Decline of the Frecklebelly Madtom in the Pearl River Based on Contemporary and Historical Surveys

Abstract

Abstract.-The Pearl River has experienced numerous human-caused disturbances since the 1950s, including completion of a navigation channel, reservoir construction, and channel modifications on the main stem of the river. These types of disturbances are known to negatively impact the biotic and abiotic components of riverine ecosystems. Since the 1960s, several fish species in the drainage have declined in abundance or have been extirpated from the drainage. We undertook this study to assess the current conservation status of the frecklebelly madtom Noturus munitus in the Pearl River drainage. A 1999 survey of 53 sites within the historic range of the frecklebelly madtom yielded only 13 specimens from eight localities. We also examined historical population trends for the frecklebelly madtom and other benthic fishes using archived museum material . After standardizing for variation in collection effort, analysis of long-term collection data indicated that frecklebelly madtom populations have declined significantly since the 1960s. Despite greater sampling effort in the postmodification period , frecklebelly madtoms were most abundant in samples during the modification period (1950)(1951)(1952)(1953)(1954)(1955)(1956)(1957)(1958)(1959)(1960)(1961)(1962)(1963)(1964). Similar declines were observed for the brighteye darter Etheostoma lynceum, a gravel-riffle-dependent species. Other percid taxa (including the crystal darter Crystallaria asprella (formerly Ammocrypta asprella), the saddleback darter Percina vigil, the Gulf logperch P. suttkusi, and the dusky darter P. sciera) showed no significant changes between modification and postmodification periods. However, benthic taxa (including the naked sand darter Ammocrypta beani, longnose shiner Notropis longirostris, channel catfish Ictalurus punctatus, hogchoker Trinectes maculatus, gulf darter E. swaini, speckled chub Macrhybopsis aestivalis, and silver chub M. storeriana) increased in abundance between modification and postmodification study periods. We suggest that channel changes and the loss of gravel substrates are related and are contributing to the decline of the frecklebelly madtom in the Pearl River drainage.

Net local removal of floodplain sediment by river meander migration

“…Two notable engineering structures are present near the Pearl/Bogue Chitto River study reaches. The first is the abandoned Pearl River navigational canal which intersects portions of both the Pearl and Bogue Chitto Rivers and was maintained for commercial use from 1956 into the 1970s (Piller et al, 2004). Since we observed calm water in the canal during a high water event, we assume that the canal has had few geomorphic consequences.…”

Status of the Imperiled Frecklebelly Madtom, Noturus munitus (Siluriformes: Ictaluridae): A Review of Data from Field Surveys, Museum Records, and the Literature

“…Examination of available museum records reveals a similar pattern in the Alabama and Tombigbee rivers (Table 1), with few collections after 1970 producing specimens, in contrast to the Cahaba River collections, in which N. munitus seems to have remained fairly common. While these museum datasets undoubtedly omit some records, a general trend similar to the findings of Piller et al (2004) is apparent.…”

“…Noturus munitus was once fairly abundant in appropriate habitat throughout its range, with night-time collections on large-river gravel shoals before the late 1960s regularly producing large collections of specimens in the hundreds (Supplementary Table 1, available only online at http://dx.doi.org/10.1656/S593.s1; Piller et al 2004). One of the most extensive analyses of historic population trends was conducted by using museum collection data from the Pearl River from 1950 to 1988.…”

“…All collections were made at night using a mesh seine (4.6 x 1.2 m or 3.0 x 1.2 m) and backpack electrofishing unit. Piller et al (2004): Spring-Fall 1999, Pearl River. Piller andcolleagues (2004) surveyed 53 historic collection sites for N. munitus in the main stem of the Pearl River as well as its tributaries (Fig.…”

Spatio‐temporal patterns of fish assemblage structure in a coastal plain stream: appropriate scales reveal historic tales

“…1), drains approximately 22,688 km² and is nearly 640 km in length. The ichthyofauna of the Pearl River system has been studied for more than half of a century (Gunning & Suttkus 1985, 1990, 1991Love & Taylor 2004;Piller et al 2004;Tipton et al 2004;Stewart et al 2005); however, no study has examined the assemblage structure dynamics of its fishes across time and space. The ichthyofauna of the Pearl River system has been studied for more than half of a century (Gunning & Suttkus 1985, 1990, 1991Love & Taylor 2004;Piller et al 2004;Tipton et al 2004;Stewart et al 2005); however, no study has examined the assemblage structure dynamics of its fishes across time and space.…”