In a new paper published in the research journal Scientific Reports, ‘Coral persistence despite marginal conditions in the Port of Miami‘, the monitoring of sites throughout the Port since 2018 revealed periodic extremes in temperature, seawater pH, and salinity, far in excess of what have been measured in most coral reef environments. Despite conditions that would kill many reef species, we have documented diverse coral communities growing on artificial substrates at these sites—reflecting remarkable tolerance to environmental stressors. Furthermore, many of the more prevalent species within these communities are now conspicuously absent or in low abundance on nearby reefs, owing to their susceptibility and exposure to stony coral tissue loss disease.
As we hypothesized in 2014 and evidenced by our recent findings, Miami’s system of urban waterways provides an inadvertent anthropogenic laboratory whose corals hold keys to understanding how the world’s coral reefs might adapt to changing climate and water chemistry in the decades to come.
As reported in the Miami New Times, in June 2022, a combination of heavy rains and an ancient crumbling seawall in the process of reinforcement along Star Island’s southwest corner resulted in its collapse. The collapse was discovered by our colleagues at NOAA who arrived there by boat to study the nature and resilience of the urban corals in North Biscayne Bay. This is in addition to sites on the north and south side of the MacArthur Causeway and the east end of PortMiami near the Coral City Camera. Brain corals from these sites were analyzed and published ‘Molecular Mechanisms of Coral Persistence Within Highly Urbanized Locations in PortMiami’ in 2021, the first paper of its kind to offer an explanation for the success of these corals compared to their offshore counterparts.
Coral Morphologic first began exploring these urban habitats after documenting an unusual Acropora sp. inside Government Cut in 2009 which totally upended the idea of what an ‘ideal’ habitat was for these endangered stony corals. We subsequently started exploring areas deeper in North Biscayne Bay and found surprisingly robust populations of reef building corals. When a historic cold snap in January 2010 left them unphased (while the Florida Keys nearshore corals were all but wiped out), we began to suspect that the corals in these habitats were truly special, and scientifically valuable for research.
Colin first observed the Star Island seawall on Feb 14th 2013 when Gloria Estefan’s son Nayib asked him to document the marine life living along their riprap seawall (she was so happy to learn how healthy it was!). He was amazed by the life on these rocks, and how many more fish there were around them then on the neighboring seawall that lacked riprap. But upon closer inspection there were several very large Orbicella faveolata encrusted directly on it and multiple large brain corals at the base of it. This seawall at 40 Star Island Drive was likely the oldest seawall in Miami, possibly dating back to its development in the 1920s.
When the SCTLD (Stony Coral Tissue Loss Disease) outbreak took off in 2015 we observed that these urban corals seemed to be more resistant to it, and would often survive with partial mortality. With these anecdotal observations, Dr. Ian Enochs of NOAA reached out to us about setting up a formal investigation to see how these corals might differ from their offshore counterparts.
In early 2020 with the launch of the Coral City Camera, the CURES (Coral Urban Research Experimental Site) nursery was set up within view at the east end of Port Miami where research continues to this day (and now serves as an experimental research site for Rescue a Reef to ‘stress adapt’ their corals to help find more resilient strains that will be useful in the restoration of Miami’s nearshore reefs).
After NOAA and the University of Miami performed the rescue of the corals at 40 Star Island in July, they repatriated a number of them to an offshore ‘Spawning Hub’ on Rainbow Reef where they will be able to spawn with other members of their species and hopefully provide some other their resilient genetics and microbiome to the next generation. Fifteen colonies and fragments of corals were also brought to the Coral City Camera site at PortMiami where they were cemented down by UM scientists. Several weeks later, all these transplanted corals have survived and appear to be settling in nicely to their new urban coral community.
Update 11/2/22: Watch a follow-up feature on the seawall collapse and coral rescue with ABC WPLG Local 10 anchor / reporter Louis Aguirre:
On June 23rd, 2021 fifteen colonies of five different genotypes of endangered staghorn corals (Acropora cervicornis) were transplanted to the rubble zone in front of the Coral City Camera by Rescue a Reef, a citizen science program based at the University of Miami. The goal of this experiment was to try and identify stress-tolerant strains of staghorn corals to better inform Rescue a Reef of the strains best suited for near-shore habitats. We anticipated that not all the strains would survive (or perhaps none would survive), but given that this was a science experiment using clones, any mortality would be offset by the fact that dozens to hundreds of more clones exist in Rescue a Reefs offshore coral nurseries. The results greatly exceeded our best expectations!
As far as we are aware, this is the longest continuous in-situ growth timelapse of corals ever made!
This timelapse begins on June 28, 2021, just a few days after transplantation and replacing the CCC (which slightly altered the perspective). Over the course of the next several weeks, tissue die-off progressed rapidly across many of the colonies (Seen as bright white skeleton before being overgrown with brown algae). However, after a month of acclimation, the staghorn corals stabilized and adapted to their new Anthropogenic habitat despite water temperatures exceeding 90 (32C) in August and September (but no significant coral bleaching was observed!). Over the course of this time, the perspective shifts slowly as the Camera slowly subsides in the sediment and leans away from the rubble zone (due to the powerful currents in the area).
Ongoing research with University of Miami, NOAA, and Penn State University is now looking into the microbiomes of these staghorn corals to compare how they may have changed from their offshore clones. We observed on a night dive in September of 2021 while filming the ‘Coral City Fluorotour‘ that these staghorn corals were expressing fluorescent green proteins which is unusual for the species, and isn’t observed in their offshore counterparts. Unlocking the secrets of these urban-adapted ‘super corals’ is just the next step in understanding their remarkable resilience. Perhaps the site around PortMiami is ideal for evolutionarily assisting and stress-adapting corals before out-planting to the beleaguered nearshore reefs around Miami.
