If Soylent Green is people . . . what is Red Snapper?  Adapted from this news release.

In what is being touted as “the first known student use of the four-year-old DNA barcoding technology in a public marketplace,” Kate Stoeckle, 18, and Louisa Strauss, 17, of New York’s Trinity School sent 60 samples of fish tissue from 14 grocery stores and restaurants in New York City to the University of Guelph’s Biodiversity Institute of Ontario.

There, Dr. Robert Hanner, Campaign Coordinator for the Fish Barcode of Life (FISH-BOL) initiative, and masters student Eugene Wong analyzed the specimens’ “barcodes” — a 652 bp region of their COI gene (mitochondrial cytochrome c oxidase subunit 1).

Red snapper (Lutjanus campechanus) below, red sea bream (used in reference to both Pagrus major and Pagellus bogaraveo) above. It's harder to tell if they're in bite-sized chunks (Consumerist).

Of the 56 samples with identifiable matches in the Barcode of Life Data Systems library, exactly one-fourth were mislabeled — “in all cases as higher-priced or more desirable species.”  Here’s the rundown (ironically, I had to add in the scientific names myself):

. . . In two cases DNA barcode tests revealed that filleted fish sold as the popular Red Snapper [Lutjanus campechanus] (caught mostly off the southeast U.S. and in the Caribbean) was instead the endangered Acadian Redfish [Sebastes fasciatus] (which swims in the North Atlantic).

The DNA of fish from a sushi restaurant, mislabeled “White Tuna” (also known as Albacore tuna [Thunnus alalunga]) matched the barcode for Mozambique Tilapia [Oreochromis mossambicus], commonly raised on fish farms. Farmed, freshwater tilapia sells for a fraction of the price of wild tuna.

A restaurant menu entrée, said to be “Mediterranean Red Mullet,” [generally either Mullus barbatus or Mullus surmuletus] matched the DNA barcode of Spotted Goatfish [Pseudupeneus maculatus], which inhabits the Caribbean.

Seven of nine samples said on packaging to be the popular “Red Snapper” were mislabeled. The DNA of those mislabeled fish matched these species:

· Acadian Redfish [Sebastes fasciatus, critically endangered on the International Union for Conservation of Nature’s Red List]
· Nile Perch [Lates niloticus]
· Lavender Jobfish [Pristipomoides sieboldii]
· Slender Pinjalo [Pinjalo lewisi]

Even bleaker results were obtained by a 2007 expose by the Chicago Sun-Times, which similarly tested “red snapper” from 14 restaurants in the titular city and its suburbs — of which none were actually L. campechanus.

The notion of COI barcodes as “the core of a global bioidentification system for animals” (as his 2003 paper Biological Identifications Through DNA Barcodes puts it) owes a great deal to Guelph professer Paul Hebert.  Fittingly enough, “Identifying Canadian Freshwater Fishes through DNA Barcodes,” a new paper by Hubert and colleagues, became available earlier this summer through PLoS ONE (see here).

According to the press release, Hebert isn’t stopping there:

[Hebert] has also co-authored an upcoming article on using DNA barcodes to reveal the substitution of seafood in North American markets, describing the potential use of barcodes to harmonize across jurisdictions various names for the same fish.

But the champions of marine COI barcoding have hopes far grander than a glorified Peterson’s Guide to Piscine Fauna of Upper Manhattan Fusion Eateries.  The U.S. National Oceanic and Atmospheric Administration, for one, pictures:

· Reliable identification of catch and by-catch on vessels and at the dock;
· Analysis of gut contents to understand food chains in the ocean; and
· Assessment of fish stocks by identifying fish larvae as well as juveniles and
adults.

Yet COI is not without its critics, an issue I’ll leave for another post.

