rapid rate of change in species composition than in winter. Winter assemblages were further characterized by many pennate diatoms, apparently dislodged from the benthos during periods of high freshwater discharge and silt loads. A statistical measure of community difference indicated an increase in taxonomic homogeneity among assemblages throughout the estuary with the onset of the rainy season in late fall and a gradual transition to a more heterogeneous system again during late spring. Canonical correlation ordered 20 prominent diatom taxa along the salinity gradient and identified possible relationships among certain taxa and selected environmental variables, namely visible light energy and temperature. Redundancy in the species data given the environmental data was only 40%, emphasizing the difficulty in demonstrating a quantitive relationship between plankton dynamics in the field and concurrent measurements of chemical and physical variables.     

大陈岛礁海域甲壳类群落结构时空格局及其环境驱动

为探究局地尺度下近岸岛礁海域之多变水体环境、极高空间异质性对生物群落的影响,于2020—2021年4个季度在大陈岛礁海域底拖网采样,利用等级聚类(cluster)、非度量多维标度(NMDS)等多元统计方法分析甲壳类群落结构的时空格局,并整合温度、盐度、深度等环境因子进行冗余分析(RDA)以解析影响因素,同时利用丰度生物量曲线(ABC)及W统计量评估群落稳态。结果显示：全年共采集甲壳类53种,隶属2目13科29属,虾类占总种类数的56.60%,种类数秋季(43种)>冬季(41种)>春季(31种)>夏季(26种)。优势种的季节更替明显,夏秋季以哈氏仿对虾(Parapenaeopsis hardwickii)、中华管鞭虾(Solenocera crassicornis)和三疣梭子蟹(Portunus trituberculatus)为代表的中大型经济种为主,冬春季则以双斑蟳(Charybdis bimaculata)和细巧仿对虾(Parapenaeopsis tenella)为代表的小个体饵料种为主,口虾蛄(Oratosquilla oratotria)在各个季节皆为优势种...     

Seasonal pattern of zooplankton communities and their environmental response in subtropical maritime channels systems in the Bay of Bengal,Bangladesh

Zooplankton are a primary component of aquatic food chain and play an important role in the functioning of aquatic food webs. Seasonal variation in community structures of zooplankton and potential environmental drivers were studied, during a 1-year cycle (summer 2015 – spring 2016) in subtropical maritime channels systems in the Bay of Bengal, coastal waters in Bangladesh. A total of 32 species representing 25 families, 13 orders and 15 taxonomic groups were identified. Of these species, 23 distributed in all four season of which 8 were dominant species with high contributions of the total communities. Species number was peaked in autumn and fell in summer while maximum abundance was in the winter and minimum in summer. Multivariate analyses showed that there was a clear seasonal shift in zooplankton community structures in relation with environmental conditions. Species diversity and evenness peaked in summer while the high value of species richness was found in autumn. Multivariate correlation (RELATE) and BIO-ENV analysis demonstrated that seasonal variation in community patterns was significantly correlated with temporal shift of environmental conditions and that variation mainly driven by water transparency, salinity, DO, TSS and nutrients. Thus, this finding implies that the zooplankton community represented a clear seasonal shift shaped by environmental drivers in subtropical channels systems.     

长江口低盐淡水区潮间带鱼类群落结构季节及半月相变化

基于2006年春（5月）、夏（7月）、秋（9月下旬）和冬季（2月）对长江口低盐淡水区水域进行的潮间带鱼类调查结果,分析了鱼类种类及丰度的半月相及其季节变化. 结果表明：长江口低盐淡水区水域潮间带鱼类共有53种;其中鲤科鱼类最多,虾虎鱼科次之,其他科较少. 2顶网具渔获物的鱼类种类和丰度均以春、夏、秋季较高,冬季最低.各个季节的平均种类数和平均丰度均为小潮期小于大潮期. Shannon-Weaver指数（H′）在一个潮周期内的波动幅度较大,且小潮期H′值略低于大潮期. 对鱼类种类丰度进行聚类分析发现,冬季鱼类聚成一组,春、夏和秋季聚成一组. 从整年的情况来看,潮间带鱼类的丰度变化与水温的相关性最高;与潮高的相关性次之;而与盐度的相关性最小.     

