Features
Japanese Digital Television Project: An informed choice?
by Shanthilal Nanayakkara
Retired Principal Engineer, Digital Transition Division, Australian Communications and Media Authority
A Japanese delegation recently announced the resumption of the previously stalled digital television project in Sri Lanka following a meeting with the newly-elected President Anura Kumara Dissanayake. The commencement of the digitisation project is now imminent.
Once terrestrial television transmissions are digitised in Sri Lanka, it will replace the old analogue terrestrial television forever. Therefore, it is critically important that the final outcome is better than the current analogue television, if not far superior. Setting such a goal prior to the implementation of the project is crucial for its fruitful completion.
To achieve this outcome, deficiencies in the current parameters in the Japanese Digital Plans need to be revisited and appropriately addressed for the benefit of all stakeholders. Otherwise, as it stands today, there is a high potential for rural and regional viewers in Sri Lanka to miss out on the digital coverage. (This is further illustrated below). Such an unwarranted outcome could become a highly ‘politically sensitive’ issue for the new government .
Why Digital
In analogue transmissions, radio waves encounter several problems. When radio waves are subjected to multipath, ghosting images appear on television screen. They are also subjected to cancellation of their own signals and interference.
Digital technology overcomes these analogue transmission weaknesses and, as a huge value addition, is able to carry more information than its analogue counterpart. As this capacity enhancement feature helps carry multiple programmes on one frequency or channel, digital television transmission technology is considered to be highly spectrum productive. Once analogue is switched off, the vacant spectrum that can be harnessed, commonly known as Digital Dividend (DD), becomes an income earner for the Government, as spare spectrum can be sold to Telcos for broadband internet use. Thus, this digitisation project is effectively a self-financing venture for the government and a win-win for all stakeholders.
Stakeholder benefits of digital
Many countries in the world have now moved or are in the process of moving to the digital domain.
Irrespective of the digital television transmission standard adopted in Sri Lanka, benefits of a conversion from analogue to digital television are many for the majority of stakeholders.
These are listed below against the various stakeholders:
* Government – a significant income from selling the vacant spare spectrum to Telcos, following full conversion to digital, provided appropriate modifications are made to the JICA plan;
* Broadcasters – increased television channels and scope for increase of advertising revenue;
* Viewers – increased number of television channels to facilitate a wider selection of content, with True High Definition (True HD) quality and potential 5.1 Surround Sound;
* Content providers – opportunity to produce a wide range of programmes that are in demand;
* Production houses – larger revenue from vastly increased niche productions;
* Creators of social media and other internet-based content – opportunities to develop novel visual and aural media content;
* Electronic Manufacturing/Testing – opportunities to manufacture digital television receivers and set up a receiver harmonisation/compatibility centre;
* Broadcast Towers (similar to Lotus Tower) – Opportunities to establish and operate consolidated broadcast towers in the country;
* Telcos- opportunity to purchase superior vacant spectrum for future fixed and mobile broadband applications.
Funding arrangements or self-financing
The current funding arrangement for digitisation of television in Sri Lanka is a ‘soft loan’ from the Japanese government, and it is tied up in ‘one bundle’ with loans for other projects. This loan is also based on the premise that the deployment of the Japanese digital television standard, Integrated Services Digital Broadcasting-Terrestrial (ISDB-T) is mandatory. As the vacant spectrum can be sold after Analogue Switch Off (ASO), the venture could also be a self-financing project, albeit with bridging finance.
Purpose of this essay
The main purpose of this article is to suggest ways of optimising the benefits of the digitisation project while retaining the support of the Japanese government. If the bulk of problems for viewers and broadcasters can be removed by making appropriate adjustments to the current plans at a minimal cost, with broadcasters becoming willing participants, the digitisation of television in Sri Lanka would no doubt be a success for all stakeholders, including the new government. Otherwise, there is an urgent need to review the bi-lateral agreement that was signed previously.
The broadcasting fraternity in Sri Lanka is fully aware that the Japanese system is not as efficient as the second generation European standard, Digital Video Broadcast-Terrestrial 2 (DVB-T2).
Understanding Digital
Simply put, digitisation of analogue vision and sound enables radio waves to carry more information within the same channel or bandwidth than in the analogue era. This allows producers of visual and aural content to be more creative than before. The technology also facilitates easy communication in both fixed and mobile environments and facilitates two-way communication more than in the analogue era. However, there are two main pitfalls that one needs to address in order to make the venture a success. They are as follows:
Cliff effect (sudden loss of signal): –
* to avoid the ‘cliff effect’ a robust signal (with higher reliability and availability at a receive location than in analogue era) is needed at the receiver to prevent momentary picture pixelation and/or sudden loss of signal; and
* it is also necessary to ensure that all television digital services reaching viewer locations are of the same signal strength to ensure equity of services and therefore must originate from ONE location such as the Lotus Tower.
