Mangrove biotic factors are living components like; producers, herbivorous, carnivorous and omnivorous consumers, as well as mangrove decomposers.
They differ from the abiotic factors in mangrove ecosystems, which are generally non-living or inorganic in nature.
This article discusses the mangrove biotic factors and their attributes, as follows;
1). Mangrove Producers (as one of the Mangrove Biotic Factors)
The ability of primary producers in the mangrove ecosystem to independently manufacture food and energy from inorganic resources, makes them invaluable as an ultimate food source. As a result, producers always occupy the basal level of food chains and energy pyramids in the mangrove biome, from where they supply the required energy and nutrients needed by heterotrophs for their survival and metabolism .
Examples of primary producers in mangrove ecosystems are; algae, mangrove trees, phytoplankton, and epiphytes.
Algae in the mangrove ecosystem range from microscopic to macroscopic types, and differ in minute physiological and metabolic details. Mangrove algae tend to grow in attachment to surfaces like branches, roots and soil, and are prominent photosynthetic producers, while contributing to carbon and oxygen cycles of their environment.
Mangrove trees are arguably the most dominant and common primary producers in mangrove ecosystems.
They include highly-adapted vascular species that are hydrophilic and capable of thriving under the seasonal-fluctuating influence of tidal currents in intertidal saline/brackish coastal zones.
Roots of mangrove trees are specialized to acquire oxygen while being inundated under waterlogged conditions for extended periods, using organelles called pneumatophores .
Phytoplankton constitutes a fairly large and diverse group in the mangrove ecosystem. Members of this group include some species of microalgae, and some microscopic plants that are free-floating and most abundant during seasons of high-tide, when the water column rises significantly.
Epiphytes include some species of ferns, hoyas and orchids, among other plants that grow on surfaces of other plants . These autotrophs are not always parasitic, and may derive their nutrients from detritus and water within their reach.
2). Mangrove Herbivorous Consumers
Herbivorous consumers in the mangrove ecosystem are organisms whose diet is dominantly composed of autotrophic materials like algae and plant biomass.
These organisms are also called primary consumers, because they occupy one trophic level above the producers, and depend on them (producers) for food.
Through their activities, mangrove herbivores help to modify and regulate the ecologic conditions and structure of their habitat, including the trend of nutrient cycling.
Examples of mangrove herbivores are; mangrove snails, caterpillars, small crustaceans, and some kinds of fish, like rabbitfish.
Saltwater-tolerant snails in mangroves consume both fresh and decaying plant matter, so that their feeding habits range from herbivorous to detrivorous.
Caterpillars and other herbivorous insects consume mangrove foliage, while small crustaceans like sesarmid crabs feed on detrital plant litter .
Herbivorous fish are not core inhabitants of mangrove ecosystems, but may become regionally abundant when tides are high. These fish, such as rabbitfish and parrotfish, may occasionally exhibit omnivorous behaviors.
3). Mangrove Carnivorous Consumers (as one of the Mangrove Biotic Factors)
Carnivorous consumers that live in the mangrove ecosystem, include all organisms which feed exclusively on other consumers, especially those that are at a disadvantage by reason of size or biological advancement.
Food for these organisms comprises of invertebrates like crustaceans, and vertebrates like small fish.
Mangrove carnivores include some species of monitor lizard (like Varanus indicus), snakes, birds, fish, and some crabs.
The mangrove monitor is a predatory reptile that is adapted to saline water conditions, and preys on fish, crabs, and small mammals among other heterotrophic food sources.
Snakes in the mangrove ecosystem include the mangrove snake, taxonomically referred to as Boiga dendrophila, whose prey include frogs, lizards, small mammals like bats and rodents, and some birds .
Kingfisher and heron are carnivorous birds that can be found in mangrove ecosystems, where they prey on crustaceans, fish, and insects among other heterotrophs.
Carnivorous fish and crabs in mangrove ecosystems include snappers, barracudas, and large mud crabs whose prey include mollusks, worms, insects, smaller fish and crustaceans.
4). Mangrove Omnivores
Omnivores in the mangrove ecosystem include all heterotrophic organisms whose evolutionary conditions have caused them to adapt to a diverse range of food sources that cover both plant and animal biomass.
As a result of their dietary tendencies, omnivores are important to the ecosystem and play major roles in energy transfer at multiple trophic levels.
