During the Tropical Biology Field course (2020) for three weeks we attended great lectures of various topics of tropical evolutionary ecology in terrestrial and marine ecosystems. The lectures preceded a brainstorm session to state a research questions in order to develop a short project for a 2-3 days. During these three days we worked 16-19 hours a day collecting data in the field, doing laboratory work, analyzing data and finally presenting our results using R markdown. On the third week and final project of the course, after a long workday, collectively all us students created the new habit of looking at the beautiful sunset and the stars in Coibita.
Even though field work take researchers to harsh environment with limited commodities during long working days, is satisfactory to have the opportunities to experience invaluable natural spectacles such the Coibita beautiful night sky. We luckily have good weather with clear sky during almost all nights of our stay in Coibita. One night all of us lay on the wet grass to admire the sky while listening the mosquitos flying by. I hope this post described the quiet nights of quiet stars experienced in Coibita.
We will live eternally in this mood of reverie away from all the earthly cares around us
The appearances of bats tend to make us feel very unrelated to them. It is hard to think of a social or economic beneficial of bats to humans, since for century they have been associated to blood sucking vampires and more recently as potential reservoir hosts and vectors of diseases or parasites (Klimpel & Mehlhorn, 2014). Bats are highly diverse worldwide, showing astonishing morphology, lifestyles feature and feeding behaviors that are related to their importance in ecological functions such as pest control, seed dispersal and soil fertilization. During the Tropical ecology course during a lecture and field night observation, we were introduced to the bat’s high diversity in Panama and its importance. Based on our interest and curiosity we decided to explore and discuss the functional importance of bats to human economy and health, in order to break current negative view to these organisms.
Bats as effective pest management
Recent studies (Kolkert et al., 2020; Whitaker Jr & Odegard, 2019) in insectivorous bats sustain their potential as crop’s pest controls. This service of control of plagues can be valued in trillions of dollars globally through the decrease of crops damage, reduction of the use of chemicals, and increasing the yield. It is estimated that a bat can eat 30%-100% of its body weight in prey every night. Bats like to feed on places where there is an abundance of prey, such as areas in crops where there is an outbreak of plague (Kolkert et al., 2020). Advances in molecular methods have facilitated the precise identification of the diet of these bats, thus allowing them to establish predator-prey interactions. Kolkert et al., (2020) applied the Metabarcoding methodology to identify how diverse the insectivorous community was in transgenic cotton crops and what type of insects (benefits or pests) are consumed by bats. The study evaluated the effectiveness of insectivorous bats as plague controllers through the investigation of their diets. Bats were captured at the limits of cotton plants by using mist nets and harp traps. They were placed in bags and kept until the next nightfall. Fecal pellets (2-8) were removed from each of the trapped bats. A total of 58 individuals from 7 different species of insectivorous bats were captured. Of the total of individuals captured, only in 24 the sex was identified, 50% male and 50% female.
Figure 1. View of Phyllostomidae (Artibeus jamaicencis) bat captured in Gamboa on the STRI Laboratory.
Kolkert et al., (2020) stated that the most prefer insects by bats included: Lepidoptera (moths), Coleoptera (Bettles), Homoptera/Hemiptera (true bugs), Orthoptera (grasshoppers amongst others), Diptera (flies), Araneae (spiders) and Ixodidaes (ticks). Moreover, they concluded that moths are in important component of bat’s diets; however, bats determine what to eat based on the availability of food. For instances, Cicadellids where an important component of bat’s diet when they were most available. Cicadellids contribution to bats diet in September was very limited (up to 1.5%), this behavior corresponded with the low availability of Cicadellids during this month. Similarly, insects such as beetles and true bugs were consumed in less quantity during September. Another conclusion reached by Kolkert et al., (2020) was that small insects (such as flies) with less energy in relation to the energy expended by them during the predation process were captured in lower amounts even when vastly available. Species of flies of greater size were the most preferred.
Bats guano as a source of fertilizers
Bats feeds on various sources from fruits, insects, fish, mammals and blood. One interesting fact is that most bats often have a special place where they eat and consequently defecate, accumulating massive amount of fecal matter (guano) in a single place. Due to this behavior people have taken advantage to collect large amount of guano to fertilize poor soils for agriculture. Guano is rich in nitrogen, phosphorous and potassium which are principal components for plant growth making them an inexpensive natural resource for local agriculture. Guano was used extensively around the globe before the production of artificial fertilizers in 1915. In the 1800s century mining for Guano cause the destruction of bat caves and consequently reduction in guano production in Peru after the monopolization of the resource. Extensive mining of guano in caves can negatively impact bats caves in various ways and the ecosystems it beholds. This critical situation made the International Union for Conservation of Natures (IUCN) in 2014 to create sustainable mining policies. Sustainable extraction of guano in developing countries could be a solution to boost local agriculture where buying artificial fertilizers represent a relatively big expense causing negative incomes in their local productivity.
