Estacion Biologica Laguna de Apoyo in El Nuevo Diario

The volcanic crater lakes of Nicaragua were once again the subject of a news article in El Nuevo Diario this week. Anyone who has visited the volcanic crater lakes of Nicaragua would agree that they are quite unique. As a group, they are isolated lakes, without any open water channel connecting any of them to any other water body. Their connection through the water table, with slow filtering of water through the sediments and rocks which eliminates the passage of animals and even microorganisms to and from each lake.

GAIA has been active in studying and protecting the fauna and flora of Laguna de Apoyo Nature Reserve. 

It is precisely this isolation that makes the volcanic crater lakes of particular importance to the study of biodiversity and evolution, and consequently, gives them priority as objects of protection for the conservation of the unique fauna in each lake. The majority of the volcanic crater lakes in Nicaragua have been studied to determine what fish species are found in them. The principal study which documented these lakes was conducted by our group in eight of the volcanic crater lakes, resulting in twenty new distributional records for fish in the country. Prior work had been performed by Jaime Villa, Padre Ignacio Astorqui, and George Barlow, all of whom had conducted some amount of fish studies in one or more volcanic crater lakes.

Each of these eight lakes that have been studied contain unique fauna. Laguna de Apoyo, for instance, is the only wild habitat in the world for six species of fish; Laguna de Xiloa, for another five species. The other, less well-studied lakes on this list, definitely contain unique fish species, as well.

A former employee of our group has more recently sounded the call to name the volcanic crater lakes, collectively, a World Heritage Site, through UNESCO. This idea is not new; in fact, it has been floated repeatedly for the past twenty or so years. While some people host press conferences to hijack ideas for their personal aggrandizement, we are busy doing the things that protect the natural areas of Nicaragua and the biodiversity at risk found in them. For years, GAIA has been on the front lines of defense of the lakes from senseless destruction of the natural resource base in these fragile ecosystems. Although many of the actions go unnoticed by the public, a few have had a larger profile. For instance, GAIA director Jeffrey McCrary served as the coordinator for the development and approval of the official management plan for the Laguna de Apoyo Nature Reserve. The majority of the entries in this blog deal with the activities of GAIA inside that protected area, although several entries deal with other volcanic crater lakes, as well. In summary, we have been there, advocating for the protection of each of these jewels, with real actions resulting in new knowledge and better policy and protection.

In places like Nicaragua, it is easy to find people who want to be in the spotlight, especially foreigners who jet around from country to country, who talk about peace, or saving children from poverty, or the environment. Sometimes, such as in this example, there is not much behind their grandstanding. The real struggle is not about press conferences with grand proposals, but rather, in the trenches, building schools for poor people, spending countless hours dedicated to community involvement in the decision-making processes for natural resource use and protection, and sleepless nights in the thankless job of making a few hours in the forest or under the water turn into peer-reviewed, accepted research publications that provide meaningful justification to protect special places such as the volcanic crater lakes of Nicaragua.

GAIA is present and active in Laguna de Apoyo Nature Reserve. 

It was not lost on us that someone would discuss the volcanic crater lakes of Nicaragua in the press as if there were no current and historic initiatives to protect them, and even less surprising that it would come from a foreigner who feels the need to plant himself as protagonist in an effort that needs him to accomplish something that no one in Nicaragua could accomplish without his grandeur. It is absurd to think that someone would propose research stations in these natural areas, as if no research had ever been conducted and published already. We have come accustomed to this type of attitude, and we continue to do what we do, as small as it may seem at times. Our organization, unlike other supposed organizations, is real, solvent, and active. We are in constant communication with the communities where we have alliances and with the relevant institutions of government to assure that what we do is appropriate on all levels.

We invite you to visit us at Estacion Biologica Laguna de Apoyo or write us and get to know us. We seek alliances of all kinds, to work hand in hand wherever possible, to keep nature wild and free in Nicaragua. Please contact us!

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Cichlids of Laguna de Apoyo by Willem Heijns

People are always asking what is to see in Laguna de Apoyo during a SCUBA dive. Lots of folks have Open Water certifications these days, but most of them have only dived in tropical oceans, over coral reefs where brightly colored fish dazzle. Tropical coral reefs are indeed among the best eye candy on the planet. But people are intrigued when they learn that we SCUBA dive in tropical lakes when the ocean is so close. It's obvious to them that something very attractive must be going on down there to keep our attention, with coral reefs just a couple of hours away.

