MARINE ECOLOGY - PROGRESS SERIES Vol. 49: 215-230, 1988 Published November 30 Mar. Ecol. Prog. Ser. Ecology of three sea catfishes (Ariidae) in a tropical coastal ecosystem - Southern Gulf of Mexico* Alejandro Yaiiez-Arancibia, Ana Laura Lara-Dominguez Instituto de Ciencias del Mar y Lirnnologia, Universidad Nacional Autonoma de Mexico, Apartado postal 70305, 04510 Mexico, Distrito Federal, Mexico ABSTRACT: Catfishes of the Family Ariidae are characterized as eurythermal and euryhallne inhabit- ants of estuarine waters. In the Southern Gulf of Mexico (Terminos Lagoon) there are 3 species: Arius felis, A. melanopus, and Bagre rnarinus. Juveniles of A. melanopus occur in the fluvial-lagoon system (FLS) in areas with oysters Crassostrea virginica, while adults occur throughout the lagoon. A. melanopusreaches sexual maturity at 160 mm total length (TL) and reproduces in FLS in salinities < 12 ppt, temperatures 2 35 "C and high turbidity waters. Males of 160 to 222 mm TL with eggs and/or embryos in their mouths are abundant in August and September, after which they migrate towards areas of greater salinity, lower temperature and less turbidity Juveniles recruit towards the western inlet (estuarine) and central basin of the lagoon. The reproduclve pattern of A. felis is the inverse of A. melanopus. Juveniles are found in areas of hgher salinity in the lagoon, and adults occur throughout the lagoon. The species matures sexually after reaching 200 mm TL and reproduces in salinities > 12 ppt, temperatures 2 30 "C, and in less turbid areas dominated by Thalassia testudi~~ummeadows. Males with eggs and/or embryos in their mouths are found In September. After the incubation period adults migrate toward the eastern inlet (marine)and luveniles toward the western inlet (estuarine).B. marjnus is found only in the western inlet (estuarine),central basin, and FLS of Terminos Lagoon. This specles reproduces along the coastline and enters the lagoon at the end of the rainy and winter storm or nortes season. Juveniles use the lagoon as nursery area. The Terminos Lagoon has a high diversity of habitats due to ecological interchange with rivers, swamps and the inner shelf. Three main strategies in the use of the system by catfishes in relation to reproduction and feeding may be characterized as: (1) spawning in the rivers and swamps followed by a migration of juveniles toward the central part of the estuarine system; (2) spawning in the estuarine system; and (3) spaw~ngin the sea followed by migration of juveniles to the FLS for feeding. Estuarine fish that have separate reproduction, growth, and feeding areas generally occur in great abundance and have adapted by reducing interspecific competition and temporal and spatial niche partition. In tropical high diversity ecosystems, biological cycles are closely related to high productivity of coastal waters, large supply of organic matter, increased food availability, and protection from predators. The estuary-inner shelf or swamp-estuary migrations can be interpreted as small-scale anadromous adaptations. INTRODUCTION Mexico, including our study area, there are 3 species: in order of abundance Arius melanopus, A. felis and Bagre In tropical and subtropical America the family Ariidae marinus (e. g. Yafiez-Arancibia et al. 1976, Amezcua is one of the most abundant fish groups in coastal lagoons Linares 1977, Yafiez-Arancibia 1978, Yanez-Arancibia and estuaries. For example, on the Mexican Pacific coast et al. 1980, Lara-Dominguez et al. 1981). there are 13 species. Of these, Galeichtys (= An'us) Results of a number of studies indicate that sea caerulescens is the most abundant, while in the Gulf of catfishes are among the most abundant fishes in the Gulf of Mexico coastal zone (Sheridan et al. 1984, Deegan & ' Thompson 1985). Their morphological, reproductive, Contribution No. 456 from the Institute of Marine Sciences feeding, and migratory adaptations are closely linked to and Lmnology, Universidad Naclonal Autonoma de Mexico. Presented at the international symposium 'Comn~on physical processes and the heterogeneity of habitats in Strategies of Anadromous and Catadromous Fishes', Boston, estuarine lagoon systems. In the coastal zone, from USA, March 9-13, 1986, Am. Fish Soc. swamps and marshes to the inner shelf, there are coastal O Inter-Research/Pnnted In F. R. Germany 216 Mar Ecol. Prog. Ser. 49. 