The tropical climate zone encompasses around forty percent of the earth’s surface and may be found between the tropics of cancer (placed at a latitude of 23.5 north) and Capricorn (located at a latitude of 23.5 south).
In this article, you will learn the Different Types of Tropical Marine environments that which fish live and are mainly originated.
The generally consistent high temperatures and high levels of humidity in the air are the primary ecological processes that are at work within this zone.
Even though the climate varies from region to region within the tropics, ninety percent of tropical ecosystems are hot and humid, regardless of whether the conditions are permanent or seasonal.
The remaining ten percent of tropical ecosystems are hot and dry, and the majority of these resemble desert ecosystems.
These differences can be attributed to factors such as height, elevation, wind patterns, ocean currents, the ratio of land to water masses, geomorphology, and vegetation patterns; more recently, these differences have also been attributed to large-scale environmental changes caused by humans.
Different Types of Tropical Marine Environments
A. Neritic Zone
Neritic zone is a marine habitat that is shallow and extends from mean low water down to depths of up to 200 meters (660 feet). This environment often corresponds to the continental shelf.
Both planktonic and animals that live on the ocean floor are able to engage in photosynthesis in neritic waters because of the variable levels of sunlight that reach these waters.
Because of its proximity to land, the zone is distinguished by the presence of a relatively high concentration of both biological and chemical activity.
Except in certain low-latitude zones that encourage the development of calcium carbonate deposits by creatures like algae, bacteria, and corals, the sediments on the bottom are often composed of coarse debris that originated on land.
The spray zone is found in the supralittoral zone, which is characterized by its great variability and extreme difficulty in habitation. Animals that live there must have considerable specific adaptations. The few species of fish that call this ecosystem home include, among others, gobies, eels, and clingfishes in predominant numbers.
The intertidal environment, which is also known as the littoral zone, is characterized by extreme conditions that occur during short periods of time.
These conditions are made worse by intermittent drying periods, which require the fish that inhabit this environment to have an extreme ability to overcome temperature, ionic, and respiratory disturbances.
In reality, the intertidal zone is a harsh habitat since the creatures that live there are constantly being tossed around by the waves and are confined to pools and mudflats.
The mudskippers and the blennies are two of the most well-known types of intertidal fishes. These fishes are true amphibians since they leave the water to feed on the mud or rock that is either in or above the splash zone.
Many species of fish that live in the sublittoral zone may be found in the intertidal zone as well.
These fish include species of stingrays (Dasyatidae), flounders (Bothidae and Pleuronectidae), soles (Soleidae), bonefish (Albula), eels (Anguilla), moray eels (Muraenidae), clingfish (Gobiesocidae) (Ophidiidae). On the subject of the ecophysiology of intertidal fishes and their biology, there have been a lot of reviews written.
In the inner littoral zone, when seasonal changes are near maximum and light conditions enable high productivity, a wide collection of fishes can still thrive.
Surfperch (Embiotocidae), skates (Rajidae), sharks (Squalidae), bonefish (Albulidae), croackers, kingfish, drums (Sciaenidae), hakes and pollocks (Gadiidae), rockfish (Scorpaenidae), wrasses (Labridae), butterflyfish and angelfish, Parrotfish (Scaridae), filefish and triggerfish (Balistidae), trunkfish (Ostraciidae), puffers (Tetraodontidae), porcupinefish (Diodontidae), and kelpfish (Gibbonsia) that migrate back and forth to the outer littoral zone and Coral Reefs, and to which fish diversity from this sublittoral zone is somehow related
Coral reefs are a separate development that occurs in warm tropical oceans and connects the sublittoral and littoral zones.
Coral reefs and atolls, which are the epitome of a diverse marine population, including many little fishes, are home to the majority of fish diversity found in shallow oceans.
Coral reefs can be found primarily in the Indian and Western Pacific oceans, as well as the Caribbean and the West Indies.
Due to its physical structure and spatial coral groupings, coral reefs provide a wide variety of habitats.
Despite this, there is a significant variance in the number of coral reef fish species found in different places, ranging from the Philippines’ richest central Indo-West Pacific reefs, which have over 2000 species, to the less wealthy reefs in Florida, which have between 500 and 700 species.
Recently, an excellent investigation of reef fish speciation is shown how dispersal from a central center of origin can account for both large-scale gradients in species richness and local community structure.
Furthermore, these researchers were able to demonstrate that the Indo-Pacific Region is a major center of endemism in the Indian and Pacific Oceans and that the number of fish species decreases from the center (lower latitude) to the borders (high latitude, 30 N, 30 S), something that has previously been demonstrated for other biological groups.
An analysis of coral reef assemblages is likely to be influenced by both the diversity of corals and the complexity of the substratum.
Numerous studies have provided evidence that fish abundance and species richness are correlated with coral cover, availability of shelter, structural complexity, and biological characteristics such as territoriality.
It has been documented how nighttime hypoxia affects one of the residents of coral reefs, the Gobiodon histrio.
