Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

Introduction: The red swamp crayfish, Procambarus clarkii, is a crustacean species native to Mexico and the United States. It has been introduced around the world, often becoming established as an invasive exotic species. Since its introduction in 1985 in Colombia, no studies have been carried out to determine factors that influence the presence of the species in high mountain ecosystems. Objective: To evaluate the relationship over time between macrophytes and the different stages of development of P. clarkii in a tropical high Andean aquatic ecosystem. Methods: A new collection method called "macrophyte sweep" was standardized. This method ensured the collection of crayfish of all possible sizes, especially juveniles. Sampling was carried out bimonthly for seven months. The morphometry of P. clarkii was evaluated in three macrophytes: Juncus effusus, Ludwigia peruviana, and Polygonum punctatum. Results: A total of 778 individuals were collected, of which 365 were females, 344 males, and 69 sexually indeterminate. The total population density was 6.48 ind/m2. Most organisms were found on P. punctatum (71.9 %), followed by L. peruviana (17.7 %) and J. effusus (10.28 %). The largest and heaviest organisms were recorded in September in all three macrophytes, while the smallest were collected in July and May. P. clarkii exhibited a greater affinity for the macrophyte P. punctatum in its different developmental stages, possibly because it offers greater structural complexity in the submerged zone, providing shelter for juveniles and a food source for adults. Conclusions: Our results highlight that much of the colonization success of P. clarkii is due to the relationship between macrophytes and the development of different life stages in neotropical ecosystems.

Introduction: Procambarus clarkii is an invasive species introduced to central Mexico that threatens biodiversity. Objective: To analyze monthly, during an annual cycle, the demographic and morphometric changes of P. clarkii concerning environmental variation in a reservoir (Taxhimay, State of Mexico). Methods: Abundance, sex ratio, fecundity, and nutrition in females were determined using the hepatopancreatic (HSI) and gonadosomatic (GSI) indices. Results: The PCA showed that phycocyanin, chlorophyll a, and pH explained 80.7 % of the environmental variation and grouped the sample sites into October-February, March-April, May-July, and August-September. A total of 464 individuals were captured; 198 (43 %) were females, and 266 (57 %) were males, of which 26 were non-reproductive form II. Abundance was positively correlated with phycocyanin and chlorophyll a and negatively correlated with transparency and depth. The highest abundance of organisms occurred in April at the end of the dry season. According to HSI and GSI, two reproductive seasons were recorded in June-September and January-March. Morphometric variables statistically different between males and females were cephalothorax width, length and width of chelae, and dactylus. In addition, it was recorded that the average length of P. clarkii in the Taxhimay reservoir is larger than that reported in its natural distribution area and other places where it has been introduced into Mexican territory and Europe. Conclusion: The environmental conditions of the Taxhimay reservoir are conducive to the establishment and growth of P. clarkii, thereby endangering native species in central Mexico.

Introduction: Tukakas Bay, located on the border between Colombia and Venezuela, is practically unknown in terms of its marine biodiversity. This lack of knowledge generated the need to carry out an expedition to evaluate the current state of its associated biodiversity. Objective: To describe for the first time fish biodiversity in Tukakas Bay through integrated sampling methodologies. Methods: We combined environmental DNA (eDNA) from seawater with observations and morphological methods, and subsequent mitochondrial DNA barcoding (COI, 16S) to describe fish biodiversity. Water samples for eDNA analysis were concentrated in four transects along the bay and processed in laboratory. Visual censuses were carried out through scuba diving and snorkelling, and fish were collected in 17 stations. Tissue samples were subtracted and preserved for DNA barcoding. Voucher specimens were fixed and preserved for taxonomy. Both specimens and tissue samples are part of reference collections at MHNMC, and their metadata are available in the public domain. Results: We identified 481 ASVs belonging to 95 species, 68 genera, and 52 families from eDNA, visual censuses, and morphology (including DNA barcoding). Detections made with eDNA included solitary species and represented 65 % of all identified fish taxa in Tukakas Bay, from which 15 species were also observed or collected. Specimen collections were effective for the creation of 45 DNA barcodes and 164 DNA sequences, and the confirmation of taxonomic assignations obtained by the other two methods. We improved taxonomic resolution for 20 % of the taxa by combining these three survey methods. Conclusion: Integrating eDNA metabarcoding approaches to traditional fish surveys significantly improves biodiversity assessments specially on remote areas.

