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1.
The temporal dynamics of two seagrass species, Zostera marina and Z. japonica, were monitored monthly in Dadae Bay, Geoje Island, on the southern coast of Korea. Plant morphological characteristics, shoot density, biomass, leaf production, reproductive effort, and environmental characteristics were monitored from July 2001 to July 2002. Zostera japonica occurred in the intertidal zone and Z. marina occurred in the subtidal zone from 0.5 to 2.5 m below the mean low water level. Shoots and rhizomes were significantly larger in Z. marina than in Z. japonica, whereas the shoot density was greater in Z. japonica than in Z. marina. Despite differences in morphology and shoot density, biomass did not differ significantly between the species. Reproduction occurred from April to June in Z. marina and from May to July in Z. japonica. The proportion of reproductive shoots was approximately three times higher in Z. marina than in Z. japonica. Seasonal variation in the biomass of Z. japonica was caused by changes in both shoot size and density, whereas that of Z. marina was mainly caused by changes in shoot length. Leaf production in Z. marina and Z. japonica showed clear seasonal variation, and leaf production in Z. marina (2.6 ± 0.2 g DW·m−2·day−1) was higher than that in Z. japonica (1.7 ± 0.2 g DW·m−2·day−1). The mean plastochrone interval was not significantly different between the two species, whereas the leaf lifetime of Z. marina was longer (69 ± 7.8 days) than that of Z. japonica (59 ± 8.3 days). Our results indicated that seasonal leaf growth patterns in Z. japonica are correlated with irradiance and temperature, whereas those in Z. marina respond most to irradiance. Seasonal changes in irradiance appeared to control the temporal variation in above‐ground biomass in both species. 相似文献
2.
The effect of blue mussel (Mytilus edulis) presence in eelgrass (Zostera marina) beds was studied from June 2004 to July 2005 in Flensborg fjord, Denmark. The field experiments were conducted at two stations, one with only Z. marina (Eelgrass station) present and one where M. edulis were present in the Z. marina beds (Mixed station). Zostera marina parameters were measured (growth of leaves, shoot density, leaf length, and nutrient content) in combination with epiphyte cover and sediment parameters (sulphate reduction rates, sediment nutrient fluxes, organic content, C, N and P content) to examine possible positive and negative effects of the mussels on eelgrass performance. The fluxes of ammonium from the sediments were stimulated at all sampling dates at the Mixed station, and possibly stimulated epiphyte growth at this station. Further 15N signals in epiphytes from the Mixed station suggested that excretion products from the mussels were important nitrogen sources at this station. Sulphate reduction rates were enhanced at the Mixed station and also sediment sulphide concentrations increased under mussel influence, which may have resulted in sulphide toxicity and decreased growth of Z. marina at this station. The study indicates that for Z. marina beds in Flensborg Fjord the effects of M. edulis in seagrass beds are primarily negative, and raises the question whether this leads to negative effects on the stability and expansion of Z. marina beds. 相似文献
3.
大叶藻海草场是重要生境但在我国严重退化,亟需研究有效的修复方法。本文以桑沟湾的大叶藻种子为研究对象,探讨了盐度急变(0~30)对种子萌发、萌发后继续发育和存活及幼苗幼叶的光合与呼吸速率的影响,为以种子繁殖修复大叶藻海草场提供参考。结果表明:盐度降低促进种子萌发,盐度15及以下效果显著,盐度0时萌发率最高;盐度0~15中萌发的种子均可发育成幼苗,发育和衰亡的比例和速率受萌发盐度背景和萌发后培养盐度的双重影响——较高萌发盐度有利于种子萌发后的发育和存活,种子萌发后于盐度5~30中均可建成幼苗并存活、但在盐度0或1中发育至不同程度后全部死亡。盐度5~30范围内,幼苗幼叶均有净产氧,光合和呼吸作用及净产氧率具随盐度升高而增强趋势。于盐度0或5中萌发、盐度5~30中进一步培育的变盐育苗策略,最高实现了24%或12%的种子于2个月内建成幼苗并继续发育,可作为种子繁殖法修复大叶藻海草场的技术参考。 相似文献
4.
