The lake group. The Secchi disc test has been an important tool at Lake Tahoe for tracking clarity trends. The white disk is dropped in the water, and the depth that the disk becomes invisible is recorded. The disc is dropped deeper, then brought back up to the surface slowly. The depth at which the disk becomes visible is also recorded. When this test is conducted over time, trends emerge that provide one indicator of lake health.
Photo: Students using the Secchi disc
The measurements of clarity are important for us to understand where different production of algae may be occurring in Lake Atitlan. Currently sewage goes directly into Lake Atitlan, unlike Lake Tahoe where it was exported from the basin in the 1970’s. This sewage input has likely resulted in the cultural eutrophication of Lake Atitlan which is the increased nutrient loading due to human activities resulting in increased algae growth. Using the Secchi disk exactly like the one we use at Tahoe allows researchers at Atitlan determine where the algae growth may be occurring.
The students enjoyed using equipment they have not had access to up until this time. In addition to the Secchi disc, open, tubular canisters called Van Dorn samplers were dropped (with the precious heavy, winch we packed with us) to selected depths.
Photo: The winch, with GPS for tracking lake depth information
When the canister reached the desired depth, a “messenger” is dropped down after it which closes the top and bottom of the canister, trapping the water inside. The canister is then brought to the surface and water is collected for water quality analysis (nutrients, phytoplankton composition).
Photo: Students learning about the Van Dorn sampler, with Bob Richards teaching
Photo: water from canister being run through a filter
Temperature and pH was recorded through the use of a hydrolab.
Photo: Annie Caires putting the hydrolab in the lake
Photo: As a team, students helped track the data from the hydrolab.
Large plankton nets or large filters that sieve the water were also dropped into the water to collect phytoplankton.
Photo: Bob Richards showing students how to use the large filter.
Jana, a PhD student from the University of South Bohemia, uses some of the water to look for algae. The algae viewed under the microscope. Jana says she enjoyed having power on the boat so they can power their microscope lights to look at the algae which come in all type of sizes and structures that are used to identify them. They are looking for cyanobacteria, specifically the genus Lyngbya that has been implicated in changing the ecology and clarity of the lake. The researchers are concerned this cyanobacterium could transform the lake and cause health problems for the local people. In other lakes, cyanbacteria can produce toxins or create habitat for bacteria like E. coli that cause sickness.
Photos:
1. Dr. Komarek reviewing samples
2. A Guatemalan student receiving training from Dr. Komarek
3. Jana working with a sample
4. The slide under the microscope
Watershed/ engineering group. Another group visited communities around the lake to see key places where water enters Lago de Atitlan. Near Santa Cruz, the sewage that used to be treated with a constructed wetland system is currently running directly into the lake … practically untreated. It is a very alarming sight, and reminds us of our history with Lake Tahoe. It was absolutely critical to prevent the flow of sewage into the lake.
Photo: Sewage entering Lago de Atitlan
The hope for the group is to identify the primary locations that need updated sewage plants and simple technologies that can assist in removing nutrients from sewage. Rob Collison, a recent PhD graduate from UC Davis, is leading this effort.
Chemistry group. A third group was in the chemistry laboratory, getting the lab ready and chemicals prepared so that the many samples taken during the day could be analyzed for nutrients. One of the primary needs in this area is to have reliable chemical assays that will allow researchers to determine the season variability in nutrients and how they limit the algal growth. Thanks to the funding from the US National Science Foundation and private donors some of the supplies brought here may be utilized in the future to assist our colleagues in measuring nutrients.
Certain specialists will remain in their group, because their expertise is critical. The students will rotate every few days so that they can gain experience in several areas. For these first few days, the students were given the opportunity to select the group they joined.
Eliska Rejmankova, UC Davis
This was the first day in the field and in the lab. Everything is going quite smoothly, and the group leaders are all amazed by the skills and enthusiasm of the Guatemalan students. There is a lot of positive energy floating around.
