Geology topics

T.B. Grabowski

Publications and source records attributed to T.B. Grabowski.

8 recordsLinked to original sources

USGS2011

Seasonal and diel movements and habitat use of robust redhorses in the Lower Savannah River, Georgia and South Carolina

The robust redhorse Moxostoma robustum is a large riverine catostomid whose distribution is restricted to three Atlantic Slope drainages. Once presumed extinct, this species was rediscovered in 1991. Despite being the focus of conservation and recovery efforts, the robust redhorse's movements and habitat use are virtually unknown. We surgically implanted pulse-coded radio transmitters into 17 wild adults (460-690 mm total length) below the downstream-most dam on the Savannah River and into 2 fish above this dam. Individuals were located every 2 weeks from June 2002 to September 2003 and monthly thereafter to May 2005. Additionally, we located 5-10 individuals every 2 h over a 48-h period during each season. Study fish moved at least 24.7 ?? 8.4 river kilometers (rkm; mean ?? SE) per season. This movement was generally downstream except during spring. Some individuals moved downstream by as much as 195 rkm from their release sites. Seasonal migrations were correlated to seasonal changes in water temperature. Robust redhorses initiated spring upstream migrations when water temperature reached approximately 12??C. Our diel tracking suggests that robust redhorses occupy small reaches of river (???1.0 rkm) and are mainly active diurnally. Robust redhorses were consistently found in association with woody debris and gravel streambed sediments along the outer edge of river bends. Fish exhibited a high degree of fidelity to both overwintering and spawning areas. Our observations of long-distance seasonal migrations suggest that successful robust redhorse conservation efforts may require an ecosystem management approach. ?? Copyright by the American Fisheries Society 2006.

Transactions of the American Fisheries Society↗

USGS2010

First record of carpiodes velifer (Highfin Carpsucker) in the Apalachicola River, Florida

We document the discovery of Highfin Carpsucker in the Apalachicola River, FL. Three specimens were captured between river kilometer 170-171 on the Apalachicola River in the vicinity of Jim Woodruff Lock and Dam during spring 2007, The specimens were captured within a reach 0.5-1.0 km downstream from the dam and just upstream from a major spawning area for several other catostomids. This is the first record of the species east of the Choctawhatchee River, FL-AL, and is a range extension of 185 km eastward into the Florida Panhandle region of the Northern Gulf of Mexico Coast.

Southeastern Naturalist↗

USGS2008

Size of spawning population, residence time, and territory shifts of individuals in the spawning aggregation of a riverine catostomid

Little is known about the behavior of individual fish in a spawning aggregation, specifically how long an individual remains in an aggregation. We monitored Moxostoma robustum (Cope) (Robust Redhorse) in a Savannah River spawning aggregation during spring 2004 and 2005 to provide an estimate of the total number of adults and the number of males comprising the aggregation and to determine male residence time and movements within a spawning aggregation. Robust Redhorse were captured using prepostioned grid electrofishers, identified to sex, weighed, measured, and implanted with a passive integrated transponder. Spawning aggregation size was estimated using a multiple census mark-and-recapture procedure. The spawning aggregation seemed to consist of approximately the same number of individuals (82-85) and males (50-56) during both years of this study. Individual males were present for a mean of 3.6 ?? 0.24 days (?? SE) during the 12-day spawning period. The mean distance between successive recaptures of individual males was 15.9 ?? 1.29 m (?? SE). We conclude that males establish spawning territories on a daily basis and are present within the spawning aggregation for at least 3-4 days. The relatively short duration of the aggregation may be the result of an extremely small population of adults. However, the behavior of individuals has the potential to influence population estimates made while fish are aggregated for spawning.

