DNL SVT

School years 2016-2018

The automatic watering can

The last year the students decided to realize an automatic watering can for houseplants owners who need to keep their plants safe when they go on holiday.

The students studied the needs of the most common houseplants. They imagined the design, the material, the sensors and the program for their watering can.

They decided to program it on a Raspberry Pi motherboard, a tiny and affordable computer. We wish to thank Mr Grandjean, a engineering sciences teacher who helped us for the understanding of Raspberry Pi.  

The design phase has been achieved but the students did not write the program this year.  

Miss URITY O, biology and geology teacher for the European Class.

Design realized by Lindsey Desirliste

Design concept made by Lindsey Desirliste

School year: 2018-2019

 


 Biodiversity of the  mangrove of Genipa Bay

 
   
 
   

Click on the video to see the mangrove tour

In the mangrove swamp of Genipa Bay, we were able to be in touch with a very diversified biodiversity.

Let’s see it closer:

The mangrove swamp is the link between the land and the sea. It grows in a brackish environment that is a mixture of fresh water and salty water. It is inhabited by a very rich and varied flora.A little more towards the sea, recovering the waterbottom, we find the seagrass bed. It consists of a variety of plants mostly Thalassia testudinum (Hydrochoritaceae) also called “Turtle grass”. We find some algae species such as Caulerpa taxifolia (Caulerpaceae) an invasive specie originated from the Indian Ocean.

Seagrass bed from the bridge of the Pottery Village, Photo by O.URITY

 

 
 

Jellyfish Cassiopea Andromeda and Thalassia testudinum (the green leaves) on the sea bottom, at les Trois Ilets Pottery, photo by N. Lecerf

 

 

In sea front, we find the red mangrove tree. It is a characteristic tree of the mangrove swamp. It adapted itself to its environment thanks to its stilt-roots, which allow it to stay stable on the muddy ground of the mangrove swamp mainly consisted of vase. They also allow it to move forward on the sea and to face waves. The lenticels, small pores, allow it « to breathe » in a muddy and low-oxygen ground. These leaves are thick because of in the salinity of the water. Moreover they have salt glands which release the salt outside the leaves.

Stilt- roots of the Rhirophora mangle (Rhizophoraceae), photo by Christale Crouard

A little more out-of-the-way on lands, we find the black mangrove trees (Avicennia vitida , Verbenaceae). We can also find it in cohabitation with the red mangrove tree. It is easily recognizable thanks to its pneumatophores, outgrowths air of the roots to breathe. These sheets also are thick, for the same reason that the red mangrove tree.

Pneumatophores in the muddy ground.

 Lenticels on the red mangrove tree roots.

Source : www2.palomar.edu

Finally, between the mangrove swamp and the ground, we find the white mangrove trees (Avicennia germinans, Verbenacea) and the grey mangrove trees (Conocarpus erectus, Combretaceae). During our visit we didn’t see these two last species.

The mangrove swamp establishes the completed refuge for numerous species. It is an area of breeding, passage for migratory birds and food.

In the mangrove swamp itself we saw different species of animals and plants:

Aratus pisonii a crab specie which lives on the stilt-roots, photo by Christale Crouard

Green Heron , Butorides virescens also called “kayali” in creole speaking language

Ardea alba ,the Great Heron a migratory bird

An unknown spider specie, photo by Crouard Christale

 

Source: https://pixabay.com

 

Mongoose specie (Viverridaea)

Common moorhen (Gallinula chloropus, Rallideae)

 

Water hyacinth (Eichhornia crassipens, Pontederiaceae) an invasive plant which colonized the “Rivière-Salée”.

Source: https://pixabay.com

 

Author : CROUARD Christale

Lay-out : Loustalet Clara, Boniteau Guillaume, Miss URITY

Appreciations to:  Nicolas Lecerf for his help

Correction : Miss URITY and Miss Marie-Luce




Physico-chemical measurements in the mangrove

 

Some students have made measurements in the sea water so we were able to  study  some physico-chemicals characteristics of the mangrove.

