Jaguar cichlid in Laguna de Apoyo, Nicaragua

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Many cichlid fish species evolved in the Nicaraguan Great Lakes system. Among the more popular of the fish of this region are the guapotes, fish of the genus Parachromis. Guapotes can make a very nice fish dinner. The most abundant of the guapotes in the San Juan River and the Nicaraguan Great Lakes is the Jaguar cichlid, Parachromis managuensis. In Nicaragua, it is known as the guapote barcino, in reference to its checkerboard spotted pattern. Along with several species from the Midas cichlid species complex, the Jaguar cichlid make nests in which parental care observations can be made easily during SCUBA diving.

All the mating cichlids native to Nicaragua protect their young for several weeks after hatching. The guapotes have some important structural advantages to parental care over the more common Midas cichlids found in their range. First of all, the guapotes are large, and therefore can sustain large egg loads. It is not uncommon to see over 2000 fry at Jaguar cichlid nest. Secondly, the guapotes all have large mouths adapted to capture fast-swimming fishes. A bite of the Jaguar cichlid could be fatal even to a medium-sized fish. Potential predators know this and tend to avoid the risk of a bad bite.

These hatchling Jaguar cichlids are less than a week old. They stay near the parental units within reach of a natural or dug cave, and they receive parental care up to about 60 days after hatching. Photo by Martin Cabrera. 

Along with several bird species, the Jaguar cichlid sits atop the food web in Lake Apoyo, Nicaragua. It is the only fish in the lake that can kill and consume up to medium-size fish. Adult Jaguar cichlids only eat fish and perhaps crabs.

Hatchling P. managuensis are prone to move toward the diver, a camera, a hand. Photo by Martin Cabrera.

Male Jaguar cichlids differ morphologically from females in its upturned mouth and other aspects of head shape. Like all the other cichlids native to Nicaragua, the males in breeding pairs always exceed the females in size.

This female Jaguar cichlid is never far from her free-swimming fry. Photo by Martin Cabrera.

All cichlid nests can be fascinating, and the Jaguar cichlids are not unique in this respect. Parents may move little in defense of their fry, but they usually don't have to do much, to get the point across to potential predators.

Most cichlids in Nicaragua utilize natural features such as caves and holes to defend their offspring. This Jaguar cichlid is watching her fry just outside of this crevice. Photo by Martin Cabrera.

Breeding seasonality of the Jaguar cichlid is not as strong as in the Midas cichlids in Lake Apoyo. Whereas the Midas cichlids may reproduce in only two to four months during the year, the Jaguar cichlid is found in reproduction most of the year.

A female Jaguar cichlid (P. managuensis) in her nesting site. Photo by Martin Cabrera.

All cichlid fishes in Nicaragua provide extensive parental care to their fry for the first several weeks after they hatch. There is fierce competition among the Jaguar cichlids for high-quality breeding sites such as this one in our photographs. This site is actually a cave under a large rock, with openings on both ends. The male parent of this nest has little or no continued relation with the nest, however. Big male P. managuensis are scarce, and the males tend to abandon nests earlier than the female, in contrast with many other Nicaraguan cichlids. Big males are easily harpooned when on nest, and unscrupulous SCUBA divers often harvest this fish, as a trophy and for a great meal.

This female is emaciated from the physical stress and reduced food intake associated with reproduction. Photo by Martin Cabrera.

Fry feed on detritus and phytoplankton/zooplankton. They stay close to their fellow fry at all times, depending on the maxim safety in numbers. Among the most dangerous predators of cichlid fry are the Bigmouth Sleepers (Gobiomorus dormitor), introduced into Lake Apoyo only 22 years ago. Both adults and juveniles can catch cichlid fry, especially when a single fish has separated from the group. Fry face a much greater risk of capture when separated from their siblings.

Mother P. managuensis and her fry in Lake Apoyo, Nicaragua. Photo by Martin Cabrera.

We at FUNDECI/GAIA are working to determine the population structure of the fishes, plants and other life in Lake Apoyo, Nicaragua. This delicate lake is under tremendous pressure from people who want to do things that affect the lake: fish unsustainably, cultivate agricultural products using agrochemicals, build houses and install grassy gardens which use copious quantities of water and leave pollution in the lake. With a population baseline, we can determine variations in populations of the different fishes and plants which may result from human-induced alterations in the lake.

