Tidal, Diel and Seasonal Effects on Intertidal Mangrove Fish in a High-Rainfall Area of the Tropical Eastern Pacific
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Vol. 494: 249–265, 2013 MARINE ECOLOGY PROGRESS SERIES Published December 4 doi: 10.3354/meps10512 Mar Ecol Prog Ser Tidal, diel and seasonal effects on intertidal mangrove fish in a high-rainfall area of the Tropical Eastern Pacific G. A. Castellanos-Galindo1,2,3,*, U. Krumme1,2,4 1Leibniz Center for Tropical Marine Ecology (ZMT), Fahrenheitstrasse 6, 28359 Bremen, Germany 2Centre of Excellence in Marine Sciences (CEMarin), Cra. 2 No. 11-68, 47004 Santa Marta, Colombia 3Grupo de Investigación en Ecología de Estuarios y Manglares, Departmento de Biología, Universidad del Valle, A. A. 25360, Cali, Colombia 4Thünen Institute of Baltic Sea Fisheries (TI-OF), Alter Hafen Süd 2, 18069 Rostock, Germany ABSTRACT: Mangroves are recognized as nursery areas for a large number of marine organisms. Yet many properties of this nursery function and its equivalence between geographical areas remain poorly understood, especially in macrotidal estuarine systems. In this study, we investi- gated the influence of tides, diel and seasonal variation on intertidal mangrove fish assemblages in a high-rainfall area of the Tropical Eastern Pacific region. Over one year, block net sampling was undertaken during spring and neap tides during both night and day. Four sites along the length of a subtidal channel were sampled to account for salinity gradients. Clupeidae dominated catch abundances of a 50 species-rich assemblage. Catch weights, however, were dominated by Lutjanidae, Tetraodontidae and Ariidae. Fish biomass was low, likely as a result of a poor benthic in- and epi-faunal biomass in a mangrove system of low nutrient status and extremely rainy con- ditions. Higher salinity creeks yielded significantly greater catches and higher number of species than low salinity creeks. A depauperate freshwater fish fauna in this beogeographical region, unable to compensate for the lack of marine-estuarine species in a low salinity environment, may explain this pattern. A notable increase in rainfall at the end of the year correlated to a decrease in mangrove fish biomass. Partially in agreement with studies from other macrotidal areas, specific combinations of tidal magnitude and diel cycle explained recurring changes in fish assemblage structures, clearly observed at the species level, but not in the number of species or biomass. These results indicate not only how important tidal and diel cycles can be for fish habitat use in macrotidal mangroves, but also highlight how regional (biogeography) and local (geo- morphology, precipitation) factors should be incorporated into further investigations of mangrove ecosystem equivalence over large geo graphical scales. KEY WORDS: Intertidal mangrove creeks · Fish community · Block nets · Macrotides · Tropical Eastern Pacific · Panama Bight mangroves · Colombia · Bahía Málaga Resale or republication not permitted without written consent of the publisher INTRODUCTION against storm surge and increased fisheries yields in adjacent waters are some of the ecosystem and eco- Mangroves are among the most threatened eco - nomic benefits provided by mangroves (Alongi 2002, systems in the world, with an estimated rate of loss of Donato et al. 2011). Approx. 30% of the world’s com- 1 to 2% per year (Valiela et al. 2001, Polidoro et al. mercial fish species are considered mangrove- 2010). Carbon storage, sediment trapping, protection dependent (Naylor et al. 2000). Nevertheless, the *Email: [email protected] © Inter-Research 2013 · www.int-res.com 250 Mar Ecol Prog Ser 494: 249–265, 2013 role of mangroves as a fish habitat and nursery con- blages (and fish tidal migrations) are affected by tinues to be little understood (Beck et al. 2001) and salinity change and/or precipitation (but see Lorenz has proven to be variable across geographic areas & Serafy 2006, Giarrizzo & Krumme 2007, Rehage & (Sheaves 2005). Loftus 2007). Many of the studies highlighting the nursery func- Mangrove forests on the Pacific coast of the Amer- tion of mangroves thus far have been carried out in icas cover ca. 1.21 million ha (Lacerda et al. 2002). the Caribbean biogeographic realm where man- Important artisanal fisheries throughout the region grove forests are comparatively small, microtidal sys- depend either directly or indirectly on mangroves as tems (Krumme 2009, Nagelkerken 2009, but see they are considered essential habitats for the juve- Blaber 2000 for a review of studies in the Indo-Pacific niles of commercial species (Aburto-Oropeza et al. and African regions). However, mangroves else- 2008). The majority of these mangroves are located where may be subject to medium or large tidal in the Panama Bight ecoregion (covering the Pacific amplitudes and present a different habitat configura- coasts of Panama and Colombia and the coast of tion from the mangrove-seagrass-coral reef