Reuben R. Goforth

Aquatic ecosystem protection and restoration: advances in methods for assessment and evaluation

Abstract Many methods and criteria are available to assess aquatic ecosystems, and this review focuses on a set that demonstrates advancements from community analyses to methods spanning large spatial and temporal scales. Basic methods have been extended by incorporating taxa sensitivity to different forms of stress, adding measures linked to system function, synthesizing multiple faunal groups, integrating biological and physical attributes, spanning large spatial scales, and enabling simulations through time. These tools can be customized to meet the needs of a particular assessment and ecosystem. Two case studies are presented to show how new methods were applied at the ecosystem scale for achieving practical management goals. One case used an assessment of biotic structure to demonstrate how enhanced river flows can improve habitat conditions and restore a diverse fish fauna reflective of a healthy riverine ecosystem. In the second case, multitaxonomic integrity indicators were successful in distinguishing lake ecosystems that were disturbed, healthy, and in the process of restoration. Most methods strive to address the concept of biological integrity and assessment effectiveness often can be impeded by the lack of more specific ecosystem management objectives. Scientific and policy explorations are needed to define new ways for designating a healthy system so as to allow specification of precise quality criteria that will promote further development of ecosystem analysis tools.

Sexually dimorphic gene expression in the gonad and liver of shovelnose sturgeon (Scaphirhynchus platorynchus)

The development of a biomarker for rapid detection of intersex is desirable to researchers and fisheries managers alike. The first step is to identify a marker that has a dimorphic expression pattern. With a focus on sex-specific genes, we assessed the use of vitellogenin (vtg), forkhead box L2 (foxl2) and doublesex and mab-3-related transcription factor 1 (dmrt1) as molecular biomarkers for the identification of gender in shovelnose sturgeon (Scaphirhynchus platorynchus), a species known to have intersex individuals. A total of 61 shovelnose sturgeons were sampled from the Wabash River, Indiana, in April 2008. Results from our study indicate that least 7.5% of the non-females had testicular oocytes. Expression level of liver vtg was not higher in females than males, nor was gonad dmrt1 expression found to be higher in males. Only the expression of foxl2 was significantly greater in females and was found to be useful for identifying gender. Variation in expression levels of foxl2 in gonads of intersex fish limited its usefulness as a single biomarker for identifying this condition. Instead, the use of foxl2 to dmrt1 (foxl2 transcript abundance/dmrt1 transcript abundance) may be useful in the identification of intersex fish, as this ratio increased with increased feminization. We conclude that foxl2 can be used to identify sex, but not intersex sturgeon.

Assessing impacts of land-applied manure from concentrated animal feeding operations on fish populations and communities.

Concentrated animal feeding operation (CAFO) manure is a cost-effective fertilizer. In the Midwest, networks of subsurface tile-drains expedite transport of animal hormones and nutrients from land-applied CAFO manure to adjacent waterways. The objective of this study was to evaluate impacts of land-applied CAFO manure on fish populations and communities. Water chemistry including hormone, pesticide, and nutrient concentrations was characterized from study sites along with fish assemblage structure, growth, and endocrine disruption assessed in selected fish species. Although most CAFO water samples had hormone concentrations <1 ng/L, equivalent concentrations for 17β-E2 and 17α-TB peaked at >30 ng/L each during the period of spawning, hatching, and development for resident fishes. CAFO sites had lower fish species richness, and fishes exhibited faster somatic growth and lower reproductive condition compared to individuals from the reference site. Fathead minnows (Pimephales promelas) exposed to CAFO ditchwater during early developmental stages exhibited significantly skewed sex ratios toward males. Maximum observed hormone concentrations were well above the lowest observable effect concentrations for these hormones; however, complexities at the field scale make it difficult to directly relate hormone concentration and impacts on fish. Complicating factors include the consistent presence of pesticides and nutrients, and the difference in temperature and stream architecture of the CAFO-impacted ditches compared to the reference site (e.g., channelization, bottom substrate, shallow pools, and riparian cover).

