Peat Swamp fishes of Southeast Asia
Diversity Under Threat

The conservation of lowland rainforests is high on the conservation agenda of many tropical countries. Associated with conservation is the need to understand the tremendous diversity of plant and animal life present in the various habitats. Only when we know what is present can proper decisions be made and reasonable conservation plans established.

Betta livida, the "Jealous" Fighting fish from Malaysia peat swamps.

Freshwater fishes are important in almost all freshwater habitats. They are prime marker organisms, excellent indicators of a habitat's health (Ng, 1991a).

Of all the kinds of freshwater habitats present in Southeast Asia, one of the most neglected and least studied are peat swamps. With a spongy, water-ladened substrate formed of slowly decaying vegetation, tea-coloured waters which appear almost black when seen under reflected light (hence their name - blackwaters), with low oxygen levels, very low calcium concentrations and very high acidity (sometimes as low as pH 3), peat swamps are a very extreme habitat for any organism (Johnson, 1968; Ng et al., 1992, 1994; Low & Balamurugan, 1989). The animals living in the blackwaters of peat swamps remain very poorly studied. While the bird and mammal fauna is reasonably well known, the same cannot be said of almost every other group (see Ng, 1993a). Even for a group as supposedly well studied as fishes. In fact, until recently many biologists, following "published wisdom", felt that peat swamps had a rather low biodiversity and productivity (e.g. see Johnson, 1968).

History

Over the last 10 years, our knowledge of peat swamp fish fauna has increased by leaps and bounds. This has resulted from the interest shown by a small group of biologists, mostly taxonomists, keen to document what is present in such a seemingly inhospitable habitat. Kottelat & Whitten (1993) has estimated that there are perhaps 900-1000 species of freshwater fishes in Southeast Asia. Of these, only a small percentage, perhaps 100-200 are peat swamp fishes, of which perhaps half are obligate, stenotopic peat swamp fishes. How important a zoological component are the peat swamp fishes?

The stenotopic blackwater snakehead, Channa bankanensis.

I will cite my experiences with the Malaysian peat swamp fauna to give an idea of what to expect (Ng, 1991b). Some 300 species of freshwater fishes are known or expected from Peninsular Malaysia (Lim et al., 1993). Of these, some 40 species (about 13% of the total fauna) have been described as new to Science only in the last 15 years (see Ng, 1993d). Some 55 species of peat swamp fishes are known from Peninsular Malaysia, of which perhaps 30 are stenotopic species. Stenotopic peat swamp fishes thus represent some 18% of the total Malayan fish fauna. If we extrapolate these results for Southeast Asia for an approximation, we are dealing with a regional stenotopic peat swamp fish fauna of some 180 species. This is a very substantial diversity indeed.

North Selangor Peat Swamp Forest

One particularly well studied peat swamp deserves mention - the North Selangor Peat Swamp Forest. Of the 48 peat swamp species known from this swamp forest (Ng et al., 1992, 1994), eight species had been (or are being) described as new to Science only within the last 10 years (see Ng, 1993d for review). This means that some 17% of the fauna in the North Selangor Peat Swamp Forest was not even known to zoologists until the late 1980s (Ng, 1993c). New species include rarities and oddities like Encheloclarias and Bihunichthys, as well as brightly coloured species of Betta and Parosphromenus (see Ng & Lim, 1993; Ng & Kottelat, 1992, 1994; Kottelat & Lim, 1993, 1994; Kottelat & Ng, 1994)!

The beautiful licorice gouramy, Parosphromenus anjunganensis, from Borneo.

Another beautiful but delicate licorice
gouramy, Parosphromenus ornaticauda,
from Borneo.

A large proportion of the species found in the North Selangor Peat Swamp Forest were also new records for Peninsular Malaysia (see Ng & Lim, 1991; Ng et al., 1992). The results reflect the use of correct sampling methods (e.g. see Cramphorn et al., 1993), as well as proper taxonomic studies being conducted (see Ng, 1993d, e).

If the above results are also true for the rest of Southeast Asia, then it is very worrying statistic indeed. The North Selangor Peat Swamp Forest is a particularly well studied system (see Ng, 1991b; Ng et al., 1992, 1994). The same cannot be said of almost all other peat swamps in Southeast Asia. There are still extensive peat swamps in eastern Sumatra, Sarawak and Kalimantan which are almost unexplored. Good numbers of new species are being reported from these swamps over the last few years (e.g. Kottelat, 1982, 1991; Kottelat & Lim, 1994; Ng, 1993b; Witte & Schmidt, 1992) but these numbers are probably only scratching the surface. One could easily expect some 10-15% more species to be discovered by ichthyologists in most parts of Southeast Asia where there are still pristine swamps in years to come. Time however, is the problem.