We at FUNDECI/GAIA study the fish in this lake and in other freshwater locations in Nicaragua. Lake Apoyo has clear, warm water (28 degrees C) which makes it easy to view the fish underwater. Our divers have been collecting data on the fishes of Lake Apoyo for years, learning about the differences between very recently evolved species and even documenting the species themselves. Over the years, other research groups have also become interested in the cichlid fishes of Lake Apoyo and neighboring lakes, especially the group headed by Axel Meyer of the University of Konstanz.

The fish of the Midas cichlid group are definitely the main attraction in Laguna de Apoyo. Since the lake was formed some 23,000 years ago, the lake has been colonized by a few species of fish, but the dearth of species in the lake has left numerous, broad niches available for specialization in feeding, refuge behavior, and nesting activity. The Midas cichlids in the lake have undergone a remarkable evolution, dividing into numerous species. Six species from this group which are only found in Laguna de Apoyo are now accepted in the scientific community. Publications which present these six species can be found here, here, and here. These cichlids are terribly similar, but they do not interbreed, and they even use different timing and locations for nesting in the lake. 

The video presented above, produced by Willem Heijns, is among the best quality of videos showing some of these species in their natural habitat. We hope you enjoy seeing this video. Thank you, Willem!

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You can help us keep nature wild in Nicaragua, by volunteering your time with us or making a small donation to support our projects in wild nature conservation.

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Under the water

We spend hundreds of hours per year under the water in Laguna de Apoyo, in counts of fish, documentation of the quality of the habitat where they live, the vegetation found there, and yes, even in retrieving the trash that folks discard which ends up all along the lake bottom. Here is a small collection of photos which show what we see when we are down there, in the most beautiful spot in Nicaragua. In the photoessay below, you can experience what one of our interns saw during a study of the fish with the director of the Gaia Program, Dr. Jeffrey McCrary. Dr. McCrary is leading an international team in the study of the fishes of Laguna de Apoyo, and to date five new species have been discovered as part of the program. 

These fry of an Amphilophus zaliosus pair recently hatched in a nest hole which is often seen with babies. 

Lots of fish are hanging out in this site, including a probable male Amphilophus zaliosus in breeding coloration in the center of the photo. 

Counting fish along a transect.

Juveniles and nonbreeding adult Amphilophus seek refuge under rocks in Laguna de Apoyo.

Breeding season is approaching, and breeding pairs are forming. A pair of Amphilophus zaliosus are in the foreground, and a pair of jaguar cichlids, Parachromis managuensis, are in the background. 

As can be seen from the photos, several Midas cichlid species are locally abundant in the waters of Laguna de Apoyo. Of the six species recognized in Laguna de Apoyo in this group, the most abundant of the group in most locations is the little Apoyo cichlid, Amphilophus astorquii. Other fish species are in the lake, too: Atherinella sardina, Poecilia sphenops, and Parachromis managuensis, as well as some invasive species.

Fish ahead!

A multispecies school of Amphilophus cichlids.

The species of Amphilophus cichlids in Laguna de Apoyo vary by body shape, spot pattern, and background colors. 

Dozens of cichlids are always under this rock!

Much of the lake bottom is covered with recently eroded sediments which cover the rocks and destroy all the high-quality habitat. Furthermore, ordinary garbage accumulates along our transects, such as this plastic cup, sold by the local bars. 

In some areas where waves clean the substrate, the lake bottom is covered with fine mud or sand. 

Fragments of snail shells (Pyrgophorus coronatus) litter the surface in many places. Snails are an important component of the diets of the Amphilophus species flock in Laguna de Apoyo. 

Filamentous algae has displaced Chara vegetation along the bottom in much of the lake. We do not understand why Chara often disappears from the lake, although it is known that tilapia will consume large quantities of it. 

In shallow areas with small rocks, juveniles of the invasive species Gobiomorus dormitor abound. 

Many shallow areas are covered with snail shell fragments, demonstrating the abundance of snails in Laguna de Apoyo.

A human-altered waterscape in Laguna de Apoyo. Filamentous algae and a plastic beverage bottle displace native fish and vegetation. 

Silversides, Atherinella sardina, put on a show in the water column. Silverside schools may exceed ten thousand individuals. 

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SCUBA diving in Lake Apoyo, Nicaragua

Hundreds of young arrow cichlids (Amphilophus zaliosus) are only perhaps sixty days from hatching. Although they have been abandoned by their parents, they continue to school at a nesting site. Photo by Martin Cabrera.

We often get asked what can be seen while SCUBA diving in Laguna de Apoyo. Nicaragua has lots of lakes and rives, but most tropical freshwater sites here and elsewhere have low visibility. Lake Apoyo visibility is almost always 5-12 meters at the locations where we dive.

The fish of Lake Apoyo are special, too. The most commonly seen fish are members of the Midas cichlid species complex. Six species in this group have been discovered  in Lake Apoyo, all of which evolved in the lake and inhabit only this lake. The first to be discovered was the arrow cichlid (Amphilophus zaliosus) in 1976 by a professor at University of California-Berkeley, George W. Barlow. Most of these six endemic species can be seen while scuba diving.

Arrow cichlids, like all the other members of the Midas cichlid species complex in Lake Apoyo, nest in rocky reefs, but they also nest often over sandy bottoms in water from 4 to 8 m depth. All the fish in this species complex, which is found throughout the San Juan River watershed and a few rivers to the north and south, provide parental care to their fry for several weeks after hatching. Here is a photo of the arrow cichlid fry after the parents have abandoned them. These fish are no longer defended from predation by the parental units. 

These arrow cichlids have not yet dispersed but are no longer receiving parental care. Photo by Martin Cabrera. 

The parental units expend a lot of energy during the seven weeks of care of the fry. Predators constantly attempt to capture the small fish and they are fended off by the parental units. It's a long seven weeks, not including the courtship and egg-incubation. Parental units often look battered and even emaciated at the end of the period of parental care. However, the great majority of nests never make it to seven weeks fry age, because predation and disease will have killed of the entirety of their nests.

After a scuba dive in Laguna de Apoyo, the clearest lake in Nicaragua. Photo by Martin Cabrera.

Lake Apoyo is the easiest of all locations for scuba diving in Nicaragua. We are located only one hour from downtown Managua. Estacion Biologica collects data at four sites in Laguna de Apoyo, all have easy reach from the shore, and great views below. We enter our study areas from the shore, along property managed by Estacion Biologica.

Life is good after a dive. Photo by Martin Cabrera.

One vital reason for our monitoring program is the bigmouth sleeper, Gobiomorus dormitor. This fish looks a lot like a goby, only much larger as an adult. This voracious predator sits quietly on the lake bottom, where it awaits an injudicious move by any appropriately sized fish, when it strikes with lightning speed. The fish of Lake Apoyo spent thousands of years without the threat of bigmouth sleepers or anything similar, so they are now evolutionarily naive to the grave threats this fish presents.

The Bigmouth Sleeper (Gobiomorus dormitor) is a dangerous predator. It was introduced into Lake Apoyo in 1991. Photo by Martin Cabrera. 

Bright blotches, usually randomly placed, are not exactly uncommon among fish. These colors are usually caused by a specific mutation, such as in the goldfish, which is simply a selectively bred variant of a wild carp. Midas cichlids have a similarly brightly colored variation in the wild, although the "golds" are much more common in some locations than in others. Lake Apoyo, for instance, is considered to have no gold forms. Nonetheless, as the photo below demonstrates, gold forms may also be found in Lake Apoyo.

Gold form Midas cichlids are relatively common in some lakes, but not in Lake Apoyo. Fish such as the one in this photo are exceedingly rare. Photo by Martin Cabrera. 

Which gene(s) control the gold color form in the Midas cichlids is not known. Nor does anyone understand why Lake Apoyo has so few golds. In comparison to most other natural habitats of the Midas cichlids, Lake Apoyo has far fewer golds.

Some Midas cichlids show 

This clownish coloration is quite common among Midas cichlids in Lake Managua, some parts of Lake Nicaragua, and other volcanic crater lakes such as Lake Masaya and Lake Xiloa. Why is it so rare in Lake Apoyo? We don't know.

This breeding, gold form Midas cichlid stays near the nesting hole. Photo by Martin Cabrera.

Midas cichlids are territorial when nesting. A breeding pair will occupy a natural or constructed hole, often at the base of rocks, in which a hard, flat, usually vertical surface can be utilized to adhere eggs. The pair will defend the site vigorously against predators and usurpers.

The gold-normal breeding pair linger near the nesting cavity. Photo by Martin Cabrera. 

The great majority of Midas cichlid nests do not result in the eventual creation of new adults. Hundreds of eggs are produced in each spawning, but very few fry will reach the age to swim away from the parental units and begin life independently of them.

The Bigmouth Sleeper has occupied Lake Apoyo only two decades, but is now very common. Photo by Martin Cabrera.

The newest reason for the demise of nests in Lake Apoyo, the bigmouth sleeper, has become very common in the lake. Some of the Midas cichlid species of Lake Apoyo are so rare that the bigmouth sleeper could even make the species disappear. Who would even know if a fish species in Lake Apoyo went extinct?

Filamentous algae forms a carpet on the lake bottom where Chara macroalgae was once abundant, placing much of the life in the lake at risk. Photo by Martin Cabrera. 

