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Published online 5 February 2008 | Nature | doi:10.1038/news.2008.555
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Fish help to spread forest seeds
Catching too many tropical fish could stem the dispersal of some trees.
When it comes to studying seed dispersal in forests, mammals and birds are the usual suspects. But in Brazil's Pantanal, the largest freshwater wetlands in the world, fish have been found to have a remarkable role in distributing the seeds of tropical plants.
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This research seems to open doors for further work on unexpected ecological relationships between terrestrial and aquatic species. While Galetti and Donati show the importance of pacu for forest regeneration, one begins to wonder about all pacu food choices and how they fit in with other fish and even river otters and other elements of the Pantanal system. Once again we may rightly guess that whole system research and preservation go hand in hand.
This research seems to open doors for further work on unexpected ecological relationships between terrestrial and aquatic species. While Galetti and Donati show the importance of pacu for forest regeneration, one begins to wonder about all pacu food choices and how they fit in with other fish and even river otters and other elements of the Pantanal system. Once again we may rightly guess that whole system research and preservation go hand in hand.
This is a important report about fishing and the impact over the Pantanal Tropical Forest. Brazilian authorities should be notified about these facts in order to change the conservation law.
This is very sad because my brother loves to fish in the Pantanal. I guess we should use other "less important" fishes, I don't know. The important is to look for sustainable alternatives otherwise the Pantanal ecosystem will loose their forests.
It is very interesting to know that a fish can a play a such important role in the population dynamics of a plant species. In Brazil, other ecosystems such as the Amazon Forest, suffer a similar pattern of water flooding during the year. In this sense, we may ask if fishes are also important in the dispersal of seeds in this forest. It is possible that by understanding these relationships, it will be possible to design proper conservation plans of these areas.
That is an important paper because I suspect that many fishes outside the Pantanal basin can do the same. The problem is that most of the Brazilian river systems outside Pantanal basin are broken by hidroeletric dams, a fact that prevent fish and fruit dispersion along the rivers. Nowadays, the brazilian government wants to break the flow of the second major amazonian river(Madeira river), and I believe this will create serious damages for these fish-dispersed plants population. Nobody really knows how many frugivorous fishes persists in the Amazonian basin, and this should be investigated. This paper opens a new avenue for all this enquiries.
Galetti et al have discovered an interesting tie between aquatic and terrestrial environments. The connectivity between different media and ecosystems is important to understanding the full picture and to assessing the pressures humans assert upon them. I look forward to others following Galetti et al's lead and conducting future studies on the important connections between seemingly separate ecosystems.
This is a fascinating article and area of research, and reinforces the notion of species' interdependence. Marianne Neuwirth
Beyond the immediate lesson, of aquatic-terrestrial mutualisms, this paper highlights the capacity of transient, but regular, environments to facilitate ecological relationships among otherwise disconnected species.
Sounds that we have another trophic cascate event, where the removal of a large biomass of a key species will affect other trophic levels. The empty river syndrome mentioned in the Galetti et al. paper is a mirror of what is happening in tropical forests all over the world.
Here in China we may have the same problem, we have the highest harvesting of fishes in the rivers on Earth. I am sure that some plants that are also eaten by fishes in this area.
This is amazing how men can affect the rivers. I am vegetarian and my "ecological footprint" is low. So, I guess we all should think about eating fish as well. The cattle ranching is destroying the Amazon, and overfishing the forests...
The authors report a very important and interesting link between terrestrial and aquatic ecosystems. More studies evaluating the fishes as mutualistic fauna probably will enhance our knowledge about watershed regeneration.
This report deals with a topic of considerable interest, seed dispersal and its conservation implications. In addition, the authors provide novel information that suggest an previously unknown impact of fish harvest on forest regeneration in Pantanal. I think that future studies should investigate Amazonia and Africa, searching for similar patterns
This report make me to think the needs to add new chapter at least to add new section to refresh ours textbook of Forest Population Genentics, as one of the systematic forces of evolution. __By Jisen Shi, Professor of Forest Genetics and Biotechnology, Nanjing Forestry University, Nanjing,China 210037, jshi@njfu.edu.cn
This is a fascinating example of the potential effects of fish-mediated seed dispersal in tropical forests. Galetti et al study adds new evidence that these effects can be enormous in seasonally flooded habitats where several fish species should be considered key components of the frugivore communities. It's interesting that suppressing the largest pacu individuals can have also negative effects on seed dispersal distances of their food plants, if larger fish tend also to travel longer distances. Thus the negative effects of uncontrolled fishing can be pervasive for the demography, genetic structure and natural regeneration of fish-dependent riverine trees.
This is a very interesting study. As far as I know, it is the first to provide so many interesting details on a fish-plant system. Ichtyochory has usually been neglected in seed dispersal research, but Galleti's paper will surely encourage people to investigate the importance of fishes for plants in flooded environments. In the future, the authors or someone else could also investigate the spatial pattern of this fish-mediated seed dispersal both in flooded (like Pantanal) and 'regular' forests (Atlantic Forest areas full of rivers and streams). The 'fish effect'is surely not the same in those systems. How does the fish-mediated seed rain look like?
This is a very interesting piece of science which biologist had 'near completely' forgotten last decades: the role of fishes on seed dispersal processes on vascular plants. Although the authors are focusing on Neotropical areas, this study is really a nice evidence will surely encourage studies in other tropical areas whereas fish-mediated seed dispersal are under suspect. This first step would be interesting to understand the ecological processes of forest regeneration (e.g. conservation programs!) along streams and rives, and also flooded areas. Besides, add new actors in the plant-animal evolutionary scenarios. The fishes, and also lizards, are considered by many authors as the 'first' seed dispersers vertebrates interacting with gimnosperms and early angiosperms. Focussing studies in these group of frugivores vertebrates around the world could help to have a nice picture of these processes under a ecological and evolutionary perspective.
