At night, the respiration of consumers (zooplankton, macro-invertebrates, fish, among others) also depletes oxygen, which can become limiting in the early morning. Under extreme conditions, certain green microalgae and cyanobacteria can proliferate. They form a surface layer (‘bloom’) that does not allow solar radiation to pass in depth and inhibits the exchange of oxygen with the atmosphere. Lack of background light impairs the survival of submerged plants (macrophytes), such as charas, which also consume nutrients and oxygenate the water. Around, the reduction of dissolved oxygen, already reduced by 30% by height in relation to sea level, is deadly for these consumers.

The evolution of this subtle balance of processes deserves to be studied to anticipate future lake responses, and to develop measures to control undesirable phenomena. For this, the behavior of key parameters in the water needs to be monitored / monitored. The most important are: the concentration in dissolved oxygen (-), the temperature gradient (+) (the increase in temperature reduces the solubility of oxygen), the concentration in dissolved organic matter (+), the transparency (-) or turbidity (+), pH (+), chlorophyll-a concentration, the highest photosynthetic pigment in algae (+), the proportion and concentration in cyanobacteria in phytoplankton (+), conductivity (+). Increasing (+) or decreasing (-) these parameters reveals a deterioration in water quality, called ‘eutrophication’. This does not take into account the pollutants themselves. These parameters are influenced by atmospheric conditions, such as: the force of the wind capable of mixing and cooling the water column, the intensity of solar radiation (altered by cloudiness) that warms the surface, the atmospheric pressure that regulates the dissolution of the oxygen, rainfall (rain, snow, hail) that provides nutrients, among others. The responses of microorganisms (micro-algae, bacteria) to variations in environmental conditions are extremely fast. They are able to double their densities in hours or days. Measurement campaigns and sample collections are time consuming, require logistics (vehicle, ship, equipment) and are expensive. They can only be done 1-2 times a month, and part of the year. It is insufficient to anticipate the dynamics of these organisms and the eutrophication phenomena. For this reason, it is necessary to complete the regular campaigns in some representative stations with automatic high-frequency sampling in the entire water column in a central station that integrates the variability of conditions in the area of ​​interest. Advances in technology, improved sensitivity and miniaturization of sensors, reliability of probes, robotics, computer programming, Internet, speed and coverage of the cellular network, greater efficiency of solar panels, now allow the design of platforms perfectly autonomous and automatic. The buoy deployed in Lake Menor is the example. The transmission of data via ENTEL's cellular network to our servers at UMSA in La Paz, allows us to have an almost real-time view of the lake, being able to take action if necessary. With this technology, Lake Titicaca is now instrumented (equipped) like most of the other Great Lakes in the World.

Where is 'My Buoy' Located?

The Northeast region is the shallowest, most populated region of Lake Menor, where the proliferation of phytoplankton micro-algae occurred in April-May 2015. In this region, the daily heating of the shallow body of water invariably causes thermal winds that increase its intensity in the early afternoon. They can reach speeds of up to 10 m / s, enough to mix the water column up to 5 m deep. This mixture causes the resuspension of the nutrients and organic matter deposited in the bottom. This phenomenon makes this region the most favorable in generating proliferations (‘blooms’) of micro-algae of the phytoplankton. For this reason, she was chosen to deploy the buoy. It is anchored at a depth of 13 m, possibly in the northern branch of the Katari river, in an area of ​​8 m depth on average. This location allows studying the dynamics of daily vertical gradients in dissolved oxygen, temperature, organic matter and chlorophyll-a, generated by meteorological conditions.

The inaugural Lacustrine Ceremony of 'My Buoy'.

