bornforthesea's Blog

Juni 7, 2010

Plankton Net ( Go in English )

Filed under: Uncategorized — bornforthesea @ 9:05 am

Definition plankton

Sea organisms are divided into three groups, namely benthos, nekton, and plankton. Bentos are organisms that inhabit the bottom waters. Nekton are larger organisms with swimming activities in the pelagic area. Plankton are defined as organisms drift (no swimming ability), anything that lives in the pelagic zone (upper part) ocean ,sea , and bodies of freshwater .

Plankton is one of the most important organisms on earth, since it’s become food for aquatic life. For most marine of organisms, plankton is the main food. Plankton living on the coast where he received supplies of salt minerals and adequate sunlight. It is important to allow them to survive. It’s not surprising that there are lots of fish in coastal areas. That’s why active fishing activities carried on in this area.

Plankton are organisms that drift or float in life pelagic regions. However, there are also plankton with strong swimming ability so that it can perform daily migration.

Plankton divided into two major groups of phytoplankton (plankton plant or vegetable) and zooplankton (animal plankton).

a. Phytoplankton

Phytoplankton are autotrof component of plankton . Autotrof is an organism that is able to provide / synthesize their own food in the form of organic material from inorganic material with energy supply like the sun and chemicals. Autotrof component serves as a producer.

The name a phytoplankton is taken Greecephyton or ” plant “and πλαγκτος (” planktos “), meaning” wanderer “or” flower “. Most of the phytoplankton size is too small to be seen with the eyes . However, when in large numbers, they can appear as a green color in the water because they contain chlorophyll in their cells (although the actual color may vary for each species of phytoplankton as chlorophyll which is different or have extra pigment like phycobiliprotein).

There was a large phytoplankton and small, the large one are usually caught by plankton network that consists of two major groups, namely diatoms and dinoflagellate. Diatoms are easily distinguished from the dinoflagellate because of its shape like a box of unique glasses and don’t have motion stuff. In the process of reproduction of each diatom will divide itself into two. One half of the diatom life will occupy the top valve (epiteka) and second halves will occupy the lower valve ( hipoteka). While the second main group is characterized by a pair of dinoflagellate flagella which are used to move the water. Some dinoflagellate like Nocticula capable of producing light through a process bioluminesens (Nybakken, 1992).

Members of phytoplankton which is a minority is a variety of blue green algae (Cyanophyceae), kokolitofor (Coccolithophoridae, Haptophyceae), and silicoflagellata (Dictyochaceae, Chrysophyceae). Marine Cyanophyceae found only in tropical sea and visually make a form likes “carpet” filament and can be colorious the water (Nybakken, 1992).

Phytoplankton can only be found on the surface layer because of the requirements of his life in the places that have enough sunlight for photosynthesis. They will be more prevalent in places located in the continental shelf and along the coast where there is upwelling process. This area is usually rich enough organic materials.

Vegetable plankton called phytoplankton, are plants whose life float or drift in the sea. The size is so small as unvisible by eye. Generally, phytoplankton size 200-200 μm (1 μm = 0.001 millimeters).

b. Zooplankton

Zooplankton, also called animal plankton, is animals whose lives are floating, or floating in the sea. Swimming ability is very limited until its existence is very much determined where currents carry it. Zooplankton is heterotrophic, which means cannot produce their own organic material from inorganic material. Therefore, for survival, he was very dependent on organic matter from phytoplankton to the food. So, zooplanktonis more as a consumer of organic material.

The most common groups of zooplankton copepod, eufausid, misid (mysid), amfipod (Amphipod). Zooplankton can be found starting from the coastal waters, estuarine waters, in front of the estuary up to the waters in the middle of the ocean, from tropical seas to the polar waters.

Zooplankton are living on the surface and some are living in deep water. There also can perform daily vertical migration in the surface layer. Almost of all animals that can swim freely (nekton) or who live on the seabed (benthos) life beginning as zooplankton when still a egg and larvae. Few day ahead, towards the adult, the nature of the original life as plankton nekton or benthos turned into.

Plankton size is very diverse, from very small to big. Under this classification proposed by Sieburth et al. (1978), which is now widely used.

  • Makroplankton (20-20 millimeters)

Examples are Pteropods; Chaetognaths; Euphausiacea (krill); Medusae, ctenophores, salps, doliolids and pyrosomes (pelagic tunicates); cephalopod.

  • Mesoplankton (0.2 to 2 millimeters)

Most zooplankton are in this group, like metazoans; copepods; Medusae; Cladocera, Ostracoda; Chaetognaths; Pteropods; tunicates; Heteropoda.