* Absence of ‘graceful degradation’ and its effect on signal level – even with a degraded signal with ‘snowy pictures’, analogue signal is still watchable. It is not so with digital due to ‘cliff effect’. Therefore, there is a need to ensure that the digital coverage is the same or better than the existing watchable analogue coverage that is defined by a signal level of 43 dBuV/m in VHF Band III.
This limit was adopted for digitisation in Australia.
Deficiencies of the Japanese standard/plan
In planning to deploy the ISDB-T system in our country, everyone should aim for a cost-beneficial outcome as it is of paramount importance to all stakeholders. There are several issues in the Japanese documentation of 2014/2018, which should be addressed to suit the needs of the public/consumers, broadcasters and government. They range from policy issues at the outset, technical areas during planning and management issues during the proposed phases of ASO and Digital Switch On (DSO).
Spectrum for Digital: VHF/UHF issue
In particular, the proposal to use only a part of the available broadcast spectrum has an impact on the eventual DD income for the Government. The Japanese have deployed both VHF and UHF spectrum in Brazil, strangely not offered to Sri Lanka. In that context, it is not clear why the Japanese team has not proposed a VHF and UHF combined solution as deployed in Brazil. This was pointed out by the writer when a Japanese team, including a senior Embassy official Sato Takefumi, met him in 2017 in Colombo to discuss Lotus Tower issues (after his disclosure in an article in The Island about the Lotus tower) and digitisation in general. Their response was ‘no one asked for it’.
As it stands today in Sri Lanka, analogue television transmissions are based on frequencies using both VHF and UHF Bands, but the proposed Japanese digital conversion is not utilising the VHF Band. In particular, VHF Band III exhibits superior propagation characteristics, while contributing to lower the consumption of electricity by the transmitters. More importantly, VHF radio waves carry longer distances than UHF due to lower propagation losses, are able to travel around obstacles comparatively and therefore VHF is more suitable for wide coverage transmissions.
Currently, the VHF spectrum is occupied by three television broadcasting networks i.e. Rupavahini, ITN and TNL. These networks will lose their inherent wide coverage VHF Band advantage. They also have the additional burden of occupying a digital channel in the UHF spectrum, especially when the earmarked UHF channels for digital are almost at the bottom of the UHF Band V, where propagation losses are higher than in UHF Band IV.
ISDB-T New Coder H.265
It is a known fact that the Japanese ISDB-T standard, in payload capacity terms, is second to the second generation European Standard DVB-T2 that provides 45 Mb/s capacity. However, the Japanese standard can only carry about 1/2 of the European standard per channel at 23 Mb/s. But as the Japanese are now offering to change the content source coder to H.265, they will be able to provide HD at 1080P at a rate of 2-4 Mb/s. This change would now allow all HD TV ready broadcasters to provide True HD content at 1920 x 1080P and possibly can accommodate all television channels in Colombo. But the downside is that the receivers are going to be more complex with the new coder. This may then lead to more expensive ISDB-T receivers or STBs in Sri Lanka.
Vacant VHF Band III
The unused VHF Band III is likely to reduce the DD for the government though the Japanese strategy is to achieve some productivity by the use of single frequency networks in the UHF Band (SFNs-a technique to use the same frequency multiple times to improve spectrum productivity). However, in practice receiving of SFNs is not simplistic as the reception of SFN signals are subject to receiver complexities.
The Telecommunications Regulatory Commission (TRC) may be exclusively reserving the VHF band for future digital radio, but the same band could be co-shared with digital television without any problems. For example, Australia is co-sharing VHF Band III for both digital television and radio without any issues.
Once all analogue transmissions are switched off with the deployment of UHF band per se for digital, the unused VHF Band III spectrum, where 7 MHz bandwidth, 8 VHF Frequency channels exists, will become vacant.
This is clearly a waste of unused spectrum. Additionally, as Restacking [restack is the re-arrangement of frequencies ideally in the two bands of VHF and UHF, to maximise the spectrum productivity] is in the Japanese Plan, additional expenditure on broadcasting infrastructure is also on the cards. Where are the funds coming from?
There is no mention of new funding arrangements for Restacking of the spectrum, and it also raises questions about the STB/Receiver specifications as frequencies may need to change after Restacking.
