Action Plan Eastern Pearlshell Natural Diversity Section June 2011

Species Action Plan:

Eastern pearlshell ( margaritifera)

Purpose and Goals

Purpose: This plan provides an initial five years blueprint for the actions needed to attain near-term and, ultimately, long-term goals for the conservation and recovery of the eastern pearlshell. The action plan is a living document and will be updated as needed to reflect progress toward those Figure 1. Eastern Pearlshell Mussel goals and to incorporate new information as (Margaritifera margitifera). Photo- it becomes available. PFBC. Goals: The immediate goal is to maintain Description: Linnaeus first described the the extant populations of eastern pearlshell eastern pearlshell in 1758. Strayer and Jirka in the Commonwealth and to protect its (1997) describe the shell characteristics as remaining habitat. The secondary goal is to “elongate, subelliptical to arched, thick (but enhance extant populations by improving often cracking when dried).” Shell size and increasing local habitat. Ultimately it is reaches up to 152 mm (Ortmann 1919). hoped the species will recover to the point Ortmann (1919) described the where it can be removed from the Pennsylvanian specimens (from the vicinity Pennsylvania list of endangered species (58 of Rene Mont) as the largest specimens ever Pa. Code §75.1). recorded for that time. Bogan (2005, Natural History correspondence) further notes that shell specimens are “somewhat inflated, somewhat cylindrical in cross-section, often becoming arctuate in older specimens.” : Class , Order consists of longitudinal Unionoida, Family ridges, sometimes broken (Bogan 2005, (margaritiferids), Eastern Pearlshell correspondence). dark brown (Margaritifera margaritifera, Linneaus to blackish, without rays. Pseudocardinal 1758). (Figure 1.) teeth are strong; however, lateral teeth

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nearly or entirely absent. The eastern (Salvelinus fontinalis). These salmonid pearlshell’s color varies from pearly species are found within the historic range white, to sometimes with pink or with purple of the eastern pearlshell and are stocked by tones. Pits are present where the the Pennsylvania Fish and Boat Commission muscle attaches to the shell. These pits, (PFBC). Specific salmonid host fish use by when examined closely, have a trailing edge Pennsylvania’s eastern pearlshell has not not unlike a shooting star. been determined. The eastern pearlshell diet is unknown, but presumed to be bacteria, Habitat: The eastern pearlshell is found in detritus, phytoplankton, and zooplankton. clean, low nutrient, calcium-poor, fast- flowing areas of small creeks to medium- Distribution and Status sized rivers where often it is the only mussel species (Smith 1976).

Life History: The eastern pearlshell has been Global and National Distribution: The described as the longest living invertebrate eastern pearlshell is a Holarctic species known and Bauer (1987) reports specimens found on the North American, Asian and > 100 years old. The eastern pearlshell is a European continents. Large populations short-term brooder (tachytictic), spawning remain in northern Russia (Varzuga River) yearly during mid-June through August and declining populations (little to no (Hastie and Young 2003, Young and recruitment) remain in Western Europe. Williams 1984). Conner (1909) noted that The North American distribution of eastern the Pennsylvania breeding season occurred pearlshell includes Atlantic Slope basins that during June and August. Hastie and Young range from Labrador south to Pennsylvania (2003) report glochidia being released into (Figure 2). In the United States, this species the water column beginning mid-July and is distributed from Maine to Pennsylvania. tapering off around the beginning of New York tributaries to Lake Ontario are September. The eastern pearlshell uses considered the western extent of the species salmonid species as its host, including range and Pennsylvania’s Delaware River rainbow trout (Oncorhynchus mykiss), basin the southern extent. brown trout (Salmo trutta) and brook trout

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Pennsylvania Distribution: Historically, the eastern pearlshell’s Pennsylvania range probably included the entire Schuylkill River basin. Presently, only two populations are known to exist in that basin (Figure 3).

The eastern pearlshell is also likely to have historically occupied portions of the Delaware River mainstem and tributaries. Live specimens were collected from the upper Delaware River mainstem in 2000 (Lellis 2000, unpublished data). Additional populations may occur in other under- surveyed river basins (e.g. Susquehanna River) or stream reaches (e.g. West Branch Delaware River) or tributaries.

Pennsylvania Legal Status: Endangered Figure 2. North American distribution of the Eastern Pearshell (M. margaritifera) State Rank: S1 – Critically Imperiled (NatureServe 2010). Global Status: G4 – Apparently Secure

The eastern pearlshell will be considered for delisting when 80% of the historically- occupied streams contain three distinct naturally-reproduced year classes (PABS Bivalve Committee listing criteria).