  • Mikroplankton (20-200 m)

Examples are: large eukaryotic protist; most phytoplankton; Protozoa (Foraminifera); ciliates; Rotifera; young metazoans – crustacean (copepod nauplii)

  • Nanoplankton (2-20 m)

Plankton which escaped from the nets, but larger than 2 μm. Or size 2-20 μm; example: small eukaryotic protists; small Diatoms; small Flagellates; Pyrrophyta; Chrysophyceae; Chlorophyta; Xanthophyta

  • Picoplankton (0.2 to 2 m)

For example: small eukaryotic protists; bacteria; Chrysophyceae

  • Femtoplankton (<0.2 m)

Examples: sea Virus

Phytoplankton & Zooplankton abundance values can be based on abundance data, that can be processed to determine the community structure of phytoplankton and zooplankton.

K = Value of plankton abundance (ind / liter; cells / liter)
K = N x 1 x 1 n = number of species of plankton enumeration results (eng; cell)
f v f = fraction of employed
v = volume of water filtered (liters)

Plankton sampling method:

  1. Qualitative, that is intended to determine the types of plankton
  2. Quantitative, ie to determine the abundance of plankton related to the distribution of time and place.

Plankton net

Many tools were created for the purpose of water with, a tool often use for sampling with plankton as object is plankton net. Plankton net is the nets with mesh size adjusted to plankton. The use of nets is so simple, practise and also gained quite a lot of plankton. Ordinary net plankton net made of nylon, usually conical in shape with various sizes, but the average length of nets is 4-5 times the diameter of the mouth. Nets are used to filter the water and are therein plankton. Therefore plankton captured depends on the size of mesh size, the size of the mesh size used should be tailored to the type or size of the plankton which will be observed. For plankton relatively large size (especially zooplankton) using nets No.0, or No. 3, while more for the smaller plankton using No.15, or No.20. for shallow waters in tropical region, Wickstead advocated by the size of mesh size 30-50 μm for phytoplankton and small zooplankton. While for mezooplakton larger mesh size used in the size of 150-175 μm.

The final part there are bucket tool tip net collected plankton bucket. These tools are usually tubular container that easily removed from the jar. Bucket principle must meet the following requirements:

–  can easily be operated at sea

–  does not hold too much water.

In the study of quantitative analysis (galore), the volume of data required / discharge the filtered water through the nets, so that the abundance of plankton can be calculated with the tail unit per m 3 of water filtered. For the recording of water discharge, used flow meter using the formula:

V = volume of water filtered (m3)
V = R ap R = number of propeller blades rotating flow meter
a = area of net mouth (m2)
p = length of water column (m) which adopted a single round

Construction of a plankton net

  1. Ring: located above and serves as a binding rope and a towing a plankton net. The ring is usually made from iron. The diameter of the ring are varies depend on brand and type of plankton net, but in general the diameter of this ring is 15 – 25cm.
  2. Rope: used to connect nets with rings. The length of the string varies depending on the type of plankton net and plankton will be taken, but the rope is usually used size 25 – 50cm
  3. Wire: used to form the mouth of the net and nets can be adjusted as per our requested. Wire diameter is usually 31cm to 45cm for phytoplankton and zooplankton.
  4. Nets: used usually of nylon material. Mesh size of nets are usually 30-50 μm to 150-175 μm for phytoplankton and zooplankton, the net length of about 4-5 times the diameter of the mouth of the net.
  5. Bottle / bucket: function to save water samples have been filtered by a plankton net.
Various measures of the net eye (Muller gauze) based on trade numbers (Motoda 1957)
Number Amount Average Size Number
Trade Nets eye Average Length Trade Destination Collection
Gauze Muler Per inch Nets eye Japan
0000 18 1,364 mm GG 18
000 23 1,024 mm GG24
0 38 0,569 mm GG 40 Hydromedusa, Euphausiids, dll
3 58 0,333 mm GG 54 Copepoda, dll.
5 66 0,282 mm GG70 Copepoda, diatom, dll.
15 150 0,094 mm XX13 Diatom, dinoflagelata, dll
20 173 0,076 mm Mikrozooplakton
25 200 0,064 mm Mikrozooplakton
sumber: LIPI, 1997

Types of Plankton Net

Plankton Collection Method

The sampling method using a plankton net is divided into two different ways depending on the purpose we need, usually distinguished by:

