Biodiversity—the variety of life on Earth—is key in supporting the complex processes that keep ecosystems healthy, stable and productive, according to a new study from an international team of researchers.
Conserving biodiversity has clear benefits for the plants and animals themselves, as well as the people that rely on these ecosystems and the services they provide. And many studies have found that biodiversity can boost a single function of an ecosystem, such as plant growth or nutrient filtering. But according to Jonathan Lefcheck, lead author of the study and post-doctoral research associate at the Virginia Institute of Marine Science (VIMS), this research is the first to look at how biodiversity supports the suite of complex, interconnected processes essential for a healthy and functioning ecosystem.
Researchers analyzed 94 experiments conducted around the world to examine the relationship between biodiversity and ecosystem health. Their findings show that greater species diversity can benefit multiple functions of an ecosystem. “In other words,” said Lefcheck in a release, “as you consider more aspects of an ecosystem, biodiversity becomes more important: one species cannot do it all.”
A key example of these relationships can be found close to home, in the underwater grass beds of Chesapeake Bay. “Seagrasses are home to a variety of small animals that perform different jobs,” said Lefcheck. “Some control algae that would smother seagrasses. Others keep out invasive species. Still others provide food for striped bass and blue crabs that are served on our dinner tables. By conserving this variety of animals, we can maximize the health of the grass bed, and the benefits to people.”
The study is available through the online journal Nature Communications.
Representatives from states across the Bay region recently signed a cooperative accord that will help reduce the amount of nitrogen flowing from onsite wastewater systems into local waterways.
At the Chesapeake Bay Program office last week, representatives from Delaware, Maryland, Pennsylvania, Virginia and West Virginia signed a Memorandum of Cooperation to share data related to the performance of advanced pretreatment technologies for “onsite wastewater treatment systems,” often called septic systems. Pretreatment of wastewater allows for the removal of potentially harmful pollutants such as nitrogen—but these technologies are often costly, and their approval takes time. Under the arrangement, information-sharing across states will help expedite the approval and deployment of these technologies, as well as offer cost savings to manufacturers and consumers.
Onsite septic systems account for less than five percent of the nutrients flowing to the Bay; advanced pretreatment technologies are expected to reduce nitrogen from these systems by at least 50 percent, as compared to conventional systems. Improvements in wastewater treatment will help achieve the clean water goals of the new Chesapeake Bay Watershed Agreement, which encompasses the Chesapeake Bay Total Maximum Daily Load (TMDL).
If you’ve ever watched a solitary ant explore your countertop, you might have marveled at its tiny size. You also might have questioned how something seemingly insignificant can be such a nuisance in your aspiringly sterile kitchen. Then you remember what your tiny pioneer heralds — the impending arrival of thousands of her sisters — and she suddenly seems like a more formidable adversary.
At a few millimeters short of a typical carpenter ant, microplastics are another case of both extreme smallness and overwhelming magnitude. Microplastics are the fragments, pellets, sheets, fibers, microbeads and polystyrene that begin as improperly discarded plastic bottles and trash that get washed into our waterways. At less than five millimeters in length, they are nearly imperceptible. But plastic doesn’t degrade like most organic material, meaning the total amount of plastic in the environment doesn’t really change as it breaks down, allowing microplastics to persist in most surface waters around the globe, including the Chesapeake Bay.
University of Maryland Professor Dr. Lance Yonkos is the primary author on a study of microplastics collected from four tributaries of the Chesapeake Bay — the Patapsco, Magothy, Rhode, and Corsica Rivers. Of the 60 samples taken by the National Oceanic and Atmospheric Association (NOAA) Marine Debris Program, all but one contained microplastics.
To Yonkos, it’s not really a surprise there are microplastics in the Bay.
“We have many of the prime sources for creating and introducing microplastics to aquatic environments,” Yonkos said. Roads are a main contributor because they promote physical degradation of plastics and provide easy transport via storm drains to Bay tributaries. Yonkos listed wastewater treatment plant effluent and substantial shipping traffic.
As plastic fragments become smaller, a greater number of animals are able to swallow them—as exemplified by the recent case of a whale killed by a shard from a DVD case. When these materials break down enough reach the level of microplastics, even filter feeders like oysters can consume them.
Smaller pieces also mean more surface area, Yonkos said, which could mean more leaching, either of chemicals from the plastic itself or of the environmental contaminants that cling to its surface.
“In this way, microplastics might serve as a vehicle for introducing bioaccumulative contaminants to the food chain,” Yonkos said. The concentration of such toxic contaminants can become magnified at higher levels of the food web.
But, the science isn’t clear yet on whether microplastics represent a serious environmental or human health concern.
“Since we don’t really know yet, it is a little disconcerting to think that most of the plastics we have created over the past 70 years are still in the environment,” Yonkos said.
And microplastics are here to stay. With no feasible method for removing microplastics that are already in the environment, measures like improved recycling and decreased use of offending products — like those that include microbeads, which would be banned by the state of Maryland according to legislation passed recently — could improve the situation going forward.
“The take home message is prevention,” Yonkos said. “If we want to reduce microplastics in the oceans we need to limit their release at the source.”
To view more photos, visit the Chesapeake Bay Program's Flickr page.
A new report from an advisory committee of scientific experts recommends the Chesapeake Bay Program’s Watershed Model be adjusted to better account for the influence of stream corridors and tree canopy on pollution from urban areas.
In the report, experts from the Bay Program’s Scientific and Technical Advisory Committee (STAC) suggest accounting for the effects of stream corridors and urban trees to improve the model’s accuracy and allow managers to better target pollution-reducing best management practices.
Trees and stream corridors interact with nutrient and sediment pollution in ways that are unique compared to other urban land covers, the study suggests. The erosion of stream channels can significantly increase the amount of sediment pollution associated with an urban area, while trees can help reduce the volume of polluted runoff.
The Watershed Model is used by Bay Program partners and stakeholders to estimate the amount of nutrients and sediment reaching the Bay. The model currently includes three urban land use categories: impervious (paved) surfaces like buildings, roads or parking lots; pervious (porous) surfaces like lawns or landscaping; and construction sites.