Zoogeographic Analysis of the Fish Fauna Associated with Soft Bottoms during El Niño - La Niña (98-99) In San Ignacio Lagoon, Baja California Sur, Mexico Barjau-González E 1* , Galván-Magaña F 2 , Abitia-Cárdenas LA 2 , Moreno-Sanchez XG 2 and Rodríguez- Romero J 3 1 Department of Marine Biology, Autonomous University of Baja California Sur, Apdo. Postal 19-B, La Paz, Baja California Sur, Mexico 2 Department of Fisheries and Marine Biology, National Polytechnic Institute - CICIMAR, PO Box 592 La Paz, Baja California Sur, Mexico 3 Centro Biological Research of the Northwest, Apdo. Postal 128, La Paz, Baja California Sur, Mexico * Corresponding author: Barjau-González E, Department of Marine Biology, Autonomous University of Baja California Sur, Apdo. Postal 19-B, La Paz, Baja California Sur, Mexico, Tel: +52 (612) 123 88 00, extension 4821; E-mail: ebarjau@uabcs.mx Received date: Jun 21, 2014, Accepted date: Aug 01, 2014, Publication date: Aug 15, 2014 Copyright: © 2014 Emelio BG, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Abstract The San Ignacio Lagoon is part of the Vizcaino Biosphere Reserve, a location that has been declared a critical area for the conservation of marine mammals and fish that use it for breeding, feeding and refuge. The present paper has as its main focus to determine the impact of a large-scale oceanographic phenomenon (El Niño/La Niña) on the zoogeographic composition of the community of soft-bottom fish of the San Ignacio Lagoon. During the warm El Niño period of spring and fall 1998, the average water temperatures in San Ignacio Lagoon were between 20.9 and 21.1°C (± 0.2°C), while during the summer of 1998 average temperatures were higher (24.3°C), and during the cold La Niña period of the 1999 winter a 13.4°C average temperature was recorded. Eight species were present during all seasons: Eucinostomus dowii, Hippocampus ingens, Hypsopsetta guttulata, Paralabrax maculatofasciatus, Paralichthys californicus, Sphoeroides annulatus, Sphoeroides lispus and Urobatis halleri. The species with the highest abundance during El Niño were: Paralabrax maculatofasciatus, Eucinostomus dowii; whereas during La Niña the most abundant species were: Sphoeroides lispus, Paralabrax auroguttatus and Sphoeroides annulatus. The recorded fishes had zoogeographic affinity for the following provinces: Panamic (36%), Californian (32%), Eastern Pacific (18%) and Mexican (11%). Eleven fish species of tropical affinity that were recorded during El Niño event of 1997-1998. Keywords: San Ignacio Lagoon; El Niño-La Niña events; Fish fauna; Soft bottoms Introduction The San Ignacio Lagoon is the second largest lagoon on the Pacific coast of Baja California Sur, Mexico (BCS). It is classified zoogeographically as belonging to the Californian Province [1] and is situated within a temperate region. However, during events like El Niño, when there is an influence of tropical waters from the eastern Pacific, and during La Niña, when temperatures are cooler than normal, the presence of species with tropical affinities, or the absence of species adapted to different temperatures, are common. These events occur over irregular intervals of time spanning 2-7 years [2], although the average is about once every 3-4 years [3,4]. The main effects of the El Niño (EN) – La Niña (LN) episodes in the Pacific Ocean are changes in seawater temperatures, seawater levels, current patterns and atmospheric pressures, and interannual variability of the coupled ocean-atmosphere system. Warm surface waters during El Niño years promote an increase in latent heat in the lower atmosphere, and provide good conditions for the development of stronger hurricanes. During La Niña the atmosphere-ocean system conditions are different, and the formation of tropical hurricanes is avoided, thanks to low sea surface temperatures [5]. The effects of changing weather on marine ecosystems are only partially known, but there is evidence of effects on fish populations and fisheries [6-10]. La Niña is known as the anti-Niño, and is characterized by water-cooling. Its impacts on global climate are opposite to those of El Niño [11]. La Niña occurs after some, but not all El Niño episodes, and typically El Niño occurs more frequently than La Niña [12]. The influence of abnormally cool water on fish populations, as well as the effects of El Niño, is still not well understood. The present study was carried out in order to determine changes in the soft-bottom fish populations during these oceanographic events in San Ignacio Lagoon. This paper is the first of its kind in this important coastal lagoon; one of the effects of these phenomena was on the presence/absence of species detected during each event, although eight species were recorded throughout the study. Material and Methods San Ignacio Lagoon is located on the west coast of the Baja California peninsula between 26°43' and 26°58' N, and 113°08' and 113°16' W (Figure 1). It is a shallow lagoon; depths range from 2 to 4 meters, and can be up to 20 meters in the channels that connect the lagoon with the Pacific Ocean [13]. Inside the lagoon there is a system of channels separated by extensive sand bars that are exposed during low tide [13,14]. The coasts are composed of sandy beaches, muddy plains, mangrove forests, wetlands and a few rocky areas. The northern part of the lagoon comprises the main body of water, and a second body of water extends towards the east, and includes most of the mangrove area [15]. Biodiversity, Bioprospecting and Development Emelio et al., J Biodivers Biopros Dev 2014, 1:3 http://dx.doi.org/10.4172/ijbbd.1000123 Research Article Open Access J Biodivers Biopros Dev ISSN: IJBBD, an open access journal Volume 1 • Issue 3 • 1000123