As a result of the fact that coral reefs can be continuously distributed over a large area, widely spaced, or patchily distributed, there is a growing amount of focus on the relationship between connectivity and the number of species, and the richness of species.
This is because this information is important for environmental management and conservation.
Because the outer sublittoral zone is somewhat less productive than the inner sublittoral zone, the circumstances for the fish life in this zone change over the seasons.
This zone is illuminated by light with a spectrum that extends from blue to violet, which further inhibits the production that may take place within it.
The fish population is not very abundant and consists of species such as haddock, cod, hake, halibut, chimaera, hagfish, and eel.
Beyond this point lies the abyssal zone, which is largely stable, dark, and chilly even inside the tropical oceans, and features a fish life that is virtually completely undiscovered.
B. Oceanic Zone
There are over 2500 different species of fish that choose the open ocean as their home, with approximately half of those species being pelagic.
The open ocean accounts for nearly two-thirds of the earth’s surface area. The Oceanic zone is characterized by its relative uniformity; only certain regions are subject to the effects of seasonal oscillations, while other places experience variable circumstances depending on their depth.
It has a significantly lower rate of productivity in comparison to the neritic zone and the estuaries.
As was said earlier, this zone is broken up into three subzones: (1) the epipelagic zone, (2) the mesopelagic zone, and (3) the bathypelagic zone.
In point of fact, they are referring to the many strata layers of the oceans, which vary in depth as well as the amount of light that is available, and as a result, in the amount of biomass production.
1. Epipelagic Zone
This region is known as the euphotic zone, and it is the location of photosynthesis.
The primary productivity of tropical oceans ranges from 18 to 50 g.cm2, whereas the primary productivity of temperate oceans ranges from 70 to 120 g.cm2, representing a much higher primary productivity.
This is because tropical oceans have warmer water and higher solar irradiation. In point of fact, primary productivity has a tendency to rise from the equator, which is located at latitude 0, towards higher latitudes.
Primary productivity values remain more or less constant up to the tropics of cancer and Capricorn, and it reaches its highest point between this point and latitudes 60 north and 60 south.
When one examines the maps that were produced by the global CO2 survey known as the Joint Global Ocean Flux Study (JGOFS), it becomes clear that the warm equatorial Pacific Ocean is the largest continuous and natural source of CO2 to the atmosphere.
In contrast, the cold North Atlantic, North Pacific, and the Southern Ocean are important CO2 sinks.
This means that these ocean regions are places where large amounts of CO2 are physically absorbed and biologically assimilated.
Primary production, which occurs at the bottom of the food chain and is carried out by algae, is essential to the maintenance of fish life.
This condition is maintained throughout the year in tropical oceans, albeit at a relatively low level, as a direct result of the consistent temperature and solar incidence.
When compared to colder places, warm regions have a greater diversity of epipelagic fish fauna. This diversity includes a great number of species that feed on the neritic zone.
Mackerels, tuna (which move to colder waters to reproduce), sharks, marlin, and other species are among the animals that live in the epipelagic zone.
2. Mesopelagic Zone
The inhabitants of the mesopelagic zone, which is often referred to as the twilight zone, are dependent on the plankton and other carcasses that fall from the epipelagic zone.
During the night, many of the fish species that live in this zone move upwards to feed in the higher zone, and then they sink back down before morning.
They have evolved to the darkness, to conserve energy because there is a limited supply of food, and to the pressure, because the pressure rises by one atmosphere for every 10 meters that are dived deeper.
In general, as depth increases, the size of fish, the amount of fish, and the diversity of fish all decrease. It is not well understood what kinds of fish can be found in the mesopelagic zone of tropical waters.
Figueiredo et al. (2002) collected a total of 28,357 specimens belonging to 185 species, 84 Families, and 19 Orders while conducting research on the fishes of the southern Atlantic Ocean within 200 nautical miles of the Brazilian coast using pelagic trawling.
This research was conducted between Cabo de Sa o Tome’ (22 S) and Arroio do Chu’ (34 S), and it took place between 22 and 34 South.
In spite of the type of gear that was utilized, 86 percent of the families that were sampled had representatives that inhabited the epi and/or mesopelagic zone, while only 14 percent of the families inhabited the meso and/or bathypelagic zone.
3. Bathypelagic Zone
This zone’s inhabitants are completely reliant on food from the zones above them. High pressure, darkness, food scarcity, and the energy economy are all adaptations that animals have. Bioluminescence is found in almost all animals.
Fish numbers and diversity are drastically reduced. Surprisingly, all five strictly bathypelagic species found off the coast of Brazil have a wide geographic distribution. Bioluminescent organs were present in all of the specimens collected.
I hope you enjoying reading this article about different types of Tropical Marine environments.
A place where sea salt water and fresh water from a stream mix together to form an estuary is called an “intertidal zone.”
The definition of an estuary was proposed by Cameron and Pritchard (1963), which states that an estuary is a semi-enclosed coastal body of water that has a free connection with the open sea and within which seawater is measurably diluted with fresh water derived from land drainage, is the definition that is the most common and widely used today.
