Comparative metatranscriptomics reveals decline of a neustonic planktonic population

Abstract

The neuston layer in tropical seas provides a good model to study the effects of increased levels of different stressors (e.g., temperature, ultraviolet radiation and Trichodesmium blooms). Here, we use a comparative in situ metatranscriptomics approach to reveal the functional genomic composition of metabolically active neustonic mesozooplankton community in response to the summer conditions in the Red Sea. The neustonic population exhibited changes in composition and abundance with a significant decline in copepods and appendicularia in July, when Trichodesmium cells were more abundant along with high temperatures and UV‐B radiation. Nearly 23,000 genes were differentially expressed at the community level when the metatranscriptomes of the neustonic zooplankton were compared in April, July, and October. On a wider Phylum level, the genes related to oxidative phosphorylation, carbon, nucleotides, amino acids, and lipids were significantly overrepresented in both arthropods and chordates in April and October. On organism level for copepods, expression of genes responsive to oxidative stress, defense against bacteria, immune response, and virus reproduction were increased along with the observed increased appearance of copepod carcasses in the samples collected during July. The differences in expression correspond either to secondary effects of the Trichodesmium bloom or more likely to the increased UV‐B radiation in July. Given the dearth of information on the zooplankton gene expression in response to environmental stimuli, our study provides the first transcriptome landscape of the mesozooplankton community during a period of increased mortality of the copepod and appendicularia population.

Blue pigmentation of neustonic copepods benefits exploitation of a prey-rich niche at the air-sea boundary

“…S6 ) and no enhanced mortality, i.e. increased numbers of carcasses could be observed in our samples being in contrast to other recent findings 30 . Apart from surface avoidance behavior, a typical response of copepods to UV stress 31 , and possessing sun screening carotenoids such as astaxanthin, emerging work has shown that UV-protective mycosporine-like amino acids (MAA) have an important role in UV protection of near-surface (top 50 cm) zooplankton communities 32 .…”

Physiological acclimatization in high‐latitude zooplankton

“…Environmental transcriptomics of planktonic organisms has contributed new insights into niche separation and led to new hypotheses to explain rapid changes in abundances (Alexander et al, 2015; Mojib et al, 2017). Neocalanus flemingeri is well suited for environmental transcriptomics: it has a single generation per year with an annual phenology that is predictable and synchronized with the annual spring phytoplankton bloom (Cooney, 1986; Cooney et al, 2001; Coyle et al, 2019; Coyle & Pinchuk, 2003).…”

The Virioneuston: A Review on Viral–Bacterial Associations at Air–Water Interfaces

“…In addition, viruses were found attached to mesozooplankton, e.g., collected from the neuston of the Red Sea using a Manta neuston net that sampled the top 1 m of the water column [ 92 ]. Due to observed high mortality of copepods (phylum Arthropoda) in their samples, the authors were looking for VLPs on Acartia fossae, a blue-pigmented surface-dwelling copepod, and its prey, Trichodesmium cells.…”