The summer of 2023 will go down as the hottest in recorded history (thus far). Sadly, hot ocean water means coral bleaching, and Florida’s corals suffered tremendously this year. Fortunately the Coral City Camera was in position to create the world’s most comprehensive in-situ coral bleaching timelapses ever documented by human technology. Many attempts have been made to record a coral bleaching event, but to our knowledge, this is the most complete and longest running coral time lapse made underwater in a coral reef environment. The time lapse begins on May 1st, 2023 and you can see that the staghorn corals start growing and branching quickly. However, by mid-July water temperatures have reached the critical bleaching threshold of 87 degrees Fahrenheit (30.5C) and quickly turn white. The transplanted staghorns and elkhorn corals not only bleached, but they subsequently died. You can see how after turning white, they turn gray-brown as they are colonized by turf algae in August and September, and then they erode almost as quickly as they grew, expedited by the abundant parrotfish that graze this algae from the corals’ limestone skeletons.

Bleaching occurs when the metabolism of the golden-brown symbiotic algae that live in the coral tissue known as zooxanthellae goes into thermal overdrive. The algae’s production of photosynthetically-produced oxygen exceeds the limit the coral can safely handle inside its tissues, resulting in expulsion of the zooxanthellae (and its brown color) from its host. Because zooxanthellae normally provide a coral with photosynthetically-produced sugars, it begins to starve without these symbionts. Fast-growing corals like the endangered staghorn (Acropora cervicornis) and elkhorn (Acropora palmata) lack the energy stores that fleshier corals like brain corals have, and die from bleaching stress much more easily.

By the end of August 2023, all of the staghorn and elkhorn corals experimentally-transplanted by the University of Miami’s Rescue a Reef program succumbed to the excess heat and bleaching. These were corals that are native to cooler, cleaner waters offshore Miami, so it didn’t come as a complete surprise that they could not survive the urban reef environment around the CCC. However, a single strain of staghorn and elkhorn coral that are native to the Port did not bleach and continued growing happily despite water temps exceeding 90 degrees Fahrenheit (+32C). Not taking any chances, we brought fragments of these urban strains of stag and elkhorn coral into climate-controlled conditions at NOAA’s Atlantic Oceanographic Marine Lab in July. Once water temperatures cooled enough, these fragments were safely returned to the CURES (Coral Urban Research Experimental Site) nursery frame that sits about 20’ from the CCC.

Many corals like the mustard hill coral (Porites asteroides) did not fully recover from bleaching until December 2023. Most of the brain corals had recovered from bleaching by November 2023.

Amazingly, a significant number of corals native to PortMiami did not bleach, suggesting that they have a combination of genes and microbiomes that have enabled them to adapt to the Anthropogenic conditions along Miami’s urban coastline. The native urban corals that did bleach managed to survive for several months without any zooxanthellae to provide them with energy, before recovering new zooxanthellae in autumn when cooler water returned. It is possible that the higher levels of nutrients and plankton in the water helped provide these corals with additional energy captured as food.

These urban corals and the bleaching timelapses highlight the scientific value of the Coral City Camera and its ability to document what was previously undocumented. After 4 years of near-continuous recording, and more than 205 species of fish cataloged, there is no underwater coral reef site anywhere in the world that has been as thoroughly recorded and archived.

While corals throughout Florida and the Keys suffered tremendously in the summer of 2023, the stressful event also demonstrated that not all corals shared the same fates. Even within the same species, some corals did not bleach, bleached and recovered, or bleached and died. Studying the resilient strains of urban corals at PortMiami may illuminate how they’ve been able to adapt to marginal conditions and excessive heat. With global fossil fuel emissions continuing to rise unsustainably, we can expect even hotter summers in the years to come. Will corals be able to adapt naturally fast enough? Will scientists be able to accelerate the evolution of these corals to withstand hotter water temperatures? We are in an existential race against time, but we believe (now more than ever) that Miami’s urban corals will play an important role in finding out what makes a resilient coral ‘super’. The newly launched Coral City Foundation aims to build a land-based coral lab in 2024 to unlock these secrets and amplify their numbers.

‘The Lettuce Slug’
Elysia crispata on Halimeda opuntia
Music, Video, and Aquarium
2010 Coral Morphologic

Lettuce sea slugs (Elysia crispata) are a commonly found in protected nearshore Floridian waters where green macroalgae proliferates. They belong to a clan of sea slugs, the sarcoglossans, that are characterized by their ‘sap-sucking’ feeding habits of algae. These slugs slowly patrol mangrove roots and rocks searching for green algae upon which they feed. They store some of the chloroplasts from eaten algae in their tissue, giving it the green coloration. The chloroplasts continue to function, providing the slug with photosynthetic energy. The ruffles along the back of the lettuce sea slug are called parapodia, and help provide more surface area for the chloroplasts to inhabit. They also camouflage the slug amongst the leafy algae that they live amongst. It is very easy to swim past a lettuce nudibranch without ever noticing it.

The scrolled rhinophores (antennae) on the head of the lettuce sea slug help detect the chemical fingerprints of their preferred algal species. If you look carefully, just behind the rhinophores, you’ll notice the small black eye spots that act as rudimentary eyes to detect changes in light and dark.