Population dynamics of a diverse rodent assemblage in mixed grass-shrub habitat, southeastern Colorado, 1995-2000

We followed seasonal and year-to-year population dynamics for a diverse rodent assemblage in a short-grass prairie ecosystem in southeastern Colorado (USA) for 6 yr. We captured 2,798 individual rodents (range, one to 812 individuals per species) belonging to 19 species. The two most common species, deer mice (Peromyscus maniculatus) and western harvest mice (Reithrodontomys megalotis), generally had population peaks in winter and nadirs in summer; several other murid species demonstrated autumn peaks and spring nadirs; heteromyids were infrequently captured in winter, and populations generally peaked in summer or autumn. Inter-annual trends indicated an interactive effect between temperature and precipitation. Conditions associated with low rodent populations or population declines were high precipitation during cold periods (autumn and winter) and low precipitation during warm periods (spring and summer). Severity of adverse effects varied by species. Heteromyids, for example, were apparently not negatively affected by the hot, dry spring and summer of 2000. Cross-correlations for the temporal series of relative population abundances between species pairs (which are affected by both seasonal and interannual population dynamics) revealed positive associations among most murids and among most heteromyids, but there were negative associations between murids and heteromyids. These results have important implications for those attempting to model population dynamics of rodent populations for purposes of predicting disease risk.     

Fish larvae assemblages in the Gulf of California

The distributional diversity and assemblages of fish larvae in the Gulf of California indicated two main seasonal stages and two transitional periods: in winter, the tropical water mass is confined to the south‐east portion of the mouth of the Gulf and larval fish assemblages are dominated by subtropical and temperate‐subarctic species; in summer; tropical water invades the Gulf and assemblages are dominated by tropical species. Both seasonal stages are separated by transitional periods coinciding with strong latitudinal temperature gradients. During the autumn and spring transitional periods, the Gulf of California splits into three regions: a northern region where temperate and subarctic species spawn from autumn to spring, a southern region dominated by tropical and subtropical species year round and a central region where tropical and temperate assemblages merge. Seasonal changes in the location of the regions, as well as the borders between them, show expansion and contraction of the northern and southern faunas related to the general oceanic circulation patterns during the year.     

海南岛西北沿岸海域浮游桡足类的分布及群落特征

为了解昌江沿岸海域生态系统的现状, 探讨海域环境因素对浮游动物的生存环境造成的影响。本文根据2008年11月至2009年7月在海南西部昌江沿岸水域21个测站、4个季度月调查所获的浮游桡足类样品数据, 对该海域浮游桡足类群落结构、分布、季节变化及影响因素进行了分析。本调查共鉴定出桡足类44种, 隶属4目17科24属, 其中秋季25种, 冬季23种, 春季22种, 夏季23种。本次调查共发现优势种6种, 分别是微刺哲水蚤(Canthocalanus pauper)、亚强次真哲水蚤(Subeucalanus subcrassus)、锥形宽水蚤(Temora turbinata)、刺尾纺锤水蚤(Acartia spinicauda)、椭形长足水蚤(Calanopia elliptica)和精致真刺水蚤(Euchaeta concinna), 优势种以近岸暖水种居多。浮游桡足类丰度季节变化明显: 冬季最高, 达409 ind./m³; 秋季次之, 为144 ind./m³, 春季为55 ind./m³, 夏季最低仅为17 ind./m³。其丰度的平面分布显示: 秋、冬季节分别在海区中部和南部形成明显密集区, 春、夏季节则大致呈现由外海向近岸逐渐递减的趋势。浮游桡足类的多样性指数(H')表现为夏季>春季>秋季>冬季, 春、夏季的均匀度指数(J')明显高于秋、冬季。本调查反映出该海区的桡足类群落具有热带—亚热带区系特征, 种类组成季节更替明显, 桡足类种群受海域水温和硅藻的影响明显, 受盐度影响不明显。     

