What is the difference between algae and alga

As oxygen is required for fish and other aquatic organisms, a decrease in photosynthesis productivity is detrimental to aquatic populations. Without phytoplankton, the oxygen supply of the ocean would be cut in half.

In both fresh and saltwater, a lengthy decrease in phytoplanktonic productivity can lead to a fish kill massive fish die-off 1. Although phytoplankton require sunlight for photosynthesis and oxygen production, too much light can be harmful to photosynthetic production. On very bright days, UV-B radiation can diminish photosynthesis by 8. This is why photosynthesis rates peak during the morning, and decrease at noon when the radiation levels are highest 1. While phytoplankton rely on photosynthesis to produce sugar for energy, they still need other nutrients to grow and reproduce 7.

These nutrients are typically phosphorus, nitrogen and iron, though some species also require silicon, calcium and other trace metals 11, The more nutrients particularly phosphorus that are present in a body of water, the more algae and phytoplankton that will grow 7. An increase in the nutrient concentration of a body of water is called eutrophication Eutrophication is often an indicator of agricultural runoff, which can raise phosphorus and nitrogen concentrations to very high levels.

If there are too many nutrients, the algae will form a bloom, which can be very detrimental to water quality and aquatic health 7. The lack of iron in the open ocean limits phytoplankton growth Nitrogen and phosphorus are also scarce away from coastlines, and can be limiting factors as well However, ocean circulation can cause an upwelling, which moves deep, nutrient-rich water up into the photic sunlight zone , replacing the nutrient-depleted surface water Upwelling, seasonal ice melts and agricultural runoff can all increase nutrient levels, leading to an increase in phytoplankton populations.

In temperate fresh waters, growth is limited in winter because light and temperatures are low. A large increase in the spring normally occurs as light conditions improve and water begins to mix 1. In the summer, phytoplankton flourish until the nutrient supply begins to run low.

In tropical lakes, the phytoplankton distribution is fairly constant throughout the year and seasonal population changes are often very small 1. In temperate and subpolar waters, the seasonal fluctuations are normally fairly large.

Fluctuations in population also occur if agricultural runoff brings additional nutrients into a body of water. Saltwater phytoplankton can be found all over the world, living in the photic sunlit zone of the ocean.

Cyanobacteria prefer to live near the bottom of this zone, closest to the nutrient-rich deep water while still receiving enough sunlight for photosynthesis 1.

However, in any marine environment, phytoplankton populations vary not only by season but by region. Algae blooms can occur near the poles in the spring, when there is plenty of sunlight and the melting sea ice leaves behind nutrient-rich freshwater This melting process also fuels the oceanic convection, or circulation In coastal and open-ocean environments, oceanic circulation is responsible for phytoplankton concentrations.

This circulation can cause upwelling bringing nutrient-rich water to the surface and instigates phytoplankton transportation. Like sea ice melting, upwelling is a seasonal occurrence. The extent and location of upwells are based on wind patterns, which cause currents across the globe Surface water is carried away from coastlines by currents, and is replaced by cold, nutrient-rich water from below In many coastal regions, southerly winds cause this coastal upwelling in late summer and autumn As upwelling brings nutrient-rich water up to the surface, phytoplankton blooms often appear at this time.

Oceanic circulation and upwelling ensures that the coastal environments have the highest rates of primary production in the ocean Tides, flooding and currents all encourage higher nutrient levels in the photic zone Phytoplankton are an important aspect of a healthy body of water.

Algae and cyanobacteria help to provide oxygen and food for aquatic organisms As a key component, an imbalance of phytoplankton levels can cause major problems. If too many nutrients are available, it can trigger an algal bloom Algal blooms and overproduction of phytoplankton can cause toxic red tides and fish kills. On the other hand, phytoplanktonic productivity can be limited by a lack of required reactants such as sunlight. This decrease in productivity can also lead to fish kills 3.

An algal bloom is a sudden increase in the concentration of phytoplankton. During a bloom, clear water can become covered with phytoplankton within days These algal blooms can grow large enough to be seen from a satellite, covering hundreds of square kilometers Algal blooms come in many colors from green to red, brown, blue, white or purple Under the right conditions, algal blooms can last one week to an entire summer, despite the short, few-day life span of phytoplankton A single bloom will only last one to two weeks, as the phytoplankton population will die without the proper oxygen and nutrient levels.