If some broadcasters are not keen to use ISDB-T, they may canvass for the opportunity to use the vacant VHF Band for the potential deployment of DVB-T2 standard. This MUST be avoided at all costs! If this happens, there will be two digital systems in Sri Lanka. This issue, in particular, could become another potential headache for the government as it is likely to be under heavy pressure from commercial broadcasters to release the vacant VHF Band III for the more efficient DVB-T2. This issue, too, was pointed out by the writer when another Japanese team consisting of a Senior Engineer from Yacheo Engineering along with Sato Takefumi of the Japanese Embassy met him in 2017/2018.
Unless there are plans to use the vacant VHF Band III by Restacking the spectrum, this spectrum specifically allocated for broadcasting would go to waste.
Digital Signal Reliability & Availability
Unlike in the analogue domain, television signal reliability and its availability becomes crucial in digital reception. In the analogue era, television broadcasting service field strength was planned for 50% of the locations and 50% of the time at a receiving height of 10 m. But in digital this becomes 80%-95% of the locations and 90% of the time to ensure reliability and availability of the digital signal. Hence the planned field strength would need to be adjusted to ensure the required reliability and availability at a higher field strength. In Australia, field strength used was 50 dBuV/m for Band IV and 54 dBuV/m for Band V frequencies in a rural environment
However, it is not clear from the published documents of the Japanese plans 2014/2018 whether this issue had been addressed or otherwise. The signal level at 51 dBuV/m identified in the 2018 Japanese documentation is certainly not adequate for a rural grade of service in the UHF Band! It ought to be in the region of 54-74 dBuV/m in the UHF Band V. For example, the Australian Broadcasting Planning Handbook for Digital Television Broadcasting has clearly identified these requirements and provided information on how they were derived.
Duplication Parameter
The potential impact of the proposals for duplication of coverage is illustrated in the diagram. (See Figure 01)

The signal threshold of a planned analogue coverage is 50 dBuV/m for VHF Band III. However, some regional and rural viewers in Sri Lanka are currently receiving watchable analogue signals well below this value. If, as planned by the Japanese studies in 2014, the analogue coverage is converted at the planned cut-off level of 55 dBuV/m, then the majority of regional and rural viewers, who are currently watching the analogue television with no issues, will not be able to receive digital television coverage. This could potentially become a political nightmare for the new government. Therefore, the cut-off signal level, as illustrated above, should be lowered to 43 dBuV/m.
Though Single Frequency Networks (SFNs) are a solution to mitigate this difference in coverage, it is not easy to implement them at the receiver-end due to the variation in receiver profiles of Set-Top-Boxes (STBs) and complexities in receiver SFN signal detection.
The Japanese designers, while being aware of this issue, may have been heavily constrained due to the requirement for spectrum productivity. Most probably, given the limits of the available UHF spectrum for digital and the lower data efficacy of the Japanese ISDB-T standard, this higher limit of duplication may have been proposed by the designers in order to preserve some spectrum productivity.
One Network Operator for Digital
The advent of digital terrestrial television also signifies the end of individual transmission facilities for broadcasters, as several content feeds are carried on one frequency or the channel and the requirement to consolidate all transmissions at one site. A combined digital transmission service provider may, in the future, be an independent entity and the facilities may be offered to the broadcasters on a fee-levying basis, based on a pragmatic business plan. In a future digital broadcasting landscape, the broadcasters will essentially be ‘content’ providers. Perhaps, there ought to be some sort of protection provided to the existing broadcasters in the event new content providers also express a desire to use digital transmissions.
Cost to viewers and broadcasters
All consumer television sets require digital receivers to extract video and audio content from digital transmissions. Therefore, either in-built ISDB-T receivers or compatible STBs are required. For example, there are flat TVs that do not have in-built ISDB-T receivers. The cost of an STB for ISDB-T with H.265 decoders, is likely to be around US $ 50-100, depending on their complexity and economies of scale. If in the event, there is likely to be a Restack of frequencies including the VHF Band, two band STBs or receivers may be needed; one during the first phase and another after the Restack of channels with the ability to tune into the VHF Band. Additionally, at some household locations, there may also be a requirement for new receiver antenna installation to receive VHF/UHF channels. If so, this is also an additional cost to the viewer.
