Bioluminescence, Part 2

Bioluminescence is produced by a chemical reaction similar to the one that happens when a glow stick is broken. This reaction releases energy as light. The color of the light that is produced is usually blue or green, but can be red, yellow, or orange, depending on the chemicals used in the reaction. Most animals produce only one color of light, but some fish and worms use two colors of light

Looking for fish beneath cliffs of Laird's Sandstone on Tomales Bay
Photo by Casey Newman, 2011, All Rights Reserved.

Some animals, like fish and shrimp, use photophores, or special organs to produce light. Others, such as jellyfish, have specialized cells scattered over their bodies that glow. Certain species of organisms play host to bioluminescent bacteria, which produce light in exchange for room and board. There are some species of squid that produce bioluminescent ink, which is squirted out as a defense mechanism.  Single celled organisms such as bacteria and dinoflagellates use special compartments in their cell to separate the chemicals that react to produce light, combining the compartments when necessary.

At depths of between 200m and 1000m in the ocean, up to 90% of animals use bioluminescence to blend in with their surroundings. The light that reaches down into those depths is blue-green, and these animals will use bioluminescent photophores (cells or organs that produce light) to match the amount of blue-green light around them, camouflaging themselves.  Other fish that live at those depths produce red light. Many organisms that live that deeply cannot see red light, so the fish that produce it can use the light to see their prey without being seen.  Deeper in the ocean, where conditions are always cold and dark, animals do not need bioluminescence to blend in, but they do use it to attract prey and for communication and courtship. These animals have unique patters of photophores, which may help them to recognize others of their species.

Plainfin Midshipman Fish
Photo copyright Terrence J Fidler, 2006,robots4farms.com

One type of bioluminescent fish, called the plainfin midshipman fish, lives deep in the Pacific Ocean but migrates to the coast in the summer to lay their eggs. These fish are a type of toadfish with no spots or stripes on their dorsal fin. Their photophores are arranged in a U-shape on the underside of their body, and the photophores look like the buttons on a naval officer’s uniform, which is how they get the name midshipman fish. The photophores are used to blend in with the light around them while they are in the ocean, which keeps predators from seeing them from below.

The male midshipman fish returns to Tomales Bay first, digging out a nest in the rocks along the shoreline. The rocks at Nick’s Cove are a favorite spot for these nests. Once there, the males begin to hum to attract females. The hearing of the female midshipman fish is so accurate that they can tell the difference between each male’s hum and find the nest of the hum they like best. Once there, the female will lay her eggs and return to the open ocean. The males fertilize and take care of the eggs, continuing to hum until their nests are full of eggs from many females. The males guard the nest until the eggs hatch and the hatchlings are ready to be on their own.

To hear the plainfin midshipman fish’s hum, visit Discovery of Sound in the Sea: http://www.dosits.org/audio/fishes/plainfinmidshipman/.

Bioluminescence, Part 1

What’s all the fuss about bioluminescence? What IS bioluminescence? 

Sunset over White Gulch on Tomales Bay.
Photo by Casey Newman, 2011, All Rights Reserved. 

It’s the production of light by living organisms. It can be used to attract prey, to communicate, and to help an organism blend in with its surroundings. Bioluminescence is also responsible for the glow that can sometimes be seen on moonless nights in the waters of the ocean. In several places in the world, including our own Bay Area, conditions are perfect for an annual “bloom” of dinoflagellates, a type of single celled organisms that are bioluminescent.

Dinoflagellates are a type of unicellular planktonic organism (whew, what a mouthful). They drift with the currents of the ocean (planktonic), using two whip-like structures (flagella) to move their single-celled selves around a bit. They can photosynthesize, or get energy from sunlight, but some dinoflagellates also eat other, smaller organisms. Most of them have armored plates made of cellulose for a cell wall, which makes them tough for their size (and also beautiful under a microscope). Some dinoflagellate species cause red tides, and release toxins that are harmful to humans. Other species, like the species that is found in Tomales Bay certain times of year, are bioluminescent.

The species of dinoflagellates that bioluminesce operate on a circadian rhythm- they photosynthesize during the day and they only glow at night. Because they only glow when they are jostled, it is theorized that they glow as a defense mechanism. One of their main predators is a type of shrimp, and if they glow when they are about to be eaten, the light will hopefully attract a fish, which will hopefully eat the shrimp. The flash of light may also act as a distraction, blinding the predator to allow the dinoflagellate time to get away.