  1. By Horizontal sampling: Sampling method is plankton in horizontal distribution of plankton intended to determine the horizontal. Plankton net at a point at sea, the ship is pulled toward the other point, take the sample slowly as the movement of vessels (± 2 knots), a plankton net is pulled to the distance and time (typically ± 5-8 minutes). How many filtered water was obtained from figures on the flow meter or by multiplying the distance between two points with diameter plankton net. Flow meter for increased accuracy. By the way horizontal limited sample in one layer only.
  2. The Vertical sampling: It is the easiest way to take samples from the entire water column (composite sample). When the boat stopped, plankton net down to the bottom with a weight attached it. After that plankton net pulled upwards with constant velocity. For fine mesh size used speed 0.5 m / sec for coarse mesh eyes 1.0 m / sec.
  3. Sampling in Italic (Oblique): nets down slowly when the vessel moved slowly (± 2 knots). Large wire angle with the vertical lines ± 45 ˚, after reaching the required depth than slowly pulled plankton net with the same angular position. The plankton samples obtained from different layers of trapped water. The weakness of this method is take too much time.

Preserved samples

After plankton removed from the bucket immediately preserved in a wide mouth bottle. Preservatives that are not specifically research usually use formalin 4% (was neutralized borax). The fluid is a mixture of technical formalin (formaldehyde-yield market sold 40%) was mixed with 9 part of water -containing samples. Whereas for specific research, the sample is cooled between -10 to -25 ˚ C to metabolism plankton does not work. To avoid the mistake of samples needed in the glue bottle label mentioned as below:

–  Station number

–  Date and time

–  Depth

–  Name of vessel

–  Any other necessary data

Plankton Sample Analysis

Four categories of plankton analysis is most easily done is volume, fresh weight, dry weight, and counting.

  1. Measurement volume (biomass): by determining the volume with the aim to know the number plankton quantitatively without identifying its composition (the volume of plankton per unit volume of water).
  2. Measurement of wet weight and dry weight: by eliminating the water contained between plankton by absorbing water with filter paper or a suction pump. Weighing is usually used to determine the weight zooplankton (not phytoplankton). Calculations used wet weight scales with high sensitivity. Dry weight obtained after the sample baked at a temperature of 50 ˚ C for 24 hours.  To reduce the water content until and get stable weight. Too high temperature causes the plankton lipid to be  organic compounds break down, or missing.
BS = Weight plankton wet / dry (mg/m3)
BS = 1 – P 2 1 = Weight of filter with paper samples (mg/m3)
S 2 = Weight of filter with no sample (mg/m3)
S = Volume of water filtered (m3)

Counting the number of abundance: common way to chop samples with sample dilution and then fraction / part of the sample is calculated. In a simple sum of shredded multiplied by the number of fractions.

Data Analysis and Making Conclusion

Data analysis: After the enumeration and tabulated the results obtained, researchers conducted the analysis with statistical methods. By determining the condition of the plankton community sector in waters used in the formula:

  1. Index of diversity: diversity of taxa to identify aquatic biota. The higher the index value, meaning the waters plankton community more diverse and not dominate. Indexs diversity based on Shannon & Weaver formula:
H = Σ Pi ln Pi ; Pi = ni
1 = 1 N
H = diversity index
ni = number of cells / fish of biota taxa i
N = number of cells / fish of biota taxa in the sample
S = number of taxa in samples of biota

1. Evenness Index: showing  distribution pattern of plankton, a relatively high index value indicates that the content of each taxon is not much different. The formula used is Pielou’s:

J = H J =Evenness index
ln  S H = diversity index
S = number taxa of biota in the sample

2. Wealth index: find out more or less equivocal and concentration of biota in one community:

d = S – 1 d = index taxa richness
ln N S = number of taxa in one sample
N = number of cell / tail of the taxa of biota in a single sample

If a community consists of a single taxon, the index value is zero.

Making conclusions: some important things to consider in taking the conclusions are:

  1. Sea plankton are not spread evenly, both horizontally and vertically.
  2. Many plankton perform vertical migration, that cause density difference between morning and evening.
  3. Stimulation of plankton near the coast varies especially around the estuary:
  4. Indonesia climate that is tropical with different environmental parameters (temperature, salinity, DO, nutrients) not too plain, it avite difficult for making conclusion.
  5. Conclusion plankton distribution and environmental factors that were observed simultaneously alco need respect to weather conditions, geographic, and biology at the time of sampling.


Ranges of abundance and Koposisi Plakton predominant in the eastern waters of Indonesia. 1997. Oseanilogi development center jakarta science institutions.

Nybakken, JW 1992. Marine Biology An Ecological Approach. Jakarta Gramedia

Source image:

Ranges of abundance and Koposisi Plakton predominant in the eastern waters of Indonesia. 1997. Oseanilogi development center jakarta science institutions. html


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