渤海水母类生态的初步研究——种类组成、数量分布与季节变化

水母类是海洋生态系统中非常重要的一个类群。根据 1 959年以来在渤海进行的几次较为全面的调查资料 ,对渤海水母类的种类组成、数量分布与季节变化作了较为详细的研究。共记录到水母类 4 1种 ,其中水螅水母 35种 ,钵水母 4种 ,栉水母 2种。主要以近岸低盐类型为主 ,高盐种类少并且出现时间短。渤海水母类密度的季节变化有 3个高峰 ,出现在冬季 ,夏季和秋季 ,分别由八斑芮氏水母、酒杯水母属、和平水母属、五角水母构成。渤海水母类的分布具有一定的季节特点 ,冬季和夏季以莱州湾密度最高 ,春季为渤海湾最高 ,秋季为中央海区最高。辽东湾水母类的密度在各个季节都不算高     

Seasonal variability of free amino acids in two marine bivalves, Macoma balthica and Mytilus spp., in relation to environmental and physiological factors

The seasonal variability of the intracellular free amino acid (FAA) concentration was studied in 5 Macoma balthica populations and 7 Mytilus spp. populations along their European distribution. Because of the well known physiological role of FAA as organic osmolytes for salinity induced cell volume regulation in marine osmoconformers, FAA variations were compared in bivalve populations that were exposed to high vs. low intraannual salinity fluctuations. In general, seasonal FAA variations were more pronounced in M. balthica than in Mytilus spp. In both bivalve taxa from different locations in the Baltic Sea, highest FAA concentrations were found in autumn and winter and low FAA concentrations were measured in summer. Seasonal patterns were less pronounced in both taxa at locations with constant salinity conditions. In contrast to Baltic Sea populations, Atlantic and Mediterranean bivalves showed high FAA concentrations in summer and low values in winter, regardless of seasonal salinity fluctuations. Significant seasonal FAA variations at locations with constant salinity conditions showed that salinity appeared not to be the main factor in determining FAA concentrations. The seasonal patterns of the main FAA pool components, i.e. alanine, glycine and taurine, are discussed in the context of seasonal variations in environmental factors (salinity, temperature) and physiological state (glycogen content, reproductive stage).     

Spatial and temporal variations in nematode assemblages in tropical seagrass sediments

The changes in the community dynamics of infaunal nematodes associated with tropical Australian intertidal seagrasses at 4 estuarine sites were investigated through 3 seasons (autumn, winter and spring). Nematode densities were highest in winter in all but one of the sites, ranging from 1971 to 3084 inds./10 cm², with one site showing a highest density of 3411 inds./10 cm² in spring. Multiple regression revealed significant correlations between nematode density peaks and seasonal changes in temperature, salinity and surface seagrass cover. Non-metric Multi-Dimensional Scaling revealed that the communities were characterised by relatively low within-site spatial variability but relatively high temporal variability through the three seasons. This temporal variability was largely due to significant increases in abundance of epistrate-feeding species in winter and spring. An investigation of the dominant epistrate-feeding nematodes revealed that predominantly infaunal species were responsible for overall winter and spring density increases. This study provides further evidence of the role played by temperature in regulating tropical, intertidal meiobenthic communities but also indirectly provides evidence of micro-scale seagrass canopy effects (micro-algal supply and availability) that may further enhance the impacts of these larger-scale seasonal environmental changes on the infaunal nematode community.     

