Estuary Information PDF

Estuary What is an Estuary? An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Importance of Estuary 1. Habitat Estuaries are vital habitats for...

Estuary What is an Estuary? An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Importance of Estuary 1. Habitat Estuaries are vital habitats for thousands of marine species. These habitats can include oyster reefs, coral reefs, rocky shores, submerged aquatic vegetation, marshes, and mangroves. 2. Nursery Estuaries are often called the “nurseries of the sea” because so many marine animals reproduce and spend the early part of their lives there. 3. Water Filtration Estuarine habitats acts as enormous filters. It filter pollutants such as herbicides, pesticides, and heavy metals out of the water, as well as excess sediments and nutrients 4. Flood Control Wetlands function as natural sponges that trap and slowly release surface water, rain, snowmelt, groundwater and flood waters. Estuarine Habitats Estuarine Habitats 1. Beds of Sea-grass 2. Coastal Wetlands 3. Shellfish Beds 4. Tidal flats/ Mudflats 1. Beds of Sea-grass 2. Coastal Wetlands Wetland types found in coastal watersheds include salt marshes, bottomland hardwood swamps, fresh marshes, mangrove swamps, and 3. Shellfish Beds 4. Tidal Flats/ Mudflats Mudflats refer to land near a water body that is regularly flooded by tides and is usually barren (without any vegetation.) Classifications of Estuary Classification of Estuary based on: A. Geomorphology the study of the physical features of the surface of the earth and their relation to its geological structures. B. Water Balance is the second most important characteristic of an estuary. It is simply the sum of water sources minus the sum of the water losses C. Hydrography the science of surveying and charting bodies of water, such as seas, lakes, and rivers. A. Geomorphology  Lagoon/ Bar- A. Geomorphology built estuaries form when a barrier island or sand spit separates a body of water, often called a lagoon, from the open Lagoon/ Bar- built  Fjord A. Geomorphology Area of relatively shallow, quiet water situated in a coastal environment and having access to the sea but separated from the open marine conditions by a barrier. They have moderately high river input and little tidal mixing. Fjord  Classical Coastal A. Geomorphology Plain Are those that formed as sea-level rose and filled existing river valleys. This common type of estuary, also called a drowned- river valley, is found along all US coastlines, Coastal Salt Marsh A. Geomorphology also known as a coastal salt marsh or a tidal marsh, is a coastal ecosystem in the upper coastal interti dal zone between land and open saltwater or br ackish water that is regularly flooded by the tides.  Tectonic Estuary A. Geomorphology estuaries form when a section of land drops or tilts below sea level due to tectonic processes such as folding and faulting of rocks. Freshwater and seawater flow into the down-dropped area to create this Tectonic Estuary B. Water Balance Positive In positive estuaries the evaporation from the surface of the estuary is less than the volume of freshwater entering the estuary from rivers and land drainage. Negative In negative (or inverse) estuaries the opposite situation exists, with evaporation from the surface exceeding the freshwater runoff entering estuary Neutral Type of estuary in which neither the freshwater inflow nor the evaporation predominates; freshwater inflow + precipitation = evaporation. C. Hydrography  Salt Wedge C. Hydrography occur when the mouth of a river flows directly into salt water. The circulation is controlled by the river that pushes back the seawater. Partially Mixed A. Geomorphology Partially mixed estuaries have a tidal flow that provides a means of erasing the salt wedge. The salt water is mixed upward and fresh water is mixed downward.  Completely C. Hydrography Mixed Well-mixed estuaries have strong tidal mixing and low river flow that mix the sea water throughout the shallow estuary. The mixing is so complete that the salinity is the same top to bottom and decreases from the ocean to the river. uman Impacts on stuary 1. Pollution- Agricultural run-off, plastics, chemicals, oil spills 2. Habitat destruction- due to coastal development, dredging activities 3. Overfishing and aquaculture 4. Climate change 5. Alteration of hydrology- due to dam construction and river diversions rotecting the Estuary Ramsar Convention on Wetlands National Estuary Program (NEP)