Ted Williams wrote a piece this week for Yale Environment 360 on the impact climate change is having on the Delaware Bay. Although this estuary is much smaller than the Chesapeake Bay (782 square miles to the Chesapeake’s 64,299 square miles), the two watersheds have a lot in common, in terms of geographic location, features, and marine and shorebird species. The changes Williams sees occurring in Delaware Bay are either issues we are currently seeing in the Chesapeake, or could be a sign of changes to come.
The most dramatic change occurring in the Delaware Bay is the loss of tidal wetlands due to sea level rise and erosion. The watershed is losing an acre a day of its wetlands. With rate loss expected to increase, by 2100, 90% of these wetlands may be lost.
Wetland loss impacts lifecycle processes of several species. Atlantic menhaden larvae require tidal marshes. Ribbed mussels (an important filter feeder in the Bay) form tight-knit clusters in marshes; erosion makes the mussels more susceptible to predation.
Sea level rise contributes to beach erosion and shoreline tree loss. Horseshoe crabs, which use beaches in the Delaware Bay watershed as spawning grounds, are losing their grounds to sea level rise. Some shorebird species dependent on horseshoe crab eggs, such as the red knot, are at risk from these environmental changes.
Certain species in the Delaware Bay may see short-term benefits from climate change. With fewer freezes occurring, Delaware Bay oysters can survive in intertidal zones. However these now warmer zones are hosts to diseases (MSX and Dermo) and predators (oyster drills).
Warmer waters exacerbate pollution issues. Nutrients build up, dissolved oxygen can decrease, and algal blooms can increase in frequency.
The Chesapeake Bay is also experiencing shoreline loss and erosion. Places like Dameron Marsh and Hughlett Point in Virginia have been discussed here previously in terms of erosion and sea level rise. Naturally warmer waters in the Bay mean that diseases such as MSX and Dermo have been impacting native oysters for decades. It will be interesting to see how warmer waters -associated with climate change- host new or increased populations of pests/predators for our oysters. Ocean acidification may also be a concern. The changes occurring between species relationships, such as between Delaware’s red knot and horseshoe crab, will certainly be something to look out for in this watershed.
To read Ted Williams’ article, please visit e360.yale.edu.
This past Saturday, I joined the Women’s March in Washington, D.C. While I marched for a number of social justice issues, one of my primary concerns in today’s world is climate change, and the preservation of the scientific community. Since this is a blog dedicated to the Chesapeake Bay, I would like to remind readers of the threats climate change pose to the Bay and the greater watershed.
Sea Level Rise:
Sea level rise is one of the most well known impacts associated with climate change. The most recent projection from climate scientists (March 2016), foresee global waters rising by two meters, or over six feet, by 2100. Sea level rise is already having severe impacts in the region, particularly on Smith and Tangier Islands in the Chesapeake. I visited both islands in 2011, and saw – more noticeably on Smith Island- major portions of the island inundated with water. Although sea barriers can delay impacts, waters are rising on the islands by about 2 feet each year. It is estimated that Smith Island will be completely underwater by the end of the century.
Sea level rise is especially potent in this region due to the natural sinking of land at the southernmost part of the Chesapeake Bay watershed. We’re seeing the biggest impact on our islands, but coastal towns and cities are facing sea level rise as well. Because of climate change and land subsidence, the Hampton Roads area for instance, is “experiencing the highest rates of sea level rise along the entire U.S. East Coast,” (WRI, 2014).
Coastal Flooding & Shoreline Erosion:
Related to sea level rise are the issues of coastal flooding and shoreline erosion. Sea level rise contributes to shoreline erosion and leads to an increase in flooding incidents. Cities in Southeast Virginia will be especially vulnerable to increased coastal flooding events (VIMS, 2012). Cities further north in the watershed are seeing a rise in coastal flooding events too. Annapolis reports that floods occur ten times as often as they did in the 1950s (CBP, 2016).
Miles of coastline along the southern Chesapeake region have been eroded; sea level rise may be playing a part (see former post here on Dameron Marsh and Hughlett Point).
Ocean acidification is the acidifying of marine waters as the ocean absorbs carbon dioxide (CO2) from the atmosphere. It is unclear how much of the Bay watershed will be impacted by acidification, however acidification could impact several species in the Bay. Shellfish make their shells out of calcium carbonate. As waters absorb CO2, and water chemistries change, certain shellfish face difficulties building their shell. This is true for the Eastern oyster found in the Chesapeake Bay, whose shells would become more brittle in acidified waters, and leave them more vulnerable to other threats.
Oysters are making a major comeback in Virginia, but the oyster farms and the restaurants that have emerged around this industry in recent years would face the biggest economic losses if and when Bay waters become more acidic.