威海荣成桑沟湾海域海草床分布现状及其生态特征 总被引：1，自引：0，他引：1
海草床是生物圈最高产的生态系统之一，在氮捕获、碳封存、水质净化及维持生物多样性等方面发挥关键作用。2016年8月通过对威海荣成桑沟湾海域的现场调查，发现分布总面积约为471.72 ha的海草床，种类为鳗草（Zostera marina）、红纤维虾形草（Phyllospadix iwatensis）、日本鳗草（Zostera japonica）和丛生鳗草（Zostera caespitosa），分布面积分别为395.33 ha、37.28 ha、32.74 ha和6.37 ha。鳗草分布范围较广，平均茎枝密度817.0±27.6 shoots/m2，平均生物量646.6±41.8 g DW/m2；红纤维虾形草主要分布于桑沟湾北部养殖池和南部楮岛海域，平均茎枝密度2 649.0±29.8 shoots/m2，平均生物量2 381.3±27.3 g DW/m2；日本鳗草主要分布于桑沟湾西部八亩地海域，平均茎枝密度506.0±26.2 shoots/m2，平均生物量118.3±12.5 g DW/m2；丛生鳗草主要分布于桑沟湾南部楮岛海域，其平均密度为513.0±17.9 shoots/m2，平均生物量为479.1±28.1 g DW/m2。结合历史资料，发现桑沟湾海域海草床严重退化，分析了海草床的退化原因并提出了相应的建议和对策，以期为海草资源及滨海生境修复提供参考。 相似文献
5.
Paolo Guidetti Maurizio Lorenti Maria&#x;Cristina Buia Lucia Mazzella 《Marine Ecology》2002,23(1):51-67
Abstract. The temporal dynamics of three seagrasses, Posidonia oceanica, Cymodocea nodosa and Zostera marina, was studied in different areas of the Adriatic Sea by analysing phenological parameters and biomass trends in different compartments of seagrass systems. For this purpose, samplings were conducted in 1997 once per season at each station, Otranto (southern Adriatic Sea) and Grado (northern Adriatic Sea). Structural parameters and biomass of plant compartments differed among seagrasses both in absolute values and in seasonal variability. P. oceanica was the largest plant, showing the highest number of leaves per shoot, highest leaf surface, Leaf Area Index and shoot weight. Z. marina was intermediate in size and had the longest leaves, whereas C. nodosa was the smallest seagrass. P. oceanica accounted for the highest total biomass (mean ± SE: 1895.9 ± 180.2 g DW · m–2; CV = coefficient of variation: 19.0 %), considerably more than C. nodosa (mean ± SE: 410.4 ± 88.4 g DW·m–2; CV: 43.1 %) and Z. marina (mean ± SE: 312.1 ± 75.1 g DW · m–2; CV: 48.1 %), although the two latter species displayed a higher seasonal variability. Similarly, other features, such as shoot density, leaf surface, LAI, shoot weight and relative contributions of above‐ and below‐ground compartments, were less variable across seasons in P. oceanica than in the two other seagrasses, while leaf length showed the highest seasonal fluctuation in P. oceanica. As for biomass partitioning, C. nodosa showed a higher proportion of the below‐ground relative to above‐ground biomass (up to 90 %), with a distinct seasonality, whereas in P. oceanica the proportion of below‐ground biomass (around 80 %) was fairly constant during the year. We infer that in P. oceanica the seasonal forcing is probably buffered by the availability of internal resources stored permanently during the year in the below‐ground. In C. nodosa and Z. marina, instead, growth processes seem to be amplified by a greater influence of environmental factors. 相似文献
6.
黄海镆铘岛海域海草床数量分布及其生态特征 总被引：1，自引：0，他引：1
海草床是近海三大典型海洋生态系统之一,具有巨大的碳储备功能,并为众多海洋生物提供重要的栖息场所及食物来源,在维持近岸海洋生态系统平衡中发挥着重要的作用。2016年8月通过对黄海镆铘岛海域的现场调查,发现分布面积为272.84 ha的海草床主要种类为鳗草(Zostera marina)和红纤维虾形草(Phyllospadix iwatensis)。鳗草的分布面积约为177.23 ha,占总面积的65%,主要分布在镆铘岛沿岸的海参养殖池中,红纤维虾形草的分布面积约为95.61 ha,占总面积的35%,主要分布在沿岸的礁石上,呈明显的带状分布。鳗草的平均株高为(86.8±5.8)cm,平均植株密度和生物量分别为(364.0±14.2)株/m~2和(528.7±20.5)gDW/m~2;红纤维虾形草的平均株高为(112.8±3.8)cm,平均植株密度和生物量分别为(3087.0±35.4)株/m~2和(2320.0±26.6)gDW/m~2。红纤维虾形草的分布水深为(1.80±0.04)m,海草床的水体溶解氧含量较高,达到(10.4±0.1)mg/L,分布有鳗草的海参池塘的底质粒径为(4.6±0.1)mm。结合历史资料,发现该海域海草床退化现象十分严重,这除了受自然环境变化的影响外,与过度的人类活动干扰有关。并提出了海草床修复与保护的建议和对策,可为进一步研究与保护该区域海草床生态系统提供基础。 相似文献
7.
