Mangroves, mullets, humpback whales: 3 new science stories you should know about

Humpback whale

Humpback whale in Tahiti. (© Photo Rodolphe Holler)

Protecting nature starts with science. Here’s a roundup of recent policy-relevant science published by Conservation International experts.

  1. Invasive fish species may be better equipped for a changing climate

Native species already have to compete with invasive new species, but now climate change is creating even more challenges. According to a new study, an invasive species in Hawai‘i may be better suited to a changing climate than its native counterpart.

The invasive kanda mullet was accidentally introduced to Hawai‘i in the 1950s when it was unknowingly mixed into a shipment of Marquesas sardines that were released into Hawaiian waters. This isn’t a new problem: Invasive species have been introduced into ecosystems for thousands of years, competing with native species for food and habitat — and sometimes eliminating them entirely. The invasive kanda mullet is rapidly overtaking native mullet species in the estuaries across the Hawaiian Islands, due in large part to its biology: It reaches the age of reproduction faster and reproduces more often than native mullet species.

This is especially important during times of extreme weather that may prevent mullets from spawning. For the native mullet, extreme conditions may lead to delayed or skipped spawning; whereas the kanda mullet need only wait until the next month. Because of this, the kanda mullet often outnumber its native counterparts in Hawai‘i, competing for resources and literally crowding native mullet out due to its massive population size.

“Mullet species are vital to the diet of people in the Pacific Islands, Asia and Africa, and understanding their biology and life cycle is essential to support the management of this invasive species,” said Eva Schemmel, science adviser for Conservation International Hawai‘i and a co-author of the study published in February in Environmental Biology of Fishes.

Preventing ecosystems from being overtaken by invasive species is key to maintaining their health. As climate change is likely to shift habitat ranges for multiple species, studies such as this one that help us understand how to mitigate the impacts of and adapt to these shifts are vital.

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  1. Endangered humpback whale species may adapt to warmer waters 

Climate change could prevent endangered Oceania humpback whales from using their traditional breeding and resting grounds, a new study found.

Oceania humpback whales are found in waters in the South Pacific and are the only endangered humpback whale species in the world. They require a specific temperature range for breeding (22-28° C or 71.6-82.4° F), and climate change will raise ocean temperatures beyond that range in much of their breeding grounds. Instead of the lagoons the whales currently favor for breeding and resting — shallow waters that are particularly susceptible to temperature rise — researchers hypothesize they will begin using underwater mountain ranges known as seamounts, which have lower surface temperatures.

This insight into how global warming could affect suitable habitat will help determine the best management practices to protect whales in the future. For example, the creation of “no-go areas” in the new breeding grounds would ensure whales can nurse their calves without disruption from human activity.

“We want to make sure we reduce any potential pressures on the whales so that we are creating a fit and healthy population that can adapt to climate changes that we can’t control,” said Olive Andrews, marine program manager of Conservation International Asia-Pacific and co-author of the study, published in Global Change Biology in January. “Oceania humpback whales are a vital focus of the tourism industry for islands such as Tonga and Niue, and this economic importance coupled with the fact that they are still a recovering population means that managing their habitat correctly is absolutely crucial.” 

  1. Putting a price tag on mangroves may help save them

In one of the most biodiverse regions of Colombia, the national government has proposed building a port within the protected area of the Tribuga-Corrientes cape, on Colombia’s northern Pacific coast. This port would destroy mangroves and the ecosystem services (that is, the tangible benefits that nature provides) that local communities rely on.

A new study puts an exact price tag on the cost of destroying those mangroves: If the port is built, it would cost US$ 230 million per year in lost ecosystem services such as providing habitat for fish, protecting the coast from storms and storing carbon.

Plans for the port have been discussed for close to a decade, and local organizations have been trying to stop it for just as long with little success. To prove the detrimental impact that the port — and by default, the destruction of the mangroves — would have on the economy, the researchers analyzed the value of the mangroves through three distinct lenses: monetary (the economic value to fisheries, other natural resources, etc.); sociocultural (the value to surrounding communities); and ecological (storing carbon, biodiversity, etc.).

By putting a price tag on mangrove ecosystem services, researchers are able to show the mangroves’ economic importance not only to surrounding communities, which rely on fishing, agricultural and tourism that the mangrove forest provides, but to the country at large.

The data from this study was presented to the president of Colombia, senators and the Ministry of Environment with the goal of stopping the construction of the port.

“Mangroves are vital for human well-being and provide valuable ecosystem services to the country as a whole,” said María Claudia Díazgranados of Conservation International Colombia and an author of the study, published in the Journal of Environmental Economics and Policy in March.

“Our goal with this study is to provide solid evidence that the port will harm the country economically more than it would help it. Hopefully this is enough to stop the progression of the port in Congress and save the mangrove forest and all of the benefits that it provides.”

Olivia DeSmit is a staff writer for Conservation International. 

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