The bigmouth sleeper has a neutrally colored, mottled pattern along its sides and back, making its detection difficult. It sits on the bottom, awaiting a false move by some other fish. It strikes rapidly, with the intention to sink its long, fine teeth into the prey and then gradually move the prey into the mouth to swallow it.

A Bigmouth Sleeper (Gobiomorus dormitor) pair in courtship in Laguna de Apoyo. Photo by Martin Cabrera. 

The success of bigmouth sleeper (Gobiomorus dormitor) during the two decades of its time in Lake Apoyo is startling. They are extremely common. Recent research conducted by Topi Lehtonen and the research team at FUNDECI/GAIA demonstrated that the Midas cichlids of Lake Apoyo do not recognize the threat these fish present to their fry.

These Midas cichlid fry must share their nest space with garbage left by humans. Photo by Martin Cabrera.

Lake Apoyo's fish species are facing several threats from humans. Soil introduction into the lake is higher than ever, coming from constructions in the watershed. Predation and loss of habitat by introduced species have done lots of damage to the species found here. And of course, garbage follows humans everywhere we go. The fish of Lake Apoyo have no choice but to utilize garbage-filled areas of the lake to feed and reproduce.

Juvenile Amphilophus cichlids in Lake Apoyo, Nicaragua. Photo by Martin Cabrera. 

Lots of juvenile Midas cichlids are present year-round in Lake Apoyo. By diving during the different seasons, one can see the smaller fish grow and, by the end of about a year, start their first anniversary as members of the next breeding stock. The intense uses (and misuses) of Lake Apoyo by human beings requires that we assure adequate habitat for these fishes in all their life stages.

A blind Amphilophus astorquii in Lake Apoyo, Nicaragua. Photo by Martin Cabrera.

To date, six species of the Midas cichlid species complex have been described in Lake Apoyo. All of them are only found in this lake. There are eight volcanic crater lakes such as Lake Apoyo, near the Nicaraguan Great Lakes, which have multiple species of Midas cichlids in them. What was once thought to be only one or a few species is now considered to be dozens of species, with very small ranges, and in some cases, populations of only a few thousands of adults. One of those species with a very small population is the chancho cichlid, Amphilophus chancho. It is the largest of the Midas cichlid species complex found in Lake Apoyo, with males sometimes reaching well over a kilogram weight.

Amphilophus chancho defending fry in a nesting hole in Lake Apoyo. Photo by Martin Cabrera. 

Child-rearing is an expensive venture for most species. It is especially so for the Midas cichlid species of Lake Apoyo, too. Providing care for the fry means eating less and lower quality food. It also means getting in harm's way. The parental units must confront potential predators and utilize displays, threats, and if nothing else works, direct attacks to drive away the fish and crabs that would want to eat the fry. Adults often look emaciated and battered at the end of the breeding season.

Amphilophus fishes near a hole beneath a rock in Lake Apoyo, Nicaragua. Photo by Martin Cabrera.

A scuba dive with the staff at FUNDECI/GAIA usually means seeing most of the six species of the Midas cichlid species complex, perhaps about five hundred individuals in total. Occasionally, we get to see jaguar cichlids (Parachromis managuensis) up close, while nesting. It also means seeing the ubiquitous bigmouth sleeper, lots of them, perhaps upward of a hundred individuals in a single dive. Other fish, crabs, and the dramatic undwater views round out most dives. Some of the dives take you to thermal vents, where clear, warm water flows from between rocks into the lake. And especially during the appropriate season (November through February), lots of fry in nests!

An adult bigmouth sleeper uses a hole beneath a rock as a hiding spot, from which to hunt. Photo by Martin Cabrera.

Diving in Lake Apoyo is different than in the ocean and generally much easier. No currents, waves, poisonous animals produce dangers here. The dives are rewarding and especially so when contemplating the rarity of some of the fishes, to which our divers contribute to study and protect them. Please contact us if you would like to dive with us in Lake Apoyo.

Jaguar cichlid (Parachromis managuensis) fry are feeding in open water outside their nest cavity in Lake Apoyo, Nicaragua. A small clump of Chara vegetation can be seen in the lower left. 

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Dive Laguna de Apoyo

Let's get in the water! Photo by Kim Bracken.

Most people who SCUBA dive have experience in the ocean. But diving in a tropical lake is a unique experience, especially when diving in Lake Apoyo. Its water is too salty to be potable, however it is still near the buoyancy of freshwater. Lakes differ from the ocean, too, in smaller waves and currents, and fewer dangerous animals. Lake Apoyo has essentially no moving water, making the dives easily managed. No fish or other animals in Lake Apoyo sting or bite!

