Tide pools are quite possibly the most compelling place in the ocean for a few reasons -- they're easily accessible if you're there at the right time of day, they contain an incredible amount of biodiversity among the flora & fauna, and, unfortunately, they are also a place where the effects of climate change and human impact can be startlingly apparent. Ed Ricketts, the inspiration for the character "Doc" in John Steinbeck's Cannery Row, could arguably be credited with bringing the magic of tide pools mainstream.

Ricketts recognized significant changes in the tide pools along Monterey Bay's coast as he spent day-in and day-out collecting samples and studying the marine life. He pushed forward the idea of watching the changes here, along the shore, as a way of knowing if everything was in balance, and his book Between Pacific Tides is practically required reading for any marine biologist these days. Now more than ever, the lessons Ricketts illustrated are important for us to understand. Tide pools are phenomenal places, but they're also at risk.

Jaymi Heimbuch

How Climate Change Affects Tide Pool Ecosystems

Global climate change affects tide pool life in at least three significant ways: rising sea levels, ocean acidification, and warmer water temperatures.

Changing Water Temperatures

As the world heats up, so too does the ocean. Just as happens with species on land, as the water temperature changes, plants and animals have to move around to adjust. On land, researchers have noted how plant and animal species are moving to higher elevations to escape warmer temperatures. The same is true with tide pool creatures. For instance, a new invasive sea slug is taking over Marin County tide pools, gobbling up the native sea slug populations as it moves north from it's southern habitats.

Phidiana hiltoni, an invasive sea slug. Marlin Harms / Flickr / Creative Commons

Researchers from UCSD report, "More notably, the sea slug's range expansion appears to be an example of how basin-scale climate change can affect local ecosystems. Up until recently, the "killer" nudibranch was basically considered a Southern and Central California species, with the heart of its range in places like Laguna Beach in Orange County. It was documented north of the Monterey Peninsula for the first time in late 1977. Since, the large, predatory mollusk has been moving north, either displacing or consuming competitors."

In Half Moon Bay on the California Coast, records show that waters have warmed by 1.5 degrees over the last 50 years, and that means a shift in seaweed as well as animals. According to ABC, weedy seaweeds have moved out and more turf-like species similar to what is found farther south along the coast have moved in.

Jaymi Heimbuch

Rising Sea Levels

Tide pools also have to contend with rising sea levels. Tide pools are dependent on the shift of sea level -- most of the species live half their lives out of the water during low tides. However, different species live at different depths of the tide pools, and while it seems subtle, the different depths mean life or death to various species. As climate change causes sea levels to go up, species will have to shift their locations to adapt.

Lori Branham / Flickr / CC BY-NC 2.0

The change in tides signals when various species start eating or start retreating -- which species will be able to make make the shift as rising seas change the depth of their usual habitat is yet to be seen.

Brian Teutsch / Flickr / CC BY 2.0

As the Pacific Institute reports that "sea-level rise will inevitably change the character of the California coast" and not only does that mean humans having to shift farther back from the coastline, but the animals thriving in tide pools will have to adjust as water levels inch their way up the rocks.

Steve Jurvetson / Flickr

Ocean Acidification and Sea Shells

The ocean naturally absorbs carbon dioxide from the atmosphere; however, as humans pump more and more CO2 into the air, more and more CO2 is entering the ocean and it is changing the pH balance of the water. The oceans are becoming more acidic, and that is having a serious effect on animals, especially those with shells.

Ed Bierman / Flickr

Animals such as sea urchins and lobsters have been observed to grow thicker shells when exposed to more acidic waters. While it might seem like good news for the animals at first glance, it's actually not so great. First of all, predators will have a harder time accessing their prey, but the animals themselves are also at risk as they're drained from expending the energy that goes into creating the thicker shells as well as the energy it takes to move around with added weight and bulk.

Steve Jurvetson / Flickr

However, with species such as oysters, clams, and mussels, the acidification causes their shells to dissolve. That means the creatures have weaker armor and will be less able to ward off predators, such as this mussel succumbing to a hungry starfish. And those who depend on others' shells for protection, such as the hermit crab below, will be out of luck.

Anita Ritenour / Flickr

Plus, with different shellfish species reacting differently to more acidic water, the impact could be complex. As a research team from Woods Hole Oceanographic Institute states,"...any possible ramifications are complex. For example, the crab exhibited improved shell-building capacity, and its prey, the clams, showed reduced calcification. 'This may initially suggest that crabs could benefit from this shift in predator-pray dynamics. But without shells, clams may not be able to sustain their populations, and this could ultimately impact crabs in a negative way, as well,' Ries said."

Jaymi Heimbuch

Tide pools are a beloved section of the ocean for humans, providing a menagerie to explore during low tides. However, they're subject to the impacts of climate change just like other fragile ecosystems such as coral reefs.

If you want to explore tide pools before they change too much, be sure to follow tide pool etiquette.