Day 4: Marine Ecology along the Lost Coast

Question of the Day:

Why is the health of the marine ecosystem important to humans?

Character of the Day:

Salmon Species along the Lost Coast. There are three species of fish in the salmon family common in the area: Chinook (salmon), Coho (salmon), and Steelhead (trout). All are anadromous fishes, meaning they migrate between the ocean and freshwater rivers during their lifecycle. All of these species of salmon are listed as "threatened" under the Federal Endangered Species Act, meaning that their population numbers and habitat have decreased dramatically.

Key Concepts:

The Lost Coast marine food web begins with primary producers, a diverse group of microscopic single-celled organisms that convert solar or chemical energy into carbohydrates and other molecules. The vast majority of primary productivity within cold water oceans (e.g., along the Northern California coastline) comes from phytoplankton. Phytoplankton are themselves a diverse group, and include many different classes of organisms including diatoms, cyanobacteria, and dinoflagellates. Phytoplankton thrive in areas of cold water upwelling, a phenomenon where warmer surface water is displaced by wind currents and replaced from below by colder water. Cold water upwelling is common along the Lost Coast. Primary producers provide the base of the food web.

Phytoplankton are consumed by a variety of zooplankton (i.e., small floating animals), including single-celled ciliates, and much larger copepods and shrimp. Larger zooplankton often eat smaller zooplankton. Zooplankton make up the majority of the prey base for the smaller predators, including shrimp, krill, and small fish (e.g., sardines, herring, etc.). The small predators are generally consumed by the larger predators, including squid, octopus, and diving birds (e.g., pelicans, albatross, etc.), marine mammals (e.g., dolphins, seals, walruses, etc.), as well as sharks and other large fish (e.g., tuna, mackerel, etc.). Deceased organisms are broken down into detritus by bacteria and fungi. The Detritus then re-enters the food chain and is consumed by benthic invertebrates and benthic fishes.

Although the complexity and interconnectedness of the marine food web creates a certain level of protection from the normal ups and downs that individual species or groups of organisms may experience, the top and bottom of the food chains are particularly susceptible to these fluctuations. Specifically, declines in phytoplankton production can have a tremendous effect on the larger food web. As the base of the marine food web, declines in phytoplankton can have dramatic effects that cascade throughout the entire ecosystem. Less phytoplankton means less food for zooplankton (which means less zooplankton can survive), less zooplankton means less food for small predators (which means less small predators survive), and so on. Recent increases in oceanic temperatures have seen dramatic declines in phytoplankton levels, a correlation that is worrisome for the health of the marine ecosystem.

Additionally, declines in top predator (tuna and sharks) levels can have serious effects upon ecosystem health. Top predators are also commonly fished for by humans. In recent decades, overfishing by humans has decreased the levels of top predators within many marine environments. Top predators help to regulate the population levels of their prey base. When populations of top predators decline, the proliferation of these prey species can cause similar declines in lower level species. Essentially, without top predators, the mid-level predator populations boom, which in turn over consume their prey species, disrupting the overall ecosystem balance.

Sharks that swim the oceans today are descendants of the living killing machines that have swam before the time of the dinosaurs. Sharks are apex predators in the oceans, perhaps only being threatened by killer whales or human technology. Sharks are found off the Coast of California, drawn there by the vibrant ecosystems supported at the other end of the food chain by nutrient rich deep-ocean currents that upwell along the Coast of North America. What evidence for the presence of sharks in the waters off the shores of the Lost Coast might be observable from land?

Shark trackers

Youth Ambassador Activity:

Observations from shore, should see seals and sea lions, birds of all kinds, maybe a whale or two, kelp, tide pools? Discuss each observed species place and role in the overall food web of the ecosystem. Perhaps collect shells and other things found on the beach discussing how they relate to the ecosystem as a whole.

From the shore, identify the number and types of animal species observable from the shore. Estimate the number of sea lions and seals, then their prey, and so on - how much plankton?

School Activity:

How many great white sharks are resident in the waters off the Lost Coast? Where is the highest concentration of sharks in the world? (answer: South Africa) How much food resource is needed to sustain one great white shark? Need to provide schools with lots of facts, or websites where this information is available.

Daily Dispatch:

How can I visualize something that I cannot see? I can see it, yetI can’t. Keyholes. I will look through its keyholes. I kneel down, and peer through the nearest keyhole. I see !ocks of birds touching down to rest. I move to the next keyhole, and my eyes meet and lock onto a pairs of eyes that stare back to me. What do those eyes belong to, is ita sea otter or a harbor seal? They must have friends, as I see other heads popping just above the surface here and there. I can see intelligence in their eyes, and though I try to talk to them, they just stare back at me. I would ask them what they see when their heads disappear. I want to know what they are thinking. Through the next, I see smooth tapered ropes, bull kelp, tangled on the shore as if they were pushed through another keyhole sometime ago. In another, I seebirds of prey, hawks, !ying high above, and I also see prehistoric-looking birds, pelicans, !irting only centimeters above it, turning to surfin the wind generated by each moving wave of energy. Once, I saw a pelican dive underneath the surface, only to emerge a few seconds later. Why did the pelican dive there? In another, I see harbor seals who have taken a risk. They live in the ocean, yet they have moved onto the beach. Why? They appear so close to the keyhole that I thinkI can reach out and touch them. Wow, they are bigger than me. They are calling out to me, but I do not understand them. Are they saying hello, or help us? What am I really looking at? What if I could open this, and see everything inside? I wonder if the depths of it are endless? What treasures are really in there? I wonder if what I am catching glimpses of through the keyholes will last forever? Is there anything I can do?


(National Oceanic and Atmospheric Admisistration. National Marine Sanctuaries: Cordell Bank Nation Marine Sanctuary. Retireved from: (Texas A& M University. Ocean World: Marine Fisheries Food Web. Retrieved from: (Dolph, Maria. What Happens When the Top Predator is Removed from an Ecosystem? Retrieved from: