ECOTONE PROPERTIES AND INFLUENCES ON FISH DISTRIBUTIONS ALONG

141 Pages·2007·2.07 MB·English

ECOTONE PROPERTIES AND INFLUENCES ON FISH DISTRIBUTIONS
ALONG HABITAT GRADIENTS OF COMPLEX AQUATIC SYSTEMS

A Dissertation
Presented to the Faculty of the Graduate School
of Cornell University
In Partial Fulfillment of the Requirements for the Degree of
Doctor of Philosophy

by
Nuanchan Singkran
May 2007
© 2007 Nuanchan Singkran
ECOTONE PROPERTIES AND INFLUENCES ON FISH DISTRIBUTIONS
ALONG HABITAT GRADIENTS OF COMPLEX AQUATIC SYSTEMS

Nuanchan Singkran, Ph. D.
Cornell University 2007

Ecotone properties (formation and function) were studied in complex aquatic
systems in New York State. Ecotone formations were detected on two embayment-
stream gradients associated with Lake Ontario during June–August 2002, using abrupt
changes in habitat variables and fish species compositions. The study was repeated at
a finer scale along the second gradient during June–August 2004. Abrupt changes in
the habitat variables (water depth, current velocity, substrates, and covers) and peak
species turnover rate showed strong congruence at the same location on one gradient.
The repeated study on the second gradient in the summer of 2004 confirmed the same
ecotone orientation as that detected in the summer of 2002 and revealed the ecotone
width covering the lentic-lotic transitions. The ecotone on the second gradient acted
as a hard barrier for most of the fish species. Ecotone properties were determined
along the Hudson River estuary gradient during 1974–2001 using the same methods
employed in the freshwater system. The Hudson ecotones showed both changes in
location and structural formation over time. Influences of tide, freshwater flow,
salinity, dissolved oxygen, and water temperature tended to govern ecotone properties.
One ecotone detected in the lower-middle gradient portion appeared to be the optimal
zone for fish assemblages, but the other ecotones acted as barriers for most fish
species.
A spatially explicit abundance exchange model (AEM) was developed to predict
distribution patterns of five fish species in relation to their population characteristics
and habitat preferences across the lentic-lotic ecotones on the two freshwater gradients
associated with Lake Ontario. Preference indexes of each target fish species for water
depth, water temperature, current velocity, cover types, and bottom substrates were
estimated from field observations, and these were used to compute fish habitat
preference (HP). Fish HP was a key variable in the AEM to quantify abundance
exchange of an associated fish species among habitats on each study gradient. The
AEM efficiently determined local distribution ranges of the fish species on one
gradient. Results from the model validation showed that the AEM was able to
quantify most of the fish species distributions on the second gradient.
BIOGRAPHICAL SKETCH

Nuanchan Singkran was born in Chantaburi province located in the eastern part of
Thailand. After finishing high school, Nuanchan entered the faculty of Science at
Chulalongkorn University in 1989 for her undergraduate study in Marine Science with
a major in Marine Biology. Study at the Marine Science Department allowed her to
obtain broad knowledge of both applied science and ecology, especially the
relationship between aquatic creatures and environmental conditions along the coastal
zone of Thailand. After graduation, Nuanchan began her career as an environmental
reporter for Thai and English newspapers during 1993–1996. During her career as a
journalist, Nuanchan received a 2nd place award for an environmental article
supporting Eco-Tourism of Thailand in 1993, and the award for outstanding
environmental news reporter from the Environmental Siam Association in 1994.
Nuanchan’s work in the media provided her a unique opportunity to observe various
environmental problems in Thailand. She realized that the deterioration of natural
resources in the country comes primarily from public lack of understanding and
awareness about the environment. Lack of suitable methodologies to solve problems
and weak environmental policy are additionally significant factors that aggravate
environmental problems. Although Nuanchan likes the challenge of media work, she
needed to be engaged more actively in the problem-solving process. She believed that
academic and research work is really the area that would allow her to contribute to
public education and in-depth research on specific issues.
During 1996–1999, Nuanchan obtained scholarships from the Chin Sophonpanich
Foundation for Environment and from the Biodiversity Research Grant to further her
Master’s program in the multidisciplinary Department of Environmental Science,
Chulalongkorn University. Her Master’s thesis was entitled “Species Composition of
iii
Fish in Mangrove Canals as Reflected from Coastal Land Use at Trat Bay, Thailand”.
Her interest in this topic comes from the fact that a large number of fish species (over
2,000 across the country) have been seriously threatened by human activities,
especially the conversion of coastal areas into shrimp farms, urban districts, or
industrial zones, all done without proper management. Her Master’s research using
fish as a biological indicator revealed that improper land use activities altered the
coastal environment, which in turn affected fish and other living communities in
coastal systems in terms of both abundance and species diversity. After completing
her Master’s degree, Nuanchan received a government scholarship to pursue her PhD
program in Natural Resources at Cornell University in Ithaca, New York in 2001. At
Cornell, Nuanchan conducted her dissertation research on influences of ecotone
properties (formation and function) on species distributions over spatial and temporal
scales. Her research work dealt with both empirical and simulation modeling to
determine ecotone formation in complex aquatic systems and ecotone function on fish
species assemblages. Additionally, she used a simulation model to spatially and
temporally forecast distribution of fish species assemblages across aquatic boundaries.
iv
For all fish and other creatures across global boundaries
v
ACKNOWLEDGMENTS