Bats pollination to improve tequila production
The mention that bats are great pollinators is often accompanied by images of them visiting flowers in the forest or somewhere distant without establishing a direct connection with the applicability of their role to our daily lives. An example that shows us how these winged companions, in exercising their natural function, are capable of affecting our economy is the relationship of some species of Mexican bats with agave plants (Agave sp.), responsible for generating tequila. These bats are one of the main pollinators of agave (Trejo Salazar et al., 2016), however, due to the techniques that some producers use for their cultivation, agave populations have low genetic diversity (since they do not allow them to flourish and the production of more agave is carried out asexually) (Eguiarte et al. 2013), this makes the crops a vulnerable target for the attack of pathogens and as a side effect can reduce the availability of food for these nectarivores bats. A fairly novel method proposed to solve both problems lies in allowing at least 5% of the agaves in one hectare to flourish, thus giving, on average, nectar to 89 bats per night. Taking into account the amount of agave hectares in Mexico, it was estimated that this could represent food for more than two million bats per month and at the same time increase the genetic diversity of both agave crops and wild populations of the genus that are also threatened by their low levels of genetic diversity (Trejo Salazar et al. 2016). The producers who have adopted these measures are benefited with a label that certifies that their tequila is “Bat-friendly” (figure 2), which gives them an added value to their product while supporting the conservation of two wonders of this world, bats and tequila.
Figure 2. Logo of bat-friendly tequila Project.
References
Eguiarte, L. E., Aguirre-Planter, E., Aguirre, X., Colín, R., González, A., Rocha, M., & Souza, V. (2013). From isozymes to genomics: population genetics and conservation of Agave in México. The Botanical Review, 79(4), 483-506.
Klimpel, S., & Mehlhorn, H. (2014). Bats (Chiroptera) as Vectors of Diseases and Parasites. Facts and Myths. Springer, 1-187.
Kolkert, H., Andrew, R., Smith, R., Rader, R., & Reid, N. (2020). Insectivorous bats selectively source moths and eat mostly pest insects on dryland and irrigated cotton farms. Ecology and Evolution, 10(1), 371-388.
Trejo-Salazar, R. E., Eguiarte, L. E., Suro-Piñera, D., & Medellin, R. A. (2016). Save our bats, save our tequila: industry and science join forces to help bats and agaves. Natural Areas Journal, 36(4), 523-530.
Whitaker Jr, J. O., & Odegard, D. (2019). Food of the Free-Tailed bat, Tadarida Brasiliensis, from congress avenue Bridge, Austin, Texas. The Southwestern Naturalist, 64(1), 20-22.
For a long time naturalists have described species using a detailed written descriptions and illustrations to fully present their observations. Before the availability of photographic technologies, naturalist depend on detailed drawings to described microscopic organisms that otherwise will have been impossible to illustrate. In the current modern world high quality photography of organism macroscopic and microscopic features have added a new way for scientific illustrations. Despite of modern photographic devices available, natural history artworks are far from disappearing due to the beauty they enclosed in the details.
An example of beautiful scientific artwork are in the work of the German Biologist, naturalist, philosopher and physician, Ernst Heinrich Haeckel. He illustrated how various microscopic organisms’ forms appear through brilliant colorful and detailed drawings and watercolors. These cryptic organisms would not have been regarded if it was not for Haeckel illustrations. His work not only contributed to the description of many unknown species at the time, but also by capturing science in fantastic artwork outreach the world about these microscopic organisms.
In humid tropical forest nearly, all surface get cover by cryptic organisms such as mosses (Bryophytes). Some bryophytes tend to colonize leaf surface in tropical forest where high number of species co-exist. Most of these species tend to have a small size ranging from 0.1-2.0 mm, that might go unnoticed even for well-trained botanist. They represent less conspicuous organisms but albeit equally important component of tropical forest. In the context of describing the cryptic diversity of epiphyllic organisms in tropical forest I made line drawings, acrilyc and oil paintings of several liverwort species that are presented below.
Line drawing of the liverwort genus Ceratolejeunea habit.
Habit of the common epiphyllous liverwort Cololejeunea surinamensis. A. Macro photography. B. Microscopic photography. C. Acrylic painting.
Representation of an epiphyllous liverwort habit in oil painting
Identifying the processes underlying succession has been a central challenge in ecology for more than a century (Cowles 1899). Succession, traditionally defined as species replacement through competition along a temporal gradient (Drury and Nisbet 1973), is fundamentally a demographic process governed by variation in recruitment, growth, reproduction and local extinction (Peet and Christensen 1980). Repackaging succession into assembly rules refined it into three non-mutually exclusive processes: dispersal, abiotic environment and biotic interactions (Götzenberger et al. 2011). A clear understanding of how community assembly in nature will led to better reforestation policy to mitigate habitat degradation, especially in landscapes where are high socioenvironmental benefits and feasibility (Brancalion et al. 2019).
Despite the importance of successionary dynamics, the long-life cycle, uncertain habitat boundaries and difficulty to carry out replicative experiment in most plant communities, preclude to collect sufficient data to disentangle ecological processes behind succession. Landscape-scale studies exploiting rare geological events such as volcanic eruptions (del Moral et al. 2012), or anthropogenic disturbance (Wassenaar et al. 2005) are examples of effective natural plant community assembly experiments however they suffer from replicability.
