OCEAN CITY — The Maryland Coastal Bays Program released its annual report card for the estuaries in and around the resort area with an overall grade of C+, although some regions continued to do better than others and there are still reasons for concern.

The comprehensive C+ score for the entire coastal bays watershed for 2013 was the same score assigned in the prior year. The MCBP report card unveiled last week showed slight improvements in some indicators, particularly in the Chincoteague Bay, but continued to indicate serious phosphorous problems throughout all of the sub-bays behind Ocean City and Assateague. Local, state and federal partners help create the detailed annual assessment on the health of the back bays using rigorous monitoring results to derive a science-based score.

From north to south, the Assawoman Bay behind Ocean City received a grade of C, which was the same grade it received in 2012, but it showed slight improvement in some indicators. However, while there were improvements in dissolved oxygen and hard clams, declines in phosphorous, chlorophyll a and seagrass impacted the 2013 score.

The St. Martin River continued to show the poorest results in most indicators in the 2013 report, which assigned it a grade of D+. While its 2013 score was similar to its 2012 grade, the St. Martin River had lower scores for nitrogen, phosphorous, chlorophyll a and seagrasses than any other region in the coastal bays. Most indicators scored poor or very poor, with the exception of chlorophyll a, which was good, and dissolved oxygen, which was moderate.

The Isle of Wight Bay earned a solid C in the 2013 report. Improvements in dissolved oxygen and chlorophyll a were offset in the report by declines in phosphorous, hard clams and seagrass scores. Hard clam scores in the Isle of Wight Bay were good to very good, while dissolved oxygen, phosphorous and seagrasses were poor to very poor.

The Sinepuxent Bay continued to lead all of the other sub-estuaries in the 2013 report and again received the highest overall grade of all of the regions. Nitrogen and chlorophyll a were both excellent, while dissolved oxygen, phosphorous, hard clams and seagrasses earned moderate scores. Hard clams in the Sinepuxent improved from a poor score in last year’s report.

The Newport Bay continued to be disappointing and received the lowest score (D+) of all of the sub-watersheds. Improvements in nitrogen, hard clams and chlorophyll a were offset by declines in dissolved oxygen, phosphorous and seagrass beds.

One of the real success stories in the 2013 report was the Chincoteague Bay, which continued to improve in most indicators after declining for several years and earned a solid B-. Small declines in chlorophyll a, hard clams and seagrasses were offset by larger improvements in dissolved oxygen, nitrogen and phosphorous. One indicator that continues to be a concern in the Chincoteague Bay is hard clams and the region continues to receive the lowest score. According to the report card, the continued decline in hard clams in the Chincoteague Bay may be the result of recurring brown tides.

One category that appeared particularly alarming was the continued decline of seagrass beds in the coastal bays. Seagrass beds declined for the fourth year in a row and the current acreage in the bays is only at 28 percent of the established goals. Seagrass beds peaked in 2001 when the acreage totaled 71 percent of the established goal. In 2013, the Maryland portion of the Chincoteague Bay suffered the greatest loss of seagrass beds including 500 acres. Meanwhile, the Assawoman and Newport Bays lost 50 percent of their seagrass beds last year. The losses are significant because seagrasses are critical fish habitat, especially for juvenile fish and crabs.

Beginning in 2002, water monitoring stations throughout the Chincoteague Bay began to show increases in nitrogen and especially phosphorous, which contribute to the decline of seagrass beds throughout the estuary. For example, since 2002, the Chincoteague Bay has lost almost 11,000 acres of its more than 16,000 acres of seagrass beds due to warmer temperatures and increasing nutrient levels. Grasses now cover only about 5,400 acres in the Chincoteague, or about 24 percent of the program’s goal.

Coupled with brown tide blooms in the Chincoteague, the loss of seagrass beds spells trouble for an area once considered one of the most pristine in Maryland. While the northern bays are still in relatively poorer condition than the southern bays, work to remove point sources and control stormwater has paid some dividends north of Route 50 and in Newport Bay, where water quality has actually improved somewhat. However, water quality only passes the nitrogen thresholds at 45 percent of the sites and phosphorous thresholds at less than one percent in the coastal bays. Poor water quality and higher temperatures have decreased seagrasses by 75 percent across the estuary in recent years.