Southeastern Naturalist↗

USGS2007

Demographics of the spawning aggregations of four catostomid species in the Savannah River, South Carolina and Georgia, USA

Differences in the life history strategies employed by otherwise ecologically similar species of a fish assemblage may be an important factor in the coexistence of these species and is an essential consideration in the conservation and management of these assemblages. We collected scales to determine age and growth of four species of the catostomid assemblage (northern hogsucker Hypentelium nigricans, spotted sucker Minytrema melanops, notchlip redhorse Moxostoma collapsum and robust redhorse Moxostoma robustum) of the Savannah River, Georgia-South Carolina in spring 2004 and 2005. Robust redhorse was the largest species; reaching sexual maturity at an older age and growing faster as a juvenile than the other species. Spotted sucker did not achieve the same size as robust redhorse, but reached sexual maturity at younger ages. Notchlip redhorse was intermediate between the abovementioned two species in age at maturity and size. Northern hogsucker was the smallest species of the assemblage and reached the sexual maturity at the age of three. Both robust redhorse and spotted sucker were sexually dimorphic in size-at-age. The range of life history strategies employed by Savannah River catostomids encompasses the range of life history strategies exhibited within the family as a whole. ?? 2007 Blackwell Munksgaard.

Ecology of Freshwater Fish↗

USGS2007

Spatial and temporal segregation of spawning habitat by catostomids in the Savannah River, Georgia and South Carolina, U.S.A.

Spawning aggregations of five species of catostomids were observed on the two mid-channel gravel bars of the Savannah River, Georgia and South Carolina, in 2004 and 2005 to assess the degree of spatial and temporal overlap in the use of this habitat and determine the habitat preferences leading to segregation. Spawning catostomids showed a considerable amount of temporal overlap in their use of these mid-channel gravel bars. The observed temporal overlap was consistent between 2004 and 2005 and corresponded to temperatures at which species were present. The distribution of catostomids was not uniform at the upstream gravel bar. Carpsuckers Carpiodes sp., spotted sucker Minytrema melanops and robust redhorse Moxostoma robustum both demonstrated some spatial overlap with notchlip redhorse Moxostoma collapsum; however, their overall distributions were different from one another. Northern hogsucker Hypentelium nigricans was present across the gravel bars, apparently as an egg predator. Spawning catostomids segregated based on flow, depth, slope and substratum size. Whether due to limited habitat availability or changes in the timing of reproduction due to altered cues, temporal and spatial overlap occurs between spawning catostomids despite the apparent partitioning of available spawning habitat. It is unclear, however, if this overlap results in excessive mortality in the early life-history stages of these species. Results suggest spatial overlap among catostomid species was minimized due to species spawning in areas within a narrow range of conditions. Intraspecific interactions such as nest site superimposition or disturbance may be a concern. ?? 2007 The Fisheries Society of the British Isles.

Journal of Fish Biology↗

USGS2007

Effects of flow fluctuations on the spawning habitat of a riverine fish

Shallow-water, lithophilic spawning fishes are among the most vulnerable to anthropogenic fluctuations in water levels. We monitored water levels and environmental conditions at the nest sites of Moxostoma robustum (Robust Redhorse) on a main-channel gravel bar in the Savannah River, GA-SC During the course of the 2005 spawning season, over 50% of the observed nest sites were either completely dewatered or left in near zero-flow conditions for several days. This occurred on two separate occasions, once early during the spawning season and then again near its conclusion. We hypothesize the habitat preferences of spawning Robust Redhorse leave them vulnerable to water-level fluctuations, and this phenomenon may be widespread in regulated river systems.

Southeastern Naturalist↗

USGS2005

Use of prepositioned grid electrofishers for the collection of robust redhorse broodstock

We investigated the potential of prepositioned grid electrofishers as a means of collecting broodstock for the rare robust redhorse Moxostoma robustum. We found that combined with visual observation, this technique allowed for the efficient capture of fish in breeding condition. We were able to harvest eggs in the field and bring only fertilized eggs into the hatchery. There was no need to induce spawning hormonally. Although their use is limited by water depth and clarity, prepositioned grid electrofishers used in conjunction with visual observation warrants further consideration as an effective tool for the collection of reproductively active broodstock for conservation purposes. ?? Copyright by the American Fisheries Society 2005.

North American Journal of Aquaculture↗

USGS2004

Tag Retention and Survivorship of Hatchery Rainbow Trout Marked with Large-Format Visible Implant Alphanumeric Tags

Large-format visible implant alphanumeric (VIalpha) tags were implanted into 15,400 rainbow trout Oncorhynchus mykiss. Tag retention after 25 d was 82.6%, and survivorship was 92.8%. The results of this study compare favorably with those of similar studies on other species and suggest that large-format VIalpha tags are an appropriate choice for studies requiring the individual identification of larger rainbow trout.

North American Journal of Aquaculture↗