Pacific Rocky Intertidal Monitoring: Trends and Synthesis
Southeast Alaska is a coastal temperate rainforest called the Alaskan Panhandle and is wedged between British Columbia and the Gulf of Alaska. Canada lies to the south, east and north with the landmass consisting of a narrow stretch of mountainous mainland and over a thousand islands of various sizes collectively known as the Alexander Archipelago. These islands, spanning 300 miles, are steep sided, densely forested, and receive hundreds of inches of rain annually.
This high volume of freshwater transports nutrients and sediments from the forest to the ocean creating a rich, productive marine environment. Mixing occurs as a result of strong currents, high winds from winter storms, and large tidal ranges. Southeast Alaska connects the marine environments of British Columbia to the waters of the northern Gulf of Alaska, likely maintaining a biological integrity within these marine ecosystems.
The inside islands and waterways, called the Inside Passage, are separated by deep channels and fjords and are relatively protected from large waves. The western shorelines of the islands located along the exposed outer coast are directly adjacent to the Gulf of Alaska. This area receives tremendous wave action along the rugged, rocky coastline. The water is constantly agitated; weather is uniform; seldom varying from cool, wet, foggy and windy. Animals living anywhere in the intertidal are exposed to spray and surf, hence the distribution animals based on zonation is less defined along the exposed outer shores, compared to the inside waters where there is less wave action.
In 1932, a team led by Ed Ricketts and Jack Calvin explored and collected specimens along the Inside Passage and ended in Sitka, on the wave-swept shores of the outer coast in Sitka Sound. These surveys were included in Between Pacific Tides, a seminal volume on intertidal biology and the relationship of the animals within a tidepool. Sitka was the home of Calvin who had moved there a few years earlier from the Monterey Bay area where he was a colleague of Ricketts. Here they found Sitka Sound an ideal location to compare wave action impacts on different habitats within the intertidal. Three sites were surveyed within the waters of Sitka Sound by the Ricketts and Calvin team. In 2012, two of these sites were reestablished using the Biodiversity Survey Protocol: Pirates Cove and Kayak Island. We also re-established a monitoring site on Sage Rock adjacent to the Sitka Sound Science Center, first sampled by Dr. Molly Ahlgren in 1995.
Sitka is a commercial fishing village and many residents make their living from the sea and depend on marine resources for subsistence including traditional hunting and gathering. Although the area remains largely untouched by development the area is at risk from oil spills, invasive species, and natural destructive events such as tsunamis. The Gulf of Alaska is also being impacted by climate change and changes in ocean acidification. Monitoring of key sites in Sitka Sound is important to document changes in the ecosystem through time and intertidal communities provide a good indicator of change.
Biodiversity surveys have been done in this region since 2003, and Long-Term Monitoring sites were established in 2011.
The Pacific Rocky Intertidal Monitoring sites located within Southeast Alaska are listed below (arranged north to south):