Justin D. Liefer

1. PHYTOPLANKTON COMMUNITY STRUCTURE AND THE PHYSIOLOGICAL ECOLOGY OF THE TOXIC, BLOOM-FORMING DIATOM PSEUDO-NITZSCHIA SPP. IN COASTAL ALABAMA Justin D. Liefer

2. Outline • Introduction • Interaction with LLPS • Why are we interested in nutrients (nitrogen, phosphorus) • What are harmful algal blooms (HABs) • What is Pseudo-nitzschia • Study Goals and overview of results • Findings • Occurrence Pseudo-nitzschia in Alabama waters • Seasonal patterns in nutrients and grounwater • Seasonal patterns in Pseudo-nitzschia and other phytoplankton • Toxicity of Pseudo-nitzschia • Conclusions

3. Definitions • Algae – • General (and old) term for a wide range of simple organisms that are similar to plants • They do photosynthesis, making their own food using light. Includes seaweeds and phytoplankton • Phytoplankton – • Microscopic, single-celled algae (microalgae) that live in the water column. • They act as the “plants” and base of the food web in oceans and lakes.

4. Disclaimers • The sky is not falling. This work is motivated by general scientific interest (DISL) and understanding of the local environment to help manage and protect it (LLPS) • The presence of toxins in the water or in fish does not mean that poison is imminent or even likely • I am showing interesting biological patterns that contribute to science in general, not assessing ecosystem health or tracking pollution • I am high-lighting potential areas of concern

5. Interaction with LLPS • Volunteers from LLPS have collected bi-weekly samples since June 2007. About 140 sampling trips, almost 1000 samples. • This has greatly assisted our research efforts aside from sampling help • Local access and knowledge • Oppurtunity for community outreach • Educational opportunities • In turn, Little Lagoon is now very well-studied and will soon be well-represented in the scientific literature

6. Why Are We Interested in Nutrients? • Phytoplankton (like plants) need nutrients (fertilizer) to grow. Nutrient inputs can control the amounts and kinds of phytoplankton • Nitrogen (N) and phosphorus (P) are the most important nutrients • Silicate (Si) can also be important (diatoms) • Nutrients can be delivered from outside the system (river or groundwater discharge, runoff, sewage) • Nutrients can be produced internally (nitrogen-fixation, recycling by bacteria) • Difference between total nutrients and dissolved (available)

7. Harmful Algal Blooms (HABs) • A broad term for any proliferation of phytoplankton with potentialnegative consequences for the rest of the ecosystem or human health • An increasing global problem • Nutrient pollution is widely believed to be the cause of this increase • Also due to invasive/exotic species • Can be “harmful” due to: • Production of toxins • Reducing oxygen in the water • Physical damage (like clogging fish gills) geo.brown.edu

8. Pseudo-nitzschia, the toxic diatom • A diatom (a group of phytoplankton) which occurs in temperate waters globally • Can produce the neurotoxin domoic acid (DA). Production of the toxin varies, depends on conditions • DA accumulates in plankton, fish, and shellfish and can poison the animals that eat them • Domoic acid poisoning (DAP) is observed on the US west coast in birds and marine mammals after consuming toxic fish. Contamination often causes costly fishery closures • Amnesic shellfish poisoning (ASP) in humans. • 1987, PEI poisoning event ADPH AP Texas PWD

9. A global concern Occurs in a variety of systems Upwelling systems Estuaries Open ocean Oceanic fronts Similarities in bloom conditions Pulses of nutrients Mixing Likes variable conditions A ruderal (weedy) strategy Features of Pseudo-nitzschia

10. Pseudo-nitzschia in Alabama Pseudo-nitzschia rarely described along NE Gulf Coast Notable exceptions: Liefer et al. 2009; MacIntyre et al. 2011

11. Key Questions • When and where does Pseudo-nitzschia occur in Alabama waters? • What are the seasonal patterns in water conditions and phytoplankton where Pseudo-nitzschia occurs? • What conditions control phytoplankton and promote blooms of Pseduo-nitzschia? • What controls the toxicity of Pseudo-nitzschia? Does the toxin move up the food chain?

12. Overview There is a local “hot-spot” for Pseudo-nitzschia blooms at Little Lagoon. Likely caused by groundwater Groundwater discharge promotes Pseudo-nitzschia blooms at low temps Local Pseudo-nitzschia produces toxin, especially when salinity and light are high, phosphorus and silicate are low Domoic acid accumulates in small fish, even when the toxicity of blooms is low

13. When and where does Pseudo- nitzschia occur in Alabama waters? • Pseudo-nitzchia monitored by Alabama Dept. of Public Health since 2004 • Samples of Pseudo-nitzschia abundance at 7 coastal sites were from 2004 – Oct 2008 were examined

14. AP OB GSP LLP DIPB DIEE GSPB A local hot-spot for Pseudo-nitzschia • Pseudo-nitzschia occurs more frequently and often in greater numbersw at Little Lagoon Pass (LLP) • Little Lagoon is a local hot-spot for Pseudo-nitzschia blooms Liefer et al. 2009

15. Groundwater and Pseudo-nitzschia • Groundwater discharge was the most important factor examined • Styx River is an estimate for local groundwater discharge • Groundwater and Pseudo-nitzschia were highly correlatated from Apr 15-May 15 (bloom season) in each year. Local Groundwater Level