In the last century, there were still peat swamps in western Java. These habitats are now history. We know this because of the activities of the great Dutch ichthyologist, Pieter Bleeker, who named a large number of species from all over Dutch Indonesia. Many of his species, we now know are stenotopic peat swamp species. But as Bleeker relied almost entirely on what colleagues presented him from their often random collections, from markets or fishermen, he did not get many small peat swamp species from Java. Many of the peat swamp species (or their close relatives) we are now discovering in Malaysia, Sumatra and Kalimantan must have also been present in Java, but we will never know now... Similarly, most of the peat swamps in southern Thailand have been cleared and lost, and we know very little about them. It may already be too late to do proper studies in Thailand as many of the still extant swamps are badly disturbed.

Loosing battle

Ichthyologists are fighting a loosing battle, trying to document what is in the swamps of Malaysia and Indonesia before they are irrevocably lost. This is done against a backdrop of very low funding, poor government support and shortage of competent taxonomists. Despite all the talk about conservation of biodiversity, the actual available funding, both from international as well as regional institutions is actually, very low. This is compounded by the fact that in some cases, substantial amounts of "biodiversity" aid money is improperly used or allocated to organisations or individuals with little knowledge of what they are doing.

The proper identification and naming of organisms at the species level (or alpha-taxonomy) is probably one of the most important roles of a systematist, and more so during these trying times when natural habitats are being lost at such a rapid rate. The sorting out of species problems is more important than "higher callings" like studies on their phylogeny and biogeography. At the moment, practical results are more important than theoretical formulations. Conservation, first and foremost, needs information at the species level. With desperate shortages of funds, manpower and time, we have no choice - priorities are necessary.

To add to the nightmare, many species of stenotopic peat swamp fishes are very localised distributions, being confined to specific drainages. With their restricted distributions peat swamp fishes are thus facing grave risks as swamps are being cleared at an ever increasing pace. To drive home the seriousness of this problem, consider again the fauna in the North Selangor Peat Swamp Forest. Of the 48 species present there, 13 are stenotopic blackwater species. Of these 13, about six species are known only from this or adjacent areas (Ng et al., 1992, 1994). Since most of the peat swamps along the west coast of Malaysia have already been lost or badly disturbed, the demise of the North Selangor Peat Swamp Forest will almost certainly guarantee the extermination and extinction of most of these species.

With the present statistics, it is difficult to contemplate that until the early 1980s, peat swamps were generally believed to have a depauperate fauna, with a low diversity and few stenotopic species. It was partly on this misconception that many peat swamps in Malaysia were cleared for all manner of developments. Today, some 10-20% of the original peat swamps of Peninsular Malaysia still remain. Most of the extant swamps are not completely free of human interference, and many areas have been encroached upon or disturbed to some degree or other. None of the surviving peat swamps are gazetted for protection, with the exception of a few small areas which happen to be part of wildlife sanctuaries, and the prospect does not seem good. The extensive peat swamps of the east coast of Peninsular Malaysia are being lost at a startling rate. The peat swamps of the Mawai area in Johor have almost all been cleared; and those along the coasts of Pahang and Terengganu will probably not last too long either.

Conservation

The ichthyological discoveries over the last decade underscores the nightmare facing naturalists trying to conserve Earth's biodiversity. With some 1.5 million plants and animals named by scientists, and some 3 to 10 million still unnamed, conservationists are racing against time. How does one conserve what we do not know? A good deal of conservation work today centres on trying to conserve unique habitats and areas which have a high biodiversity. It is unrealistic to expect all areas to be conserved, so compromises have to be made. Practical conservation biologists know that they have to make calculated recommendations on what must be kept, and what is expendable. The grim reality of the matter can be summed up in one of the most vulgar maxims of warfare: some must die so that others may live. How does one make the right recommendations when we do not really know what is in a habitat? The situation with peat swamps is a case in point. Far from being a depauparate ecosystem, peat swamps possess a very interesting fish fauna which is not only very diverse, but also unique, with many species having very narrow niches and restricted ranges. These species are thus extremely vulnerable to extinction. The challenge in studying peat swamp fishes is to be able to document the fauna before it becomes extinct, or worse - becomes extinct before they are known to Science!

Uses of peat swamps

The fish fauna in peat swamps is an asset not only for academics or nature lovers. The conservation of these organisms has dividends for most of us as well. Many of the most popular aquarium fishes are from peat swamps, from which they have been harvested for decades.

The lovely peat swamp barb, Puntius rhomboocellatus.

They are a valuable long-term resource. More significantly, as many Americans have learnt the hard way, swamps are not "wastelands" as they had been labelled. They are very important in soaking up excess rainwater, controlling the water level in rivers, preventing flooding during the wet season; as well as being a source of water during dry periods. They have a myriad of other uses as well. But the conservation of peat swamps is a long-term investment, and to have the conviction to keep them for posterity needs foresight. It remains to be seen whether there will be peat swamps left in Southeast Asia when all the countries reach developed country status. As things are going now, a "holocaust" scenario is anticipated for the peat swamp fishes of Southeast Asia!

List of references.

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