(B) Total number of shoots (primary and lateral shoots). here. The pots were then transferred to the outdoor tanks with one replicate pot in each of the 5 tanks, yielding a total of 70 pots with unsorted seeds (7 depths, 2 sampling times) and 30 pots (3 depths) with small and large seeds, respectively. The best conditions for storing, Planting the seeds at sea is one of the most critical steps. While the biomass of seedlings was unaffected by seed burial depth at the first sampling in June, 4–5 weeks after peak seedling emergence, the aboveground biomass was significantly higher for seedlings originating from deeply buried seeds (8 cm: 275.5 mg DW seedling-1) compared to shallow seeds (1 cm: 87.4 mg DW seedling-1) 4 months later (Fig 2, Table 5). The optimum depth for successful recruitment was within the top 2 cm, which is in accordance with previous studies [20,21]. Eelgrass (Zostera marina) flowering development and seed production were assessed along a depth gradient at three sites during 2012 and 2013 to 1) describe the flowering seasonality in the Swedish west coast, and 2) evaluate methods using seeds for large-scale restoration, including harvesting, storage and separation of viable seeds using a vertical flume. In this study, seed germination leading to successful seedling emergence occurred at sediment depths down to 8 cm, but increasing seed burial depth severely reduced the number of emerging seedlings and delayed the time of emergence from sediment depths below 3 cm. For Z. marina, the relatively fast elongation of the hypocotyl proceeds mainly through cell expansion and accumulation of water rather than by cell division [29], which may partly explain the similar length growth and time of emergence for large and small seeds in this study. Likewise, burial depth affected the total seedling emergence of sorted seeds, but there was no significant difference between large and small seeds (Fig 1B, Table 3). Zostera marina seeds Seeds of Zostera marina (eelgrass) can be used for restoration if they are available. Moreover, large seeds produced larger seedlings than small seeds. More details of this methodology and data in (Infantes et al 2018), After harvesting, flowering shoots can be stored in tanks on land until seeds naturally drop from the spathes. We prepared two depth-series of unsorted seeds to be able to an analyse the fate of seeds remaining in the sediment and the biomass of seedlings, just after the period of maximum seedling emergence (sampled after 2 months) and at the end of the growing season (sampled after 6 months). 2006d). Flowering shoots were stored for 2 months in tanks until seeds were collected. Conceptualization, Zostera marina seeds were classified by seed color (oyster white, cyan, or black), representing the various degrees of seed maturity (immature, medium, and advanced maturity, respectively). On the other hand, harvesting after the seeds have matured might not be efficient since many seeds could be already released in the field. Zostera marina seeds were harvested by mechanical harvester in early June 2011 from a bed on the Atlantic side of the Delmarva Peninsula. Seedling emergence tended to be greatest within the top 2 cm, which corresponds to the optimal range of sediments depths to maximize seedling emergence previously identified for Z. marina [20,21]. Along the mid‐Atlantic coast of North America Z. marina seeds are shed from late spring through early summer, but seeds typically do not begin to germinate until the late fall. 2011. The survival functions (i.e., the function that associates a given time with the probability of emergence after that time) for the distribution of the emergence times were estimated using a non-parametric estimate specially designed for interval censored times as described in [37] and [38]. This suggests that smaller seeds were more receptive to environmental stimuli than larger seed, but had a reduced ability to reach the surface from greater burial depths. We therefore also hypothesized that the biomass of newly emerged seedlings decrease with increased seed burial depth and reduced seed mass. However, it is not clear whether this was caused by accumulation of reduced elements such as ammonium or sulphide or soluble organic toxins derived from anaerobic microbial activity [46]. This study was supported by the “NOVAGRASS" project (12–132701) funded by the Danish Council for Strategic Research. https://doi.org/10.1371/journal.pone.0215157.t004. Funding acquisition, Intensive efforts have been made to restore seagrass communities along the coast to restore the function of the coastal ecosystem. https://doi.org/10.1371/journal.pone.0215157.t005. Conceptualization, This