Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
When Zostera marina is intermixed with Ulva, its photosynthesis is reduced by increased pH and lower light, but not by changes in light quality
Stockholm University, Faculty of Science, Department of Botany.
University of Dar es Salaam, Department of Molecular Biology and Biotechnology.
Stockholm University, Faculty of Science, Department of Botany.
(English)In: Aquatic Botany, ISSN 0304-3770, E-ISSN 1879-1522Article in journal (Refereed) Submitted
Abstract [en]

In eutrophic coastal waters, seagrasses often become intermixed with opportunistic algae, such as different species of Ulva that grow on top of, or between shoots in Zostera marina beds. When this occurs, the algae can both reduce the amount of light reaching the seagrasses and also alter the quality of that light so that it becomes dominated by the green part of the spectrum. Since Ulva has an efficient photosynthetic carbon uptake, its photosynthesis can drastically increase the pH of the surrounding seawater, and thus create conditions where Zostera marina is unable to acquire inorganic carbon (Ci). To evaluate the effects of Ulva on the photosynthetic capacities of the temperate seagrass Zostera marina, we compared it in the laboratory under normal light and light filtered through layers of Ulva intestinalis, and repeated the experiments with the addition of pH-induced changes in carbon speciation and availability. One thallus of Ulva reduced photosynthetically available irradiance to underlying seagrass by about 50% and shifted the quality of remaining light towards the green part of the spectrum. Interestingly, there was no significant difference in photosynthetic performance between Zostera marina under normal light and under Ulva-filtered green light when adjusted to the same irradiance as for the control plants, indicating that the green spectrum transmitted through Ulva layers may be efficient in driving photosynthesis in the seagrass bed. On the other hand, algae-generated pH shifts had drastic negative effects on the photosynthesis of the seagrass.

Keyword [en]
Eutrophication, Inorganic carbon, Light quality, pH, Photosynthesis, Zostera marina
National Category
Biological Sciences
Research subject
Plant Physiology
Identifiers
URN: urn:nbn:se:su:diva-55865OAI: oai:DiVA.org:su-55865DiVA: diva2:409103
Available from: 2011-04-07 Created: 2011-03-30 Last updated: 2017-12-11Bibliographically approved
In thesis
1. Seagrasses and Eutrophication: Interactions between seagrass photosynthesis, epiphytes, macroalgae and mussels
Open this publication in new window or tab >>Seagrasses and Eutrophication: Interactions between seagrass photosynthesis, epiphytes, macroalgae and mussels
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Seagrass meadows are highly productive, ecologically and economically valuable ecosystems. However, increased human activities along the coastal areas leading to processes such as eutrophication have resulted in the rapid loss and deterioration of seagrass ecosystems worldwide. This thesis focuses on the responses of seagrasses to increases in nutrients, subsequent increases in ephemeral algae, and changes in the physical-chemical properties of seawater induced by interaction with other marine biota. Both in situ and laboratory experiments conducted on the tropical seagrasses Cymodocea serrulata and Thalassia hemprichii revealed that increased concentrations of water column nutrients negatively affected seagrass photosynthesis by stimulating the growth of the epiphytic biomass on the seagrass leaves. Interaction between seagrasses and other marine organisms induced different responses in seagrass photosynthesis. Ulva intestinalis negatively affected the photosynthetic performance of the temperate seagrass Zostera marina both by reducing the light and by increasing the pH of the surrounding water. On the other hand, the coexistence of mussels Pinna muricata and seagrass Thalassia hemprichii enhanced the photosynthetic activity of the seagrass, but no effect on the mussels' calcification was recorded. This study demonstrates that seagrass productivity is affected by a multitude of indirect effects induced by nutrient over-enrichment, which act singly or in concert with each other. Understanding the responsive mechanisms involved is imperative to safeguard the ecosystem by providing knowledge and proposing measures to halt nutrient loading and to predict the future performance of seagrasses in response to increasing natural and human perturbations. 

Place, publisher, year, edition, pages
Stockholm: Department of Botany, Stockholm University, 2011. 44 p.
Keyword
CO2, epiphytes, eutrophication, mussels, pH, Photosynthetic activities, seagrasses, Ulva
National Category
Botany
Research subject
Plant Physiology
Identifiers
urn:nbn:se:su:diva-55808 (URN)978-91-7447-250-9 (ISBN)
Public defence
2011-05-06, Föresläsningssalen, Botanicum, Lilla Frescativägen 5, Stockholm, 13:00 (English)
Opponent
Supervisors
Projects
Swedish Agency for Research Cooperation (Sida/SAREC) marine bilateral programme
Note
At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Papers 1, 3 and 4: Submitted. Paper 2: Manuscript.Available from: 2011-04-14 Created: 2011-03-29 Last updated: 2011-04-13Bibliographically approved

Open Access in DiVA

No full text

Search in DiVA

By author/editor
Mvungi, Esther F.Björk, Mats
By organisation
Department of Botany
In the same journal
Aquatic Botany
Biological Sciences

Search outside of DiVA

GoogleGoogle Scholar

urn-nbn

Altmetric score

urn-nbn
Total: 81 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf