Belize ecosystems

Belize is found within the tropics. The tropic is the region between the tropic of cancer and the tropic of Capricorn. More specifically Belize is found in the Neotropics which are the new world tropics (Central America, South America and the Caribbean). Between 80-90 percent of known species live within the tropics. Belize also has a wide diversity of habitats including savanna, rainforest, mangroves, and coral reefs. See the below photos, taken by yours truely, that show just some of the diversity Belize has to offer. It has one of the largest reefs in the world which is able to support a large number of species.

Within tropical forests, there are many ways in which a species can specialize. This is because a large number of nutrients and space resources are available. This type of environment can create endemic species which are species whose range is limited to a certain geographic area. When there is a high number of endemic species there is a high level of biodiversity.

In comparison to other nearby areas Belize has a high number of native forests, 65-70 percent of the country is covered by the native forest. In part this is because some areas are too remote to sustain development. Native forests are found to have greater diversity than secondary forests. A large area of the country is a part of reserves, about 26 percent of the land and sea, and 33 percent of the land. The average percent for land conserved across Latin America is 20 percent.

A savannah in Belize, captured by Lauren Schramm

Belize contains 4000 species of flowering plants, 730 tree species, and 280 orchids. Its biodiversity is high compared to the surrounding regions because of the island biogeography theory. Basically what this means is that the level of species on a landmass is contrast (but not necessarily the same species) and species richness is positively correlated with landmass size. So the greater the landmass the more species there will be. Since the Caribbean is made up of islands then there cannot be as many species as a place on the mainland like Belize.

The black orchid (Encyclia Cochleatum), the national flower of Belize, captured by Lauren Schramm

Indicator species are species that are heavily influenced by the quality of the environment in which they live. Because of this, they are often used to gauge the health of the ecosystem. Because amphibians breath through their skin they are considered an indicator species. In Belize, there are 37 species, in 10 families. In contrast, Bermuda only has 3 species of amphibians, in 2 families. This can be explained by the latitudinal diversity gradient. Belize is much closer to the equator than Bermuda and other Caribbean nations. The theory says that species richness declines the further away from the equator you move. Because there are many species in the tropics the species are often found in low abundances.

There are many theories on why diversity is high in the tropics including high speciation rate, low extinction rate, more net primary productivity, structurally complex ecosystems, and stable climate over time. In addition, there is lots of rain in the tropics which means that lots of water is available. Species like epiphytes greatly benefit from this. The environment has been stable over time so likely the species there today are similar to those in the past. However because there are a large number of species, none dominates. This means that each occurs in a low number. In areas with fewer species, there are often dominant species.

Marine ecosystems of Belize

The following post is a reflection on a field trip I took to Belize as part of my tropical ecological class. In the marine environments, there were three main ecosystems that we explored; seagrass and sand flats, coral reefs, and mangrove forests. Of all of these, the coral reefs had the highest species richness due to their high primary productivity. This is due to the dual nature of coral, that of a producer and a predator. Coral itself is a tiny animal that hunts plankton with tiny barbs. Most coral tissue also contains an algae called zooxanthellae which provides energy to the coral via photosynthesisThis creates available energy for others, like parrotfish that eat corals. It also allows the coral to create a structurally complex area. The mangroves have the next highest level of primary production and are almost as structurally complex as the coral reefs. On the other hand, the sandy and grassy flats have little structure to them. When snorkeling there very few species besides 3 species of ray were seen.

Belize contains the 2nd largest coral reef in the world and is notable for this feature called a blue hole

Mangroves are a group of woody plants that grow in areas that are exposed to salt water. The species we saw the most of were the red mangrove (Rhizophora mangle). These trees often have prop roots. The served as great habitats for a large variety of sponges. The roots were also the ideal habitats for baby fish. We saw smaller versions of many of the species we saw at the reef. The water was also slower in this area. This is important because it allows for silt to settle out, and the roots of mangroves need soft sediments to grow well. The area inside of the barrier reef is ideal for these types of environments to develop because the reef crest was able to decrease the wave action in the area. The roots were also very lightweight. This was a result of the aerenchyma tissue in the roots which are sponge-like root tissues that allow for the transportation of oxygen. The roots also provide habitats for young fish, increase friction between the wave and the tree, and trap sediments. The decrease water speed due to increased friction was very noticeable, as we traveled deeper into the mangroves the waves lessened until it was almost still.

