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

Eyal Rahav, Ofrat Raveh, Or Hazan, Nurit Gordon, Nurit Kress, Jacob Silverman, Barak Herut

Research output: Contribution to journalArticlepeer-review

Abstract

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.

Original languageEnglish
Pages (from-to)559-567
Number of pages9
JournalMarine Pollution Bulletin
Volume127
DOIs
StatePublished - Feb 2018
Externally publishedYes

Bibliographical note

Funding Information:
We thank the research assistants of the Marine Chemistry Department at IOLR for the nutrient analyses and the crew of the R/V Etziona for their work at sea. We also thank Lilach Baumer for English editing. This work was supported by grants awarded by the Ministry of National Infrastructures, Energy and Water Resources (grant number 3-11519) to E.R, by the Ministry of Environmental Protection (grant number 145–1–2) to N·K, B·H, J.S and E.R, by the Israeli National Monitoring Program to B·H and E.R and by the PERSEUS project (EC Contract 287600) to B.H. This work is in partial fulfillment of the M.Sc. thesis of Ofrat Raveh (Haifa University).

Funding Information:
We thank the research assistants of the Marine Chemistry Department at IOLR for the nutrient analyses and the crew of the R/V Etziona for their work at sea. We also thank Lilach Baumer for English editing. This work was supported by grants awarded by the Ministry of National Infrastructures, Energy and Water Resources (grant number 3-11519) to E.R, by the Ministry of Environmental Protection (grant number 145–1–2 ) to N·K, B·H, J.S and E.R, by the Israeli National Monitoring Program to B·H and E.R and by the PERSEUS project (EC Contract 287600 ) to B.H. This work is in partial fulfillment of the M.Sc. thesis of Ofrat Raveh (Haifa University).

Publisher Copyright:
© 2017 Elsevier Ltd

Keywords

  • Bacterial-production
  • Chlorophyll-a
  • Nutrients
  • Primary-production
  • SE Mediterranean-Sea

ASJC Scopus subject areas

  • Oceanography
  • Aquatic Science
  • Pollution

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