The Agua Salud project offers a unique experimental design, taking in to account historical land use and experiment replicability in order to explore successionary dynamics along a chronosequence (van Breugel et al. 2013). During a visit to the Agua Salud porject in the Colon province in Panama, we explored the different research carry out through the eleven years of the project. The results have greatly increased our understanding of the ecosystem services in different types of forest regarding hydrological, carbon sequestration and biodiversity at a landscape scale (Stallard et al. 2010). This project have focus mainly of the hydrology in the landscape, one of the principal resource of the Panama Canal watershed. Water enables the ships transit through the canal, generating hydroelectrical energy, and supply water for major urban and rural areas in Panama and Colon province. In Panama the dry season are becoming longer and severe, while in the wet season severe storms will be more frequent as a consequence of climate change. Forest restoration along the watershed, to date is the best policy to withstand hydrological intrinsic effects related to climate change in the Panama Canal. Implementing this policy will prevent economic, social and environmental catastrophe regarding water availability in the Canal watershed.
Figure 1. Agua Salud Project landscape view from the Meteorological station. The landscape is composed of different ages of secondary forest and timber plantations.
Agua Salud project also focus on smart reforestation with native species of economic importance in the timber industry. This project is unique due to the various types of reforestation treatments in their landscape. One of the papers published from long term observation of monocultures and various degree of interacting species, multicultures with up to five timber species (Mayoral et al. 2017). Interestingly their research show that five native species (Anacardium excelsium, Dalbergia retusa, Pachira quinata, Tabebuia rosea and Terminalia amazonia), differing in key functional traits, were better growing in five species mixture, indicating a diversity effect. Also in some treatments with the nitrogen fixer Dalbergia retusa facilitate the growth of co-habitat species Pachira quinata.
While walking on the Teak plantations, we also observed individuals with ~2-3 years native species almost as high as 11 years old Teak trees. The soil in the Agua Salud landscape are very poor on nutrients (specifically in Phosphorus and Nitrogen), where Teak performs poorly. Taking advantage of this multiculture approach, will not only result in improvement of the land commercial value for the timber industry, but also enhancing ecosystem services in the Panama Canal watershed (Mayoral et al. 2017). Agua Salud represent a fast-growing experiment that seeks to understand basic ecological question to inform conservation policies in tropical forest.
Figure 2. Dr. Jefferson S. Hall standing beside a three year old Dalbergia retusa (Cocobolo) growing amazingly great within poorly growth Tectona grandis (Teak) plantation.
REFERENCES
Brancalion, P.H.S., Niamir, A., Broadbent, E., Crouzeilles, R., Barros, F.S.M., Zambrano, A.M.A., Baccini, A., Aronson, J., Goetz, S., Reid, J.L., Strassburg, B.B.N., Wilson, S., Chazdon, R.L. 2019. Global restoration opportunities in tropical rainforest landscapes. Sci. Adv. 5, eaav3223.
Cowles, H.C. 1911. The causes of vegetative cycles. Bot. Gaz. 51: 161–183.
del Moral, R., Thomason, L.A., Wenke, A.C., Lozanoff, N., Abata, M.D. 2012. Primary succession trajectories on pumice at Mount St. Helens, Washington. Journal of Vegetation Science 23: 73–85.
Drury, W.H., Nisbet, I.C.T. 1973. Succession. Journal of the Arnold Arboretum 54: 331–368.
Götzenberger. L, de Bello, F., Bråthen, K.A., Davison, J., Dubuis, A., Guisan, A., Lepš, J., Lindborg, R., Moora, M., Pärtel, M., Pellissier, L., Pottier, J., Vittoz, P., Zobe, K., Zobel, M. 2011. Ecological assembly rules in plant communities approaches, patterns and prospects. Biol. Rev. 87 :111–27.
Mayoral, C., van Breugel, M., Cerezo, A., Hall, J.S. 2017. Survival and growth of five Neotropical timber species in monocultures and mixtures. Forest Ecology and Management 403: 1–11.
Stallard, R.F., Ogden, F.L., Elsenbeer, H., Hall, J.S. 2010. Panama Canal watershed experiment: Agua Salud Project. Water resources impact 12: 17–20.
Peet, R.K. & N.L. Christensen. 1980. Succession: A population process. Vegetatio 43: 131–140.
van Breugel, M., Hall, J.S., Craven, D., Bailon, M., Hernandez, A., Abbene, M., van Breugel, P. 2013. Succession of Ephemeral Secondary Forests and Their Limited Role for the Conservation of Floristic Diversity in a Human-Modified Tropical Landscape. PLoS ONE 8: e82433.
Wassenaar, T.D., van Aarde, R.J., Pimm, S.L., Ferreira, S.M. 2005. Community convergence in disturbed subtropical dune forests. Ecology 86: 655–666.
STRI'S TROPICAL BIOLOGY FIELD COURSE 