The Littoral Ecosystem

Natalie Schafer and Emily Maranga

The littoral ecosystem, also known as the littoral zone, is a very diverse ecosystem. Littoral zones are usually located near lakes, ponds, seas, and rivers and extend from the shoreline to partial water submersion. The longest littoral zone in Europe is along the coast of Greece. It is longer than 18,000 km (~11,185 mi). The way to determine where the littoral zone ends and the next zone, the limnetic zone, begins is by the amount of light penetrating the water. In a littoral ecosystem, light reaches the sediment level under the water. This combined with plentiful nutrients and dissolved oxygen creates the perfect breeding ground for aquatic plants. 

Littoral ecosystems require plants that can survive when partially or totally submerged under the water. Species that tend to thrive in these conditions are algae, seagrass, and fungi. One specific type of seagrass that is often present in the littoral zone is eelgrass. It has the ability to store nutrients which are abundant in this zone for later development. Other types of flowering submerged aquatic vegetation, such as the water lily and the American lotus, are able to store air and grow up towards the surface so that they can receive more light. Kelp is another species found in the littoral zone with an interesting adaptation. It has strong roots that allow it to stay in the ground even when there is a strong current. Some lichen can be found in the rocky parts of the littoral zone because they have the ability to store water and prevent drying out, while also being able to make food through photosynthesis. All species that are present in the littoral zone must be able to adapt to the varying amounts of sunlight and water coverage, but also the dynamic climate that comes along with that. The climate of littoral ecosystems can vary greatly! For instance, in ponds and lakes in the summer, the bottom can reach 4 °C (39.2 °F) and the top can reach 22 °C (71.6 °F). In the winter, the bottom can be 4 °C (39.2 °F), while the top is 0 °C (32 °F). This would mean that there is a layer of ice on the surface of the water. In between the top and the bottom of the water, the water is continuously circulating because of winds and can create a constant temperature. Overall, the littoral zone tends to be warmer than the bottom of the lake or pond because it is receiving more heat from the sun. 

Animals Found in the Littoral Ecosystem
Similar to the plants found in the littoral zone, animals also have to be well adapted to survive this environment. Many of the species that inhabit these areas are invertebrates. For instance, crabs are able to survive predators and the heat from the sun because they are small enough to hide in the plants, under rocks, and in the sand. The same goes for snails and limpets that are found in the littoral zone. Other species that are able to move to seek shelter and safety are mud shrimp and various types of worms. The ability to be mobile in the littoral zone is extremely important for staying out of harm’s way. Some species such as barnacles and mussels are immobile and are much more vulnerable and at a higher risk of getting eaten. They are able to latch on to solid material and not get washed away by tides, but if they are in the reaching distance of a predator, they will get eaten. Some find a way to cement themselves higher up on tall structures (e.g. tree trunks and dock pillars) and store water in order to survive the heat and avoid aquatic predators. 

The predators in a littoral zone are species that are on land or in the water. As the tide goes out, birds, foxes, walruses, and humans are significant threats to the invertebrates on the shore. One of the most recognizable predators may be the seagull. Once the target is in sight, they swoop down and grab it from the sand. Predators that are found in the water are often seastars, fish, and sea anemone. Many of the fish that inhabit the littoral zone must be small or only live in the littoral zone temporarily. For instance, perch usually grow to be about 19.1 cm (7.5 in) so they use the aquatic plants in the littoral zone to lay their eggs. Other fish such as sculpin and darters also lay their eggs in the littoral ecosystem but are small enough to stay there in the shallow waters. Sculpins only grow to 3.5 cm (1.4 in) and darters average around 7.62 cm (3 in). Burbot is another fish species that are present in this environment but only when they are juveniles. When the eggs hatch they are quite small, but burbot can grow to 80 cm (32 in) and will migrate to larger waters with increased depth. This cycle loops once again when mating season returns and burbots return to shallow water for spawning.

Issues within the Ecosystem
There are many benefits that come with having a healthy littoral ecosystem; especially when they neighbor residential areas and urbanized land. Some would argue that the benefits include  economic ones since they help in raising property value and are aesthetically pleasing to the eye. However, something that many people do not recognize is that these littoral zones are a vital habitat for biodiversity and ecological functioning. 