Useful links:

· Barcode of Life Database : www.barcodinglife.org
· Consortium for the Barcode of Life: barcoding.si.edu
· Barcoding marine species: www.marinebarcoding.org
· FishBol: www.fishbol.org
· Barcoding blog: http://phe.rockefeller.edu/barcode/blog
· Ten Reasons for Barcoding Life: http://phe.rockefeller.edu/barcode/docs/TenReasonsBarcoding.pdf

Resources:

Hubert N, Hanner R, Holm E, Mandrak NE, Taylor E, et al. (2008) Identifying Canadian Freshwater Fishes through DNA Barcodes. PLoS ONE 3(6): e2490. doi:10.1371/journal.pone.0002490

Hebert, P.D.N., A. Cywinska, S.L. Ball and J.R. deWaard. 2003. Biological identifications through DNA barcodes. Proc. Roy. Soc. Lond. Ser. B: 270: 313-321.

As I looked further into Procambarus clarkii‘s invasion of the Egyptian Nile, it became increasingly apparent that the CNN article I reviewed in my last post was little more than a jumble of hearsay and poor research.

Wizen et al. (2008), reporting on the first confirmed record of P. clarkii in Israel, look to Egypt as a cautionary tale. The 2005 overview they cite provides a likelier background story (well, no overt talk of prawn-eggs-that-weren’t) and a more definite geographic distribution:

A shrimp farmer in Al Qanater released the imported crayfish into the Nile in the 1980s after they had damaged the mud banks of his ponds. The crayfish have since spread from the Delta to Bani Swaif, 500 km to the south of Cairo, with densities as high as 0.65/m² (El Zein 2005). The crayfish damaged earth dams, irrigation canals and fish stock, and though marketed, are considered of little commercial value. El Zein (2005) admits “such an introduction is now recognized to have bad consequences on biodiversity without economical profits”.

Rosy visions of Zydeco ‘n crawfish festivals on the Nile notwithstanding, the Louisiana mudbug suffers from more than an image problem. Elmossalami and Emara (1999) raise concerns of bacterial contamination — though to what extent they’d be mitigated by common cooking methods remains unknown to me:

The average aerobic plate and Enterobacteriaceae counts/g were 1.6 × 10⁸ and 3.5 × 10⁵, and the coliforms and E. coli were isolated from 100% and 40% of the examined samples respectively. However, Salmonellae could not be isolated from any of the examined samples. 20% of the samples were safe for human consumption, while 33.33% were marginally acceptable and 46.67% were unacceptable.

Interestingly enough, Magdi Tawfik (professor of zoology at Ain Shams University) had in 2003 assured readers of Al-Ahram weekly that consumers had nothing to fear. Name-calling by less sympathetic Cairenes aside (“sea cockroach,” “poisonous insect”), Tawfik gave an approving nod to ecdysis:

Tawfik explained that while the crayfish “clean the Nile water from harmful pollutants, its shell is shed five to six times a year, ridding the crayfish of harmful pollutants. Hence the poisonous material absorbed into the shell does not affect the meat of the crayfish.”

How is Tawfik so sure that pollutants stay sequestered in the exoskeleton, never to befoul organ or muscle tissue? What if you catch an intermolt crayfish and, horror of all horrors, boil it shell and all? Finally, what of P. clarkii‘s customary habit of consuming its molts?

To close, some photos from blogger Khalid Baheyeldin:

Crayfish and crayfish burrow (see left of image) in Bahr Mouweiss, a canal in Zagazig, El Sharqeyya, Egypt.

"Crayfish for sale in El Meidan market in old Alexandria. They are quite cheap, and not much in demand it seems."

Resources:

Baheyeldin, Khalid. “Crayfish introduction to the Nile Delta and its effects.”
Weblog post. The Baheyeldin Dynasty. 22 Mar. 2007 <http://baheyeldin.com/writings/science/crayfish-introduction-to-the-nile-delta-and-its-effects.html>.

Elmossalami, M. K., and M. T. Emara. “Safety and quality of fresh water crayfish Procambarus clarkii in the river Nile.” Nahrung / Food 43.2 (Apr. 1999): 126 – 128. 24 Aug. 2008 <http://www3.interscience.wiley.com/journal/60500951/abstract?CRETRY=1&SRETRY=0>.

El Zein G (2005) Introduction and impact of the crayfish Procambarus clarkii in the Egyptian Nile.
L’Astaciculteur de France 84: 1-12

Mahmoud, Lina. “Not Just Ugly.” Al-Ahram Weekly 9 Oct. 2003. 24 Aug. 2008
<http://weekly.ahram.org.eg/2003/659/fe2.htm>.

