Archive for November, 2008

November Springs Deathtrap on Turtle Hatchlings

Thursday, November 13th, 2008

Sunny November Lures Terrapin Hatchlings into Deathtrap

In the Great White North we’ve enjoyed a long string of beautiful November weather.  This normally overcast month has been sparked by sunshine and temperatures poking into the upper fifties.  Clear skies allow dunes to bake under the sun, and while humans and seals and other warm blooded-critters savor the unexpected warmth, these unusual conditions lure diamondback terrapin hatchlings to their death.  Twelve babies would have died on Monday if not for the serendipitous intervention of the Turtle Journal team.

Cold-Stunned, Blinded Diamondback Terrapin Hatchling

Sunny November played a cruel trick on hatchlings over-wintering in late nests.  White sandy dunes absorbed days of sunshine, baking terrapin egg chambers buried several inches below ground.  Warm sand coaxed babies out of winter brumation, cuing these tiny hatchlings to tunnel for freedom.  In a normal overcast fall, without a long string of sunny November days, these hatched but unemerged babies would have slept in their nests until the first warm days of May.  Cold-blooded turtles don’t “hibernate” like mammals, sleeping straight through the winter until springtime.  Instead, these reptiles “brumate.”  Although the two processes are similar, the difference can be critical if a bit subtle.  Brumation is triggered by temperature alone and not by season of the year.  A cold snap can drive turtles into summer brumation and a warm stretch in November or December can prompt reptiles to emerge from brumation … while hibernating mammals are snugly snoring away.  For baby hatchlings, that tiny difference can be fatal … as it would have been on November 10th.

Confused Terrapin Hatchling Tracks

The Turtle Journal team had to split up on Monday.  One half attended a board of trustees meeting, and the lucky half got to head into the field to adventure and to look for nature to happen.  Pure serendipity brought Sue (the lucky half) to Sandy Neck in Barnstable for a stroll through the dunes along the salt marsh trail.  An early indication that something was surely amiss was finding hatchling tracks scattered across the dunes in confused patterns that seemed to circle and close on themselves.  First, 10 November is NOT a day when one expects to see ANY terrapin tracks.  But secondly, the confused patterns indicated that these hatchlings were in BIG trouble.

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Cold-Stunned Terrapin Hatchlings Wander Blindly in Circles

Scouting the tracks, Sue soon found her first cold-stunned hatchling, stumbling across the dune, eyes blinded by the cold, wandering in circles.  Once these hatchlings had emerged from their warmed nests, the stinging reality of cold November winds nearly flash froze their dreams of scrambling to freedom in the marsh.  Their body temperatures dropped, they entered a walking stupor, and they were cold to the touch.  Their eyes were closed and their limbs stiff.  They crawled aimlessly until some just froze in place.

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Wobbly, Blinded, Cold-Stunned Hatchlings Near Death

In all, Sue rescued twelve cold-stunned and nearly dead hatchlings.  Unfortunately, she was too late to save two others that had already succumbed to hypothermia.  Luckily, we have had extensive experience dealing with cold-stunned sea turtles and have successfully applied those techniques to their non-migratory marine brethren.  Once out of the debilitating wind, rescued babies began to breath more easily and to relax their frozen muscles.  A few opened their eyes as they rested in secure container for the ride back to the lab at Turtle Journal Headquarters.

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Cold-Stunned Hatchlings Recuperating in Warm Tank

We are always amazed at how resilient terrapins can be.  Given a few hours of gradual, gentle warming and appropriate TLC, baby turtles that seemed within a whisper of death snapped back to playful liveliness.  We understand only too well that these hatchlings may not be able to return to the wild until next spring.  But their return to the salt marsh in May is a superior outcome to becoming crow bait in November.

Maze of Hatchling Tracks Leading Nowhere

One question we needed to assess was whether these cold-stunned hatchlings had newly emerged from a nest or had emerged sometime in the past, but decided to remain buried upland … as we have observed for some subset of hatchlings.  Two key factors decided in favor of newly emerged nests.  First, all the hatchling still sported an extremely sharp egg tooth, suggesting that they had recently pipped.  Secondly, Sue back-tracked most of these hatchlings to emergence holes and nests.

Cold-Stunned Hatchling Collapses after Blind Wandering

November 10th sets a record for diamondback terrapin emergence within our research area.  Yes, we have seen a single hatchling now and then in late fall, but never so many that clearly had emerged directly from their natal nest.  The Turtle Journal team was lucky to be on hand to document the event and to save twelve hatchlings that had been tricked by a cruel November into a certain deathtrap.