渤海浮游动物群落生态特点 Ⅱ.桡足类数量分布及变动

用1959年全国海洋普查浮游动物中网样品分析渤海浮游动物。尤其是中小型浮游动物的数量分布及变动特点。结果表明,渤海浮游动物全年平均丰度为3841ind／m^3,最大33756ind/m^3,最小6．5ind／m^3。其中桡足类年平均密度为3413ind／m^3,是数量的主要构成者。渤海浮游动物主要的高峰期出现在夏季,此外春、秋两季各自有一个小的高峰。春季峰主要是由双毛纺锤水蚤(Acartia bifilosa)的大量繁殖造成,秋季峰主要是由拟长腹剑水蚤(Oithona similis)构成。夏季峰是由于小拟哲水蚤(Paraclanus parvus)、强额拟哲水蚤(Paracalanus crassirostris)、拟长腹剑水蚤等多种桡足类和一些幼虫大量繁殖造成。渤海浮游动物季节演替比较明显。双毛纺锤水蚤、墨氏胸刺水蚤(Centropages mcmmurrichi)和中华哲水蚤(Calanus sinicus)是春季的优势种;小拟哲水蚤、拟长腹剑水蚤、近缘大眼剑水蚤(Corycaeus affinis)和太平洋纺锤水蚤（Acartia pacifica)是夏季的优势种;拟长腹剑水蚤、真刺唇角水蚤（Lubidocera euchaeta)等是秋季的优势种。数量的水平分布同温度的水平分布趋势基本一致。同盐度趋势相反。     

舟山渔场及邻近海域浮游动物数量分布特征

依据2006年8月(夏)、2007年1月(冬)、5月(春)和11月(秋)在舟山渔场及其邻近海域(29°30′-31°30′N,124°30′E以西)开展海洋生态系统综合调查时,用浅水Ⅰ型浮游生物网采集的浮游动物样本资料,分析了浮游动物总丰度及中华哲水蚤(Calanus sinicus)、精致真刺水蚤(Euchaeta concinna)、百陶箭虫(Sagitta bedoti)、肥胖箭虫(Sagitta enflata)等主要种类的数量分布和季节变化特征。结果表明:调查海域浮游动物平均丰度季节变化明显,春季(555.87ind./m3)夏季(270.87ind./m3)秋季(138.39ind./m3)冬季(127.70ind./m3);其水平分布呈现南部高、北部低的特点。中华哲水蚤为广温广盐种,春季数量最大且分布均匀,大部分海域丰度≥100.00ind./m3;夏季丰度急剧下降,主要分布在30°00′N以南海域;秋、冬季丰度较低,无明显高密集区。精致真刺水蚤为热带种,以夏、冬季丰度较高,主要分布在沿岸水与外海高盐水交汇区和调查海域的南北两端;春、秋季丰度较低且分布均匀。百陶箭虫、肥胖箭虫分别属于暖水种和热带大洋性种,冬、春季丰度都很低,无明显密集区,夏、秋季丰度较大。百陶箭虫主要分布在盐度梯度较大、外海高盐水与沿岸水的交汇区,肥胖箭虫则主要分布在外海高盐水与沿岸水交汇区的靠高温高盐水一侧,其分布与外海高温高盐水的消长有密切关系,可作为暖流指示种。温盐和水系消长变化是影响舟山渔场及邻近海域浮游动物丰度水平分布的重要因素。     

SEASONAL PRIMARY PRODUCTION OF UNDERSTORY RHODOPHYTA IN AN UPWELLING SYSTEM1

The in situ primary production of three common under-story members of the Rhodophyta in South African west coast kelp beds was determined monthly for a year using dissolved oxygen techniques. Strong seasonal patterns of photosynthesis and respiration were evident in all three species. Net photosynthesis of all three species was greatest in spring (October) and lowest in winter (June). Increasing photosynthesis in late winter coincided with increasing ambient irradiance and photoperiod, whereas decreasing photosynthesis in summer was not explained by changes in the environmental parameters measured. We suggest that this may he due to an innate pattern related to some other seasonal plant activity such as reproduction. Seasonal P_max and I_k values reveal that the obligate understory species, B. prolifera and E. obtusa, are shade-adapted whereas G. radula, a low intertidal and shallow subtidal dominant, is sun-adapted. Low C: X ratios consistent with a high nutrient environment and high rates of productivity were found in all three species. Net photosynthesis to respiration (Pn:R) ratios were fairly constant for B. prolifera and E. obtusa, implying that then photosynthetic processes were governed more by seasonal variations in irradiance than by instantaneous light availability. The Pn: R ratio of G. radula was variable, suggesting that this species is more responsive to rapid fluctuations in irradiance and may therefore be adapted for rapid growth during periods of high irradiance.     

