**Abstract**

The subterranean ecosystems in tropical areas of Mexico, North of Guatemala & Belize are very abundant because the karstic soil that allow these formations are the main composition in the Yucatán Peninsula and several mountains systems in these countries; also, they have a strong relationship with tropical forest adjacent where the main energy into the caves have an alloctonous origin. In these three countries there are three different cave conditions: a) freshwater semi-dry caves, b) flooded freshwater systems and c) anchialine systems. Mainly crustaceans and freshwater fishes are the major representative group in the aquatic diversity in these systems because the anchialine members are restricted to Yucatán Peninsula and Islands adjacent. Around 5000 entries to subterranean world there are among these countries, where the Yucatan Peninsula is the area with major caves or cenotes in comparison with southern of Mexico, North of Guatemala and Belize. Into these systems are possible found crustaceans and fishes from different families. The objective of this paper is present a review of these systems according with each karstic areas and show the current map including the location of each systems; as well their subterranean aquatic biodiversity and, finally discuss the relationships among these different areas using their biological aquatic richness in consideration with ecological subterranean conditions.

**Keywords:** Mesoamerica, Subterranean Biodiversity, Cave environments

## **1. Introduction**

The biodiversity in the tropical area among Mexico, Guatemala and Belize are good represented in several taxa since the tropical forest are the most representative biomass in this area, where there are a high species richness. The climatic conditions produce a great opportunity to maintain this diversity [1].

The geological history of Central America shows that this area is recently in comparison with the Mexican North portion, however the Peninsula Block has moved into the sea 165 Ma during the Jurassic Period, and emerge on Pleistocene; during these last period the opportunity of the migration species to colonised the mountain chains in Guatemala y Belize had origin from north to south [2].

This geological history include the karstic regions in the three countries, but the Yucatan Peninsula is the most recently portion in emerge from the sea in México [3], but the volcanic activities and emerged areas in the north of Guatemala and even Belize central portion involved the mountain formation and limestone soil, and of course the colonised caves and grootes from terrestrial and aquatic animals from surface involved species that in another times previously had occupied these epigeal environments [4, 5]. The geological conditions produce a different opportunities to be occupied for these animals mainly crustaceans and fishes [6, 7].

Has been reported the existence of different aquatic habitats in the cave environments: a) freshwater semi-dry caves, b) flooded freshwater systems and c) anchialine systems, only Guatemala have not the anchialine systems reported, but the three conditions are present in Mexico & Belize [8–16], to date is possible identify four main karstic areas: Chiapas Mountains, Yucatan Peninsula (Mexico), Alta VeraPaz karstic area, Peten Area (Guatemala), and Chiquibul area (Belize). Where fishes and crustaceans has been reported with several species. The aim of present chapter is show a review of the aquatic subterranean biodiversity in these two major taxa and their relationship with their ecological conditions that there are in each habitat type, to discuss the interrelationships that these five karstic areas.

### **2. Study area**

The study area includes the karstic regions from Tehuantepec Isthmus, Yucatán Peninsula and Islands adjacent and Guatemala & Belize. In this area exist five karstic regions 1) Chiapas karstic Mountains, 2) Yucatán Peninsula, 3) Alta Verapaz, 4) Petén Area, and 5) Chiquibul area as is possible see in the **Figure 1**.

**3. Material & methods**

**Figure 1.**

(i.e., doubletons).

**43**

Several explored trips where conducted on the last fifteen years around the study area, exploring caves and cenotes in each karstic region; according with the site was measured the abiotic data from the water (temperature, conductivity, salinity, pH, depth, dissolved oxygen and light) using the Hydrolab Data Sonde 5, applying SCUBA techniques; or the oximeter Oakton: dissolved oxygen (�0.01 mg/l), pH (�001 pH), salinity (�0.01%), and temperature of the water (�0.01°C). The altitude and the GPS values were recorded with a Garmin GPS [20–24]. With help to several speleological groups were record the GPS data from each entrance, and the photographic record of fauna has been registered. More than 100 caves were visited as representative from all regions were recorded fishes and crustaceans and preserved in alcohol to taxonomic identification, and compared with previous reports. The maps of entrance distribution to each region were done and the fauna richness relationship analysis was made according with the procedure reported for some subterranean systems [25], that "due the possibility to have a samples incomplete, some estimators have been derived to predict the true number of species based on

*Mesoamerican karstic region. Include the five study areas: a) isthmus and Chiapas Mountain systems, b) Yucatan peninsula, c) Alta Verapaz, d) Peten & e) Chiquibul and karst Main Mountain.*

*Tropical Subterranean Ecosystems in Mexico, Guatemala and Belize: A Review of Aquatic…*

*DOI: http://dx.doi.org/10.5772/intechopen.97694*

rare species in a sample. This was calculate according with Chao [26],

*S1* <sup>¼</sup> *Sobs* <sup>þ</sup> *<sup>L</sup><sup>2</sup>*

where Sobs is equal to the number of species observed in a sample, L is the number of observed species represented by a single individual (i.e., singletons), and M is the number of observed species represented by two individuals in the sample

Also the same authors recommend the application of Burnham and Overton's [27] jackknife estimators in order to reduce estimation bias in estimating species richness.

*=2M* (1)

In each area has been recorded several entrance to subterranean environments in the all them the dissolution caves are the principal formation due the limestone soil. The Chiapas karstic mountains had diverse caves record mainly dry and semi-dry conditions but in there are the most origins of superficial springs that flow to Gulf of Mexico basin [8, 9, 17]. In the Yucatán Peninsula is where there are more entrance recorded due the special efforts that involve the anchihaline systems but also there are an important number of dry cave or semi-dry caves in there in special on the Riviera Maya Coast. Also show a sub-region called Cenotes Ring where the freshwater flooded caves is very well represented [18]. Also in the Island and coast as Cozumel Island there are anchialine caves with species fauna [12–14]. Alta Verapaz region had an important Mountain Chain that produce conditions to dissolution of limestone that is the main characteristic of soil to produce different cave types from Springs as Hunalye and semi-dry caves Lanquin area where some freshwater prawns, crabs, and fishes living [19]. The highlands have an estimation of 150 Ma of age. The Petén region is the Peninsula base where the limestone starts to be the main soil type and the cave formations are frequently from Quaternary times with marine sediments [5]. Finally the Chiquibul area in the Mountain Central part of Belize but as a continuum of these soil, show a unexplored area even to discover, however in the area at less there are some caves records with important fauna [11].

*Tropical Subterranean Ecosystems in Mexico, Guatemala and Belize: A Review of Aquatic… DOI: http://dx.doi.org/10.5772/intechopen.97694*

**Figure 1.**

biomass in this area, where there are a high species richness. The climatic conditions

The geological history of Central America shows that this area is recently in comparison with the Mexican North portion, however the Peninsula Block has moved into the sea 165 Ma during the Jurassic Period, and emerge on Pleistocene; during these last period the opportunity of the migration species to colonised the mountain chains in Guatemala y Belize had origin from north to south [2].

This geological history include the karstic regions in the three countries, but the Yucatan Peninsula is the most recently portion in emerge from the sea in México [3], but the volcanic activities and emerged areas in the north of Guatemala and even Belize central portion involved the mountain formation and limestone soil, and of course the colonised caves and grootes from terrestrial and aquatic animals from surface involved species that in another times previously had occupied these epigeal environments [4, 5]. The geological conditions produce a different opportunities to be occupied for these animals mainly crustaceans and fishes [6, 7]. Has been reported the existence of different aquatic habitats in the cave environments: a) freshwater semi-dry caves, b) flooded freshwater systems and c) anchialine systems, only Guatemala have not the anchialine systems reported, but the three conditions are present in Mexico & Belize [8–16], to date is possible identify four main karstic areas: Chiapas Mountains, Yucatan Peninsula (Mexico), Alta VeraPaz karstic area, Peten Area (Guatemala), and Chiquibul area (Belize). Where fishes and crustaceans has been reported with several species. The aim of present chapter is show a review of the aquatic subterranean biodiversity in these two major taxa and their relationship with their ecological conditions that there are in each habitat type, to discuss the interrelationships that these five