近些年来随着生境的破坏其分布面积急遽下降,较大面积连续分布的海草床已经非常少见。本研究首次将声呐探测技术应用到海草床时空分布特征的相关研究中,在河北唐山乐亭-曹妃甸沿海发现目前中国面积最大的鳗草(Zostera marina)海草床,海草床面积高达29.17 km~2,绘制了鳗草分布图和水深分布图,并对鳗草生物量和茎枝高度等基本生物学指标进行了调查。该发现极大丰富了中国海草数据库,并为鳗草的深入研究及保护提供了得天独厚的实验基地,也为周边海洋牧场的构建打下良好的基础。 相似文献
8.
We report the first record of vertical rhizome growth in the temperate seagrass Zostera marina. In a population of Z. marina occurring on subtidal sand in the Novigrad Sea (Croatia), an area subject to episodic high sediment transport, collected plants of Z. marina showed vertical rhizomes with shorter and narrower inter‐nodes (mean length = 3.4 ± 1.5 SD mm, mean width = 1.9 ± 0.3 SD mm) than those recorded for horizontal rhizomes (mean length = 9.0 ± 3.5 SD mm, mean width = 2.8 ± 0.4 SD mm). Out of a sample of 1130 rhizome fragments, 288 (25.5%) were vertical. Repeated moderate burial events may have stimulated the production of vertical rhizomes, and the ability of Z. marina to produce vertical rhizomes may enable it to withstand moderate burial in this highly dynamic environment. 相似文献
9.
A comparison of growth patterns between non‐indigenous Halophila nipponica and the native sympatric Zostera marina on the southern coast of the Korean peninsula 
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下载免费PDF全文 The growth dynamics of two co‐occurring seagrass species, Zostera marina and Halophila nipponica, were examined on the southern coast of the Korean peninsula. Zostera marina is a native dominant seagrass species in Korean coastal waters, whereas H. nipponica is a non‐native tropical and subtropical species that has extended its distributional range to the temperate coastal areas of Korea. To examine the differences in the growth dynamics of H. nipponica and Z. marina, their morphology, density, productivity and biomass, as well as local environmental conditions, were monitored monthly from January 2008 to July 2009. Underwater irradiance at the study site was the highest in April 2009 and the lowest in January 2008. Water temperature ranged from 10.4°C in January 2009 to 24.8°C in September 2008. Significant differences in growth dynamics were observed between the species, due to the effect of water temperature at the study site. Density and areal productivity were the highest in April 2008 and June 2008, respectively, for Z. marina but the highest in July 2008 for H. nipponica. Leaf size, shoot height and shoot weight were the highest in July 2008 for Z. marina but the highest in August 2008 or September 2008 for H. nipponica. The productivity of both species was strongly correlated with water temperature at the study site. However, the productivity of these species was not strongly correlated with underwater irradiance or the nutrient availability of either the water column or sediment pore water. Zostera marina exhibited the ecological characteristics of a temperate seagrass, whereas H. nipponica retained the features of a subtropical/tropical seagrass, even after adapting to the temperate coastal waters of Korea. 相似文献
10.
Plus Martin Dalloyau Sébastien Trut Gilles Auby Isabelle Xavier de Montaudouin Éric Emery Noël Claire Viala Christophe 《Estuarine, Coastal and Shelf Science》2010
The spatial variability of seagrass meadows in Arcachon Bay, was studied between 1988 and 2008 using a combination of mapping techniques based on aerial photographs for intertidal dwarf-grass (Zostera noltii) beds and acoustic sonar for permanently submerged eelgrass (Zostera marina) populations. The results show a severe decline over the period for both species, as well as an acceleration of the decline since 2005 for Z. noltii. The total surface regression over the studied period is estimated to be 22.8 km2 for Z. noltii and 2.7 km2 for Z. marina, which represent declines of 33 and 74% respectively. 相似文献
11.