To present 'My Buoy' and its operation to State institutions, local authorities and riverside populations, an inaugural Lake Ceremony was organized on Friday, June 28, 2019. As this Buoy measures both hydrobiological and meteorological parameters, it was called 'HidroMet' buoy in technical language. For the general public it is ‘Mi Boya’ because it is a heritage of the inhabitants of the Lake that informs them of their state of health. It also has its Aymara name ‘Qamaskiua ch’uwa quta mama’, chosen by the riparians themselves.
The welcoming words were given by Eng. Isaac Callizaya Limachi, Secretary of Environment and Cultures of Puerto Pérez. Representatives of the Institutes of Ecology (IE), Hydraulics and Hydrology (IHH), Chemical Investigations (IIQ) and Geographical Investigations (IIGEO) of the UMSA, the Operational Unit of Bolivia (UOB), the Katarí Basin Management Unit participated. (UGCK) and the General Directorate of Planning (DGP / UEE) of the MMAyA, Mr. Grover Huallpa Aruquipa, coordinator of the IWRM project at the Bolivian Chancellery (MRE), Mr. Rolando Urahola, Director of the Decentralized Public Institute of Fisheries and Aquaculture (IPD-PACU) for the Altiplano, technicians from the National Service of Meteorology and Hydrology (SENAMHI), the communicator of the La Vida project, Eng. Valentin Fernández, Director of the ALT Master Plan and technicians, Prof. Eliana Ballivian Ríos, communicator of the IWRM project, Prof. Analía Guachalla Terrazas, coordinator of the technical liaison for Bolivia, Eng. Gonzalo Lora Viezaga, ex-binational scientific coordinator of the IWRM project, Mr. De nis Gaillard, Ambassador of France in Bolivia and Mr. Patrick Riba, Head of French Cooperation, Eng. Cenaida Ramos Poma, representing the National Water Agency in Puno Peru, Arch. Hugo Zea Giraldo, coordinator of the QOTATITI platform of the Peruvian society, the local authorities of Puerto Pérez, Mr. Felix Mendoza Secretary General of the Quehuaya Island, Mrs. Virginia Mamani of the Isla Suriqui Bartolina Sisa Agrarian Central, from Huatajata and Tiquina, with journalists from the press : Canal 13 TV Universitaria, RTP Bolivia, the Foundation for Strategic Investigation in Bolivia (PIEB), the Association of Journalists of La Paz, and France 24. On Google, view notes and video reports, with the words 'Titicaca buoy'.
Next to the buoy, Comadre Adela, Copacabana Spiritual Guide, held an ancient lake ceremony of good omens for the team, participants, institutions, research projects, monitoring and restoration of the Lake. Mr. Lorenzo Inda, Uru representative in Desaguadero, welcomed on the floating totora island of Quehuaya, communicating the concern of the coastal towns regarding the increasing contamination. In total there were 60 participants, aboard 3 boats piloted by Messrs. Natalio and Ariel Esteban, from Suriqui, and Máximo Catari Cahuaya from Huatajata.

The Bolivian Navy supported with a ship from the Huatajata Captain's Navy. On board the buoy, Ing. Sterling and Dr. Lazzaro, described the technical characteristics of the buoy, the parameters to be measured, the frequency of data acquisition, what it is for, the benefits for the inhabitants, scientists and decision makers, and why was it deployed in this area? Due to the strong waves and wind, it was not possible to show the operation of the different internal elements of the buoy, such as the vertical profiler and the multiparameter probe. Despite the use of megaphones, it was difficult to communicate with the audience on the boats. For this reason, after a trial period of about two months, another technical workshop will be organized on the Cota Cota UMSA Campus, to train teams from the UMSA, MMAyA, SENAMHI and ALT, among others.

Reaching the final design of 'Mi Boya' took three years. First, the availability of equipment in the market, characteristics, performance, durability, costs and experiences in other instrumented ecosystems had to be raised. The large global manufacturer XYLEM Analytics Inc. was selected, the only one capable of combining the latest state-of-the-art equipment from the market's leading brands to create innovative custom systems that meet user requirements. The intense collaboration between Sterling (XYLEM) and Lazzaro (IRD) resulted in the following design, combining the best of the leading brands:

- A 3.6 x 2.0 m pontoon platform, more comfortable for maintenance than a spherical buoy.

- A complete ultrasonic weather station, with no moving parts.

- An underwater multi-parameter probe equipped with key sensors to assess the eutrophication level, mounted on a programmable vertical profiler to characterize the entire water column.

Our technical and cost / performance analysis led us to select the Polimater / BASEFLOW / XYLEM XYLEM HydroMet Profiler Pontoon / Raft buoy, with a digital sonic Vaisala 202133 weather station and a submersible YSI EXO2 multi-parameter probe. Polimater / BASEFLOW is the official supplier for Latin America of renowned manufacturers, such as YSI, Campbell, Vaisala, SonTek, WaterLOG, Aanderaa, among others. XYLEM Analytics is a leading global manufacturer and assembler of leading market brands, whose success is based on innovation and application within the water and wastewater sectors.