Figure 3. Distribution of the Eastern Pearlshell in Pennsylvania. (Source: PFBC)

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Management Status peak production of coal. A number of streams which may have historically contained eastern pearlshell were probably destroyed by mine-related pollution. The majority of all of the historic streams have been visited at least once by PFBC Current Threats: staff. Comprehensive assessments of historic streams have been restricted due to limited Habitat degradation: Threats to eastern permissions from landowners and staff pearlshell include riparian habitat loss, availability. sedimentation, incidental harvest, non-point Population trends: source pollution from poor agricultural One population in the Schuylkill River basin practices, and pollution from coal mining appears stable while the status of the activities. Additionally, in the absence of Delaware River population is unknown. best management practices implementation, eastern pearlshell populations could be Threats negatively affected by actions such as road construction, stream channel modifications,

logging activities, agricultural activities, The following is a description of past and land use changes, pesticide use, and other present threats that have lead to the decline projects or activities in the watershed (see of eastern pearlshell populations in Cosgrove and Hastie 2001). Furthermore, Pennsylvania. Where appropriate, specific populations inhabiting relatively short actions to reduce or eliminate threats are stream reaches having multiple bridges or included in the list of conservation and ford crossings are likely to have more recovery activities following this discussion. exposure to single catastrophic events such Historic Threats: Historically the eastern as toxic spills which could potentially pearlshell was highly sought for the high annihilate the population during a single quality freshwater produced by the event. Several authors (e.g., Hastie et al. species (Kunz and Stevenson 1908). 2003, Galbraith et al. 2010) indicate that Ortmann (1919) indicated that the climate change may have deleterious effects “recklessness of the -hunters has nearly on mussel populations. Eastern pearlshells exterminated it” from the Schuylkill River and their hosts would be particularly basin. vulnerable to elevated water temperatures and large flood events associated with an In addition to the pearl industry, portions of increase in precipitation. the Schuylkill River region were heavily mined for anthracite coal. The time of Flow alteration. A primary threat to the Ortmann’s 1919 publication was near the continued existence of eastern pearlshell is

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flow and habitat alteration due to placement Pennsylvania’s eastern pearlshell or operation of existing impoundments. The populations. Further exacerbating potential effects of impoundments on mussel genetic problems, small population sizes populations are well documented (Watters reduce the intra-population reservoirs of 2000) Gene dispersal via glochidia transport genetic variability. The apparent small through the water column or passage of fish population size of one extant population around the dams on occupied streams has suggests that this population may suffer been rendered unlikely except during from reduced genetic variability. Loss of extreme flood events. The construction of genetic diversity could adversely affect the dams on historically occupied streams has species’ ability to evolve and respond to eliminated large stretches of lotic habitat. natural changes. Soule (1980) recommended The conversion of habitat from a lotic to a minimum of 500 individuals to maintain lentic environment has altered the thermal genetic variability and evolutionary potential and flow regimes within the impoundments within a population. by decreasing flow, increasing sedimentation, and creating thermal Invasive species. The effects of predation stratification. on native fish species and/or competition for food and breeding habitat from The operation of dams on the Pepacton nonindigenous fish species can result in Reservoir (East Branch Delaware River) and drastic declines in, or even the elimination Cannonsville Reservoir (West Branch of, the native fish fauna. These declines Delaware River) has the potential to alter could include the salmonid species habitat and persistence of eastern pearlshell necessary for the eastern pearlshell to in the mainstem Delaware River. Both complete their life cycles. reservoirs serve as major water supplies to New York City and the dams are operated to The spread of the diatom alga didymo maintain water supply as well as to meet a (Didymosphenia geminata) into eastern minimum mainstem flow target at Montague pearlshell waterways is the most immediate (river mile 246.8). Current proposals to invasive species threat to the eastern revise release of water from two other pearlshell. Didymo is currently known from impoundments on the Mongaup and the upper Delaware River mainstem where Lackawaxen Rivers (located upstream of eastern pearlshell has been collected. Montague) may affect the quantity of water Proliferation of didymo could result in the available at the known eastern pearlshell loss of mussel related ecosystem services locations. (water filtration) as a result of the burial of beneath didymo mats or loss of Genetics. Geographic isolation restricts the mussel reproductive capacity due to changes natural exchange of genetic material among in host fish populations or behaviors.

