Primary tabs

University of Michigan Biological Station

The University of Michigan Biological Station (UMBS) was founded in 1909.

Social

Behavioral responses to and bioindicator potential for PFASs exposure in crayfish species

Aquatic
Project Abstract: 
Due to the continued anthropogenic degradation of environments, there is an increased necessity for bioindicator species to aid in the assessment of impacts on aquatic ecosystems. Several characteristics of crayfish offer them as a suitable candidate as a bioindicator: global distribution, high population densities, low migratory rate, sensitive physiology and behaviors, and easy maintenance within laboratory environments. The demonstrated applicability of crayfish as a biomonitor for an array of well-studied anthropogenic toxicants and their role as an important keystone species, raises interest in their sensitivity to and the application of crayfish as a bioindicator for emerging contaminants such as per- and poly-fluorinated alky substances (PFAS). The perflourinated compounds, perfluorooctyl sulfonate (PFOS) and perfluorooctanoic acid (PFOA), have gained particular research focus due their widespread detection and stability within the environment. Previous research has demonstrated exposure to PFAS causes negative effects on the reproductive, endocrine, immune and nervous systems of experimental organisms, however, behavioral effects have not been well documented. The aim of this study is to investigate the behavioral implications of PFAS exposure on crayfish species and the validity of using these organisms as bioindicator model for PFAS contamination. Differences in the escape response of crayfish from the predatory odor of Micropterus salmoides and in plant consumption will be compared between animals collected from various polluted locations in Northern Michigan. Water chemistry sampling in Northern Michigan environments performed by Tip of Mitt Watershed Council (Petoskey, Michigan) and University Michigan Biological Station Analytical Laboratory (Pellston, Michigan) will provide verification of PFAS concentrations at crayfish sampling sites to determine the relationship between behavioral deficits and toxicant concentration. Due to the prevalence and known uptake of perfluorinated compounds by aquatic organisms, a suitable bioindicator species and further study on important fitness related behaviors that may be affected by PFAS are critical.
Investigator(s): 
Paul Moore
Alexandra Nicole Steele
Years Active: 
2019
Methods: 
The aim of this study is to investigate the behavioral effects of PFAS on crayfish species. Differences in the proportion of crayfish expressing bold and shy personalities and in plant consumption as a result of differing concentrations of PFAS exposure will be compared between animals collected from various locations in Northern Michigan. Animals will be collected using minnow traps baited with sardines contained in mesh bags. Traps will be placed at sites that correlate with water chemistry sampling locations designated by Tip of the Mitt Watershed Council and Carrie Coy of the LSE. All animals used will have intact appendages and be used only once throughout the experiment. Crayfish will be isolated in plastic containers (15 x 10 x 10 cm) placed within artificial streams constructed of cinder blocks (20.3 x 20.3 x 40.6 cm) and 4 mil polyethylene sheeting at the University of Michigan Biological Station Stream Research facility, Pellston, Michigan prior to behavioral testing. Water entering the holding streams will be pumped from the East Branch of the Maple River and crayfish will be allowed to feed on naturally occurring detritus. Number of days spent within holding stream will be recorded. After field collection, crayfish responses to predatory chemical stimuli will be evaluated. Anti-predatory behavior exhibited by crayfish is dependent on multiple sensory modalities, however, is largely dependent upon olfactory cues (Clark and Moore, 2018; Hazlett, 2003; Shave et al., 1994). To evaluate the impairment of crayfish due to exposure, an olfactory dependent behavioral assay will be utilized. For this assay, each crayfish will be placed in an escape arena consisting of a trial box (13.5 x 7.5 x 8.5 cm; L x W x H) placed within a 3.8 L aquarium (51 x 26 x 30.5 cm; L x W x H) (Steele and Moore, 2019). The trial box will be constructed of opaque Plexiglas and equipped with one retractable wall and a stimulus source. Each aquarium will be filled to a depth of 10 cm with unfiltered river water from the East Branch of the Maple River. The exterior of each aquarium will be wrapped in black canvas to visually isolate each crayfish from the external environment. After a 120 second acclimation period, the retractable wall will be removed allotting each crayfish the option to exit the escape arena for a total of 600 seconds. As the retractable wall is removed, 25 ml of the stimulus will be administered to the escape arena near the wall opposite to the exit. The stimulus will consist of odor from the crayfish predator, Micropterus salmoides (largemouth bass) (Crowl, 1989; Jurcak and Moore, 2018). An observer blind to treatment will quantify latency to exit the trial box. Latency to leave the trial box will be recorded using a Sony handheld camera (model # HDR-CX405) and will be calculated as the time from release of stimulus to time that the carapace-tail joint of the crayfish is outside of the trial box entrance. To assess foraging behavior, an artificial stream system consisting of eight flow-through streams (40.6 × 40.6 × 40.6 cm, interior L x W x H) will be constructed using cinder blocks and 4 mil polyethylene sheeting. Water from the East Branch of the Maple River (Pellston, Michigan) will be pumped into head tanks placed at the upstream end of the artificial stream system. Water entering head tanks will be minimally filtered using nylon mesh to inhibit large debris from impacting flow into streams. Each stream will have a sand substrate of a depth of approximately 3 cm. Outflow blocks (40.6 x 20.3 x 20.3 cm; L x W x H) will be placed at the downstream end of the artificial streams to manipulate volume of water exiting the streams, and therefore water depth. Individual crayfish will be placed within in an artificial stream for a total of 23 hours and allowed to forage on provided plant species. Macrophytes of Chara spp. will be attached to glass stir rods (25 x 0.6 cm) using floral wire. Three stir rods with macrophytes attached will be placed in a hardware cloth bracket (24 x 19 cm) (Wood et al. 2018). One bracket will be placed in each artificial stream allowing crayfish to consume the macrophytes. Macrophytes mass will be recorded before and after placement in artificial stream to determine mass consumed by crayfish. Proportion of plant material consumed will analyzed to determine the effect of PFAS exposure concentration on foraging behavior of crayfish.