Wednesday, May 25, 2016

Appalachia Darter: An Endemic Black-Blotched Darter of the New River, by Don Orth

The Appalachia Darter Percina gymnocephala is one of the rare, endemic darters of the New River.  It does not have any special state or federal status.   Darters are most derived members of the family Percidae, and their reduced or absent swimbladders and enlarged pectoral fins make them superbly adapted for benthic life. Percina is the second largest genus of the darters with 46 species.  Because members of the Percina genus are larger, with drab colors, and high meristic counts, Percina has more plesiomorphic traits than the more colorful and speciose Etheostoma (156 species).  The darters (Etheostomatinae) contains 250 species endemic to eastern North America.  

The Appalachia Darter has traditionally been classified in the subgenus Alvordius, which is the largest subgenus of Percina with 14 species.   Alvordius might be named the “black-blotched” darters in recognition of the 6 to 16 lateral black blotches that these fish all possess.  All members of this subgenus have a large terminal mouth, lateral blotches, dorsal saddles, and a broad frenum.      
F points to frenum on a darter. Illustration from Jenkins and Burkhead (1994).
The Appalachia Darter has 6-8 (sometimes 9) lateral blotches.  The blotches are may be oval, square, or rectangular, and are interconnected.  They have dorsal saddles that are sometimes interconnected to form chain-like pattern.  There is no pigmentation below the lateral band and the lateral band extends to the opercle and snout. The snout is moderately rounded and the mouth is terminal.  Appalachia Darters possess a teardrop-shaped dark spot below each eye.   Fins are mostly transparent with scattered melanophores.  There is a proximal dark band on the first dorsal fin.    
Appalachian Darter Percina gymnocephala holotype specimen from Beckham (1980)
Appalachian Darter Percina gymnocephala  photo from Jenkins and Burkhead (1994).

Early investigators recorded the presence of Appalachia Darter to be the more widespread Blackside Darter Percina maculata.   However, it was elevated to a new species after further examination of specimens by Eugene Beckham (1980).   It’s closest relatives are likely the Shield Darter Percina peltata and the Piedmont Darter Percina crassa, based on external characteristics.  In photos (below) you can observe the many similarities and differences among these darters. Much about the phylogeny of the Percina is yet to be fully explained (Near 2002; Near et al. 2011).   Several Alvordius species do not group strongly with any other Percina lineages, suggesting that presumed monophyly was inappropriate. Phylogeny is likely much more complicated that we can currently imagine.

There are many similar looking "black-blotched" darters that you may encounter; there are slight differences that may require a magnifying lens. Admittedly, the most efficient way to distinguish some of these "black-blotched" darters is to ask what drainage they are from. Many of these species do not overlap with the Appalachia Darter.   The Shield Darter Percina peltata is very similar but  has a large Atlantic slope distribution from the Hudson and Susquehanna rivers south to the James River.  The Shield Darter has rectangular or square lateral blotches that are not interconnected.

Shield Darter Percina peltata  Photo by J. Abatemarco, NJ DEP.
The Blackside Darter Percina maculata is also very similar.  It has a distinctive spot at the base of the caudal fin and possesses scales on the opercle and cheek, while the Appalachia Darter lacks all these traits. It also has a dark blotch on the front lower portion of the first dorsal finAppalachia Darter has only 1-5 scales along dorsal margin of opercle.
Blackside Darter Percina maculata Photo by Uland Thomas
Piedmont darter Percina crassa is from the Cape Fear, Pee Dee, and Santee drainages and does not overlap with the Appalachia Darter.   Otherwise it is very similar and distinguishing traits are larger scales (you have to count lateral line scales).
Piedmont Darter Percina crassa   Photo Scott Smith,
The Stripeback Darter Percina notogramma resembles the Appalachia Darter but is distributed in the Atlantic slope streams from the Patuxent in Maryland to the James River of Virginia.  