The littoral ecosystems provide wildlife habitat and support water quality and erosion control. According to Lake and Wetland Management, in most areas, littoral zones are required for lakes that are larger than one acre and deeper than six feet. Unfortunately, even if these zones are required by law, these ecosystems are abused and are subject to both natural and human threats. 

When focusing on issues stemming from human activity, a major issue is pollution. Disregarded trash, runoff (chemicals, fertilizers), sewage spills, and septic systems, as well as other human-made substances or excess amounts of nutrients negatively impact the ecosystem and its wildlife. These pollutants give off toxins that alter an ecosystem and its ecological purpose. For instance, one issue that is causing algal blooms is trace amounts of nitrogen and phosphorus; excessive algae growth (eutrophication) is stimulated by the nitrogen in the water. The overabundant amounts of algae deplete the oxygen in the water, killing off the organisms living there. This nutrient pollution can oftentimes come from agricultural runoff, runoff from urban areas, and wastewater treatment facilities. These sources can also release toxic chemicals into the water. The problem with this is that the organisms ingest these chemicals and it bioaccumulates in the food chain. This means that as time goes on, the levels of chemicals increase as smaller fish are eaten by larger fish. Eventually, humans eat the large fish and are ingesting many toxic chemicals.  

Another issue related to human disturbance is recreational activities.  Boating and overfishing impede on the littoral zone and harm flora and fauna. Invasive species are also a threat to the flora and fauna of the littoral zone. When these species are brought in by humans, they create competition and often win. Since they do not have any known predators in these new areas, they often survive and rapidly grow. This reduces the amount of food and shelter available to the native species and results in the death of many indigenous creatures. 

Another direct threat from humans is large scale fishing. When boats are moving through these areas, the plant and animal species are physically disturbed and destroyed. These boats often use a method of fishing called trawling where a large net is dragged through the water, often along the floor. The net pulls up many plants and catches many of the animals mentioned earlier. Anchoring from these boats also can destroy much of the ecosystem. 

An additional threat is ocean acidification.  Due to the elevated levels of carbon dioxide in our atmosphere as the result of our carbon footprint, the concentration of the absorbed carbon dioxide in our atmosphere and waters increased dramatically. As a result, water becomes more acidic and, therefore, alters the marine, aquatic, and neighboring ecosystems. Certain plant and animal species are not able to survive in these highly acidic environments, thus causing a downward spiral for biodiversity in the littoral zone. Therefore, ocean acidification also impedes on the ecological functioning of the littoral zone.  

Finally, climate change is a huge threat to animals in the littoral zone. As temperatures rise, the surface of the water gets hotter and the water levels rise. Many of the species that were adapted to survive the specific conditions of the littoral zone are unable to adapt quickly enough to changing environments. Along with this, climate change also brings along a lot of storms that can destroy and bring pollution to the littoral ecosystems that threaten the lives of many organisms.The littoral ecosystem already has a complex ecosystem which is necessary for species that have adapted to their niches. With the current climate experiencing intense storms and extreme temperatures, many elements of the ecosystem are struggling to survive.  Storm surge and winds cause damage to the flora that is responsible for filtering the water that enters the aquatic ecosystem, and certain habitats within this ecosystem cannot withstand the severe weather conditions.  Climate change has also increased the risk of droughts and floods – depending on location. It is important to recognize and take action against these issues within the littoral ecosystem because if these littoral zones are disrupted, they are not able to properly function to help maintain both the terrestrial and aquatic ecosystems that they are between.  

Policies Addressing the Issues
With the various threats that continue to impact the littoral zone, some policies have been put in place to help mitigate these issues.  These U.S. policies include, but are not limited to, the Natural Resources And Environmental Protection Act (NREPA), the Marine Life Protection Act, the Environment Quality Act, and the Coastal Area Management Act.  

NREPA, was implemented by the state of Michigan in 1994. Michigan’s littoral and aquatic ecosystems were being severely influenced by invasive species and human disturbance. In order to restore and protect these environments, the state of Michigan came together to develop a policy that would address these ongoing concerns and to enforce the necessary authoritative measures to ensure ecological health. The purpose of this policy was to implement penalties for violations of the Invasive Species Order and maintain the Prohibited and Restricted Species list (Michigan Department of Natural Resources).  In addition, this act protects the ecosystem(s) and the state’s natural resources through monitoring of hunting and fishing, as well as regulating discharge (pollutants) that enters the aquatic environments.  