鳗草(ZosteramarinaL.)广布于北半球温带浅海海域,其形成的鳗草床具有重要的生态价值。近些年来,我国黄渤海海域鳗草退化严重,较大面积、连续分布的海草床已经非常少见。在渤海兴城-觉华岛海域发现较大面积的海草床,可以作为渤海沿海海草床的典型代表。基于此,2018年5月、9月、11月和2019年3月对该海草床进行了初步调查,探究了渤海兴城-觉华岛海草床鳗草种群补充等生态特征,分析了海草床生境的主要威胁,并提出了对海草床进行有效保护和科学管理的相关建议。结果表明:渤海兴城-觉华岛海草床总面积为791.61ha,海草种类为鳗草和日本鳗草(Z.japonica),以鳗草为优势种,日本鳗草极少且呈斑块状分布;鳗草生物量在2018年5月达到最大值(1241.22—1632.64g/m2);鳗草叶片碳、氮、磷元素含量分别为35.35%—36.57%、1.89%—3.35%、0.14%—0.48%;鳗草海草床以无性繁殖为主要补充方式,有性繁殖补充比例平均仅为1.92%,明显低于国内其他鳗草草床,具有鲜明的独特性;该海草床主要受围填海、捕蛤、围网捕鱼等人类活动的严重影响,并致使海草床边缘区域呈现斑块化趋势。建议对这片珍贵的海草床加以保护和修复。 相似文献
12.
The genetic diversity and differentiation of four Zostera marina populations along the southern coast of Korea were estimated using random amplified polymorphic DNA (RAPD) markers to determine the effects of natural and anthropogenic stresses and reproductive strategy on within‐population genetic diversity. The mean number of alleles and gene diversities, indicating population genetic diversity, was highest in the Z. marina population that was exposed to repeated environmental disturbances, and lowest in the most undisturbed population. The higher genetic diversity in the disturbed population was associated with a higher contribution of sexual reproduction to population persistence. This suggests that both the level of disturbances and the reproductive strategy for population persistence contributed significantly to population genetic diversity at the study sites. According to the analysis of molecular variance (AMOVA), 76% genetic variation was attributable to differences among individuals within populations. The observed genetic differentiation (FST = 0.241) among Z. marina populations at the study sites appeared to result from reduced meadow size, increased genetic drift, and a high incidence of asexual reproduction. Increased population genetic diversity can enhance resistance and resilience to environmental disturbances; thus, this investigation of seagrass population genetics provides valuable new insights for the conservation, management, and restoration of seagrass habitats. 相似文献
13.
Masumi Yamamuro Jun-Ichi Hiratsuka Yu Ishitobi Shinya Hosokawa Yoshiyuki Nakamura 《Journal of Oceanography》2006,62(4):551-558
Zostera marina L. was intensively harvested until the early 1950s in Lake Nakaumi, a eutrophic estuarine lagoon. We have estimated the amount
of nitrogen (N) and phosphorus (P) removed from the lagoon through Z. marina harvesting. Lake Nakaumi lies in Tottori and Shimane prefectures, and the annual harvest of Z. marina in the late 1940s in Tottori was recorded as at least 56,250 t wet weight. The nutrient content of 56,250 t of Z. marina was calculated to be 61.9 t of N and 12.9 t of P, which is equivalent to 5.3% and 11%, respectively, of present annual nutrient
loads to the lake. The nutrients formerly used by Z. marina were likely used by phytoplankton after the Z. marina started to decline in the mid-1950s at Lake Nakaumi. This shift in the chief primary producer, from benthic macrophytes to
phytoplankton, caused a subsequent shift in secondary producers. Benthic fish and crustacean populations decreased and the
non-commercial filter-feeding bivalve, Musculus senhausia, increased in Lake Nakaumi after the decline of seagrass beds. This affected the local economy, inducing not only eutrophication
but also the collapse of local fisheries. On the other hand, at adjacent Lake Shinji, loss of submerged aquatic vegetation
induced an increase of the commercial filter-feeding bivalve, Corbicula japonica, which doubled the fishery yield in the lake. 相似文献
14.