There is also a significant cost to the commercial television broadcasters to provide HD ready studios, Outside Broadcast (OB)/Electronic News Gathering (ENG) equipment, and content feeding arrangements. However, once the commercial television broadcasters elect to use consolidated broadcast towers, analogue era transmission costs would also disappear as their independent transmission networks are no longer needed, in a digital environment. It is noteworthy to highlight that the Japanese financial proposal for digitisation of television is primarily for Rupavahini, and limited to funding the analogue to digital transfer of Rupavahini facilities, including the provision of a True HD studio, OB unit, Transmission equipment and a Central Command centre for the proposed Digital Broadcast Network Operations (DBNO) at the Lotus Tower.
At this stage, there are no signs of any discussions with the broadcasters to develop a ‘road map’ to facilitate the smooth transition from analogue to digital of commercial channels. If Restack is to take place, there is likely to be additional costs but there is no mention of further Japanese funding for Restack of channels either.
As additional costs to the commercial television broadcasters are likely, strategic government policy initiatives to compensate for the additional capital expenditure in a highly competitive market are in order.
Way forward
It is heartening to note that the Japanese plan has now incorporated the more efficient coder in H.265 with an intention to maximise the use of limited payload capacity of an ISDB-T channel, which then will result in providing True HD transmission (1920 x 1080P) for ALL licensed television channels in Colombo.
If Japanese consultants can pay attention to the issues of using VHF Band III, changing receiving the field strength requirements to that of the ITU signal level requirements for UHF and address the duplication parameter issue, then ALL stakeholders including the government and broadcasters will no doubt look forward to the venture of digitisation of television in Sri Lanka.
Features
US-Iran war, global exchange rates and Sri Lankan Rupee
When the strait shuts:
In the early hours of February 28, 2026, the world changed. Joint United States and Israeli airstrikes on Iran, meticulously planned, devastatingly executed, killed Supreme Leader Ali Khamenei, destroyed large swathes of Iran’s nuclear infrastructure, and triggered the most consequential military confrontation in the Middle East since the Iraq War. What followed was not merely a regional conflict. It was an economic earthquake felt from the trading floors of New York to the fuel queues of Colombo.
We are going to examine how a war fought in the Persian Gulf rewrote exchange rates across the global economy, and why a small island in the Indian Ocean, still recovering from its own financial near-death experience four years ago, found itself once again staring into an economic abyss.
From Maximum Pressure to Maximum Destruction
On February 28, the strikes began. The operation was vast and transformative. Iran’s air defences were systematically destroyed. Its missile production facilities were crippled. And its political leadership was decapitated. In response, Tehran did something it had always threatened but never done: it closed the Strait of Hormuz.
That decision, to block the 21-mile-wide waterway through which approximately 20% of global oil supplies flow, set off a chain of economic consequences that no government, central bank, or multilateral institution had fully stress-tested for.
The Oil Shock and What It Did to Currency Markets
The numbers tell the story with stark clarity. Brent crude, which had been trading at $71.32 per barrel on February 27, jumped 8% to $77.24 in the first two trading days of the conflict. Within a week, following the declaration that the Strait was “closed,” WTI crude surged more than 35%, the biggest weekly gain since the futures contract began in 1983, ending the week at $90.90. Brent climbed 28% to $92.69 in the same period. By early March, Brent had surged past $120 per barrel. The International Energy Agency characterised it as the “largest supply disruption in the history of the global oil market.”
This was not merely an oil price story. Oil is the world’s most foundational commodity, priced in US dollars, embedded in the cost of virtually every manufactured good, agricultural product, and service. When oil prices surge by 45%, as they did between February and April 2026, the consequences ripple through exchange rates with a logic that is both mechanical and unforgiving.
For oil-importing emerging market currencies, the mathematics were brutal. When oil prices rise in dollars and a country pays for oil in dollars, there are two simultaneous pressures on the exchange rate. First, the country must acquire more dollars to pay for the same volume of imports, increasing demand for the greenback and putting downward pressure on the domestic currency. Second, higher oil prices widen the current account deficit, removing the trade-balance support that usually anchors currencies. This double blow struck Asian, African, and Latin American currencies with particular force. Gasoline prices rose in 106 countries in the three weeks following the start of the conflict. The European Central Bank postponed planned interest rate cuts, raised its inflation forecast, and cut its growth projections.
Oil exporters told a different story. The Gulf states, Saudi Arabia, the UAE, Kuwait, saw windfall revenues at the very moment their physical infrastructure was under threat. Iran’s strikes on Saudi Arabian oil refineries and energy facilities injected volatility into the already fractured GCC calculus: higher oil revenues on one hand, higher security costs and diplomatic complexity on the other.
