F. Douglas Martin

Terrestrial Activity, Abundance and Species Richness of Amphibians in Managed Forests in South Carolina

Abstract We determined the relative abundance, days of surface activity and indices of species diversity, evenness and richness for amphibians inhabiting three differently managed forests surrounding a Carolina bay in South Carolina following restoration. We collected animals daily for 3 y (Oct. 1993–Sept. 1996) using drift fences with pitfall traps in three forest types: loblolly pine (Pinus taeda), slash pine (P. elliotti) and mixed hardwoods (predominantly oak, Quercus spp. and hickory, Carya spp.). Captured animals were marked and recaptures were recorded but not included in statistical analyses, except in our evaluation of activity. We compared results to those of a more limited study conducted before restoration. Amphibians were significantly more numerous and more active in the mixed hardwood forest than in the pine forest types. However, the hardwood forest had the lowest species diversity in 2 of the 3 y of the study. The slash pine habitat had the highest diversity in all 3 y and for the 3 y combined. Because the evenness index (J′) values differ in step with the species diversity index (H′) it appears that the evenness component of diversity, rather than the richness component, is what is determining H′ variation. A summer subset of these data and summer data from an earlier study of 1977–1978 is in marked contrast with yearlong patterns. For our summer data each forest type had the highest H′ value in one of the years of the study and again the J′ values parallel the differences in H′. Large numbers of southern toads (Bufo terrestris) reduced evenness, and therefore species diversity, for all three habitats particularly the mixed hardwoods where this species was especially abundant. Proportionally lower numbers of B. terrestris in the summer samples increased J′ and H′ indices. Overall lower abundance and H′ values in the summers of 1994–1996 compared with 1977–1978 may be the result of habitat alteration during the restoration of the Carolina bay.

Assessing historical fish community composition using surveys, historical collection data, and species distribution models.

Accurate establishment of baseline conditions is critical to successful management and habitat restoration. We demonstrate the ability to robustly estimate historical fish community composition and assess the current status of the urbanized Barton Creek watershed in central Texas, U.S.A. Fish species were surveyed in 2008 and the resulting data compared to three sources of fish occurrence information: (i) historical records from a museum specimen database and literature searches; (ii) a nearly identical survey conducted 15 years earlier; and (iii) a modeled historical community constructed with species distribution models (SDMs). This holistic approach, and especially the application of SDMs, allowed us to discover that the fish community in Barton Creek was more diverse than the historical data and survey methods alone indicated. Sixteen native species with high modeled probability of occurrence within the watershed were not found in the 2008 survey, seven of these were not found in either survey or in any of the historical collection records. Our approach allowed us to more rigorously establish the true baseline for the pre-development fish fauna and then to more accurately assess trends and develop hypotheses regarding factors driving current fish community composition to better inform management decisions and future restoration efforts. Smaller, urbanized freshwater systems, like Barton Creek, typically have a relatively poor historical biodiversity inventory coupled with long histories of alteration, and thus there is a propensity for land managers and researchers to apply inaccurate baseline standards. Our methods provide a way around that limitation by using SDMs derived from larger and richer biodiversity databases of a broader geographic scope. Broadly applied, we propose that this technique has potential to overcome limitations of popular bioassessment metrics (e.g., IBI) to become a versatile and robust management tool for determining status of freshwater biotic communities.

Impact of Forest Seral Stage on use of Ant Communities for Rapid Assessment of Terrestrial Ecosystem Health

Abstract Bioassessment evaluates ecosystem health by using the responses of a community of organisms that integrate all aspects of the ecosystem. A variety of bioassessment methods have been applied to aquatic ecosystems; however, terrestrial methods are less advanced. The objective of this study was to examine baseline differences in ant communities at different seral stages from clear cut to mature pine plantation as a precursor to developing a broader terrestrial bioassessment protocol. Comparative sampling was conducted at nine sites having four seral stages: clearcut, 5 year recovery, 15 year recovery, and mature stands. Soil and vegetation data were also collected at each site. Ants were identified to genus. Analysis of the ant data indicated that ants respond strongly to habitat changes that accompany ecological succession in managed pine forests, and both individual genera and ant community structure can be used as indicators of successional change. Ants exhibited relatively high diversity in both early and mature seral stages. High ant diversity in mature seral stages was likely related to conditions on the forest floor favoring litter dwelling and cold climate specialists. While ants may be very useful in identifying environmental stress in managed pine forests, adjustments must be made for seral stage when comparing impacted and unimpacted forests.