Lake Apoyo is not just a freshwater lake, however. It is a volcanic crater lake, occupying a huge volcanic caldera between Volcano Masaya to the north and Volcano Mombacho to the south along the string of volcanoes across the Pacific side of Nicaragua. Because the Apoyo volcano is mostly a hole, however, the lake is its most prominent feature.

Divers discuss their dive plan before heading down. Photo by Kim Bracken.

FUNDECI/GAIA coordinates SCUBA dives in Lake Apoyo, where you can accompany scientists in their study of the fishes. Each month, our divers review fish populations in several habitats, and visiting divers can join us on our dives. Divers get to see many species of fish in a single dive, and learn how these fish live, breed, and how we are working to protect them.

Not so many fish species occupy Lake Apoyo: only jaguar cichlids (Parachromis managuensis), mollies (Poecilia sphenops), silversides (Atherinella sardina), and several members of the Midas cichlid species complex (Amphilophus cf. citrinellus) are considered native. These fish populations probably got their start in Lake Apoyo by hurricanes, birds, or even the precolombian human populations that could have brought some individuals from Lake Nicaragua, just four kilometers to the east.

Several endemic fish species from the Amphilophus species flock occupy Lake Apoyo. The research group at GAIA has discovered five species to date. Photo by Balasz Lerner.

The Midas cichlid population of Lake Apoyo has attracted the attention of scientists for many years, and has been the principal cause behind the studies we pursue. In 1976, George Barlow began the current trajectory of interest in Lake Apoyo by declaring the arrow cichlid (Amphilophus zaliosus), as a new species. This lake is among the best study sites in the world for sympatric speciation among animals. 

Our group at Estación Biológica has studied these fascinating fish several years. In 2002, we published the official description of three new species in Lake Xiloa. Then in 2008, we published another set of species descriptions, giving official names to three species in Lake Apoyo. In 2010, we then followed with two more species descriptions in Lake Apoyo among the Midas cichlid species group. 

Our ecological studies in two lakes, Apoyo and Xiloa, where we have also performed several years of monitoring, are essential to the Midas cichlid species discoveries. Without being in the water, observing the fish month after month, we would never have been able to distinguish these very similar and closely related species. Our monitoring program has given us a wealth of information which is behind the species discoveries and several other new findings. 

The members of the Midas cichlid species complex found in Laguna de Apoyo are: 

Amphilophus astorquii

Amphilophus chancho

Amphilophus flaveolus

Amphilophus globosus

Amphilophus supercilius

Amphilophus zaliosus

These six species are elegantly displayed on our new Laguna de Apoyo t-shirts-please purchase one and support nature research in Laguna de Apoyo!

Among the more common fish in Lake Apoyo today is the Bigmouth Sleeper (Gobiomorus dormitor). This fish was introduced to Lake Apoyo in 1991, and its population has grown dramatically. We at GAIA are studying the impacts of this introduced fish on the native species of Lake Apoyo. Photo by Wito Lapinski. 

The fish of Lake Apoyo are not just some rare novelties. They are facing some serious threats to their continued existence. One of the threats comes from introduced, invasive fish species. On a few occasions, tilapias have been introduced, most notably, in the 1990's as part of an aquaculture experiment using the Nile tilapia (Oreochromis niloticus). This misguided, disastrous activity was conducted with the approval and participation of the Ministry of Natural Resources and the Environment during that period. At the time, tilapia was touted by some influential individuals in Nicaragua as an economic "silver bullet" which would make investors rich and would feed poor people, as a kind of pinnacle to the Blue Revolution. The issue of environmental and health impacts of improper tilapia aquaculture methods in Nicaragua was recently featured in the New York Times. Many ripostes followed, too!

In 1991, an over-enthusiastic local fisherman added to the mix in Lake Apoyo, by bringing a bucketful of bigmouth sleepers (Gobiomorus dormitor) he had just caught from another, nearby lake, to Lake Apoyo and dumping them in. A few fish quickly became thousands and today this fish is ubiquitous. The threats this fish poses to Lake Apoyo's endemic species is magnified by their loss of sensitivity to the dramatic threat the bigmouth sleepers pose to their fry. The research team at GAIA worked with scientists from Finland and Germany to demonstrate the evolutionary naivete to fry predation by the introduced bigmouth sleepers in a 2012 publication.

We also coordinate underwater lake cleanups periodically, our third one was performed in 2011. 

After collecting data, a relaxing moment by the pier is in order! Photo by Kim Bracken.

Would you like to dive with us in Lake Apoyo? We would be happy to schedule a dive with you. You must have the equivalent of an open water certification. We can provide all the equipment and you can help us in our research on these very special fish.

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