However, because estuaries are only considered to be semi-enclosed bodies of water by the authors, they fail to acknowledge the salinity gradient that is produced as a result of the interaction between the two different types of fluids and extends out from the land masses.
To put it another way, Cameron and Pritchard’s definition does not take into account the fact that the Amazon River and the Mississippi River both empty into estuaries.
An estuary may be seen as an ecotone in terms of its functional characteristics, and as such, it encompasses the margins of the salinity gradient in both the upstream and open ocean environments.
The tropics are home to the majority of the world’s most important estuaries, including the Amazon, Orinoco, Congo, Zambezi, Niger, Ganges, and Mekong rivers.
These are all extremely huge rivers that drain extremely wide geographical areas. The Amazon River is responsible for the discharge of twenty percent of all freshwater that enters the oceans around the world.
With a flow of 0.2 Sv, the Amazon River is primarily responsible for the high levels of salinity that are found near the surface of the western tropical Atlantic Ocean.
In fact, tropical estuary habitats consist of both lacustrine water basins that are occasionally linked to the sea as well as streams that only run seasonally.
The chemical, physical, and biological characteristics of these tropical estuaries are anything from homogeneous, and they have a significant amount of effect on the estuarine life, particularly the fish species.
In general, estuaries are distinguished by dramatic shifts in salinity, tidal and stream current turbulence, turbidity, and siltation.
There is no other kind of water system that goes through the kinds of dramatic seasonal changes that are seen in tropical estuaries.
In addition, estuaries that are surrounded on either side by cities (13 of the 16 major cities in the world are located on the coast) or industries may also be subjected to extremely high levels of pollution.
Estuaries in tropical regions can be roughly classified into the following four subtypes: (a) open estuaries; (b) estuarine coastal waters; (c) coastal lakes, and (d) blind estuaries. (a) Open Estuaries Open estuaries are characterized by the presence of large bodies of water that are not enclosed by land.
1. Open Estuaries
There are open estuaries formed by all medium and large tropical rivers that drain into the ocean, and among these are all of the well-known tropical estuaries that were mentioned above.
They are never cut off from the ocean and are subjected to all of the most significant environmental estuarine oscillations.
These river-mouth estuaries display layering, in which freshwater lies on top of salt water that lies underneath it, and this layering may stretch for significant distances, as was discovered for the Amazon River (also known as the “Pororoca”).
The different water levels may be home to their own unique ichthyofauna and may act as a pathway for fishes that migrate between saltwater and freshwater environments, as is the case with elasmobranches, which may be discovered in the middle of the Amazon River, not far from Manaus.
2. Estuarine Coastal Waters
Up to 400 kilometers (250 miles) from the mouth of the Amazon River, people can feel the impacts of the Amazon River’s drainage into the Atlantic Ocean.
This distance is determined by a number of factors, including tidal cycles and seasonal fluctuations in the water level of the river.
There are several other major and minor rivers, such as the Orinoco in Venezuela, the Ganges in India, and the Parana, that are affected in a manner analogous to this, and it can be challenging to delineate the limits of such ecosystems in general.
In terms of the fish species, these tropical waters can only be classified as estuarine to a limited extent because of their shallow depths, reduced salinities, and significant levels of sedimentation.
3. Coastal Lakes
Lacustrine bodies found behind tropical shorelines are referred to as coastal lakes or coastal lagoons. Coastal lakes go by both names. What distinguishes them from other bodies of water is the fact that they are rather sizable.
They are subject to substantial seasonal variation, which, in the end, defines the shape and regularity of the link between the lake and the sea.
There have been identified four primary kinds of lakes, including silled lakes, lagoonal inlets, isolated lakes, and percolation lakes. Depending on the level of salt in the water, its fish fauna includes both marine and estuarine species.
4. Blind Estuaries
Blind estuaries are often short in length and have a limited catchment area because a sandbank is placed across the estuary’s opening to the ocean.
When it is closed, fresh water from the river is able to enter the system and fill it up. The salinity is affected by tide patterns, the amount of fresh water that enters the system, the pace at which sandbanks drain, and wind speed.
In most cases, blind estuaries are utilized for human subsistence activities. Without a question, tropical estuaries are among the most intricate and changeable aquatic ecosystems there are.
They are among the most prolific ecosystems and provide a significant contribution to the preservation of marine life.
Additionally, estuaries are the breeding grounds for a great number of significant fisheries, many of which are dependent on one of the components of the estuary, which is the mangroves.
The trees and shrubs that makeup mangroves are able to thrive in salty, warm conditions and grow in shallow water. The mangroves’ murky waters are full of nutrients and provide a safe haven for a wide variety of marine species.
A new study has demonstrated that mangrove forests in the Caribbean are unexpectedly vital for the coral reefs that are located nearby.
The border of virtually all tropical estuaries is dominated by mangrove forests, making up one-fourth of the world’s tropical coastline.
I hope you enjoyed reading this article about different types of Tropical Marine environments.