Kelp forests are disappearing

Fishing communities along the coasts of Baja California and California were hit in recent years by the sudden disappearance of the marine kelp or sargassum forests that fed lobster and abalone populations, among many species in the region. The kelp forests collapsed due to a combination of climate change and the uncontrolled proliferation of the purple sea urchin plague. Victor Rodriguez reports on how this marine disaster came about and what is being done to rescue these needed sargassum forests.

Beneath the Pacific Ocean lies a marine ecosystem teeming with life. Located on the west coast of the United States and the Baja California peninsula, among other marine regions, sargassum forests, better known by the Anglo-Saxon term kelp, provide habitat for countless species in a trophic web that ultimately benefits humans.

Classified as the largest among the algae, it stands out for its brown coloration with characteristic greenish tones and its stems covered with air-filled vesicles that serve as floats. They cling to the ground at depths of up to 30 meters, growing towards the surface in search of sunlight. Their dissemination generates an underwater landscape like few others: authentic forests that serve as feeding areas, nurseries and refuge for crustaceans, fish and marine mammals alike.

Its presence is recorded on the Pacific coasts of North America -from Alaska to Baja California-, on the coasts of South America, Australia and New Zealand.

In addition to its ecosystemic value, its link to the local economy is well known. The foundation of several Mexican fishing communities is directly linked to the presence of kelp forests. Lucrative fisheries such as lobster, abalone and red sea urchin in Baja California and Baja California Sur have sustained generations of fishermen.

Despite their ecosystem and economic importance, kelp forests often go unnoticed in the environmental policy framework. Many factors impact the health of kelp forests: from abrupt temperature changes, to the presence of kelp-eating wildlife, to sewage pollution, have all had a detrimental impact on their presence.

One of the main factors affecting kelp is the abrupt changes in temperature, especially the marked rise in temperature.

These have been pronounced as part of the effects of global climate change, impacts that have the scientific community on alert. A major impact occurred between 2014 and 2016.During these years an atypical temperature increase occurred, which they dubbed as “Blop”, of up to 3 degrees Celsius, which meant a direct impact on many of the existing kelp forests, motivating their decline to minimum levels.

According to scientific monitoring, the most affected regions are located off Bahía Asunción and Natividad Island in Baja California Sur, but it also impacted kelp forests in Todos Santos Bay, Baja California, around the islands, and in the seas off San Diego and Monterey, California. The disappearance of vast extensions of marine forests generated a domino effect that caused a decrease of 15 to 58% in lobster, red urchin, abalone and sea cucumber populations, according to a study led by Juan Carlos Villaseñor, Nur Arefeh and Fiorenza Micheli. This reality has reduced the quality of life of several fishing communities that depend on these fishery products for their livelihoods.

There are also anthropogenic factors, that is, those generated by human presence, that directly affect the health of marine forests.

A notorious and well-documented one in Baja California is the exponential spread of the purple urchin, a species that feeds insatiably on sargassum.

Without species to control the population of the spiny crustacean, coupled with its low commercial value, this resulted in a trophic imbalance that devastated the marine forests, leaving in its place a barren soil of purple spines.

Currently there are important efforts to reforest kelp forests with promising results on the coast of California, USA, and in Baja California, Mexico. International scientific cooperation has been vital in sharing experiences and techniques that have supported the protection and reforestation of these important marine forests on which so many coastal families depend.

This report is part of the “When the Creek Dries Up” Series, funded in part by The Walton Family Foundation.