Stripeback Darter Percina notogramma. Photo from Jenkins and Burkhead (1994)
The Longhead Darter Percina macrocephala is another Appalachia Darter lookalike.  Note that the lateral blotches are more confluent with each other creating a lateral band pattern and the upper body lackwsdistinct saddles. 
Longhead Darter Percina macrocephala  Photo by Ohio DNR
The Dusky Darter Percina sciera has no teardrop under the eye.  Also, it has an irregularly shaped blotch on the caudal base that appears to be formed from three fused pigment spots. 

Dusky Darter Percina sciera Photo by Uland Thomas
The Roanoke Darter Percina roanoka is the one black-blotched darter that also occurs in the New River and may overlap some with the Appalachia Darter. The snout of the Roanoke Darter is blunter than the Appalachian Darter.  The blotches of the Roanoke Darter are more vertically elongated and there two bands of pigment (one orange, one black) in the first dorsal fin.  Roanoke Darter is the most colorful of these black-blotched darters.
Roanoke Darter, Percina roanoka. Photo by Uland Thomas
I sampled the Federally Threatened Leopard Darter Percina pantherina in southeastern Oklahoma streams many years ago (Jones et al. 1984).  It too resembles these black-blotched darters but the blotches are disconnected and the combination of blotches and saddles form "leopard" spots.  

Leopard Darter Percina pantherina  Photo by Daniel Fenner.
The Appalachia Darter are not common at the locations where they do exist.  Steven Chipps and associates (1994, while studying habitats of other darters, described habitats used by the Appalachia Darter.  Appalachia Darters were usually found in runs and shallow pools with cobble substrate.  They were observed swimming above the streambed, a trait referred to as hyperbenthic. Depths averaged 44-55cm and current velocity has 11-13 cm/s.  The associated Candy Darter Etheostoma osburni and Fantail Darter Etheostoma flabellare were in shallow and faster riffle habitats.  With such habitat affinities, the Appalachia Darter would be easy prey for large bodied sunfish, Rock Bass, and Smallmouth Bass in larger streams.   

Appalachia Darters were rarely encountered in samples from the mainstem New River in West Virginia (Easton et al. 1994) but appear to be more associated with stream reaches in the Blue Ridge province (Jenkins and Burkhead 1994).   Based on collection records summarized by Beckham (1980), the Appalachia Darter occupies cool and warm rivers with an upland gradient
Distribution of captures of Percina gymnocephala from Beckham (1980). 
Recently Jian Huang and others (2016) developed a species distribution model to predict probability of occurrence for several New River fishes.  The map below color codes the stream segments according to likelihood that the segment will support the Appalachia Darter.  However, we need to sample more segments in order to better define the factors that drive the distribution and abundance of the Appalachian Darter. 
Predicted species occurrence of Percina gymnocephala from Frimpong et al. (2014).
Beckham, E.C. 1983. Systematics and redescription of the blackside darter, Percina maculata (Girard), (Pisces:Percidae). Occasional Papers of the Museum of Zoology, Louisiana State University 62.
Beckham, E.C. 1980. Percina gymnocephala, a new percid fish of the subgenus Alvordius from the New River in North Carolina, Virginia and West Virginia.  Occasional Papers of the Museum of Zoology, Louisiana State University 57.
Chipps, S.R., W.B. Perry, and S.A. Perry.  1994.  Patterns of microhabitat use among four species of darters in three Appalachian streams.  The American Midland Naturalist 131:175-180.
Easton, R. S., and D. J. Orth.  1994. Fishes of the main channel New River,West Virginia. Virginia Journal of Science 45:265-277.
Frimpong, E.A., J. Huang, and Y. Liang.  2014.   Preliminary Application of a framework for modeling habitat suitability and distribution of stream fishes with field testing.  Final Report submitted to U.S. Geological Survey. Reston, Virginia.  24 pp.
Huang, J., E.A. Frimpong, and D.J. Orth. 2016. Temporal transferability of stream fish distribution models: can uncalibrated SDMs predict distribution shifts over time? Diversity and Distributions 1-12.  DOI: 10.1111/ddi.12430
Jenkins, R.E., and N.M. Burkhead.  1994.  Freshwater fishes of Virginia.  American Fisheries Society, Bethesda, Maryland.  1037pp.
Jones, R.N., D.J. Orth, and O.E. Maughan. 1984.  Abundance and preferred habitt of the leopard darter, Percina pantherina, in Glover Creek, Oklahoma.  Copeia 1984:378-384
Near, T.J. 2002.  Phylogenetic relationships of Percina (Percidae: Etheostomatinae). Copeia 2002(1):1-14.
Near, T.J., C.M. Bossu, G.S. Bradburd, R.L Carlson, R.C. Harrington, PR. Hollingsworth, Jr., B.P. Keck, and D.A. Etnier.  2011.  Phylogeny and temporal diversification of darters (Percidae: Etheostomatinae).  Systematic Biology 60(5):565-595.  doi: 10.1093/sysbio/syr05