Spatial and seasonal variation in the ecological significance of nutrient recycling by larval salamanders in Appalachian headwater streams

Abstract. Salamanders are abundant consumers in many temperate streams and may be important recyclers of biologically essential nutrients, but their ecological role is poorly understood. The ecological significance of nutrient recycling by salamanders may vary spatially and seasonally because of their potentially patchy distribution in streams and the dynamic nature of stream hydrology and other nutrient fluxes. We examined the spatial and seasonal variation of salamander-driven nutrient recycling in 3 headwater streams in the southern Appalachian Mountains. We quantified the aggregate areal excretion rates of N (NH4+-N) for the larvae of the 2 most abundant salamander species in these steams before and after leaf fall to examine spatial and seasonal variation in the supply of nutrients from salamanders. We used short-term nutrient additions in each stream to examine temporal heterogeneity in the ecosystem demand for NH4+-N. Before leaf fall, salamanders were capable of meeting ∼10% of the ecosystem demand for NH4+-N and could turn over the ambient nutrient pool in ∼3 km. The significance of this contribution declined to ∼3% after leaf fall and the turnover length increased 7×. The ecological significance of salamander nutrient excretion varied by as much as 17× within streams and was as high as 30% of the nutrient demand in some stream sections, a result suggesting that salamanders may create biogeochemical hotspots in these nutrient-limited ecosystems. Thus, salamanders appear to be capable of contributing substantially to stream nutrient cycles through the excretion of limiting nutrients and may be underappreciated members of headwater stream ecosystems, particularly at small spatial scales. However, this contribution varied substantially seasonally and spatially.

Detecting the movement and spawning activity of bigheaded carps with environmental DNA

Bigheaded carps are invasive fishes threatening to invade the Great Lakes basin and establish spawning populations, and have been monitored using environmental DNA (eDNA). Not only does eDNA hold potential for detecting the presence of species, but may also allow for quantitative comparisons like relative abundance of species across time or space. We examined the relationships among bigheaded carp movement, hydrography, spawning and eDNA on the Wabash River, IN, USA. We found positive relationships between eDNA and movement and eDNA and hydrography. We did not find a relationship between eDNA and spawning activity in the form of drifting eggs. Our first finding demonstrates how eDNA may be used to monitor species abundance, whereas our second finding illustrates the need for additional research into eDNA methodologies. Current applications of eDNA are widespread, but the relatively new technology requires further refinement.

Invasive Silver Carp movement patterns in the predominantly free-flowing Wabash River (Indiana, USA)

Many organisms must move among habitats to fulfill life history requirements. Fish movements have been widely studied and tend to be either fine-scale (i.e., routine) and governed by factors such as food availability and cover, or broad-scale and associated with spawning migrations. However, movements of invasive fishes in non-native ecosystems are comparatively poorly understood despite the often critical importance of fish movement and dispersal for invasion success. We examined invasive Silver Carp (Hypophthalmichthys molitrix) movements using acoustic telemetry to monitor the timing, distance, and direction of fish movements and assessed movements in relation to seasonal, annual, environmental, and individual factors in the Wabash River (Indiana, USA), a largely unregulated Midwestern river. Silver Carp exhibited highly variable movements that could be rapid and large in magnitude; however, tagged individuals remained stationary most of the time. Despite high variability, several trends emerged, indicating the importance of backwater habitats, avoidance of small tributaries, and tendencies of tagged fish to exhibit directed spring and fall broad-scale movements. Summer movements were smaller in magnitude, characterized by lower movement rates, and evenly split between upstream and downstream directions, although tagged Silver Carp moved more frequently during summer months. Our results indicate that specific seasons (i.e., spring and early fall) and locations (i.e., backwaters) are likely targets for Silver Carp control in the Wabash River and should also be useful targets for early detection and control in other largely unconstrained rivers over a broad geographic range (e.g., Great Lakes tributaries and upper Mississippi River mainstem and tributaries).

