مقالات علمی شیلات و علوم دریایی
Phytoplankton:Plants of the Sea
by Prentice K. Stout
To the casual observer, the oceans and bays are vast trackless bodies of water. Beneath their surfaces are countless fish. But more numerous by far are the tiny microscopic animals and plants collectively called plankton, a word derived from the Greek meaning wandering.
The plant portion of this complex oceanic soup is called phytoplankton. The term phyto comes from the Latin phyton meaning tree or plant. This large grouping is composed mostly of single-celled algae and bacteria.
It is known that green plants liberate oxygen and produce carbohydrates, a basic link in the food chain of plants to animals to people. Collectively, this chemical process is referred to as photosynthesis (photo = light, synthesis = to make). In these tiny food factories, there is a chemical compound called chlorophyll that, in combination with sunlight, converts carbon dioxide, water, and minerals into edible carbohydrates, proteins, and fats. Thus, these phytoplankton are the basis for the oceanic food chain. Animals cannot perform this biological food-making process. Two-thirds of all the photosynthesis that takes place on this earth occurs in the oceans that yearly create 80 to 160 billion tons of carbohydrates. So numerous are these tiny plant forms that they often turn the water green, brown, or reddish.
Among the most abundant phytoplankton are the diatoms. Some 20,000 species make up this plant group. They consist of a tiny blob of protoplasm enclosed in a transparent pill-box structure made of silica. This silica, the main ingredient of glass, is extracted from the surrounding seawater. Minute holes or pores in their shells permit nutrient absorption and an exchange of carbon dioxide and oxygen to take place with the surrounding seawater. Under favorable conditions, a single diatom can reproduce 100 million offspring in a month. Clearly, such reproductive capacity creates vast numbers - as many as a billion of them in a gallon of seawater. Those that are not eaten die and their virtually indestructible shells settle to the bottom of the ocean. In some areas of the sea, their skeletal remains form layers up to 700-feet thick. This diatomaceous earth has been used as a fine abrasive in toothpaste and automobile polish. A drop of oil within the protoplasm in the shell may have created the earth's petroleum supply. This oil in the diatom is eaten by a number of small fish; one is called the capelin, which, in turn, are eaten by codfish. From the codfish bodies come cod liver oil detested by some, but rich in vitamins A and D.
While diatoms are essentially cool water inhabitants, their counterparts in tropical waters are called dinoflagellates. Equipped with whip-like projections, they propel themselves about in a jerky motion.
Dr. C.P. Idyll, noted oceanographer, states, "The various species of dinoflagellates resemble chinese hats, carnival masks, children's tops, urns, pots, and vessels of many kinds, the spiky knobs of medieval war clubs, balloons on strings, hand grenades or lances."
Flagellates, like diatoms, are proficient in their ability to reproduce. By splitting in half, a dinoflagellate can reproduce thirty-three million offspring in only twenty-five divisions. One species of dinoflagellate, Gonyaulax, whose excessive reproductive ability can create havoc, produces the "red tide." In the seventh chapter of the Book of Exodus, the people of Egypt were plagued with what could have been an outbreak of the red tide. Charles Darwin, on his around the world voyage on the Beagle, wrote one of the first scientific accounts of a dinoflagellate outbreak that discolored the waters off Chile.
Another interesting dinoflagellate, if disturbed, emits light in the form of bioluminescence. Called Noctiluca, this small organism combines two chemicals, luciferin and luciferase (Latin: lucifer = "bearer of light"). This is the same combination of chemicals that gives our familiar firefly its ability to blink during warm summer evenings.
A simple tool can be used to study these plant forms. One needs a coat hanger that has been worked into a circle. Then over this frame stretch a pair of discarded pantyhose. Cut off the legs of these stockings just below the knee and place a small plastic pill jar in the openings. Tightly wind some thread around the fabric and the mouth of the jars and then tow it through the water. The fine mesh stocking of the pantyhose will capture may of these small plant forms as well as their animal counterparts. (See fact sheet on zooplankton.) A hand lens or microscope will assist in the viewing of these fascinating organisms.
Buschbaum, Ralph and Milne, Lorus J. 1960. The Lower Animals, Doubleday and Co. New York.
Silverberg, Robert. 1972. The World Beneath the Ocean Wave. Weybright and Talley, New York.
Fun with Phytoplankton
Return to Rhode Island Sea Grant Fact Sheets
گیاهان موجود در دریا
طبق بررسی های انجام شده منطقه وسیعی از آب اقیانوسها و خلیجها هستند.درسطحهای آنها ماهی های بیشمار است اما در قسمتهای زیر حیوانات میکروسکوپی ریزی هستند و انبوه گیاهان که به آنها پلانگتون می گویند .