-Water conductivity: It is defined as the ability of a substance to conduct electricity. It can give an idea of the amount of ions found in the liquid.

Stephan during the recording of water conductivity, photo by M.KNIFIC

pH:

The pH is a measure of hydrogen ions concentration. It allows to determine the acidity and the alkalinity of a solution. It’s expressed as a number on a scale on which a value of 7 represents neutrality and lower numbers indicate increasing acidity and higher numbers increasing alkalinity.

Lucas doing a pH measurement, photo by K.Morin

Temperature

A measure of the warmth or coldness of an object or substance with reference to some standard value. The temperature of two systems is the same when the systems are in thermal equilibrium

Guillaume recording the temperature, photo by K .Morin

Water samples    

We took several samples of water in order to analyze them in class and determine the salinity in different sites of the Genipa Bay and the Rivière-Salée.

Authors : Knific Matteo and Morin Kelian

Lay-out : Loustalet Clara, Boniteau Guillaume, Miss Urity

Correction : Miss Urity and Miss Marie-Luce


Determining the salinity of the water samples

We have taken samples of water at different places in the mangrove. Then we brought them back to school where we realized salinity tests with each sample.

The salinity is the quantity of dissolved salt in the water. We can find different ions in the water : sodium, chloride, magnesium, sulfate, potassium, nitrate and sodium bicarbonate. The most important ions are chloride and sodium; the others are in negligible amounts so the value of salinity is not so far different from the value of the concentration of the chloride and sodium ions.

We used titration with silver nitrate to determine the concentration of chloride ions in order to get the chlorinity of our samples.

Hands-on in biology class.

Source: France-antilles

We have considered that the chlorinity was close to the value of the salinity as that ion and the sodium are the major ions in concentration in the sea water. By the way the concentration of sodium is equal to the concentration of chlorine.

So we didn’t take into account the other ions in our experiment.

We measure a solution of chloride ions Cl- of molar concentration C1 by using a solution of ions Ag + of molar concentration C2 known, in the presence of a solution of neutral chromate of potassium serving as indicator of the end of reaction.

The steps were :

  • Take 5 ml of your sample and put it into a beaker.
  • Fill the buret with the silver nitrate solution. (use the instructions for use)
  • If the buret is ready (no air bubbles, no leaks) : take an initial volume reading.
  • Deliver the silver nitrate solution until the appearance of the red color.
  • At that point take the volume of delivered silver nitrate.
Number of the sample Location : GPS point V(Ag+) E (ml) C (Cl-) mol.l-1 SALINITY (g.l-1)
1 Latitude : 14° 32 .265’N

Longitude :   61°0 .743’W

Pottery mangrove

31 0,62 22,01
2 Latitude : 14°33.072N

Longitude 60°59.888 W

Rivière-Salée

Entrance of the mangrove

25 0,5 17,75
3 Latitude : 14°32.795N

Longitude :   60°59.525W

Rivière-Salée

1,2 0,024 0,852
4 Latitude : 14°32.729 N

Longitude :   60°59.502 W

Rivière-Salée 30 meters before the RN5

0,2 0,04 1,42
5 Latitude  : 14°33.017N

Longitude 61°0.220W

Open ocean, close to the « Petit Piton » Islet

40 0,8 28,4

Table with the results of our experiment

To conclude we can say that the salinity changed according to the places where the sample had been taken. The salinity increases when we go from the Riviere-Salée to the « Pottery ». We can deduce that the Rivière-Salée is composed of fresh water and that the mangrove has brackish water with a salinity situated between the salinity of seawater and fresh water (Samples number 1 and 2).

We will take other samples in Lousiana (bayou and swamp) in order to compare the salinity of theses ecosystems with the salinity of the mangrove.

