Our journey today begins in Upper Newport Bay located in Newport Beach, California. Within just a short walk through this bay one can experience a range of habitat types from coastal sage scrub to riparian to wetlands. The salt marshes nestled within the bay procures its water from the tidal influences of the Pacific Ocean as the tides rise (and fall) through the Upper Newport Bay channel where it fills the marsh daily. A salt marsh is a wetland and requires a water source and generally has different tidal inundations throughout the day. The amount of water a marsh receives will have a direct effect on what species thrive there, both indigenous (native) and colonial (non-native/invasive). The salt marsh is divided into different sub-habitats: the upper marsh, the middle marsh, the lower marsh, and the mudflats. Even within these sub-habitats, they can be further divided into distinct zonations according to species’ specific tolerances. Today, we will lead you through the four main subdivisions of the salt marsh.
The salt marsh is sandwiched by other habitats experiencing higher or lower elevations. Coastal sage scrub is oftentimes adjacent to the salt marshes in the Upper Newport Bay in the direction of higher elevation. Right beyond the higher elevation of coastal sage scrub, a small step will take you to an area called the “upper marsh.” Upon looking at the ground, you will notice how dry the soil is which indicates the lack of water from being beyond high tide. The most common plants in this habitat are going to be the Alkali heath (Frankenia salina) and shoregrass (Distichlis littoralis). As you look toward the open water within the marsh, you can see the surrounding area change with the smallest of elevation differences, which allows varying amounts of water to flow and saturate the soil. A marsh is filled with many different microhabitats and if you look closely you notice how subtle the changes are.
As you proceed deeper into the wetland, you will find you are now standing in the “middle marsh” you start to see more ground cover and little plants that are about 2-3 inches high. The plants you can clearly see here are pickleweed (Salicornia virginica), fleshy jaumea (Jaumea carnosa), salt wort (Batis maritima) and sea lavender (Limonium californicum). The native sea lavender, California sea lavender, has adapted so well to its climate in the marsh, it is able to survive with little water as well as the ability to survive underwater for small amounts of time when the tide comes in. Another adaptation these plants have is their waxy leaves which helps conserve the water it receives during dry periods. These plants also can tolerate high salt content in their water and have special adaptations to deal with removing or excreting salt from their systems.
Venturing further into the marsh, you will find that the “lower marsh” is very wet and squishy. The lower marsh receives a consistent flow of water throughout the day. The species located here can survive in a low-oxygen climate, meaning they have special adaptations to survive underwater. This is a harsh environment and many plants are unable to survive the constant presence of water and salt. One plant that manages to survive here is cordgrass (Spartina foliosa) which thrives near the mud flats -- the salt marsh zone at the lowest elevation. In the mud flat there is not much life except those who get swept in with the tide. The species that reside here the most are crabs and small fish that come in with the tide use the mud flat as shelter from potential predators. If they are not well hidden, they may eventually be predated upon by the native and migratory birds in the area. The salt marsh acts as an important habitat for many species of birds and mammals that either reside nearby or are migrating north and south throughout the year. Two of our important listed species are the Belding's Savannah Sparrow (Passerculus sandwichensis beldingi) and Ridgeway Rail (Rallus obsoletus), which rely on this habitat to survive.
A salt marsh is a supremely beneficial ecosystem that houses and protects native flora and fauna, many of which are threatened or endangered. Not only does the salt marsh help filter out debris and pollution that comes in from both the ocean and urban runoff, leaving behind cleaner water for animals and people but also creates a natural barrier that helps prevent potential storm surges from breaching into communities by absorbing the impact of the rising water. The increase in the rising tide has the potential to further impact the salt marsh and inland ecosystem in negative ways. If the tide continues to rise there is the possibility that the plants adapted there will not survive the increase in water which will then decrease the system’s biodiversity. If that happens, then there would be a displacement of these mammals that rely on the salt marsh as a food source. Ways we help improve the conditions of the marsh include picking up debris and trash that will negatively impact its environment and taking incremental steps to reduce our carbon footprint. As a society, it is necessary to realize the importance of a salt marsh habitat and its systems and how it functioning properly helps improve its community for both plants and animals as well as people. To read more about the ecosystem services provided to us by wetlands, read a past blog post here.