Another serious damage for the
ichthyofauna is the introduction of non-native species.
The
ichthyofauna was mainly discriminated by the presence of the freshwater species (Pimelodus albicans, Parapimelodus valenciennis, and Luciopimelodus pati), anadromous species (Lycengraulis grossidens) and estuarine species (Brevoortia aurea and Micropogonias furnieri).
This site is characterized by freshwater seeps that give hydrologic estuarine conditions and produce an abundance of organic matter (personal observation), which may explain the presence of these species even if salinity is high; furthermore this site is characterized by a high habitat heterogeneity with mangroves and muddy flatland floors that contribute to
ichthyofauna diversification, even for shelter of important species such as "C".
Trophic organization the
ichthyofauna of two semi-lentic environments in a flood plain on the upper Parana River, Brazil.
Hence this species may have a significant negative impact on the native
ichthyofauna and its establishment would undoubtedly represent a great threat for biodiversity conservation.
Tropical and subtropical elements of the BMLC
ichthyofauna are believed to be derived from one of two sources: 1) from remnant populations established as the Baja California Peninsula rifted from the Jalisco region of southwestern Mexico during the Miocene and Pliocene (~4-8 million years ago) and, 2) from the southern Gulf of California via a Tertiary paleochannel between the BMLC and Bahia La Paz (Castro-Aguirre and Torres-Orozco 1993; Sedlock 2003).
Studies on reservoir
ichthyofauna feeding habits are extremely important to understand how fish communities adjust to such drastic environmental transformation, as variation in the ecosystems physical attributes often leads to changes in food resources.
Its
ichthyofauna consists of at least 44 species, with highlight to those belonging to families Characidae, Curimatidae, Anostomidae and Acestrorhynchidae--the latter possibly representing over 10% of the captured total in the reservoir (FRANCISCO GABRIEL NETO, personal communication).
Petrere (1996) reported several effects of the damming upon the
ichthyofauna, the most important ones being related to the isolation of populations and a decrease in the number of migratory species.
Fitch and one of the authors (RWH) collected and initiated the first research on the Chalk Hill
ichthyofauna. We acknowledge his friendship, assistance, and contributions to the study of fossil and Recent fishes.
Although the semi-arid region has a high density of water supply reservoirs (ANA, 2006), studies regarding the diversity and structure of the fish assemblies in these ecosystems are fragmented, recent and scarce (Texeira and Gurgel, 2005; Marinho et al., 2006; Montenegro et al., 2012), and the spatial and temporal patterns of diversity and the abundance of the
ichthyofauna in these ecosystems are unknown.
Studies on parasitic copepods of marine fishes are still scarce in Brazil because of the great diversity of
ichthyofauna in its coastal waters.
