Difference between revisions of "Possible causes for breading failure in common terns"

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== Mogelijke oorzaken van slecht broedsucces in de visdiefkolonie bij terneuzen. Stand van zaken en aanbevelingen - 2003 ==
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[[Image: tern met harring.jpg|thumb|left|250px| <div style="text-align: center;"> Common tern © RIKZ (M. Hoekstein)  
[[Image:damaged egg.jpg|thumb|richt|300px| <div style="text-align: center;"> Stranded sperm whale © RIKZ(M. Van De Heuvel)  
 
 
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<u>'''Context of the study'''</u>
 
<u>'''Context of the study'''</u>
  
Since 1997 the Dutch Coastal and Marine institute (RIKZ) monitors the [http://www.vliz.be/docs/Folders/TROPHOSposter%207.pdf coastal breading birds] of the Delta area. One of these breading  birds  is the common tern. In 1994 the colony in Terneuzen was struck by serious signs of illness, while the other colonies in the delta area remained healthy. The number of breading couples decreased strongly, and the [[broedsucces vertaling!!!!]] was terrible: eggs didn't hatch, young birds were diseased and suffered mass casualties.
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Since 1997 the Dutch Coastal and Marine institute (RIKZ) monitors the breading birds of the Delta area. One of these breading  birds  is the common tern. In 1994 the colony in Terneuzen was struck by serious signs of illness, while the other colonies in the delta area remained healthy. The number of breading couples decreased strongly, and the breading outcome was terrible: eggs didn't hatch, young birds were diseased and suffered mass casualties.
In 1999 the signs of illness vanished and the number of breading couples increased again. However, after 2000, the eggs  started to show anomalies (small cracks or bulges), which indicated that the population still hadn't recovered.
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In 1999 the signs of illness vanished and the number of breading couples increased again. However, after 2000, the eggs  started to show anomalies (small cracks or bulges), which indicated that the population still hadn't recovered.<ref name = pub>[http://www.vliz.be/imis/imis.php?module=ref&refid=115476 van den Heuvel-Greve, M.J.; Hoekstein, M.S.J.; Lefèvre, F.O.B.; Meininger, P.J.; Vethaak, A.D. (2003). Mogelijke oorzaken van slecht broedsucces in de visdiefkolonie bij Terneuzen; Stand van zaken en aanbevelingen. Rapport RIKZ, 2003.037: Middelburg, the Netherlands. 38 pp.]</ref>
  
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[[Image:damaged egg.jpg|thumb|right|250px| <div style="text-align: center;"> Dented egg © RIKZ (M. van den Heuvel - Greve)
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</div>]]
 
'''<u>Content of the study</u>'''
 
'''<u>Content of the study</u>'''
  
 
This study investigated possible causes (both ecological as chemical) for the problems in the common tern colony of Terneuzen.
 
This study investigated possible causes (both ecological as chemical) for the problems in the common tern colony of Terneuzen.
  
<u>'''Main results'''</u>
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<u>'''Main results of the study'''</u>
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The study eliminated 2 of 3 hypothetic causes: namely infection by viruses or bacteria and suffocation by certain plants. This leaves chemicals as the only potential cause. Three groups of chemicals have been encountered in higher concentrations in the Terneuzen colony than in other colonies: [[organotin compounds]], [[PBDE|PBDEs]] and "unidentified substances". However further research is necessary to determine which of these 3 groups of substances caused the problems of the common tern colony. <ref name = pub>[http://www.vliz.be/imis/imis.php?module=ref&refid=115476 van den Heuvel-Greve, M.J.; Hoekstein, M.S.J.; Lefèvre, F.O.B.; Meininger, P.J.; Vethaak, A.D. (2003). Mogelijke oorzaken van slecht broedsucces in de visdiefkolonie bij Terneuzen; Stand van zaken en aanbevelingen. Rapport RIKZ, 2003.037: Middelburg, the Netherlands. 38 pp.]</ref>
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As part of the [http://www.vliz.be/projects/inram/ INRAM] project, the eggs of the Belgian common tern colony near Zee-Brugge are also being monitored for contaminants. You can find more information on this through this [http://www.vliz.be/imis/imis.php?module=dataset&dasid=1357 link]
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==References==
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<references/>
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{{author
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|AuthorID=19826
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|AuthorFullName=Daphnis De Pooter
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|AuthorName=Daphnisd}}
  
3 hypothetic causes: infection, toxic plants and chemicals. The first 2 have been eliminated as possibilities.
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[[Category:North Sea]]
2 groups of chemicals have been encountered in increased concentrations (higher than in other common tern colonies) 
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[[Category:Coastal and marine pollution]]
Could have been caused by: organotin compounds, vlamvertragers, "unidentified substances"
 

Revision as of 10:28, 13 March 2013

Common tern © RIKZ (M. Hoekstein)

Context of the study

Since 1997 the Dutch Coastal and Marine institute (RIKZ) monitors the breading birds of the Delta area. One of these breading birds is the common tern. In 1994 the colony in Terneuzen was struck by serious signs of illness, while the other colonies in the delta area remained healthy. The number of breading couples decreased strongly, and the breading outcome was terrible: eggs didn't hatch, young birds were diseased and suffered mass casualties. In 1999 the signs of illness vanished and the number of breading couples increased again. However, after 2000, the eggs started to show anomalies (small cracks or bulges), which indicated that the population still hadn't recovered.[1]

Dented egg © RIKZ (M. van den Heuvel - Greve)

Content of the study

This study investigated possible causes (both ecological as chemical) for the problems in the common tern colony of Terneuzen.

Main results of the study

The study eliminated 2 of 3 hypothetic causes: namely infection by viruses or bacteria and suffocation by certain plants. This leaves chemicals as the only potential cause. Three groups of chemicals have been encountered in higher concentrations in the Terneuzen colony than in other colonies: organotin compounds, PBDEs and "unidentified substances". However further research is necessary to determine which of these 3 groups of substances caused the problems of the common tern colony. [1]

As part of the INRAM project, the eggs of the Belgian common tern colony near Zee-Brugge are also being monitored for contaminants. You can find more information on this through this link

References


The main author of this article is Daphnis De Pooter
Please note that others may also have edited the contents of this article.

Citation: Daphnis De Pooter (2013): Possible causes for breading failure in common terns. Available from http://www.coastalwiki.org/wiki/Possible_causes_for_breading_failure_in_common_terns [accessed on 28-03-2024]