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Predation. Predation may also threaten the ii. Begin landowner outreach. continued existence of the eastern pearlshell iii. Complete restoration plans. in the Commonwealth. Shells of the species c. Implement planned restoration have been found in raccoon middens along projects at five identified project occupied streams and the species is sites. presumably consumed by other mammals d. Maintain current PFBC trout such as muskrats and minks. While stocking within Schuylkill River predation is not thought to be a significant basin. threat to healthy mussel populations, it could limit the recovery of endangered mussel 2) Identify new streams in Schuylkill River species or contribute to the local extirpation basin with potential to harbor eastern of mussel populations already depleted by pearlshell. other factors (Neves and Odum 1989). 3) Determine restoration potential of historically-occupied Schuylkill River Conservation and Recovery basin streams.

4) Restore degraded habitat in historically- occupied Schuylkill River basin streams. Conservation Actions B. Delaware River Basin A. Schuylkill River Basin

1) Work towards the protection, 1) Work towards the protection, conservation and enhancement of extant conservation and enhancement of extant populations. populations. a. Continue to work with Federal and a. Gather baseline quantitative state government agencies to develop information. flow recommendations that are i. Characterize eastern pearlshell protective of eastern pearlshell. populations at extant locations. b. Encourage the development of ii. Characterize the physical habitat regulations and policies that would and the host fish community at reduce the introduction and spread of extant locations. aquatic invasive species. b. Identify degraded habitat in 2) Gather additional baseline information occupied portions of the Schuylkill on Delaware River population. drainage. a. Characterize eastern pearlshell i. Conduct desktop and ground populations at extant locations. truth analyses.

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b. Characterize the physical habitat, References host fish community, and the macroinvertebrate community at Bauer, G. 1979. Untersuchungen zur extant locations. fortpflanzungsbiologie der flubperlmuschel im Fichtelgebirge. 3) Survey the West Branch of the Delaware [Studies on the reproductive biology of River for the presence of eastern the pearlshell mussel populations. Margaritifera margaritifera in the Fichtelbirge]. Archiv fuer C. Monitoring Hydrobiologie 85:152-165

1) Initiate monitoring of existing Bauer, G. 1987. Reproductive strategy of the populations freshwater pearl mussel Margaritifera a. Identify and establish monitoring at margaritifera. Journal of four sampling sites within occupied Ecology 56: 691-704. streams. b. Conduct monitoring every three Bauer, G. 1987. The parasitic stage of the years. freshwater pearl mussel (Margaritifera margaritifera L.) III. Host D. Reintroduction and relationships. Archiv fuer Hydrobiologie Augmentation Supplement 76(4):413-423.

1) Plan for the reintroduction of eastern Bauer, G., and C. Vogel. 1987. The parasitic pearlshells in suitable waters within their stage of the freshwater pearl mussel historically-occupied range. (Margaritifera margaritifera L.) I. Host 2) Implement planned reintroductions as response to glochidiosis. Archiv fuer deemed appropriate. Hydrobiologie Suppl. 76(4):393-402.

Bruno, D.W., A.H. McVicar, and I.F. Waddell. 1988. Natural infection of farmed Atlantic salmon, Salmo salar L., parr by glochidia of the freshwater pearl mussel, Margaritifera margairtifera L. Bulletin of the European Association of Fish Pathologists 8(2):23-26.

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Buddensiek, V. 1995. The culture of Fustish, C.A. and R.E. Milleman. 1978. juvenile freshwater pearl mussels Glochidiosis of salmonid fishes. II. Margaritifera margaritifera L. in cages: Comparison of tissue response of Coho a contribution to conservation and Chinook salmon to experimental programmes and the knowledge of infection with Margaritifera habitat requirements. Biological margaritifera (L.) (Pelecypoda: Conservation 74(?):33-40. Margaritanidae). The Journal of Parasitology 64(1): 155-157. Clarke, A.H., and C.O. Berg. 1959. The freshwater mussels of central New York. Galbraith, H.S., Spooner, D.E. and C.C. Memoir Cornell University Agricultural Vaughn. 2010. Synergistic effects of Experiment Station, N.Y. State College regional climate patterns and local water of Agriculture, Ithaca, N.Y. 367:1-79. management on freshwater mussel communities. Biological Conservation Conner, C.H. 1909. Supplementary notes on 143: 1175-1183. the breeding seasons of the Unionidae. Nautilus Volume 22: 111-112. Geist, Juergen. 2010. Strategies for the conservation of endangered freshwater Cosgrove, P.J. and L.C. Hastie. 2001. pearl mussels (Margaritifera Conservation of threatened freshwater margaritifera L.): a synthesis of pearl mussel populations: river Conservation Genetics and Ecology. management, mussel translocation and Hydrobiologia 644: 69-88 conflict resolution. Biological Conservation 99: 183- 190. Harms, W. 1907. Zur Biologie und Entwicklungsgeschicte der Cunjak, R.A., and S.E. McGladdery. 1991. Flussperlmuschel (Margaritifera The parasite-host relationship of margaritifera Dupuy). Zoologie Anz 31: glochidia (:Margaritiferidae) on 814-824. the gills of young-of-the-year Atlantic salmon (Salmo salar). Canadian Journal Hastie, L.C., Cosgrove, P.J., Ellis, N and of Zoology 69(2):353-358. M.J. Gaywood. 2003. The threat of climate change to freshwater pearl Davis, H.S. 1934. Care and diseases of trout. mussel populations. Ambio 32(1): 40— U.S. Bureau of Fisheries Investigational 46. Report (22):1-69.