This female guapote barcino tends to thousands of fry. Photo by Martin Cabrera.

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The arrow cichlid faces threats from invasive species

Lake Apoyo, Nicaragua, is home to several endemic fish species of the genus Amphilophus, members of the so-called Midas cichlid species complex, as is Lake Xiloa. Evolution may have affected the fish in these two lakes differently, however, particularly because those from Lake Xiloa evolved in the presence of an important predator of cichlid fry, the bigmouth sleeper (Gobiomorus dormitor), whereas this predator was not present in Lake Apoyo during the two hundred or so centuries during which the several species of Lake Apoyo took form. The bigmouth sleeper was introduced into Lake Apoyo in 1991, by an individual with great plans for fishing and a bucket full of the sleepers just caught in a nearby lake.

In a collaboration between the University of Turku, Finland, the University of Konstanz, Germany, and FUNDECI/GAIA, we compared the responses of two ecologically similar Amphilophus cichlids in the two lakes. The defensive responses to predators of arrow cichlid, Amphilophus zaliosus, in Lake Apoyo were compared to that of Amphilophus sagittae in Lake Xiloa. The arrow cichlid demonstrated evolutionary naivete, allowing this dangerous predator of fry to reach closer to its nest than its counterpart in Lake Xiloa. The results were just published by Topi Lehtonen, Jeffrey McCrary, and Axel Meyer, in January 2012 in PLoS One, a journal of cutting-edge biological science research.

These results are of vast importance, because the arrow cichlid is now officially an endangered species. It is listed by the IUCN as Critically Endangered. Its population is extraordinarily small, its habitat limited to Lake Apoyo, and its threats now include an exotic predator. Our monitoring of this fish, and its fellow Midas cichlid species, is more important than ever. In the context of Lake Apoyo, the bigmouth sleeper is an invasive species with dangerous qualities.

Taken from the Abstract:

" Introduced species represent one of the most serious global threats to biodiversity. In this field-based study, we assessed behavioural responses of brood tending cichlid fish to an invasive predator of their offspring. This was achieved by comparing parental defence responses of the endangered arrow cichlid (Amphilophus zaliosus), a fish species endemic to the crater lake Apoyo in Nicaragua, towards the bigmouth sleeper (Gobiomorus dormitor), a formidable predator of cichlid fry, and all other potential fish predators of offspring. The bigmouth sleeper was recently introduced into Apoyo but naturally co-exists with cichlids in a few other Nicaraguan lakes. Arrow cichlid parents allowed bigmouth sleepers to advance much closer to their fry than other predators before initiating aggressive brood defence behaviours. Interestingly, parents of a very closely related species, A. sagittae, which has coevolved with bigmouth sleepers in crater lake Xiloa´, reacted to approaching bigmouth sleepers at comparable distances as to other predators of cichlid fry. These results provide a novel demonstration of the specific mechanism (i.e. naive parental behaviour) by which invasive predators may negatively affect species that lack the adequate behavioural repertoire."

If you are interested in seeing the arrow cichlid up close and personal, go scuba diving with us. We monitor the fish populations of Laguna de Apoyo and certified open-water divers can join us in a monitoring dive.

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Intensive Course-Biodiversity of Freshwater Fishes

Estacion Biologica in Laguna de Apoyo Nature Reserve gave a course in tropical fish biology and biodiversity in 2010. The students were from US, Germany, Honduras and Nicaragua. The course was directed by Jeffrey McCrary. There were field activities in Lake Apoyo, Lake Masaya, and in two streams in La Conquista on the Pacific Coast.

Jeffrey McCrary explains morphological details for the identification of a fish from Lake Masaya. LA PRENSA.

The course covered the following topics:

1. Freshwater fish diversity in Nicaragua.
2. Taxonomy.
3. Field techniques in population and ecology of freshwater fishes.
4. Midas cichlid phylogenetics.
5. Freshwater fish ecology and conservation issues.

The little Apoyo cichlid, Amphilophus astorquii, in Laguna de Apoyo, Nicaragua. Photo by Ad Konings.

