Revista de Biología Tropical

Density, size and composition of howler monkeys, Alouatta palliata (Atelidae) and white-faced monkeys, Cebus imitator (Cebidae) in dry forest and reduced canopy areas, Costa Rica

2024-06-06T15:51:07-06:00

Introduction: The size, density, and composition of primate social groups are essential for understanding group dynamics and determining population management plans for primate conservation. Objective: To determine the size, density, and composition of howler monkeys (Alouatta palliata) and white-faced monkey (Cebus imitator) groups in dry forest environments and areas of reduced canopy in Palo Verde National Park, Costa Rica. Understanding how these species respond to different environments has important implications for conservation and reforestation efforts. Methods: Field sampling was carried out during February 2023 during the peak hours of primate activity (6:00-12:00 and 14:00-18:00). The individuals of both primate species were counted, recognizing the groups found in both types of environments (dry forest and reduced canopy areas). Results: Howler monkey group sizes were significantly larger in dry forests and at a higher percent of canopy cover. As for white-faced monkeys, a higher density was recorded in dry forests compared to the last census in 1987. Conclusion: Greater availability of resources (abundance of food and shelter sites) in closed environments favors the presence of a greater number of howler monkeys. Our analyses show that group size in this primate species depends on the type of environment. This study highlights the importance of long-term monitoring and studies of these parameters in wild primate groups.

Taxonomic richness, diversity, temporal variation, and ecological aspects of fish larvae in the Gulf of Tribugá, Colombia

2023-11-08T14:10:29-06:00

Introduction: The larval phase is critical in the fish life cycle, yet knowledge of its taxonomic identification, abundance, and temporal variation remains limited in tropical coastal environments. Objective: To identify fish larvae in the Gulf of Tribugá, Northern Pacific Colombia, and assess their temporal variability considering regional oceanographic variations. Methods: We studied fish larval assemblages during the cold and warm water periods of 2022.We collected larvae through daytime and oblique tows from 20 m depth to the surface using a 70 cm mouth cylindrical-conical net with 500 µm mesh. Results: We captured a total of 602 larvae of 89 species from 29 families, with Scombridae, Engraulidae, Nomeidae, Gerreidae, Carangidae, and Engraulidae being dominant. Key species included Auxis rochei (36.32 %), Anchoa spp. (11.77 %) and Cubiceps pauciradiatus (8.10 %) during the cold period, and Eugerres lineatus (27.04 %), Eucinostomus gracilis (5.43 %), and Sphoeroides sp.1 (4.12 %) during the warm period. Differences were found in larval assemblage structure and composition between the two periods, with a species turnover rate of 66 %. Conclusions: This study reports the presence of 89 fish species’ larval stages in the Gulf of Tribugá, with each oceanographic period presenting a distinct larval assemblage.

Structure of fish communities in relation to habitat in Matusagaratí Lagoon, Darién, Panama

2024-06-18T13:30:35-06:00

Introduction: Matusagaratí lagoon is an ecosystem with diverse habitats and environmental conditions that determine the diversity and distribution of aquatic life. Despite hydraulic connectivity, aquatic habitats generated by this diversity of environmental conditions could determine the composition and structure of fish assemblages. Objective: To understand the structure of fish community in three of these habitats. Methods: Multi-habitat sampling was conducted between March 2022 and September 2023, covering periods of drought and flooding, at 29 sites using different fishing techniques. Results: 1 913 fish from 50 species and 27 families were collected in approximately 320 km². Three fish assemblages were identified, each associated with a specific habitat. The river corridor of the Tuira River had the greatest diversity, followed by the tidal streams and lagoons. Conclusions: The analysis revealed notable differences between these habitats, with the river corridor dominated by peripheral species, while lagoons showed low diversity with generalized or hypoxia-adapted species. The presence of species such as Hoplosternum punctatum, Ageneiosus pardalis and Pimelodus punctatus in the wetland evidences the influence of the Choco region on Panama´s ichthyofauna. These findings could have important implications for the formulation of wetland conservation strategies.