Sunday, May 22, 2016

Finding Sustainability in the Marine Aquarium Trade, by Don Orth

Most marine fish in  aquarium stores come directly from the wild, unlike the freshwater aquarium trade. We want to believe the marine fish in pet stores were bred in marine ornamental fish farms, but that is not the reality. Rather, 90% of the marine fish are harvested directly from coral reef environments.  U.S. imports millions of aquarium fish and invertebrate specimens, comprising thousands of species, to support its marine aquarium industry. One study estimated that 11 million marine ornamental fish entered the US in one year (Rhyne et al. 2012).  Among the most popular are Anemonefishes and Damselfishes (family Pomacentridae).  Harvesting these fish from the wild may cause a host of problems because of ineffective management schemes to protect these fishes and associated coral reefs.   Consequently, the global marine aquarium trade industry is not sustainable under current practices.  
Chromis viridis Blue-Green Chromis, one of the most popular marine fish imported to the US. Source
Harvesters often target juvenile fishes from many species and stock assessments are difficult and costly, so status of the harvested populations is often unknown. Cyanide is often used to easily capture numerous individuals. Fish react quickly to cyanide but will recover if transferred to clean seawater.  However, cyanide use damages coral reefs and is risky to the harvesters.   Release of nonindigenous species is another risk associated with marine aquarium trade.  In Florida, over 30 nonindigenous species of marine fish have been released (Schofield et al. 2009).  The best-known example is the lionfish,  (Pterois spp.) which has rapidly expanded from Florida throughout the Bahamas. 

Because harvest practices are often poorly regulated, it is difficult to estimate the total take of marine fish for live export in the aquarium trade. The length and complexity of the supply chain, along with poor harvesting, handling, and holding practices increase mortality (Cohen et al. 2013).  Some studies indicate that as many as 80% of marine fish die during capture, shipment, or handling.  In addition, many fish harvested will never reach the market because of quality issues and rejection by buyers. Reputable and sustainable marine products should follow standards established by the Marine Aquarium Council, in order to be certified and have eco-labels. Yet, eco-labeling is not common practice in the industry.   Net-captured marine tropical fish often receive premium prices by certain buyers.
Yellow Tang Zebrasoma flavescens is one of the most popular marine aquarium fishes. Photo by Fred Hsu
Coral reef ecosystems are among the most threatened on the planet.  Pollution and climate change impair the health of these vital ecosystems.  Unregulated take and damaging fishing practices simply depress ecosystem values even further.  The most critical and diverse region is called the Coral Triangle, waters off Indonesia, Malaysia, Papua New Guinea, Philippines, and the Solomon Islands.  Many initiatives and organizations are involved to improve the sustainability of the marine trade industry.  One important source is Hawaii, where 30% of exported fish (150,000 fish per year) were Yellow Tang Zebrasoma flavescens (Lecchini et al. 2006).   Hawaii has recently established a network of areas closed to aquarium fishing, on the prime-target species, Yellow Tang.  Only licensed collectors are permitted to harvest yellow tangs in Hawaii.  The Yellow Tang is a very long-lived fish (> 40 years) that has benefited from these protected areas.    
Nemo, is a clownfish from the movie Saving Nemo
Nemo, a talking clownfish, from the movie Saving Nemo familiarized many young children with the clownfish.  Fortunately, the clownfish is among the simplest marine fish to raise in captivity.  Two Australian universities founded the Saving Nemo Conservation Fund to support breeding clownfish to ensure populations are not harvested from the wild.  Dory is the popular talking Blue Tang fish in Saving Nemo and Finding Dory; her voice is Ellen DeGeneres.  Release of this new movie in June may result in renewed pressure to harvest Blue Tang, a fish that cannot yet be bred in fish nurseries.  Consequently, a social media campaign, using #fishkiss4nemo, is underway to promote sustainable practices for marine aquarium trade.   