Wizen, Gil, et al. “First record of red swamp crayfish, Procambarus clarkii (Girard, 1852) (Crustacea: Decapoda: Cambaridae) in Israel – too late to eradicate?” Aquatic Invasions 3.2 (June 2008): 181-185. 24 Aug. 2008
<http://www.aquaticinvasions.ru/2008/AI_2008_3_2_Wizen_etal.pdf>.

As CNN reports, Procambarus clarkii (the Louisiana or red swamp crayfish) is earning a name for itself as “the cockroach of the Nile.” The article draws effective attention to the perils and, perhaps, unintended windfalls of this alien species’ introduction, but as a piece of scientific reporting it’s pretty shabby. I’ve highlighted some particularly pause-worthy segments below.

A statement from aquatic ecologist Magdy Khalil of Ain Shams University:

“In the 1980’s somebody came to me and said that there was a new creature in the river Nile,” says Khalil. “After two days of examination, we determined it was the fresh water crayfish. It has no natural predator in the Nile.”

Granted, crayfish of any sort are newcomers to the Nile, but I wouldn’t expect its Potamonautid crabs and larger Palaemonid prawns to go wholly unmolested. For what it’s worth, captive Fahaka or Nile puffers (Tetraodon lineatus) take readily to Cajun cuisine:

Estelline, Texas (Wikipedia)

In 1964, one Gordon C. Creel penned the most haunting scientific paper I’ve ever read. Couched in his level-headed taxonomic description is the story of a wondrous, totally singular ecosystem — an ecosystem mangled before his very eyes . . . and today all but forgotten.

It was in 1962, halfway through his biotic survey of the Texas Panhandle and South Plains, that Creel arrived at Estelline Salt Spring in Hall County, Texas. Estelline emerged just east of its namesake town, flowing at around 3,000 gallons per minute into a large pool before emptying into the Prairie Dog Town Fork of the Red River. Creel was meticulous about recording habitat data:

The pool is about 65 feet wide at the surface at an elevation of 1742.5 feet above sea level; it narrows downward and is only 20 feet wide at a depth of 25 feet, but farther down widens slightly to the 120-foot depth. At the bottom of the main pool is an opening about 3 feet wide leading into a large cavity completely filled by water. . . The salinity of the water is nearly constant at 43 ‰, and has a temperature that varies from about 64 to 72° F. The 24-hour oxygen cycle ranges from a low of 2.9 PPM at 6 am. to a high of 4.3 PPM. The pH ranges from a low of 5 to a high of 6.

And the species de novo he described? None other than Hemigrapsus estellinensis.

Fig. 1. Dorsal and ventral view of male (top) and female (bottom) paratypes of Hemigrapsus estellinensis. (Creel, 1962)

That’s right, a crab. In a hypersaline pool, 800 kilometers from the sea — at the eastern brink of the Texas High Plains, for crying out loud — a crab

FIG. 79. Palæmon jamaicensis. A, female; B, fifth thoracic appendage of male. From The Crayfish (Huxley, 1879).

You’ve heard of wolves placental and marsupial, mantises and mantispids — but crayfish and Palæmon?

A few years back, I stumbled across an 1879 work by Thomas H. Huxley (“Darwin’s bulldog”) entitled The Crayfish: An Introduction to the Study of Zoology. This fascinating piece is available in full through the University of Alberta as well as Google Books. In Chapter VI, Huxley introduces us to one of the least-known — and most striking — cases of evolutionary convergence I’m aware of.

Several species of prawns (Palæmon) abound in our own seas. Other marine prawns are found on the coasts of North America, in the Mediterranean, in the South Atlantic and Indian Oceans, and in the Pacific as far south as New Zealand. But species of the same genus (Palæmon) are met with, living altogether in fresh water, in Lake Erie, in the rivers of Florida, in the Ohio, in the rivers of the Gulf of Mexico, of the West India Islands and of eastern South America, as far as southern Brazil, if not further; in those of Chili and those of Costa Rica in western South America; in the Upper Nile, in West Africa, in Natal, in the Islands of Johanna, Mauritius, and Bourbon, in the Ganges, in the Molucca and Philippine Islands, and probably elsewhere.