یک کلمه ای است که از معنی یونانی مشتق شده است بخش گیاهی آن که در اقیانوسهاست فیتوپلانگتون نامیده می شود کلمه فیتو ازکلمه لاتین فیتون یعنی درخت یا گیاه گرفته شده است .
این گروه بندی عمدتا جلبکهای تک سلولی و باکتری هاست .آنها فهمیدند که گیاهان سبز اکسیژن آزاد می کنند و کربوهیدراتها ( ماده قندی تولید می کنند ) و یک حلقه زنجیره اصلی در زنجیره غذایی از گیاهان به حیوانات و به مردم تشکیل می شود .مجتمعا یک فرایند شیمیایی اشاره شده به فتوسنتز ( گیاه = نور و سنتز = ساختن )
در کارخانه های غذا ریز یک ترکیب شیمیایی است که به آن کلروفیل می گویند در ترکیب با نور آفتاب به گازکربنیک و آب و کانی ها به سوی مصرف کربوهیدرات ها و پروتئین و چربی تبدیل می شود .بدین ترتیب فیتوپلانگتونها اساس زنجیره غذایی اقیانوسها هستند .حیوانات نمی توانند فرایند ساختن غذایی را از لحاظ زیست شناختی انجام دهند .
دو سوم تمام فرایندهای فتوسنتز گیاهان در روی زمین تشکیل می شود ودر اقیانوسها سالانه 80 درصد به 160 تن کربوهیدرات تشکیل می شود .که گیاهان ریز به رنگهای سبز و قهوه ای یا مایل به قرمز تاسیس می کنند .بین فراوانترین فیتوپلانگتونها دیاتومها هستند .مقدار 20000 هزار گونه از این گروه گیاهی ساخته شده است .آنها شامل قطره های ریز پروتوپلاسم می باشند. که در یک ساختار محفظه قرص شفاف از سیلیکا ساخت .این سیلیکاها جزء اصلی شیشه هستند که استخراج شده از محوطه محصور آب دریا یا منفذهایی در پوسته هایشان است که جذب مواد غذایی صورت می گیرد و تبادل گازکربنیک صورت می گیرد .
و اکسیژن که تشکیل می شود با محوطه محصور آب دریا زیر شرایط مطلوب با دیاتومها می توانند در یک ماه 100000 فرزند تولید کنند .به وضوح چنان ظرفیت زایش شماره های وسیع به تعدادی که یک بیلیون از آنها در گالن از آب دریا ایجاد می کند .مرده های آنها خورده نمی شوند و پوسته های ویران شدنی آنها در بستر اقیانوس ساکن می شوند .
در مناطقی از سطح دریا اسکلتهای باقی مانده ی آنها به لایه های ضخیم 700 تشکیل شده است .
سیلیسهای زمینی به عنوان ماده ساینده خوب در خمیردندان و واکس اتوموبیل به کار برده می شوند .
یک افت روغن در داخل پروتوپلاسم در پوست ممکن است عرضه نفت خام زمین را ایجاد کند این روغن در دیاتومها توسط تعدادی ماهی کوچک خورده شده است .ماهی های کوچک مثل کاپیلین در نوبت هستند توسط ماهی روغن خورده شده اند .از بدنه های ماهی روغن به دست می آورند که غنی از ویتامین a,d است .
زمانی که دیاتومها درآب خنک ساکن هستند و همتاهایشان در آبهای گرمسیری هستند به آنها دیفوفلاژلها می گویند آنها خودشان را راجع به یک جنبش پر تکان می دادند.
دکتر c.p.idyll یادداشتهای اقیانوس شناسی ایالت را به دست آورد .گونه های گوناگون دیفوفلاژلها شبیه به کلاههای چینی بود که کارناوال را می پوشاند و شبیه خاکستردانها و تکه ها و آوند ها نوعهای زیادی است .
درختهای خاردار که برای جنگ به کار می رود و بادکنکهایی در الیاف گیاهان است که به صورت نارنجکی و نیزه است .تاژکداران ودیاتومها را دوست دارند و ماهر هستند در توانایشان که دوباره تولید کنند .به علت شکاف خوردگی در یک دیفوفلاژلها می توانند تولید کنند تنها 3 میلیون فرزند در بیست و پنج بخش .یک گونه ازدیفوفلاژلها توانایی زایشی بیش از حد می تواندخسارت هایی ایجاد بکند.
درفصل هفتم کتاب exodus مردم مصر آفت راباشیوع ناگهانی درجذر ومد پیدا کردند.
