The Little Lobster That Reveals Climate

Summary

This episode explores the fascinating world of pelagic red crabs, or tuna crabs, which are not actually true crabs but squat lobsters. Found mostly off Baja California, these creatures' movements are strongly influenced by ocean and climate patterns like upwelling and El Niño events. When caught in strong ocean currents, massive groups of crabs can wash up on California shores, signaling changes in the marine environment. Their increasing strandings point to the broader impacts of climate change, with warmer ocean temperatures and marine heatwaves altering ocean habitats. The Monterey Bay Aquarium highlights the importance of these crabs as indicators of ocean health.

Takeaways

• 😀 Pelagic red crabs, also known as tuna crabs, are actually squat lobsters, not true crabs, and are characterized by their long tails that curl under their bodies.
• 😀 These crabs typically live off the coast of Baja California, where they feed on phytoplankton and other tiny edible marine organisms.
• 😀 While adults live in the benthic zone, the younger stages of the crabs live in the epipelagic zone, the upper part of the open ocean.
• 😀 The movement of pelagic red crabs is influenced by ocean and climate patterns, including ocean currents and upwelling zones that bring nutrient-rich water to the surface.
• 😀 Upwelling areas are important for the crabs' survival because they concentrate the plankton the crabs feed on, and their breeding season aligns with the upwelling periods.
• 😀 Pelagic red crabs are not strong swimmers, especially when young, and can be carried away by strong ocean currents, sometimes washing up on beaches in large numbers.
• 😀 These mass strandings of red crabs are often linked to climate events like El Niño, where warm ocean currents push the crabs northward along the California coast.
• 😀 El Niño events cause more red crabs to wash up on beaches, providing food for predators like seagulls, but also signal disruptions to the ocean's typical temperature patterns.
• 😀 In addition to El Niño, pelagic red crabs also signal marine heatwaves, which can cause ocean temperatures to rise significantly, shifting marine species and affecting ecosystems.
• 😀 The increasing frequency of red crab strandings, especially in recent years, signals changes in ocean conditions, likely linked to global climate change and its impact on marine life.

Q & A

What are pelagic red crabs, and how do they differ from true crabs?

Pelagic red crabs, also known as tuna crabs, are not true crabs but a type of squat lobster. They resemble flattened lobsters with long tails that curl under their bodies.

Why are pelagic red crabs often found on the shores of Monterey Bay?

Pelagic red crabs are typically found on the shores of Monterey Bay when they are swept up by strong ocean currents, particularly during events like El Niño, which cause warm currents to move them from their usual habitats off Baja California.

What do pelagic red crabs eat?

Pelagic red crabs primarily eat phytoplankton, microscopic marine algae suspended in the water, as well as other edible bits they can find.

How are the movements of pelagic red crabs linked to ocean and climate patterns?

The movements of pelagic red crabs are influenced by ocean currents, temperature changes, and upwelling events. They often move with food availability and can be carried away by strong currents, such as during El Niño or marine heatwaves.

What role do upwelling events play in the life of pelagic red crabs?

Upwelling events bring cooler, nutrient-rich water to the surface, which is rich in plankton, providing an ideal environment for pelagic red crabs to thrive. These events also coincide with the crabs' breeding season, ensuring healthier adults.

Why do pelagic red crabs end up stranded on beaches?

Pelagic red crabs can become stranded on beaches when they are carried away by ocean currents, particularly during events like El Niño, when warm currents push them northward from their usual habitat.

How do marine heatwaves affect the distribution of pelagic red crabs?

Marine heatwaves, such as the 'warm-water blob,' have caused pelagic red crabs to shift northward, sometimes reaching areas as far as Newport, Oregon. These heatwaves alter the habitat and food distribution for ocean life.

What is the significance of pelagic red crabs as indicators of climate change?

Pelagic red crabs serve as bellwethers for climate change, as their strandings have become more frequent and are linked to changing ocean conditions such as marine heatwaves, El Niño events, and overall warming oceans.

What was the impact of the warm-water blob on ocean life?

The warm-water blob, which occurred in 2014 and 2016, raised ocean temperatures in the northeast Pacific by 2-4°C for months, leading to the displacement of marine species, harming marine mammals, and triggering harmful algal blooms.

How frequently have pelagic red crabs been recorded stranding on beaches?

Pelagic red crabs have been recorded stranding on beaches since as early as 1859. There were several strandings in the 20th century, and more frequent events occurred between 2015 and 2017, highlighting the growing impacts of climate change.