Anthesis and seed production in Zostera marina L. (eelgrass) from the chesepeak by

Silberhorn, Gene; Orth, Robert J.; Moore, Kenneth A.

doi:10.1016/0304-3770(83)90024-4

Cited by 97 publications

(64 citation statements)

References 15 publications

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“…They also produced a greater number of flowering shoots per m −2 (maximum 603 ± 157 shoots m ; Phillips et al 1983b, this study). In addition, a larger proportion of reproductive shoots (33 ± 3%) were found in the mixedannual population compared to perennial beds (<10 to 28% of total shoots; Jacobs & Pierson 1981, Silberhorn et al 1983, Thayer et al 1984, Olesen 1999. This is, however, significantly less than typical annual meadows where 100% of the shoots flower (Keddy & Patriquin 1978, Robertson & Mann 1984, Meling-López & Ibarra-Obando 1999, and more similar to average densities of reproductive shoots produced in perennial populations.…”

Section: Attributes Of a Mixed-annual Life Historymentioning

confidence: 83%

“…This was much earlier than perennial populations within the region which exhibit biennial characteristics and do not flower until their second year of growth (Silberhorn et al 1983, Phillips et al 1983b, Thayer et al 1984. They also produced a greater number of flowering shoots per m −2 (maximum 603 ± 157 shoots m ; Phillips et al 1983b, this study).…”

Section: Attributes Of a Mixed-annual Life Historymentioning

confidence: 94%

“…At NC1 and NC2 the seed bank density declined so that by the fall of 2008, following the period of maximum germination for this region (Silberhorn et al 1983, Thayer et al 1984, < 2% of that year's estimated seed production remained viable in the sediment. Similar large losses of seeds, ranging from 25 to 78% of total seed production, have been reported for both annual and perennial Zostera marina beds (Santamaría-Gallegos et al 2000, Harwell & Orth 2002b, Morita et al 2007).…”

Section: Attributes Of a Mixed-annual Life Historymentioning

confidence: 98%

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Characterization and ecological implication of eelgrass life history strategies near the species’ southern limit in the western North Atlantic

Jarvis¹,

Moore²,

Kenworthy³

2012

Mar. Ecol. Prog. Ser.

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Eelgrass Zostera marina L. populations located near the species southern limit in the western North Atlantic were assessed monthly from July 2007 through November 2008. We identified (1) dominant life history strategies and local environmental conditions in southern Z. marina populations, (2) quantified differences in reproductive phenology between populations and different local environmental conditions, and (3) compared reproductive strategies to established annual and perennial life history paradigms. Observed populations expressed both life history strategies with one Z. marina population completely losing aboveground biomass and reestablishing from seeds (annual model) while another population retained aboveground biomass throughout the year (perennial model). A third life history strategy, characterized here as a mixed-annual population, was also observed after some seedlings were found to reproduce both sexually and asexually during their first year of growth thereby not conforming to any currently established life history paradigm. Development of multiple life history strategies within this region may be in response to stressful summer water temperatures associated with the southern edge of the species' range. We suggest that neither annual nor perennial life history strategies always provide a superior mechanism for population persistence as perennial populations can be susceptible to multiple consecutive years of stress, and annual populations are unable to fully exploit available resources throughout much of the year. The mixed-annual strategy observed here represents another possible life history model which may provide the mechanism necessary for Z. marina populations to persist during times of environmental transition.KEY WORDS: Zostera marina · Life-history · Annual · Perennial · Seed bank · Biomass Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 444: [43][44][45][46][47][48][49][50][51][52][53][54][55][56] 2012 populations have also been documented to express behavior similar to the biennial life history model (Setchell, 1929). After germinating, seedling growth in biennial populations occurred via clonal expansion only and flowering stem development and fruiting were not observed until after a period of 1 to 2 yr of growth (Setchell 1929;Thayer et al. 1984). More recently an annual life history strategy has been described for Z. marina populations, where mature plants consist of reproductive (flowering) shoots only and all plants complete their life cycle (seeds germinate, flower, produce seeds) and die within 12 mo (Keddy & Patriquin, 1978, Gagnon et al. 1980, De Cock 1981, Harlin et al. 1982, Phillips et al. 1983a, Robertson & Mann 1984, Santamaría-Gallegos et al. 2000.Although they have been documented throughout the species' geographic distribution, annual forms of Zostera marina are primarily found in areas characterized by stressful environmental conditions such as ice scour (Robertson & Mann 1984), extreme temperatures (Phillips...

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Section: Attributes Of a Mixed-annual Life Historymentioning

confidence: 83%

Section: Attributes Of a Mixed-annual Life Historymentioning

confidence: 94%

Section: Attributes Of a Mixed-annual Life Historymentioning

confidence: 98%

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Characterization and ecological implication of eelgrass life history strategies near the species’ southern limit in the western North Atlantic

Jarvis¹,

Moore²,

Kenworthy³

2012

Mar. Ecol. Prog. Ser.

