Phytoplankton an Introduction

T.A. Baig

Phytoplankton•Phytoplankton are the autotrophic components of the plankton community and a key factor of oceans (Euphotic zone), seas and freshwater basins ecosystems. Green color is due to chlorophyll and some other accessory pigments like  phycobiliproteins, xanthophylls is also present.

•As the main primary producer, phytoplankton is an important link between the physical and chemical elements and higher tropic levels in the marine food web

• Changes in the environment could affect the annual succession and species composition of the phytoplankton, as well as the overall primary production in the area.

• Phytoplankton monitoring will give important information regarding biological changes on the lowest level in the food web with environmental impact and climatic changes.

Dinoflagellates are generally smaller than diatoms (can be as small as 10 micrometers). They usually occur as single cells.

Typical dinoflagellate forms have a body surface with two grooves, each having a "whip-like" flagellum they use to swim.

Some dinoflagellates are plant-like (get energy from the Sun), others are animal-like (consume other organisms for energy), and some are both.

There are bioluminescent dinoflagellates and toxic species, too.

Diatoms have rigid cell walls consisting of two closely fitting halves; they are like miniature greenhouses, protecting internal plant matter within glass walls.

These algae occur as single cells, chains and colonies. Cell sizes range from 5 to 1000 micrometers. 

Centric diatoms have circular, triangular, or pillbox shapes. 

Pennate diatoms are elongate with bilateral symmetry. Diatoms may have spines or other projections and some are toxic.

Diatoms 

The Black Sea haven’t so black after all. This image, captured by NASA's Aqua satellite, shows it in vibrant shades of cyan, turquoise and blue. The swirling patterns on the surface of the water are caused by blooms of microscopic plankton known as coccolithophores.

PSP - Paralytic shellfish poisoning

Paralytic shellfish poisoning (PSP) is one of the four recognized syndromes of shellfish poisoning, which share some common features and are primarily associated with bivalve mollusks (such as mussels, clams, oysters and scallops). These shellfish are filter feeders and, therefore, accumulate neurotoxins, called Saxitoxin, produced by microscopic algae, such as dinoflagellates, diatoms, and cyanobacteria. Dinoflagellates of the genus Alexandrium (genus) are the most numerous and widespread saxitoxin producers and are responsible for PSP blooms in subarctic, temperate, and tropical locations. The majority of toxic blooms have been caused by the morphospecies Alexandrium catenella, Alexandrium tamarense, andAlexandrium fundyense, which together comprise the A. tamarense species complex. In Asia, PSP is mostly associated with the occurrence of the species Pyrodinium bahamense. Human toxicity and mortality can occur after ingestion of these animals, but toxicity is also seen in wild animal populations.

Symptoms: Symptoms can appear ten to 30 minutes after ingestion, and

include nausea, vomiting, diarrhea, abdominal pain, tingling or burning lips, gums, tongue, face, neck, arms, legs, and toes. Shortness of breath, dry mouth, a choking feeling, confused or slurred speech, and loss of coordinationare also possible.

Coccolithophores  is a unicellular, eukaryotic phytoplankton (alga) Coccolithophores surround themselves with plates made of calcite

(CaCO3). Known as coccoliths, these plates have a variety of shapes, which are also important microfossils

Single coccolithophores are commonly smaller than 20 micrometers across and are often enclosed by over 30 plates.

Coccolithophores can form enormous blooms, turning seas an opaque turquoise color.

The most abundant species of coccolithophore, Emiliana huxleyi,  It is found in temperate, subtropical, and tropical oceans

 It is studied for the extensive blooms it forms in nutrient depleted waters after the reformation of the summer thermocline. and for its production of a group resistant alkenones (lipid, 35-41C)commonly used by earth scientists as a means to estimate past sea surface temperatures. Coccolithophores are of particular interest to those studying global climate change because as ocean acidity increases, their coccoliths may become even more important as a carbon sink

coccolithophores These little single-celled organisms suck carbon from the

atmosphere, combining it with calcium and oxygen to form little plates of calcium carbonate known as coccoliths. Something akin to limestone body suits, they resemble floating hub caps. When they die, they slowly sink to the ocean floor, eventually being consumed and excreted by other sea life.

In this way, coccolithophores play a vital role in the ocean's "biological pump". This is a part of the carbon cycle that transfers carbon from the air into the ocean depths. Microscopic sea organisms such as coccolithophores speed this up, lowering the concentrations of carbon dioxide in the atmosphere as they calcify and sink into the sediment.

Phytoflagellates

Phytoflagellates are diverse, crossing ten classes of algae. These motile organisms are so small they must be identified using powerful microscopes or biochemical techniques. Phytoflagellates are very abundant and often dominate the phytoplankton when larger forms -- i.e., diatoms and dinoflagellates -- are low in concentration.

Pediastrum, a flat colony of green algae

Photosynthetic bacteria are some of the smallest -- and largest-- phytoplankton.

They exist as small single cells (less than 1 micrometer in diameter) but some forms clump together to form "bundles" that can be seen by eye.

Photosynthetic bacteria are major contributors to oceanic primary productivity. One type, Prochlorococcus, may be the most abundant species on earth.