In the chilly waters beneath the Golden Gate Bridge, a magnificent gray whale breaches, a spectacle once rare in the currents of the San Francisco Bay. Its immense body, a ghostly apparition against the fog-laden skyline, rolls playfully in waters it historically bypassed.

Down the coast in the shallows of Monterey Bay, juvenile great white sharks dart with unnerving frequency, their sleek, powerful forms no longer occasional visitors but eerie fixtures, frightening unaware beachgoers.

The beaches too whisper tales of change. Velella velella, the delicate sailors of the sea, now carpet the coastline in surreal abundance, their blue, translucent sails, a stark contrast to the usual browns and grays of the sandy shores. This influx, as beautiful as it is bizarre, paints a picture of a changing ecosystem, driven by unseen forces beneath the waves.

These altered patterns are not merely shifts but signals of a deeper disturbance. The marine ecosystems of the Bay Area are sounding an alarm, one that resonates through the depths of the Pacific to its shores.

Recent observations show that the temperatures have risen from the low to mid-50s to a warmer 60 degrees Fahrenheit along the coast of the Bay Area. As ocean temperatures continue to inch upward, driven by marine heat waves and the impending threats of El Niño, the foundational dynamics of marine life are undergoing a profound transformation. This shift, while subtle in degrees, is monumental in its impact. The warmer waters disrupt the delicate balance of marine habitats including species like great white sharks, gray whales and, Velella velella.
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Kelp forest

Over the past decade and a half, the Bay Area has witnessed a significant shift in the distribution of great white sharks, particularly among juveniles. Traditionally, these juvenile sharks were confined to the warmer waters of Southern California and Northern Mexico, avoiding the cooler waters of Northern California due to their thermal sensitivity. However, since 2014, a notable change has occurred. The sharks have been found throughout Central California and in Monterey Bay. “We've had a series of warming events and as a result, the waters have been warmer on average and we've noticed these baby and small white sharks that were never found in this area have started to appear​​,” said Dr. Salvador Jorgensen, a marine ecologist at California State University, Monterey Bay.

This migration northward is not just a trivial shift but marks a significant change in the sharks' range. The sharks were historically confined in the south of Point Conception near Ventura due to the cold limit of their thermal tolerance (as juveniles, they don’t have enough body mass to develop and maintain heat). The juveniles, typically found in waters between 60 and 70 degrees, are now frequenting Monterey Bay, where water temperatures have risen above 60 degrees during marine heatwaves. This has led to increased interactions between these young sharks and the local marine fauna, particularly sea otters, whose numbers in Monterey Bay have dramatically decreased due to shark bites.

The arrival of juvenile sharks in Monterey Bay outside the typical white shark season, normally spanning from August to February, signifies how climate anomalies are reshaping marine habitats. These young sharks, needing warmer temperatures and feeding primarily on fish and stingrays, are altering the local food web dynamics. As Dr. Jorgensen said, “Predators have a disproportionate effect on the ecosystem,” and the influx of these juvenile apex predators is impacting species that have not adapted to such threats​​.

Moreover, the changing distribution of these sharks poses both challenges and unexpected benefits. While the expanded habitable range of juvenile sharks is aiding their population resilience, it pushes predators and prey into narrower areas, escalating conflict and reducing biodiversity. These interactions are complex and require critical conservation measures, particularly the reforestation of kelp, which provides a refuge for sea otters and supports a diverse marine ecosystem.

Reflecting on the future, Dr. Jorgensen is optimistic about the sharks’ adaptation to changing ocean temperatures but remains concerned about the broader ecological balance. “If we look at the ecosystem, the coastal ecosystem as a whole, I think there's some concern about the balance in the ecosystem for other species because these sudden changes in the distribution of large predators are having some unintended or unforeseen consequences.” This scenario is called a “range shift” and underscores the urgent need for a holistic approach to marine conservation that considers both the direct and cascading effects of climate change on marine life.

Gray whale spotting

In recent years, significant changes have also been observed in the behaviors and migration patterns of gray whales, particularly around the San Francisco Bay area. Clara Bird, a Ph.D. Candidate in the Geospatial Ecology of Marine Megafauna Lab in Oregon State University’s Marine Mammal Institute, said that while most gray whales continue to follow traditional migration routes, increasingly, some are venturing into areas where they have not commonly been seen before. “We're seeing whales exploring... and that could be a sign of a bigger change in the future,” said Bird​​.