Growth, recruitment and life history parameters of fish in Andean reservoirs

2024-04-16T12:49:48-06:00

Introduction: The formation of new anthromes such as reservoirs and dams to generate energy for human consumption, provides new environmental scenarios that condition the survival of the pre-existing fish species in the modified system.

Objective: To estimate some of the main population attributes in relation to growth and recruitment discussed in the context of the life histories of the species analyzed for a high-Andean river system.

Methods: Based on the historical sequence (2005-2017) for the seven species with the highest numerical record and frequency distributions, a typical population parameter estimation analysis was employed following the Growth Model proposed by von Bertalanffy (MCvB) and empirical equations to the respective complementary parameters.

Results: A total of 28 651 frequency lengths were analyzed, finding that those species with rapid growth and lower longevity prefer artificial lacustrine environments, species with opportunistic life history strategies (Astyanax microlepis and Roeboides dayi) and with a bimodal recruitment pattern, while species with intermediate growth were seasonal (Brycon henni y Hemibrycon caucanus), registered in tributaries to the reservoir, and in equilibrium (Andinoacara latifrons, Chaetostoma thomsoni and Coptodon rendalli) mainly associated with rivers, reservoirs, and streams or transitional environments to reservoirs.

Conclusion: The analysis of information on the population dynamics and live history of fish coexisting in a reservoir and its surrounding environments suggests a spatial segregation of fish species in response to a possible selection of their biological traits and other bioecological characteristics that sustain their local populations.

Demographic variations of the spotted snapper Lutjanus guttatus (Perciformes: Lutjanidae) along the Pacific coast of Costa Rica suggest the existence of two population units

2024-06-25T05:59:29-06:00

Introduction: The spotted rose snapper Lutjanus guttatus is one of the commercially most important fish species in tropical and subtropical areas of the Eastern Tropical Pacific. In Costa Rica, L. guttatus is one of the main target species of the artisanal fishery; traditionally, its management has considered a single population that extends along the entire coastal zone. However, there is no evidence that there is only one population unit, which could affect the effective management of this valuable resource.

Objective: Determine the population structure of L. guttatus caught on the Pacific coast of Costa Rica through demographic parameters.

Methods: A total of 428 specimens were analyzed, including 190 males and 238 females. The size structure, total length - weight relationship, maturity stages, mean size at sexual maturity, age and growth were estimated, differentiating between the northern, central, and southern Pacific of Costa Rica.

Results: Demographic variations were observed in size structure, total length-weight relationship, the average size of sexual maturity, and growth rates among the organisms caught in the three sampling regions.

Conclusion: The demographic variations of L. guttatus in the different capture areas suggest the probable existence of two separate population units; the first corresponds to the northern Pacific, and the second includes the central and southern Pacific areas. The above has important implications for the management of the resource.

High richness and spatio-temporal turnover of insects in urban environments: A case in a Latin American capital

2024-09-17T00:34:37-06:00

Introduction: Urban ecosystems are spaces in the city that provide ecosystem services and house a wide diversity of species. One of the key components that maintain different types of processes is insects. Objective: To characterize insect communities in four parks in a district of Lima by analyzing their composition and structure in two seasons of the year. Methods: For this evaluation, two samplings (winter and summer) were carried out using four traps (pitfall, canopy malaise, ground-level malaise, and night trap). Results: The results show a) a high richness with 191 registered morphospecies, grouped into 12 orders and 8 functional groups; b) a low similarity between parks (less than 40 % for the Jaccard index), which reveals a high spatial turnover; c) differences in community composition between winter and summer (temporal turnover), with greater richness and abundance of individuals in the warm season (139 morphospecies and 1 214 individuals, versus 105 morphospecies and 731 individuals for summer and winter respectively) and d) the variation of functional groups at both times of the year. Conclusion: The results show a high diversity and invite us to continue the study of insect diversity in urban ecosystems on a broader scale. Information Decision-makers must be considered this to implement measures that allow maintaining this richness of species in a framework where citizens can value and get benefits by the important role of these organisms in the city.

