Light And Photosynthesis In Aquatic Ecosystems PDF …

Light And Photosynthesis In Aquatic Ecosystems

LIGHT AND PHOTOSYNTHESIS IN AQUATIC ECOSYSTEMS

Implications of these tests:

This controlled test has aquatic implications, as photosynthesis is the same whether it be a terrestrial plant, a freshwater aquatic plant, or symbiotic zooanthellic algae found in corals.
The main difference would be that light energy is quickly absorbed by water, especially red light waves and many modern high-end LED fixtures such as an EcoTech Radion, AI Sol Vega Blue, ZetLight ZT 6600, AAP Fiji Blue, AAP Ocean Blue NP, and AAP Reef White 2000 produce the light energy for deeper aquarium water penetration more comparable to the popular 20k "Radium" Metal Halides.

Light And Photosynthesis In Aquatic Ecosystems - …

Far worse yet would be the cheaper no name emitters used by manufacturers such as BaiSheng, Epistar, & others sold under a plethora of other names for so-called aquarium use. These use daylight emitters that can vary widely in Kelvin Color output from only 2000K to 6500K and are in reality generally much less efficient for photosynthetic aquarium life use other than just plain light!

Think about why a CFL 10,000K daylight is so much different and more expensive than a common household CFL sold in hardware stores, or the many decorative LED aquarium lights or even those for home or flashlight use. Try using one of these to grow your delicate coral or plants (the answer is they will not without use of many). This is the reason most LED aquarium lights were not adequate for supporting life properly until about 2008-9.

The downside is the heat that MH lights produce, often resulting in the need for hood fans and even chillers, although the newer open design units such as the EcoSystems USHIO double end fixture and HQI bulb works well for 10-25 or even larger aquariums when other lights are included in the "mix" without a chiller.


Light and photosynthesis in aquatic ecosystems

Aquatic bryophytes occupy streams, lakes, and wetlands where they face limited CO2 in solution, limited CO2 diffusion, high boundary layer resistance, and loss of light with depth, especially red light. Limitations to photosynthesis in the water are therefore somewhat different from those on land. Of primary importance is the availability of CO2 and hence, pH is important in determining the availability of this gas. There is also limited evidence that some mosses might be able to convert bicarbonates to CO2 at the moss surface or within the cell to increase access to carbon. The often one-cell-thick leaves permit light and CO2 to reach photosynthetic cells directly, but boundary-layer resistance can reduce CO2 uptake. Other nutrients can be somewhat limiting, especially phosphorus and nitrogen. Sedimentation, and overgrowth by diatoms, other algae, and detrital complex, can block light, and water decreases the light with depth. This is further complicated by the rapid attenuation of red light. The aquatic environment protects chlorophyll from UV radiation, and in areas with high light intensity, at least some bryophytes produce enhanced pigmentation to serve as a filter. In dry seasons, lack of water can limit or halt photosynthesis. Temperature also can be a problem at this time, with exposed but still hydrated mosses in some cases reaching temperatures unknown in submersed conditions, and causing elevated respiration that can exceed photosynthetic fixation. High temperatures may greatly limit the presence of many cosmopolitan species of aquatic bryophytes in tropical regions. Contrarily, many aquatic mosses have temperature optima in the 0–20 °C range, with optima depending on their usual habitats.

Light and photosynthesis in aquatic ecosystems - …

Light-acclimation processes are central to allowing photosynthesis in aquatic ecosystems to span from high light conditions, that are 10-fold higher than the light levels required to saturate photosynthesis, to the deep sea with extremely low light levels. In dim light systems, nutrient levels are often high, and cells maximize the absorption of light by increasing the cellular pool of pigments. The upper limits of light absorption are constrained by the package effect, which ultimately restricts the benefit of the light absorption associated with an increase in cellular pigmentation, thus decreasing the cost/benefit ratio relative to the metabolic cost of manufacturing cellular light-harvesting pigments. At extremely low light levels in the deep sea, chloroplasts are sequestered in numerous organisms; however, these species are not obligate autotrophs and supplement a heterotrophic/mixotrophic existence with opportunistic autotrophy. While low light acclimation is based on maximizing light absorption, photosynthetic systems under high light, in addition to decreased light-harvesting cross sections, rely on energy-dissipation processes to avoid light-induced damage to the photosynthetic apparatus and other free radical susceptible cell structures. Dissipation of excess light energy represents the largest sink of the absorbed light in high light environments; however, these processes remain largely unstudied and are rarely quantified. Cells supplement their energy-dissipation processes through increasing the capacity to remove high-light-generated radicals and/or inducing vertical movement. Improved understanding of strategies remains central for the understanding of algal distributions in nature and has broad industrial implications.