sites

Artificial Reefs As Havens For Marine Predators | Earth Wise

October 28, 2020 By EarthWise Leave a Comment

Climate change, pollution, development and other stresses have accelerated the decline of reef ecosystems across much of the world’s oceans in recent years. Large predators such as sharks, mackerels, barracudas, jacks and others that formerly fed around reefs have had to venture outside their normal migratory routes in search of suitable alternatives.

According to a new study by Duke University, marine predators have taken up residence at shipwrecks and other artificial reefs. The study surveyed 30 sites along the North Carolina coast and found that predator densities were up to five times larger at the 14 artificial reefs surveyed than at the 16 natural reefs in the survey.

Shipwrecks, particularly those that rose between 4 and 10 meters up into the water column, were a big favorite of the fishes. Some of those sites supported predator densities up to 11 times larger than natural reefs or low-profile artificial reefs. The shipwrecks are basically high-rise timeshares in the sea.

The findings of the survey show that artificial reefs can support large predators, supplementing natural reefs if the design and placement of the artificial reefs are appropriate. In addition, when it comes to designing artificial reefs, there appears to be a height advantage. So, reefs either made from sunken ships or at least made to resemble them would be desirable.

Because undersea predators help maintain healthy and sustainable populations of species lower in the food web, providing suitable habitat for the predators is extremely important. Based on the study, it appears that the strategic use of artificial reefs can be an effective way to help counter the increasing loss of natural habitat on the ocean bottom.

**********

Web Links

Artificial Reefs Take on a Towering Presence as Havens for Marine Predators

Photo, posted July 29, 2014, courtesy of NOAA Photo Library via Flickr. Photo credit: Flower Garden Banks National Marine Sanctuary

Earth Wise is a production of WAMC Northeast Public Radio.

Climate Change and Komodo Dragons | Earth Wise

October 12, 2020 By EarthWise Leave a Comment

The Komodo dragon is the world’s largest and most iconic lizard. Growing up to 10 feet long and weighing up to 360 pounds, Komodo dragons are endemic to five islands in southeast Indonesia, four of which are part of Komodo National Park, as well as a fifth that has three nature reserves. Komodo dragons have existed on earth for at least four million years, and it’s estimated that 4,000 of them survive in the wild today.

But according to a new study by researchers from the University of Adelaide and Deakin University in Australia, Komodo dragons could soon be driven to extinction. The research team found that the impacts of both global warming and sea level rise are likely to cause a sharp decline in available habitat for Komodo dragons. Current conservation strategies are not enough to avoid climate-driven Komodo dragon population declines.

The study, which was recently published in the journal Ecology and Evolution, involved close collaboration with Komodo National Park and the Eastern Lesser Sunda Central Bureau for Conservation of Natural Resources.

Climate-change-informed decisions should be a common part of conservation practice. According to the research team’s conservation model, Komodo dragons on two of the five Indonesian islands are less vulnerable to climate change. But those two islands might not be enough for the survival of the species. Conservation managers may need to translocate Komodo dragons in the future – to sites where these animals have not been found for decades – in order to protect the species from extinction.

Without taking immediate action to mitigate climate change, the research team says many range-restricted species like Komodo dragons are at risk of extinction.

**********

Web Links

Climate change threatens Komodo dragons

Photo, posted August 6, 2016, courtesy of Tony Alter via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

More Trouble For Monarchs | Earth Wise

April 14, 2020 By EarthWise Leave a Comment

Monarch butterflies have been in trouble for quite a while and now it seems like their prospects are worse than ever. Multiple surveys of butterfly populations are reporting plummeting numbers.

Western monarch butterflies spend their winters on the central California coast. Months later, they breed in California’s Central Valley and as far north and east as Idaho. But in recent years, it has become harder and harder to find them in their breeding sites.

The Western monarch population was in the millions in the 1980s. In 2017, an annual survey found 200,000 butterflies. In 2018 and 2019, only about 30,000 butterflies were tallied. The loss of Western butterflies in general has come about from a variety of factors, including development, climate change, farming practices and the widespread use of pesticides by farmers and on home and business lawns.

Scientists use the area of land that migrating Monarchs occupy in Mexico to gauge populations. This year, they covered about 7 acres, down from 15 acres in 2019.

Meanwhile, there are also far fewer Eastern monarch butterflies on the opposite side of the country. According to a new population survey, the Eastern monarch has passed the extinction threshold. Its population in 2020 dropped 53% from its already low 2019 numbers. Scientists were expecting lower numbers this year, but they were staggered by their findings.

Butterfly populations are quite variable, so it is possible that the drastic declines this year are not necessarily irreversible, but the news is not good. Researchers and environmental advocates continue to point out that mitigating the climate crisis, reducing pesticide use and planting pollinator gardens could help the butterflies to recover.

**********

Web Links

Monarch Butterfly Populations Are Plummeting

Photo, posted September 7, 2017, courtesy of C. Watts via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Smarter Prospecting

November 18, 2019 By EarthWise Leave a Comment

The global demand for copper and gold continues to grow. Copper is widely used in building materials, plumbing, and electronics. Gold is still highly valued for jewelry and coinage, but nearly a third of the world’s gold is now used in electronics.

Both of these metals are getting increasingly difficult to find as many of the known sources have been exhausted. Companies spend millions of dollars drilling deeper and deeper in search of new deposits.

It costs about $400 to drill one meter into rock and it is not uncommon to drill to depths of one to two kilometers. So, it can cost nearly a million dollars to drill a hole that has no guarantee of success. Given that ore deposits are tiny compared with the totality of the search space, prospecting for these metals is very much like looking for a needle in a haystack.

A researcher at the University of South Australia has developed a suite of geochemical tools to more accurately target valuable mineral deposits and thereby save drilling companies millions of dollars. The goal is to have drilling for valuable minerals be faster, cheaper and more environmentally friendly.

By mapping out where key chemical elements are found in greater concentrations, the new suite of tools greatly increases the chances of finding an ore deposit at a target site and thereby greatly improve the return on investment for exploration companies. The tools have been successfully tested at an iron oxide-copper-gold deposit in the north of South Australia, leading to a four-fold increase in the known footprint of their ore body. Finding economically viable enriched ore sites can generate both revenues and jobs.

**********

Web Links

Prospecting for gold just got a lot easier (and cheaper)

Photo, posted April 21, 2005, courtesy of Adam via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Dirty Air In The National Parks

August 27, 2018 By EarthWise Leave a Comment

Our national parks are supposed to be places that allow us to commune with nature. They offer incredible vistas and amazing sights. As a result, millions of Americans and visitors from around the world are drawn to these places – too many millions, in fact.