Lots of cool stuff coming out of the lab right now – Summer has already been productive and we’re exploring new approaches to address our hypotheses. Earlier this year, in collaboration with scientists at UGA, UCSC, SFSU, and UNCW, we published the results of our 7-year investigation into the etiology of Sea Star Wasting Disease, which concluded that a likely culprit (or at least a plausible cause) of the condition was heightened microbial oxygen consumption at the animal-water interface. Following this, we presented work showing that the condition is a basal-to-surface (read: internally driven) pathology, which affects different color morphs in different ways. And very recently, Ian published a review summarizing evidence for low oxygen conditions based on oceanographic conditions and from host gene transcription. However, we have one piece of crucial, and missing, information, which also applies to our new work on sea cucumbers and seagrasses: How thick is the boundary layer on animal/plant surfaces, and can oxygen deplete sufficiently to cause damage?
For the last few weeks, Ian has been trying to fabricate and test planar “optodes” which are thin films of oxygen sensitive material that, when oxygen is low or absent, fluoresce under certain wavelengths of light. These have been in use in a variety of settings, including soils, marine sediments, etc – but we have never applied these to animal surfaces or seagrass blades. The original paper on their fabrication (Larsen et al., 2011) provided a truly exceptional, detailed protocol for how to make them – and in the decade since this publication materials have become widely available and super cheap. Unfortunately, Ian’s first attempts to fabricate the optodes were not successful (the thickness varied considerably from place to place on the surface, and it was difficult to see!). However, after some amazing advice from Anni Glud at the University of Southern Denmark, we finally had success today!
The image is of an optode deployed in an aquarium containing freshwater sediment from our campus pond (Huston Pond) and some water above. The low oxygen zone is really visible (red) compared to the oxic overlying water (blue-ish). This photo was taken with an iPhone, but for research use we have a SLR camera with emission filter which has even more dramatic images, and clearly show anoxia within the sediments and some in overlying waters.
Stay tuned for more cool images in coming weeks!