Study of a natural ecosystem in the Delta Po Regional Park

Transcription

1 Study of a natural ecosystem in the Delta Po Regional Park Subject: Biology Grade level: Upper secondary Schools Anticipated time: 8 hours (lessons and outdoor activities) Developers: Institution: Country: L. Brancaleoni, O. De Curtis, U. Thun Hohenstein, M.C. Turrini Dipartimento di Biologia ed Evoluzione Ferrara University Italy

2 CENTRAL IDEA AND DRIVING QUESTION: What are the abiotic factors that allow the life in different environments? Which kind of animals and/or plants characterizes a specific ecosystem? Why biodiversity is a good indicator of the healthiness of an ecosystem? PEDAGOGICAL FRAMEWORK An ecosystem is a system with multiple layers and levels (e.g. abiotic and biotic factors). The availability of knowledge collected with technological devices allows a better understanding of the complexity of natural systems. Observation, measurement and identification of the main abiotical properties of an ecosystem (e.g. physical parameters) are essential to organize ecological knowledge and processes. Besides, an increasing level of responsibility for observational studies can be a teaching strategy (Hane, 2007). In last decades, a decline in biodiversity has been observed in many ecosystem of the world. Because biodiversity is the basis of the history of life on the Earth, its conservation is essential for the maintenance of natural systems. To preserve the biodiversity is essential to preserve the ecosystems Besides, ecosystem goods (ex. food) and functions represent "the benefits human populations derive, directly or indirectly, from ecosystem functions" (Costanza et al. 1997). Standard textbook definitions are mainly from Odum (1971, 1993) and Ricklefs (1983) who define an ecosystem as "the community and the non-living environment functioning together". In the Russian and German literature, an ecosystem is a "biogeocoenosis" (life and Earth functioning together). Mobile technologies can be used also to encourage students for an active learning. These experiences become collaborative because increase the flexibility and the opportunities for students interactions. In this way students work in teams and can compare their ideas. The teacher task is to guide and stimulate their observations. This module is thought as a starting point for the study of both the biotic and the abiotic factors of the observed ecosystem. For this reason the abiotic factors are measured by a set of sensors, while the biotic factors, that is macro animals and macro plants, are observed via their presence or the presence of their tracks. It can be a new tool to learn science in an interdisciplinary way. Life sciences are complex: in every moment biology includes chemistry, physics and all the scientific fields. The main abiotic and biotic factors sampled are: - Ions dissolved in the water: nitrates, chlorides and ammonium; - Salinity concentration in the water and soil; - O 2 dissolved in the water; - Water, air and soil temperature; - Water conductivity; - Soil humidity; - Plant, animal and track identification with the help of photos.

