The Process of Marine Photosynthesis and Factors Affecting It

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First overall, primary production is the process of organic material made through photosynthesis and known to be the first step that structures the base of marine food cycle. In this vast ocean almost all primary production is carried out by chlorophyll (single-celled organisms mention as phytoplankton). The study of Biological Oceanography includes viewing the factors that influence primary production by means of allows many scientists to predict the future changes of these marine organisms. Notwithstanding the gaps mentioned above, this essay explores the main influencers of primary production processes.

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Factors Influencing Limiting and Enhancing Primary Production

Light limitation, the surface of the ocean intends to have more light, when it comes to ocean depth quality and quantity of light determines the amount of photosynthetic actives (Photosynthesis is regulated by the Increases or decrease of light intensity). As example, diving or snorkeling within open water a person is able to observe the light penetration. It is possible for light to penetrate many meters in clearer waters since unless there is an interference caused by large spread of sediment or other relative maters which could prevent the light from penetrating. This action makes divers and snorkeler have foggy visibility including difficulty to see at a certain distance. It doesn’t matter if the water is clear under the depth of 1000 meters, light will not penetrate beyond this water level.

Nutrient Limitation

Trichodosemeium is a species that come from a group of bacteria call the “cyanobacteria”. This species has the ability to reduce nitrogen gas, and flourish in water where nitrogen is limited. In oceanic system phosphorus is a limiting nutrient. However, in phosphorus-limited systems there is evidence that at least cyanobacteria adapt their metabolism to produce higher proportions of Sulphur and sugar-based membrane lipids instead of phospholipids in order to decrease the cellular demand for phosphorus.

Iron Limitation

Marine ecological production processes are limited by iron because it does not only differentially impact on different phytoplankton taxa but also influences modification of other elements’ biogeochemistry during growth of phytoplankton. When iron is a limiting factor, it results into increased uptake of silicic acid relative to nitrogen and carbon. Therefore, when iron is a severely limiting factor in marine ecological production, it leads to increased ratios of Si: N from iron replete growth of one to 5 and/or more ratios. However, the concentrations of iron have no impact on the ratios of carbon: nitrogen.Therefore, silica significantly enhances growth of diatoms known to be produced under high iron limitation. Similarly, the same condition leads alteration in the depth of silica, nitrogen, and carbon. By way of illustration, iron limitation negatively impacts on direct stimulation in the growth of bacteria because it influences improved growth of phytoplankton-derived DOM. In HNLC waters, growth heterotrophic bacteria are rarely limited by limited iron. The inconsistency of HNLC condition is explained by low solubility in seawaters coupled with lowiron atmospheric flux. Extracellular release of siderophores or iron-binding ligands may also explain the persistent limited growth of heterotrophic bacteria because with low concentrations of iron in seawaters, the secretion of Siderophores is negatively impacted. Upon binding with iron binds with siderophore, the complexity of siderophore-iron is experienced by the cell and internalized via cell-surface receptors leading to a condition where the iron is catabolized after being reduced.

Temperature Limitation

The limitation of increasing seawater temperatures has three main effects of primary ecological production processes including macroalgal assemblages. It has the effect of increasing the rates of respiration by altering the ratio of respiration to photosynthesis and reduces long-term net effect of primary productivity. Increased photo inhibition may be observed in a condition of high irradiance and high temperature combined leading to a decrease in NPP when the environment is characterized by high irradiance. Finally, temperature limitation has an effect of canopy layering which may, in turn, contribute to increased rates of respiration in full assemblages. It is because canopy layering makes algae beneath experience lower light intensities leading to adverse impact of exacerbated temperature. Despite the fact that respiration rates of thalli are minimally affected by increased temperatures, there can be a larger negative effect of enhanced respiration rates and delivery of light underneath canopy layer on total assemblage NPP.

Factors Influencing and/or Enhancing Primary Production Processes

Primary ecological production processes involves fixation of carbon by photosynthesis. In the ocean, there is variance in light field depending on the time of the year, time of the day, and depth. On several scales, there occur temporal variations ranging from annual to seasonal, diurnal, and seconds. Primary production is also influenced by various light regimes’ effect on phytoplankton populations’ adaptation including modification in each cell’s concentration of chlorophyll, alteration in the ratio of photosynthetic unit to chlorophyll-a molecules as well as changes in auxiliary pigments’ concentrations known to play a role of either a photosynthetic or photo-protective part. The phytoplankton biomass is affected by variability in light acts. Usually, environmental scientists treat the phytoplankton pigment’s concentration, chlorophyll-a, as phytoplankton biomass’s index since all types of phytoplankton contain divinyl chlorophyll-a due to the fact that it plays an integral part in the photosynthetic process. The tendency mentioned above impact on primary production process because based on other factors, there are variances in the rate of photosynthesis depending on the increased concentration of chlorophyll-a. Another factor determining primary marine ecological production processes is availability of nutrients essential for photosynthesis including nitrogen. In a water column of stratified ocean, the upper illuminated layer has little nutrients with most of the nutrients being the deeper layers. These nutrients are brought to the upper or surface layer by mixing events leading to improved primary production. In high latitudes and temperate regions, winter’s deep mixing events and subsequent stratification experienced during the start of surface warming contributes to the spring bloom which results into the primary production’s seasonal cycle in primary production. As a result, the impact of sporadic mixing events is imposed in reaction to passing storms. It leads to short-lived enhancements in primary production linked to the sporadic events mentioned above. The primary influencers of primary production are biomass and light. Indirect accountability can be done on other contributing factors including micronutrients, nutrients, temperature, and iron among others via their effect on the parameters of the irradiance-photosynthesis response function.


This essay explored why contrary to primary production, nitrate, iron, and carbon concentration and temperature limitation among other factors can be directly measured regarding their effect on the marine photosynthesis process. It is a biological primary production process that may only proceed without being interfered with the removal of phytoplankton from their natural environment. Earlier literature on marine primary production shed light to the current understanding regarding biogeochemical cycling and marine ecology. The research indicated that the findings on the impact variables mentioned above on marine primary production may significantly contribute to academicians, and environmentalists’ understanding about ocean life.

24 May 2022

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