Scientists are still studying how ocean acidification will impact the blue crab population in the bay (studies are being undertaken at institutions like UMCES). Crabs form their shells differently than oysters, and acidification may actually strengthen the shells of blue crabs. However, a researcher at UMCES has found that juvenile crabs grow more slowly in acidic waters. Given that juvenile crabs are threatened by other environmental issues in the Bay- such as the loss of seagrass habitat- ocean acidification could play a part in reducing blue crab population numbers.
Temperatures of regional bodies of water have been rising in correlation with rising air temperatures. Over the past 50 years, stream temperatures in all six Bay states (NY, WV, DE, MD, PA and VA) and in Washington, D.C. have risen by an average of 1.2 degrees F and up to 2.2 degrees F (CBP, 2016; EPA, 2016). This may not seem like a major increase to us, but it can be to marine species. Warming waters – even seemingly small increases in temperature- can contribute to dead zones and algal blooms. Cold-water fish species are more likely to be displaced by fish that thrive in warmer waters. Warmer waters can also impact fish and plant growth and reproduction.
Scientific studies – including data collection and modeling- play a crucial role in understanding how our climate is changing, and how our environment and wildlife will respond to these changes, both in the Chesapeake Bay watershed and beyond. We must continue to support the collection of data and dissemination of scientific reports on our environment.
Maryland’s Smith Island and Virginia’s Tangier Island, both in the Chesapeake Bay, are rapidly losing land due to sea level rise, erosion and storm damage. I last visited the islands in 2011 for a school field trip. Smith Island seemed to be especially suffering from land loss. Many properties were flooded and front yards covered in standing water. Talking to the residents, many were worried about the rising waters coupled with a disappearing local economy. What little jobs were left revolved around harvesting seafood; most residents have to commute to the mainland for work (Crisfield), while many of the younger generations had moved off the island permanently in search of better prospects.
Tangier Island is struggling with the same land loss issues, although from what I observed, seemed to be a small step ahead of Smith Island. At the time Tangier had a seawall built around the more heavily inhabited part of the island, while Smith Island had no effective means of holding back the encroaching waters. In November of 2012 Tangier was approved state and federal funds to have a jetty built to protect their harbor- a $4.2 million project (source: Washington Post). According to a Bay Journal article released Sunday, Smith Island has recently been awarded funds for a similar project. Smith Island will be getting $15 million from the federal government’s Sandy relief fund. Money will be split between financing a breakwater project, jetty and dock repair on the island. Will the money save these Chesapeake islands from sea level rise and land loss, or is it just delaying the inevitable?
Last week I shared a project on the state of the Eastern oyster, which included a review of restoration efforts in the Chesapeake region and a study on the potential impact of ocean acidification on the oyster population. As I mentioned in this report, acidification has had a major impact on the West Coast oyster industry, but has not yet had much of an effect on the East Coast. It is difficult to predict how the Chesapeake Bay will be affected by acidification, given the unique estuary that the Chesapeake is. The Bay is a mix of freshwater and saltwater, and salinity and depth vary across the estuary. Although many reports on ocean acidification exist, there are very few studies that have been conducted on acidification on coastal systems.
I learned today of a professor who has been studying the issue of acidification, and its effect on species native to the Chesapeake, such as the Eastern oyster and blue crab. Justin Ries works at the Marine Science Center in Northeastern University in Boston, and has been growing oysters and blue crabs in the lab. The organisms have been raised in water with high levels of carbon dioxide, to mimic possible future conditions on the East Coast. The results don’t look so promising for the now growing Chesapeake oyster industry. (See a 2010 Earth Magazine write-up here).
However, as mentioned, there is uncertainty as to the extent acidification will affect the Chesapeake. More studies must be conducted on coastal estuaries to be able to predict future conditions. In the meantime, representatives in the state of Maryland are attempting to bring this issue up for further study, examining the effects of acidification, and possible solutions, to be included in a report by the Maryland Department of Environment next year, (Maryland House Bill 118). Hopefully other states, especially Virginia, will follow suit.
I’m sharing a project I worked on last spring on oyster restoration in the Chesapeake Bay, and the impact ocean acidification may have on the oyster industry in the coming years. Ocean acidification is caused by the uptake of carbon dioxide from the atmosphere, and affects the ability of organisms, such as oysters, to form shells. Acidification has already caused problems for oyster farmers on the West Coast, and could become an issue in our region.
In this project I examined the decline of the oyster population in the past century, looked at the current restoration effort, and researched the potential effect ocean acidification could have on the eastern oyster. I reviewed literature on the issues, including journals, articles and webpages, and then wrote a short reflection piece. Reviews, comments, questions or critiques are welcome.
U.S. Carbon Emissions Rose Last Year: (The Washington Post)
Study of Tides Measures Global Average Sea Level Rise: (NYT The Flood Next Time) Sea level rise and sinking land affecting East Coast, especially Chesapeake Bay islands