New Preprint on Sea Star Wasting – It’s all about the Boundary Layer

After many years of concerted investigation, the team and some colleagues now have multiple, convergent lines of evidence to suggest that sea star wasting disease is a sequela of organic matter remineralization (and subsequent hypoxic conditions) in the boundary layer overlying respiratory surfaces. We see this reflected in microbiome trends during wasting (copiotrophs –> anaerobes). We also observe no viruses consistently associated with wasting during progression, reinforcing our previous work (Hewson et al., 2018) that viruses are not associated with sea star wasting disease, despite our initial work (Hewson et al., 2014). Indeed, we now feel that experiments run in 2014 in which tissue homogenates were injected into asymtpomatic individuals (which were the only 2 successful experiments among 5 at the time, and we have failed to repeat in a further 4 trials since), were flawed in the sense that homogenates also bore high concentrations of organic matter which may have fuelled this exact same effect. The impact of this condition would be most pronounced in larger animals, those which are more corrugated (we show this through computed tomography), and more active species. Wasting on a seasonal basis follows phytoplankton blooms at one site where chlorophyll a and sea star wasting were measured together. Looking back at samples from 2013 -2014, we found evidence of dissimilarity nitrogen processing (which occurs under anaerobic conditions) in stable isotopic ratios in tissues.  You can check out the preprint here:

https://www.biorxiv.org/content/10.1101/2020.07.31.231365v1

It is a long read, and it describes many studies. But please bear with it – any one of those studies in isolation would not provide the full picture. It is only on aggregate that the mechanism of wasting – at least what we have evidence for – becomes clear. Incidentally, these results are fully compatible with several studies which have come out in the last 5 years examining temperature variation and its relation to wasting. Under warmer conditions, boundary layers will become more O2-depleted, for example.

As this is a preprint, it should be viewed as non-peer reviewed, and should not guide treatment or practice.

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