The Marine Life Protection Act is supported by the National Park Service. Specifically, in the state of California, this act has been implemented to protect its vast marine life. Though the act is specified for marine species, it also addresses the protection that benefits the littoral zone since this ecosystem plays an important role in maintaining the health of the aquatic and marine ecosystems.  The Marine Life Protection Act protects all forms of marine life including species of economic and commercial value. This act has been well established in California, and effective measures have been established to solidify that the goals and objectives of the Act are met.  

Unlike the Marine Life Protection Act that does not specifically apply to littoral zones, Canada has implemented a policy under its Environment Quality Act of 1999 which includes a Protection Policy for Lakeshores, Riverbanks, Littoral Zones, and Floodplains.  This policy helps ensure the “sustainability of water and watercourses,” “ protection of […] littoral zones,” and to “preserve and maintain the quality and biodiversity of these ecosystems (CanLII). They also plan to “promote the rehabilitation of degraded riparian zones using the most natural techniques” that are accessible and affordable.  Riparian zones can overlap with littoral zones. Riparian zones are terrestrial areas that border aquatic environments (e.g. river banks) and are often the first areas impacted by flooding. Protection and restoration of the riparians will further benefit the littoral ecosystem under this Environmental Quality Act.    

Lastly, the Coastal Area Management Act of 1974 was established in North Carolina in response to the “increasing pressures […] [of] expanding in industrial development, in population, and recreational aspirations” (North Carolina Environmental Quality). Commercial and recreational uses harm the coastal environments, including the littoral zone. North Carolina implemented the Coastal Area Management Act into its new management plan to “ensure the orderly and balanced use and preservation of our coastal resources”  (North Carolina Environmental Quality).  The management plan not only provides protection and conservation of “water use, scenic vistas, and fish and wildlife” , but it also accounts for the needs and desired recreational activities that the people seek in these coastal habitats.  This Act also highlights the proposed management of urbanized areas and areas of significant intrinsic value.

What can you do: Coastal Cleanups
Clean up after yourself and others! The Earth’s oceans and other aquatic ecosystems already have enough plastic in them – they do not need anymore.  To help benefit the environment and your community, pick up your trash and other belongings instead of leaving them to be washed up into the littoral zone or pulled out to sea.  These plastics and other discarded materials can cause injuries, sickness, and even death to the flora and fauna. When you go for a hike or a stroll on the beach, bring a bag and some gloves with you and leave the area better than you found it.  If you are feeling more inspired, organize a coastal cleanup for your community!

Refuse, Reduce, Reuse, Repair, Recycle
Reduce the amount of trash you and your family produce every day. A number of plastics and other non-environmentally friendly materials wash up and interfere with the plants and animals in the littoral zones.  Plastic bags can become entangled in the aquatic plants that help filter the incoming water; and styrofoam can interfere with the amount of sunlight that these species require to survive.  Instead of purchasing and continuing to support the plastic industry, switch to more sustainable materials: glass, metal, clay, or wood.  These materials can be reused multiple times and can limit the amount of plastics that threaten the environment.  Transitioning to these “green” materials can also benefit you – there is no need to worry about ingesting microplastics. 

You can also make a difference by engaging with organizations that strive to protect littoral zones. Programa Restauración de Tortugas Marinas (PRETOMA) is a Costa Rican non-profit civil association focused on assisting sea turtles which utilize littoral zones to lay eggs and return to the ocean waters. Organizations like Ocean Conservancy encourage coastal cleanups and have been hosting international coastal cleanups for over 30 years. Initiatives like these assist in keeping Earth’s waters clean of debri which can be toxic or lethal to animals throughout the littoral zone and beyond. Other groups, such as the Natural Resources Defense Council (NRDC), also aid in managing the welfare of the littoral zone as they strive to support wildlife in rivers, lakes, and coastal waters. Connecting with these organizations, or those with similar values, can provide opportunities for you to make a difference yourself. 

Sources: Biology Dictionary, CanLII, Climate Policy Watcher, Deep Sea Conservation Coalition, Defenders of Wildlife, Institute of Marine Conservation, Lake and Wetland Management, Michigan Department of Natural Resources, Michigan Legislature, National Park Service, National, Resources Defense Council, NOAA, North Carolina Environmental Quality, Ocean Conservancy, Science Direct, The Climate Reality Project