چارلز داروین:یکی از روش های حساب های علمی باشیوع ناگهانی دیفوفلاژل درآب شیلی نوشته است.
دیفوفلاژل جالب دیگری که اگر مزاحم نشود . روشی در شکل تولیدات نوری از خود بیرون می دهد که به آنها تاژکداران گفته می شود که این ارگانیسم کوچک به دو ماده شیمیایی ترکیب می کند.این همان ترکیب ماده شیمیایی است که کرم شب تاب درطی عصرهای گرم تابستان رخ می دهد پس برروی این جوراب شلواری شاسی کش دور انداخته می شود.
هم اکنون دررنگ اثر باد برروی زانوهاومکا ن یک کوزه قرص پلاستیک کوچک در دهانه ها است .تنگ باد مقدار نخ اطراف ساختار ودهانه کوزه ها وسپس توز کشی آ ن توسط آب صورت می گیرد .
Testing two water bodies for pollution
Two water bodies of the same water catchment are going to be investigated, to look for and compare any pollution that may be present. They have to be in the same water catchment because this will ensure that they both get the same rainfall. If they didn't, it would affect the results, e.g. if slightly acidic rain fell into one of the two, and not in the other, this wouldn't be fair. So by using two in the same water basin, the results should be as accurate as possible.
Downs Banks Stream is a tributary to the River Trent, and is found within a national park, where the general public are not allowed to pollute it directly. This means that it shouldn't have any pollutants that would be present if the public were allowed access to drop litter, dump waste, etc, to pollute it. Also this stream is used by the local water authority to compare pollution levels around the area with, this is due to the fact that this stream is one of the most unpolluted water bodies around the area \ will provide accurate results to compare others to.
Yet it is believed that the river Trent at Stone, is significantly polluted. There are many factors which provoke this belief, one is that it is down stream from a major industrial town- Stone, this provides alot of sources of pollution: public dumping their wastes, rusty car parts have also been found in the spot to be investigated.
Also, because the river is down stream from an industrial town, this means that there will be the hot water spilling out from factories, etc, these would be point sources, which reduces O2levels \ killing off aquatic life. Moreover, there is a sewage works up stream, which when there are bad storms, has overspills of untreated waste into the river. This means that aswell as raw sewage, there are also the effluents and chemicals that get into the sewage works, these will all contribute to the polluting of the river and aquatic life.
Also pollution from landfill sites in the area can get into ground water and filtrate into the surrounding rivers, river Trent included. Aswell as land fills; there are still the old mineshafts, which are on route to the spot to be investigated on the Trent. Some of these mineshafts have become flooded with ground water and if the water happens to be polluted by anything and it could seep into the rivers. These wouldn't be point sources because determining where the pollution originated would be difficult.
The Trent is also far down stream from farmland which could be treated with chemicals such as nitrates and phosphates. Overuse of these chemicals means excess, which when it rains, can get washed directly into the river, or into tributaries, and eutrophication can set in: These excess nitrates can then cause the aquatic plants to overgrow, become crowded and die off. Bacteria then thrives growing in population and using up all the oxygen, which then affects the other aquatic life which too die off.
Large white tray (white so show up the organisms)
specimen tray (to look closer at the different species)
pH testing kit
nitrate testing kit
dissolved oxygen testing kit
Trent biotic index
To investigate pollution levels of both the water bodies, four tests are going to be carried out: pH test- approx 10ml of the water that is to be tested in put in a small container and a tablet (that is crunched up) is added, this solution is put in a little box and looking through the box, the colour is compared to other colours on the box. Whichever one matches, that is the pH. The pH is going to be investigated to see if there are any impurities in the water, that may have an acidic or alkaline origin. Although, it is known that water found in rivers is naturally acidic because of the pollution in our atmosphere, some becomes dissolved in the rain clouds and rains down slightly acidic. Also when aquatic organisms die, the amino acids in their bodies disperse in the water too.
A nitrate test is going to be carried out to find out if there are too many nitrates- parts/million, if there is it could lead to eutrophication. Naturally, there are going to be some levels of nitrates in the water because of nitrogen from decaying organisms and nitrates in excretion that could get into water bodies, etc:
The tube will be rinsed with the water to be tested to dispose of any impurities. This will then be filled with 10ml of the water to be tested. Next add, using the clippers, the contents of the little sachet- Nitraver 5 nitrate reagent powder to the solution- BE VERY CAREFUL BECAUSE THE NITRATE SUBSTANCE IS CARCINOGENIC- and shake for one minute to mix it with the water. Take the solution and compare it with a resin block, which will show what levels of nitrates match up with which colour.