Sudeep Chandra, University of Nevada- Reno
The first day of field and laboratory work was absolutely critical for the success of this project. It is amazing how much support and enthusiasm there is for this project. The students are absolutely incredible here. They are curious and their professors have prepared them well for this experience. The lake itself is amazing. While there are a lot of similarities to Tahoe (deep lake, clear water during this time of year), the volcanoes that spire above the lake make this one of the most picturesque places I have ever traveled. The water is much warmer since it is in a tropical region of the world and as a result seems to contribute to the productivity of the lake. I have travelled to quite a few Arctic and temperate lakes but am thoroughly enjoying trying to understand the ecology of this large tropical lake with my Guatemalan colleagues. More tomorrow, it is late and we have been up since 5 am!
Robert Collison, University of California, Davis
Our watershed and waste water group took submerged macrophyte (underwater weeds such as elodia) samples from the 3 meter lake level. We also took water, soil, and plant samples from the lower reaches of the river. The eroded river bank clearly showed the stratified flood plain material with alternate layers of sand and cobble, but limited fines (silt) and insignificant clay.
Next, we visited the waste water treatment plant in Santa Cruz (population: approximately 3,000) which is currently closed for remediation. The primary treatment is being improved with the addition of an Imhoff tank, but the secondary treatment is being modified by removing a constructed sand and gravel wetland and replacing it with trickling filters, using the same concrete banks but now to be filled with plastic media. The media to be used is very large (15 cm diameter) and will provide significantly less surface area for biological colonization (bacteria are critical if the wetland is to actually “process” waste water). I believe that this will detrimentally affect the treatment. Alternatively, if the plastic media were replaced with a single-sized gravel, the trickling filter delivery system would provide much better organic material removal, and probably nitrogen too. I hope that the plastic media will be quickly replaced.
Amber Roegner, UC DavisQue día de aventura! Acompane a Tereso Joj, uno de los Coordinadorios de UVG Altiplano, y dos mujeres con quien trabajaba en la comunidades para tomar muestras locales del agua de San Pedro, San Lucas, y Santiago de Atitlan (que se usaba agua directamente del lago), mientras los restos hablaban con los alcaldes y oficiales de cada pueblo para coordinar una visita en cada sitio para que hablemos con los maestros de las comunidades mas afectadas por las floraciones.
Primero llegamos a San Pedro, donde había una reunión con el alcalde en que participe. Tereso me muestró al alcalde como uno de los científicos que les quiere ayudar, pero también que quiere ser educada por ellos. Pues amablemente, el alcalde llamó a un hombre que trabajaba en la oficina central para llevarme para colectar la muestra. Fuimos por moto (botellas casi cayendo atrás) y nos reunimos con otro hombre para andar casi un kilometro para llegar hasta el hondo en que mezcla el agua de la montana y el agua colectado del lago. Saqué muestras para analizar el fosforo y nitrógeno y también mas tarde cuando regresaré a UC Davis, lo analizamos por niveles de tóxicos de cianobacterias. Los dos hombres con que viajaba me preguntaron mucho sobre las floraciones y traté de responder a sus preguntas lo mas posible con lo que sabía. Cuando regresamos por fin con las muestras al centro y reunimos con los otros.
Seguimos por alrededor del Lago de nuevo en coche, y Tereso me contaba mucho de las poblaciones nativos del area (K’iche, K’aqchikel, y Tz’utchi); Tereso es un tesoro de conocimiento de la cultura, de veras. . Ademas nos divertimos mucho juntos. Durante estaba en una reunión con el alcalde de San Lucas, el conductor del automóvil y yo regresamos a colectar agua de Santiago de Atitlan. El ingeniero de la ciudad me mostro el tanque de colleccion cerca del agua y me ayudo colectar muestras directos, sin cloro y después del tratamiento de cloro.
Durante esperamos que los otros regresan, tuve la oportunidad de hablar un poquito con Cesar (“Cheche”) nuestro conductor y estudiante de UVG. Ademas de hablar del futbol local e internacional, le pregunte a que te parece la condición del lago. Aunque se preocupaba mucho, tenia ganas de luchar por la protección del lago y tenia el mucho orgullo en su tesoro nacional.
Por fin Tereso y los otros de UVG Altiplano y yo fuimos para colectar agua de San Lucas directamente de la cuenca. Dedicado a tomar fotos de nuestra aventura, Tereso me seguió por una tuveria para tomar foto de mi collecion. Desafortunadamente se cayó por el agua del lago! Solo si tuviera la camera para tomar la foto suya!