Introduction: Freshwater ecosystems are some of the most threatened globally, including their ichthyofauna. To understand the factors that affect species composition and distribution of fish communities in rivers, it is important to include different assessment scales. Gradients of natural and anthropic origin converge in the Garagoa River, an ideal condition for the study of impact of multi-scale variables on freshwater ichthyofauna. Objective: evaluate the influence of variables at a local and landscape scale on the fish communities of the Garagoa River basin, through the analysis of beta diversity partitioned into the turnover and nesting components. Methods: Sampling was carried out in 36 transects of 100 m, between February and July 2021. The collection was carried out using electrofishing and trawl nets and physical, chemical and morphological characteristics of the section (local variables) were recorded. Using secondary information, information on land use, geomorphological and bioclimatic characteristics (landscape variables) was obtained. Beta diversity was calculated and the influence of local and landscape variables on this component was analyzed, using Principal Component Analysis PCA and Distance-Based Redundancy Analysis dbRDA. Results: We recorded 22 species from 10 families and five orders. The dissimilarity in species composition was high (93 %), 81 % explained by species turnover. These components were related to local variables, land use, geomorphological and bioclimatic characteristics. Conclusions: The species composition in the Garagoa River basin is distributed according to the elevation gradient and is affected by a set of variables at the local and landscape scale that include natural characteristics and conditions generated by human activities. The most relevant are the physicochemical characteristics of the water, the morphology of the channel, the quality of the riverside vegetation, the characteristics of the relief, as well as the distribution of areas with natural cover and areas affected by agricultural, livestock, mining or urban processes.

Introduction: Humanity faces a multidimensional crisis with severe threats to often poorly known freshwater biodiversity. Molecular tools, like DNA barcoding, can aid in biodiversity exploration, monitoring, and conservation. Sulawesian Caridina shrimps are both ecologically significant and endangered yet remain understudied. Objective: To contribute well-documented DNA barcode (COX1 mtDNA) sequences for three Caridina species endemic to Lindu Lake. Methods: We collected 224 Caridina shrimps from three sites around Lindu Lake in August (n = 73), and October 2023 (n = 117), and July 2024 (n = 34). We measured and analyzed morphological traits as dimensionless ratios of total length. We extracted DNA from six specimens (two per species) and COX1 mtDNA barcodes obtained through PCR (primers jgLCO and jgHCO) and Sanger sequencing. We obtained homologous sequences from GenBank (BLAST routine) and BOLD repositories for phylogenetic analyses. All molecular analyses were performed in MEGA 11. Results: One species was identified at each site. Morphological traits differ between species. Three haplotypes with low divergence: one in Caridina kaili, one in Caridina linduensis, and one in both Caridina dali and C. linduensis. Homologous sequences in GenBank and BOLD included very few Sulawesi endemic species; these formed the closest sister clades to Lindu Lake Caridina. Conclusions: We submitted to the GenBank repository the first reference DNA barcodes for each of the Lindu Lake Caridina species. The poor resolution of COX1 mtDNA for Lindu Lake Caridina may be due to recent evolutionary processes. Our study highlights the ongoing need for barcoding freshwater invertebrates, particularly atyid shrimps from Sulawesi, in the Wallacea bioregion.

Introduction: Although many reefs have been disturbed by the combined effects of climatic and non-climatic stressors, there still are regions largely free from direct human pressures such as runoff, pollution, and maritime traffic due to their geographic remoteness. This suggests that they are replicas of “pristine reefs”, that allow the investigation of relationships between reef communities and their environment. Objective: To evaluate the status of the coral formations of Bajo Nuevo, Seaflower Biosphere Reserve. Methods: The coral health and the relative cover of reef-building organisms and of their main competitors were evaluated. In every station (11), ten photo quadrants of 0.25 m2 were evaluated along a 10 m tape measure combined, along with ~3 min videos. Results: 32 coral species were recorded, 30 of them Scleractinia and two of hydrocorals, with the highest richness in the reef lagoon. In 2021, the reefs in Bajo Nuevo were dominated by non-reef-building organisms (61.7 ± 0.10 %), the building species represented only 23.9 ± 0.10 %; 3.2 ± 0.03 % was coral skeleton with recent and transitional death less than 15 days old. Signs of diseases affected three genera, 13 species and 23.5 % of the colonies evaluated, of which 84.9 % showed one of the four signs related to the stony coral tissue loss disease. Conclusions: With previous expeditions (2010-2011) as a reference, this reef complex registered in 2021 a drop in the cover of hard corals and calcareous algae, and coral richness; an increase in the cover of non-reef-building organisms, with a high prevalence of signs of unhealthiness associated with different coral diseases. This confirms that these reefs are in danger (EN), as suggested by the red list of marine and coastal ecosystems of Colombia.

