Content
Topic Introduction
Fish are an often neglected component of tropical forest ecosystems. Fish are not important for every forest, but they play a critical role in the seasonally flooded forests that are found in Amazonia and elsewhere. In addition, some forests, such as the peat swamp forests of Asia, are flooded for much (and sometimes all) of the year. This enables permanent fish populations to be established. Forests are also important to the ecology of fish: many marine fish, for example, use mangrove forests for the juvenile stage of their life cycle, although the importance of mangroves as a nursery for fish is probably over-stated.
Fish form an important part of the diet of many other vertebrates, include mammals (e.g., otters, otter civets, fishing cats and some bats), birds (e.g., kingfishers, anhingas and cormorants, fish-eagles, fishing-owls), and reptiles (especially some snakes and predatory turtles). Some of these rely almost exclusively on fish, whereas others will take alternative prey, such as crustaceans and amphibians, opportunistically.
In permanently and seasonally flooded forests, fish play a particularly important role as both seed predators and seed dispersers. A wide variety of forms have evolved and the size of the fish often determines the size of the seed that can be eaten. Some freshwater fish can be very large: the Alligator Gar (Atractosteus spatula; Lepisosteidae) of the southern USA and Mexico reaches >3 m and 45 kg, the Arapaima (Arapaima sp.; Arapaimidae) in the Amazon Basin, reaching >3 m, the Mekong Giant Catfish (Pangasianodon gigas; Pangasiidae), reaching >3 m and >350 kg), the Zambezi Shark (Carcharhinus leucas; Carcharhinidae), and the Electric Eel (Electrophorus electricus; Gymnotidae), reaching 2 m and 44 kg. Other very large fish (>3 m, >50 kg) exist but have not been listed here.
By the end of this topic, you should be able to:
- Describe the role that fish play in the predation and dispersal of seeds.
- Explain how dispersal would occur in the absence of fish.
- Determine the roles that different types of fish play in seed dispersal.
- Draw a food web that includes both forests and fish.
- Evaluate the role of fish in the ecology of permanently and seasonally flooded forests.
Topic Readings
Required Readings
- Ghazoul, J. and Sheil, D. 2010. Tropical Rain Forest Ecology, Diversity, and Conservation. Oxford, Oxford University Press, 516 pp. Section 4.4.
Optional Readings
- Goulding, M. 1980. The Fishes and the Forest. Explorations in Amazonian Natural History. Berkeley and Los Angeles, California, USA: University of California Press. 280 pp.
- Helfman, G.S., Collette, B.B., Facey, D.E., Bowen, B.W. 2009. The Diversity of Fishes, Biology, Evolution and Ecology. Chichester, UK: Wiley-Blackwell. 720 pp.
- Nelson, J.S., Grande, T.C. and Wilson, M.V.H. 2016. Fishes of the World. 5th Hoboken, New Jersey, USA, John Wiley & Sons. 707 pp.
Further Readings
Regional Guides
Australia and New Guinea
- Allen, G.R. 1989. Freshwater Fishes of Australia. Tfh Puns Inc. 240 pp.
- Allen, G.R., Storey, A.W. and Yarrao, M. 2008. Freshwater Fishes of the Fly River, Papua New Guinea. Ok Tedi Mining. 216 pp.
- Herbert, B. and Peeters, J. Freshwater Fishes of Far North Queensland. Brisbane, Queensland, Australia: Queensland Department of Primary Industries. 74 pp.
- Pusey, B., Kennard, M., and Arthington, A. 2004. Freshwater Fishes of North-eastern Australia. Collingwood, Victoria, Australia: CSIRO Publishing. 400 pp.
- Schmida, G. 2017. Freshwater Fishes of Australia. Volume 2. Rainbowfishes, Blue-eyes, Hardyheads. Blurb.
South and Southeast Asia
- Atack, K. 2006. A Field Guide to the Fishes of Kuching Rivers, Sarawak, Malaysian Borneo. Natural History Publications Borneo. 200 pp.
- Hiware, C.J., Pawar, R.T., Gaikwad, J.M. and Sonawane, S.R. 2015. Classification and Identification of Freshwater Fishes. Daya Publishing House. 119 pp. (Deals with Maharashtra State in India).
- Hua, S.C. 2002. A Field Guide to the Fish of Tasek Bera. Ramsar Site, Pahang, Malaysia. Wetlands International Malaysia Office. 104 pp.
- Inger, R.F. and Kong, C.P. 2002. The Fresh-Water Fishes of North Borneo. Natural History Publications Borneo. 346 pp.
- Jayaram, K.C. 2010. The Freshwater Fishes of the Indian Region. 2nd Narendra Publishing House.