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Hastie, L.C. and M.R. Young. 2003. Timing Nezlin, L.P., Cunjak, R.A., Zotin, A.A. and of spawning and glochidial release in V.V. Ziuganov. 1994. Scottish freshwater pearl mussel morphology of the freshwater pearl (Margaritifera margaritifera) mussel (Margaritifera margaritifera) populations. Freshwater Biology 48: and glochidiosis of Atlantic salmon 2107-2117. (Salmo salar): a study by scanning electron microscopy. Canadian Journal Hruska, J. 1992. The freshwater pearl of Zoology 72: 15-21. mussel in South Bohemia: evaluation of the effect of temperature on Ortmann, A.E. 1911. Monograph of the reproduction, growth and age structure najades of Pennsylvania. Part I. of the population. Archiv für Anatomical investigations. Part II. The Hydrobiologie 126(2):181-191. system of the North American najades. Memoirs of the Carnegie Museum Karna, D.W. and R.E. Milleman. 1978. Volume 4, No. 6 Glochidiosis of salmonid fishes. III. Comparative susceptibility to natural Ortmann, A.E. 1919. Monograph of the infection with Margaritifera naiades of Pennsylvania. Part III. margaritifera (L.) (Pelecypoda: Systematic account of the genera and Margaritanidae) and associated species. Memoirs of the Carnegie histopathology. The Journal of Museum Volume 8, No. 1. Parasitology 64(3): 528-537. Silkenat, W., Silkenat, M., Klupp, R., Kunz, G.F. and C.H. Stevenson. 1908. The Schmidt, S., Wenz, G., Eicke, L., and G. Book of the Pearl: It’s History, Art, Bauer. 1991. Errichtung und Sicherung Science and Industry. The Century Co., schutzwürdiger Teile von Natur und New York. Republished by Dover Landschaft mit gesamtstaatlich Publications, Inc. 2001. repräsentativer Bedeutung. Erfahrungen mit einem Projekt zur Rettung der Meyers, T.R. and R.E. Milleman. 1977. Flußperlmuschel. Natur und Landschaft Glochidiosis of salmonid fishes. I. 66:63-67. Comparative susceptibility to experimental infection with Smith, D.G. 1976. Notes on the biology of Margaritifera margaritifera (L.) Margaritifera margaritifera (Pelecypoda: Margaritanidae). The margaritifera (Lin.) in central Journal of Parasitology 63(4): 728-733. Massachusetts. American Midland Naturalist 96(1): 252-256.

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Soule, M.E. 1980. Thresholds for survival: Zhadin, Z.D. 1952, Mollyuski presnykh i maintaining fitness and evolutionary solonovatykh vod SSSR. [Keys to the potential. Pages 151-169 in M.E. Soule fauna of the USSR]. Academy of and B.A. Wilcox, eds. Conservation Sciences of the U.S.S.R. Israel Program Biology. Sinauser Associates, for Scientific Translation, Jerusalem. Sunderland, MA. 46:1-368.

Strayer, D.L. and K.J. Jirka. 1997. The pearly mussels of New York State. New York State Museum. Memoir 26. The University of the State of New York. The State Education Department. 113 pages, 27 plates.

Watters, G.T. 2000. Freshwater mussels and water quality: a review of the effects of hydrologic and instream habitat alteration. Proceedings of the First Freshwater Mollusk Conservation Society Symposium. Pages 261-274.

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Young, M., G.J. Purser, and B. Al-Mousawi. 1987. Infection and successful reinfection of brown trout[Salmo trutta L.] with glochidia of Margaritifera margaritifera (L.). American Malacological Bulletin 5(1):125-128.

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