Marine
            <i>Phytophthora</i>
            species can hamper conservation and restoration of vegetated coastal ecosystems

Govers, Laura L.; Veld, Willem A. Man in ‘t; Meffert, Johan P.; Bouma, Tjeerd J.; Rijswick, Patricia C. J. van; Heusinkveld, Jannes H. T.; Orth, Robert J.; Katwijk, M.M. van; Heide, Tjisse van der

doi:10.1098/rspb.2016.0812

Cited by 41 publications

(71 citation statements)

References 66 publications

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“…nitida has been described. In addition, a sediment layer might also have additional effects such as preventing the development of marine phytophthora species [58]. …”

Section: Discussionmentioning

confidence: 99%

Seed Predation by the Shore Crab Carcinus maenas: A Positive Feedback Preventing Eelgrass Recovery?

Infantes¹,

Crouzy²,

Moksnes³

2016

PLoS ONE

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There is an increasing interest to restore the ecosystem services that eelgrass provides, after their continuous worldwide decline. Most attempts to restore eelgrass using seeds are challenged by very high seed losses and the reasons for these losses are not all clear. We assess the impact of predation on seed loss and eelgrass establishment, and explore methods to decrease seed loss during restoration in the Swedish northwest coast. In a laboratory study we identified three previously undescribed seed predators, the shore crab Carcinus maenas, the hermit crab Pagurus bernhardus and the sea urchin Strongylocentrotus droebachiensis, of which shore crabs consumed 2–7 times more seeds than the other two species. The importance of shore crabs as seed predators was supported in field cage experiments where one enclosed crab caused 73% loss of seeds over a 1-week period on average (~ 21 seeds per day). Seedling establishment was significantly higher (14%) in cages that excluded predators over an 8-month period than in uncaged plots and cages that allowed predators but prevented seed-transport (0.5%), suggesting that seed predation constitutes a major source of seed loss in the study area. Burying the seeds 2 cm below the sediment surface prevented seed predation in the laboratory and decreased predation in the field, constituting a way to decrease seed loss during restoration. Shore crabs may act as a key feedback mechanism that prevent the return of eelgrass both by direct consumption of eelgrass seeds and as a predator of algal mesograzers, allowing algal mats to overgrow eelgrass beds. This shore crab feedback mechanism could become self-generating by promoting the growth of its own nursery habitat (algal mats) and by decreasing the nursery habitat (seagrass meadow) of its dominant predator (cod). This double feedback-loop is supported by a strong increase of shore crab abundance in the last decades and may partly explain the regime shift in vegetation observed along the Swedish west coast.

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“…nitida has been described. In addition, a sediment layer might also have additional effects such as preventing the development of marine phytophthora species [58]. …”

Section: Discussionmentioning

confidence: 99%

Seed Predation by the Shore Crab Carcinus maenas: A Positive Feedback Preventing Eelgrass Recovery?

Infantes¹,

Crouzy²,

Moksnes³

2016

PLoS ONE

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“…port infrastructure development and dredging) and natural disturbances (e.g. disease and storms) (Cambridge & McComb, 1984; Short & Burdick, 1996; Wyllie-Echeverria & Ackerman, 2003; Kim et al, 2015; Macreadie et al, 2015; Zhang et al, 2014; Lin et al, 2016; Govers et al, 2016). These issues have led to the recent development of restoration efforts to compensate or mitigate seagrass losses, and to enhance the associated ecosystem services (Shafer & Bergstrom, 2010; Suykerbuyk et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Salinity and temperature significantly influence seed germination, seedling establishment, and seedling growth of eelgrassZostera marinaL.