Introduction: Sea urchins of the genus Echinometra are ecosystem engineers that burrow into lower intertidal and subtidal rocks, creating shelter for themselves and a variety of marine animals. Objective: To test the hypothesis that motile macroinvertebrates and fishes shelter proportionately more frequently in burrows with Echinometra mathaei, whose spines potentially offer additional protection, than in burrows without E. mathaei. Methods: We studied the motile macroinvertebrates and fishes sheltering in the burrows of the Indo-Pacific Rock-boring Urchin E. mathaei (Type C) at Mana Island, Fiji. Results: Burrows with E. mathaei averaged shorter in length than burrows without E. mathaei. We observed 42 motile macroinvertebrates of at least eight species and 49 fishes of at least eight species in burrows with E. mathaei (n = 1 127), and four motile macroinvertebrates of three species and one fish of one species in burrows lacking E. mathaei (n = 243). Motile macroinvertebrates occurred with statistically equal frequencies in burrows with E. mathaei (3.6 %) and in burrows without E. mathaei (2.5 %). Fishes occurred significantly more frequently in burrows with E. mathaei (4.3 %) than in burrows without E. mathaei (0.4 %). Conclusion: Fishes, but not motile macroinvertebrates, gain more protection from predators by sheltering in burrows with sea urchins, whose spines offer additional protection, than in burrows without sea urchins.

Introduction: Sludge Biotic Index (SBI) is one of the most used indices for the characterization of the community of microorganisms present in the activated sludge of wastewater treatment systems. However, this index takes into consideration only the density of the predominant functional groups of protozoa that inhabit this sludge. Objective: To evaluate whether the SBI value can be directly related to the number of protozoos and metazoos species found in the activated sludge of two wastewater treatment systems. Methods: This study was carried out on the wastewater generated by the San Vicente de Paul Hospital in Heredia Province, Costa Rica, during the months of February, March, and April 2022. Physicochemical, environmental, operational, and biological parameters were analyzed in a total of 36 samples from a Conventional activated sludge wastewater treatment system and from a Membrane Bioreactor (MBR) (n = 18 for each treatment system). Results: All the parameters evaluated are related to the abundance of microorganisms in the samples analyzed. The SBI value had an important effect on the number of organisms and can be related to the performance of the treatment system in terms of the percentage of Biochemical Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) removal, especially for the MBR system. Conclusions: The SBI can be improved so its calculation not only considers functional groups but also includes genus and species of protozoos and metazoos present in the activated sludge. Which in turn would refine its bioindication potential by being more specific in terms of abundance, behavior and specific requirements of each species.

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.

Introduction: The Bocachico Prochilodus magdalenae, an endemic herbivorous/detritivorous fish from the Magdalena River basin, is the region’s most important fishing resource, with high ecological and socioeconomic significance. Its populations have declined significantly due to fishing pressure and anthropogenic environmental stressors, including wastewater discharge, infrastructure projects, and material extraction. Understanding the characteristics of its digestive tract is a crucial knowledge gap, hindering the comprehension of nutritional and physiological processes vital for aquaculture and both in situ and ex situ conservation efforts. Objective: To characterize the morphological, histological, and histochemical features of P. magdalenae’s gastrointestinal tract (GIT) and relate them to its feeding habits. Methods: Fifteen adult specimens from the Sogamoso River (Santander, Colombia) were analyzed using standard morphological measurements and histological and histochemical staining techniques for tissue structure and mucin distribution analysis. Descriptive statistics were used for morphological analysis. Results: Specimens averaged 24.66 cm standard length, 291.77 g weight, and 1.02 condition factor, with a mean GIT weight of 12.02 g. The digestive tract showed four distinct regions: oropharyngeal cavity, esophagus (mean length 1.26 cm), stomach, and intestine (mean length 88.18 cm). The esophagus contained abundant acinar glands, producing neutral and acidic mucins, with acidic mucins predominating. The U-shaped stomach showed simple columnar epithelium with tubular gastric glands producing only neutral mucins. The intestine, lined with simple columnar epithelium, exhibited differential mucin distribution: high neutral mucins anteriorly and predominantly acidic mucins in middle and posterior segments. Conclusions: The gastrointestinal characteristics align with its feeding habits, particularly the elongated intestine and thick pyloric muscular layer. The distinct mucin distribution pattern, especially the carboxylated acidic mucins in the middle and posterior intestinal segments, supports nutrient absorption functions. These findings provide crucial reference points for fish welfare assessment, pathogen response in aquaculture, and environmental impact evaluation in natural habitats.