Flora of high mountain tropical peatlands: threats and management measures, Talamanca Range, Costa Rica

2024-08-19T15:26:19-06:00

Introduction: Tropical peatlands are highly fragile vegetal formations, especially vulnerable to anthropogenic impacts and changes in climatic conditions. Objective: To characterize the flora of the Talamanca peatlands, as well as identify their dynamics, threats, and impacts. Methods: The flora was analyzed in five peat bogs located in the Buenavista Massif, along the Inter-American Highway, at altitudes of 2 400 - 3 100 m, through field sampling. Subsequently, a Floristic Value Index (IVF) was designed to assess the state of conservation. Results: The floristic richness was determined in the peat bogs studied. A lower biological diversity was found in the three peatlands outside the state-protected natural spaces, suggesting the influence of the edge effect and agro-productive activities or their proximity to the Highway. In contrast, the Salsipuedes and Cerro Paramillo peatlands exhibited greater diversity, highlighting genera such as Blechnum, Puya, Chusquea, Myrsine and Vaccinium, in association with the bryophyte genus Sphagnum. A different floral composition was observed along the strip near the Inter-American Highway, characterized by species with lower water demand, especially genera such as Rubus and Pteridium, among others. Conclusion: From the identified floristic composition, the importance of peatlands as part of the mesoamerican hotspot ecosystems was determined, not only as repositories of biodiversity but also as sensitive indicators of human influence and environmental threats in the region associated with anthropic impact and climate change.

Epiphytic macrolichen as indicators of environmental changes in a montane forest of Panama

2023-08-11T10:22:48-06:00

Introduction: Corticolous lichens are organisms that respond to habitat modifications, which is why they are considered model organisms to evaluate environmental changes in different ecosystems. Objectives: To determine the species richness and community composition of corticolous macro lichens in montane forests and forest remnants. In addition, the effect of microclimatic factors in three areas with different degrees of light intensity and density of arboreous vegetation on the species distribution of recorded diversity was evaluated. Methods: The study was conducted in the Volcan Baru National Park, Panama. Three areas with different forest densities and host tree species, Comarostaphylis arbutoides and Quercus spp., were chosen, considering a total of 60 trees, 10 of each species in each area. The canopy's opening close to the host trees and its diameter at breast height were recorded. Linear models and multivariate analysis was used to determine changes in species richness and composition of epiphytic macro lichens. Results: The characteristics of the host trees (e.g. host species and area) conditioned the species richness, while the communities were limited by microclimatic changes (e.g. light) in different areas. Conclusion: The macro lichens communities analyzed responded to changes related to the host tree species and the microclimate, so they can be considered indicators of ecological continuity in tropical montane forests.

Comparative osteology of the caudal skeleton and vertebral column of the freshwater fish Tlaloc (Cyprinodontiformes: Profundulidae)

2024-09-17T12:44:26-06:00

Introduction: The family Profundulidae is a lineage of freshwater fish, with a limited geographical distribution extending from Southern Mexico to Central America, composed of two genera Profundulus and Tlaloc; the latter comprised only four species; however, studies based on the analysis of osteological characters are scarce for this family of fish. Objective: To describe the anatomy of the caudal bones and backbone of all species of the genera Tlaloc. Methods: A comparative analysis was performed on 44 cleared and stained specimens to identify the differences and similarities of backbone elements and the organization of the caudal skeleton among the species. Results: The comparison of the caudal skeleton in the species of the genus Tlaloc, revealed a very similar pattern in the morphology of the species; however, some characteristics were detected that may be useful for discrimination of species of the genus; the triangular shaped hipural plate is a characteristic that has only appeared in T. labialis, while in the rest of the species (T. candalarius, T. portillorum and T. hildebrandi), the hypural plate is fan-shaped. The total number of vertebrae, including the vertebral centrum, in the four species of the genus Tlaloc ranged from 33 to 38, of which 15-17 were abdominal vertebrae and 17-21 caudal vertebrae; T. portillorum had the lowest number of total vertebrae (33); while T. labialis had the highest number of total vertebrae (37-38) Conclusions: The consistent relationship to these skeletal elements suggests that the vertebrae and caudal fin ray count is a character of fundamental nature for the profundulid fishes, giving it particular taxonomic significance in that group.