Cristina Cox Fernandes
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, Durham, NC, 1995
Professional Positions
Instituto Nacional de Pesquisas da Amazonia, Manaus, Brazil, 1986 - present (on leave)
Adjunct Research
Assistant Professor, 2000 - present
Visiting Scientist
University of
Arizona, 1998 - 2000
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 impressive 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?
Rio Madeira
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 Brazilšs 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 Amazonšs 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.
Trawling along the Amazon
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. Some of our long term goals are to: (1) review all of the
genera of this family while taking sexual dimorphism of the species into
account; (2) formulate a new phylogenetic hypothesis for the family; and (3)
understand the evolution of sex dimorphism within Gymnotiformes.
Some electric
fishes
Representative
Publications:
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.
Cox
Fernandes, C. & de
Merona, B. 1988. Lateral migrations of fishes on a floodplain system in the
Central Amazon (Careiro Island - lake Rei), Br. Preliminary analysis. Memoria
de la Soc. Cien. Nat. La Salle. Suplemento 2, Vol. XLVII: 409-432.