This work raises many interesting spatial ecology questions. How would seed shadow and adult distribution differ between flooded areas and non-flooded areas? As far as management goes, I wonder if the authors could suggest a treshold size above which most individuals carry seeds.
How incredibly interesting that fish could play such an integral role in critical plant life. There is a need for more research in other areas of the world with similar environments. We may find through these studies that conservation in some finite areas could go a long way to preservation. I commend Galetti and his team's efforts.
'Weird' seed dispersal interactions tend to have only limited importance in a small, specific system --e.g. slugs and wetas, and seeds of the few plant species they disperse. Not so this one! It has been known for a while that fish can disperse seeds, but this study is the first to show just how pervasive and important these interactions can be in neotropical forests. Highly commended!
I went to Pantanal last summer and the place is amazing. We did fish the pacu using fruits as baits, but never realized how important they were for the forest. Nice work!
I think this is a very important study which gives a new point of view on the the capture of Big fishes and it's impact on forest conservation. I hope this paper stimulates more studies about fish seed dispersal systems to provide Brazilian government yet more concrete proofs to improve conservation laws.
Fruit feeding fish from the Amazon and the Pantanal have been studied since the seventeenth by scientists from the INPA, Manaus and from the Max-Planck Working Group for Tropical Ecology. There are numerous publications on this topic. Additionally I would like to remember the publiaction of Michael Goulding, just citing his book on "The Fishes and the Forest", published in 1980! As well have a look at Biotropica 26 (1994)on "Seed dispersal in flood plain forests of Amazonia" Ulrich Saint-Paul
I have worked with the conservation genetics of Neotropical freshwater fish for a number of years, analyzing the genetic structure of populations. Brazil has more than 2000 freshwater fish species, but approximately 140 are already considered endangered and some hydrographic basins present high endemism. Some of these endangered species feed on fruit and can be potential dispersers. Unfortunately, little attention is dedicated to these resources, although they are an important source of protein for selfish humanity. This research demonstrates the importance of a fish species as seed disperser and makes us consider that the loss of these species could result in serious consequences to the populations of plants that are dispersed by fish.
This is a fascinating study which demonstrates again the fundamental importance of seed dispersal in ecosystems, both aquatic and terrestrial. The web of complex interactions which runs through the hierarchy of plants and animals in Amazonia ought to be seriously reconsidered by decision-makers, before good-intentioned but ineffective fishery management "solutions" are implemented.
Along the Rio Negro in the Pantanal, it seems very plausible that large pacus are important for dispersal of tucum seeds longitudinally (upstream-downstream) along the main river channel and to seasonally linked, relatively-large oxbow and levee lakes. However, in comparison to the flooded forests described by Goulding for the Amazon, the flooded forests of the Pantanal's Rio Negro are much less extensive, shallower, and probably less accessible to larger fish. The gallery forest pools along the Rio Negro typically contain small curimatids, rivulids, and smaller pacu species. How far large pacus are able to penetrate this type of flooded forest and disperse seeds remains a question and could be an interesting followup study. Smaller species (or smaller pacus) may be more important for lateral (river to flooded forest) dispersal. This does not diminish the importance of the study's conclusions showing that large pacus disperse more tucum seeds. We need more data about the actual movements of different sized pacus.
I am an environmental ethicist for whom the significance of this wonderful research connects to issues of environmental value. I would suggest that a system for valuing nature must (among other requirements) be scientifically credible. Currently, we uncritically accept an economic approach to valuing nature whereby we "chunk" it up into pieces, price the chunks as if they were legal tender in a market transaction for their use as a resource or service, then count the chunks. Multiplying the number of chunks by the chunk unit price, we arrive at the total value. The assiduous work described here adds to a growing body of work that shows how utterly untenable it is to thus view a natural system. The researchers help to show us that natural systems are things that have not the faintest resemblance to a collection of discrete pieces that can be considered (and priced for the market) in isolation. An economist would ask: What is the value (price) of the Pantanal's plants? What is the (perhaps different value or price) of the Rio Negre? What is the (yet different) price that river's fish? What is the incremental value of any one of these components of the Pantanal? Reflecting on this research team's results, one sees that the framework for these questions is profoundly ignorant of our best science.
I find this study very interesting and important for two reasons. The first is the unexpected link between the aquatic and terrestrial ecosystems, which mix temporally in this valuable ecosystem. Connections like this one are probably much more common than we would previously have thought and deserve further attention. Second is the elucidation of ineffective management of Pacu populations in the Pantanal. The true impacts of conservation strategies are often not understood when they are originally put into affect. This paper illustrates well the importance of designing management with enough flexibility to adapt to future research discoveries.
The authors report a fascinating interaction envolving fish and seeds, a neglected topic in frugivory research. The importance of such interaction to the conservation of the Brazilian Pantanal suggests that more studies evaluating the role of fishes as mutualistic animals should be done in other flooded environments.
This is an important research concerning the conservation of tropical forests as it shows unique information linking aquatic and terrestrial ecosystems in the Amazon, with important consequences for how we should think about forest and water conservation in the tropics.
This study makes me remeber of my own observation in the year 1994-95 when I happened to see a few seeds ,which I presumed to be of some wild plant species,in the gut of an indigenous fish- Himalayan Mahseer(Tor putitora). I didn't carry on further with it and could not conclude that Mahseer plays an important role in seed dispersal being a carnivore.But I appreciate the work of Galetti and Donati who have been sucessfull in establishing the crucial relationship between terrestrial and aquatic ecosystem. It has opened new area for research. J.P.Bhatt