Work structure

4.3.1 The feasibility of the experiment at school: 4.3.1.1 Material and methods.

A course for middle school students was designed. The course aimed to make kids an active part in the conservation of local ecosystems, in line with the Italian school curriculum (Ministero della Pubblica Istruzione, 2007), that covers the protection of the environment among the subjects to be studied. The theme “Global climate change” is a topical and complex subject that offers the

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opportunity of developing cognitive skills in students such as grasping relations, collecting data, checking and processing results, using the appropriate language of mathematics / statistics.

The course for pupils of the third class of secondary school level, was divided into lectures in the classroom, to introduce the subject and build up the prerequisites, and experimental work. In the experiment, crustose coralline algae known as an indicator of environmental quality, were used to observe biological responses to environmental changes (Bradassi et al. 2010). Students observed spore production by L. incrustans under control and high CO2 conditions. A simplified protocol of Cumani

(2011) was adapted to the school laboratory.

Lectures: 16 lectures were held on diverse topics (the Gulf of Trieste; physics and chemistry of seawater; instruments and methods used in oceanography; reading charts of data; local coastal habitats; major local plant and animal; coralline algae, Global Climate Change: the IPCC notes; Ocean Acidification). Lessons were held outside school time, and were distributed throughout the school year. An inductive approach (bottom-up strategy) was adopted for teaching: - starting from the experimental data observed in the microcosm (aquarium) - matching the data with the knowledge gained in the marine environment of the Gulf of Trieste - via a modeling process capable of understanding the functioning of a complex system (Randler & Bogner, 2009), that is an ecosystem, and understanding the possible effects of global climate change on a local scale.

Laboratory: two 22 liter-aquariums (figure 2), equipped with a pump for water movement and chrono- regulated lighting (12 hours light and 12 hours of darkness); a system for the bubbling of carbon dioxide, regulated by a pH-meter connected to an electronvalve with negative feedback (Milwaukee); a bottle of carbon dioxide; a centigrade thermometer; microscopy slides; an optical microscope (KONUS); sea water. The temperature was not controlled (temperature of the room 21°C).

Figure 2: aquariums used at school (photo by F. Bradassi)

Experiment: Adult specimens of L. incrustans were collected by free diving to a depth of 3-4 meters at the seafront of the Trieste riviera, (45 ° 41 '21.79''N, 13 ° 44' 32.07 ''E). Samples were immediately brought to school, where the laboratory had been previously set up. In the first aquarium, (control)

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culture conditions were kept as similar as possible to natural ones. In the second aquarium, acidification was obtained by bubbling CO2 up to the preset value of pH (7.8). This value corresponds

to the value predicted by the end of the century by the IPCC (Parry et al., 2007) , the same proposed by Cumani (2011) in his experiments with L. incrustans. On reaching the pH target, the flow of CO2 was

interrupted by a negative feedback control obtained with the electron valve connected to the meter. The adult algae were treated following Cumani‟s protocol (2011), (smooth thermal shock; soft cleaning with a paint brush) and placed on 10 labeled microscopy slides in each aquarium. 48 hours after insemination, students took a census of the number of spores and young thalli present on each slide (figure 3), by direct counts under the optic microscope (Konus, 10X magnification). During the culture, physical-chemical data relevant to the growth of algae were regularly monitored, namely: pH, temperature, nitrites, nitrates, phosphates, hardness and the concentration of calcium and magnesium dissolved in water. The pH was monitored with a pH meter and with a test for aquaria, the temperature was measured with a thermometer and a thermocouple probe DB2 Texas Instruments, the chemical parameters (nitrites, nitrates, phosphates, hardness and the concentration of calcium and magnesium dissolved in water) were measured using specific tests for the aquarium (Red Sea Marine Aquarium Test). The data were collected and tabulated in tables with Windows Excel and plotted by graphs.

Figure 3: young thallus of L. incrustans Photo by F. Bradassi

The experiment was repeated twice during the year, in December 2009 and April 2010. Each cycle of experimentation lasted two weeks, during which the students were given the shift in the management of the laboratory. In the Lab, students worked in small groups of three at a time, for a total of 42 workshops of teaching units (to ensure that each student had at least six hours of actual laboratory).

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Peer education: The students who participated have, since then, involved classmates in their own experience, presenting them with the results they got (peer education). 4 hours were used in presentations.

A total of 52 hours of teaching was invested in the course. 4.3.1.2. Results

During both experiments, spores were produced in the aquariums. In December 2009, students counted 167 young thalli in the control aquarium and 60 in the acidic one. In April 2010, 1094 thalli were counted in the control tank and 217 in the acidic one. In both experiments, there was a reduction in the number of spores produced by individuals treated with CO2 with respect to the pool of control

(figure 4).

Figure 4: Results of censuses conducted by the students.

1 10 100 1000 10000

AUTUMN (December 2009) SPRINGTIME (April 2010)