Antagonists to the Wnt Cascade Exhibit Sex-Specific Expression in Gonads of Sexually Mature Shovelnose Sturgeon

Little is known regarding molecular mechanisms involved in sex determination and differentiation in sturgeon species. We addressed this knowledge gap by using next generation pyrosequencing technology to provide transcript libraries and species-specific sequences for mature gonads of shovelnose sturgeon, Scaphirhynchus platorynchus. We then mined these libraries to identify gender-specific transcripts and quantified relative transcript abundance using quantitative real-time polymerase chain reaction (qPCR). We detected a limited number of genes known to play a role in sex differentiation in other species. The sequence for dmrt1 was found only in the testes library. The abundance of dmrt1 differed slightly between the sexes, but the melt curve suggests that there may be different isoforms of dmrt1 in ovaries and testes of shovelnose sturgeon. The transcription factor foxl2 was 5.3-fold greater in ovaries than in testes. Two antagonists to the Wnt cascade, dickkopf-1 (dkk1) and dapper-1 (dact1), were found only in the ovary library. Results from qPCR indicated that dkk1 and dact1 were upregulated 1,819.1- and 207.5-fold, respectively, in ovaries compared with testes. These results suggest that antagonists to the Wnt cascade may play significant roles in sex differentiation and gonadal development in sturgeon and could serve as sex markers in this group of ancient fish.

Multiscale Relationships between Great Lakes Nearshore Fish Communities and Anthropogenic Shoreline Factors

ABSTRACT The multi-scale nature of streams, rivers, and inland lakes is well documented, although relationships between the ecology of Great Lakes nearshore areas and shoreline processes are generally poorly described. Given the high levels of development pressure currently exerted on Great Lakes shorelines, we sought to determine whether patterns exist between measures of shoreline development quantified at multiple spatial scales and adjacent fish community measures. We expected that fish measures for nearshore areas immediately adjacent to intact versus modified shorelines would differ as a result of the greater buffering capacity of the intact shorelines. Further, we expected anthropogenic shoreline factors to act cumulatively in combination with prevailing currents to influence fish communities in downdrift nearshore areas. Our results indicated that a few shallow water and nearshore fish community measures exhibited significant patterns that may be attributable to immediately adjacent shoreline characteristics. In addition, several fish measures were related to urban-residential land uses and shore structure numbers of updrift shoreline areas, suggesting that cumulative anthropogenic factors operating over larger spatial scales also influence local fish communities. Based on these results, we argue that there is critical need for multi-scale management strategies for shorelines that address the potential for both local and cumulative, larger-scale environmental impacts relative to local nearshore biota.

Assessing stream integrity based on interpretations of map-based riparian and subbasin properties

Ecosystems have become a primary focus for conservation efforts seeking to maintain native freshwater biodiversity. Inherent in lotic ecosystem studies is consideration of the influences that multiscale environmental properties have on the state of biological communities and ecological processes, herein referred to more generally as stream integrity. The Watershed Habitat Evaluation and Biotic Integrity Protocol (WHEBIP) was developed to provide rapid assessment of stream integrity for stream segments throughout watersheds based on riparian and subbasin features interpreted principally from aerial imagery and topographic maps. Protocol calibration was based on relationships between WHEBIP scores and aquatic community and aquatic habitat field data collected in the French Creek watershed, Chautauqua County, NY, USA. A test of the protocol in the Cussewago Creek watershed, Crawford and Erie Counties, PA, USA, indicated that the WHEBIP can be used as a generalized-stream integrity rapid-assessment tool, especially related to fish communities. However, the protocol’s ability to predict stream macroinvertebrate biological integrity measures was limited, emphasizing that it should be used primarily as a stratification tool to guide the classification of stream integrity within watersheds.

Survival of Shovelnose Sturgeon after Abdominally Invasive Endoscopic Evaluation

Abstract The development of effective and minimally invasive techniques to determine gender and gonad developmental stage is particularly important in performing accurate fisheries assessments for use in conservation and restoration. The initial and latent survival of shovelnose sturgeon Scaphirhynchus platorynchus was assessed after exposure to a modified endoscopic technique designed to collect that biological information. Rather than inserting the endoscope through the urogenital canal or directly into the body cavity, we inserted a threaded trocar through a ventral incision and used a low-pressure air supply attached to the trocar to gently insufflate the body cavity. The initial survival of both experimental and control shovelnose sturgeon was 100%. Latent survival was 100% and 90% for the experimental and control fish, respectively. Our study suggests that incision endoscopy coupled with insufflation of the body cavity through the use of a trocar and an air supply is a safe and effective way to dete...