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 The TIDE project is a four-year National Science
Foundation Integrated Research
Challenges in Environmental Biology (IRC-EB) funded study investigating the
long-term fate of coastal marshes in the Plum Island watershed of Northern
Massachusetts. Specifically
this project will look at the interactive effects of nutrient enrichment and
the removal of top level consumers in several small tidal creeks of the
Rowley river.
Research for the TIDE
project will be performed in conjunction with the Plum Island Estuary Long
Term Ecological Research program. The Plum Island LTER was
established in 1998 and now involves over 50 researchers from over 31
institutions nationwide. The PIE-LTER was designed to serve as a long-term
monitoring program for the Plum Island salt marsh ecosystem. Data collected as part of
the TIDE project will contribute to the overall PIE-LTER database and
increase our understanding of how ecosystem components respond to natural and
human-induced changes over time.
 Increased nutrient input to
estuaries from human activities has been a concern to scientists for many
years. In addition to stimulating plant and algal growth, nutrient
fertilization can alter plant species composition and change the
sedimentation and erosion rates that regulate marsh accretion and
decomposition. The presence of higher order animals, such as fish, can
also affect the balance of marsh accretion and loss by influencing the flow
of nutrients within the marsh ecosystem. Through their feeding and behavior,
fish can increase or decrease plant and algae production, increase
decomposition and move nutrients into or out of the marsh ecosystems through
migration. The combined effects of changing nutrient loading and species
composition can result in the building up or sinking of the marsh relative to
sea-level rise. TIDE project will lead to a better understanding of the
processes that drive salt marsh productivity and the role that individual
ecosystem components play in responding to change.
We will use a
combination of field experiments and ecosystem modeling to understand and
predict the effects of decades of nutrient enrichment and species composition
changes on the long-term sustainability of salt marshes. We ask three
questions:
1.) Do moderate levels of nutrient loading stimulate plant growth
more than microbial decomposition?
2.) Can the loss of an abundant fish, the mummichog,
increase the susceptibility of marshes to nutrient enrichment?
3.) Will moderate, long-term nutrient loading have cumulative effects
on salt marshes?
 This study plans to monitor the
ecosystem-wide effects of two experimental manipulations in four tidal creeks
of the Rowley River over a four year timespan.
Nutrients in the form of fertilizer will be added to two creeks and mummichogs, the dominant species of fish, will be removed
from small branches of all four creeks. During these manipulations several
variables will be measured including: water column chemistry, plant and algal
species composition and production, fish and invertebrate population and
abundance, marsh surface elevation, creek metabolism, and the decomposition
rate of peat.
 The TIDE project will help us
understand the long-term, cumulative effects of moderate increases in
nutrients and changes in species on the productivity, food web, and physical
structure of salt marshes. We will use field measurements of changes in marsh
processes to develop an ecosystem model that will predict the cumulative
effects of nutrients and species changes on marshes over decades. Information
on the effects of chronic, moderate levels of nutrients on coastal ecosystems
is needed nationally and locally. Towns in New England
are facing the same issues as thousands of other towns along the Atlantic
seaboard. Because we do not know how salt marshes are affected by chronic
nutrient loading and/or species composition changes, protecting or restoring
these ecosystems for the long-term is difficult. The TIDE project will
contribute needed information that will help to protect the existing healthy
marshes, safeguard fisheries and biodiversity, and restore impacted marshes.
For more information view the letter of intent or the complete proposal.
Acknowledgment
and Disclaimer
"This material is based upon work supported by
the National Science Foundation under Grant No. DEB 0213767 and OCE 9726921.
Any opinions, findings, and conclusions or recommendations expressed in this
material are those of the author(s) and do not necessarily reflect the views
of the National Science Foundation."
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