Also an oxygen test will be carried out to see how much dissolved oxygen there is in the water- parts/million. This will be done by carrying out the following process:
Rinse the glass stopper bottle 3 times and fill up to the neck with the water to be tested.
Add 5 drops of manganous sulphate and shake. CAREFUL CHEMICAL CAN BE HARMFUL.
Add 5 drops of sodium hydroxide, potassium iodide, and sodium aride solution and shake. CAREFUL CHEMICALS CAN BE TOXIC, IRRITANT AND CORROSIVE.
Place some of the sol into the plastic container up to 5ml.
Add 10 drops of 42% sulphuric acid and shake. CORROSIVE.
Add 1 drop of starch , salicylic acid solution till the colour turns dark. IRRITANT.
Add 1 drop of sodium thiosulphate till the solution turns back to the original colour and this will be taken as the end point. By counting how many drops it took to turn the colour back, use this figure, multiply it by 10 and this gives the dissolved oxygen content in mg/l (parts/million).
The Trent biotic index was also used to determine how polluted the two water bodies were. This contains different species of aquatic life, not including plants, which are found in certain conditions and levels of pollution because some can withstand a little pollution, yet some can't, etc. This test will be done by carrying out several kick tests per water body, these will be done by: taking a large tray and a specimen tray, and filling them with the water being tested
wash the net out first to get rid of anything that may still be on it from previous investigations placing a net in the opposite way to the direction that the water is flowing, stand facing the net and start to kick around the bottom side to side,
whilst doing this move up stream as to gather more of wha Color t is going into the net,
after approx 30 seconds stop and empty the contents of the net into the large tray making sure that everything has been taken out.The various organisms that have been collected can then be looked at closely. Afterwards, they will be put into the specimen trays (one of each species) and marked down, then they will be released back into the water. This will be carried out several times in different places, but around the same spot, on the water bodies to get as accurate results as possible. Also if a species is missed in one place it may be found in another but a little farther down stream.
Then by using a key (found on page A), which determines how polluted a water body is by what species it has in it, the pollution levels of the two water bodies being investigated can be determined.
Precautions and limitations
Ideally, each of these tests would be done every 4 hours or so to obtain max accurate results, because then the changes could be seen during the night aswell as the day, yet this isn't possible because of the time limit and limited facilities. So instead, the two water bodies are going to be investigated both on the same day, this is because if they weren't, it could be raining one day and not the other. This would affect the results considerably, e.g. if the rain that fell was acidic, it would cause the water bodies to be acidic also.
These tests to see how polluted the water was were chosen because it was thought that they were some of the most effective and would provide a good enough result for this investigation. Also, some of the chemicals used in the tests can be harmful if not used properly, so care must be taken when carrying out the tests.
Also, when investigating the stream, the kick test can be carried out in the middle or at the edges because it isn't very deep. Yet in the Trent, the middle part is extremely deep \ the kick test cannot directly be done there, only at the edges. This is a limitation because there might be organisms living in the middle of the river Trent that may never be seen in this investigation because they couldn't be reached. Yet in the stream almost all the possible organisms could be found because of the access all areas (apart from the parts where there are isolated pools; these could contain certain organisms that may not live in the actual water body being investigated).
Handling and analysing data
The Trent biotic index will be recorded in a table like the one below. This shows the type
This example would show that that Baetis mayfly was present in the Downs banks stream but the Rithrogena mayfly wasn't, and that neither of the two species was present in the river Trent.
Also to show the results of the other three tests a table will also be drawn as shown below. This shows the levels of nitrates, the pH and the dissolved oxygen content
This example would show that the pH is slightly alkaline which isn't the appropriate reading of natural water, which is slightly acidic, showing some slight pollution. Less than 5 parts/million in the nitrate test would show that there was hardly any pollution from nitrates which would be a good thing. The result of the oxygen test would be average showing that there wasn't any major change in the oxygen content.
I think that the river Trent will be more polluted that the Downs banks stream will be. This is because the Trent is down stream from an industrial town and there are quite a few sources of pollution there (see above in the introduction for the reasons). E.g. rubbish dumped by public, hot water from industries getting pumped into the rivers and reducing the amount of dissolved O2 and killing off aquatic organisms, etc.
Yet the Downs banks stream is in a national park, which means that it is protected, \ won't be as polluted because there are no industries putting hot water into it, or any farmland nearby where nitrates and other chemicals can get into it. Or any sewage works discharging pollutants into the water. It is considered to be very clean because the local water authority use it to compare other polluted water bodies to. So I think that this will be the most unpolluted out of the two.