Many of these fluviatile prawns differ from the marine species not only in their great size (some attaining a foot or more in length), but still more remarkably in the vast development of the fifth pair of thoracic appendages. These are always larger than the slender fourth pair (which answer to the forceps of the crayfishes) ; and, in the males especially, they are very long and strong, and are terminated by great chelæ, not unlike those of the crayfishes. Hence these fluviatile prawns (known in many places by the name of “Cammarons”) are not unfrequently confounded with true crayfishes; though the fact that there are only three pairs of ordinary legs behind the largest, forceps-like pair, is sufficient at once to distinguish them from any of the Astacidæ.

Take a look at today’s species of Palaemon Weber, 1795. None of them bear much resemblance to Huxley’s river-dwelling monsters. What happened?

Palaemon paucidens, an atypical freshwater species from Japan -- no "great chelæ" here!

Well, the genus once served as a catch-all for hundreds of marine, estuarine, and freshwater prawns, but subsequent paring-down has reduced it to 34 species, most of them inhabitants of temperate and tropical coastlines in salt or brackish water (Knowlton et al., 2004). To top things off, some species now included in Palaemon were originally described in the genus Leander E. Desmarest, 1849 (ibid).

So where did Huxley’s “cammarons” go? Most (including the huge species remarked on in the second paragraph) were placed in Macrobrachium Bate, 1868. Another genus, Palaemonetes Heller, 1869, was separated from Palaemon primarily on the basis of morphology — “the absence of a mandibular palp” (ibid).

Palaemonetes vulgaris, a marine species found from Cape Cod to the Gulf of Mexico. Members of this genus, both freshwater and salt, are commonly sold as aquarium feeders under the heading of "ghost" or "glass" shrimp (Mariculture Technology).

Most species of Palaemon tend not to venture very far up rivers, and Lake Erie is stomping ground only for Palaemonetes. Though there is overlap with these other two genera, most of the locales Huxley rattles off refer to the distribution of Macrobrachium (river prawns, long-armed prawns, or — as the Aussies would have it — cherabin). Not all of them are passable crawdad-analogues (these prawns range from tiny burrow-diggers to lanky, stilt-limbed creatures with no real equivalents anywhere else in the animal kingdom) but some do a remarkably good job.

Crayfish: Cherax lorentzi from Papua (Jerry Allen, via Crusta10.de)

Prawn: Macrobrachium carcinus (formerly Palaemon jamaicensis) from Puerto Rico (US Fish and Wildlife Service)

As far as the big chelae go, Huxley is right on the money — count the number of walking legs (pereiopods) following the largest claws. What other differences can you spot?

O, Macrobrachium. Over 200 species strong, inhabiting every continent but Europe and Antarctica, it’s about time that you long-armed beasts make your blogosphere debut.

Resources

Huxley, Thomas Henry. The Crayfish: An Introduction to the Study of Zoology. 1879. Vol. XXVIII. International Scientific Series. New York: D. Appleton and Company, 1880.

Knowlton, R.E. & Vargo, C.K. (2004). The larval morphology of Palaemon floridanus Chace, 1942 (Decapoda, Palaemonidae) compared with other species of Palaemon and Palaemonetes. Crustaceana, Volume 77, Number 6, pp. 683-715(33)

Welcome to Amphidrome!

This blog will play host to a pupil of Nature’s musings on natural history and scientific research. Dipnet and calipers at my side, I’ll be roaming through the wilds of biogeography, aquatic ecology, invasion biology, and systematics. You’ll encounter your fair share of river prawns along the way, but non-carcinologists certainly shouldn’t feel left out. That said — if the locals prove quick to pinch, don’t say you weren’t warned. (Gourmets might be disappointed, but who knows? There’s probably even room for a dastardly shell-peeler or two.)

What’s in store, you ask? Stream-dwellers that waft across oceans, waterfall-scaling filter feeders, foreign mercenaries in a crusade against man-killing snails, and an endless parade of creatures elegant, puzzling, and tragically out of place.

Alex