Causes of the eelgrass wasting disease: Van der Werff's changing theories

Nienhuis, P.H.

doi:10.1007/bf02334245

Cited by 7 publications

(6 citation statements)

References 15 publications

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“…It would appear from our study that this may indeed be the case and that intertidal species of the genus Zostera may not have been impacted to the extent that was first assumed. There has been some debate concerning the direct causal role of Labyrinthula in the seagrass declines of the 1930s (Rasmussen 1977;Nienhuis 1994;Ralph and Short 2002) but, irrespective of cause, there is no obvious evidence of a genetic bottleneck from the nuclear microsatellite analysis of either species.…”

Section: Discussionmentioning

confidence: 98%

“…Labyrinthula zosterae), results in extensive leaf damage and is believed to have destroyed around 90% of Zostera beds in the north Atlantic (Short et al 1987). Other researchers have suggested that the disease may be a secondary infection of already senescent plants (Nienhuis 1994;Vergeer and Develi 1997), although the ability of the pathogen to infect healthy eelgrass beds has been demonstrated (Ralph and Short 2002). Further theories suggest that climatic change may have been the primary causal agent and that the decline of seagrass beds was coincident with the Labyrinthula outbreak (Rasmussen 1977).…”

Section: Introductionmentioning

confidence: 95%

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The importance of reproductive strategies in population genetic approaches to conservation: an example from the marine angiosperm genus Zostera

Provan

Wilson

Portig³

et al. 2007

Conserv Genet

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Knowledge of the levels of genetic diversity maintained in natural populations can play a central role in conservation programmes, particularly in threatened habitats or species. Fluctuations in population size can lead to loss of variation and, consequently, increase the risk of extinction. We have examined whether such a genetic bottleneck has occurred in populations of two species in the seagrass genus Zostera, which are believed to have been affected by an outbreak of wasting disease at the start of the last century. A test for heterozygote excess at five nuclear microsatellite loci did not suggest the occurrence of a genetic bottleneck, but analysis of seven chloroplast microsatellite loci and sequence data from two regions did suggest a bottleneck in the chloroplast genome. Extremely low levels of between-population diversity suggest that all subpopulations can be treated as a single management unit for each species. Comparable levels of nuclear genetic diversity were found in the three populations of the primarily sexual Zostera marina var. angustifolia studied but a wider range of within-population diversity was found in Zostera noltii, which displays both sexual and vegetative reproductive strategies. This may be due to an increase in sexual recruitment due to localised fresh water inflow into the study site near to the most diverse population. Such populations should be prioritised as source material for any replanting or remediation due to natural or anthropogenic loss of Zostera beds in the area.

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Section: Discussionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 95%

The importance of reproductive strategies in population genetic approaches to conservation: an example from the marine angiosperm genus Zostera

Provan

Wilson

Portig³

et al. 2007

Conserv Genet

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“…Short et al 1988, Nienhuis 1994, Short & WyllieEche verria 1996, few molecular genetic data are available to support taxon identification in endophytic Labyrinthula species associated with seagrasses in general. Using culturing, Vergeer & den Hartog (1994) have convincingly demonstrated that many seagrasses worldwide carry Labyrinthula-like protists inside their tissue, but they only present light microscope data for identification.…”

Section: Discussionmentioning

confidence: 99%

“…In Europe, a Z. marina decline in the Dutch Wadden Sea (Grevelingen lagoon) has been related to L. zosterae infection (Nienhuis 1994 Although protists can only be con clusively identified to species by using appropriate DNA marker sequences (Adl et al 2007), Labyrinthula species have mostly been identified by microscopy (Renn 1936), culture morphology (Vergeer & den Hartog 1994), host damage (the relative area of leaf le sions, i.e. the wasting index; Burdick et al 1993), and infectivity trials (e.g.…”

Section: Introductionmentioning

confidence: 99%

Widespread occurrence of endophytic Labyrinthula spp. in northern European eelgrass Zostera marina beds

Bockelmann¹,

Beining²,

Reusch³

2012

Mar. Ecol. Prog. Ser.

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Seagrasses worldwide are commonly infected by endophytic protists of the genus Labyrinthula. To date, the nature of the interaction of endophyte and host is not well understood. In eelgrass Zostera marina, the endophyte Labyrinthula zosterae may become virulent (pathogenic) and lead to the loss of entire seagrass beds. One of the best known examples of any marine epidemic was a series of outbreaks of the 'wasting disease' on both sides of the Atlantic in the 1930s, but smaller infestations have been reported more recently. Until now, detection of infection by Labyrinthula spp. was based on the wasting index (i.e. the relative area of leaf lesions) or microscopy, while genetic data were virtually absent. We characterized a ~1400 bp portion of the 18S small subunit rDNA in L. zosterae isolates (N = 41) from 6 northern European sites and 1 southern location (Adriatic Sea) in order to assess the identity and potential diversity of endophytic protists. Because there are indications that low salinity impedes Labyrinthula growth, sampling sites included a wide range of salinities from 5 to 34 psu. A search against the non-redundant GenBank database revealed that most isolates are 99% similar to the only L. zosterae 18S sequence available from the database at all but the Finnish site (salinity values 5 to 7 psu). At this site, a different Labyrinthula species occurred, which was also found in fully marine Wadden Sea cultures. A third species was detected in Skagerrak, south-western Baltic and North Sea samples (20 to 25 psu). We conclude that L. zosterae is widespread among northern European eelgrass sites across wide ranges of salinity. KEY WORDS: Labyrinthula infection · Eelgrass · 18S sequence analysis · Salinity · Wasting diseaseResale or republication not permitted without written consent of the publisher

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“…NIENHUIS (1994) gives more details about Van der Werff's microscopical work, including some recent hypotheses, generated by Van der Werff, about the causes of the wasting disease. His microscopical work will only shortly be discussed.…”

Section: Introductionmentioning

confidence: 99%

The dieback ofZostera marina in the 1930's in the Waddensea; An eye-witness account by A. van der Werff

Hartog¹

1994

Netherlands Journal of Aquatic Ecology

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In the archives of the State Institute of Fisheries Research a handwritten report of A. van der Werff on the wasting disease of Zostera marina L. in the Waddensea in 1932 and 1933 is kept. It contains an eye-witness account of the decline of the eelgrass beds. In 1932 the first attack of the disease took place in May and caused heavy devastation. Regeneration started soon, but a second attack at the end of August seemed to destroy the beds definitively. The next year was a year of struggle for the few poorly developed surviving plants. In 1938 the last surviving specimens were seen in the sublittoral.

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Causes of the eelgrass wasting disease: Van der Werff's changing theories

Cited by 7 publications

References 15 publications

The importance of reproductive strategies in population genetic approaches to conservation: an example from the marine angiosperm genus Zostera

The importance of reproductive strategies in population genetic approaches to conservation: an example from the marine angiosperm genus Zostera

Widespread occurrence of endophytic Labyrinthula spp. in northern European eelgrass Zostera marina beds

The dieback ofZostera marina in the 1930's in the Waddensea; An eye-witness account by A. van der Werff

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