The omnivores in mangrove forests and swamps include the mangrove tree crab, periwinkle, mudskipper, and egret.
For these organisms, the ability to consume both plant and animal matter is driven by constraints in the availability of preferred food sources, either on a consistent or seasonal basis.
This is obvious in the fact that mangrove omnivores in fact have preferential food sources which they would consume more than others, if available.
For example, the mangrove tree crab (Aratus pisonii) is more carnivorous in its preference of food sources, but can consume a variety of plant materials which are more accessible .
The vast biodiversity of mangrove omnivores is evident in members like the mudskipper, which is a fish with distinctive amphibious characteristics that include possession of both lungs and gills . These organisms are saltwater-tolerant and very adaptive, surviving on food sources like small crustaceans, detritus, algae and some insects.
Mangrove birds like the Snowy egret are suited for an omnivorous role because they are ecologically resilient and opportunistic. Their diet consists of similar options are other omnivores in their environment, including insects, crustaceans, and plant matter like seeds.
Many of the omnivores found in mangroves are fairly broad in their geographic reach; and may occur along the entire coast, in all kinds of saline/brackish wetlands, and even in some terrestrial ecosystems.
5). Mangrove Decomposers (as one of the Mangrove Biotic Factors)
Decomposers in the mangrove ecosystem are organisms whose feeding activities facilitate biodegradation or breakdown of plant and animal matter, to yield simpler elemental nutrients that can be absorbed and recycled.
Their food sources include; organic waste, and remains of dead animals and plants.
Examples of mangrove decomposers are; bacteria and fungi; as well as some detrivorous invertebrate organisms like shrimp, nematodes, and termites that can feed on decaying-wood debris and other detrital materials.
Mangrove biotic factors are;
1. Mangrove Producers
2. Mangrove Herbivorous Consumers
3. Mangrove Carnivorous Consumers
4. Mangrove Omnivores
5. Mangrove Decomposers
1). Dolorosa, R. G. (2014). "Notes on Mangrove Snake Boiga dendrophila multicincta (Boulenger, 1896) in Iwahig River, Puerto Princesa City." Available at: https://aquadocs.org/handle/1834/17910. (Accessed 28 May 2023).
2). Erickson, A. A.; Feller, I. C.; Paul, V. J.; Kwiatkowski, L. M.; Lee, W. (2008). "Selection of an omnivorous diet by the mangrove tree crab Aratus pisonii in laboratory experiments." Journal of Sea Research 59(1-2):59-69. Available at: https://doi.org/10.1016/j.seares.2007.06.007. (Accessed 28 May 2023).
3). Herbon, C. M.; Nordhaus, I. (2013). "Experimental determination of stable carbon and nitrogen isotope fractionation between mangrove leaves and crabs." Marine Ecology Progress Series 490:91-105. Available at: https://doi.org/10.3354/meps10421. (Accessed 28 May 2023).
4). Muro-Torres, V. M.; Amezcua, F.; Soto-Jiménez, M. F.; Balart, E. F.; Serviere-Zaragoza, E.; Green, L.; Rajnohova, J. (2020). "Primary Sources and Food Web Structure of a Tropical Wetland with High Density of Mangrove Forest." Water 12(3105). Available at: https://doi.org/10.3390/w12113105. (Accessed 28 May 2023).
5). Sahoo, G. (2018). "Mangrove Pneumatophores: Oases Of Biodiversity In Mangrove Mud." Available at: https://doi.org/10.31988/SciTrends.19487. (Accessed 28 May 2023).
6). Wilson, J. M.; Kok, T. W.; Randall, D. J.; Vogl, W. A.; Ip, K. Y. (1999). "Fine structure of the gill epithelium of the terrestrial mudskipper, Periophthalmodon schlosseri." Cell Tissue Res. 1999 Nov;298(2):345-56. Available at: https://doi.org/10.1007/s004419900101. (Accessed 28 May 2023).
7). Yong, J. W. H.; Wang, J. W.; Khew, Y. T. J.; Sheue, C.-R.; Wong, W. S. (2014). "A Guide to the Common Epiphytes and Mistletoes of Singapore." Centre of Urban Greenery and Ecology, National Parks Board, Singapore. Available at: https://www.researchgate.net/publication/263851259_A_Guide_to_the_Common_Epiphytes_and_Mistletoes_of_Singapore. (Accessed 28 May 2023).