16. Local Hydrogeology • Water table is highest near Little Lagoon • Very high nitrate (important source of nitrogen) in local groundwater • Large local discharge of groundwater/nitrate to Gulf of Mexico • Unlikely that this would not effect the biology of local waters Surface Flow 2/3 of nitrate Groundwater 1/3 of nitrate Dowling et al. 2004

17. Groundwater Discharge is Unique • Very high in nitrogen, low in phosphorus • Diffuse, difficult to measure directly • May add nutrients without large flushing/drop in salinity, unlike rivers • Pseudo-nitzschia was shown to prefer high salinity (30.1 ± 3.2). LLP may have ideal combination of high nutrients and high salinity Submarine Groundwater Discharge River Discharge Nutrients Freshwater

18. Seasonal patterns in phytoplankton and Pseudo-nitzschia • Preliminary work prompted closer look at Little Lagoon • Little Lagoon is a shallow, poorly-flushed coastal lagoon. • No river inputs. Connected to groundwater-fed lakes via canals

19. Determining conditions and phytoplankton dynamics in Little Lagoon Approach • 4 sites monitored bi-weekly from Jun 2007 – Jun 2010. • Temperature, salinity, overall water conditions • Nutrients • Phytoplankton pigments • Pseudo-nitzschia monitored during April 2008 bloom and regularly at 2 sites from Jan 2009 – Jun 2010.

20. Groundwater is the source of freshwater to Little Lagoon • Patterns in freshwater to Little Lagoon follows patterns in groundwater • Surveys for Radon 222 (with W. Burnett, FSU), a conservative groundwater tracer, shows direct groundwater inputs and a high correlation with salinity (R = -0.745)

21. Winter and Spring Low temp High Groundwater Low total nutrients Available nitrogen is higher and variable Summer and Fall High temp Low GW discharge High total nutrients Available nutrient consistently low Two Different Nutrient Seasons Sites 1 3 Salinity Jun 07 Jun 08 Dec 07 Jun 09 Jun 10 Dec 08 Dec 09

22. Two Regimes for Phytoplankton and nutrients Cyanobacteria-dominated Diatom-dominated Mean Chl a (μg l-1) • Winter/spring, diatoms dominate, phytoplankton low • Cyanobacteria dominante, phytoplankton high, oxygen low Benthic nutrient regime GW GW GW Benthic Benthic Benthic GW nutrient regime Sites 1 3 Temperature (°C) Jun 07 Jun 08 Dec 07 Jun 09 Jun 10 Dec 08 Dec 09

23. P Winter and Spring • Nutrients are low, but more of them are available • Groundwater controls salinity and nitrogen • Diatoms dominate Phytoplankon on the bottom Detritus N Groundwater

24. Summer and Fall • Nutrients are high in the lagoon • Nutrients likely come recycling of detritus (dead stufff) • Cyanobacteria (blue-green algae) dominate Phytoplankon on the bottom N P Detritus Groundwater

25. Pseudo-nitzschia Blooms Occur in Winter and Spring Only • GW-dominated periods (blue bars, diatom-dominated periods (yellow bars), toxic Pseudo-nitzschia blooms, and low temperatures all overlap • Does temperature or groundwater+nutrients drive blooms? Pseudo-nitzschia spp. log(cells l-1) ND Temperature (°C) Dec 09 Jun 08 Jun 07 Dec 08 Jun 10 Jun 09 Dec 07

26. Are These Blooms Toxic? • Every bloom so far has produced low/moderate levels of toxin • Example from Apr 2008 • Pseudo-nitzschia high across much of lagoon • Toxicity highest in Gulf • Lower nutrients • High light • High salinity

27. What Cuases The Toxicity? • Others have shown nutrient stress to cause toxicity in Pseudo-nitzschia • My results show the same, but also that light is important • Blooms are likely to be more toxic where water is • Saltier • Clearer • Has less phosphorus and silicate

28. Toxin can move up the food chain 2009 ShorelineBloom • Bloom had low toxicity • Toxin detected in 98% of fish collected during bloom (shoreline seine) • Fish toxicity was low compared to poisonous events in other areas CB

29. Implications of fish toxicity • Bloom of low toxicity was able to transfer toxin to higher trophic levels. Much higher cellular toxicity observed in other local blooms • Most fish collected are not considered primary consumers. Toxin was transferred at least 2 levels up the food chain Fishbase.org Texas PWD Sinh Nhut Nguyen

30. Summary and Implications

31. Low grazing pressureon Pseudo-nitzschia Groundwater discharge at low temps promotes Pseudo-nitzschia blooms Light and nutrient stress promote toxicity N + Disturbance Two seasonal phytoplankton/nutrient Seasons Toxins can move up the food chain

32. Regional considerations • Local geology, population growth, agriculture = higher groundwater nitrate in the future. Risks for future blooms • DA contamination unlikely for shellfish in fresher water (e.g. Mobile Bay oysters) • DA exposure should be considered when relaying oysters or attempting aquaculture in local high salinity waters Nolan et al. 2002 Probability of High Groundwater Nitrate

33. Local health implications • DA may pose a threat to mullet and menhaden fisheries (herbivores) • Most likely threat is to wildlife such as birds or marine mammals • Known to be poisoned in other areas • Consumers of phytoplankton-eating fish • Low dose, chronic exposure is a concern for humans and wildlife Fishbase Sinh Nhut Nguyen Texas PWD C. Pabody Texas PWD

34. Thank You • Justin Liefer, jliefer@disl.org • Check the LLPS website (www.littlelagoon.org) for research updates