During certain times of the year, strong winds push the top layer of coastal water offshore, allowing cold, nutrient-rich water to flow up from the ocean floor. This is known as upwelling, and it is responsible for the surge in nutrients that feed an explosion in the population of single celled algae. One species of those algae are the dinoflagellates that produce the light we see on Tomales Bay. Their bioluminescence can occasionally be seen year round, but tends to be strongest in the summer and early fall. The amount of nutrients in the water affects when we can see the bioluminescence and how long it lasts.

The waters of Tomales Bay are a perfect location for viewing the bioluminescence. Tomales Bay has a narrow opening which limits the amount of water that is exchanged during the tides, concentrating the dinoflagelates in the bay. Beds of eelgrass, a plant with long blades, further trap and concentrate the dinoflagellates in the shallow parts of the bay. The northern end of the bay is relatively undeveloped, which keeps light pollution from washing out the flashes of green light when the organisms are moved. 

A paddle through the bioluminescent waters of Tomales Bay is an amazing experience. As we paddle through the water, our boats, paddles, and even hands can jostle the organisms and make them flash. The bioluminescence does not hurt the dinoflagellates, and they can continue to emit flashes of light for hours. On especially dark nights, fish can be seen setting off the bioluminescence as they swim through the waters underneath our boats. The peaceful waters of Tomales Bay provide a protected location filled with wonderful wildlife to paddle past, and the bioluminescence is truly breathtaking.

Sunset on Tomales Bay.
Photo by Casey Newman, 2011, All Rights Reserved. 

Want to know more about bioluminescence? Check out the Bioluminescence Web Page at http://www.lifesci.ucsb.edu/~biolum/, or tune in next week for more information about bioluminescent critters and about a specific type of bioluminescent fish that returns to Tomales Bay every summer.  

East Pacific Red Octopus on Tomales Bay

All Rights Reserved Tressa Bronner

Recently, we had a chance to get out onto Tomales Bay on a beautiful sunny afternoon. It was a great day for paddling as well as viewing wildlife. We saw all kinds of tide pool creatures, harbor seals and seabirds. Our most exciting find, however, occurred as we were launching our kayaks into the bay. Just as the first couple of boats paddled away from the ramp, we began to see long, shiny red tentacles emerging out of the water. Soon after, the head and body of a rather large East Pacific Red Octopus followed as the handsome critter slowly and carefully made his way onto shore. Undoubtedly, our stomping around in the mud launching our boats disturbed him from his cool, shady hangout; but it gave us a great chance to check out one of the bays most interesting bottom dwellers up close as he shifted from red to purple to brown.



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The East Pacific Red Octopus, once thought just be the young of North Pacific Giant Octopus, is its own species entirely. These much smaller cousins of the Giant Octopus only grow to be about 20 inches from the top of their head to the end of their tentacles. Like all octopi, they are capable of changing their color, generally ranging from red to brown and occasionally white. While the Giant Octopus is found in the depths of the ocean, East Pacific Reds prefer the warm shallow waters of bays and estuaries.

Unlike other invertebrates, when the East Pacific Red catches a meal, it does not eat it right on the spot. Instead, it gathers a collection of crabs, clams and scallops and brings them home to enjoy at its leisure. When the meal is done, the octopus carefully stacks the empty shells outside the entrance to their home, giving the other animals roaming the bay a clear idea of who lives there.

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In general, the Octopus is thought to be one of the most intelligent of all invertebrates. Research has shown that they are capable of problem solving and retaining memories. In fact, the East Pacific Red Octopus was the first invertebrate in captivity to show signs of having individual personalities.

Obviously in our rush to get out onto the water we had disturbed the little guy from his normal routine; so once we were finished taking his picture, we helped him find his way into the shade under the dock and out of sight of the hungry seagulls flying overhead.

Glowing Green Halloween 2010

By Joyce Goldfield -Point Reyes Outdoors Customer

Halloween! What on earth does a 73 year old woman do on Halloween? I’m pretty game-I was going to drag out my old pumpkin costume and limp on down to the local happenings in Point Reyes. Just then the phone rang! Saved!