However, if the water conditions stay favorable, successive blooms can occur and appear to be one continuous population Algal blooms are most common in late summer and early fall. There are several causes that can contribute to an algal bloom. These blooms can occur seasonally, after an upwelling of nutrient-rich water, or due to pollution such as agricultural runoff.

In both cases, the water becomes saturated with nutrients, creating an ideal environment for phytoplankton productivity Even natural causes can trigger an algal bloom, such as a rainstorm followed by warm, sunny weather 1. Rain can contribute runoff, or encourage the mixing of nutrient-depleted and nutrient-rich layers of water.

When nutrient levels rise, phytoplankton growth is no longer nutrient-limited and a bloom may occur If a phytoplankton concentration stays steady after the initial bloom, it may become a red tide. While some blooms are harmless, others may produce toxins that endanger aquatic life and humans. This harmful algal bloom is known as a red tide. While red tides specifically refer to harmful algal blooms HABs , they are often simply associated with the discoloration due to a large concentration of phytoplankton 53, Although known as a red tide, the discoloration from a harmful algal bloom is not always red.

The color of the tide depends on the pigments present in the phytoplankton In some cases, the bloom cannot be seen by the human eye, though it is still releasing toxins Red tides and the toxins they release can have a direct or indirect impact on the health of humans and other organisms.

These harmful algal blooms can also cause shellfish poisoning in humans and other adverse effects Even during non-toxic algal blooms, the aquatic environment can be compromised. Massive levels of phytoplankton respiration and decomposition can reduce dissolved oxygen to unsustainable levels, resulting in the deaths of other aquatic creatures The phytoplankton that cause a red tide are usually comprised of dinoflagellates, diatoms or cyanobacteria.

Certain species of these phytoplankton can contain harmful toxins that can affect humans and other animals. At normal levels, heterotrophic bacteria in the water break down the toxins in these organisms before they can become dangerous When an algal bloom appears, the concentration of toxins increases faster than the bacteria can break it down.

Some of these toxins cause mild problems if consumed by humans, such as headaches and upset stomachs, while others can cause serious neurological and hepatic symptoms that can lead to death These effects can be caused by direct or indirect contact with an algal bloom. Direct exposure can occur from swimming or drinking affected water. Indirect contact can occur from eating animals that have been exposed to the toxic bloom, particularly shellfish.

Shellfish are susceptible to toxins because they are filter feeders. Filter feeders ingest food by taking up the water surrounding them and then filtering out what they do not wish to ingest This method accumulates toxins inside the shellfish system.

Organisms that eat the shellfish including humans are consuming the concentrated toxins, which can reach deadly levels Filamentous algae is a collection of microscopic algae that clumps together in strings and mats at the surface of the water 7. These accumulations can vary from a small, woolly patch near shore to a widespread, slimy green covering.

Filamentous algae are often referred to as pond scum, and appear in eutrophic nutrient-rich bodies of water. More often than not, filamentous algae are more of a nuisance than a danger 7. They are somewhat more controllable in that the algae clumps can be physically removed from the water 7, While large filamentous algal blooms will stop sunlight from penetrating the water and reaching submerged plants, the biggest threat associated with them is oxygen depletion If an algal bloom appears, a fish kill can occur shortly thereafter due to the environmental stresses caused by the bloom.

A fish kill, also known as a fish die-off is when a large concentration of fish die. The most common cause of this event is lack of oxygen If a phytoplankton population grows to an excessive amount, the amount of usable oxygen in the water can be depleted Oxygen depletion has two algal-bloom-related causes: respiration and decomposition.

Algae and cyanobacteria consume oxygen at night respiration when there is not light for photosynthesis If there is a bloom, the phytoplankton and other aquatic organisms like fish can consume more oxygen than is produced. Likewise, if large portions of the algal bloom die off at once, bacteria will start to consume oxygen in order to decompose the dead algae.

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I'm writing a Japanese - English translation and naturally used the plural form with a singular verb conjugation! Students: Are you brave enough to let our tutors analyse your pronunciation? Its use as an uncountable noun conjugated with singular verbs is also supported by the National Geographic style manual: "Occasionally algae may be considered a collective noun and treated as singular: A map shows how algae periodically blooms in the bay.