大亚湾大辣甲水域溶解无机碳垂直分布特征及季节动态

于2007年10月～2008年9月进行了4个季节的垂直采样监测,对大亚湾大辣甲水域溶解无机碳(DIC)的垂向分布和季节动态特征进行了研究,分析了大亚湾溶解无机碳与各环境要素(pH、水温、溶解氧和叶绿素a等)的相关性。结果表明:在春、秋和冬季,大亚湾大辣甲水域DIC含量在垂直分布上差异较小,但夏季(2008年7月)变化较为显著,DIC含量的变化范围为16.79～26.52mg·L^-1;DIC高值基本集中在中、底层水域(8～16m),尤以底层水域(13～16m)为甚;DIC含量基本呈现出春、夏季较高,秋、冬季较低的分布趋势;DIC含量与pH值和水温含量显示出了负相关关系,而与盐度呈正相关关系。     

Seasonal Abundance of Acanthamoeba rhysodes (Singh, 1952) (Protozoa: Gymnamoebia) in a Mangrove Litter-Soil Ecosystem of Gangetic-Estuary,India1,2

Acanthamoeba rhysodes has been found to be a predominant intertidal benthic gymnamoeba in the mangrove ecosystem of Sundarbans of lower deltaic Bengal, facing the Bay. The sampling zones under study were the highest high tide regions, with characteristic mangrove litter-soil, inundated twice per month during the highest ebb of spring tide. Population abundance of this species, both in its trophic and cystic forms in the three distinct seasonal periods of pre-monsoon (March to June), monsoon (July to October), and post-monsoon (November to February) has been surveyed for over two years. These seasonal periods affect the physico-chemical parameters of the habitat substrata, including temperature, pH, and salinity. It has been found that the overall number of organisms per gram of soil attains peak value during the monsoon period. This value comes down in post-monsoon samples and is the least in pre-monsoon ones.     

Fire season effects on the recruitment of non‐sprouting serotinous Proteaceae in the eastern (bimodal rainfall) fynbos biome,South Africa

Abstract Research in Mediterranean‐climate shrublands in both South Africa and Australia shows that recruitment of proteoid shrubs (non‐sprouting, serotinous Proteaceae) is best after warm‐season (summer and autumn) fires and worst after cool‐season (winter and spring) ones. This pattern has been attributed to post‐dispersal seed attrition as well as size of pre‐dispersal seed reserves. Here we investigate patterns of post‐fire recruitment for four proteoid species in the eastern part of South Africa's fynbos biome, which has a bimodal (spring and autumn) rainfall regime. Despite the lack of significant differences in recruitment between cool‐ and warm‐season burns, we find some evidence for favourable recruitment periods following fires in spring and autumn, immediately before, and coinciding with, the bimodal rainfall peaks. This suggests that enhanced recruitment is associated with conditions of high soil moisture immediately after the fire, and that rapid germination may minimize post‐dispersal seed attrition. In two of the species, we also find a shift from peak flowering in winter and spring in the Mediterranean‐climate part of the fynbos biome, to summer and autumn flowering in the eastern part. Because these two species are only weakly serotinous, warm‐season flowering would result in maximal seed banks in spring, which could explain the spring recruitment peak, but not the autumn one. We conclude that eastern recruitment patterns differ significantly from those observed in the western and central parts of the biome, and that fire management protocols for the east, which are currently based on data and experience from the winter‐rainfall fynbos biome, need to be adjusted accordingly. Fire managers in the eastern fynbos biome should be less constrained by requirements to burn within a narrow seasonal range, and should therefore be in a better position to apply the required management burns.     

