Evaluation of Indoor and Outdoor Aquaculture Systems as Alternatives to Harvesting Hemolymph From Random Wild Capture of Horseshoe Crabs

Rachel Tinker-Kulberg,Lisa C Gentit,Lee Robertson,Lance Tōland,Cole A Wilder,Christopher L Kepley,Anthony L Dellinger,David J Stasek,Bryan A Fluech,Terry E Brady,Ivy L Spratling,Melinda K Goddard,Kristen Dellinger

doi:10.3389/fmars.2020.568628

Abstract

This study evaluated two approaches to the aquaculture of L. polyphemus with the ultimate goal of harvesting LAL at an industrial scale. To monitor HSCs, a combination of physical, biochemical and cellular components were examined for HSC cohorts in an indoor recirculating aquaculture system (RAS) and an outdoor on-bottom pen culture system (PCS) over a 6-month period. The metrics included body weight, hemocyanin (Hc) concentration, amebocyte density, and LAL reactivity. In addition, a simulated biomedical bleeding event (extracting 30% of the total hemolymph volume) was performed to assess physiochemical properties of the hemolymph and amebocytes after a one-week recovery period. Overall, the HSCs fared better in the RAS compared to the PCS, with higher rebound kinetics with respect to Hc concentrations, amebocyte density, LAL reactivity, and with 100% survival in the RAS cohort. Further, hemolymph reinfusion (after amebocyte removal) was shown to improve HSC recovery time. In summary, outcomes of this research show that a RAS, coupled with adequate nutrition and care can provide HSCs with a suitable environment for sustainable hemolymph extraction and year-round LAL production.

Highlights

The horseshoe crab (HSC) belongs to the order of arthropods, xiphosurans, dating back to the Ordovician period and are believed to be morphologically unchanged for some 148 million years (Rudkin and Young, 2009; Blazejowski, 2015; Manca et al, 2016; Akbar-John et al, 2018; Bicknell and Pates, 2020)
In the indoor recirculating aquaculture system (RAS), water temperature varied between 17.1–21.7◦C and Dissolved oxygen (DO) between 6.3–11.1 mgL−1 across all tank systems using supplemental aeration, without discernable trends appearing over time (Figures 3A,C)
The temperature in the outdoor system increased steadily (∼15◦C) over the course of the study due to seasonal fluctuations and the DO varied between 3.7–7.6 mgL−1, with a subtle, yet concurrent, decrease over time (Figures 3C,D)

Summary

Introduction

The horseshoe crab (HSC) belongs to the order of arthropods, xiphosurans, dating back to the Ordovician period and are believed to be morphologically unchanged for some 148 million years (Rudkin and Young, 2009; Blazejowski, 2015; Manca et al, 2016; Akbar-John et al, 2018; Bicknell and Pates, 2020). When combined with demand for HSCs as whelk and eel fishing bait, as well as climate change and consequent habitat erosion threatening numerous migrating shorebird species, compounded by corresponding threats to Asian HSCs, alternative strategies to ensure sustainable supplies of LAL are increasingly vital Notwithstanding their distinction as “living fossils,” HSCs are of interest to the medical device and pharmaceutical industries given the importance of their blood (hemolymph), which contains a specialized cell, or amebocyte (Mürer et al, 1975; Van Holde and Miller, 1995; Rudkin et al, 2008). This immediate response to LPS and subsequent gel-clot formation has been employed in an assay using LAL, which has been considered the gold standard for quality assurance against pyrogens in the pharmaceutical and medical device industry since the 1970’s (Mikkelsen, 1988)

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Conclusion