Transcriptome responses in copepods Calanus finmarchicus, Calanus glacialis and Calanus hyperboreus exposed to phenanthrene and benzo[a]pyrene

Effects of petrogenic pollutants on North Atlantic and Arctic Calanus copepods: From molecular mechanisms to population impacts

Oil and gas industries in the Northern Atlantic Ocean have gradually moved closer to the Arctic areas, a process expected to be further facilitated by sea ice withdrawal caused by global warming. Copepods of the genus Calanus hold a key position in these cold-water food webs, providing an important energetic link between primary production and higher trophic levels. Due to their ecological importance, there is a concern about how accidental oil spills and produced water discharges may impact cold-water copepods. In this review, we summarize the current knowledge of the toxicity of petroleum on North Atlantic and Arctic Calanus copepods. We also review how recent development of high-quality transcriptomes from RNA-sequencing of copepods have identified genes regulating key biological processes, like molting, diapause and reproduction in Calanus copepods, to suggest linkages between exposure, molecular mechanisms and effects on higher levels of biological organization. We found that the available ecotoxicity threshold data for these copepods provide valuable information about their sensitivity to acute petrogenic exposures; however, there is still insufficient knowledge regarding underlying mechanisms of toxicity and the potential for long-term implications of relevance for copepod ecology and phenology. Copepod transcriptomics has expanded our understanding of how key biological processes are regulated in cold-water copepods. These advances can improve our understanding of how pollutants affect biological processes, and thus provide the basis for new knowledge frameworks spanning the effect continuum from molecular initiating events to adverse effects of regulatory relevance. Such efforts, guided by concepts such as adverse outcome pathways (AOPs), enable standardized and transparent characterization and evaluation of knowledge and identifies research gaps and priorities. This review suggests enhancing mechanistic understanding of exposure-effect relationships to better understand and link biomarker responses to adverse effects to improve risk assessments assessing ecological effects of pollutant mixtures, like crude oil, in Arctic areas.

Persistent organic pollutants (POPs) in marine crustaceans: Bioaccumulation, physiological and cellular responses

Persistent organic pollutants (POPs) are ubiquitous in marine ecosystems. These compounds can be accumulated in water, sediments and organisms, persist in time, and have toxic effects in human and wildlife. POPs can be uptaken and bioaccumulated by crustaceans, affecting different physiological processes, including energy metabolism, immunity, osmoregulation, excretion, growth, and reproduction. Nonetheless, animals have evolved sub-cellular mechanisms for detoxification and protection from chemical stress. POPs induce the activity of enzymes involved in xenobiotic metabolism and antioxidant systems, that in vertebrates are importantly regulated at gene expression (transcriptional) level. However, the activation and control of these enzyme systems upon the exposure to POPs have been scarcely studied in invertebrate species, including crustaceans. Herein, we summarize various aspects of the bioaccumulation of POPs in marine crustaceans and their physiological effects. We specially focus on the regulation of xenobiotics metabolism and antioxidant enzymes as key sub-cellular mechanisms for detoxification and protection from chemical stress.

Data on SSR markers and SNPs filtered from transcriptome of Parvocalanus crassirostris

Calanoid copepod populations are being severely affected due to the effects of ocean acidification (OA) and ocean warming (OW). These marine organisms are the most abundant primary consumers contributing significantly in the marine food web. Any effect on the abundance and diversity of copepods due to climate change is likely to have serious implications on the marine ecosystem functioning. Molecular studies that play a vital role in assessing the genetic changes under the influence of environmental imbalances are completely lacking for this species. Here we report the genetic variations in three generations of copepods through transcriptome sequencing. RNA sequencing was performed on an Illumina HiSeq platform employing the 2 × 100 bp paired-end chemistry. Approximately, 10GB of data was obtained for all the samples. The raw sequences were assembled through Trinity 2.6.6 and mined for single nucleotide polymorphisms (SNPs) and simple sequence repeats (SSRs). MIcroSAtellite Identification Tool (MISA) was used for SSR detection and Primer 3 (v 3.0) was utilized to design short oligonucleotide primers (18-20 mers). A total of 15,222 SSRs were identified and 28,944 primer pairs were designed against these motifs. The transcriptome possessed 413,890 SNPs at a frequency of 2.8 per kb. The newly discovered SSRs and SNPs could act as genetic markers for future studies on genetic diversity and conservation for Parvocalanus crassirostris.