215-230, 1988 lagoons and estuaries with permanent resident, migra- Puerto Real Inlet, to the west and east respectively of tory, cyclical, and occasional visitor species. This great Carmen Island) connect the lagoon to the sea (Fig. l), variety of life cycles indicates that estuarine fishes play and there is a strong westerly flow of water caused by an important role in the ecology of these ecosystems as a the predominantly southeasterly winds. Because of this form of energy storage within the ecosystem, and as circulation pattern, there are semipermanent gradients transformers and regulators of energy (Yanez-Arancibia of salinity, turbidity, nutrient levels, and sediment & Nugent 1977, Deegan & Thompson 1985, Yanez- types (Yanez-Arancibia & Day 1982, Yanez-Arancibia Arancibia 1985). The diurnal and seasonal utilization of et al. 1983). There are 3 climatic periods, the rainy these ecosystems by fish, together with separation of the season from June to September, the winter storm (nor- habitats for different life historystages, contributes to the tes) season from October to January, and the dry sea- high diversity in tropical estuaries. son from February to May. The southern part of the The objectives of our study on Anus felis, A. lagoon receives freshwater (6 X 10' m3 yrpl) from 3 melanopus, and Bagre marinus were (1) to determine main rivers. There is a great diversity of estuarine and compare the spatial-temporal pattern of distribu- habitats, including high and low salinity mangrove tion and abundance; (2) to establish time and place of swamps, seagrasses, marshes, high sedimentation spawning; and (3) to establish feedings habits. These areas, oyster reefs, and a mesohaline central basin. data are evaluated in relation to habitat requirements Five ecological areas are outlined in Fig. 1 and Table 1. of each species. Data on sea catfishes may be relevant Salinity is high (up to 30 %o) in the north and northeast for understanding the small-scale anadromy in tropical of the lagoon during the dry season. Benthic macroin- coastal ecosystems. Moreover, sea catfishes are species vertebrates and fish assemblages are specific for each with estuarine perspectives for future aquaculture. habitat and are controlled by salinity, fluvial input, turbidity and sediment types, detailed information on which is presented by Yaiiez-Arancibia & Day (1982) STUDY AREA and Yanez-Arancibia et al. (1980, 1982, 1983). Terminos Lagoon is a large (ca 2500 km2),shallow (X = 3.5 m) lagoon in the Southern Gulf of Mexico border- METHODS ing Campeche Sound. The climate is humid tropical with an annual rainfall of 1100 to 2000 mm, and tidal Field activities. Fish were collected with a 5 m range is 0.3 to 0.7 m. Two inlets (Carmen Inlet and shrimp trawl (mouth opening while fishing was 2.5 m; Fig. 1. Terminos Lagoon in the Southern Gulf of Mexico with the 5 habitats proposed for the estuanne lagoon ecosystem (see Table 1). Fish collection stations [lto 18 plus Estero Pargo Inlet (ESP) and Puerto Real 35 *I Inlet (PRI)] are shown for 1980 to 1982. Graphs show spatial variation in transparen- cy (Ok) and salinity (ppt) in the 5 lagoonal habitats. Temporal variations in temperature ( C) and sal~nlty(ppt) are adapted from Day et al. (1C)82).Yanez-Arancibia & Day (1982), and Yancz-Arancibia et al. (1983) HABITATS MONTHS Table 1 Maln ecological charactenstics of habitats In Terminos Lagoon (from Yanez-Aranc~b~aet al. 1983) Habltats Salinity (%o) Transparencyh (%) Water influenceC Observations (Fig. 1) Mean (CV, '/U)" Mean (CV, %)" Sea Fresh ECI Inner littoral of Carmen I+ Strong seawater influence. Similar to Habitat CB durlng Island dry season. Sand and silty-clay wlth 30 to 7OC%CaC03. Macroalgae seagrass meadows and mangrove swamps CB Central Basln 2+ Transition zone. Simllar to Habltat ECI during dry season and to Habitat FLS In nortes and ralny seasons. Muddy with [ine sand and clay-silly with 30 to 40"/0 CaC03. Macroalgae FLS Fluvial Lagoon Systems 4+ Strong riverine ~nfluence.Similar to Habltat CB dunng Eastern (FLS 1) dry season. Silty-clay with fine sand with 20 to 30% CaC03. Seagrass meadows, mangrove swamps and oys- ter reefs Western (FLS 2) 4+ Similar to Habit-at C1 during dry season. Sllty-clay wlth 20 to 30 % CaCOJ. Mangrove swamps and oyster reefs. During nortes and rainy season FLS 1, FLS 2 are simllar to Habitat CB C1 Carmen Inlet 3+ Variable zone due to marine and freshwater ~nteractlons. Similar to Habitat FLS 2 dunng dry season and to Habitats ECI and CB during nortes and rainy seasons. Clay-silty with less than 30% CaCO:,. hdangrove swamps and macroalgae debris PR1 Puerto Real Inlet l+ Predominantly marine due to the net flow of the Gulf of Mexico water toward the lagoon. Slmllar to Habitat ECI and with CB during dry season. Sand and s~lty-claywlth 50 to 70%" CaC03. Macroalgae, seagrass meadows, and mangrove swamps " CV: Coefficient of Variation = 100 SD/mean h Transparency has been estimated and related to the depth by T = (t/d)100 (where T = percentage of transparency; t = llght penetration lnto the water column, d = depth during each event) ' Magnitude of influence = 1+ to 4 + 218 Mar. Ecol. Prog. Ser. 49: 215-230, 1988 19 mm mesh), with drags of 10 to 12 min at 2 to 2.5 delimited by the gravimetric percentage, the percent- knots; individuals trawls covered an area of 1500 to age of frequency of occurrence, and the relative 2000 m'. Depths sampled varied but never exceeded importance index in logarithmic scale, and is sub- 3.5 m.