Authors : Lacroix Elisa, Miss Urity

Correction : Miss Urity and Miss Marie-Luce


Natural and human threats on the mangrove

Mangroves are one of the most productive and richest ecosystems in the world, but also the most endangered.

In fact, they are threatened by several human activities such as  :

  • Urbanism and port infrastructures: the construction of roads and infrastructures is responsible for deforestation and cause the disappearance of mangroves.
  • Overexploitation of wildlife causes a reduction in the amount of young fishes that grow in the mangrove, this would cause an imbalance in the food chain of the mangrove.
  • Industrial and domestic pollution such as wastes and wastewater discharged into nearby mangrove ecosystems such as rivers, marshes and rivers. They can eventually reach the mangrove due to currents and tides. Rejected directly into the mangroves, they induce as many problems and bad odors, degradation of water quality by wastewater loaded with various chemicals from domestic and industrial activities
  • Climate change : It is now a certainty that storm events are more frequent on a global scale, as the level of water and ocean surface temperature increase due to global climate change.The impact of these events on marine levels could threaten the long-term survival of mangroves.

 

Conceptual framework : Principal impacting factors of climate change and how they are likely to negatively influence mangrove communities

 
 Source : http://onlinelibrary.wiley.com  

Authors : Solitude Valentin,

Lay-out : Loustalet Clara, Boniteau Guillaume, Miss Urity

Correction : Miss Urity, Miss Marie-Luce


Click on the video above to see the bayou

During our trip in Louisiana we visited the swamp and the bayou at Jean Lafitte National Historical park and Preserve, Lafayette.

Due to the presence of Alligators, the guide Jason, tooks the samples of water for us.

Then, during a biology class session in St Martin Episcopal Church, we used a refractometer to determine the salinity of the water of these 3 ecosystems : the canal, the swamp and the bayou.

The results are presented in the following table.

Samples GPS points Salinity g.l-1 pH
Sample 1 : canal Latitude : 29° 46 .973N

Longitude : 90°5.663 W

0 6,12
Sample 2 : swamp Latitude : 29°47.079N

Longitude

90°5.174W

0 6,20
Sample 3 : bayou Latitude :

29°47.052N

Longitude :

90°4.680W

0 6,31
Reference test:

  35 5,46
     

To conclude, the bayou and the swamp are composed of fresh water. Even if they share some physico-chemical characteristics and some living beings adaptations with the mangrove the salinity is very different.

Authors: Joseph-Julien Anaëlle, Crouard Christale, Urity Olivia

Video editing : Crouard Christale

Appreciation to : Perro Philippe for his help, Miss Stacy Richards from St Martin Episcopal School from Metairie, Louisiana


     Biodiversity of the wetlands of Louisiana

The tree species

The Bold Cypress  (Taxodium destichum)  and the Spanish Moss ( Tillandsia usneoides)

The Tillandsia usneoides or Spanish moss (mousse espagnole ) was used by the doctors to sew up people.

The Red Maple (Acer rubrum)

The American Dwarf Palm (Chamaeops humilis)

The Water Hyacinth (Ecchornia crassipens)

The hand prosthesis

During the second part of the year the students decided to build a hand prosthesis for our lab skeleton named Alphonse.

First of all the students had to understand the biological functioning of a hand. So we studied the mecanisms which allow the brain, nerves, muscles and tendons to move the different fngers of the hand.

Then we worked on the design and the material that we were  going to use in order to realize the prosthesis.

Then we worked on the design and the material that we were  going to use in order to realize the prosthesis. We chose to build it with the 3D printer located in the engineering lab of the high school.

Mr Perro, an engineering sciences teacher helped us for the choice of the program and the motherboard used to move the prosthesis. So it has been programmed with the Arduino software.

The Following video shows the glove , cables, motor  and sensors used to move the 3D printed hand.

Watch and enjoy!

Miss URITY , Biology and Geology teacher for the European Class

The hand prosthesis concept made by Naullet Arthur,  Annette Léo and Crouard Chrystale