The objectives of this study were to determine the distribution and abundance of Zostera marina (eelgrass) in relation to the distribution of the mat forming bacteria Beggiatoa spp., and the levels of sulfide and organic material (wood waste) in the sediment. Underwater videography and intertidal surveys were used to map the distribution and abundance of Z. marina beds and Beggiatoa in the nearshore area of Commencement Bay, WA (USA), a location that has a long history of sawmill activity. Zostera marina occurred from the intertidal to ?6 m mean lower low water (MLLW) on sandy substrates in areas with low levels of sulfide (<50 μm ) and organic material (<5 % total volatile solids). Areas with high sulfide levels (>200 μm ) occurred where there were significant amounts of organic material in the sediments, which was found to be wood waste that had been discarded from sawmills. Zostera marina was absent from the intertidal and occurred at lower densities in areas with high sulfide levels. In contrast, mats of Beggiatoa were only found in areas where the sulfide levels were >1000 μm and there were significant deposits of wood. Thus, the negative correlation between the distribution and abundance of Z. marina and Beggiatoa suggests that the presence of Beggiatoa mats could be used as a biological indicator of inhibiting levels of hydrogen sulfide in the marine environment. 相似文献
15.
Vast declines in Zostera marina seagrass beds demand effective methods of rehabilitation. In this study, we developed a practical method by reducing salinity to induce seed germination followed with recovering salinity to facilitate seedling production of Z. marina. The results showed that Z. marina seeds collected from natural seawater(salinity 30) were induced to germinate at reduced salinities. Percent germination(GR) was higher and mean-time-to-germinate(MTG) was shorter at lower salinities. The highest GR and shortest MTG occurred at salinity 0(deionized freshwater). After germination in freshwater, seeds could develop into seedlings at salinities5–30 and continue the growth. Viability or development of germinated seeds was not significantly different during the 40 d of post-germination incubation at salinities 5–15 after 1–20 d of germination in freshwater. However,during the process of translating germinated seeds from salinity 0 and 5 to salinity 30, reducing the gradients of post-germination acclimation facilitated more seeds forming seedlings in less time. On average, after 60 d of static incubation, including 20 d in freshwater for germination followed with immediate shift to salinity 5 and increasing to salinity 30 at increment of 5 every two days until cultivation at constant salinity 30, 33% of Z. marina seeds produced healthy seedlings. The results indicate that the salinity-manipulation based method of artificial germination and seedling production is practical and effective in supporting rehabilitation of Z. marina bed. 相似文献
16.
山东荣成天鹅湖海草场大型底栖贝类时空分布研究 总被引：1，自引：1，他引：0
为了了解天鹅湖不同微生境条件下底栖贝类的群落结构及时空分布特征,于2013年12月至2014年11月,对天鹅湖矮大叶藻区、空白区、大叶藻区边缘及其内部的底栖贝类和环境特征进行了调查。共发现15种大型底栖贝类,隶属14科15属;贝类种类组成、分布密度、生物量以及物种多样性指数在4种生境中差异显著,但均无明显的季节变化。空白区域中贝类总密度和单位面积生物量最高,大叶藻区内部最低,但矮大叶藻区和大叶藻区内部多样性指数较高。大叶藻区内部的贝类以腹足类锈凹螺、日本月华螺、刺绣翼螺等刮食者为主,而双壳贝类则更倾向于选择无海草覆盖的空白区或者海草较为稀疏的草场边缘。综合分析表明,天鹅湖底栖贝类的分布和多样性受底质特征和海草覆盖影响最为显著,同时与水深密切相关。 相似文献
17.
18.
The neritid Smaragdia viridis represents the only known native marine mollusc that feeds on seagrass tissues in the European coasts, displaying a strong association with the seagrasses Cymodocea nodosa and Zostera marina in southern Spain. Seasonal dynamics, shell and radular morphology, growth and feeding of this gastropod have been studied in relation to each seagrass species for contrasting trends resulting from a different type of substrate and food source. In both seagrass species, stable populations of this gastropod occur at similar densities and displaying similar growth rates. Nevertheless shells of individuals from C. nodosa are narrower than those from Z. marina and some differences, possibly a consequence of increased wearing on C. nodosa, were noted amongst the radulae. In C. nodosa, a pre-ingestive selection for young epidermal tissues occurs as it was previously observed in Z. marina. The ingestion rate is higher in C. nodosa than in Z. marina but the absorption of ingested tissues is lower in the former. If both seagrasses are present, most individuals ingested preferentially Z. marina rather than C. nodosa, probably due to the lower digestibility of the epidermal tissues in the latter. Seagrass beds, especially those of Z. marina, are suffering a strong regression in southern Spain and the presence of stable populations of this neritid may be restricted to other declining seagrass species in the area. 相似文献
19.
