There is a risk of losing the indispensable roles of crocodiles and relatives

Gharial creates a “raft” for Crocodillian young. Credit: Phoebe Griffith

As alligators become more at risk of extinction, these iconic species aren’t the only ones we stand to lose. New research in the Journal of the British Ecological Society Functional ecology It also highlights that the unique roles these reptiles play in their ecosystems are at risk.

Creating shelter for other animals through unique nesting systems and fighting invasive, agricultural pests are two important services that the world’s crocodiles and alligators will lose if they are not better protected, according to new research by ZSL (Zoological Society of London). ).

Up to 38% of the diverse ecological functions crocodile species provide to wider ecosystems are at risk of being lost, researchers say in a first-of-its-kind study.

was published Functional ecology, the study identifies crocodile, alligator, caiman and gharial species most in need of conservation measures. They each play important, but different and varied roles in the ecosystems they live in, and the authors call for greater conservation of these highly threatened species based on their unique ecologies.

The study explores the diversity of crocodilian ecological roles by looking at measurable traits related to how the species functions in their environment, such as skull shape, body size and habitat use. By developing a database of these key features for all species, the researchers revealed often-surprised ecological functions of crocodiles.

From the prolific mining of the critically endangered Chinese crocodile (扬子賄; Alligator sinensis), which provides vital shelter and refuge for other species, to controlling agricultural pests such as the Philippine crocodile (Crocodylus mindorensis, locally known as Buwaya). , eating the invasive apple snail; crocodiles are vital engineers of the ecosystems in which they live. Some, like the world’s largest crocodile, the saltwater crocodile (Crocodylus porosus), travel hundreds of kilometers in the open ocean, traversing critical terrestrial, freshwater and marine habitats to transport nutrients between ecosystems.

More than half of all crocodiles are threatened with extinction due to habitat loss, hunting, fishing and damming of rivers. The loss of these endangered species means that we will lose the diverse ecological roles they provide, with unknown and potentially devastating ecological consequences.

There is a risk of losing the indispensable roles of crocodiles and relatives

The Miniature Chinese Alligator digs elaborate burrow systems and can survive the coldest winters of any alligator species. Credit: James Hennessy, National Reptile Zoo

Researchers from ZSL’s Institute of Zoology (IOZ) and the EDGE of Existence programme, the University of Oxford’s Wildlife Conservation Research Unit and the Gharial Ecology Project in India have discovered that certain species, such as critically endangered animals, have unique ecologies. gharial (Gavialis gangeticus). The gharial is an aquatic species specially adapted to live in water, its long and narrow nose is ideal for catching fish – its main prey. Its presence is an indicator of clean and healthy water systems.

ZSL Ph.D. student and lead author Phoebe Griffith said: “Many people think of crocodiles as the large predators that catch zebras in wildlife documentaries, but this is only a small part of the behavior of one species. There are about twenty-eight species of crocodiles, and they have evolved to be surprisingly different from each other. they did

“Measuring the different ecological roles of these species is an important factor in understanding and conserving global biodiversity and looking at the scale of what we would lose if these key players were to disappear.”

“If we lose these species, we’ll lose the important roles they play forever. We’re only just beginning to explore what those roles are, but some species may be lost before we have a chance to understand their place in their ecosystems. This is especially worrisome because many of the crocodilians we’ve ecologically distinguished are also immediate descendants. are endangered species”.

Six of the 10 species with the most unique ecological functions are critically endangered and are so depleted that they are considered functionally extinct in most of their historic range. Two endangered species, the gharial and the Chinese crocodile, are also highly evolutionary unique and have been highlighted as priority EDGE (Evolutionarily Distinct and Globally Endangered) species by ZSL’s EDGE of Existence programme. The study found that conservation of endangered crocodilians based on their evolutionary uniqueness would also have a positive impact on maintaining the functional diversity of species worldwide.

EDGE Postdoctoral Research Scientist, Dr. Ricky Goombs said: “From miniature burrowing alligators to giant sea-dwelling crocodiles, the vast evolutionary journey of crocodilians has produced a dazzling variety of shapes, sizes and behaviours. Unfortunately, the world’s rarest crocodilians are in decline and on the brink of being lost forever, along with their functions in their ecosystems. .

“However, our research shows that by prioritizing the rarest species for conservation efforts, we can preserve much of the diversity we are losing. Interestingly, by preserving the evolutionary history of crocodiles, we can effectively protect their endangered functions. In fact, looking back, we we can effectively protect crocodile diversity and the benefits this diversity provides to ecosystems into the future.”

There is a risk of losing the indispensable roles of crocodiles and relatives

Brown and colleagues discovered this Philippine crocodile eating invasive apple snails, an agricultural pest in the Philippines. Credit: Joseph Brown

Since 2017, ZSL has been working to protect the ecologically rarest crocodile, the gharial, in India and Nepal. With project partners in Nepal, more than 40 gharials have been radio-tagged to provide vital information on why this species is so endangered. In addition to confirming breeding in Nepal’s Bardia National Park, ZSL works with local, fish-dependent communities to develop sustainable fishponds, conduct research, monitor and protect nesting sites, and map river use outside the protected area.

A recent EDGE fellow working with the ZSL-supported Gharial Ecology Project in India is studying the seasonal movements and breeding behavior of wild resident gharials in the Chambal River. species globally.

Now working with gharials in northern India as part of the Gharial Ecology Project, co-author Dr. Jeffrey W. Lang commented: “Humans are the key to crocodile conservation. If we value the presence of these dinosaur relatives around us, then conserving the world’s alligators, caimans, crocodiles and gharials will be a priority.

“Studying them and understanding how important these aquatic predators are where they still live is a necessary first step in conserving not only the most impressive crocodiles, but also their many interesting and diverse lifestyles. Village community gatherings and environmental programs schools crocodiles too is critical for local information and assessment of all wetland types, including

Research also shows that certain traits help reduce a species’ risk of extinction; species that invest heavily in reproduction, are highly adaptable to different habitats, or can tolerate extreme climatic conditions have a higher chance of survival. Crocodiles often occupy naturally fragile habitats such as freshwaters and coastlines that are under high human pressure. As many species with different ecological functions and high risk of extinction are located in and around Asia, the study highlights the continent as a source of threat to them.

Phoebe concluded: “Our research highlights the highly threatened nature of crocodilians and that immediate, stronger conservation measures are essential for many of these species if we are to preserve their ecological function in the freshwater environments where they occur. This is just as important as freshwater habitats. Place are among the most threatened on the face of the earth, but they provide many essential services for our planet.”

Gharials that lived in Bronze Age China help clarify the history of crocodiles

Phoebe Griffith et al, Using functional traits to identify conservation priorities for the world’s crocodilians, Functional ecology (2022). DOI: 10.1111/1365-2435.14140

Provided by the British Ecological Society

Quote: Irreplaceable roles of crocodiles and relatives at risk of being lost (2022, August 5) Retrieved August 7, 2022 from

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