The Ceasefire and Its Limits
After five weeks of fighting, Pakistan and China delivered a joint peace initiative on March 31, 2026. On April 7–8, the United States and Iran agreed to a two-week ceasefire, with Iran committing to reopen the Strait of Hormuz. Markets reacted with violent relief. The S&P 500 and Nasdaq surged 3–4% in futures markets overnight. Oil prices fell nearly 25% from their peak. Equities that had slid 8–12% from pre-conflict highs began recovering.
But the ceasefire was “relief, not resolution.” The Strait of Hormuz remained at just 5% of pre-conflict shipping traffic five weeks after the ceasefire announcement. Supply chains do not unsnarl overnight. On May 7, the United States conducted further airstrikes on military sites in southern Iran and Tehran following Iranian targeting of US warships. A memorandum of understanding, intended to bring the conflict to a formal end within 60 days, was announced by mediators on June 14, with signing set for June 19. As of this writing, the conflict has not been formally resolved and nuclear negotiations are expected to begin under the framework.
Goldman Sachs projected that under an adverse scenario, 10 weeks of disruption and infrastructure damage, Brent could peak at $160 per barrel before settling at $115 in the fourth quarter of 2026. Even the base case of $105–115 per barrel through mid-year represents a sustained energy shock with no parallel in the post-2008 global economy.
Sri Lanka: The Compound Vulnerability
Sri Lanka has a particular relationship with oil price shocks that is unlike almost any other country of its size. It imports 100% of its oil. Its domestic energy infrastructure is built almost entirely around petroleum products. Its foreign exchange reserves, rebuilt painstakingly from near-zero during the 2022 crisis to $6.46 billion by the time the NPP government assumed office, have since grown sluggishly reaching only $6.87 billion by early 2026, a modest gain that offered little buffer against a shock of this magnitude, remain thin relative to the country’s import requirements. And it routes the overwhelming majority of its oil imports through the Strait of Hormuz.
When that strait closed in March, 2026, Sri Lanka’s exposure was immediate, structural, and arithmetically severe. The fuel import bill jumped 74.7% year-on-year to US$630 million in March, 2026, alone. Reserves fell 3.8% to approximately $6.7 billion after the country spent $1.5 billion on fuel imports in the first four months of the year. Sri Lanka’s monthly storage capacity covers only one month of consumption, making it acutely vulnerable to supply disruptions that persist beyond a few weeks.
The exchange rate impact was direct and rapid. The Sri Lankan rupee, which had traded at approximately Rs. 300 to the US dollar at the start of 2026, fell sharply from early March. The currency tumbled 8.7% from its pre-conflict level within weeks. By late May 2026, commercial bank selling rates stood at approximately Rs. 334 per dollar, a 5.4% year-to-date depreciation against the greenback.
Every rupee of depreciation compounds the damage: a dollar-priced barrel of oil that cost Rs. 21,300 at Rs. 300/$ costs Rs. 23,700 at Rs. 334/$, before accounting for the price rise in the barrel itself.
The compounding of the exchange rate depreciation on top of the oil price surge created a fuel price crisis that has no precedent in the post-2022 recovery period. Petrol 92 at CEYPETCO stations, which stood at Rs. 293 per litre 12 weeks before, had risen to Rs. 434 per litre by late May, a 48% increase in the space of three months. The true import and distribution cost of diesel was approximately Rs. 750 per litre, requiring a government subsidy of Rs. 57 billion over a three-month period to keep pump prices at Rs. 407.
The Central Bank’s Painful Choice
The Central Bank of Sri Lanka faced the classic emerging market dilemma that oil shocks create: a currency under pressure from capital outflows and import costs, combined with inflation driven by energy prices, in a context where raising interest rates to defend the currency would choke off the economic recovery that the country had barely begun.
On May 26, 2026, the CBSL made its call. It raised the overnight policy rate by 100 basis points to 8.75%, its first monetary tightening in three years, and the largest single hike since the depths of the financial crisis in March 2023. Seven out of twelve economists polled by Reuters had predicted only a 25-basis-point move. The shock was deliberate: the CBSL was signalling that price stability had been elevated over growth promotion.
The consequences were immediate. The Colombo Stock Exchange fell 0.8% on the day of the announcement. Growth forecasts were cut, from 4.2% to 3.0% by at least one major equity research firm. The Central Bank Governor acknowledged that the 4–5% growth projection for 2026 was now achievable only “at the lower band.” Capital Economics observed that the rate hike “highlights the country’s vulnerability to the crisis in the Middle East, and is unlikely to be the last unless the crisis subsides soon.