My friend Laurie, who owns Point Reyes Outdoors kayaking, hiking and biking company, spoke. Her question…

“Hey, we have an extra spot on our kayaking trip tonight. We’re going out on the bay to see the bioluminescence. Want to come?”

“Well, yeah!! I was just trying to get up the enthusiasm to don my pumpkin suit and go trick or treating!” My comment received her familiar laugh…

“Great. Meet me at the office at about 4pm and you can ride up with me. We plan to put in at Nick’s Cove in Marshall at 4:30pm. Wear a fleece and some warm socks. I’ve got everything else for you.”

So I did…and she did! She even brought me some extra socks! We rode up to Marshall, followed by her guide, who was driving the van, pulling a trailer of kayaks. The back of the van was stuffed full of gear.

We arrive at Nick’s Cove, just as the late afternoon serenity and softness was settling over the world. Somehow that time of day always inspires me to talk more softly and breathe more deeply.

Kayaks were unloaded and sat bobbing at the water’s edge, waiting. Customers arrived and Laurie greeted them warmly, quickly assessed our clothing and suggested we don one of her waterproof jackets with Velcro closures at the neck and cuffs. She also gave each of us a pair of warm kayaking gloves and waterproof pants. Over the top of all this was a kayaking spray skirt to keep us snug and dry as we paddled. All this was topped with a comfortable life vest. We looked at one another and giggled. I often spend time on the Bay so am accustomed to dressing in layers, but don’t own any of this waterproof gear – and definitely no spray skirt. I’m usually sopping wet halfway across the bay. Not tonight!!

Casey, the guide, gave each of us an individual brush up lesson on how to hold a paddle, advise on strokes, how to operate the rudder pedals (if you are seated in the stern of a two-person kayak) and some wise advice about giving plenty of room to the wildlife, not approaching close enough to flush them from their resting spots. And we were off!!

Tomales Bay Sunset
Photo by Alia Pasquale

Tomales Bay lay flat calm. I’ve lived here for 35 years and have spent many hours sailing and canoeing on this water. I’ve NEVER seen it like this…a shining sheet of glass! Just enough time had passed for the sunset to be at its most breathtaking. Not only was the sky all shades of pink/purple/orange/red, but this palette was reflected across the water, shore to shore. Floating on this amazingly brilliant canvas were all manner of sea bird: loons, cormorants, pelicans, gulls, ducks, herons. The guide knew facts and lore about all of them, which she happily shared. Remember how still and peaceful I told you it was? Now imagine the single call of a loon, floating across the still waters. Cormorants were making noise similar to an “oink”! Then as we approached Hog Island, in the middle of the bay, seals popped their heads up out of the water to view us as we passed. Many were pulled out on the sand spit of the island. Again, so still, we could hear them burp and scratch! Three very young, curious ones followed us. They kept bobbing their heads up to get a better look with their large dark eyes.

Coming around the island, in the middle of the bay, we saw a strange sight. A great Blue Heron was standing ON the water, not wading near shore, but in the middle of the bay. We gave him a wide berth, but perplexed as we tried to figure out his illusion. Floating near us there was a small cluster of bull kelp, a species seldom seen in the bay, but often found in large piles on ocean beaches. These stragglers could have floated in from the ocean, over the sandbar at the mouth, and into the bay. Seems the Heron was standing on a slightly submerged knot of kelp.

The light was slowly fading as we approached White Gulch, on the opposite shore. We cruised in and out of all the nooks, crannies, and caves along the bluff. They pointed out all manner of sea life: Sea anemones gently swaying their fronds to capture food, gorgeous, graceful brown jellyfish pulsing their way along in calm waters, bright star fish and one ethereal white moon jelly. The guide explained that river otters often hang out by the small caves near the bluff.

We paddled toward a small white beach and we pulled ashore. Laurie and the guide pulled out a table and a delightful repast of grapes, chocolate cherry cookies, almond pastries, a three-fruit buckle, and best of all, mugs of steaming hot chocolate.

The night sky was upon us and millions of stars were blooming in the black velvet. Because the water was so calm, every star was reflected therein. Our entire world – sky and water – was a tapestry of golden lights. Behind us, one single elk stood on the hill, silhouetted against the waning light. A huge lone, silent owl flew over us, so low you could feel the rush of the wind from his wings. Having just recently lost my beloved, I smiled, assuming it was his spirit, wishing us well.