Zhou

Wang

et al. 2016

PeerJ

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Globally, seagrass beds have been recognized as critical yet declining coastal habitats. To mitigate seagrass losses, seagrass restorations have been conducted in worldwide over the past two decades. Seed utilization is considered to be an important approach in seagrass restoration efforts. In this study, we investigated the effects of salinity and temperature on seed germination, seedling establishment, and seedling growth of eelgrass Zostera marina L. (Swan Lake, northern China). We initially tested the effects of salinity (0, 5, 10, 15, 20, 25, 30, 35, and 40 ppt) and water temperature (5, 10, 15, and 20 °C) on seed germination to identify optimal levels. To identify levels of salinity that could potentially limit survival and growth, and, consequently, the spatial distribution of seedlings in temperate estuaries, we then examined the effect of freshwater and other salinity levels (10, 20, and 30 ppt) on seedling growth and establishment to confirm suitable conditions for seedling development. Finally, we examined the effect of transferring germinated seeds from freshwater or low salinity levels (1, 5, and 15 ppt) to natural seawater (32 ppt) on seedling establishment rate (SER) at 15 °C. In our research, we found that: (1) Mature seeds had a considerably lower moisture content than immature seeds; therefore, moisture content may be a potential indicator of Z. marina seed maturity; (2) Seed germination significantly increased at low salinity (p < 0.001) and high temperature (p < 0.001). Salinity had a much stronger influence on seed germination than temperature. Maximum seed germination (88.67 ± 5.77%) was recorded in freshwater at 15 °C; (3) Freshwater and low salinity levels (< 20 ppt) increased germination but had a strong negative effect on seedling morphology (number of leaves per seedling reduced from 2 to 0, and maximum seedling leaf length reduced from 4.48 to 0 cm) and growth (seedling biomass reduced by 46.15–66.67% and maximum seedling length reduced by 21.16–69.50%). However, Z. marina performed almost equally well at salinities of 20 and 30 ppt. Very few germinated seeds completed leaf differentiation and seedling establishment in freshwater or at low salinity, implying that freshwater and low salinity may potentially limit the distribution of this species in coastal and estuarine waters. Therefore, the optimum salinity for Z. marina seedling establishment and colonization appears to be above 20 ppt in natural beds; (4) Seeds germinated in freshwater or at low salinity levels could be transferred to natural seawater to accomplish seedling establishment and colonization. This may be the optimal method for the adoption of seed utilization in seagrass restoration. We also identified seven stages of seed germination and seedling metamorphosis in order to characterize growth and developmental characteristics. Our results may serve as useful information for Z. marina habitat establishment and restoration programs.

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“…[17][18][19] Numerous new species were recently isolated from forests, streams and irrigation water but their pathogenicity have not been determined. Although Phytophthora species are well known for causing diseases of terrestrial plants, Govers et al,20 reported recently the widespread infection of a common seagrass species, Zostera marina (eelgrass) across the northern Atlantic and Mediterranean by P. gemini Man in't Velf, K. Rosend, Brouwe & de Cock, P. inundata Brasier, Sánch, Hern & Kirk and an unidentified species of Phytophthora threatening the conservation and restoration of vegetated marine coastal systems. The taxonomy of Phytophthora species has been traditionally based on morphological characters, e.g.…”

Section: Phytophthoramentioning

confidence: 99%

The Taxonomy and Biology of Phytophthora and Pythium

Ho¹

2018

JBMOA

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The genera Phytophthora and Pythium include many economically important species which have been placed in Kingdom Chromista or Kingdom Straminipila, distinct from Kingdom Fungi. Their taxonomic problems, basic biology and economic importance have been reviewed. Morphologically, both genera are very similar in having coenocytic, hyaline and freely branching mycelia, oogonia with usually single oospores but the definitive differentiation between them lies in the mode of zoospore differentiation and discharge. In Phytophthora, the zoospores are differentiated within the sporangium proper and when mature, released in an evanescent vesicle at the sporangial apex, whereas in Pythium, the protoplast of a sporangium is transferred usually through an exit tube to a thin vesicle outside the sporangium where zoospores are differentiated and released upon the rupture of the vesicle. Many species of Phytophthora are destructive pathogens of especially dicotyledonous woody trees, shrubs and herbaceous plants whereas Pythium species attacked primarily monocotyledonous herbaceous plants, whereas some cause diseases in fishes, red algae and mammals including humans. However, several mycoparasitic and entomopathogenic species of Pythium have been utilized respectively, to successfully control other plant pathogenic fungi and harmful insects including mosquitoes while the others utilized to produce valuable chemicals for pharmacy and food industry.

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Marine Phytophthora species can hamper conservation and restoration of vegetated coastal ecosystems

Cited by 41 publications

References 66 publications

Seed Predation by the Shore Crab Carcinus maenas: A Positive Feedback Preventing Eelgrass Recovery?

Seed Predation by the Shore Crab Carcinus maenas: A Positive Feedback Preventing Eelgrass Recovery?

Salinity and temperature significantly influence seed germination, seedling establishment, and seedling growth of eelgrassZostera marinaL.

The Taxonomy and Biology of Phytophthora and Pythium

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