The macroalgae featured in the film is Halimeda opuntia, (named after its resemblance to the prickly pear cactus Opuntia sp.). It is unique amongst green algae in that it produces a semi-rigid, calcareous skeleton. In fact, the dead ‘leaf’ fragments of Halimeda spp. algae are a more significant producer of coral reef sand than the corals themselves. It is not uncommon to find lettuce sea slugs on Halimeda opuntia algae, as it frequently lives amidst the softer green algae that the lettuce sea slugs prefer.

‘Complex Nano’
Music by Space Voodoo Crystal
Video and Aquarium
2010 Coral Morphologic

Above is a short video featuring a glow-in-the-dark perspective of the 5-gallon ‘Complex Nano’ reef aquarium. A daylight photo of this aquarium is featured in the April/May – 8th Anniversary Issue of Marc Ecko’s Complex Magazine (see below). By comparing the two differently illuminated versions of this nano reef, the true fluorescence of the corallimorphs and zoanthids immediately becomes apparent. The fluorescent pigments of the corallimorphs and zoanthids are preferentially activated under the 470 nm blue wavelength LED lighting used in the video. Notice that the normally bright orange coloration of the clownfish (Amphiprion ocellaris) appears nearly black in the film.

Both of the fish in the aquarium are captive-raised by the Harbor Branch Oceanographic Institute’s ornamental aquaculture subsidiary ORA. ORA has been a leader in this field, and we stand fully committed to the further development of  aquacultured ornamental marine fish species. You’ll notice that the normally three-striped clownfish has an unusual cross-pattern on one side. This is the result of selective breeding on ORA’s part.  In recent years, clownfish hatcheries have developed all black, white, orange, and ‘Picasso’, variations of the standard ‘Nemo’ through patient breeding and selection.

The other fish in the aquarium is an orchid dottyback (Pseudochromis fridmani). Wild versions of this fish tend to be more fiesty and territorial, whereas hatchery-raised fish tend to be more gregarious and better suited for life in a community reef aquarium.

Note the commensal (and nearly translucent) Pederson’s cleaner shrimp (Periclimenes pedersoni) on the fluorescent orange (Ricordea florida) corallimorphs in the video.

Click here for a complete species and hardware list

Special thanks to Patrick Albertson (article author) and Space Voodoo Crystal (soundtrack)

‘The Arrow Crab’
Stenorhynchus seticornis or ‘Arrow Crab’ guarding a cave entrance
Music, Video, and Aquarium
2010 Coral Morphologic

Take a moment to look into the compound eyes of the arrow crab (Stenorhynchus seticornis). If NASA is looking for a robot capable of navigating rocky planetary terrain, the arrow crab would be a perfect organism to model it after. In the video we look down the sharp, pointed rostrum (‘nose’) of an arrow crab as it appears bobbing in space. In reality, its spindly, spider-like legs are holding it anchored like a sentinel, guarding the opening of a small cave.

Arrow crabs are an abundant species on Floridian reefs, living perched near cracks and crevices in coral heads where they can retreat if threatened. Their pointed rostrum, triangular body, and protruding eyes gives this crab the appearance of a predatory lizard fish that can dash away at a moment’s notice. Instead, the arrow crab is rather slow moving, relying on the fact that the paucity of meat inside the spiny, twig-like exoskeleton of the arrow crab makes it unappetizing to a would-be-predator. This unique anatomical configuration likely explains their abundance in the wild.

Like other decapod crustaceans, the arrow crab has 10 legs (8 walking legs, and 2 pincers or ‘chelipeds’ properly). However, if you look carefully, you’ll notice that this particular crab is missing the last leg on the right side of its body. Fortunately, crustaceans are capable of regrowing amputated legs. Only a few hours after it was filmed, this arrow crab molted, and as if by magic, regenerated its tenth limb.

‘Purple Forest’
Decorator Crab (Microphrys bicornuta) on Asparagopsis taxiformis algae
Music, Video, and Aquarium
2010 Coral Morphologic

This week’s video features an aquascape comprised of the beautiful purple macro algae Asparagopsis taxiformis. However, if you pay close attention to the left 1/3 of the screen, you’ll notice something… moving with claws. Nestled amongst the algae is a perfectly camouflaged decorator crab (Microphrys bicornuta). Keep paying attention… at 26 seconds into the clip you’ll notice a tiny isopod crustacean float by in the current and descend helicopter-style right onto the crab’s back. The unsuspecting isopod has no idea that it has landed upon an algae covered beast. Furthermore, it appears that the crab is not aware of the unexpected visitor until the isopod begins to explore its decorated exoskeleton.  50 seconds into the clip the isopod meets its fate with a few swift snatches of the crab’s claws. Without missing a beat, the crab continues scavenging amongst the rocks and algae. And life on the reef goes on.

Decorator crabs are amazing creatures in that they pick up pieces of their surrounding habitat and place them on their carapace (back, exoskeleton) in order to blend into their surroundings. Decorator crabs that live amongst sponges decorate with sponges, those that live amongst zoanthids use zoanthids, and so on. This instinctual logic is truly remarkable. The crab in the video has attached small pieces of the Asparagopsis upon itself, and as a result is all but indistinguishable from its surroundings.

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