- Lim, K.K.P., and Ng, P.K.L. 1990. A Guide to the Freshwater Fishes of Singapore. Singapore: Singapore Science Centre. 160 pp.
- Munro, I.S.R. 2000. The Marine and Freshwater Fishes of Ceylon. Biotech Books India. 349 pp.
- Sharma, I. 2014. A Field Guide on Fishes of Himachal Pradesh. Zoological Survey of India. 112 pp.
- Singh, A.D., Abujam, S. and Das, D.N. 2018. Biodiversity of Fishes in Arunachal Himalaya. Systematics, Classification, and Taxonomic Identification. London, UK: Academic Press.
- Zakaria-Ismail, M., Fatimah, A. and Khaironizam, M.Z. 2019. Fishes of the Freshwater Ecosystems of Peninsular Malaysia. Lap Lambert Academic Publishing. 356 pp.
Africa
- Bruton, M., Merron, G. and Skelton, P.H. 2018. Fishes of the Okavango Delta & Chobe River, Botswana. Penguin Random House South Africa. 120 pp.
- Jubb, R.A. 1961. An Illustrated Guide to the Freshwater Fishes of the Zambezi River, Lake Kariba, Pungwe, Sabi, Lundi, and Limpopo Rivers. S. Manning. 171 pp.
- Skelton, P.H. 1993. A Complete Guide to the Freshwater Fishes of Southern Africa. Southern Book Publishers. 388 pp.
Central and South America
- A good account of the fish fauna of the Amazon Basin is provided by Van der Steen, P., Albert, J.S. (eds.) 2018. Field Guide to the Fishes of the Amazon, Orinoco and Guianas. Princeton, USA, and Oxford, UK: Princeton University Press. 464 pp.
- Miller, W.R., Minckley, W.L. and Norris, S.M. 2006. Freshwater Fishes of México. 1st Chicago, Illinois, USA: University of Chicago Press. 652 pp.
- Mol, J.H.A. 2012. The Freshwater Fishes of Suriname. Brill Academic Publishers, 890 pp.
- Prado, P.J., Aguirre, W., Moncayo, E.L., Amaya, R.N., Salazar, F.N., Monsalve, E.R., Hugo, E.Z., Noboa, A.T. and Rivera, J.V. Guía de Peces para Aguas Continentales en la Vertiente Occidental del Ecuador [Guide to the Freshwater Fish of Western Ecuador].Pontificia Universidad Católica del Ecuador Sede Esmeraldes. 416 pp. (In Spanish).
- Zeinad, A.K. and Prado, R. de A. Peixes Fluvias do Brasil [River Fish of Brazil]. Pescaventura. 360 pp. (In Portuguese).
Self-check Quiz
After viewing topic presentations, take this self-check quiz to check your own progress. This quiz is designed to see how well you remember some of the more important issues presented in the topic. There are five questions, and each has a potential of 4 answers, only one of which is correct. When you are ready, click the link Self-check Quiz 4.6 to start taking the quiz.
Pre-readings & Discussion (For certification)
Once you have read Section 4.4 of Ghazoul, J. and Sheil, D. 2010. Tropical Rain Forest Ecology, Diversity, and Conservation, choose to post one thought provoking question related to the material that you have read, and remember to answer/respond to at least one other student’s question on the discussion board Online Discussion Module 4.
Grade Assignment (For certification)
- There is no graded assignment associated with this topic.
Topic Summary
While rarely mentioned in forest ecology textbooks, fish can play an important role in the ecology of some tropical forests, especially those dominated by large rivers. Such rivers include the Orinoco, Amazon, Essequibo, Mekong, Congo, and Zambezi.
Fish are a source of food for a variety of vertebrates, including mammals, birds and reptiles. Fish are also predatory on other fish. In flooded forests, fish play an important role as seed predators and as seed dispersers. In the absence of fish, seeds falling into a river could only move downstream. Fish provide the opportunity for seeds to disperse upstream.
The importance of different species in seed predation and dispersal has only been established for a few areas and a limited number of fishes. Fish faunas in many tropical rivers remain poorly known, and the ecology of the individual species is even less well understood. This is an area of research with considerable potential.
Topic Self-review (For self learning)
To review what you have learned in the topic, you are encouraged to use the following reflection questions as a study guide to do a self-review for the topic:
- What role do fish play in the predation and dispersal of seeds?
- If seeds were not dispersed by fish, how would the species disperse?
- Are the differences in the types of fish that play a role in seed dispersal?
- Where would you find fish in an Amazonian forest food web?
- What roles do fish play in the ecology of permanently and seasonally flooded forests?
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