Two Giant Ocean Sunfish Wash Up on Cape Cod Beaches

Wednesday, November 12th, 2008

Seagulls Massing in Protected Cove

The weather turned cold today with brisk north-northwesterly winds shuttling heavy autumn clouds over the Cape, ladened with promise of brief winter days and long winter nights.  Birds hunkered in leeward coves to wait out the blow.  Those winds abetted astronomically high tides to drive two large ocean sunfish onto north-facing Cape Cod beaches.  Each measured nearly seven feet in diameter and washed ashore on either side of the Cape Cod Canal: one in Brewster and the other in Bourne.

Students from Ipswich Examine Linnell Landing Ocean Sunfish

We received the first call around noon through the National Marine Life Center in Buzzards Bay when a family spotted a huge, unidentified fish on the Sagamore Beach shore.  Once direct communication was established, the family sent cell phone pictures that confirmed the animal’s identify as a large ocean sunfish.  When we called Krill Carson from the NEBShark Project to report this finding, she told us that she was en route to a reported ocean sunfish stranding at Linnell Landing in Brewster.  Since she was in Middleboro on the mainland side of the canal and we were in Eastham on the Outer Cape, we switched critters.  Krill would check out the Sagamore sunfish and we would examine the Brewster creature.  Light would be fading fast on a mid-November afternoon, and each sunfish needed to be documented before sunset … and before another astronomically high tide might drag it back out to sea.

Large Ocean Sunfish Deposited with Astronomically High Tide

We parked at the Brewster Historical Society and hiked the back trail to the beach.  Directly in front of the beach stairs we found a very large ocean sunfish that had been deposited on the tide.  A group of four boys from the North Shore joined us to learn more about this strange discovery on a bayside beach. 

Large Ocean Sunfish with Its Truncated Caudal (Tail) Fin

The sunfish measured six feet eight inches (curved surface) from tip of snout to trailing edge of caudal fin.  It measured seven feet five inches from the tip of the dorsal (top) fin to the tip of the anal (bottom) fin.  The dorsal fin was two feet four and a half inches high, and the anal fin was two feet three and a half inches low.

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Seven-Foot Sunfish at Linnell Landing, Brewster

Leaving Brewster and the Linnell Landing sunfish, we drove down the main Cape highway, Route 6.  The sun had long set when we reached the Sagamore Bridge and zigzagged through unlit backstreets to Phillips Road along Cape Cod Bay.  We crossed the coastal dune and saw a large shadowy shape illuminated by the dim ocean glow.

Ocean Sunfish on Dark Sagamore Beach

Krill had already inspected this animal and had taken a small tissue sample for analysis.  Just to be sure, though, we took measurements for our own records and for comparision with the Linnell Landing sunfish.

Sue Wieber Nourse Records Ocean Sunfish Measurements

The fun part is trying to take measurements and photographs in the pitch black night.  Luckily, our camera comes with infrared focus … and the hand-held cellphone offers illumination to read tapes and lighted keyboards to enter the data.  The Sagamore Beach sunfish measured six feet eight inches (curved surface) from tip of snout to trailing edge of caudal fin.  The doral fin had been sliced and its top was missing, so our tip of dorsal to tip of anal fin measurement is a bit short at six feet ten inches.  The animal’s girth (curved measurment) reached four feet seven inches.

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Seven-Foot Sunfish at Sagamore Beach, Bourne

For more information about pelagic ocean sunfish, see our post Exotic Ocean Sunfish (Mola mola).

More Torpedo Rays Raise More Questions

Tuesday, November 11th, 2008

The torpedo mystery continues and deepens.  You may have already read in Turtle Journal about the first three torpedo rays that washed up on Cape Cod beaches.  (See Shocking Discovery! Torpedo Ray in Wellfleet Bay and Torpedoes Los!).  Since our last posting, two more torpedo ray deaths have been confirmed: one in Brewster and another in Sandwich.  Both were females, bringing the total to five dead torpedo rays; four confirmed as female, one not examined by the Turtle Journal team.

Cellphone Picture of Female Torpedo Ray in Brewster

On Sunday evening, we received correspondence from Jackie, a Turtle Journal reader from Chatham on the elbow of Cape Cod.  She had encountered an unidentified creature, presumably a skate, on the beach between Ellis and Linnell Landings in Brewster on October 31st.  Jackie estimated the length and the width of the animal to be around three feet.  Realizing that what she found was not a skate, she searched the web to find our postings of the torpedo ray.  While Jackie apologizes for the photo quality (since it came from her cellphone), her images provide excellent documentation of the torpedo ray and its gender identification.  Thank you, Jackie!