Red mangrove trees (Rhizophora mangle)

The species richness of the coral reef appeared to be heavily affected by niche speciation in spatial terms. We saw a variety of fish that used the different spatially regions of a coral reef. The nurse sharks and rays feed on the bottom. Some fish like black hamlets (Hypoplectrus nigricans) preferred to live on the top of the coral mounds. Other larger fish like the queen angelfish (Holacanthus ciliaris) live near corals in isolated pockets. Lastly, some fish such as the squirrelfish (Holocentrus sp.) prefer to live underneath the coral mounds. Species evenness did change because the availability of certain structures was greater than others. For example, there was lots of space for black hamlets, but there were fewer isolated pockets for French angelfish (Pomacanthus paru). These are also examples of specialization which happens when a species becomes uniquely adapted to a narrow resource. This reduces competition between species in the reef which allows more species to live there.

The coral reef in some areas was clearly more subject to top-down forces than others. Often corals are in competition with algae, in the last reef we snorkeled this was partially noticeable with the brown algae growing in some areas. This is kept in check by the fish that prey on the algae in these areas. If the fish are removed then the coral will not be able to compete with the algae. The reef where the algae were seen growing was also where the local fishermen like to fish. The increase in fishing for these species has been linked to an increase in the number of algae in an area. It is possible that overfishing is or could affect the reef in this area. Many of the fish caught were served to tourist on the island so it is possible that eco-tourism could harm the reef if more fishing regulations are not put in place.

There was bleaching in some areas of the reef. Bleaching usually occurs when the temperature of the water is too great and the algae in a symbiotic relationship with the coral start to produce toxic compounds to the coral. Because of this, the coral ejects these cells, and since the cells coral the coral the coral then appears white. It is possible for a coral to survive this event but this depends on its resilience. Some species of coral are more resilient than others so the biodiversity of species is highly important. The species that appeared to be maintained the most by bleaching were the branching corals. These also were the corals that were washed up on shore the most.


The area effect was also witnessed in the reef. This says that there is increased species richness with increased area. The larger the patches of reefs the great the size of the fish, and the species richness. I would also argue that the area effect could explain why some habitats contained fewer species, particularly if you compared the available space to organisms in the reefs, mangroves and sea flats. The more surface area available the more species our class found. As the more of a type of ecosystem, we explored the more species we found. In smaller areas, there were fewer species than in larger areas.

Forest eco-systems of Belize

The following has been modified from my field notes from when I took tropical ecology and did a field session in Belize.

In the rainforest ecosystem, the number of symbiotic relationships between organisms is astounding. For example, the relationship between leafcutter ants and the fungus is highly observable in Belize. There is such a great number of these ants that paths are created by them. Leafcutter ant is a generic term for one of 47 species, in the orders  Atta and Acromyrmex. They take leafs from plants and chew them up, this plant material is then fed to a fungus, which they eat. In a sense they are farmers. Since the fungus receives a habitat and the ant receive food, this symbiotic relationship is mutualism. There is a dark side to this relationship though. If a plant is highly desirable by ants they will highly predate on said plant. Because of this, they are seen as pests by farmers, whose crops they can destroy.

Leafcutter Ants. Captured by Lauren Schramm, Belize City, Belize

We saw a wide variety of epiphytes growing on a wide range of trees. Epiphytes are plants that live on the bark and the branches of other trees. This feature allows the plant to gain access to light with a limited energy investment. Most plant growth is limited by sunlight, water availability, and temperature. They are not parasitic but their weight can damage trees. This is an example of commensal as the trees are not harmed but the epiphyte benefits from the relationship. At the Mayan ruins, we saw one plant that has adapted to solve this issue by shedding its bark, so the epiphytes fall off with the bark. This worked fairly well for the tree but in one area a plant had managed to survive on the tree. The most commonly recognized epiphytes are pitcher plants, “air plants”, and mistletoe (Santalales).

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