Returning to the kayaks, the instant my paddle touched the water, I gasped. I was paddling in molten mercury! In quick silver! I thrust my hand into the water: gloves, jacket and all, wet, just to stir the water with my hand. Everyone was doing the same. We had been conversing in whispers. Not anymore. Everyone was uttering “oohs” and “ahhs” of delight! Then, it got better! EVERYTHING beneath the water was etched in silver and neon green! We could see the sea lettuce and kelp sway beneath. Big, little, wee tiny fish, swimming this way and that…shooting past us, beneath us, in front of us…leading us on their path of silver and brilliant green. Behind us, our wakes were a trail of silver. I scooped up a paddle full of glowing sea lettuce and dropped it back into the water, in a shower of sliver – and laughed aloud.

There was no reason to hurry. We were allowed to wander about (everyone had a red glow stick attached to their kayak for safety). We separated, came together, separated, awestruck!! Where to look? The star strewn black velvet sky? The silver and neon streaked bay, glittering with reflected golden stars? Somehow, it all blended together, it was difficult to see where the horizon line actually was. We were drifting and rotating in a gigantic illuminated bubble. Nobody wanted the evening to end.

As we slowly made our way across Tomales Bay, past the sleep murmurs of the critters on the darkened Hog Island, to the landing at Nick’s Cove…thoroughly relaxed, enchanted, soul satisfied, spirit uplifted, and completely mesmerized by the peace and beauty of it all.

I think I can safely say, that none of us will ever forget this evening as long as we live. None of us will be swept up in life to the extent that this evening doesn’t still dance behind our eyes…in our souls.

Leopard Sharks in Tomales Bay and Drakes Estero

Leopard Shark. Photo by Kambiz Kamrani. 2005

The easily identified Leopard Shark is often encountered in our waters near Point Reyes, often when paddling near them in our kayaks on tomales Bay and Drakes Estero. But it is in the turbid estuarine environment where this attractive little hunter really shines. Paddling around in June and July we often see the water roiling about with tails and fins as these beautiful fish find mates and give birth.

Leopard Sharks do not rule these murky waters uncontested. They share estuaries with, among other, Shovelnose Guitarfish, Bat Rays, and the Brown Smoothhound Shark. The Leopard Shark and Brown Smoothhound are closely related and would be expected to be competing for the same resources. A study looking at the feeding habits of the Leopard Shark and the Brown Smoothhound in San Francisco Bay found that both species feed predominantly on shrimps, crabs, and fishes, but that Brown Smoothhounds hunt predominantly in rocky intertidal areas while the Leopard Shark tends to feed more in muddy areas of estuarine waters.

Leopard Shark at Point Dume. Photo by Heal the Bay. 2008

Leopard Sharks have a richly varied diet and employ several predatory tricks to secure their meals. Some Leopard Sharks feed heavily on Fat Inn-Keeper Worms, which are forcefully sucked from their U-shaped burrows. Others mutilate burrowing clams by nipping off their fleshy siphons (breathing tubes which stick out of the mud), completely ignoring the rest of the critter. When feeding on circling, densely packed schools of anchovies, Leopard Sharks have been reported to circle in the opposite direction with their jaws open, snatching up the small fish that crash right into their mouths. Their adaptable feeding behavior and appetite for several different species, undoubtedly contribute to their success.

"Jaws" Leopard Shark. Photo by Kambiz Kamrani. 2005

The Facts:

Size: At birth, Leopard Sharks are 7-8 inches. At maturity males are 28-47 inches, females are larger, 43-51 inches. The maximum recorded length is 71 inches.

Reproduction: Males mature at 7years, females at 10 years. They are ovoviviparous, meaning that they give birth to live young that have hatched from eggs within the body. The gestation period is around 12 months, at which point they give birth to 4-30 pups alternate years.

Diet: Juveniles mainly eat shore crabs. While adults have learned a scattered diet of small fish, rock crab, worms, clam siphons, and fish eggs.

Habitat: Leopard sharks are found in and around estuaries, sand bars, rocky reefs, kelp forests and especially like pliable muddy bottoms where food can be found and pried out easily.

