How micro-barriers lead to massive losses of biodiversity and ecosystems in Bangladesh
Micro-barriers like roads and fences are fragmenting habitats and threatening biodiversity in Bangladesh. Sustainable solutions can help bridge the gap between development and nature
Have you ever noticed empty snail shells lying on the roadside and wondered what caused their demise?
Snails often end up on the roads in search of food. However, the rough asphalt of the pavement, along with its heat, hinders the movement of a snail by quickly drying its mucus. The snails thus end up stranded and helpless and eventually perish.
What seems like a trivial road or fence to us can be a massive obstacle for these tiny creatures struggling to navigate their environment. Their struggle symbolises an often-overlooked crisis unfolding in our ecosystems.
At the root of this crisis lies the concept of micro-barriers. Micro-barriers are small-scale human-made structures like tiny roads, agricultural dykes, water control systems, fences, and even the walls separating your home from the neighbouring property.
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These micro-barriers might appear to be insignificant or necessary evils in the context of development. Yet their cumulative impact on the natural world can be profound. They fragment habitats, block migration paths, and prevent animals from reaching their feeding grounds, mating areas, and seasonal habitats.
Additionally, these barriers alter natural water flows, affecting the hydrology of wetlands, rivers, and other ecosystems, which impact plant life and aquatic species. These micro-barriers are not just physical obstructions; they are ecological dead ends.
In Bangladesh, the rapid expansion of urban sprawl and rural development creates a maze of barriers for the animals to navigate and endangers biodiversity. These barriers can mean the difference between life and death for creatures like butterflies, bees, grasshoppers, snails, frogs, moths, beetles, and other insects. Notably, butterflies are among the most threatened taxa, with 188 out of 305 known species listed as nationally threatened (IUCN Bangladesh, 2015).
Additionally, of 47 frog species, nine are threatened, and six are near-threatened. Often dismissed as mere pests, these small creatures play vital roles in pollination, decomposition, soil aeration, and serve as food sources for larger animals.
Micro-barriers are disrupting their life cycles, and their plummeting numbers trigger a chain reaction that reverberates throughout ecosystems.
Countries like the US, Netherlands, and Germany have employed wildlife crossings, which are artificial transition zones, to connect fragmented habitats. Studies have shown that these crossings can reduce wildlife mortality rates by 90% compared to areas without such structures, promote genetic diversity, and increase population sizes.
Cities like Dhaka have seen a dramatic drop in wildlife that depends on these tiny creatures for food. The monkeys, once a common sight, are now rarely seen. Their population declined from 50,000 to 2000 over the past decades in Madaripur. The cuckoo's once-familiar call in the spring has almost fallen silent with every passing year. Even the obnoxious crows, sparrows, and magpies have disappeared.
The IUCN estimates there were around 800,000 birds in 1994, which decreased to 163,000 in 2018, painting a dire picture of the city's rapidly homogenising ecology.
Our wetlands, which support over 260 fish species, 257 bird species, 40 reptile species, 29 mammal species, 9 amphibian species, and hundreds of thousands of migrating birds, are also under threat. The construction of small roads, dams, fishing structures, community-built irrigation canals, and watchtowers for tourists is fragmenting the wetlands, disrupting the natural flooding cycle, and creating a barrier for migrating birds and an estimated 5,000 species of plants and animals that depend on open water or marshy environments.
Similarly, docks for fishing or transportation, cables for small-scale energy projects, and tiny roads or pathways constructed for the benefit of locals and tourists all contribute to the isolation of certain species populations in the Sundarbans mangrove forest.
These barriers affect the movement of endangered Bengal tigers, spotted deer, smooth-coated otters, and wild cats. They also impact the breeding grounds of saltwater crocodiles, riverine turtles, and crabs.
Because of these micro-barriers, our diverse animal species are vanishing in silence. We must prioritise creating and preserving ecotones— transitional zones between separate habitats that allow for better movement and interaction among species.
Countries like the US, Netherlands, and Germany have employed wildlife crossings, which are artificial transition zones, to connect fragmented habitats. Studies have shown that these crossings can reduce wildlife mortality rates by 90% compared to areas without such structures, promote genetic diversity, and increase population sizes.
A striking example of an animal corridor in Bangladesh is the Dohazari-Cox's Bazar railway line, which includes South Asia's first elephant overpass at Chunati to safeguard the movement of endangered Asian elephants.
While it is a commendable initiative, all infrastructure developments must incorporate comprehensive wildlife corridors to guarantee the long-term preservation of species and biodiversity.
Strategies like using wildlife-friendly fencing, tunnels, and culverts for smaller animals like rats, hog badgers, mongooses, monitor lizards, frogs, snakes, etc. can reduce the barrier effect of infrastructure.
Canopy bridges can connect two or more large trees on either side of the road or a rail track to facilitate wildlife crossing, especially monkeys and squirrels. In 2022, Brazil's artificial canopy bridges restored forest connectivity, with over 500 crossings by eight arboreal species recorded within 11 months. Green roofs can be added to buildings and bus stops by entirely or partially covering them with vegetation.
A growing medium can be positioned on top of a waterproof membrane to benefit birds, bees, and butterflies. Beyond these, cities should prioritise incorporating water features with naturally vegetated shorelines that slant gradually, providing essential access for birds and other wildlife.
Authorities should ensure that all new construction projects adhere to sustainable practices by incorporating environmental assessments into the building plan approval process. This requires collaboration among government authorities, developers, architects, and communities. Public awareness and education are key to fostering a culture of environmental stewardship. Educational institutions should integrate sustainability and wildlife conservation into their curricula to prepare future generations to prioritise these issues.
Securing funding for eco-friendly projects can be challenging, but innovative financing mechanisms, such as green bonds and climate funds, offer promising solutions. International organisations and development banks should support these initiatives with grants, loans, and technical assistance.
Our actions today will shape the preservation of our ecosystems and the well-being of future generations. By addressing the impact of micro-barriers and embracing sustainable practices, we can create a resilient and biodiverse future, ensuring a more harmonious coexistence between development and nature.
Dr Sultan Ahmed is the Associate Director at Bangladesh Institute of Governance and Management (BIGM), Former Secretary of the Power Division, Former Chairman of Rajdhani Unnayan Kartripakkha (RAJUK), and Former Director-General of the Department of Environment.
Hurmetun Nesa Labiba is a Research Intern at Bangladesh Institute of Governance and Management (BIGM).
Disclaimer: The views and opinions expressed in this article are those of the author and do not necessarily reflect the opinions and views of The Business Standard.
