Water Quality in Little Lagoon

Prior Projects

MacIntyre, H.L., “Little Lagoon as an Incubator Site for the Harmful Bloom-Forming Diatom, Pseudo-nitzschia sp.”, Alabama Department of Conservation and Natural Resources, 2005-2006 $24,500

MacIntyre, H.L.: “Purchase and Testing of an AutoLab Underway Nutrient Analyzer for Real-Time Mapping during Harmful Algal Blooms”, Alabama Department of Conservation and Natural Resources, 2006 - 2007 $28,360

MacIntyre, H.L., “A Volunteer Phytoplankon Monitoring Network”, NOAA National Coastal Data Development Center/NOAA Northern Gulf Institute, 2007-2009$34,000

MacIntyre, H.L.: “Potential anthropogenic triggers for toxicity in the Harmful Algal Bloom diatom Pseudo-nitzschia sp. in Little Lagoon, Alabama”, Alabama Center for Estuarine Studies, 2007-2009 $63,185

Total: $150,075

Monitoring program with LLPS

Biweekly monitoring of physical characteristics, nutrients, microalgae and fecal coliform bacteria

Persistent gradients in water quality descriptors

1: Microalgal biomass varies with nutrientsMicroalgal biomass is

highly correlated with total nitrogen and phosphorus

High correlation suggests flushing low relative to growth

No hypoxia yet detected in surface waters

2: Strong seasonal cycle in nutrientsTotal nitrogen (TN) and

phosphorus (TP) are correlated with temperature

Total N and P are not correlated with salinity except at east end of lagoon (Site 1)

3: Nitrate is correlated with freshwater inputsNitrate is available for

plant growth (most TN is not)

Concentrations are highest at east end of lagoon by canal

Freshwater pulses are a source of nitrate

4: Nitrate is high in groundwater

Nitrate concentrations in groundwater are very high

Estimated transport by groundwater to Gulf of Mexico is 50% of transport through Mobile Bay (Dowling et al. 2004)

Murgulet and Tick (2009)

5: Nutrients are also very high in the sedimentsSediment concentrations

are about 1,000 times higher than in water

Annual temperature-dependence in water is typical of release from sediment

6: Lagoon is a hot-spot for a toxic diatom, Pseudo-nitzschia spp.Blooms in lagoon have been toxic but no obvious

domoic acid intoxication/mortality detected

Bloom density is correlated with discharge from Baldwin County aquifer

Liefer et al. (2009)

7: Fecal coliform bacteria are often highA quarter of samples are

over the regulatory threshold (200 colony forming units L-1). Highest values were c. 2,500 CFU L-1

No correlation with temperature, salinity, nutrients, microalgae

Summary

Water quality in Little Lagoon is not seriously compromised. Nutrient levels are comparable to Mobile Bay but there is no evidence for widespread hypoxia.

Microalgal biomass is correlated with nutrient levels. Both groundwater and sediments are likely sources of nutrients.

The lagoon is a hot-spot for a toxic diatom (Pseudo-nitzschia spp.), The blooms are toxic but there is no evidence for intoxication/ecological consequences.

Fecal coliform bacteria are frequently well above regulatory thresholds. Abundance is not correlated with any parameter measured to date.

Questions

What mechanisms underlie variability in nutrients in the lagoon?

What are the most likely origins of the nutrients?

What is the relationship between nutrients, flushing and microalgal community composition (i.e. Pseudo-nitzschia spp. vs other species)?

What are the causes and consequences of toxicity in Pseudo-nitzschia spp?

What are the likely origins of the fecal coliform bacteria?

New Funding

MacIntyre, H.L. and R. Carmichael: “Harmful Algal Bloom Study, Little Lagoon, Baldwin County, Alabama”, Alabama Department of Conservation and Natural Resources, 2005-2006 $25,000

MacIntyre, H.L., A. Ortmann and K. Park: “Residence time as a factor controlling HABs and fecal coliform bacteria in Little Lagoon, Alabama”, NOAA MS/AL Sea Grant, 2010-2012 $441,549

MacIntyre, H.L., W.C. Burnett and B. Mortazavi: “Groundwater discharge, benthic coupling and microalgal community structure in a shallow coastal lagoon”, National Science Foundation (Bio. Oce.), 2010-2013 $752,399

Liefer, J.D.: “Toxicity of Pseudo-nitzschia spp. in Little Lagoon, Alabama”, FDA Gulf Coast Seafood Laboratory, 2010-2011 $40,967

Total: $1,237,415

1: Nutrient Inputs and Cycling

Dr William Burnett (Florida State University) and student: trace groundwater discharge using Ra and Rn radioisotopes

Dr Bezhad Mortazavi (University of Alabama) and student: measure benthic fluxes

…and Microalgal Taxonomy

Dr Hugh MacIntyre (Dauphin Island Sea Lab), Justin Liefer & Lucie Novoveska (University of South Alabama), LLPS: continued monitoring of nutrients and microalgal community composition

2: Nutrient Source

Dr Ruth Carmichael (Dauphin Island Sea Lab): measure 15N/14N (15N) signatures of particulate and dissolved nitrogen to assess likelihood of fertilizer vs other origin

3: Pseudo-nitzschia spp toxicity

Justin Liefer and Dr Alison Roberston (FDA Gulf Seafood Lab): conduct bio-assays for triggers of toxicity and exposure experiments for transport of toxin into food-chain

4: Microbial Source Tracking

Dr Alice Ortmann (University of South Alabama): assay species-specific ribosomal RNA sequences to determine most probable origin of fecal coliforms

Kildare et al. (2007)

5: Circulation and flushing

Dr Kyeong Park (University of South Alabama): mass balance box model of lagoon to estimate residence time and conduct scenario runs

Dr Hugh MacIntyre & Justin Liefer: couple algal growth model to circulation/flushing model

Exchange with GOM (E)

Groundwater input (G)

Fluxes (F)

F + E + G= Change in concentration

Fluxes (F)

Thanks

To:

State and Federal agencies for support

Justin Liefer and Lucie Novoveska

LLPS volunteers

Note: Inputs from other stakeholders to be solicited in a workshop at end of May