The National Marine Fisheries Service, U.S. Customs and Border Protection, and U.S. Fish and Wildlife Service could use the Lacey Act authority to more effectively crack down on cyanide-caught fish by requiring testing and certification of imported tropical fish (Colado et al. 2014). Alternatively, marine fish buyers can use the Tank Watch app to select fish to buy after learning which saltwater aquarium fish species may be captive-bred and which are captured in the wild.   You can also support organizations, such as For The Fishes, that support sustainable aquarium trade and health oceans.  Celebrate and promote activities of World Oceans Day which is June 8. Follow @celebrateoceansday #worldoceansday @savingnemo for more stories.  There are numerous public aquariums worldwide that promote marine conservation and source and display marine fish in sustainable ways.  
Lemon Damsel Fish Pomacentrus moluccensis. Photo by Louise Murray
Virginia Tech (Virginia Seafood Agricultural Research Center) launched a conservation aquaculture effort to tank raise popular marine aquarium fishes. This effort provides practical knowledge and a potential opportunity for American businesses to raise and sell the fish instead.  Research on captive breeding of marine ornamentals is still in its infancy, but someday may serve to reduce the demand on the thousands of marine species (Moorehead and Zeng 2010).

Calado, R., M.C. Leal, M.C.M. Vaz, C. Brown, R. Rosa, T.C. Stevenson, C.H. Cooper, B.N. Tissot, Y-W. Li, and D.J. Thornhill.  2014.  Caught in the act: how the U.S. Lacey Act can hamper the fight against cyanide fishing in tropical coral reefs.  Conservation Letters 7(6):561-564. doi: 10.1111/conl.12088
Cohen, F.P.A., W.C. Vaenti, and R. Calado. 2013. Traceability issues in the trade of marine ornamental species. Reviews in Fisheries Science 21(2):98-111. DOI: 10.1080/10641262.2012.760522
Lecchini, D., S. Polti, Y. Nakamura, P. MOsconi, M. Tsuchiya, G. Remoissenet, and S. Planes. 2006.  New perspectives on aquarium fish trade.  Fisheries Science 72:40-47.
Moorhead, J.A., and C. Zeng.  2010. Development of captive breeding techniques for marine ornamental fish: A review. Reviews in Fisheries Science 18(4): 315-343, DOI: 10.1080/10641262.2010.516035
Rhyne, A.L., M.F. Tlusty, P.J. Schofield, L. Kaufman, J.A. Morris, Jr., and A.W. Bruckner.  2012. Revealing the Appetite of the Marine Aquarium Fish Trade: The Volume and Biodiversity of Fish Imported into the United States.  PLoS ONE 7(5):  e35808. doi:10.1371/journal.pone.0035808
Schofield, P.J., J. Morris, and L. Akins. 2009. Field guideto nonindigenous marine fishes of Florida. NOAA Technical Memorandum NOS NCCOS, Silver Spring, Maryland. 92 p.
Williams, I.D., W.J. Walsh, J.T. Claisse, B.N. Tissot, and K.A. Stamoulis. 2009. Impacts of a Hawaiian marine protected area network on the abundance and fishery sustainability of the yellow tang, Zebrasoma flavescens. Biological Conservation 142: 1066–1073.  doi:10.1016/j.biocon.2008.12.029

