Impact of nutrient enrichment on productivity of coastal water along the SE Mediterranean shore of Israel - A bioassay approach

Mar Pollut Bull. 2018 Feb;127:559-567. doi: 10.1016/j.marpolbul.2017.12.048. Epub 2017 Dec 23.


The coastal waters of the southeastern Mediterranean-Sea (SEMS) are routinely enriched with naturally-occurring and anthropogenic land-based nutrient loads. These external inputs may affect autotrophic and heterotrophic microbial biomass and activity. Here, we conducted 13 microcosm bioassays with different additions of inorganic NO3-(N), PO4-(P) and Si(OH)4-(Si) in different seasons along the Mediterranean coast of Israel. Our results indicate that cyanobacteria are mainly N-limited, whereas N or Si (or both) limit pico-eukaryotes. Furthermore, the degree to which N affects phytoplankton depends on the ambient seawater's inorganic N and N:P characteristics. Heterotrophic bacteria displayed no response in all treatments, except when all nutrients were added simultaneously, suggesting a possible co-limitation by nutrients. These results contrast the N+P co-limitation of phytoplankton and the P-limitation of bacteria in the open waters of the SEMS. These observations enable the application for a better science-based environmental monitoring and policy implementation along the SEMS coast of Israel.

Keywords: Bacterial-production; Chlorophyll-a; Nutrients; Primary-production; SE Mediterranean-Sea.

MeSH terms

  • Autotrophic Processes
  • Biological Assay
  • Biomass
  • Cyanobacteria / growth & development
  • Environmental Monitoring / methods*
  • Heterotrophic Processes
  • Israel
  • Mediterranean Sea
  • Microbiota / drug effects*
  • Nitrogen / analysis*
  • Phosphorus / analysis*
  • Phytoplankton / growth & development
  • Seasons
  • Seawater / chemistry
  • Seawater / microbiology*
  • Silicates / analysis*


  • Silicates
  • Phosphorus
  • Nitrogen