Types of buoys and equipment available in the international market

To select the models and brands of the buoy and both meteorological and water quality sensors, a tender was made for the equipment available on the international market, comparing their technical characteristics and costs. We compare the teams of the leading brands:

	- OTT HydroMet, GmbH / Hach Company, Kempten, Germany: OTT Water Quality Buoy and HYDROLAB HL7 multiparameter probe (temperature, conductivity, pressure / depth, pH, dissolved oxygen, turbidity, ORP, cyanobacteria, chlorophyll-a; www .ott.com
	- DMO - Del Mar Oceanografic, LLC, San Diego, CA, USA USA USA USA: vertical profiler ‘THE WIREWALKER ™, powered by the energy of ocean waves; www.delmarocean.com
	- EIVA Marine Survey Solutions, Skanderborg, Dinamarca: ToughBuoy Pancha wave buoy solution para estudios de medición de olas y corrientes; www.eiva.com/products/eiva-equipment/toughbuoy-panchax
	- NKE Instrumentation, Hennebont, Francia: NKE Boya instrumentada genérica, transmisión de datos por enlace de radio o red de telefonía celular mediante protocolo TCP-IP, almacenamiento > 1 año; medición de parámetros de agua: temperatura, corrientometría, nivel de agua, conductividad, oxigeno disuelto, turbidez, pH, clorofila; parámetros meteorológicos: velocidad y dirección de viento, temperatura del aire; NKE Boya perfiladora mejorada del modelo inicial PROLIPHYC: sonda multiparmétrica MP (temperatura, presión, conductividad, OD), sonda FluoroProbe BBE5 (fluorescencia de la clorofila-a) con sistema de cloración; estación meteorológica Vaisala: irradiancia solar, velocidad/dirección del viento, temperatura, presión atmosférica, pluviometría;www.nke-instrumentation.fr
	NKE Improved roll buoy from initial model PROLIPHYC
	- Polimater LLC / BASEFLOW / XYLEM Analytics, Doral, FL, USA: YSI EMM68 Harbor Buoy: Rapid deployment water quality monitoring platform with remote telemetry, can be lifted by 2 people, operable from a small boat; XYLEM HydroMet Profiler Pontoon / Raft - combines a complete multi-parameter sonic Vaisala weather station (wind speed-direction, rainfall, solar radiation, humidity, atmospheric pressure) with a submersible multi-parameter YSI EXO2 probe (depth, conductivity, temperature, pH / ORP, Optical OD, turbidity, fDOM, Chlorophyll-a and Phycocyanin fluorescence, with cleaner) mounted on a programmable vertical profiler; buoy equipped with GPS, dataloggers, GSM transmission, powered by solar panels;www.baseflow.net
	XYLEM HydroMet Profiler Pontoon/Raft

What Parameters does 'My Buoy' measure?

The Vaisala 202133 weather station is equipped with a suite of all digital sonic sensors with no moving parts. It measures 5 of the most essential meteorological parameters and solar radiation:

- Speed (range 0-60 m / s, response time 0.25 s, available variables: average, maximum and minimum, precision ± 3% at 10 m / s, resolution 0.1 m / s) and wind direction (azimuth 0-360º, response time 0.25 s, available variables: average, maximum and minimum, precision ± 3.0º at 10 m / s);

- Duration (counting each 10-second increment each time a drop is detected, resolution 10 s; hail: cumulative number of hits against the collection surface, duration: counting each 10-second increment when detects hail, resolution 0.1 hits / cm2, 1 blow) and intensity of precipitation (accumulative accumulation after the last automatic or manual restart, running an average of 1 min in steps of 10 seconds, observation range 0-200 mm / h, resolution 0.1 mm / h, collection area 60 cm2, output resolution 0.01 mm, accuracy better than 5% depending on the climate; intensity: average run time of 1 min in steps of 10 s, hail resolution 0, 1 hits / cm2h, 1 hit / h);

- Barometric pressure (range 600 to 1100 hPa, precision ± 0.6 hPa from 0 to + 30ºC) : Barometric pressure is the value of atmospheric pressure that is measured in any point above sea level.

- Relative humidity (0 to 100% RH, accuracy ± 3% RH at 0-90% RH, + 5% RH at 90-100% RH) : Relative humidity (RH) is the ratio of the partial pressure of water vapor to the equilibrium vapor pressure of water at a given temperature.

- Air temperature (-52º to + 60ºC, precision at +20 ºC ± 0.3ºC) : The temperature is an index indicative of the resulting heating or cooling of the air of the heat exchange between the atmosphere and the earth.