Wednesday, May 18, 2016

Perplexed about the Endemic Chub of the New River? Blame it on the Pleistocene, by Don Orth

The Bigmouth Chub is one of eight endemic fishes in the New River.  It is a special fish in a special place.  Bigmouth Chub is a member of the genus, Nocomis, which was first described in 1856 by Charles Frédéric Girard, a student of Louis Agassiz. However, it wasn’t until 1971 that the Bigmouth Chub was described as Nocomis platyrhynchus.   By that time the distributions of other Nocomis were well described and the Bigmouth Chub had this difficult-to-explain allopatric distribution with its closest relatives, the River Chub Nocomis micropogon and the Bull Chub Nocomis raneyi.   The Bigmouth Chub was all alone in the upper New River, surrounded by other Nocomis. 
Distribution of Nocomis platyrhynchus, Nocomis micropogon and Nocomis raneyi.  Nagle and Simons 2012. 
These and other Nocomis species arose from a common ancestral Nocomis. Let’s call him “Bob.”   Apparently the “Bob” chub moved into the ancient Teays River several million years ago.  (I don’t really know when, no one does for sure.  One day this may be answered by students of Nocomis).    
Populations of the “Bob” chub became vicariant, or isolated from other chubs to an extent that prevents or interferes with genetic interchange.  The Teays River originated in the Tertiary Period and at that time drained much of eastern North American in the pre-glacial period.  However, the original route of the ancient Teays was altered by glacial advances which created a massive ice dam blocking the northward-flowing Teays.   “Bob” experienced dramatic geologic and cycles of glaciation through evolutionary time that permitted the speciation of Nocomis platyrhynchus.  In allopatric speciation there is an extrinsic barrier to gene flow, which for the Bigmouth Chub was the Kanawha Falls at downstream limit and the Atlantic drainage divide at the upstream limits. The upper Teays followed the route of the present-day New River from near Blowing Rock, North Carolina.  Consequently, the descendents of “Bob” found refugia in the upper New River drainage during the Pleistocene and differentiated there. 

Today, the Bluehead Chub Nocomis leptocephalus also occurs in the upper New River. This species is widely distributed in piedmont streams from Mississippi to Virginia and may be five unique species (Nagle and Simons 2012).  Ichthyologists believe that Nocomis leptocephalus entered the New River drainage from the Roanoke drainage via a process called stream capture.  By the time of the stream capture, reproductive isolation mechanisms between the two Nocomis were in place so they would not interbreed.  
Bigmouth Chub.  Photo by Edward Burress.
The species name, platyrhynchus, refers to large mouth gape of the Bigmouth Chub.  The species exhibits sexual dimorphism.  The breeding adults have distinctive pink ventral coloration, olive-orange caudal fin, and yellow pectoral and pelvic fins. For an underwater view, watch the Bigmouth Chub swim in Walker Creek.  Nonbreeding females and juveniles have a dark horizontal lateral body stripe.   Bigmouth Chub inhabit medium- to large-sized tributaries and the mainstem New River.  These streams have a moderate gradient, warm, usually clear water, and a good mix of gravel to boulder substrates.  They may be found in both swift water and pools.  In a late summer investigation by Lobb and Orth (1988), the Bigmouth Chub were found only in riffles and adjacent runs and they avoided the shallowest depths and were always observed near the streambed. 
Non-reproductive adult Bigmouth Chub captured in the New River, Eggleston, Virginia
The most distinctive feature of the breeding male Bigmouth Chub is an enlarged nuptial crest and numerous tubercles on the head and snout.  The tubercles are rarely seen in small individuals (< 60mm SL) and the tubercle pattern is not fully developed until individuals exceed 100mm.     
Head of the breeding male Bigmouth Chub.
In the photo, note the pink coloration on ventral side of head and belly region.   Also, the tubercles do not extend to the occipital region in the Bigmouth Chub. The male Bluehead Chub has larger and fewer tubercles and no tubercles on the snout.  Therefore, potential mates can be recognized by presence or absences of tubercles on the snout in addition to coloration differences. 