More encouragingly, BMI (a Fitch Solutions unit) projected that the rupee could recover to Rs. 320 per dollar by year-end, on the assumption that the Iran war concludes by June and oil prices ease. An IMF board meeting was scheduled to approve a $700 million tranche to Sri Lanka under the ongoing $2.9 billion programme, a lifeline that, if disbursed, would provide critical reserve support.
The Broader Lesson
What the 2026 Iran war has demonstrated, with a clarity that no academic model can replicate, is that geopolitical shocks are not symmetric in their exchange rate effects. The same event that provides a windfall for oil exporters imposes a compound penalty on oil importers, and the penalty is largest for countries whose currencies are weakest, whose reserves are thinnest, whose import dependence is highest, and whose recovery from previous crises is most recent.
Sri Lanka is, in 2026, the canonical case study. It has done almost everything right since 2022: restructured its debt, rebuilt reserves, maintained an IMF programme, restored exchange rate stability, and begun recovering economically. None of that inoculated it against an exogenous shock of this magnitude. The rupee’s 8.7% fall from pre-conflict levels, the $1.5 billion fuel import bill in four months, the 100-basis-point emergency rate hike, these are the costs a small, import-dependent, oil-importing island economy pays when the world’s energy arteries are severed by war.
There is a policy lesson embedded in these numbers. Sri Lanka’s energy vulnerability, its total dependence on imported fossil fuels routed through a single geopolitical chokepoint, is not merely an economic problem. It is a national security problem. The Strait of Hormuz is not a permanent fixture of reliable global trade. The 2026 war has proven, at enormous cost, that it can be closed. Any serious national energy strategy must treat that closure not as a tail risk but as a planning scenario.
The hard work of diversifying energy sources, accelerating renewable capacity, building strategic petroleum reserves, and reducing the share of petroleum in the import bill is not merely desirable. Since February 28, 2026, it has become existential.
(The writer, a senior Chartered Accountant and professional banker, is Professor at SLIIT, Malabe.
Views expressed in this article are personal.)
Features
Forest cover loss threatens rare freshwater fish in Sinharaja streams
When discussions turn to Sri Lanka’s freshwater fish diversity and the urgent need to conserve it, attention is often focused on rivers, streams, reservoirs and water quality.
Yet scientists are increasingly finding that what happens on the land surrounding these waterways can be just as important as what happens in the water itself.
A recent study led by researcher Janamina Bandara of the Wildlife Conservation Society, Galle, together with researchers Sudath Nanayakkara and Sahan Randeniya, highlights how changes in forest cover caused by human activities can significantly influence freshwater fish populations in the hill streams surrounding the Sinharaja rainforest.
Their research sheds light on a relatively understudied aspect of tropical freshwater ecosystems—how alterations to vegetation cover, particularly through commercial cultivation such as tea and cardamom plantations, affect fish communities inhabiting headwater streams.
Hidden Riches of Tropical Streams

Forest plant saplings
Sri Lanka’s freshwater ecosystems are globally recognised for their remarkable biodiversity and high levels of endemism. However, despite their ecological significance, many ecological processes operating within these habitats remain poorly understood.
“Freshwater ecosystems in the tropics harbour extraordinary biodiversity, but many of the ecological relationships within these systems are still not fully documented,” researcher Janamina Bandara told The Island.
The study focused on sub-montane streams in the Sinharaja landscape, examining how varying levels of forest cover influence freshwater fish assemblages.
Researchers investigated whether fish communities differed between streams flowing through relatively undisturbed forests and those surrounded by modified vegetation resulting from agricultural activities.
Spotlight on a Critically Endangered Species

Leaf litter bay / Restoration activities
Particular attention was given to the critically endangered Rakwana loach (Schistura madhavai), a highly restricted endemic fish species first described from the Suriyakanda-Rakwana region.
Commonly referred to as a hill-stream loach, the species inhabits clear, fast-flowing streams and is considered highly sensitive to environmental disturbances.
According to Bandara, while broad community-level analyses did not reveal dramatic differences across all fish populations, species-specific responses painted a very different picture.
“Our findings show that Schistura madhavai exhibits a clear preference for streams flowing through intact forest habitats,” he explained. “The species becomes less common in areas where surrounding vegetation has been altered by human activities.”
Why Forests Matter to Fish
Forests bordering streams play multiple ecological roles. They regulate water temperature by providing shade, contribute organic matter that supports aquatic food webs, stabilise stream banks and help maintain water quality.