3 To record the collected data and to visualize immediately the sample points students have the chance of using a GIS installed on a LapTop, carried to the field. PREREQUISITE KNOWLEDGE: This module requires the basic knowledge of chemistry concepts and of the usefulness and use of a Geographical Information System CONTENT KNOWLEDGE In ecology, an ecosystem is a natural system composed by biotic and abiotic components: the biocoenosis and the biotope, respectively. The term was introduced in 1935 by A. Tansley and represents the fundamental unit of the ecological systems characterized by the interaction of the abiotic and biotic factors. With these interactions the ecosystem become dynamic, in continuous evolution thanks to the force of the energy of the sun. The main chemical-physical factors of the environment (abiotic, non-living) are: temperature, ph, mineral nutrients concentrations, light, oxygen and carbon dioxide availability. The biotic factors are represented by all the living organisms (microorganisms, plant, animal) that are continually engaged in a set of relationships with every other element constituting the environment in which they leave. The main parameters sampled in the module are as follow. The dissolved oxygen is one of the most important parameters to test the quality of the water of an ecosystem. The aquatic animals breathe the gaseous oxygen dissolved in the water and low levels of O 2 would bring to the death for suffocation (O 2 < 3 mg/l). The mains factors influencing the oxygen solubility are the temperature, the salinity, the photosynthesis and the bacterial activity. It is for this reason that, at our latitude, the most critical moments for the aquatic life are during the summer. The measure of the temperature of the water is important to investigate the thermal pollution because the speed of the chemical and biochemical reactions depends on it. Generally speaking, the water heating depends on the energy of the sun but other events, as waste water inlet, can contribute to the temperature increase. Besides, warm water contains less oxygen than the cold one because the oxygen solubility decreases with the temperature decrease. Concerning the soil and air temperatures, only few plants can manage a great difference between them, even if it is only for short periods during the year. Moreover if the temperature of the soil become too hot, its humidity decreases too much and plants or buried animals cannot live in that conditions. The water ph is the measure of its sour content and influences most of the chemical reactions and the quality of aquatic organisms living into it. The optimal range for these organisms is inclusive among 7 and 8.5 because different values can damaging the aquatic ecosystem. The salinity represents the impurity expressed for thousand parts of water (ppt). The mains elements that contribute to the salinity are sodium and chlorine, the normal components of the salt used in the kitchen (NaCl). In the salt marshes, there is a large range of salinity because the fresh water of the rivers mix with the sea water. Therefore, the salinity of these brackish waters register values among that of the fresh waters (in average ca. 0.5 ppts) and that of the sea water (35 ppts). Besides the chlorides, the mains ions dissolved in the water are ammonium and nitrates. In the water nitrogen can be in various forms: molecular nitrogen (N 2 ),

4 organic nitrogen, ammonium (NH + 4, in equilibrium with the ammonia related to the ph value), nitrite ion (NO -- 2 ) and mostly ion nitrate (NO - 3 ). Generally, he NO -- 2, is present only waters with poor dissolved oxygen. The nitric nitrogen can arrive from the atmosphere as rain, snow or fog, from the decomposition of the organic materials, from farming and fields fertilizations, and from waste water. A low content of nitrogen in plants can be a limiting factor but an excessive content can leading to an excess development of algae causing the eutrophication process. The result is an increase in the ecosystem's primary productivity with further impact including lack of oxygen and severe reductions in water quality and in fish and other animal populations. Nitrates founded in the water represent the last oxidative stadium of the nitrogen cycle for the break down of the organic compounds (proteins). Micro-organisms present in the soil and in the water, produces at first ammonium and subsequently there is an oxidation of ammonium to nitrates. Besides, for the waters the greater sources of nitrates are represented from the urban pollution, from waste water, from farming and from exhaust gas. The nitrates represent a danger for the human life only if transformed in nitrose nitrogen. The ammonia is present in the water for the biological degradation of the proteins but, obviously, also for the industrial pollution. Its presence, also in traces, is often index of recent organic pollution. The Electrical conductivity is a measure of a material's ability to conduct an electric current. It s a good indicator of impurity: the value is greater when the impurities increase. MATERIALS For this module you will need: - LabQuest datalogger - LapTop or PalmHandeld - GPS - Nitrate, Chlorure and Ammonium sensors - Salinity sensor - Dissolved O 2 sensor - Temperature sensor for air, water and soil - ph sensor - Box for samples of waters - Digital camera - conductivimeter - GIS software - Level, stadia rool and metric tape (for the second ecosystem) CONTEXT We propose the study of aquatic and terrestrial ecosystems. Aquatic ecosystems can be salt marshes, saltworks, river, lake or swamp; all the aquatic ecosystems are