Fifth Torpedo Ray to Wash Up on Cape Cod Beaches

Mystery torpedo ray number five drifted ashore in Sandwich.  At noon yesterday (Monday), Vinny from Sandwich … the resident who reported the third torpedo ray last week … called the Turtle Journal 24/7 hotline (508-274-5108).  He found another ray on Carlton Shoals in Sandwich, just a little further to the east than his first discovery.  Luckily, Sue Wieber Nourse was exploring Sandy Neck in neighboring Barnstable and responded to the site to examine the specimen. 

Seagull Munches on Torpedo Ray at Carlton Shores, Sandwich

By the time she arrived, local gulls were licking their chops in delight after munching another tasty seafood morsel.  They had already stipped clean the caudal fin, making length measurements a bit iffy at approximately 3.5 feet.  The width of this torpedo ray across the pectoral fin was two feet three inches.  (You may recall that the other Sandwich torpedo ray measured two feet five inches across its pecs.)  Without Don’s back for a more precise (sic) measurement of the critter’s weight, Sue estimated the weight at around 40 pounds.

Questions still loom about why we are seeing these offshore rays washing up on our inner Cape Cod beaches this fall.  So far, Turtle Journal has no answers to share.

Battle of Shirttail Point — Seals Versus Seagulls

Monday, November 10th, 2008

Town of Wellfleet Seal(s)

Perhaps they do look a bit like Roswell aliens (You know, the grays with big eyes!), but harbor seals appear to have taken permanent winter residence in Wellfleet.  They gulp down fish until their bellies roll, which never takes too long in the rich, oozy waters of the inner harbor.  Then they search for a protected point to bask on soft, moist sand under the brilliant fall sun.  Turtle Journal wonders whether Wellfleet might consider a small adjustment to its town seal to welcome our newest residents.

Seagulls Open Negotiations for Possession of Shirttail Point

Not everyone is happy with the arrival of harbor seals in this Outer Cape hamlet.  Seagulls, who have had no real competition for the riches of Wellfleet Bay and who have had full, free and complete access to every low-tide drained sandbar and point, saw these aliens as unwanted invaders and unfair competitors.  While it’s true that cormorants also effectively hunt underwater for fish in Wellfleet Harbor, they can be rather easily intimidated by a pesky flock of seagulls who steal fish like schoolyard bullies.  Seals don’t suffer the same initimidation.

Negotiations Break Down as Harbor Seal Stands Its Ground

A sated harbor seal hauled out on the tip of Shirttail Point a little after noon.  Soon, a seagull spokesperson arrived to demand that the alien seal give up its position on the point to the native seagulls.  It didn’t take long for the seal to tire of these meddlesome negotations and to break off the talks with a sharp bark.  And so the Battle of Shirttail Point began.

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Battle of Shirttail Point – Seals Versus Seagulls

What the seagulls lacked in size they made up for in numbers, raucous noise and annoying personalities.  Still, the seal held its ground and once reinforcements arrived, the battle turned quickly in favor of the aliens.  If you’re on the Outer Cape during low tide, you may wish to stop by the Wellfleet Pier to get a glimpse of our newest residents.  Remember to give them space.  Marine mammals are protected from human disturbance by federal rules and regulations.

Gourmet Art – Bay Scallops

Saturday, November 8th, 2008

Three Bay Scallops Washed Up on Indian Neck, Wellfleet

As the Turtle Journal team combed the tidal flats of Indian Neck just south of the boat entrance to Wellfleet Harbor, we discovered a large number of bay scallops that had been deposited in the shallows by a previous high tide.  They appeared around, maybe just below, legal harvesting size, and had somehow been dislocated from their deeper locations in Wellfleet Bay between Indian Neck to the east and Great Island to the west.  Seagulls were having a feast, prying open the shells and stripping out the meat.  [ASIDE:  You may have gotten the impression from this and previous posts that seagulls on the Outer Cape enjoy a fairly easy life and a luxuriant palate.  They don’t seem to be bothered by the moral dilemma of shellfish sizing rules.] 

Bay Scallop Opens and Snaps Shut Again

Bay scallops (Pecten irradians) should not be confused with much larger deep sea scallops (Placopecten megallancius) that are harvested off the coast in areas such as Georges Bank.  Bay scallops are sweeter, more tender and much more flavorful.  They are also rare and very difficult to obtain, having been harvested to near exhaustion in pressured coastal habitats.  Today, sea scallops account for the overwhelming bulk of the commercial scallop fisheries and are likely to be the menu item sitting on your plate.  If and when you can order bay scallops, do so.  You will savor the difference.


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Bay Scallop (Pecten irradians)

The shell-clapping behavior illustrated in the video is used by bay scallops to drive jets of water for propulsion to evade predators and to move toward sources of food.  Movement is created by contraction of the yummy adductor muscle.  The process doesn’t quite work as well when being held in mid-air by a human hand, but it gives us an opportunity to examine this artistically exquisite culinary delight.