Using RNA-seq to determine patterns of sex-bias in gene expression in the brain of the sex-role reversed Gulf Pipefish (Syngnathus scovelli)

Sex-bias in gene expression is a widespread mechanism for controlling the development of phenotypes that differ between males and females. Most studies on sex-bias in gene expression have focused on species that exhibit traditional sex-roles (male-male competition and female parental care). By contrast the Syngnathid fishes (sea horses, pipefish, and sea dragons) are a group of organisms where many species exhibit male brooding and sex-role reversal (female-female competition for mates and paternal parental care), and little is known about how patterns of sex-bias in gene expression vary in species with sex-role reversal. Here we utilize RNA-seq technology to investigate patterns of sex-bias in gene expression in the brain tissue of the Gulf Pipefish (Syngnathus scovelli) a species that exhibits sex-role reversal. Gene expression analysis identified 73 sex-biased genes, 26 genes upregulated in females and 47 genes upregulated in males. Gene ontology analysis found 52 terms enriched for the sex-biased genes in a wide range of pathways suggesting that multiple functions and processes differ between the sexes. We focused on two areas of interest: sex steroids/hormones and circadian rhythms, both of which exhibited sex-bias in gene expression, and are known to influence sexual development in other species. Lastly, the work presented herein contributes to a growing body of genome data available for the Syngnathids, increasing our knowledge on patterns of gene expression in these unusual fishes.

Population of variable platyfish (Xiphophorus variatus) established in Waller Creek, Travis County, Texas

Abstract The variable platyfish (Xiphophorus variatus), native to Gulf Coast drainages of northern Mexico, is a popular aquarium fish with a long history of introduction globally. We document the first Texas occurrence of this species, and its persistence in highly urban Waller Creek in the city of Austin since at least 2004. The population appears to be limited to Waller Creek, having not yet been found in neighboring creeks where similar habitat exists. We observed individuals in situ and in the lab surviving in 7°C water, well below published thermal minima, and report its persistence through one of the coldest winters in Austins recorded history. Its persistence may be due to a combination of its cold tolerance and the presence of thermal refuges. In the lab we found that individuals purchased in a local pet store and individuals from Waller Creek had the same cold tolerance.

Update on the Fishes of Texas Project

Poster presentation presented at the 2017 Texas Academy of Sciences annual meeting in Belton, Texas on March 4, 2017.

American Eel in Texas – what we do, don’t, and need to, know

Copy of the oral presentation made by the first author to the January 2016 meeting of the Texas Chapter of American Fisheries Society in Kerrville, Texas. Presentation is provided in several file formats. Data mapped in the presentation are also included in kml format (Google Earth).

Apparent Persistence of a Landlocked Population of Gulf Pipefish, Syngnathus scovelli

Abstract Though adults and older juveniles of some species are commonly encountered in freshwater reaches of coastal streams and rivers, pipefishes in general are believed to be either amphidromous or marine. In 1992, Gulf pipefish (Syngnathus scovelli) were reported in Lake Texana, a reservoir on the Navidad River near Edna, Jackson County, Texas. In June 2011, we collected an adult male with embryos and a juvenile from the same lake. This strongly suggests reproduction and persistence of the population at Lake Texana, which does not have access to saline waters. Though presence of a viable, reproducing population was not absolutely confirmed this appears likely to be the first known landlocked, freshwater population of any species of pipefish. Resumen Aunque adultos y juveniles mayores de algunas especies se encuentran comúnmente en aguas dulces de arroyos y ríos costeros, en general se considera que las especies de pez pipa son anfídromas o marinas. En 1992, el pez pipa del Golfo (Syngnathus scovelli) fue reportado en el Lake Texana, una presa artificial sobre el río Navidad cerca al poblado de Edna, condado de Jackson, Texas. En junio de 2011, colectamos un macho adulto con embriones y un juvenil en el mismo lago, hecho que sugiere la reproducción y persistencia de la población del Lake Texana, el cual no tiene acceso a aguas salobres. Aunque no se ha confirmado absolutamente, parece muy probable que esta población represente la primera población de pez pipa que puede reproducirse en agua dulce sin tener salida a agua salobre.