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Cristina Cox Fernandes
Adjunct Assistant Professor and Curator of Fishes
cristina@bio.umass.edu
Natural History Collections
Education
B.S., Universidade Gama Filho, Rio de Janeiro Brazil, 1982
M.Sc., Instituto Nacional de Pesquisas da Amazonia, Manaus, Brazil, 1989
Ph.D., Duke University, 1995
Professional Positions
Instituto Nacional de Pesquisas da Amazonia, Manaus, Brazil, 1986 - present (on leave)
Visiting Scientist, University of Arizona, 1998 - 2000
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Research Interests
My work focuses on the ecology and evolutionary diversity of neotropical freshwater fishes, particularly within the Amazon River basin.
Neotropical fishes make up a significant percentage of the world freshwater icthyofauna, with new species being described
at an impressvie rate. Much of my research aims to provide basic information about these fishes, from behavior and ecology,
to taxonomy and sexual dimorphism, especially within the Gymnotiformes (electric fishes).
A hallmark feature of Amazonian fish is that they adapt to extreme seasonal changes in habitat
properties such as water level, oxygen availability, and space. I have a long-standing interest in
one such adaptation--lateral migration--in which fishes swim away from floodplains when conditions are
poor and return when conditions improve. This appears to be a basic and widespread adaptation, occurring
in at least 20 Amazonian species. In my studies of lateral migration I have used various approaches
including direct observations and capture of migrating fishes, interviews with subsistence and
commercial fisherman, assessment of habitat quality, and evaluation of fish physiological and
reproductive condition. One of the significant results from my work concerns intrapopulation
variation in behavior; I have found that some individuals of a population engage in a reproductive
migration, returning immediately to the same floodplain area, while other individuals migrate in what
appears to be a dispersal event. This work raises additional questions that I would like to pursue,
such as: What factors trigger lateral and longitudinal (upstream and downstream) migrations in Amazonian
fishes? Do lateral migrations initiate longitudinal migrations? How do fishes choose a floodplain
habitat at the end of their longitudinal migrations? What are the effects of
dispersion migrations on gene flow within these species?
My work also examines the large-scale ecology and distribution of benthic fishes across the Amazon
basin. Since 1992 I have been involved in a project entitled 'Fish Diversity of the Principal Channels
of the Amazon River' (Calhamazon), funded by the National Science Foundation and Brazil’s Conselho
Nacional de Pesquisas. In this project, our group (headed by John G. Lundberg) trawled sections of the
main Amazon river channel (about 3,500 km) including in the lower reaches of the Amazon’s major
tributaries. We are documenting a remarkable abundance and diversity of fishes, over 360 species,
most of which are catfishes and electric fishes, and several of which are new to science.
This project has provided an immense data set for the quantitative study of the community ecology
of these fishes. One of my findings is that distribution, diversity and community structure of the
43 electric fish species in these rivers are strongly influenced by the location of tributaries,
and by the physiochemical features of the water. For instance, we have found that tributaries
enrich the species diversity and composition of Amazon mainstem electric fish communities,
particularly in the westernmost white water tributaries. The diversity appears to increase
immediately downstream of tributaries. Also, we have found that some families of electric fish,
such as the Apteronotidae, are particularly abundant in 'white' waters, while others, such as
the Sternopygidae, are most abundant in 'clear' and 'black' waters. I plan to assess the
community structure of other benthic fish groups as well in the near future.
Another part of my present work examines the taxonomy of Gymnotiformes (electric fish), a group that
comprises over 100 species. My interest in the taxonomy of this group was initially geared towards
species identification, for my work on community ecology. As part of my training I have visited all
of the electric fish collections in the United States and Brazil, and have been regularly collecting
new specimens in central Amazônia. With colleagues I have recently described a new genus of electric
fish with two species. I have also discovered a pronounced morphological sexual dimorphism in several
species in the family Apteronotidae, the most diverse family of Gymnotiformes. Males of these species
exhibit unusually long snouts, which had led them to be classified initially in genera separate from the
females. I discovered this dimorphism while examining the gonads of museum specimens, when I realized
that all of the hypermorphic individuals were male. Another case of a taxonomic error resulting from
sexual dimorphism occurred in the genus Oedegmognathus, in which fishes with teeth outside of their mouths
had been initially classified in one genus, whereas individuals without this character had been
classified erroneously as part of another genus. Fishes with teeth outside of their mouths turn out to
all be males. Another species in the Apteronotidae family was recently studied by a colleague
(Eric Hilton) and I, for which we have described the osteological bases for sexual dimorphism.
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Representative Publications
Hilton, E. & Cox Fernandes, C. Sexual Dimorphism in "Apteronotus" bonapartii
(Castelnau, 1855) (Gymnotiformes: Apteronotidae). Copeia 2006.
Py-Daniel, L. R. & Cox Fernandes, C. 2005. Dimorfismo sexual em Siluriformes e Gymnotiformes
(Ostariophysi) da Amazônia. Acta Amazônica Vol. 35(1)2005: 97-110.
Fernandes, C.C., Podos J. & Lundberg, J.G. 2004. Amazonian Ecology: Tributaries Enhance the Diversity of Electric Fishes. Science 305:
1960-1962.
Buhrnheim, C.M. & Cox Fernandes, C. 2003. Structure of fish assemblages in Amazonian rain-forest
streams: effects of habitats and locality. Copeia 2003 (2): 255-262.
Cox Fernandes, C., Lundberg, J.G. & Riginos, C. 2002. The largest of all electric-fish snouts:
hypermorphic facial growth in male Apteronotus hasemani, and comments on the nominal species A. anas
(Gymnotiformes: Apteronotidae). Copeia 2002 (1): 52-61.
Buhrnheim, C.M. & Cox Fernandes, C. 2001. Seasonal variation of fish communities in Amazonian
rain forest streams. Ichthyological Exploration of Freshwaters 12(1): 65-78.
Cox Fernandes, C. 1999. Detrended canonical correspondence analysis (DCCA) of the electric fish
assemblages in the Amazon. Proceedings of the International Symposium of Biology of Tropical Fishes.
Ed. A. L. Val and V. M. F. Almeida-Val. Chapter 3, INPA, Manaus.
Cox Fernandes, C. 1998. Sex-related morphological variation in two species of apteronotid fishes
(Gymnotiformes) from the Amazon River basin. Copeia 1998 (3): 730-735.
Cox Fernandes, C. 1997. Lateral migrations of fishes in Amazon floodplains. Ecology of
Freshwater Fish 6: 36-44.
Lundberg, J. G., Cox Fernandes C., Albert J. S. & Garcia, M. 1996. Magosternarchus, a new genus with
two new species of electric fishes (Gymnotiformes: Apteronotidae) from the Amazon River basin, South
America. Copeia 1996 (3): 657-670.
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