Tubercle functions are the source of much speculation.  Tubercles possibly serve to warn other individuals who may infringe on the male's territory during nest building.  If the visual warning doesn’t work, head butting might.  Tubercles may assist in attracting a female mate or in maintaining contact during the spawning act.  Tubercles are shed after spawning.

During the spring, the male Bigmouth Chub uses his big mouth to construct spawning mounds in areas of small to large gravel, shallow water (15-75 cm), and moderate water velocity (10-70 cm/sec).   The gravel mound is an impressive alteration of the streambed and is constructed over many days and nights by a single breeding male.  The male may collect pebbles from as far as 10 meters from the nest.  Most mounds measured by Lobb and Orth (1988) were between 50-90 cm wide and 40-70 cm high and consisted of large gravels.  The behavior of mound construction is remarkably similar in the closely related Bigmouth Chub, River Chub, and Bull Chub.  Eugene Maurakis described this characteristic three-stage progression. 
Bigmouth Chub three-stage mound construction (a) concavity; (b) platform; and (c) mound with spawning trough.  Source: Maurakis et al. 1991.
Bigmouth Chub constructs the gravel mound in three distinct stages (a) excavated cavity with channel parallel to current; (b) platform constructed with particles from lateral margins; and (c) mound with a spawning trough in upstream location.    These three behavioral synapomorphies are unique to these three Nocomis and support their derivation from a common ancestor, “Bob.”  The spawning trough is where a single male and female breed.  The mound, modifies the local flow field creating an eddy behind the mound and slow current in the trough where eggs and sperm are deposited.  The large gravel mound enhances survival of embryos and larvae, which would otherwise be eaten by numerous egg predators.   The mound is such a perfect spawning location that other minnows are frequently observed spawning in the vicinity of the Bigmouth Chub gravel mound.   The Central Stoneroller Campostoma anomalum, Striped Shiner Luxilus chrysocephalus, Rosefin Shiner Lythrurus ardens, Rosyface Shiner Notropis rubellus, and Mountain Redbelly Dace Chrosomus oreas are some of the common nest associates with the Bigmouth Chub.
Photos of gravel mound nests of the Bigmouth Chub.
Top view by Brandon Peoples (left) and side view by Del Lobb (right).
The Bigmouth Chub is the result of millions of years of evolution, changing climate, and river erosion.  Recent molecular analyses suggest that it might be subsumed into Nocomis micropogon (Nagle and Simons 2012).  More study is needed of this minnow and the many other minnows that dominate our local streams.  Today we know very little about this endemic minnow and its history and role in its New River home.  It’s not a simple story to untangle.  You can blame it on the Pleistocene! 


Lobb, M.D., III, and D.J. Orth. 1988. Microhabitat use by the Bigmouth Chub Nocomis platyrhynchus in the New River, West Virginia.  The American Midland Naturalist 120(1):32-40.
Lobb, M.D., III, and D.J. Orth. 1991.  Habitat use by an assemblage of fish in a large warmwater stream.   Transactions of the American Fisheries Society 120(1):65-78.
Maurakis, E.G. 1998.  Breeding behaviors in Nocomis platyrhynchus and Nocomis raneyi (Actinopterygii: Cyprinidae). Virginia Journal of Science 49(4):227-236.
Maurakis, E.G., W.S. Woolcott, and M.H. Sabaj. 1991.  Reproductive-behavioral phylogenetics of Nocomis species-groups.  The American Midland Naturalist 126:103-110.

Nagle, B.C., and A.M. Simons. 2012.  Rapid diversification in the North American minnow genus Nocomis.  Molecular Phylogenetics and Evolution 63(3):639-649.         doi:10.1016/j.ympev.2012.02.013