Mark McKay, Long-term Environmental Changes

Understanding the temporal and spatial
development of south Texas bays and estuaries
from a paleoperspective
Mark C. McKay
Coastal and Marine System Science
What is Paleoclimatology?
 It is not “Day After Tomorrow”
 It is a means by which we can use past
Climate/Environmental events to help explain
and:
 Predict/model both past and current events
 7 Billion People
Types of Estuaries
 Positive : Freshwater inputs from all sources exceed
losses to evaporation
 Neutral: Evaporative losses equal freshwater inputs
 Reverse (Inverse): Evaporation exceeds all
freshwater inflows
 Baffin Bay
(Day et al. 2013)
Drought Conditions in Texas
 Palmer Drought Severity Index (PDSI)
 Measures long term and short term water supplies and
demand from evapotranspiration and runoff
 Texas in severe or extreme drought conditions since
October 2011 (TWDB 2012)
 Texas has currently left drought conditions
 Was this a 100, 500, or 1000 year event?
 Texas Catastrophic Drought 1950’s
 Ask California
Baffin Bay Sampling Sites
ENSO North American Monsoon
and the Bermuda High
•
•
•
•
•
Graphic:TWDB
•
Changes in ENSO frequency
• Increased precipitation in
Southeast
NAM: Shift in wind bring moist
air to southwest
Changes in insolation
(obliquity)
These cause changes in NA
and SWM Monsoon
Changes in foraminiferal
population, which reflect
salinity (Buzas-Stephens
(2014)
• Certain Foraminifera
prefer specific salinity
Bermuda High directs cyclonic
weather into GOM
National Drought Picture
Methods and Approaches
 This project will collect multiple sediment core samples
from Baffin bay and subject them to a variety of nondestructive and destructive analysis in order to develop
a long-term record of climate and precipitation events
that have occurred in the area.
Destructive Techniques
 Bulk Density
 Includes percent organic Carbon (Dean 1974)
 Loss on Ignition
 Inorganic Carbon (Heiri and Lemche 2001)
 Microfossil analysis
 Isotopic Techniques (Shells, Foraminifera)
 137Cs and 210Pb via gamma spectroscopy
 δ18O for Precipitation
 TOC/TN
 Δ14/15N
Objective 2: Reconstruct Paleosalinity
patterns based on Microfossil Assemblages
on the decadal scale for the last 1000 +
years
 Southeastern Texas bays and estuaries can be
shown to contain a long-term record of past
salinity levels, which in turn provide a proxy for
changing moisture balance and freshwater
flows in the region.
Sediment Core Photomosaic
0
50
100
150
Important Microfossils From Texas Bays
and Estuaries (From the Cushman
Collection)
Ammonia parkinsoniana
Ostracoda
Elphidium spp.
Quinqueloculina seminula
Microfossil Assemblages
 Foraminifera and Ostracoda
 Ammonia parkinsoniana
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 Prefers Fresh water environments
Elphidium spp.
 Can live in a variety of salinity conditions
Quinqueloculina seminula.
 Prefers hypersaline water
Ammotium salsum (agglutinated species)
 Prefers Fresh Water, not common
3D Modeling with Particle Size
(Buzas-Stephens 2011)
Care to guess what this is?
Baffin Bay Sampling Sites
Preliminary Dating Information
(Raw radio nucleotide sedimentation rate/datation
estimates
Proxy for Freshwater Flows
 Stable Oxygen isotope analysis of foraminiferal tests
and mollusk shells
 δ18O
 Drought and Flood Signals
 Well documented in Lake Systems
 Zonal Flow
 Atmospheric circulation along latitudinal lines
Objective 3: Evaluate the impact or level of
control of global climate on the paleoecology or
paleosalinity of Texas estuaries.
 Large climatic patterns such as ENSO and the North
American Monsoon have affected Texas bays and
estuaries and have left traceable temporal and spatial
information about past climatic patterns.
What records exist?
 North American Drought Index
 Dendrochronology based
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 Several Sources Exist
Speleothems
Pollen
Diatom
Well-validated source for at least past 700 years
Take Home Message: Another
Tool
 Microfossil Assemblage Analysis (Salinity,
Climate Trends, Freshwater flows)
 Isotopic Techniques (Shells, Foraminifera)

137Cs
and 210Pb (Age of sediments and
sedimentation rate)
 δ18O for Precipitation Rates
 History of Climate Teleconnections (ENSO, Mexican
Monsoon, Salinity)