There has been a marked increase in gray whale visits to San Francisco Bay since 2019, a shift from their historical behavior. “Traditionally, we'd spot a gray whale or two annually, but recently, they've not only increased in number but are also staying longer—from a day to several months,” said Bill Keener, a research biologist with the Cetacean Conservation Biology team at The Marine Mammal Center.

The changing migratory behavior is largely driven by climate change which affects the whales' traditional food sources. As Arctic ice coverage diminishes and ocean temperatures rise, the benthic crustaceans that gray whales typically feed on become scarcer. The scarcity results in gray whales being starved during their migration, forcing them to seek alternative feeding grounds, such as the San Francisco Bay. “With less food available in their traditional feeding grounds, they're attempting to feed in the bay, though it's less ideal and doesn't provide the same nutritional value,” said Keener.

The shift to new areas brings gray whales into closer contact with human activities, increasing the risk of ship strikes, entanglement, and exposure to pollutants. Keener emphasized the gravity of these encounters, “The gray whales, being shore whales, are particularly vulnerable as they migrate along busy coastal waters where they face threats from marine traffic and fishing gear.” Bird elaborated on the risks, “If whales are producing fewer calves because of increased stress from boat noise and other human interactions, eventually the population is going to decline.” Moreover, as these majestic creatures venture closer to shorelines, their presence can disrupt local ecosystems, particularly when they begin feeding on prey species that are not typically part of their diet.

Addressing the challenges faced by gray whales requires concerted conservation efforts. Bird suggests several measures, including regulations to reduce boat speeds in areas frequented by whales and fishing practice management strategies to prevent whale entanglements. Bird also stressed the importance of individual actions in contributing to marine conservation. Simple steps such as reducing plastic use, installing filters on washing machines to catch microfibers, and supporting research through donations can collectively make a significant impact. She also encouraged civic engagement: “Voting is a strong way to influence policy... align your vote with these issues if they matter to you.”

Breath-taking capture of the Bay Area coastal's kelp forests

The curious and captivating Velella velella, commonly known as by-the-wind sailors, are tiny marine hydrozoans that traverse the ocean's surface, propelling themselves with their stiff, translucent sail. In recent years, climate change has altered the life cycle and distribution of these delicate creatures. “A warming ocean, particularly in the winter with warmer than average water, seems to be conducive to Velella velella,” said Julia Parrish, a marine ecologist and professor at the University of Washington.

Just last month, thousands of these tiny creatures invaded the beaches of the Bay Area, transforming the sands into a blue translucent carpet. While this occurrence by itself isn’t rare, never have the by-the-wind sailors been seen in such large numbers. This phenomenon is due to marine heatwaves which have become more frequent and intense and impact the reproductive cycles and geographical distribution of Velella velella. The result is massive stranding events in which a multitude of these jelly-like creatures wash up along coastlines.

The ecological implications of these strandings are profound. Velella velella feed on zooplankton and small fish, including the eggs of coastal forage fish species such as herring, sardines, and anchovies. "Because there are so many of them, they can actually have an impact on other parts of the epi-pelagic zone," Parrish said, indicating how the large population can disrupt the marine food web dynamics​​.

For human communities, the consequences are mixed. While Velella velella are not directly harmful to humans—lacking the harmful stings of some of their jellyfish cousins like the Portuguese man o’ war—their decay on beaches results in a foul smell, deterring local beachgoers and tourists. Hence, the sight of beaches covered with these blue sailors can be both a marvel and a nuisance.

Local citizens play a crucial role in tracking these occurrences. Scientists by themselves cannot monitor the large number of beaches on the California coast, which is why help from beachgoers is much needed. Programs like COASST (Coastal Observation and Seabird Survey Team) empower local communities to monitor their coastal environments while they go for a stroll on the beach. “They report that to us... and it tells us a pattern,” Parrish explained, emphasizing the value of citizen data collection in understanding ecological changes​​.

As the Bay Area witnesses these profound shifts in its marine ecosystems, the urgent need for action becomes clearer. These occurrences suggest that in a warming world, the changing climate creates new winners and losers in every ecosystem. Warm conditions might result in more Velella as well as a larger habitable range for great white sharks, but it also leads to greater endangerment of gray whales and decreased sea otter populations. These alterations in migration patterns and behaviors serve as a stark reminder of the broader impacts of climate change on our ecological balance.
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