5 indicated. Terrestrial ecosystems can be coastal sand dunes, which are common in different parts of the world. For this experiment we propose salt marches, saltworks and dunes of the Delta Po Regional Park (Italy). The Park covers a very important part of the territory of the Emilia-Romagna Region: starting from the Po di Goro river, that is the southern branch of the Delta at North, it develops to South including the whole historical delta of the Po river and the mouths of some Apennine rivers. It is also characterized by brackish wetlands situated along the Adriatic coast, by inner wetlands, woods and pinewoods. It is also rich in many important monuments like abbeys, monumental water locks and historical towns. In the Po Delta Park of the module can be experimented in the saltworks of Comacchio, the largest complex of brackish wetlands of the Emilia-Romagna (N-E Italy). The Comacchio saltworks extends for about 600 hectares and is situated in the East part of the Salt Marshes of Comacchio (Ferrara Province). The saltworks is constituted by a system of rectangular basins divided in first, second and third evaporation basins for the salt concentration and a last basin where the salt is formed and harvested. Therefore the parameters measured have different values inside these evaporation basins. Salt marshes and saltworks are peculiar ecosystems characterised by salty water. In these ecosystems, the existence and development of life depend both from quality and quantity of water, and salt concentration. These areas are protected for their elevated environmental and naturalistic importance, very useful as an outdoor class for studying the natural sciences. The saltworks ecosystem is characterized by different microhabitats like channels for the sea water entrance and exit, water basins at different depth, evaporation basins for the salt harvest. All these microhabitats will allow to analyse waters with different chemical-physics parameters and to understand how small variations of the water parameters influence the life of the plants and the animals (birds in particular) that live around the basins or on the rises emerging from the water. The typical vegetation of this environment is characterised by the presence of the halophytes, plants which tolerate or even demand different sodium chloride concentrations. In turn these plants host the nests of the aquatic birds that live in this ecosystem. In the Po Delta Park the module can be experimented also in the coastal sand dunes, a kind of environment today very rare, because completely untouched by human activities, especially the tourism industry. One of the remains of this wild environment is at the mouth of Bevano river, which is an Apennine river. That important area testimonies, with his natural dunes and coastal lagoons behind the dunes, as should be the entire coastline of Emilia Romagna Region before the first massive human interventions. The area is an important place for many species of migratory birds, including several wading birds. Dune systems are very fragile habitats that grow as sand is captured and held in place by plants such as beachgrass and beach pea. Coastal sand dunes constitute a variety of microenvironments due to substrate mobility and physical processes. These microenvironments are: embryo dune, foredune, dune slack, mature dune and scrub. All of these are present only if the evolution of the beach and dunes is completely natural; where men worked over the nature, some of these environments lack or they are overlapped. Plants establishing on coastal sand dunes are subjected to several environmental fluctuations which affect their growth, survival and community structure. The most important factors include temperature, desiccation, low moisture

6 retention, soil erosion, sand accretion, soil salinity, salt spray, changes in organic matter and ph (Arun et al., 2008). INSTRUCTIONAL ACTIVITIES Lesson 1: In (Preparatory) Duration: 3 hours Goals: The students acquire basic knowledge about the heritage site and the parameters they will measures in the field and take confidence with the GIS functions they will use during the outdoor lesson. In the classroom teacher illustrates the principal parameters of the water, soil and air, that the students will measure and introduces them in the use of LabQuest datalogger and environmental sensors. Moreover students take confidence with GIS in order to insert points by GPS coordinates in a georeferred map already loaded, create and fill in an attribute table referred to the point. Teacher illustrates the characteristics of the chosen area: flora, fauna, geological and geomorphologic features, also by means of a video-tape or a dvd and/or by researches in internet (website of the Park, if it exists). Lesson 2: Out (of the Classroom) Duration: 3 hours Goals: The students collect the data required about the abiotic and biotic factors of the chosen ecosystem and based on that, their curiosity will be stimulate; moreover they will improve their ability of working in group. If the module takes place in a protected area the teacher must ask the income permission and/or the permission to pick up the samples. Procedure: On the field, as first step the teacher recall the general information of the area she/he has spoken about in the preparatory lesson. In order to collect the data, students are divided in small groups. Every group will deal with some aspects of the study. For every sampled point in each basin, students record the geographical coordinates with the GPS and store them in GIS draw of the georeferred saltworks map. Then they analyze the quality of the water with the different sensors connected to the datalogger: ions concentration (ammonium, nitrates, chlorides), salinity, oxygen dissolved in the water, temperature, ph, conductivity and temperature. For every point students take 2-3 measures of the chosen parameter to verify the rightness of the values and fill in the table with the average. All the data will be recorded automatically in the datalogger and immediately visualized as graphs. Sampled waters are eventually picked up for the analysis in laboratory with the microscope to see the aquatic microorganisms. Furthermore students have to collect data for the temperature and humidity of the air and temperature, humidity and salinity of the soil, using the same modality as for the water. After physical data are taken and recorded, instructor will lead students in a brief discussion and analysis of the data collected.

