This is the live list of open questions from the analysis, aimed at the Tela Coral team and any researcher who wants to help. It doubles as a research agenda: each item says why it matters and what an answer would settle. The most valuable answers are in-water and on-the-ground, the things satellites and models cannot see. If you can help with any of these, please get in touch.
Our leading hypothesis is a first-flush-driven, localized low-oxygen (hypoxia) event, see The Science §7. These questions would confirm or refute it.
| Question | Why it matters |
|---|---|
| Was there a notable storm / heavy rain at Tela around June 5-6, 2023, right before the reef turned milky? | LARGELY ANSWERED Yes. Three airport stations (La Ceiba, Roatán, San Pedro Sula) independently recorded a thunderstorm sweeping the north coast the night of June 5-6, 2023, with a downburst cold-pool signature (see Methods). Station data confirms the storm and its convective character; the rain total still comes from gridded products plus the record-dry antecedent. A Tela rain gauge or a timestamped photo would close the last mile. |
| Was the reef impacted around March 2024? | TEST UNAVAILABLE We had ranked this the single most decisive question, because March 2024 was an even more extreme dry-season-break setup than June 2023. It cannot be answered. The monitoring programme reports that by March 2024 the reef was still largely dead from 2023 (pers. comm., Aug 2026), so a second mortality would leave no detectable signal against that baseline. Two further confounds: surveys run June to August only, so nothing brackets a March event, and 2024 carries the highest heat dose in our record (peak DHW 19.3, October) with a regionally documented mass bleaching at Tela, so any 2024 mortality has a simpler explanation than a March storm. This closes our main falsification route rather than confirming the hypothesis. |
| Was there an earlier full-bleaching event at Tela in 2019, and when? | ANSWERED Yes, and it was November 2019, not the early summer we first asked about. We raised this question earlier the same day on the possibility of a June or July event, because mid-2019 carried no heat at all and no qualifying storm, which would have made it a second unexplained early-summer die-off. The date settles it the other way: November 2019 sits right on the year's heat peak (DHW 12.3 on 1 November, peak 13.0 on 25 October), so it is ordinary thermal bleaching and needs no special mechanism. Our recurrence idea is dead. Two things survive it, and both are more useful: the contrast with June 2023, which struck months before that year's heat peak, and a replacement natural experiment (see § below). |
| Status of the Max Planck coral cores (collected 2025), do they carry a sediment / low-oxygen / geochemical signal for June 2023? | The single most decisive in-situ evidence. Redox-sensitive trace elements and isotopes in the skeleton can record a past hypoxic pulse. |
| Do Christian Carias or Antal Börcsök have dated photos or video of the milky substance from the event? | No public image exists. A timestamped diver photo is the only realistic visual record; the event was subsurface and cloud-covered, so satellites can't supply it. This ask has become more urgent, not less. The milky layer rests on a single first-hand account; a second research group that works the same reef regards it as unverified and will not publish it. An image, or a second independent eyewitness, is what would move it from testimony to evidence. Local dive operators who were in the water that week are the most likely source. |
| Any water-quality, dissolved-oxygen, salinity, odor, or bacterial-mat observations from the event window? | Even qualitative notes (foul smell, white mats, murky sub-surface layer) would distinguish hypoxia/H₂S from other causes. |
Every satellite and reanalysis dataset we ran agrees on one thing: this event class lives below their resolution. Confirmation needs sensors in the water.
| Ask | Why it matters |
|---|---|
| Deploy in-situ dissolved-oxygen + CTD (salinity/temperature) loggers on the reef, ideally before the next dry-season-break storm. | Would directly catch a stratification + oxygen crash in the act. This is the concrete, fundable monitoring recommendation from the whole study. |
| Water chemistry at the river mouth and on-reef: alkalinity : DIC ratio, nutrients (N:P), and BOD (oxygen-demanding organic load), especially during a storm pulse. | Alkalinity:DIC tests the carbonate-subsidy idea; N:P and BOD test the first-flush / eutrophication pathway. |
| Question | Why it matters |
|---|---|
| The XRF composition data for the black sand (titanium, iron, manganese). | ANSWERED Received (6 scans, 2 sites). Confirmed a heavy-mineral placer sand (~23% Ti, ~1.6% Mn, ~0.5% Cr, Th/U), with iron site-split (bay ~4%, lagoon ~0%). It drove the redox model in §8. Open follow-on: a benchtop leach assay (oxygen-rich vs oxygen-poor) to measure the actual manganese release rate. |
| Symbiont typing, is heat-tolerant Durusdinium dominant across the bay's corals? | The one resilience mechanism we can't compute; a documented cause of not-bleaching. (Baker lab work, unpublished.) |
| Status of the coral-pathogen + black-sand culture experiments (North Carolina). | Tests the TiO₂-photocatalytic-antiseptic idea directly. |
| Manganese as a coral treatment, dose and particle-size trials for the bio-bank. | IN PROGRESS The benefit literature, dose window, and Honduras slow-dissolve sourcing are now compiled (§11); low-dose Mn protects heat-stressed corals and the (iron-free lagoon) sand delivers it naturally. The field / bio-bank dose and particle-size trials are still open. |
| Data / contact | Why it matters |
|---|---|
| Operation Wallacea Tela/Banco Capiro benthic + Diadema time series (2011-2024). | The long record needed to fit the herbivory / recovery-vulnerability model to real magnitudes. |
| UT Austin metabolomics / genetics of the rare corals, status and PI contact. | Directly fills the symbiont/biochemistry gap and is a co-authorship path. |
| Juan Carlos & Karolina (Univ. Cádiz) nutrient survey data. | The nearest real nutrient measurements for the bay; no in-situ nutrient time series exists otherwise. |
| A 3-year bay oceanographic time series (the shared goal). | Would turn every hypothesis here into a testable, fitted model. |
This list is maintained alongside the analysis. Methods and datasets behind these questions are on the Methods & Data page; the findings are in The Science. Nothing here is a settled result, these are the open ends, stated plainly so others can pick them up.