When these forests are removed or replaced with plantation crops, the resulting environmental changes can cascade through freshwater ecosystems.
Bandara noted that altered forest cover can influence water chemistry, microclimatic conditions, stream-bed composition and the availability of food resources.
“As riparian vegetation changes, a series of environmental conditions within the stream also change. Sensitive species such as Schistura madhavai appear particularly vulnerable to these shifts and may gradually disappear from modified habitats,” he said.
The research suggests that even subtle changes in habitat structure can have disproportionate impacts on species with narrow ecological requirements.
The Importance of Looking Beyond Numbers

Schistura madhavai
One of the most intriguing findings of the study is that ecosystem degradation may not always be apparent when scientists assess entire fish communities collectively.
In some instances, environmental variables appeared to have little effect on overall fish abundance or diversity. However, when individual species were examined separately, clear patterns emerged.
For example, variations in the amount of detritus—organic matter that accumulates on stream beds and serves as a vital food resource—did not significantly affect the overall fish assemblage. Yet for certain species, including habitat specialists, such changes proved critically important.
“This highlights a key conservation challenge,” Bandara said. “If we only look at total fish numbers or community-wide patterns, we may overlook serious declines occurring among environmentally sensitive species.”
Indicator Species as Ecological Sentinels
The findings underscore the importance of using so-called “indicator species” in environmental monitoring programmes.
Indicator species are organisms whose presence, absence or abundance reflects the health of an ecosystem. Because they respond rapidly to environmental change, they can provide early warnings of ecological degradation.
The Rakwana loach appears to fit this role exceptionally well.
“Species with narrow habitat requirements often act as ecological sentinels,” Bandara observed. “Monitoring them can provide a much clearer picture of ecosystem health than relying solely on broad biodiversity assessments.”
For conservation practitioners, this means that protecting sensitive endemic species may also help safeguard entire freshwater ecosystems.
Restoring Streamside Forests
Perhaps the study’s most important conservation message concerns the restoration of degraded riparian forests—the vegetation growing alongside streams and rivers.
Researchers argue that restoring these streamside habitats should be a priority in freshwater biodiversity conservation efforts.
Healthy riparian vegetation provides shade, reduces erosion, filters pollutants, enhances habitat complexity and supports the intricate ecological interactions upon which aquatic life depends.
“The restoration of degraded riparian forests is likely to be one of the most effective conservation measures for protecting freshwater biodiversity,” Bandara emphasised.
Such efforts could prove particularly valuable in landscapes where agricultural expansion has fragmented natural habitats.

Awareness sessions
A Broader Lesson for Conservation
The study offers a timely reminder that freshwater conservation cannot be achieved by focusing exclusively on water bodies themselves. The surrounding landscape matters immensely.
From the mist-laden streams flowing down the Sinharaja foothills to the countless rivulets nourishing Sri Lanka’s river systems, the fate of freshwater biodiversity is intimately linked to the health of adjacent forests.
As conservationists grapple with accelerating habitat loss and climate-related pressures, the research demonstrates that protecting and restoring forest cover may be just as important as safeguarding the streams themselves.
In the case of the elusive Rakwana loach, the message is clear: save the forest, and you may save the fish.
For Sri Lanka’s unique freshwater biodiversity, that lesson could not be more important.
By Ifham Nizam
Features
Turning Promises into Justice
Sri Lankans have reason to take satisfaction in their country’s latest international achievement. Sri Lanka has climbed 14 places in the 2026 Global Peace Index to rank 67 in the world out of 163 countries that were assessed. At a time when global peacefulness is reported to be at its lowest level since the inception of the Index, and when more countries are experiencing deterioration than improvement, Sri Lanka’s progress stands out. The ranking reflects the country’s recovery from nearly three decades of war, its efforts to strengthen political stability and public security, and its resilience in overcoming the economic and political crises of recent years. The Global Peace Index assesses the strength of institutions, societal safety and security, and the capacity of societies to manage conflict peacefully.
The challenge is to consolidate the gains that have been made and address those unresolved issues that continue to cast a shadow over the country’s future. It is in this context that two recent announcements by the government assume particular significance. Foreign Minister Vijitha Herath has announced that the Prevention of Terrorism Act (PTA), one of the most controversial laws in the country, will be repealed and replaced within two months. A report prepared by a committee appointed to make recommendations has already been handed over to him. According to the minister, the new legislation, to be known as the State Prevention of Terrorism Act, incorporates recommendations from civil society and is intended to comply with international standards on counter terrorism.