Depth: Intertidal, literally inches deep, to about 300 feet.

Bat Rays in Drakes Estero and Tomales Bay

Bat Ray. Photo by Linda Thomas. 2005

Bat rays are commonly seen in our shallow waters of Tomales Bay and Drakes Estero. Kayaking along, often you will see the tips of their grayish-brown fins flapping just above the surface of the water as they meander through the eelgrass beds. The Bat Rays we find in Tomales Bay are a type of Eagle Ray and you may have heard someone refer to a “bat ray” as an “eagle ray”. Bat rays are sometimes sought after by fisherman for there edible meat. In some areas around the world rays have been overharvested and beaches filled with their remains lie as a daunting reminder to any species fragility.

 Ray Skeletons, Baja California Sur, Mexico. Photo by Tressa Bronner. 2007

Bat rays were eating oysters being farmed in the bay for human consumption, but they weren't the only marine animal looking for a meal.  There was a push by farmers to reduce the predation of their farmed oysters by the rays. With the reduction of bat rays and continued predation of their oysters it was discovered that the rays were actually feeding on crabs that were feeding on their oysters. 

These creatures are fun to watch and it is magical when they swim underneath your kayak.

Kayaking Drakes Estero. Photo by Tressa Bronner. 2009

The Facts:

Size: At birth, these rays are around 8 inches across and are born with their tail wrapped around themselves to protect the mother from the barb on their tail while giving birth. Rays grow steadily until hitting maturity, at which time growing slows. Females are larger than males, ranging 40-70 inches across at maturity. Males range from 23-40 inches across at maturity.

Diet: Bat Rays use ther "wings" to hunt for food. Flapping their pectoral fins in the sand, they expose buried prey, such as clams. Rays also use their lobelike snouts to dig prey from sandy bottoms.

Bat Ray Photo by Linda Thomas. 2005

Reproduction: Males typically live up to six years. Females live longer, up to 25 years of age. In May-July, 2-10 pups are live born after a ten to twelve month gestation period. During mating season, June and July, the rays can be seen in Drakes Estero and near the oyster beds north of Hog Island in Tomales Bay. The rays move into the estero for birthing just as the harbor seals are wrapping up their birthing season.

Range: Bat rays move into open coastal waters as water temperatures drop below 50 degrees F and head for warmer water. They are often seen schooling with smoothhound sharks and leopard sharks as they travel.

Predators: Bat rays are eaten by Great White Sharks, Seven gill sharks, and occasionally by sea lions and humans.

Stay tuned for our next blog about creatures we have been seeing while on the water, leopard sharks.

*Linda Thomas has more photos available for viewing . Check out her ac4it's Flickr page.

Eelgrass in Tomales Bay

Kayaking on Tomales Bay, near shore and in shallow water, we see long green strands that look a lot like seaweed, but actually, it is eelgrass. Eelgrass moved into the marine environment from land around 65 million years ago. It's actually a flowering plant, one of only two in the oceans.

Embarking on an Eelgrass Adventure, Tomales Bay.
Photo by Joseph Kinyon 2009. All rights reserved.

As the days grow longer, and the water warms, millions of pieces of pollen are released and fertilization takes place. In August these plants will then release hundreds of tiny seeds that will sink to the muddy bottom or be carried away by the current. Eelgrass beds have been the subject of interest for awhile, and scientists have some very cool findings. This plant helps to stabilize the coastal zone. Because their leaves are close together and often interwoven by the tides, they actually reduce the motion of the water. As the water slows, suspended material carried around by the tide and current, sinks to the bottom. The important supply of detritus that the eelgrass beds provide for near shore and off shore systems creates areas 10-100 times richer in animal life      compared to adjacent habitats.

In September, the leaves break away from the roots. Some float away, carried by currents; others fall to the bottom where a large percentage of the leaves decompose. Microscopic organisms begin to break down the leaves into smaller particles, and these become surrounded by bacteria and fungi. Bacteria and fungi are consumed by filter feeders such as clams and scallops. Deposit feeders (such as sea urchins) and sediment feeders (worms and snails) also join in to feast. The adult and larval forms of these invertebrates become food for larger life forms such as fish. The closely packed leaves provide a safe haven for young fish to try to avoid predation, the dense jungle of leaves often deters larger fish from going in too far. Thus the continuous cycle that eelgrass plays such a vital role is illuminated.