7 At the same time other students record the presence of plants and animals, comparing what they see to some pictures of principal distinctive flora and fauna stored on the GIS saltworks map, and observe their behaviour and/or healthiness. While this task is carried on, students are requested by the teacher to discuss briefly what they see about quantity and conditions of different species. In case the teacher decides to test the module in the coastal dunes, the only difference is that the observations and the collection of the data are made along a line crossing all the dune, from the surf area till the backdune. First of all the dune's relief has to be constructed using the level, the stadia and the metric tape. The measures of physical parameters and the observations on plants and animals are made referring to the different microenvironments of the dune. Lesson 3: In (Follow up) Duration: 2 hours Goals: Interpretation of the collected data to understand the central idea of the module and answer the driving questions Into the classroom every group of students presents what they have measured and observed. All collected data are downloaded in the computer connected with the projector ant the teacher shows the graphs of the same physical parameters, collected in the past by the park organisation, if they exist. Students are stimulate to formulate some hypothesis to explain the variations, if they are, or the continuity of the data. The distribution of the flora and fauna and the variation of the physical parameters from one basin to another one is clearly visible with a simple elaboration of the data by GIS. The so obtained saltworks map is the starting point for a more deep discussion and analysis. In the case of the coastal dunes, the follow up duration is 1 hour more long. The students used the level, first of all they have to reconstruct the dune relief, then they have to create the GIS map and the attribute tables associated to the microenvironments of the dune. Objectives: At the end of the module students will know: - The structure and composition of an ecosystem - The evolution of microhabitats - The influence of the climate on ecosystems - The relationship between the abiotic and biotic components of an ecosystem Students will learn how to use Palm Handheld Computers and environmental sensors to collect data in the field Students will take confidence with GIS technology Students will realise that biology is a multidisciplinary science always linked to the other scientific areas (chemistry, physics, geography, mathematics and geology).

8 EXSTENSION It is also possible to experiment the module in seasons well diversified for temperature and precipitation (e.g. summer and winter) to understand also the decisive role of the climate on the life of the ecosystems. Water samples are taken to visualize at the microscope the content of microalgae and aquatic microorganisms. Students can discuss about further methods and applications regarding the study of an aquatic ecosystem and discuss about applications the man's role on the quality of an ecosystem. Compare the characteristics of different ecosystems (aquatic and terrestrial). ASSESSMENT In small groups, students will present their work to the class in order to demonstrate: - Their ability to use datalogger and sensors; - Their ability to use GIS; - The complex interactions between plants and soil. To check the individual preparation the teacher can: - Ask the graphs interpretation; - Stimulate hypothesis on the possible trend of the graph under different conditions of the weather (e.g. a different season); - Make a final test. BIBLIOGRAPHY Arun A.B., Beena K.R., Raviraja N.S., Sridhar K.R., 2008 Department of Biosciences, Mangalore University, Mangalagangotri, Mangalore , India; Costanza, R. et al The value of the world's ecosystem services and natural capital. Nature 387: Hane E.N., Use of an inquiry-based approach to teaching experimental design concepts in a general ecology course. Teaching Issues and Experiments in Ecology 5: Odum, E Fundamentals of Ecology. Saunders. Odum, E Ecology and our endangered life-support systems. Sinauer. Ricklefs, R The economy of nature. Chiron Press.