At the same time, Justice and National Integration Minister Harshana Nanayakkara has reaffirmed the government’s commitment to uncovering the truth about missing persons. During a visit to the Chemmani mass grave excavation site in Jaffna, he stated that the excavations should be completed expeditiously so that justice can be done and assured that the necessary resources have been allocated for the task. The excavations are taking place under judicial supervision with the participation of forensic experts, archaeologists, lawyers and representatives of the Office on Missing Persons. These commitments made by the government address two of the most contentious issues that have troubled Sri Lanka for decades. They also suggest that the government believes the country is now in a position to deal with difficult questions from its past rather than postpone them indefinitely.
After Breakthroughs
The timing of the pledge to repeal the PTA is particularly noteworthy. For many years successive governments promised to replace the law but failed to do so. Sri Lanka undertook to repeal it in 2017 as part of its commitments linked to retaining GSP Plus trade concessions by the European Union. Yet despite repeated assurances the law remained in force. The question therefore arises as to why the government now appears determined to act. One possible explanation is that the Easter Sunday investigations have reached a decisive stage. The investigation into the bombings that killed more than 260 people in 2019 appears to have made significant breakthroughs. If these investigations continue along their present course, it is possible that accountability will extend beyond those who directly carried out the attacks to those who may have facilitated, enabled or been part of a wider criminal conspiracy.
There is broad agreement within society that those who masterminded the dastardly Easter bombing must be held accountable and that the victims deserve the truth and justice. However, it is important that the process by which responsibility is determined is seen by the public to be fair, lawful and impartial. If those accused are convicted following a transparent judicial process that respects due process and the rule of law, the outcome is far more likely to gain acceptance across society. This is where the repeal of the PTA becomes important. A transition from a law associated with prolonged detention and exceptional powers to one that is more consistent with human rights standards would strengthen rather than weaken the legitimacy of the investigations. Accountability obtained through a process that is visibly fair will be more durable and less vulnerable to allegations of political motivation or selective justice.
The Chemmani excavations may also provide an example of how such credibility can be built. The process is taking place under judicial supervision and in full public view with the participation of independent experts. Whatever conclusions emerge, and follow up action is decided on, the process itself should command respect because it is transparent and accountable. The same principles can be applied to the Easter Sunday investigations. Public confidence is strengthened when investigations are conducted openly, when legal safeguards are respected and when the rights of both victims and accused persons are protected. The significance of these investigations may extend beyond the tragedy itself. There is likely to be an overlap between those who are eventually found responsible for the Easter Sunday conspiracy and elements of the state apparatus that exercised power during the final stages of the war.
Setting Precedent
For many years Sri Lanka has struggled to address allegations of wartime abuses. The issue has remained politically sensitive because it touches upon the conduct of those who were regarded by many as wartime heroes. Yet if the Easter Sunday investigations establish that senior officials can be investigated and held accountable when evidence warrants it, an important precedent will have been set. Once the deck is cleared through the Easter Sunday investigations and the judicial process that follows, it may become less difficult to address allegations relating to wartime abuses, including those connected to sites such as Chemmani where evidence is now being painstakingly uncovered. This would also strengthen Sri Lanka’s position internationally.
Since the end of the war in 2009, the country has remained under varying degrees of scrutiny by the United Nations Human Rights Council. In October 2025, the Council renewed the mandate of the Office of the High Commissioner for Human Rights to continue collecting and preserving evidence relating to past violations. The next review of Sri Lanka is due in September this year. The government now has an opportunity to demonstrate that Sri Lanka is capable of addressing difficult issues through its own institutions and according to its own democratic values. The commitments to repeal the PTA and to pursue investigations into missing persons can be seen in that light. Those who were victimized query as to what happened to their loved ones and to the information they know full well they entrusted to the government authorities and to the commissions of inquiry that were appointed. These are opportunities to show that accountability and national ownership can go hand in hand.
Reconciliation requires the difficult task of remembering truthfully. Too often Sri Lanka has sought stability by postponing difficult questions. Yet unresolved grievances do not disappear. They persist across generations and continue to shape political attitudes and communal relationships. Sri Lanka’s rise in the Global Peace Index is an achievement worth celebrating. But the true measure of peace is not only the absence of conflict. It is the presence of justice, trust and confidence in public institutions. The government’s commitments on PTA repeal, the Easter Sunday investigations and the search for truth regarding the disappeared suggest an awareness that old approaches have run their course. The government has an opportunity to break with the patterns of the past. The test now lies in implementation.
by Jehan Perera
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