- Incident solar radiation using a Li-200 R pyranometer sensor (accuracy 5%, typically <3%, sensitivity ± 1% of linearity). : Solar radiation is the set of electromagnetic radiation emitted by the Sun. Solar radiation is distributed from infrared to ultraviolet. Not all radiation reaches the surface of the Earth, because the shorter ultraviolet waves are absorbed by gases in the atmosphere.

The YSI EXO2 multiparameter probe is the most advanced platform for monitoring water quality. Have a depth range of 0-250 m, autonomy of 90 days with an acquisition frequency of 15 min and a frequency of up to 4 Hz. It houses 7 ports, 1 for the antifouling cleaner and 6 for sensors of:

- temperature (precision 0.001 mS / cm and resolution 0.0001 to 0.01 mS / cm) : The electrical conductivity of water also depends on the temperature of the water: while the higher the temperature, the higher the electrical conductivity. The electrical conductivity of water increases by 2-3% for a 1 degree Celsius increase in water temperature

- >pH / ORP (range -999 to 999 mV, precision ± 20 mV, resolution 0.1 mV) : pH is a measure of acidity or alkalinity that indicates the amount of hydrogen ions present in a solution or substance. ORP is a measure to know the reduction and oxidation capacity of the material.

- chlorophyll-a and phycocyanin (cyanobacteria) combined in a single sensor (range 0 to 100 µg / L, resolution 0.01 µg / L) : Cyanobacteria, formerly Called blue-green algae, they are an edge of the Bacteria domain that includes bacteria capable of oxygen photosynthesis. They are the only prokaryotes that carry out this type of photosynthesis, which is why they were also called oxyphotobacteria.

- fDOM (fluorescence of dissolved organic matter; proxy more accurate than CDOM, colorful dissolved organic matter) (range 0 to 300 ppb QSU - Quinine Sulfate Equivalents, detection limit 0.07 ppb QSU, resolution 0.01 ppb QSU) : Dissolved organic matter / Dissolved organic molecule comes well from degradation of dead organisms, or from the excretion of living organisms (plankton).

- Optical DO, dissolved oxygen (range 0 to 50 mg / L, precision 0 to 20 mg / L ± 0.1 mg / L ie 0.1% of reading, and 20 to 50 mg / L ± 5% of reading, resolution 0.01 mg / L) : Dissolved oxygen (DO) is the amount of gaseous oxygen that is dissolved in the water. Free oxygen is essential for the life of fish, plants, algae, and other organisms; therefore, it has always been considered as an indicator of the ability of a river to support aquatic life.

- Turbidity (range 0 to 4000 FNU, precision 0-99 FNU with 0.3 FNU or ± 2% of reading, 1000 to 4000 NFU with ± 5% of reading, resolution 0-999 FNU = 0.01 NFU, 1000-4000 FNU = 0.1 FNU) : Turbidity is a measure of the degree to which water loses its transparency due to the presence of particles in suspension; Turbidity can impact aquatic ecosystems by affecting photosynthesis (limits the passage of sunlight), respiration and the reproduction of aquatic life.

How does 'My Buoy' work?

The catamaran pontoon (has two hulls) XYLEM is much more stable than a classic buoy in wind and hole conditions, quite frequent in Lake Titicaca. Even in these conditions, it allows working on board, programming, calibrating and repairing equipment. It houses 4 solar panels oriented in different positions capable of generating all the electrical energy necessary for the permanent operation of the equipment, as well as the Vaisala sonic weather station (without moving parts) at the top, and in the central compartment the vertical profiler (cable wrapped around a winch) to which the YSI EXO2 submersible multiparameter probe suspends.
The data generated by both sensor systems are stored in two Campbell CR1000 dataloggers (one for the multiparameter probe and the other for the meteo station), and transmitted wirelessly via the Internet via a Sierra Airlink modem . The data acquisition frequency as well as the vertical profiling frequency are fully programmable, with minimums of 5 min and 1 hour, respectively. The pontoon is equipped with a Garmin 16X-HVS GPS (high sensitivity, 12 channels, NMEA 0183 output) to detect a possible drift linked, for example, to the rupture of one of its two moorings, thus such as a radar screen and Carmanah M650 beacon for high-power LED lights with a 4-mile range to avoid nighttime collisions. Various software allow to synchronize the sensors among them and to program the emission of their data (LoggerNet), to program and analyze the profiled data (YSI Profile Wizard and custom written firmware CR1000 Turn Key System) and to generate automatic alerts in case of exceeding threshold values.