The arrow cichlid, Amphilophus zaliosus, in Laguna de Apoyo, Nicaragua. Photo by Ad Konings.

FUNDECI/GAIA periodically offers courses in wildlife management, tropical biology, and natural area management. If you would like to register for a course, please let us know!

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SCUBA diving in Laguna de Apoyo

We dive to study fish. We study fish to save them. Doubtless the fish of Laguna de Apoyo are facing a race against time as man continues to encroach on their habitat. Each day, the shores of the crater lake have fewer trees. Houses are built, forests are cut, pesticides are applied, all slowly drying and poisoning the only home for six known species of fish and countless others which have not been "discovered" officially. Dozens of fish species remain undiscovered in the waters of Nicaragua.

Here are the endemic species which have been named to date:
Amphilophus chancho
Amphilophus globosus
Amphilophus supercilius
Amphilophus flaveolus
Amphilophus astorquii
Amphilophus zaliosus

The last listed species, the arrow cichlid, was discovered by George Barlow in 1976, while the other five were discovered between 2008 and 2010 by a multinational research team in collaboration between FUNDECI/GAIA, Jay Stauffer's group at Pennsylvania State University and Matthias Geiger at Maximillian Ludwig University (Munich). They are all very closely related species, evolved since an introduction into the volcanic crater lake 10,000-20,000 years ago. All the fish are descendants of a parent Midas cichlid (Amphilophus citrinellus) stock.

In the photo below, taken while SCUBA diving on one of our monitoring sites in Laguna de Apoyo, several of the above-mentioned species are present.

A multispecies Amphilophus school in our monitoring site. Photo by Balasz Lerner.

We count fish numbers at fixed depths in specific locations monthly, as well as fish nests. The counting methods have permitted us to gain the extensive experience necessary to begin to decipher the differences between the fish species-distinctions that the fish themselves "see" but we do not nearly as easily.

Lorenzo Lopez is taking notes on fish populations in our fish monitoring activity in Laguna de Apoyo.

This study is important because it permits us to detect changes in the lake habitat and fish populations, hopefully giving us time to respond in the event of a potential fish kill or extinction event. We are still trying to understand just how many of each fish species are in the lake in order to interpret our results better. We have recently published a baseline of fish populations and breeding rates at three sites in Laguna de Apoyo, which you can find here.

Not only fish are observed in our monitoring work. We count the crabs seen as well:

Potamocarcinus nicaraguensis in Laguna de Apoyo.

Little is known about the crabs that inhabit the Nicaraguan Great Lakes system. We occasionally see them eating a dead fish, or more often, hiding in a hole or beneath an object. We usually see two or three each dive. We have begun counting them systematically, to look for trends in their population over time.

You can join us! Please let us know if you would like to dive with us in Laguna de Apoyo. If you are a certified diver, and you would like to accompany us, you can learn about the rare and threatened fishes of the lake, see them up close, and help us collect data that ultimately will contribute to scholarly publications about these fish and their habitat. We know far too little about these fish, and your participation helps us learn more about how to protect these species. We are saving Nicaraguan wild nature, and you can help.

Whether you are a field biologist or a tourist, we there are ways you can participate in our work. A few of the ways are:

1. Participate in our diving research program as a diver. Any certified diver can contribute by "buddying" on a research dive.

2. Visit us at Estacion Biologica in Laguna de Apoyo Nature Reserve and meet us personally.

3. Tell others about us and the nature conservation activities in Nicaragua.

4. Patronize businesses with responsible management practices such as permits, pesticide use, waste management, etc.

5. Volunteer some time with us-we have a constant need for volunteers outside the water as much as inside, from computer data management, conservation professional support, to physical activities without technical expertise.

6. Collaborate with us as a visiting scientist. We have numerous projects and topics that could benefit from the involvement of more researchers. Our group publishes more than any research group in Nicaragua, and we would like to work with more international and local collaborators.

7. Donate-whether in cash or used dive equipment in good condition. We can get material transported from the US if necessary. We can receive financial donations via paypal, and provide tax information (we are a Nicaraguan registered not-for-profit).

Please contact us if you want to help. This project depends on individual, small-scale contributions, so your can make a difference.



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