The study area includes the karstic regions from Tehuantepec Isthmus, Yucatán

Peninsula and Islands adjacent and Guatemala & Belize. In this area exist five karstic regions 1) Chiapas karstic Mountains, 2) Yucatán Peninsula, 3) Alta Verapaz, 4) Petén Area, and 5) Chiquibul area as is possible see in the **Figure 1**. In each area has been recorded several entrance to subterranean environments in the all them the dissolution caves are the principal formation due the limestone soil. The Chiapas karstic mountains had diverse caves record mainly dry and semi-dry conditions but in there are the most origins of superficial springs that flow to Gulf of Mexico basin [8, 9, 17]. In the Yucatán Peninsula is where there are more entrance recorded due the special efforts that involve the anchihaline systems but also there are an important number of dry cave or semi-dry caves in there in special on the Riviera Maya Coast. Also show a sub-region called Cenotes Ring where the freshwater flooded caves is very well represented [18]. Also in the Island and coast as Cozumel Island there are anchialine caves with species fauna [12–14]. Alta Verapaz region had an important Mountain Chain that produce conditions to dissolution of limestone that is the main characteristic of soil to produce different cave types from Springs as Hunalye and semi-dry caves Lanquin area where some freshwater prawns, crabs, and fishes living [19]. The highlands have an estimation of 150 Ma of age. The Petén region is the Peninsula base where the limestone starts to be the main soil type and the cave formations are frequently from Quaternary times with marine sediments [5]. Finally the Chiquibul area in the Mountain Central part of Belize but as a continuum of these soil, show a unexplored area even to discover, however in the area at less there are some caves records with important fauna [11].

produce a great opportunity to maintain this diversity [1].

*Natural History and Ecology of Mexico and Central America*

karstic areas.

**2. Study area**

**42**

*Mesoamerican karstic region. Include the five study areas: a) isthmus and Chiapas Mountain systems, b) Yucatan peninsula, c) Alta Verapaz, d) Peten & e) Chiquibul and karst Main Mountain.*

### **3. Material & methods**

Several explored trips where conducted on the last fifteen years around the study area, exploring caves and cenotes in each karstic region; according with the site was measured the abiotic data from the water (temperature, conductivity, salinity, pH, depth, dissolved oxygen and light) using the Hydrolab Data Sonde 5, applying SCUBA techniques; or the oximeter Oakton: dissolved oxygen (�0.01 mg/l), pH (�001 pH), salinity (�0.01%), and temperature of the water (�0.01°C). The altitude and the GPS values were recorded with a Garmin GPS [20–24]. With help to several speleological groups were record the GPS data from each entrance, and the photographic record of fauna has been registered. More than 100 caves were visited as representative from all regions were recorded fishes and crustaceans and preserved in alcohol to taxonomic identification, and compared with previous reports. The maps of entrance distribution to each region were done and the fauna richness relationship analysis was made according with the procedure reported for some subterranean systems [25], that "due the possibility to have a samples incomplete, some estimators have been derived to predict the true number of species based on rare species in a sample. This was calculate according with Chao [26],

$$\mathcal{S}\_1 = \mathcal{S}\_{obs} + \left(L^2 / 2\mathcal{M}\right) \tag{1}$$

where Sobs is equal to the number of species observed in a sample, L is the number of observed species represented by a single individual (i.e., singletons), and M is the number of observed species represented by two individuals in the sample (i.e., doubletons).

Also the same authors recommend the application of Burnham and Overton's [27] jackknife estimators in order to reduce estimation bias in estimating species richness. *Natural History and Ecology of Mexico and Central America*

$$\mathbf{S}\_2 = \mathbf{S}\_{\text{obs}} + \left[ \left( \mathbf{L} \left( \mathbf{2n} - \mathbf{3} \right) / \mathbf{n} \right) \text{-} \left( \mathbf{M} \left( \mathbf{n} - \mathbf{2} \right)^2 / \mathbf{n} \left( \mathbf{n} - \mathbf{1} \right) \right) \right] \tag{2}$$

crabs *Rodriguezia adani*, *Avotrichodactylus bidens*, and *Rodriguezia* spp. (From the Ocosingo Area) (**Table 1**). In this region only the freshwater crabs was recorder from literature the remain was confirmed with our fieldtrip work.

*Procambarus mirandai Rhamdia guatemalensis* -Cosmopolitan species

*Tropical Subterranean Ecosystems in Mexico, Guatemala and Belize: A Review of Aquatic…*

*Checklist of subterranean fauna taxa of the Tehuantepec isthmus and Chiapas region all from freshwater*

*Caves and cenotes from Yucatan peninsula. The red points represent each entrance to subterranean systems.*

**Crustaceans Fishes**

*DOI: http://dx.doi.org/10.5772/intechopen.97694*

*Macrobrachium acherontium Macrobrachium sbordonii Macrobrachium* sp. (Isthmus)

*Cryphiops sbordonii Cryphiops luscus Rodriguezia adani Avotrichodactylus bidens Typhlopseudothelphusa mocinoi Typhlopseudothelphusa hyba Rodriguezia villalobosi Rodriguezia mensabak Odontothelphusa monodontis*

**Table 1.**

**Figure 3.**

**45**

*semi-dry caves.*

*Procambarus* sp. (Itshmus) *Rhamdia sbordonii*

where n is the number of samples. No direct formula for the calculation of the variance is available".
