<\/a>\n\t\t\t<\/div><\/figure><\/a>\n\t\t\t<\/div><\/figure>\n\t\t<\/div>\n\nThese two examples of seaweed pressings were made decades ago. The red algae was collected in about 1929 near Friday Harbor, Washington. The kelp Macrocystis<\/em> was collected near Pacific Grove, California, in 1892. Photos courtesy of the Monterey Bay Aquarium<\/span><\/p>\n In a new study<\/a> published this past June, researchers from the Monterey Bay Aquarium examined a collection of dried, pressed seaweeds\u2014dating back over 140 years\u2014to learn what ocean conditions in the bay were like in the early 19th century.<\/p>\n Working with colleagues from Stanford University\u2019s Hopkins Marine Station in California, and the University of Hawai\u2018i, aquarium researchers gathered pressings of seaweeds collected from Monterey Bay between 1878 and 2018 and performed a variety of chemical analyses on their tissues.<\/p>\n \u201cWe were working with old and beautiful specimens, so we tried to take the smallest samples possible,\u201d says Emily Miller, the lead author of the study, who now works as a research technician at the Monterey Bay Aquarium Research Institute.<\/p>\n Despite the fact that some of the specimens were old and \u201ca bit leathery,\u201d Miller and her team were able to determine their amino acid and protein compositions, heavy metal concentrations, and stable isotope ratios.<\/p>\n The algae\u2019s nitrogen stable isotopes were of particular interest to the researchers. Algae absorb nitrogen, phosphorus, and other nutrients from seawater like sponges. When nitrogen is abundant in their environment, it is reflected in the nitrogen content of their tissues.<\/p>\n The researchers analyzed the nitrogen stable isotopes from pressings of Gelidium<\/em>, a type of red algae, and compared it to records dating back to 1946 of upwelling\u2014an oceanic phenomenon in which wind moves warm surface water away from the coast, driving cold, nutrient-rich water up from the deep.<\/p>\n The changes they observed in the Gelidium<\/em>\u2019s nitrogen isotope concentrations between 1946 and 2018 correlated strongly with historical records of upwelling, which suggested that the nitrogen isotope concentration of each piece of pressed algae was a direct reflection of the amount of upwelling that occurred during its growth.<\/p>\n Techniques for preserving seaweed specimens by pressing them have changed little over the decades. This sample of Gelidium<\/em> was collected in the 1980s. Photo courtesy of the Monterey Bay Aquarium<\/p><\/div>\n Knowing this, the researchers were able to use algal specimens to create a record of upwelling in Monterey Bay starting in 1878, extending the existing record back by nearly 70 years.<\/p>\n In doing so, the researchers uncovered new information about the sardine fishery collapse in the 1950s that devastated Monterey\u2019s Cannery Row, whose once-thriving canneries and colorful people inspired John Steinbeck\u2019s novels Cannery Row<\/em> and Sweet Thursday<\/em>.<\/p>\n The researchers found evidence that in the years leading up to the fishery\u2019s collapse, upwelling in Monterey Bay was decreasing\u2014likely due to climatic oscillations. This, combined with overfishing and other factors, they say, caused Monterey\u2019s sardine stock to crash.<\/p>\n Understanding how changes in upwelling impacted fisheries of the past could improve the way fish stocks are managed today says Kyle Van Houtan, chief scientist at the Monterey Bay Aquarium and coauthor of the study.<\/p>\n<\/a>