The plant reproductive effort, the seed germination rate and the seedling survival and development of Zostera marina (eelgrass) were assessed in four populations (Fuzeta, Culatra, Barrinha and Armona) at the species’ southern distribution limit in the Eastern Atlantic, the Ria Formosa lagoon. Germinated seeds were individually placed in Petri dishes with natural sandy sediments and kept in a culture chamber at the same temperature and salinity conditions as the natural environment. In addition, seeds from three different depths of Fuzeta population were cultivated in outdoor mesocosms. The populations of Fuzeta and Barrinha showed higher seed production and the seeds produced were heavier than the other populations. The germination of the seeds both in the laboratory and in the outdoor tanks began c. 8–12 weeks after the collection of the flowering shoots at a water temperature of 22 °C. The spontaneous germination in the laboratory (2.4–5.3%) and in the mesocosm experiment (5.6–8.9%) was low and from all the germinated seeds (n = 20) only three reached the seedling stage. The spontaneously germinated seeds from Fuzeta survived for a longer period than those from Barrinha, but only the germinated seeds of Barrinha reached the seedling stage (one‐leaf seedling stage). In outdoor tanks, higher seed germination and earlier seedling emergence (2 weeks after seeding) and survival (for 208 days) occurred for the seeds obtained from the shallow meadow. The reproductive effort of Z. marina populations of Ria Formosa showed that flowering shoots and seed traits are site‐specific. The low reproductive success indicated by the low germination and seedling survival suggests a bottleneck in the species’ reproductive cycle that may account for the scarce presence of the species in Ria Formosa lagoon. The high water temperatures of Ria Formosa in winter may partly explain this bottleneck. Increased temperatures due to climate change may reduce even further the sexual reproduction of Z. marina in its southern distributional limit in the Eastern Atlantic. 相似文献
20.
Guillaume Bernard Charles F. Boudouresque Philippe Picon 《Estuarine, Coastal and Shelf Science》2007,73(3-4):617-629
The Berre lagoon (Provence, France), one of the largest Mediterranean brackish lagoons (155 km2), was occupied, at the turn of the 20th century, by extensive Zostera meadows (Zostera marina and probably Zostera noltii; perhaps over 6000 ha). Subsequently, the lagoon was disturbed by urban and industrial pollution and, from 1966, by the diversion of the Durance River. This resulted in a 10–49-fold and 8–31-fold increase of the freshwater and silt inputs, respectively. By means of digital analysis of aerial photographs for the years 1944, 1992, 1998 and 2004, coupled with ground truth for the last three dates, we mapped the Zostera meadows. The replacement of Z. marina by Z. noltii, the latter species being already dominant in the 1970s, was completed in 1990. In parallel to this substitution, the Zostera beds underwent a dramatic decline. Their depth limit, which was (6–9) m in the early 20th century, withdrew to 3.5, 3, 1 and less than 1 m by 1944, the 1970s, 1992 and 1998, respectively. Since 1998, Zostera must be considered as functionally extinct. The total surface area of Zostera meadows was of the order of 1.5 ha in 2004. In an attempt to alleviate disturbance, the input of freshwater and silt from the Durance River was significantly reduced from the early 1980s and 1990s respectively. Similarly, from the 1970s to the 1990s, urban and domestic pollution was drastically reduced. Despite these steps, Zostera meadows continued to shrink to near extinction. The lagoon has shifted from a system dominated by seagrass beds to a system with bare silt bottoms, which now occupy most of the lagoon. The reasons could be, in addition to continuing nutrient inputs, the resuspension of silt, no longer trapped under the seagrass canopy, during wind episodes, which are frequent in the area, and/or the release of nutrients from the bare silt habitat, which would constitute an indication of a possible hysteresis of the system. However, since 2000, the establishment of the mussel Mytilus galloprovincialis, a drop in turbidity and a slight, inconspicuous progression of Z. noltii could be the harbinger of a reverse shift of the system. 相似文献