thumb|right|A map showing the location of Cape Cod Bay.
thumb|Cape Cod, Cape Cod Bay, and Massachusetts Bay, north is oriented to the right in this photo taken from the International Space Station on
thumb|Cape Cod Bay from a beach in [[Dennis, Massachusetts|Dennis.]]
Cape Cod Bay is a large bay of the Atlantic Ocean adjacent to the U.S. state of Massachusetts. Measuring below a line drawn from Brant Rock in Marshfield to Race Point in Provincetown, Massachusetts, it is enclosed by Cape Cod to the south and east, and Plymouth County, Massachusetts, to the west. To the north of Cape Cod Bay lie Massachusetts Bay and the Atlantic Ocean. Cape Cod Bay is the southernmost extremity of the Gulf of Maine. Cape Cod Bay is one of the bays adjacent to Massachusetts that give it the name Bay State. The others are Narragansett Bay, Buzzards Bay, and Massachusetts Bay.
History
In 1524, Italian navigator Giovanni da Verrazzano was the first European to discover Cape Cod Bay, his claim proved by a map of 1529 which clearly outlined Cape Cod. In 1620, the Pilgrims first sheltered in Provincetown Harbor where they signed the Mayflower Compact, the first democratic document signed in the New World. Surface water stratification and mixing have a distinct seasonal cycle in the Bay. In the winter, the density of bay water is nearly the same from top to bottom, allowing it to mix readily and become nutrient-rich all around. Stratification occurs when the surface water becomes warmer and less thick than the deeper water in the spring, summer, and early fall. There are 53 saltwater embayments along this extensive stretch of coastline, each of which is formed by a depression or dip in the coastline that forms a bay abutting the ocean.
Fishing season typically takes place between May and October. Although plenty of fisherman prefer to fish from shore rather than a boat, Massachusetts requires a Recreational Saltwater Fishing Permit for anyone 16 years of age or older.
Many coastal towns have fishing piers, and boat charters that provide daily trips into Cape Cod Bay to catch fish. The most popular bait used is sea clams, and live mackerel.
Threats to Cape Cod Bay
Pollution and water quality
Per the Cape Cod Commission, the bay is experiencing water problems. Although nutrients like nitrogen are an important aspect of aquatic ecosystems, excessive amounts can damage water systems. Cape Cod's estuaries are vulnerable to the effects of excess nitrogen due to a number of factors. Nitrogen is poisoning the saltwater barrier that has characterized the peninsula. On Cape Cod, centralized wastewater treatment plants are not extensively employed due to the expense and challenges associated with widely spread housing, as well as huge seasonal fluctuations in population due to summer tourists. Typical backyard sewage systems, which are not aimed at eliminating nitrogen, are responsible for an estimated 80% percent nitrogen dumping on Cape Cod Bay. The circumstances it generates devastate animal habitat and frequently violate water quality requirements, resulting in fish kills and decreased shellfisheries, among other things. The consequences of this pollution must be carefully managed. Another big issue affecting our coastal waters is polluted runoff. Contaminants collected up in precipitation and melting snow are eventually dumped into the bay, resulting in this sort of pollution. Fertilizers and other lawn and garden chemicals, pet waste, salt from streets, and oil and gasoline leaking from autos are all possible contaminants picked up in runoff.
Harmful Algal and Cyanobacteria blooms
Pollution's effects have already been seen in our coastal waters. Excess nutrient input from both point and non-point sources leads to high levels of plant growth, in addition to the direct, harmful impacts of pollution. This process, known as eutrophication, is taking place in Cape Cod Bay to some extent. In the bay, excess nutrients originate mainly from human sources and activities, such as waste systems for example. With the harmful increase of these nutrients comes an increase in algae and bacteria. Phaeocystis blooms are common in Cape Cod Bay during the spring. particularly near the town of Brewster, and are a unique environment. They are the widest expanse of tidal flats in North America, rivaled in the western hemisphere only by a similar expanse in Brazil.
View
thumb|left|800px|Cape Cod Bay from space