Altitudinal variation in fish assemblage diversity in streams of the central Andes of Colombia

to determine the population status of Centrolene savagei (Centrolenidae) in the Western and Central Andes of Colombia. Scope: promotion of the population study of the endemic glassfrogs species of Colombia. Methodology: C. savagei (Centrolenidae) has only been registered in the Central and Western Andes of Colombia. We conducted a visual encounter survey in eight different localities where C. savagei was previously reported: Alto Bonito, Florencia, La Pastora, Santa Rosa de Cabal, Filandia, Boquía, Alto el Otoño and Chicoral, with an effective sampling effort of 54 h per locality. Each captured individual was marked, sexed and the height above water level of the perch was registered. Furthermore, all detected clutches in each survey were also marked and height above water level was recorded. We use a standard capture-recapture model to estimate the size of the population in each study site assuming closed population conditions. Main Results: C. savagei was absent at La Pastora and Florencia. In all localities where C. savagei was registered, male individuals and clutches were usually found between 1.5-2.0 m, while female individuals remain most of the time above 6 m height, and only go down for reproduction. The population size of C. savagei in the study area of Alto del Otoño was 132 ± 13 ind, in Chicoral was 41 ± 8 ind and in Santa Rosa de Cabal was 37 ± 6 ind. In Filandia, Boquia and Alto Bonito, recaptures were not carried out, so the size of the population could not be estimated. Conclusions: The presence of C. savagei in 75% of the localities where it had previously been reported suggests that the biotic and abiotic conditions in these sites are still adequate to sustain populations of this endemic species.

We recorded the species composition of mixed bird flocks, during 366 h of fieldwork in seven localities along an altitudinal gradient on the Central Andes of Colombia. We observed 164 species in 212 mixed bird flocks. Species composition varied along the altitudinal gradient and 27 species could have a cohesive role in the flock, but almost all of them were different among localities. The number of species per mixed flock varied from two to 30. The mean number of species per flock also varied among localities, and the differences among the whole set of species joining mixed flocks in each locality seem to be related with both differences in altitude and geographic distance.

Background Tidal cycle is an important factor which regularly changes coastal fish assemblages in shallow waters. However, the variations in fish assemblage and trophic structure across tidal cycles in tropical seagrass beds are rarely discussed. We used underwater visual censuses to quantify fish abundance and diversity from the shallow intertidal to the subtidal zone during both flood and ebb tides in seagrass beds surrounding the Dongsha Island, South China Sea. We also recorded fish feeding habits by analyzing stomach contents. Results At least 70 fish species were observed in the seagrass beds during the study periods. Fish density and diversity increased with increasing depths, as well as during flood tides. The intertidal areas were characterized by more variation in both fish assemblage and trophic structure than the subtidal areas. A cluster analysis identified six principal feeding groups and invertebrate-feeding carnivores contributed about 70% of the total fish abundance. The density of herbivores, large-sized carnivores, and piscivores, but not small-sized carnivores, increased during flood tides. In contrast, detritivores decreased in density during flood tides. A heatmap of habitat usage pattern revealed that most fish showed a preference for deeper stations and flood tides. Only a minority of fish showed a preference for shallower stations and ebb tides. Conclusions We documented differences in fish assemblage and trophic structure between tides in tropical seagrass beds. Our results suggest that water depth may account for a significant proportion of the variation. The deeper water during flood tides support more space for herbivores and high trophic level carnivores to forage in intertidal meadows. The remaining, non-ebbed seawater columns in the intertidal meadows formed important temporary refuges for fishes during ebb tides. This study offers new information for fish movements over tidal cycles in tropical seagrass beds.

