Academic journal article The American Midland Naturalist

Hobbseus Yalobushensis, a Crayfish of Intermittent Streams: Biotic and Habitat Associations, Life History Characteristics, and New Localities

Academic journal article The American Midland Naturalist

Hobbseus Yalobushensis, a Crayfish of Intermittent Streams: Biotic and Habitat Associations, Life History Characteristics, and New Localities

Article excerpt

Introduction

Defining a species' conservation status and applying effective and efficient conservation efforts requires information about distribution, abundance trends, habitat needs, autecology, and life history. A recent global assessment of crayfish conservation status categorized 21% of species as "data deficient" (Richman et aL, 2015). Most "data deficient" assessments resulted from lack of basic information about species' distributions, abundances, or threats. The percentage of "data deficient" species equaled the combined percentages of species categorized as extinct, critically endangered, and endangered. The highest number of data deficient species globally was from the southeastern U.S.A. (Richman et aL, 2015). Indeed, litde or nothing is published about the ecology and life history of many crayfish species in Mississippi.

The crayfish genus Hobbseus is nearly endemic to Mississippi, with the ranges of six of the seven species restricted to the state, and the seventh extending into Alabama. Hobbseus species are small and relatively short-lived crayfishes, often occurring in temporary waters. Beyond the species descriptions, no further publications have focused on any Hobbseus species. In the latest International Union for the Conservation of Nature (IUCN) Red List review (IUCN 2013), three Hobbseus species were ranked "data deficient," three "endangered," and one "least concern." Population trends were unknown for all seven species.

Hobbseus yalobushensis is the only Hobbseus species in the Mississippi River basin, where it is known from only six localities in southern headwater tributaries of the Yalobusha River drainage in three counties (Fitzpatrick and Busack, 1989; Fitzpatrick, 1996) (Fig. 1). Fitzpatrick (2002) also reported the species from Attala and Choctaw counties, Mississippi but gave no localities and referenced no collection records or voucher specimens to corroborate his report. The species is ranked "Endangered" by the IUCN Red List due to a fragmented range <5000 km2 and observed, inferred, or projected continuing decline in the area, extent and/or quality of habitat (IUCN 2013). The species is also ranked "Endangered" by the American Fisheries Society (Taylor et al., 2007), "G2 Imperiled" by NatureServe (2013), and "Tier 1" (in need of immediate conservation action and/or research) by Mississippi (MDWFP, 2005).

Hobbseus yalobushensis life history is poorly documented. Individuals used streams from January to June (Fitzpatrick and Busack, 1989), suggesting the species is a secondary burrower. Form I males were collected in March, April, and June, and immature individuals were collected from January through March. The largest individual reported was a female with a carapace length (CL) of 21.8 mm. Form I males ranged from 14.8 to 18.0 mm CL.

During a study on another rare crayfish, Procambams lylei, we found a new H. yalobushensis locality in central Mississippi. We expanded our study to learn more about H. yalobushensis distribution, habitat associations, ecology, and life history. Our objectives were to: (1) identify additional H. yalobushensis localities in a landscape managed intensively for loblolly pine (Pinus taeda) production, (2) relate stream size, water quality variables, and flow permanence to species presence or density, (3) characterize the aquatic community in relation to H. yalobushensis density, (4) better define elements of the species' life history, and (5) compile unpublished H. yalobushensis localities from post-1989 collection records.

Methods

STUDY AREA

Hobbseus yalobushensis occurs entirely within the Southern Hilly Gulf Coastal Plain ecoregion (65d), characterized by dissected irregular plains, rounded hills with gently to strongly sloping side slopes, and some wide floodplains with broad terraces (Chapman et ah, 2004). Streams are low to moderate gradient with sand or clay substrates. Forests are mixed hardwood and pine (Pinus spp. …

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