Two Hinged Shells Held Together by Edible Adductor Muscle

Scallops consist of two hinged shells (hence: bivalve) connected together by an adductor muscle.  This thick white fleshy muscle, the adductor, is the “scallop” that we actually eat; all the rest of the animal is scraped out and tossed back out to sea to re-enter the food chain.  (The entire scallop is actually edible, but U.S. preference is to eat only the adductor muscle.)


Colorful Multihued Shells & Beautiful Blue Eyes

Bay scallop habitat is the subtidal zone in five to twenty-five feet of water.  Scallops spend the first week or so of life as free-floating plankton.  After seven to ten days a juvenile scallop develops byssal threads projecting from its foot and attaches itself to a substrate.  The preferred substrate is eelgrass (Zoestera marina) where juvenile scallops are protected from voracious predators.  They can detach themselves at any time, and after a year or so, the mature scallop breaks free of the eelgrass and settles on sandy and muddy bottoms of harbors and estuaries.  This behavior is unlike their clam relatives such as quahogs and soft-shelled clams that prefer to burrow into sandy, silty bottoms.  Bay scallops reach reproductive maturity around 12 months and will spawn only once in its lifetime.

Coastal development adversely impacts scallop habitat primarily through silt runoff that smothers eelgrass beds.  In estuaries that permit dense boat moorings, such as Sippican Harbor, the constant swinging of boats on mooring lines mows eelgrass beds, while added silting and shading thwart growth of new plants.  Overfishing of bay scallops has been a big problem for sustainable populations, as has the decrease in water quality and clarity, and obviously the drastic reduction in viable eelgrass beds.

“Ol’ Blue Eyes” Himself Would Be Jealous

Scallops are unusual among shellfish in that they frequently rest with their shells open, creating a one-quater inch gap between shells.  Nestled along the mantel are rows of brilliantly colored blue eyes and fleshy tentacles.  Both eyes and tentacles funtion as sensory organs.  Those beautiful blue eyes would have made Frank Sinatra jealous because each animal has 30 to 40 of them.  Scallop eyes are similar to human eyes in that each one contains a lens, a blue iris, a retina & a cornea, and each eye is attached to an optic nerve.  Eyes are sensitive to movement and to shadows, enabling the scallop to detect and thereby to avoid predators.

Blue Eyes along Perimeter; Chemosensory Tentacles Below

Blue scallop eyes are scattered along the outer circumference.  Inside the eyes the mantel is ringed by fleshy, chemosensory protuberances called tentacles that are sensitive to odors and to changes in water temperature.

Chemosensory Tentacles Above; Gills Below

Bay scallops, like other bivalves, are filter feeders and their primary prey are diatoms (phytoplankton).  With its two shells partially open, a scallop can pass large volumes of diatoms across its gills (orange ring below chemosensory tentacles above).  Rows of cilia sweep diatoms across the gill surface, where mucus traps and concentrates diatoms for the palps.  Palps are fleshy tissue on the gills that move diatoms toward the stomach where they are consumed as nutrients and transported throughout the scallop via an open circulatory system.

Edible Adductor Muscle Holds Shells Together

The delicious adductor muscle makes humans the principal predators of bay scallops.  In the plankton stage, scallops are easy prey for fish and other marine animals.  As they grow scallops become prey for crabs and sea birds.  Seastars and oyster drills prey on adult scallops, as do ubiquitous seagulls when they get a chance.  Humans, though, create the greatest impact on scallop populations.  Overfishing has driven bay scallops into extirpation in many estuaries.  Habitat destruction and reduced water quality have exacerbated population declines.

Bay Scallop:  A Gourmet Work of Art

Sue Wieber Nourse led a bay scallop research and restoration project in Sippican Harbor with her Tabor Academy advanced marine science students during the early 2000s.  In collaboration with the Marion shellfish officer, Kevin Snow, Sue and her students spread seed scallops in protective cages in various substrates throughout the bottom of Sippican Harbor.  Besides allowing students to engage in hands-on science with real world impact, Sue’s project increased bay scallop productivity in Sippican for several years.  Unfortunately, the project was discontinued.  You can read about this successful research and education program in a November 2001 article, “Tabor Students Keep Close Watch on Tiny Scallops,” in the New Bedford Standard Times.

Fun Facts:  Life span – 20 to 26 months.  Maximum size in Massachusetts – 3.5 inches.  Reproductively mature in one year; spawns only once in a lifetime.  Spawning time – June 15th to August 15th.  Average number of eggs – 2 million.  Shallow water habitat: prefer 5 to 25 feet depth.  Minimum water coverage at low tide – 1 to 2 feet.