suggests that there is an optimal sediment depth for successful sexual recruitment, and that the vertical distribution of the seed bank is critical for successful seedling establishment. Supervision, In general, large seeds show higher percentage seedling emergence and are more likely to emerge from greater depths than small seeds [42,49], but the opposite has also been observed [50]. Zostera marina seeds were harvested by mechanical harvester in early June 2011 from a bed on the Atlantic side of the Delmarva Peninsula. Similar results were also reported by [15], who showed that large Z. marina seeds had greater survival than smaller seeds during long-term storage in water cultures. The biomass of seedlings derived from large and small seeds was not significantly affected by seed burial depth at time of sampling (5–6 weeks after peak emergence), but large seeds gave rise to significantly larger seedlings that on average weighed 1.5 times more than seedlings formed by small seeds (Fig 3, Table 5). Pre-emergence seedling mortality has for terrestrial plant species been linked to insufficient seed energy reserves to support seedling elongation until reaching the soil surface and transition to autotrophy [42]. The causes of eelgrass losses are still unclear making it difficult to develop effective management measures and a legal framework to support it. Generalized linear mixed model testing the effect of sediment depth on seedling emergence from unsorted seeds, and generalized linear model for effect of depth and seed size on emergence from large and small seed size classes (sorted seeds). The vertical flume is a low cost construction that produce a vertical flow from the bottom of a tube towards the top. The fraction of unsorted seeds that germinated but did not successfully emerge, as indicated from the number of empty, split seed coats, was unaffected by seed burial depth and time after planting (2 and 6 months), and constituted a small fraction of 8.0 ± 1.3% of total planted seeds across all seed burial depths (Fig 1C and 1E, Table 4). Restoration Using Zostera marina (eelgrass) Seeds Scott R. Marion1 and Robert J. Orth1,2 Abstract The use of Zostera marina (eelgrass) seeds for seagrass restoration is increasingly recognized as an alternative to transplanting shoots as losses of seagrass habitat gener-ate interest in large-scale restoration. Recent studies suggest that the primary mechanism behind the overall decline is an increased abundance of epiphytic algal mats caused by eutrophication and overfishing, which results in reduced light conditions and increased anoxic events. We conducted seed dispersal experiments in the field and laboratory to better describe seed dispersal characteristics in one species, Zostera marina L. (eelgrass), the dominant seagrass species in the temperate zone of the United States, Japan, and Europe. The goal of this work was to determine the role that benthic infauna play in the burial of Z. marina seeds by addressing the following questions: 1. Hence, viable eelgrass seeds have been found down to sediment depths of 8 cm in an annual seagrass meadow [24] and as deep as 14 cm in a dieback area of a former perennial meadow [25]. In contrast, the number of unemerged seeds that remained viable in the sediment throughout the study period was much higher among large Z. marina seeds suggesting longer persistence than for small seeds. The latter are probably very important in the reestablishment of eelgrass beds in denuded areas. To count the total number of seeds collected, the number of seeds in 1gr could be counted and then multiplied by the total weight of the seeds. We deployed seed predation units (SPU) within patches ranging in size from 0.28 to 28.48 m 2, and on unvegetated, sandy bottom. Other studies have shown that seedling biomass increases with seed mass, and that this may result in higher survival and competitive ability during early seedling establishment [49–51]. Leaves can grow to 4 feet in length. However, the increased inhibition of germination with depth suggests that interactive effects of sediment properties related to depth were involved. The arrow indicates when fertilizer was added to two treatments (sand + fertilizer; estuarine sediments + fertilizer). Thanks for you reply! Water temperature increased from 16 °C to 19 °C during the first three weeks of the experiment, when most of seedlings emerged. Software, https://doi.org/10.1371/journal.pone.0215157.g001. Since shoots tend to float, a mess cover was used to keep all the shoot submerged. Formal analysis, As most clonal plants, Z. marina can use both asexual and sexual reproduction to recover from disturbances. The lack of a persistent seed