Hellgrammite as a Non-Conventional Biomonitor for Surface Water and Environmental Health Assessment

Summary

This protocol describes the use of biomarkers for the early detection of deleterious impacts in aquatic ecosystems. The biomarkers are closely related to sentinel traits, and their changes aid in detecting early-warning damages.

Abstract

The larvae of dobsonflies from the genus Corydalus, commonly known as Hellgrammites, are characterized by their notable size, extensive range of occurrence, and extended period of immaturity, which can last up to one year. Hellgrammites are clearly known to exhibit sensitivity to pollution and habitat structure impacts. Given these unique features, using Corydalus texanus larvae is highly suitable as reliable biomonitoring agents to assess the ecological integrity of aquatic ecosystems. This protocol aims to provide the necessary tools for C. texanus assessment and demonstrate their efficacy through a case study. Research findings have practical implications, indicating that C. texanus larvae exhibit early-warning responses to mining pollution, bioaccumulating high amounts of heavy metals such as Zn, Fe, and Al. The presence or absence of C. texanus populations may serve as a helpful indicator for identifying potential issues related to ecosystem health. The unconventional approach has shown early warnings of pollution in mining-impacted sites, highlighting the need for timely action to protect the environment. Given their unique traits, the use of C. texanus larvae is highly suggested as a reliable non-conventional bioindicator.

Introduction

Hellgramites are insect larvae from the order Megaloptera (Latreille, 1802), named dobsonflies or fishflies in their adult stage. A low diversity but widespread characterizes this group of top predator insect larvae from aquatic ecosystems¹. Hellgramite species occur in well-defined biogeographic regions; therefore, it is relatively easy to identify species without a high taxonomic knowledge. Notably, the Corydalidae larvae possess the most prominent species from the Megaloptera order (20-90 mm body length)², making hellgramite visible to the naked eye.

Hellgrammites play a crucial role in aqu....

Protocol

Figure 1: Quick step-by-step guide on how to use the non-conventional biomonitor Corydalus texanus for implementation in aquatic ecosystems. Please click here to view a larger version of this figure.

Results

The results of the study reveal that heavy metals, specifically Aluminum (Al), Iron (Fe), and Zinc (Zn), have a detrimental impact on the environment, as evidenced by Figure 2. The detection of high levels of heavy metals in both tissue and water samples collected from all sites has led to an unfavorable outcome. Outliers were detected, with a Bioaccumulation Factor (BAF) of 600, notably in mining-intensive areas such as the Extoraz River (sites PB, EP, RQ, and BC shown in

Discussion

Although the use of C. texanus is optimal for evaluation, it is necessary to consider several aspects of its use and collection. Chosen study sites prove challenging, owing to several factors such as unfavorable weather conditions, geographical inaccessibility, high aridity levels, or insufficient security protocols in selected regions. Stated constraints and limitations can often present challenges when conducting fieldwork. When evaluating specific regions, particularly those in tropical streams, obtaining sam.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Analytical balance of 220 g	Ohaus	PR224/E	This balance is useful for weighing the extracted tissue from specimens.
Chest waders	LaCrosse	700152M	We recommend using waders for sample collection. Alternatively, you can also use boots with rubber hip boots for sampling.
Cutting board	True	TRUE915121	It is recommended to use white and plastic boards.
Forceps	DR Instruments	112	It is recommended to use a 12 pul forceps made of stainless steel.
Inductively Coupled Plasma-Optical Emission Spectroscopy System	Perkin Elmer	7300 DV	A device for quantifying heavy metals using spectroscopy.
Kick net	LaMotte	0021-P	An alternative method for making a kick net involves manually crafting one using a mesh with a thickness of 500 micrometers.
Liquid Nitrogen	NA	NA	NA
Liquid Nitrogen Dewar Static Cryogenic Container	BestEquip	DF0504	It is recommended to use an aluminum tank with canisters.
Mortar and Pestle Set	Cole-Parmer	EW-63100-54	This is a porcelain mortar and pestle used for grinding dry tissues.
Multiwave GO Plus	Anton Paar	C93IP001EN-E	Multiwave is a useful tool for digesting multiple samples.
Oven for drying	Fisher scientific	506G	An incubator oven, also known as a dry tissue oven, is essential for drying tissues at temperatures of at least 80°C.
Precision scalpel	Xcelite by Weller	037103-48768	It is recommended to use a scalpel made of aluminum.
Tissue Homogenizer (tearer)	Kopro	K110000	It is recommended to use a tissue tearer with a base. Some companies offer ultrasonic tearers, which may be the optimal choice.
Ultra-Low Temperature Chest Freezer	REVCO	CA89200-384	Many companies provide freezers, but it is recommended to choose one with a storage temperature of at least -40°C.
Wide mouth plastic bottles	United Scientific	81900	Using polypropylene bottles with wide caps and mouths is strongly recommended.