Brine discharge from desalination plants - Impacts on coastal ecology, public perception and public policy (2014-2018)
Karen Lykkebo Petersen, Nadine Heck, Borja Reguero, Armen Hovagimian, Donald Potts, Brent Haddad & Adina Paytan
Department of Earth Science, Ecology & Evolutionary Biology, Environmental Science and the Institute of Marine Sciences, University of California Santa Cruz
The Nature Conservancy, Santa Cruz
Fresh water demand is increasing world wide as populations and agriculture expand and climate change intensify droughts and areal extent of arid regions. Seawater reverse osmosis desalination is a growing solution for the supply of portable water in arid and semi-arid coastal regions, however the effects of brine-effluent discharge associated with this technology on the local coastal environment are not fully constrained. In this study, we use in-situ measurement of water chemistry and some biological indicators collected pre- and post-operation in the coastal area immediately adjacent to the newly constructed Carlsbad Desalination Plant. Data quantify the impacts and changes occurring within the first year post operation. A significant increase in salinity from an ambient 33.3 to 36 is observed in coastal bottom water extending 600 m offshore of the discharge location in the post-operation sampling. Opportunistic polychaetes are dominating the benthic substrate in the impacted area both pre- and post-operation. We tested desalination brine effects on brittle stars in a 5-week long incubation experiment and observed a trend towards slower growth. Our work highlights the difficulties of effective mixing of high-density brine with coastal seawater even in a high wave area and suggests the need for implementation of more effective discharge methods. We further highlight the need for comprehensive coastal monitoring in areas of proposed desalination facilities along with laboratory assessments of key coastal species
Effects of brine and antiscalants on Red Sea hard corals – Potential effects from desalination plants (2016-2018)
Karen Lykkebo Petersen, Edo Bar-Zeev, Eyal Rahav, Oren Levy, Jacob Silverman, Oriya Barzel, Donald Potts & Adina Paytan
Department of Earth Science, Ecology and Evolutionary Biology, Institute of Marine Sciences, University of California Santa Cruz, USA
Zuckerberg Institute of Water Research, Ben-Gurion University of the Negev, Israel
Israel Oceanographic and Limnological Research, Haifa, Israel
Mina and Everard Goodman Faculty of Life Science, Bar-Ilan University, Ramat-Gan, Israel
Institute of Earth Science, Hebrew University of Jerusalem, Israel
Seawater reverse osmosis (SWRO) is becoming an increasingly important source of potable water for arid and semi-arid regions. Continuous discharge of brine-effluent from desalination facilities into coastal waters poses potential negative impacts on local coastal marine habitats. In this study, we examine the impacts of increased salinity and phosphonate (a common additive used in SWRO) addition on three reef-building coral species, Stylophora pistillata, Acropora tenuis and Pocillopora verrucosa, from the Northern Gulf of Aqaba, Red-Sea. Coral nubbins of each species were collected and incubated in triplicates in: 1) unamended controls in ambient salinity (~ 40); 2) 10% above ambient salinity (~ 44); 3) 10% above ambient salinity + phosphonate-based antiscalant (0.2 mg L-1), and 3) unamended controls. Our results indicate a deterioration in the physiology of all coral species tested, showing a clear dependency with the continuous exposure to increased salinity and phosphonates. Corals showed significant lower abundance in the symbiotic algae concentration, protein content and coral-associated heterotrophic bacteria in the treatments in comparison to the control. Furthermore, net O2 production and calcification rates were significantly reduced. These results suggest that coral reefs may be susceptible to SWRO brine discharge. This study would like to call for careful selection of outfall sites setup locations in the vicinity of coral reef ecosystem.
Paleoclimate reconstructions in Cuba inferred from coral core aragonite (2014-)
Daria Sicilliano, Fernando Bretos, Donald Potts, Lindsay Cullen & Karen Lykkebo Petersen
The Ocean Foundation
Ecology and Evolutionary Biology, Department of Earth Science, University of California Santa Cruz
This project seeks to reconstruct climate records from the Caribbean and Cuba of the past ~200 years using coral core aragonite. Further, track the historical land-use inputs (fertilizers etc) to coral reefs.
Effects of nitrate limitation on pigments and fatty acidsin the marine cyanobacterium Synechococcus sp PC7002 (2014)
Karen Lykkebo Petersen, Niels-Ulrik Frigaard
Department of Marine Science, University of Copenhagen, Denmark
Synechococcus sp. PCC 7002 was grown under nitrate-limited conditions (0.24 g NaNO3 L-1) and compared to non-limited conditions (2 g NaNO3 L-1). The composition of carotenoids was measured by HPLC analysis. A method for extracting all of the carotenoid synechoxanthin was developed. Methods were also developed for extracting fatty acids and for analyzing the fatty acids in cell material by HPLC.
A rapid decrease in carotenoids was observed after 24 hours of growth in the nitrate-limited culture. In the nitrate-limited culture, Phycobilisomes (PBS) almost completely disappeared and Chl a and the major carotenoid ß-carotene dropped to about 20-25% of that in the non-limited nitrate culture. The concentration of synechoxanthin was approximately 0.3 – 0.4 mg (g DW)-1 under both nitrate limited and non-limited conditions. Synechoxanthin is an unusual carotenoid because it has two carboxylic acid groups. A small fraction of synechoxanthin (approx. 10%) could only be extracted after alkaline lysis of the cells, which suggests that this fraction may be covalently bound to other cell components via its carboxyl groups. Plastoquinone-9 (PQ-9) remained the same in both conditions probably because it takes part in both photosynthesis and respiration.
The fatty acid analysis showed a difference in the amount and composition of fatty acids between the limited and non-limited culture. The significance of this finding cannot be determined from a single experiment and further work need to be done on this subject to be conclusive.