Water Quality's Impact on Seabirds in Monterey

Monterey Peninsula, renowned for its unique landscape and ecological abundance, attracts countless tourists every year. As tourism flourishes along the coastline, concern for biodiversity and seabirds’ habitat deserves more attention. This article will introduce common seabirds found in Monterey, their features, the challenges they face, and how residents can contribute to their preservation.

Water quality is defined as the measurement of chemical, physical, and biological characteristics against the requirements of a specific use. Its physical features include temperature, turbidity (cloudiness), color, odor, and taste, while its chemical properties include PH level, dissolved oxygen, hardness, and the presence of heavy metals. Biological factors, such as bacteria and viruses, are also important in water quality assessment. Common water quality concerns in coastal areas include increased turbidity, warming sea temperatures, and plastic ingestion, which can lead to diseases in animals' digestive systems. Though this information may seem abstract and distant, local Monterey seabirds living around us face these challenges. 

For Stevenson students, the most common bird observed on campus is undoubtedly the Western Gull. With a white head and body and a typical yellow bill with a notable red spot, it has nearly become a coastal landmark. They hover above our school dining hall, land on the Rosen Amphitheater, and leave adorable footprints on the beach. Yet beneath their cute appearance, they can be extremely aggressive during territorial invasions and prey on fledglings of other species. Their main diet comes from human refuse, suggesting their tight connection with humans and urban areas.

 Changes in water quality play little role in impairing Western Gulls because they spend most of their time scavenging in urban areas. However, the continued loss of their habitats deserves more attention. As demonstrated in a study on birds’ digestion, 92% of pellets (undigested food that birds cough up through their mouth) contain artificial items, and 79% of them are plastic. 

The Brown Pelican is another typical bird species in Monterey. Its gular pouch and big maroon-brown body are two distinguishable features. The male’s neck and head are usually white, sometimes the latter with a pale yellow hue. The neck will change to brown during the breeding season, and pink skin will appear around its eyes. Parents breed their chicks together, and they glide over the sea surface to prey on fish and amphibians.

Water quality suggests a stronger impact on them compared to the Western Gull, and the challenges they face have drawn attention worldwide. According to ABC News published on May 4th, Pelicans are threatened by severe food shortages arising from global warming; as the sea temperature rises, fish scatter and stay deeper than they normally do, which increases the foraging difficulty for Pelicans. At the International Bird Rescue Center, staff are caring for about 20 pelicans suffering from starvation; this also happened in 2024, when the number of pelicans enduring starvation exceeded 100. The water turbidity doesn’t play a critical role in their survival, since their main food source is fish from the shallow area, which doesn’t demand much clarity.

Different from the previous, the Brandt’s cormorant, which features a notable blue patch on their throat, is known to be a good diver. “They can dive deeper than 200 meters with their unique body traits: their inner wings maintain insulation, which keeps their body temperature stable, while the outer part absorbs and repels water for acceleration,” according to the staff at the Pacific Grove Museum of Natural History, where I visited for this article.  

 The increased turbidity significantly affects cormorants’ underwater foraging. From a study investigating cormorants´ visual ability, the result suggests the formula: y=3.71x+7.6, where x represents the water turbidity, and y represents the minimum object width cormorants can perceive underwater. Based on this formula, the higher the water turbidity, the bigger the object needs to be to be perceived, therefore indicating reduced visibility for Brant’s cormorants. 

Learning the root of water quality degradation is essential for us to contribute to seabirds’ preservation. In this research, the most common pollution source is runoff from rainfall and irrigation water that carries contaminants such as plastic and heavy metals from urban areas into the ocean. Overfishing and climate change also impact the ocean to some degree. Residents can protect the local environment with small moves, including buying sustainable food, reducing plastic use, and reducing their carbon footprint.