bank may reduce the resilience of Z. marina at the limits of the species distribution to repeated stress events. The importance of individual model terms and interactions was assessed via a likelihood ratio test. No, Is the Subject Area "Mathematical models" applicable to this article? To obtain enough ripe seeds, flowering Zostera marina – shoots from different sites in the Baltic Sea and one Mediterranean site were harvested after seeds had been formed by the plants (Tab. Is the Subject Area "Seeds" applicable to this article? Like most seagrass species, Z. marina is regularly found at highly disturbed sites, where sediment dynamics caused by hydrodynamic forces or activity of burrowing animals may influence adult plant performance and re-establishment from seeds [12,28,52,53]. The causes of delayed germination of large seeds are unknown, but may be related to seed characteristics such as thicker seed coats that excludes environmental cues and protects the embryo against adverse pore water conditions. Contrary to our hypotheses, the initial seedling biomass was not negatively affected by germination depth, although the emergence from deeply buried seeds (4–6 cm) was delayed by 5–15 days compared shallower seeds, and by the end of the six month experimental period, seedlings originating from deeply buried seeds even tended to have larger biomass. With the improvement of conditions, there is a growing interest to restore lost habitats, but methods are lacking for restoration of eelgrass beds at high latitudes where long winters create special challenges. The viable seeds which are more dense tend to sink faster to the bottom while the non-viable seeds which are less dense are transported out of the tube. In addition, larger starch reserves may enable seeds to persist longer when unfavourable conditions are encountered, as suggested by [19]. Click through the PLOS taxonomy to find articles in your field. Hence, earlier loss of dormancy in small seeds of terrestrial plants species has been attributed to larger surface to volume ratio as well as thinner seed coats, allowing for more rapid uptake of water [50]. Letters indicate significant difference (P<0.05) between seed sediment depths of unsorted seeds and between seed size and sediment depth of the small and large seed size classes. Abstract: Eelgrass (Zostera marina) seeds are being used in a variety of both small-and large-scale restoration activities and have been successfully used to initiate recovery of eelgrass in the Virginia seaside coastal lagoons, which lost eelgrass PLOS ONE promises fair, rigorous peer review, latifolia Morong: ZOMAS: Zostera marina L. var. Here some seeds may be lost due to predation, attack by pathogens or dispersal to unfavourable sites, while those that become entrapped in the sediment provide a seed bank, where they may remain dormant and viable for more than 12 months [12,15]. burial. Regardless of seed burial depth, large seeds gave rise to seedlings that in the early stages of development produced more biomass than seedlings originating from smaller seeds. Study on Zostera marina L. Seed Germination Ecological Characteristics in Variable Environmental. From March 2015 and until experimental start in late April, the seeds were stored in the laboratory at 5 °C to reduce germination. In this study, the presence of unsuccessfully emerged seeds was generally low and unaffected by depth, although the proportions tended to be higher at 4–8 cm depth (12–13.6%) than at 1–3 cm depth (2.7–5.3%) after 6 months in the sediment. A vertical flume flume can be used for this purpose. Water temperature was recorded every 30 min by HOBO temperature loggers (U22-001) placed in each tank at the start of the experiment. 3) Assist with field collection of Z. marina flowering shoots. The moisture content and WW of seeds at different degrees of maturity both exhibited a significant difference (F = 1,055, df = 17, p < 0.001; F = 1,253, df = 17, p < 0.001, respectively). Predation was examined initially by offering seeds or seedlings as a sole food source for a maximum period of one week. Formal analysis, The maximum potential seed production was greatest at S1 (22228.52 ± 8832.46 seeds ⋅ m –2), followed by S2 (21630.34 ± 9378.67 seeds ⋅ m –2), H2 (7459.60 ± 1779.33 seeds ⋅ m –2), and H1 (2821.05 ± 1280.57 seeds ⋅ m –2). seed bank played major role in recolonizing a lost eelgrass meadow due to … Zostera marina is a species of seagrass known by the common names common eelgrass and seawrack. Restoration projects should assess the seed maturation time on their locations. All plants were collected via snorkelling in 1-3m depth. 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