My graduate committee played vital roles throughout the development of my
dissertation research. I am grateful to all of them for giving me the chance to freely
design and follow my research ideas. My committee Chair, Dr. Mark B. Bain, not
only supported me in any situation during my PhD program at Cornell University, but
also shared his philosophy of thinking and was patient in shaping my research work to
continue on the right track. Without his strong academic support and other help, my
graduate study at Cornell University could not have been completed. As one of my
committee, Dr. Patrick J. Sullivan always gave me instructive comments and helpful
suggestions that greatly improved the quality of my research work. His simple
questions, e.g., “Why is an ecotone is important?” and “How many functions can an
ecotone have?” caused me to think deeply, carefully, and quantitatively on my ecotone
study. Prof. Daniel P. Loucks is not just one of my committee, but also one of the best
teachers I have ever had during my lifetime as a student. Although Prof. Loucks said
that he did not know anything about fish and ecology, his contributions to my research
work deserve praise. Following his suggestion to take some core courses in his
department of Civil and Environmental Engineering, I gained more modeling
experience and recovered my mathematical background to achieve my dissertation
research.
The Royal Thai Government and Thai people whose tax money supported me to
study in the USA deserve any credit for my accomplishments. Additionally, my
special thanks are due to the Lake Ontario Biocomplexity Project (Natural Science
Foundation OCE–0083625), the Hudson River Foundation (GF/01/05), and the
College of Agriculture and Life Sciences at Cornell University, which partly
supported my study and research. I thank Prof. Paul A. Delcourt and Prof. Hazel R.
vi
Delcourt for suggesting ecotone analysis; John Young from ASA Analysis &
Communication, Inc. for providing the beach seine fish and habitat data from the
Utilities’ Hudson River estuary monitoring program; John Ladd from New York State
Department of Environmental Conservation for providing the substrate and shoreline
data; and the Cornell University’s Geospatial Information Repository for providing
submerged aquatic vegetation data.
The completion of my graduate program at Cornell University would be
impossible without the warm support and encouragement from friends and
collaborators. I am thankful to Kristi Arend, Takao Kumazawa, Kathy Mills, James
Murphy, Marci Meixler, Emelia Deimezis, Geof Eckerlin, Gail Steinhart, Carol
Steinhart, Geoff Steinhart, and all the other people I cannot name here for their
support and help during my study period at Cornell. I thank my parents and my
husband, Poonrit Kuakul, for their patience and understanding. I am thankful to my
senior friends, Dolina Millar, Bruce Anderson, Wandee Anderson, and some sisters
and brothers from the Taste of Thai restaurant who made my life in Ithaca not so
lonely and never refused to help me in any manner they could.
vii
TABLE OF CONTENTS
Biographical sketch iii
Dedication v
Acknowledgments vi
List of figures ix
List of tables xii
Chapter One Ecotone properties in the freshwater system associated 1
with Lake Ontario, New York.

Chapter Two Ecotone properties in the Hudson River estuary system 26
New York.

Chapter Three An abundance exchange model of fish assemblage 60
response to changing habitat along embayment-
stream gradient of Lake Ontario, New York.

Appendix 2.1. Cumulative abundance and species richness of fish 93
by region (RE) along the Hudson River estuary
gradient (RE1–RE12) from the five power plant
utilities’ Hudson River estuary monitoring program
using beach seine survey during 1974 to 2001.

Appendix 2.2. Multiple functions (aggregator, mediator, soft barrier, 105
and hard barrier) of the ecotones (from all frequencies
of detection) on the Hudson fish species in each time
period during 1974–2001.

Appendix 2.3. Multiple functions (neutral, partly inhibit, and 109
completely inhibit) of the ecotone peripheries (from
all frequencies of detection) on the Hudson fish
species in each time period during 1974–2001.

References 112

viii