contin- Ecuador), 1 of 8 major mangrove areas identified as a uum most often described in the literature. In meso- global conservation priority (Olson & Dinerstein and macro-tidal regimes (range 2 to >6 m), fish 2002). Despite being relatively undisturbed, these accessibility to mangroves is limited to periods of mangroves are subject to environmental (i.e. ENSO intertidal inundation. Therefore, the dynamics of fish events) and human-driven (deforestation and pollu- assemblages and value of the mangrove as a nursery tion) stressors that pose serious threats to local habitat in these regions may be distinctly different human populations and could drive major changes in compared to those in microtidal systems. coastal food webs (Valiela et al. 2012, Restrepo 2012). Fish assemblages on macrotidal coasts exploit tem- This study examines, for the first time, the small porarily accessible habitats via tidal movements that and mid-term spatial and temporal patterns of man- are an important part of their home ranges (Gibson grove creek fish assemblage structure in a macroti- 2003). The importance of tidal movements for fish, dal mangrove area of the Tropical Eastern Pacific however, varies according to habitat. On the rocky Ocean (Colombian Pacific coast), filling a gap in the shores of the Colombian Pacific these movements are understanding of mangrove fish assemblage dynam- not related to spring-neap tide cycles (Castellanos- ics in this area (Faunce & Serafy 2006, Sheaves 2012, Galindo et al. 2010) whereas in the mangroves, com- Blaber in press). For this purpose, 3 questions were plex interactions in the organization of intertidal fish investigated: (1) What is the taxonomic and func- assemblages have been found following changes in tional composition of the intertidal mangrove fish spring, neap, diel and lunar cycles (Davis 1988, assemblage in a high-rainfall area of this region? (2) Krumme et al. 2004, Krumme 2009). These short to How does the variability introduced by changes in medium temporal scales are seldom considered in the tidal magnitude (spring-neap tide cycle) and its the study of fish community structure dynamics (Wil- interaction with the diel cycle affect the structure of son & Sheaves 2001), although crucial to understand- the intertidal mangrove fish assemblage? and (3) ing the dynamics of these assemblages. How does an extremely high precipitation-low salin- The influence of abiotic factors in shaping fish ity period affect the structure of this mangrove fish communities (salinity, turbidity) has been relatively assemblage? well studied in different ecosystems throughout the world (Blaber 1997). Although most estuarine fish species can be considered euryhaline, in estuarine MATERIALS AND METHODS mangrove systems a strong relationship between salinity and fish community composition has been Study area found (Sheaves 1998). Changes in salinity are ulti- mately a consequence of the precipitation regime, Bahía Málaga is located in the central region of the seasonality of the rainfall and size of the drainage Colombian Pacific coast (3° 56’ to 4°05’ N and 77° 19’ system at each study site. Most investigations exam- to 77° 21’ W) in the Tropical Eastern Pacific (TEP) ining the relationship between salinity and fish region (Fig. 1) and is an estuarine embayment (sensu assemblage structures have been carried out by sam- Pritchard 1967) formed during a tectonic event which pling in the main channels of estuaries (Barletta et al. occurred in the Miocene-Holocene Epoch. It is 2005, Simier et al. 2006). Only few studies have believed that the bay was a narrow channel of an old examined how intertidal mangrove creek fish assem- (Pleistocene) tributary system of the San Juan River Castellanos-Galindo & Krumme: Mangrove ichthyofauna in a high-rainfall macrotidal area 251 4°18’N N L1 76°55’ L2 W M2 8 M1 9 San Juan Delta Luisico 01000 m B Bahía Málaga 10 m 10 m 20 m 20 m 30 m 20 m 20 m 10 m 20 m N 10 m Caribbean Sea 10 m Tropical Eastern Colombia 77°37’ Pacific Bahía de 0 10 20 W km Buena ventura A 3°46’N 0 0 1 1 2 2 3 Depth (m) 3 0481216 0 246810 L1 Width (m) L2 Width (m) N N 0 50 m C 0 50 m D 0 0 1 1 2 2 M1 Depth (m)3 Depth (m) Depth (m) 3 02 4 6 8 10 041012 Width (m) Width (m) N N M2 0 50 m E 0 50 m F Elevation (m) 0–0.30.3–0.6 0.6–0.9 0.9–1.2 1.2–1.5 1.5–1.8 1.8–2.1 2.1–2.4 2.4–2.7 MHWS Fig. 1. (A) Coast of the Tropical Eastern Pacific region, and (B) location of the 4 intertidal mangrove creeks in the Luisico tribu- tary of Bahía Málaga. Bathymetric maps of (C,D) the 2 low-salinity creeks (L1 and L2) and (E,F) the 2 medium salinity creeks (M1 and M2). Subfigures in C–F show a cross-sectional profile from the creek entrance, sampled from December 2009 to November 2010. MHWS = mean high water at spring tide 252 Mar Ecol Prog Ser 494: 249–265, 2013 (one of the largest deltas along the west coast of torically very low; currently it is between 5 and 17 South America) that was flooded after a tectonic persons km−2 (Etter et al.