title: Toxic effects of increased sediment nutrient and organic matter loading on the seagrass Zostera noltii.
abstract: As a result of anthropogenic disturbances and natural stressors, seagrass beds are often patchy and heterogeneous. The effects of high loads of nutrients and organic matter in patch development and expansion in heterogeneous seagrass beds have, however, poorly been studied. We experimentally assessed the in situ effects of sediment quality on seagrass (Zostera noltii) patch dynamics by studying patch (0.35 m diameter) development and expansion for 4 sediment treatments: control, nutrient addition (NPK), organic matter addition (OM) and a combination (NPK+OM). OM addition strongly increased porewater sulfide concentrations whereas NPK increased porewater ammonium, nitrate and phosphate concentrations. As high nitrate concentrations suppressed sulfide production in NPK+OM, this treatment was biogeochemically comparable to NPK. Sulfide and ammonium concentrations differed within treatments, but over a 77 days period, seagrass patch survival and expansion were impaired by all additions compared to the control treatment. Expansion decreased at porewater ammonium concentrations >2,000 μmol L(-1). Mother patch biomass was not affected by high porewater ammonium concentrations as a result of its detoxification by higher seagrass densities. Sulfide concentrations >1,000 μmol L(-1) were toxic to both patch expansion and mother patch. We conclude that patch survival and expansion are constrained at high loads of nutrients or organic matter as a result of porewater ammonium or sulfide toxicity.
authors: Department of Environmental Science, Institute for Water and Wetland Research, Radboud University Nijmegen, Faculty of Science, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands. Electronic address: lauralgovers@gmail.com.
authors: Laura L
authors: LL
authors: Govers
authors: Department of Environmental Science, Institute for Water and Wetland Research, Radboud University Nijmegen, Faculty of Science, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
authors: Jan H F
authors: JH
authors: de Brouwer
authors: Department of Environmental Science, Institute for Water and Wetland Research, Radboud University Nijmegen, Faculty of Science, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands; Department of Spatial Ecology, NIOZ Yerseke Royal Netherlands Institute for Sea Research, P.O. Box 140, 4400 AC Yerseke, The Netherlands.
authors: Wouter
authors: W
authors: Suykerbuyk
authors: Department of Spatial Ecology, NIOZ Yerseke Royal Netherlands Institute for Sea Research, P.O. Box 140, 4400 AC Yerseke, The Netherlands.
authors: Tjeerd J
authors: TJ
authors: Bouma
authors: Department of Aquatic Ecology and Environmental Biology, Institute for Water and Wetland Research, Radboud University Nijmegen, Faculty of Science, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
authors: Leon P M
authors: LP
authors: Lamers
authors: Department of Aquatic Ecology and Environmental Biology, Institute for Water and Wetland Research, Radboud University Nijmegen, Faculty of Science, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
authors: Alfons J P
authors: AJ
authors: Smolders
authors: Department of Environmental Science, Institute for Water and Wetland Research, Radboud University Nijmegen, Faculty of Science, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
authors: Marieke M
authors: MM
authors: van Katwijk
mesh_terms: D064751:Ammonium Compounds / Q000737:chemistry / Q000633:toxicity; D018533:Biomass; D019015:Geologic Sediments / Q000737:chemistry*; D010710:Phosphates / Q000737:chemistry / Q000633:toxicity; D013440:Sulfides / Q000737:chemistry / Q000633:toxicity; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000633:toxicity*; D035962:Zosteraceae / Q000187:drug effects* / Q000254:growth & development*
chemical_list: D064751:Ammonium Compounds; D010710:Phosphates; D013440:Sulfides; D014874:Water Pollutants, Chemical
keywords: Eutrophication; Joint detoxification; Nutrient; Organic matter; Sulfide toxicity