Eelgrass is difficult to eat for many birds because it is extremely fibrous. However, Brandts Geese rely on eelgrass to survive their 3000 mile migration. They have a specialized crop to ease digestion. Surf Scoters and Scaups swim down and clip off pieces of eelgrass in order to eat the herring eggs that are developing on the blades.

Dendronotus Iris Nudibranch. Photo by Joseph Kinyon 2009.
All rights reserved.

Waterfowl are often easy to spot, but what they are looking for in the eelgrass often eludes us, unless we look carefully. Hiding within the jungle of blades one can find: herring eggs, nudibranch (sea slugs) and their eggs, copepods & isopods (small crustaceans), polychates (marine worms), clams, bryozoans, and varying forms of bacteria and fungus. At least 20 species of commercially valuable fish rely on eelgrass for food and habitat at some point in their lives. Searching for food in the rich, muddy areas surrounding the beds we often see leopard shark, bat rays, and other large predatory fish.

As we learn more and more about eelgrass, we also learn that eelgrass is helping to mitigate the impacts of humans on our waterways. Eelgrass is crucial to maintaining water quality. 1 acre of eelgrass absorbs 6.4 pounds of nutrients. This is equal to the effluent from 490 people for 1 year. Eelgrass plays a significant role in moderating the effects of increased carbon dioxide on our planet. 1 acre of eelgrass removes 7400 pounds of carbon. This is equal to the carbon dioxide emitted from a car traveling 3860 miles. Eelgrass beds are very difficult to restore once they have been destroyed (by pollutants, boat propellers and anchors, dredging and development). Less than 10% of restoration attempts are successful after 10 years.

Splendor in the Eelgrass, Taylor's Sea Hare. Photo by Joseph Kinyon 2009.
All rights reserved.

Next time you are out on the water, tread lightly in eelgrass zones and be sure to take a closer look at the eelgrass beneath your boat. For a special treat, check out the eelgrass beds after dark. Bring a headlight and be prepared to get wowed by all of the creatures.

Want more: Check out Joseph Kinyon’s article Splendor in the Grass, on Bay pipefish, an eelgrass resident with some extraordinary adaptations for its environment.
Photos provided by Joseph Kinyon. All rights reserved. To contact Joseph or to see more of his photos, Find his "palustrine" Flickr  page.

April Showers, Flowers, and Sunshine

Springtime in Point Reyes is keeping the hills green. Beautiful weather followed by showers have kept the grounds lush and provided swells of wildflowers.  The peninsula is covered with colors as new flowers pop up daily. Checkerbloom, lupine, iris, poppies, blue eyed grass, and pussy ears color the green hillsides.

             

Walk out to Kehoe beach in a sea of mustard's brilliant yellow, or walk out to Chimney rock to a kaleidoscope rainbow of color dotting the path.  Gray whales are still being seen on their northward migration. A few lingering elephant seals are starting their molt.  Kayaking on Tomales Bay has been phenomenal, as the bay is teaming with wildlife. Harbor seals and their pups can be seen on Hog Island and swimming in the bay. Rafts of migratory waterfowl are foraging and resting, some here just for a break before continuing on, others stopping for the summer.

Plenty to see and do, the question right now is rain or shine? Bring your rain coat and your sunscreen and have a great time.Call us today to plan your next great adventure. Point Reyes Outdoors 415.663.8192

Game on...

As we gathered at Miller Park for a midweek paddle, the winds were present, maybe 5 mph. We paddled across toward Hog Island and were delighted to see harbor seals and their pups hauled out on shore. As we slowly floated by, their big eyes followed our brightly colored kayaks. As we entered White Gulch, the winds began to die down and our float through the gulch resulted in leopard shark and jellyfish sightings. Just before lunch we unsealed our skirts and played a round of kayak basketball. It was a close game but it got called short as our hungry bodies demanded fuel. The protected beach allowed us to dry out a bit as we enjoyed our lunch and conversation. The bay was flat as we reentered our kayaks and returned towards the launch. The harbor seals again watched us float by and a couple followed us, alerting us to their presence as they came up for air with a slight exhale.

For more information on our tours visit our website:

www.pointreyesoutdoors.com