The Colombian Andean Mountains include the headwaters of the main basins of the country. However, the isotope composition of water in these high mountain ecosystems has been poorly studied. In this study, we analysed the first set of stable isotope data collected along a wide elevation range (2600–4950 m a.s.l.) in the Central Andes of Colombia. The stable isotope composition of stream water and precipitation was determined for a period between 2017 and 2018 in the Upper Claro River basin. The driving factors influencing the spatial and temporal variability of δ2H, δ18O, and d‐excess were identified, and compared with daily air temperature and precipitation data from seven meteorological stations. The local regression line was described by δ2H = 8.2 δ18O + 12.3, R2 = 0.98. The δ2H and δ18O values showed more depletion in heavy isotopes, and the d‐excess values were more negative during the rainy season. An altitude effect of −0.11‰/100 m and −0.18‰/100 m was estimated for stream water and precipitation δ18O values, respectively, with the latter showing non‐linear behaviour. The dataset was compared with Colombian stations of the Global Network of Isotopes in Precipitation database, and a back‐trajectory analysis of air masses was conducted and compared with the d‐excess values. The δ18O weighted mean values changed with respect to the position in the Central Andes, indicating contrasting altitude effects depending on the moisture sources. The most positive d‐excess values were attributed to moisture recycling enhanced by local ecosystem conditions and the origin of precipitation from the Amazon basin, which change during the year and across the northern Andes. The results showed a high level of variation because of differences in elevation, seasonality, and atmospheric circulation patterns during the year. This study contributes to knowledge of spatial and temporal isotope composition data in the northern Andes, delineation of water supply basins, and to the definition of ecosystem boundaries in the high mountains of Colombia.

Borrow‐pit lakes encompass about a third of the lentic water habitats (by area) in the active floodplain of the Lower Mississippi River, yet little is known about their fish assemblages. We investigated whether fish assemblages supported by borrow‐pit lakes resembled those in oxbow lakes to help place the ecological relevance of borrow‐pit lakes in context with that of natural floodplain lakes. In all, we collected 75 fish species, including 65 species in eight borrow‐pit lakes, 52 species in four riverside oxbow lakes, and 44 species in eight landside oxbow lakes. Significant differences in several species richness metrics were evident between borrow‐pit lakes and landside oxbow lakes but not between borrow‐pit lakes and riverside oxbow lakes. All three lake types differed in fish assemblage composition. Borrow‐pit lakes and riverside oxbow lakes tended to include a greater representation of fish species that require access to diverse environments, including lentic, lotic, and palustrine habitats; fish assemblages in landside oxbow lakes included a higher representation of lacustrine species. None of the fish species collected in borrow‐pit lakes was federally listed as threatened or endangered, but several were listed as species of special concern by state governments in the region, suggesting that borrow‐pit lakes provide habitat for sensitive riverine and wetland fish species. Differences in fish assemblages among borrow‐pit lakes were linked to engineered morphologic features, suggesting that diversity in engineering can contribute to diversity in fish assemblages; however, more research is needed to match engineering designs with fish assemblage structures that best meet conservation needs.

Differences in fish assemblages’ composition and their relationship with the environmental variables were analyzed in the Urías estuarine system, Mexican North Pacific. Environmental variables and fish catches were recorded bimonthly between June 2018 and November 2021, including a period before and during the COVID-19 pandemic. Multivariate analyses were performed in the studied area to define zones based on their environmental, biotic, and abiotic characteristics and the effect of these on the fish assemblages. Two zones were identified, an estuarine with mangrove forest and a surf zone in the coastal area outside the estuarine system. Fish composition, biomass, and diversity (α and β) were evaluated among the factors of the period (before–during COVID-19), climatic seasons, and zones. A total of 5947 fish individuals of 41 species were collected using beach seines as fishing gear. The structure of the fish assemblages was different between zones and periods. Abiotic (temperature, salinity, and total matter suspended), biotic (mangrove area), and temporal (season and period before–during COVID-19) variables had an effect on fish biomass and α diversity, while the results of the β diversity only indicate changes in the nestedness component before–during the lockdown. These results indicate a change in fish assemblages’ structure and composition between periods, which might be a consequence of the limitation of human activities derived from the pandemic, climatic changes, or a combination of both effects. Our results show that fish assemblages in the estuarine systems of the Tropical Eastern Pacific are unique, and there is a need to establish local management strategies for these ecosystems.

Understanding the drivers of variability in the composition of fish assemblages across the Indo-Pacific region is crucial to support coral reef ecosystem resilience. Whilst numerous relationships and feedback mechanisms between the functional roles of coral reef fishes and reef benthic composition have been investigated, certain key groups, such as the herbivores, are widely suggested to maintain reefs in a coral-dominated state. Examining links between fishes and reef benthos is complicated by the interactions between natural processes, disturbance events and anthropogenic impacts, particularly fishing pressure. This study examined fish assemblages and associated benthic variables across five atolls within the Chagos Archipelago, where fishing pressure is largely absent, to better understand these relationships. We found high variability in fish assemblages among atolls and sites across the archipelago, especially for key groups such as a suite of grazer-detritivore surgeonfish, and the parrotfishes which varied in density over 40-fold between sites. Differences in fish assemblages were significantly associated with variable levels of both live and recently dead coral cover and rugosity. We suggest these results reflect differing coral recovery trajectories following coral bleaching events and a strong influence of ‘bottom-up’ control mechanisms on fish assemblages. Species level analyses revealed that Scarus niger, Acanthurus nigrofuscus and Chlorurus strongylocephalos were key species driving differences in fish assemblage structure. Clarifying the trophic roles of herbivorous and detritivorous reef fishes will require species-level studies, which also examine feeding behaviour, to fully understand their contribution in maintaining reef resilience to climate change and fishing impacts.

Unsaturated Fish Communities in African Rivers

Torrent Ducks (Merganetta armata) inhabit fast-flowing rivers in the Andes. Rainfall causes rivers to swell, increasing water velocity, turbulence, and turbidity. These changes may affect the ducks' foraging ability because of the harsher conditions or alteration of the aquatic macroinvertebrate resource base. We examined the relationship of Torrent Duck time budgets with food availability and rainfall in the central Andes of Colombia. Time spent foraging was not correlated with total macroinvertebrate density but was negatively correlated with density of 4 preferred families. Monthly precipitation was negatively correlated with total macroinvertebrate density but not correlated with the 4 preferred families. Time spent foraging correlated with rainfall the day before. Torrent Duck time budgets result from interactions among several factors: the ducks' foraging tactics, prey type, and river conditions that affect ducks directly, and indirectly through prey availability. Three of the 4 preferred i...

Highway infrastructure is a source of multiple environmental problems, where wildlife roadkills is the most noticeable impact. Most of research in roadkills have focused in how different aspects as seasons, traffic density, location of roads, among others, have implications in the wildlife mortality on roads. However, little research have been developed on understanding how geometrical road design affects wildlife mortality. On a highway in the central Andes of Colombia, we tested whether the geometric design, it is horizontal alignment and vertical curves influence the mortality of vertebrate animals on the road. We determined the number of straight lines, circular, transition curves and vertical convex curves along the entire route of the highway (13.9 km), and between April 2018 and December 2019 we made 4 weekly tours in search of wildlife roadkills. With records, we related and compared groups of animal deaths and road shapes. We got 95 roadkills where reptile’s deaths were more than the 47% of total. We found no dependence in the distribution of deaths by Class of animals on the road shapes; the shape in which most deaths occurred was straight line (58 deaths). However, when the mortality rate per meter of route was obtained on the shape units, we found that the circular and transition curves presented two and three times (respectively) higher mortality rates than straight lines. Curved sections are presented as more dangerous geometric designs than straight lines for wildlife, regardless of their length on the road. Our research provides information necessary to take into account the relationship of geometric road design in the development of management and conservation plans of altered ecosystems with road infrastructure.

Introduction: The department of Caldas is located in the Central Andes of Colombia, it includes a mosaic of environments that originally was conformed by paramos, sub-Andean and Andean forests, and rainforests. Although several studies have contributed to the knowledge of wild felids that inhabit the department of Caldas, Central Andes of Colombia, to date, there are no a publications summarizing the existing information on the felids in this area. The aim of this paper is to review the composition, distribution and conservation status of felids of the Caldas department. Materials and methods: To carry out the review of the composition, distribution and conservation status of the wild cats of Caldas department, were taken into account: A) Specimens, or part of these, deposited within biological collections. B) Records in scientific literature. C) Photographic records. D) Records of live individuals coming from the Caldas department who entered to the Center of Care, Assessment and Rehabilitation of Wildlife of the Regional Autonomous Corporation of Caldas (Corpocaldas). E) Records coming from attacks by wild cats on sheep, cattle and horses within the department. Results and discussion: We identified 33 locations with records of wild felids, which belong to six species: Leopardus pardalis (Ocelote), L. wiedii (Margay), L. tigrinus (Oncilla), Puma yagouaroundi (Jaguarundi), P. concolor (Puma), and Panthera onca (Jaguar). In this work, we identified two areas of the department where most of the records were made. The first area is located in the south-central portion of Caldas and it includes the majority of the records of L. tigrinus and P. concolor . The second area is located in the northeastern portion of the department and it is associated with all of the records of L. wiedii and most of the records of L. pardalis and P. yagouaroundi . The main threats to the survival of wild cats in Caldas are: habitat loss, fragmentation, hunting, as well as road mortality. Since 1999, there are no records of Panthera onca for Caldas, and more research is required to confirm whether this species still inhabits the department.

