Transcript Water Quality in Little Lagoon-By Dr. Hugh MacIntyre, DISL, April 2010

Water Quality in Little Lagoon
Prior Projects
MacIntyre, H.L., “Little Lagoon as an Incubator Site for the Harmful BloomForming 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 nutrients
Microalgal 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
nutrients
Total 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 inputs
Nitrate 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 sediments
Sediment concentrations
are about 1,000 times
higher than in water
Annual temperaturedependence 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 high
A 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 Pseudonitzschia 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 (d15N)
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 speciesspecific 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
F+E+G
= Change in concentration
Groundwater
input (G)
Fluxes (F)
Fluxes (F)
Exchange with
GOM (E)
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