I also think that the most effective way of investigating how polluted the water bodies are, will be the Trent biotic index. I think this because most aquatic life forms are quite sensitive to any severe pollutions, there are the few species that are tolerant to a certain amount of pollution, yet the majority prefer cleaner waters \ the Trent index will show which of these organisms are present in both water bodies.
By looking at the Trent biotic index results, I can see straight away that the Downs Banks stream had the larger diversity of species compared to the River Trent. This already shows that the River Trent is perhaps more polluted than the other stream, because of the amount of different species.
By looking closer at the results, living within the Downs Banks stream there are several species that are quite sensitive to even the slightest pollution, e.g. mayflys and stoneflys, \ this immediately shows that this stream must be very clean to support these pollution sensitive organisms.
Yet in the River Trent there are aquatic organisms e.g. leeches, which can with stand some pollution and I can see that there aren't species that can't withstand pollution. Also, I can see that some of the species that were present in the Downs Banks stream, were not present in the River Trent. This shows that the River Trent is significantly more polluted than Downs Banks stream.
Also by using the Trent biotic key (see page 6) the pollution level of each of the two water bodies could be determined. This was done by looking at what species were present in the streams and putting this info to the table on the back of page 6 and working the number out:
Downs Banks stream-9-10- Diverse fauna including several sensitive species; no organic pollution.
River Trent-5-6- Low diversity, no sensitive species present; intermediate pollution.
Then by looking at the other test results I can also see that these show that the River Trent is more polluted than the Downs Banks stream. I can see this because in the pH test, the River Trent is slightly more acidic than the stream, therefore, there must be a source before the point that was investigated along the Trent, that is making the water slightly more acidic. Although, by looking at the readings- 7.8 and 7.6, these two are both quite neutral which isn't the natural pH of rain water which is 5.6 (quite acidic). This is probably so because of other natural sources in both water bodies that makes this water slightly more alkaline than natural rain water.
The results of the nitrate test didn't really give a difference between the two because both of the results were less than 5. This means that both streams weren't polluted by any nitrates and so identifying which of the two had the most pollution by the results of this nitrate test would prove to be difficult.
By looking at the dissolved oxygen test results, There is a difference in both of the water bodies. This difference backs up what was predicted, that the River Trent has the lowest oxygen content out of the two. This could be so because of the industrial town up stream which would use the water as a coolant in the industries, then pump it straight back into the stream again, and it would be at a slightly higher temp than before. This means that the oxygen would be less likely to stay in the water and would evaporate out, leaving less for the aquatic life. Which would have trouble respiring on less oxygen and would most probably die. This would occur more in the River Trent because its O2 content was the least out of the two.
Overall, I think that the whole experiment went quite well, the results obtained were generally what we expected; that the River Trent is more polluted than the Downs Banks stream. I think this is so because the Downs Banks stream is located in a national park therefore is protected from any sources of pollutants that aren't naturally there already. This includes litter, human waste, fertiliser run-off, etc, this is because the stream isn't near any farmland or any urban areas for the public to pollute it. Also, this stream is used by the local water authority to test and compare against other water bodies in the area, because it is one of the cleanest around this area. This means that pollution sensitive organisms can live in these waters because they are relatively fresh and that's why we found some.
Yet the River Trent is going to be more polluted because it is just down stream from a major industrial town which means that the public have access to throw their rubbish and waste into it. Also it is down stream from a sewage works, this means that sewage will go into the sewage works, be treated and the resulting water from the treated sewage will then be released back into the River Trent. The water will \ contain more pollutants and chemicals which will be harmful and kill pollution sensitive aquatic life. That is why in the River Trent there were no organisms like mayflys.
If the investigation were to be carried out again with more time and better facilities I think that a few improvements could be made. More accurate equipment would be used, e.g. the nitrate, pH and dissolved oxygen tests would be more accurate to obtain better results. Also, the net could have even smaller holes to catch even smaller organisms that probably fell through the other net. The pictures in the Trent biotic index were not as good as I think they could have been, so if it were to be carried out again an index with more detailed pictures would be more useful, because there was abit of trouble in identifying some of the species.
Also, the tests that were carried out were suffice for this investigation, but to obtain even more accurate results I think that different tests could be carried out, e.g. phosphate test to see if there was too much fertilisers in the water. Or a dissolved carbon dioxide test could be carried out.
Moreover, there wasn't enough time to carry out these tests more than once \ this meant that the results obtained may not be as accurate as they could be. They could all be a fluke from that day, perhaps because one of the two may have had a major pollution flow from a nearby pollution provider. Also, the temperature would be recorded to see any rises or decreases, or differences between the two. A temperature increase in water results in a decrease in oxygen content \ would support less life than if it were lower in temp.
The kick tests were carried out ten times in the same area