Habitat characteristics and environmental parameters influencing fish assemblages of karstic pools in southern Mexico

Abstract

Fish assemblage structure was evaluated and compared among 36 karstic pools located within protected areas of the Calakmul Biosphere Reserve (southern Mexico) and unprotected adjacent areas beyond the Reserve. Nonmetric multidimensional scaling (MDS), indicator species analysis (ISA), and canonical correspondence analysis (CCA) were used to identify which environmental factors reflected local influences and to evaluate the correlation of these variables with fish assemblages structure. Thirty-one species were encountered in these karstic pools, some for the first time within the Reserve. These aquatic environments were separated into three groups based on physico-chemical characteristics. Although CCA identified significant associations between several fish species (based on their relative abundance) and environmental variables (K, NH4, NO3, and conductivity), the most abundant species (Astyanax aeneus, Poecilia mexicana, and Gambusia sexradiata) occur in most pools and under several environmental conditions. Baseline data on fish diversity along with a continued monitoring program are essential in order to evaluate the conservation status of fish assemblages and their habitats, as well as to measure the influence of anthropogenic impacts on pristine habitats such as the karstic pools of the Calakmul Biosphere Reserve.A estrutura da assembleia de peixes foi avaliada e comparada entre 36 poços cársticos localizados dentro de áreas protegidas da Reserva da Biosfera Calakmul (sul do México) e nas áreas desprotegidas adjacentes à Reserva. A análise multidimensional não-métrica (MDS), a análise da espécies indicadora (ISA) e a análise de correspondência canônica (CCA) foram utilizadas para identificar as variáveis ambientais localmente mais importantes e para avaliar a correlação destas com a estrutura das assembleias de peixes. Trinta e uma espécies foram amostradas nos poços cársticos, algumas das quais representam o primeiro registro para a Reserva. Os poços foram separados em três grupos de acordo com as suas características físico-químicas. Embora a CCA tenha possibilitado a identificação de associações significativas entre várias espécies (baseado na abundância relativa das espécies) e as variáveis ambientais (K, NH4, NO3 e condutividade), as espécies mais abundantes (Astyanax aeneus, Poecilia mexicana e Gambusia sexradiata) ocorreram na maioria dos poços em diferentes condições ambientais. A obtenção de dados de base sobre padrões de diversidade, associado a implantação de programas de monitoramento, são essenciais para a avaliação do estado de conservação das assembleias de peixes e seus habitats, assim como para proporcionar informações sobre a influência de impactos antropogênicos sobre habitats prístinos, tais como os poços cársticos da Reserva da Biosfera Calakmul.

Phylogenetic analyses of the subgenus Mollienesia (Poecilia, Poeciliidae, Teleostei) reveal taxonomic inconsistencies, cryptic biodiversity, and spatio-temporal aspects of diversification in Middle America

“…Nonetheless, the presence of widespread species in both species complexes clearly indicates a high potential for dispersal even across major phylogeographic barriers. For example, both P. sphenops and P. mexicana occur on both the Atlantic and Pacific slopes, and their ability for dispersal and colonization of novel habitats may be mediated by high tolerance to environmental stress (see Hernández-Rodríguez and Bückle-Ramirez, 2010;Tobler et al 2009;Trexler, 1986;Vega-Cendejas et al, 2013).…”

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“…From these rivers, maximum level of fish abundance was detected at low water temperature and small flowing discharge in winter but minimum fish diversity viewed with comparatively high temperature and water discharge in summer differed by Yan et al (2010) due to geographical variation. Alteration in water quality parameters such as water temperature, dissolved oxygen, pH, transparency and depth influence the uniqueness of aquatic environment and fish breeding (Kathiresan and Bingham, 2001;Rashleigh, 2004), profusion and allotment (Maes et al, 2004), migration and distribution (Vega-Cendejas et al, 2013) and survival of fishes (Whitfield, 1999) ultimately altering fish assemblage and structure. However, significant differences (P < 0.05) were observed in hydrological parameters among habitat and season similar to Grimaldo et al (2012).…”

Distribution, Spread, and Habitat Predictability of a Small, Invasive, Piscivorous Fish in an Important Estuarine Fish Nursery

“…In freshwater habitat of south Florida's Everglades National Park, Kerfoot et al [37] found a positive relationship between pH (range:~7.4-8.0) and B. belizanus density at one site, a weak positive relationship at another site (pH range:~7.2-7.4), and negative relationships at two other sites (pH ranges:~7.3-7.6 and~7.6-8.1). Multispecies ordination analyses within the native range do not demonstrate strong or consistent relationships between pH and B. belizanus populations [33][34][35][36]. As noted by Kerfoot et al [37], changes in pH are known to directly affect ion uptake across gills and internal acid-base balance in fishes, ultimately affecting survival rates.…”