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“…Temperature is a main driver of phenology and lower temperatures may, for instance, lead to delayed flowering of eelgrass at increasing latitude as this plant can initiate inflorescence at very cold temperature (0.5-3 • C), but requires about 1 month and 14-15 • C for anthesis, and a further month for mature fruits to develop (Silberhorn et al, 1983). Mature fruits are developed already in April at the southern limit of this seagrass species, whereas in Nova Scotia at 44 • N this happens only in July (Silberhorn et al, 1983). The Godthåbfjord system (64 • N, Nuuk, Greenland), is the northernmost location on the Greenland coast where eelgrass has been seen to develop mature fruits, but not until late August and only in warmer inner fjord branches .…”

Section: Macrophyte-dominated Ecosystems In a Warmer Arcticmentioning

confidence: 99%

Expansion of vegetated coastal ecosystems in the future Arctic

2014

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Warming occurs particularly fast in the Arctic and exerts profound effects on arctic ecosystems. Sea ice-associated ecosystems are projected to decline but reduced arctic sea ice cover also increases the solar radiation reaching the coastal seafloors with the potential for expansion of vegetated habitats, i.e., kelp forests and seagrass meadows. These habitats support key ecosystem functions, some of which may mitigate effects of climate change. Therefore, the likely expansion of vegetated coastal habitats in the Arctic will generate new productive ecosystems, offer habitat for a number of invertebrate and vertebrate species, including provision of refugia for calcifiers from possible threats from ocean acidification, contribute to enhance CO 2 sequestration and protect the shoreline from erosion. The development of models allowing quantitative forecasts of the future of vegetated arctic ecosystems requires that key hypotheses underlying such forecasts be tested. Here we propose a set of three key testable hypotheses along with a research agenda for testing them using a broad diversity of approaches, including analyses of paleo-records, space-for-time substitutions and experimental studies. The research agenda proposed would provide a solid underpinning to guide forecasts on the spread of marine macrophytes onto the Arctic with climate change and contribute to balance our understanding of climate change impacts on the arctic ecosystem through a focus on the role of engineering species. Anticipating these changes in ecosystem structure and function is key to develop managerial strategies to maximize these ecosystem services in a future warmer Arctic.

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“…1) suggests that germination occurs in the fall regardless of latitude, suggesting that dormancy may be under environmental rather than inherent physiological control (Baskin & Baskin 1998). Other observational studies have addressed issues of timing of flowering (Jacobs & Pierson 1981) and seed production (Phillips et al 1983, Silberhorn et al 1983, and seed release ( Fig. 1) along latitudinal gradients; however, seed dormancy has not been tested along a latitudinal gradient under rigorous experimental conditions.…”

Section: Dormancymentioning

confidence: 99%

A review of issues in seagrass seed dormancy and germination:implications for conservation and restoration

Orth¹,

Harwell²,

Bailey³

et al. 2000

Mar. Ecol. Prog. Ser.

183

116

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Seagrasses have received considerable attention over the past 2 decades because of the multiple ecological roles they play in estuarine and coastal ecosystems and concerns over worldwide losses of seagrass habitat due to direct and indirect human impacts. Restoration and conservation efforts are underway in some areas of the world, but progress may be limited by the paucity of information on the role of seeds in bed dynamics. Although flowering occurs in most of the 58 seagrass species, seed germination data exist for only 19 of the 42 species that have some period of dormancy, with only 93 published references to field and/or laboratory studies. This review addresses critical issues in conservation and restoration of seagrasses involving seed dormancy (e.g. environmental vs physiological), existence and type of seed bank (transient or persistent), and factors influencing seed germination (e.g. salinity, temperature, light). Results of many earlier published studies relating seed germination to various environmental factors may need re-examination given more recent published data which show a confounding influence of oxygen level on the germination process. We highlight the importance of conducting ecologically meaningful germination studies, including germination experiments conducted in sediments. We also identify questions for future research that may figure prominently in landscape level questions regarding protected marine or estuarine reserves, habitat fragmentation, and restoration.

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Anthesis and seed production in Zostera marina L. (eelgrass) from the chesepeak by

Cited by 97 publications

References 15 publications

Characterization and ecological implication of eelgrass life history strategies near the species’ southern limit in the western North Atlantic

Characterization and ecological implication of eelgrass life history strategies near the species’ southern limit in the western North Atlantic

Expansion of vegetated coastal ecosystems in the future Arctic

A review of issues in seagrass seed dormancy and germination:implications for conservation and restoration

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