Vulnerability of Zostera marina seedlings to physical stress

T. Valdemarsen, Paula Canal-Vergés, E. Kristensen, M. Holmer, M. D. Kristiansen, M. R. Flindt

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Eelgrass coverage in Odense Fjord (Denmark) has declined by 90% since 1983, due to eutrophication and its associated pressures, and the state of low eelgrass coverage has remained stable despite 10 to 15 yr of reduced nutrient loading and improved water quality. We hypothesize that the survival of eelgrass seedlings, and thus recolonization through reproductive dispersal, is negatively affected by physical disturbances. The 3 most likely physical mechanisms involved are uprooting or burial through drifting macroalgae, Arenicola marina sediment reworking and current-driven sediment resuspension. Our hypothesis was tested by field observations during the summer of 2009, when the mortality of seedlings was followed through time. The density of seedlings decreased dramatically by 80% during the first month of observations, and no seedlings survived past August, corresponding to an average seedling mortality of 1.5% d(-1). This was > 3 times higher than the mortality for seedlings protected from physical disturbance by enclosures (0.4% d(-1)), indicating that physical disturbance contributed to high seedling mortality. A significant correlation (p = 0.02) between macroalgal drift and seedling mortality suggested that similar to 40% of seedlings were lost due to the physical disturbance of drifting algae. In contrast, no correlations were found between A. marina reworking or resuspension and seedling mortality, despite a mobility of up to 400 cm(3) sediment m(-2) d(-1) by these mechanisms. Given the observed intensity of macroalgal drift, we speculate that this mechanism severely hampers eelgrass reestablishment in certain parts of Odense Fjord.
Original languageEnglish
JournalMarine Ecology - Progress Series
Volume418
Pages (from-to)119-130
ISSN0171-8630
DOIs
Publication statusPublished - 2010
Externally publishedYes

Keywords

  • Aquatic Science
  • Ecology
  • Ecology, Evolution, Behavior and Systematics
  • Arenicola marina
  • Bedload transport
  • Eelgrass
  • Fucus sp.
  • Macroalgal drift
  • Resuspension
  • Reworking
  • Sediment
  • bedload
  • dispersal
  • environmental stress
  • eutrophication
  • fjord
  • hypothesis testing
  • macroalga
  • mortality
  • physical disturbance
  • population decline
  • recolonization
  • resuspension
  • reworking
  • seagrass
  • sediment transport
  • seedling establishment
  • survival
  • vulnerability
  • water quality
  • Denmark
  • Fyn
  • Odense Fjord
  • Syddanmark
  • algae
  • Fucus
  • Zostera marina
  • current-driven resuspension
  • macroalgal drift
  • physical stress
  • reproductive dispersal
  • seedling density
  • seedling mortality
  • Algae Plantae (Algae, Microorganisms, Nonvascular Plants, Plants) - Phaeophyta [14300] Fucus vesiculosus species brown algae common
  • Annelida Invertebrata Animalia (Animals, Annelids, Invertebrates) - Polychaeta [65500] Arenicola marina species
  • Monocotyledones Angiospermae Spermatophyta Plantae (Angiosperms, Monocots, Plants, Spermatophytes, Vascular Plants) - Potamogetonaceae [25400] Zostera marina species eelgrass common seedling
  • 07506, Ecology: environmental biology - Plant
  • 07508, Ecology: environmental biology - Animal
  • 07512, Ecology: environmental biology - Oceanography
  • 12002, Physiology - General
  • 51510, Plant physiology - Growth, differentiation
  • 51526, Plant physiology - General and miscellaneous
  • 64030, Invertebrata: comparative, experimental morphology, physiology and pathology - Annelida
  • Ecology, Environmental Sciences
  • Chemical Coordination and Homeostasis
  • Marine Ecology
  • ECOLOGY
  • MARINE
  • OCEANOGRAPHY
  • POSIDONIA-OCEANICA
  • MACROALGAL BLOOMS
  • INTERTIDAL EELGRASS
  • ADVECTIVE TRANSPORT
  • EUTROPHIC ESTUARY
  • ARENICOLA-MARINA
  • COASTAL WATERS
  • PATCH DYNAMICS
  • NORTH-CAROLINA
  • CHESAPEAKE BAY

Cite this

Valdemarsen, T., Canal-Vergés, P., Kristensen, E., Holmer, M., Kristiansen, M. D., & Flindt, M. R. (2010). Vulnerability of Zostera marina seedlings to physical stress. Marine Ecology - Progress Series, 418, 119-130. https://doi.org/10.3354/meps08828