An intertidal zone is an interface between sea and land; it comprises a variety of different landscapes, from rocky beaches through to gentle sandflats and mudflats. Due to the tide advancing and receding twice a day, the environmental conditions of the landscape are constantly changing. Thus, the intertidal zone ecosystem is unique, especially as it is designed to withstand these variations. However, any disruption to the ecosystem puts it under threat – climate change-related impacts are having a large impact, along with threats from tourism, pollution, and coastal development.
The turns of the tidal action
A typical intertidal zone ecosystem consists of various animal and plant types, including barnacles, mussels, seaweed, and sandworms, which thrive within the zone. However, other species also utilize the zone temporarily, either for food or as a seasonal habitat – these include fish, shrimp, seals, and migratory birds. In these ecosystems, the tide advances and recedes twice a day, meaning that the environment undergoes rapid variation in temperature, moisture, and salinity. It is also frequently hit by strong winds and waves. Organisms have therefore evolved to be suited to this harsh environment. For example, barnacles and mussels fill their shells with seawater to survive the low tide. Fish and shrimp species take refuge during low tide in any rockpools, or pools of water formed on expanses of mud and sand.
The intertidal zone ecosystem sees greater biodiversity in different parts of the zone, depending on how much of the day an area is covered in seawater. The three different parts are high tide, middle tide, and low tide. Since the high tide zone is covered in water for a small part of the day, it is exposed to warmer temperatures and drier conditions, and thus sees fewer plant and animal species. However, since low tide parts are covered in water for much of the day, they are more suitable for aquatic life and therefore see far greater biodiversity than the rest of the zone. The intertidal zone ecosystem is an interconnected web of different animals and plant species that depend on each other for survival, and some species travel up and down the zone for food, or to escape predators – this means that none of the zones should be developed on, or disrupted, in order to maintain a healthy ecosystem.
A range of factors is increasingly putting intertidal zone ecosystems under threat. Climate change-related impacts, from stronger storms through to sea level rise, have the ability to remove habitats and displace animals from their natural habitat. For example, climate change has started to increase the frequency and strength of storms; intertidal zone ecosystems struggle to withstand these changes. Over the past few decades, tourism in coastal areas has put greater pressure on using beaches for recreation, thus scaring away many animal species, and thereby disrupting the ecosystem. A recent upsurge in coastal development directly disrupts ecosystems by building on habitats and entire inter-tidal zones. Furthermore, the occurrence of chemical and oil spills has increased as the world becomes more industrialized; these seriously harm intertidal zone ecosystems, often killing many animals. Litter pollution is also a huge problem, with large pieces of plastic, metal cans, and polystyrene harming animals.