INTROPICA

21-34

Authors: Adriana Pedroza-Ramos, Pedro Caraballo and Nelson Aranguren-Riaño

A fundamental and effective way to view the dynamic patterns and properties of a community is through the trophic network, understood as a map of the interrelationships between the structure of an ecological community and the processes that occur within the ecosystem. In this study, we describe an aquatic food web composed by aquatic invertebrates, detritus and periphyton associated with the plant Egeria densa. Samples were collected during the transitional and rainy season at four stations in the littoral zone of Tota Lake. Three samples (300 g each) of plant material at every point were randomly collected. Electrical conductivity, pH, dissolved oxygen and temperature were measured in situ. The eating habits were assigned by means of bibliographic information and in some cases observation. Finally, we developed a static type model that included 112866 individuals distributed among 26 taxon, which were classified according to their eating habits in: two top trophic species, 16 intermediate and two basal species. We found that this trophic network represents a connectance of 0.13 and density links of 2.95. The model also revealed that E. densa is a basal trophic species. Together, these results demonstrate that E. densa is an important generator of detritus and periphyton substrate, supporting other trophic levels in the community. Moreover, the presence of ten trophic species of primary consumers generates high ecological redundancy that at the same time guarantees the flow of resources toward higher trophic levels.

47-56

Authors: Néstor Ned Torres-Zambrano and David Rolando Torres-Zambrano

Composition and some functional implications in aquatic macroinvertebrates at the head creek Los Alisos placed in west of Firavitoba town -Boyacá department is presented. During August and September 2016, we taken two samples. Functional feeding groups and biological traits from bibliographic information were determinate, finding 7 feeding mechanisms and 19 biological traits. 2688 individuals were recollected of which are 3 phylum, 6 class, 11 orders, 21 families and 14 genera where the highest relative abundance are Hyalella genus (Amphipoda) (20.3 %). The trophic group detritivores-collectors or deposit consumers (C2) is the most common in the system (68.2 %), which suggests that dominate by fine particulate organic material (FPOM). The gill respiration is the most frequent because it occurs in 12 of the 22 taxonomic groups with 54.5 %. Tarsal hooks (GA) have the most organisms (54.5 %) that can be eventually used counter flow strength. Almost all organisms studied walk or crawl (AR, 68.2 %) using a variety of habitats as substrates. The life stories flexibility and mobility that show the characteristics of taxonomic groups found in the Los Alisos creek can influence how they get their food.

67-72

Authors: Limarie J. Reyes-Torres, Yazminne Meléndez-Torres and Alonso Ramírez

Nematodes are common symbionts of aquatic insects. Here, we assessed the presence of nematodes in mayfly nymphs (Ephemeroptera), evaluated their prevalence in the population, and determined factors associated with nematode presence. Mayflies were collected (n = 130) from three stream habitats (riffles, pools, and boulders) using a D net, in Prieta stream, El Verde Field Station, Puerto Rico. Mayflies were dissected and nematode presence was determined under a light microscope (4 x and 10 x). Nematode prevalence was 50 %. Nematodes were not identified beyond Phylum level, but we were able to eliminate various groups as infective agents (Nematoda: Mermithidae and Nematomorpha: Gordiida). They were mostly found in the abdomen, head or thorax of mayflies. There were differences in infection among taxa, Neohagenulus was the group with the highest proportion of infection. Mayfly body shape, feeding strategy, or activity potentially explain differences in infection among taxa. There were no differences in infection among habitats, but mayflies were less abundant in riffles; and there was no relation between mayfly body length and the number of nematodes present. To our knowledge, this is the first report of a nematode present in mayfly nymphs in Puerto Rico.

85-95

Authors: Marcela González-Córdoba, María del Carmen Zúñiga, Zuleyma Mosquera-Murillo and Sandra Sánchez-Vásquez

The Elmidae are water beetles, common and widely used as bioindicators of water quality for their sensitivity to organic pollution. To contribute to the knowledge of the family in the department of Chocó, a region which the taxonomic, ecological and distributional studies for this family are incipient, specimens deposited mainly in the Colección Limnológica del Chocó (Universidad Tecnológica del Chocó) and the Museo de Entomología de la Universidad del Valle, were analyzed. 958 specimens (adults and larvae), collected in 14 municipalities between 5 and 2063 meters, 40 streams of different orders, and two lentic ecosystems that drain mainly into the Atrato and San Juan rivers were analyzed. 17 genera (12 of the subfamily Elminae and five of the Larainae) and four species are recorded in this study. Austrolimnius, Hexacylloepus, Hexanchorus, Huleechius, Microcylloepus, Neocylloepus, Neoelmis, Onychelmis, Stenhelmoides, Pharceonus, Pseudodisersus and Xenelmis, are new records to Chocó and Cylloepus, Disersus, Heterelmis, Macrelmis and Phanocerus, Cylloepus, Macrelmis and Heterelmis, already known, increase their range of distribution in the region. Two species are new records for Colombia (Austrolimnius pusio y A. formosus) and two for the Chocó (Stenhelmoides rufulus and Pseudodisersus goudotti). Those records represent 70.8 % of the Elmidae generic richness known for Colombia. Most taxonomic records were found in the middle basin of the Atrato River between 25 and 150 meters. The Andean region and the upper basins of the Atrato and San Juan and the entire Baudó rivers exhibited the biggest lack information. Macrelmis, Cylloepus, Microcylloepus, Phanocerus, Neoelmis and Heterelmis, had the widest distribution, while Disersus, Hexacylloepus, Onychelmis and Pharceonus, were restricted to a single locality in low areas. Based on this work the Chocó, together with the Valle del Cauca, Antioquia and Meta, has the most generic richness of the family among the departments of Colombia.

105-110

Authors: Juan Carlos Valdelamar-Villegas

Feeding management in artificial ponds is one of the most important aspects in shrimp culture, as this may represent about 40 % of the operating costs, because of that several authors have focused their research on optimizing this aspect. This work was aimed to present the appropriate logistic regression model to predict the behavior of the dichotomics variable shrimp feeding state (over-fed = 1 and not over-fed = 0), from independent variables (qualitative dichotomic: intestine content benthos or emptied (CIBV = 1), intestine contents with food (CIA = 0) and the quantitative variable weekly growth (CS). Results show that the logistic model is the one that best explains the behavior of data, in additionvariable, weekly growth and intestine content of benthos or emptied, turn out to be the most significance. Results found in this work are discussed.

127-135

Authors: Luis Alberto De La Hoz-Barrientos and Farid Jesús Osorio-Ávila RESUMEN El

The phycoperiphyton plays a fundamental role in the dynamic of wetlands due to the fact that possess important attributes as bio-indicators and because of its sensitivity to environmental changes. The aim of this paper is to determine the composition and structure of phycoperiphyton assemblage related to macrophytes’ roots at a tropical swamp in the northwest of Colombian. Three samples were taken (June 2015, September 2015 and January 2016) in three separate locations in the eastern area of the swamp. In each location a sample of 5 cm2 was taken from the roots of three individuals for each dominant macrophyte. Simultaneously, in situ water chemical and physical variables were measured (pH, conductivity, oxygen, temperature, depth, light extinction, sedimentary solids and radiation). Reports of 81 morphospecies were found, being diatoms and chlorophytes the dominant algae. The macrophyte Eichornia crassipes were the richest substratum with the highest algae density. Cymbella, Gomphonema, Monoraphidium y Cosmarium were considered as successful colonizers, as they were found in the majority of the substratum evaluated. Due to its high nutrient recycling rate, periphytic algae plays a fundamental role in the dynamics of this swamp.