Just as the new coral growth is interesting to watch, equally interesting is to witness the erosion and disappearance of the dead staghorn branches of the colony closest to the Camera. This erosion occurs from the parrotfish whose powerful beak-like teeth can rasp the surface layer of algae while crunching the limestone skeleton (and then pooping sand). The club-tipped finger coral (Porites porites) in the lower right corner of the view is also interesting to observe over the year, as the parrotfish are fond of eating the healthy branch tips, rendering them very club-like in Coral City!
Playback speed is at 15 frames (days) per second (about one month per 2 seconds).
Symmetrical Brain Coral (Pseuododiploria strigosa) emersed during low tide along the shoreline of PortMiami.
For more than a decade, Coral Morphologic has sought to shine a spotlight on Miami’s intertidal urban corals and their potential scientific value. These surprisingly resilient corals appear to avoid bleaching and stem disease better than their conspecifics offshore on the natural reefs. Over the past two years we have been working with scientists at NOAA’s Atlantic Oceanographic Meteorological Laboratory (AOML) to explain these differences using molecular lab analysis of tissue samples collected in the field. That work finally culminated in ‘Molecular Mechanisms of Coral Persistence Within Highly Urbanized Locations in the Port of Miami, Florida‘ published in the research journal Frontiers in Marine Science.
We found that the Symmetrical Brain Corals (Pseuododiploria strigosa) living in the urban environment (specifically alongside MacArthur Causeway and Star Island in Miami) were predominantly colonized by the Durusdinium sp. strain of symbiotic algae (zooxanthellae) that provides the coral with photosynthetic energy during daylight hours. Durusdinium is known to be a heat-tolerant genus of zooxanthellae, and has long been investigated by scientists seeking to create bleaching-resistant ‘super corals’. However, until this study, the Symmetrical Brain Coral had rarely been observed hosting this species of zooxanthellae elsewhere in the region, making these observations here in Miami quite remarkable.
Beyond the helpful symbionts, the Symmetrical Brain Corals living in the urban environment were also found to be producing proteins and enzymes known to identify and digest pathogenic invaders. These proteins could be a two-fold benefit to the coral since disease-causing microbes can be digested as food before they can infect the coral. The urban marine environments around Miami often have high concentrations of phytoplankton and turbidity in the water, along with high bacterial concentrations that frequently require ‘no swim’ public health advisories. The ability to capture and extract more energy from food could enhance its health and provide sustenance during times of bleaching.
These findings from a single species of urban coral in Miami’s coastal environment suggest further investigation is warranted in the variety of other reef-building species that have self-recruited to the City’s concrete and riprap shorelines. It also demonstrates how the human-made hydrogeologic conditions around PortMiami serve as an evolutionary gauntlet selecting for corals better adapted for life in the Anthropocene.
On November 27th we embarked on the first field trip with researchers from NOAA and University of Miami for the next phase of Coral Morphologic’s long-term project to document, study, and conserve Miami’s unusually resilient ‘urban corals’. That is, the corals that have pioneered into Miami’s intercoastal waterways as larvae and settled onto man-made infrastructure. It is precisely Miami’s legacy of anthropogenic disturbance that led Coral Morphologic to recognize that the City was a real-world window in which to understand how corals may adapt and evolve to anthropogenic impacts.
Studying genetic variation and the underlying causes of these variations is at the heart of a global effort to identify more resilient coral genotypes capable of restoring degraded coral habitat. Most of this research has focused on traditionally healthy, offshore reef habitats and identifying corals that show more resilience to stress than neighbors, or in experimental lab settings with distinct coral colonies of the same species subjected to stressful conditions. However, our project proposes to sample the tissue of healthy coral colonies (specifically Pseudodiploria strigosa and Porites asteroides) living in less than ideal ‘urban’ conditions, as well as healthy coral living offshore in ‘natural’ conditions, to determine if the genetic variation between sites is significant. The sample sites will also be surveyed and scientifically described by community assessment and seasonal changes through photo mosaics, monitoring of water chemistry, temperature, pH, and light levels, to quantify and compare site conditions. The final phase of this project will involve transplanting corals to the tip of PortMiami from each of the ‘urban’ sites, along with fragments from the offshore, natural reef to compare how each is able to adapt, and eventually developing an ‘urban coral’ nursery to grow the most resilient coral genotypes for restoration of reefs and laboratory research.
But the first task in this year-long study was to characterize each of the study sites through photo-mosaics that create three dimensional maps using a pair of GoPro cameras. These maps will serve as our detailed baseline imagery to better understand the forces of coral recruitment, growth, mortality, competition from macroalgae, and the accumulation of trash/ debris over time. Watch the video above to see each of the three urban coral research sites and the techniques used to document them. We look forward to providing updates over the course of the year as we document the sites, analyze transcriptomes, transplant corals, and characterize range of water quality and chemical conditions that Miami’s urban corals endure.
Our good friend Akihiro Shiroza, a marine biologist at NOAA here in Miami, spends most of his working hours looking at the planktonic larvae of fish, corals, crustaceans, etc., under microscope. He was kind enough to share photos of some of the cool plankton he encounters. It appears here that he discovered a squid vs. shrimp battle of micro-mythological proportions. He used a polarizing filter to get the cool rainbow background effect. We’ll look forward to more of Aki’s photographic finds here in the future.