Seasonal differences in energy expenditure,flight characteristics and spatial utilization of Dalmatian Pelicans Pelecanus crispus in Greece

Animals typically adjust their behaviour to their changing environment throughout the annual cycle, modulating key processes such as the timing of breeding and the onset of migration. Such behavioural changes are commonly manifested in the movements and the energetic balance of individuals in relation to their species‐specific physiological characteristics, habitat attributes and the environmental properties of their distribution ranges. We used GPS and acceleration data collected using transmitters on free‐ranging birds to quantify annual movement patterns and estimate energy expenditure of the Dalmatian Pelican Pelecanus crispus, a large, soaring avian species which performs short‐distance migration and spends its entire annual cycle in mid‐latitudes. To assess the representativeness of our results, the transmitter effect was also tested. We found that daily trends in the overall dynamic body acceleration (ODBA; a proxy for energy expenditure) differed among seasons, with the highest values occurring during spring and the lowest during winter. Long inter‐lake flights were very rare in winter, and the number of flights and ODBA during spring was higher than during summer, suggesting greater motivation to move in spring. Although transmitters may have affected the birds, as none of the tagged birds bred, we found seasonal differences in behaviour and activity level. The observed patterns in differences in activity levels, long‐distance flights and flight characteristics between seasons suggest an annual rhythm of energy expenditure. These findings allow a better understanding of bird phenology, specifically regarding adaptations to wintering in a cold climate by reducing movement‐driven energy expenditure. Finally, the identification of periods with high and low energy expenditure may guide future conservation efforts by adjusting conservation plans in accordance with changing needs during the annual cycle.     

舟山海域大中型浮游动物群落时空变化及受控要素

为更好地保护舟山海域的渔业资源和生态环境,了解舟山海域浮游动物组成的时空变化,于2014年到2017年对舟山海域33个站位开展4个季节的生态综合调查,结果表明:4个航次共鉴定出浮游动物成体88种和浮游幼体19类,优势种共12种,浮游动物的优势种更替和群落特征季节变化明显,春夏、夏秋、秋冬、冬春相邻季节优势种更替率分别为75%、80%、100%和60%;平均生物量为夏季(176.34 mg/m³)>春季(120.20 mg/m³)和秋季(86.28 mg/m³)>冬季(7.21 mg/m³);平均丰度为夏季(143.97个/m³)>春季(86.30个/m³)>秋季(21.38个/m³)和冬季(26.86个/m³);平均多样性指数:夏季(3.03)>秋季(2.82)>春季(2.05)>冬季(1.71)。舟山海域浮游动物群落具有明显的季节和区域差异,温度、盐度、Chl a和营养盐是影响舟山浮游动物群落时空变化的主要环境因素,其中春季浮游动物群落空间分布主要受盐度的影响,夏季主要受温度、盐度和Chl a的影响,秋季主要受Chl a的影响,冬季主要受悬浮物和溶解氧的影响,而营养盐对每个季节的浮游动物群落分布都有一定的影响。     

Seasonal variation in daily patterns of social contacts in the European badger Meles meles

Social interactions among hosts influence the persistence and spread of infectious pathogens. Daily and seasonal variation in the frequency and type of social interactions will play an important role in disease epidemiology and, alongside other factors, may have an influence on wider disease dynamics by causing seasonal forcing of infection, especially if the seasonal variation experienced by a population is considerable. We explored temporal variation in within‐group contacts in a high‐density population of European badgers Meles meles naturally infected with Mycobacterium bovis (the causative agent of bovine tuberculosis). Summer contacts were more likely and of longer duration during the daytime, while the frequency and duration of winter contacts did not differ between day and night. In spring and autumn, within‐group contacts peaked at dawn and dusk, corresponding with when they were of shortest duration with reduced potential for aerosol transmission of pathogens. Summer and winter could be critical for transmission of M. bovis in badgers, due to the high frequency and duration of contacts during resting periods, and we discuss the links between this result and empirical disease data. This study reveals clear seasonality in daily patterns of contact frequency and duration in species living in stable social groups, suggesting that changes in social contacts could drive seasonal forcing of infection in wildlife populations even when the number of individuals interacting remains similar.