The Turquoise Dacnis ( Dacnis hartlaubi ) and the Cerulean Warbler ( Setophaga cerulea ) are categorized as “vulnerable” at global scale. Habitat loss and degradation following rapid agricultural expansion and urban development are the main causes of their declines. In this note we present the first documented records of these species in urban green areas in South America. Our observations were undertaken between 2007–2014 during surveys of the avifauna of Armenia City in the central Andes of Colombia. We recorded Turquoise Dacnis on 19 occasions and Cerulean Warbler on 10. Most records were solitary males foraging in Cecropia angustifolia and Inga ornata trees, and some were associated with mixed species flocks. Both species used forest patches, parks and areas with scattered trees. Our observations suggest that cities may provide passage and/or wintering areas for these threatened species.

Daily and seasonal activity of the mountain tapir Tapirus pinchaque was measured along trails and at two salt licks in mature and secondary montane forests of the Central Andes of Colombia using active and passive infrared monitors. Daily activity of the mountain tapir showed a clear bimodal pattern, with maxima during the early hours of the day (5:00–7:00) and early hours of the evening (18:00–20:00). This bimodal activity pattern has also been found in radio-tracking studies of T. terrestris and T. bairdii. Overall, there was more activity in mature than in secondary forest and at lower (3100 m) than higher altitudes (3600 m). Night-time activity was higher during full moon than during quarter and new moons. There was no correlation between monthly rainfall and seasonal activity. The time the mountain tapir was at the salt licks varied between 1 and 190 min. Daily activity at Quebrada Paraiso salt lick (3400 m) showed a clear bimodal pattern with maxima around midnight (0:00–2:00) and midday (11:00–14:00). These patterns of diurnal and nocturnal activity of the mountain tapir could be used in combination with future radio-tracking studies to better understand habitat use by this species.

Daily and seasonal activity of the mountain tapir Tapirus pinchaque was measured along trails and at two salt licks in mature and secondary montane forests of the Central Andes of Colombia using active and passive infrared monitors. Daily activity of the mountain tapir showed a clear bimodal pattern, with maxima during the early hours of the day (5:00–7:00) and early hours of the evening (18:00–20:00). This bimodal activity pattern has also been found in radio‐tracking studies of T. terrestris and T. bairdii. Overall, there was more activity in mature than in secondary forest and at lower (3100 m) than higher altitudes (3600 m). Night‐time activity was higher during full moon than during quarter and new moons. There was no correlation between monthly rainfall and seasonal activity. The time the mountain tapir was at the salt licks varied between 1 and 190 min. Daily activity at Quebrada Paraiso salt lick (3400 m) showed a clear bimodal pattern with maxima around midnight (0:00–2:00) and midday (11:00–14:00). These patterns of diurnal and nocturnal activity of the mountain tapir could be used in combination with future radio‐tracking studies to better understand habitat use by this species.

Mixed bird flocks are groups of individuals from different species that travel and forage together. Such groups are common in several bird communities around the world. We present species composition and activity patterns of mixed bird flocks in a region of the Central Andes of Colombia. We compared the number of species per flock, as well as the number of flocks among 3 different habitats. We tested hypotheses concerning the flocks daily activity and the co-occurrences of species within them. We recorded 75 species, and the species number per flock varied from 4 to 21. Our data suggest that habitat affects the number of flocks but not their species number, and that the activity of flocks is similar throughout the day. In addition, the association of birds in flocks is affected by interspecific facilitation, with some species co-occurrences found more times than expected by chance. We hypothesize that some tanager species could have a role in flock cohesion. We witnessed 2 predator attacks upon flocks, a number of agonistic interactions among flock members, and squirrels following bird flocks. Our results meet some general patterns described for mixed bird flocks.