Assessing Occurrence and Biological Consequences of Contaminants of Emerging Concern on Oceanic Islands

Kelly M Diamond,Alexander M Rubin,Troy S Sakihara,Tonya C Schoenfuss,Heiko L Schoenfuss,Richard W Blob,Christopher J Good,Paul L Edmiston,Jennifer A Faust,Nina Johnny

doi:10.3390/w14030275

Abstract

Freshwater streams on oceanic islands serve critical ecological and economic functions. However, these are underrepresented in assessments of pollution from contaminants of emerging concern (CEC). Furthermore, freshwater streams and their endemic fauna often have characteristics that are distinct from those of continental streams and model species, calling extrapolations from studies of such systems into question for island streams. In the current study, we assessed the presence of CEC across three sampling events and five freshwater streams on the Island of Hawai’i. We also exposed juveniles of the native fish species Sicyopterus stimpsoni to a mixture of commonly co-occurring CEC for 96 h in static renewal experiments, testing for impacts of CEC in two ecologically relevant assays of functional performance. CEC from multiple sources were ubiquitous in Hawaiian streams, including human-use pharmaceuticals, agricultural herbicides, and industrial runoff. Concentrations of CEC were comparable to published studies from continental streams, exceeding total concentrations of 1000 ng/L for the eight quantified CEC in four samples, and approaching 2500 ng/L in one sample. Effects on exposed fish were subtle and limited to treatments with higher CEC concentrations but indicated potential impacts of CEC on locomotor performance. These results indicate that Hawaiian streams follow a global trend of widespread freshwater pollution by CEC that are accompanied by subtle effects on native fish species and highlight the need for the inclusion of endemic species and ecologically relevant assays when assessing the effects of contaminants in island habitats.

Highlights

The vast marine riches that surround oceanic islands frequently overshadow the paucity of fresh waters in these settings
As there were no data on contaminants of emerging concern (CEC) occurrence in Hawaiian streams available at the time of the exposure experiments, we developed a CEC mixture consisting of 14 compounds (Table 1) commonly present in many aquatic environments impacted by anthropogenic activity ([15,16]; reviewed in [17]), and because land use on the Hamakua Coast suggests their presence is likely [2]
Freshwater streams on the Island of Hawai‘i contain mixtures of CEC similar in composition and concentrations to freshwaters in continental streams

Summary

Introduction

The vast marine riches that surround oceanic islands frequently overshadow the paucity of fresh waters in these settings. Especially during the spring rainy season, can transport organic matter, pathogenic bacteria [3], and anthropogenic compounds such as pharmaceuticals, pesticides, and other industrial and personal care products off the landscape, through streams and estuaries, and into the ocean [4]. Many of these compounds represent contaminants of emerging concern (CEC), a grouping of chemicals loosely defined as either being introduced to the environments in the past few decades, recently discovered in the environment, or having newly discovered toxicological properties that have not been evaluated previously. The potential impacts of these CEC on the freshwater biota of islands like Hawai’i are not well understood, as few studies have focused on these distinct environments (e.g., [6])

Methods

Results

Discussion

Conclusion