The Daily Bucket is a regular feature of the Backyard Science group. It is a place to note any observations you have made of the world around you. Rain, sun, wind...insects, birds, flowers...meteorites, rocks...seasonal changes...all are worthy additions to the bucket. Please let us know what is going on around you in a comment. Include, as close as is comfortable for you, where you are located. Each note is a record that we can refer to in the future as we try to understand the patterns that are quietly unwinding around us.May 2014
My backyard for the first half of May was an offshore atoll in the Caribbean. I go to a coral reef every year somewhere because that underwater world is my element and my passion. And I feel a sense of urgency, knowing the reefs are declining radically, even within my lifetime.
One feature of the healthy reefs I've dived is remoteness from human activity. The outer atolls of Belize are relatively remote. It shows. Out beyond the barrier reef, the atolls are 1.5 - 2.5 hours by boat out in the open sea. An atoll is a ring of coral that emerges from the water surface in some places, forming small mangrove islands (cayes), with the whole ring enclosing a shallow lagoon.
Besides a handful of dive resorts, local fish camps and two scientific research stations on a few cayes, the atolls are uninhabited. This limits sedimentation and pollution.
A healthy reef is packed with a diversity of living corals and the creatures who depend on them, like these Spotted Eagle Rays. I saw Eagle Rays every day! Other places I've dived, I might see one in a week.
(Note: I do not have an underwater camera. All these images are either given to me by fellow divers, or in the public domain. I saw everything pictured here.)
The large number of species I saw, and the numbers of individuals indicate a stable ecosystem with adequate resources.
I witnessed the spawning season of the Sharp-Nosed Puffer over a week. At first I couldn't understand why the water was filled with these small 2" colorfully patterned fish, but after a few days I began seeing them in pairs, with some dead spent bodies lying on the bottom. Imagine swimming in the middle of hundreds of these little fellows, following each other, darting out attacking interlopers, hovering together.
A coral reef ecosystem has many interspecies interactions too. Cleaning stations are one of my favorite to watch. At these spots, which look just like any other to me, an absolute truce exists. Large fish hover, mouths and gills agape, while tiny wrasses, blennies and shrimp crawl in and out snatching up parasites...the big fish get cleaned and the small ones get food, a mutually beneficial relationship.
Another sign of a healthy reef is the presence of both young and old individuals of a species. Fishing usually takes away the largest, most prolific members of a population, resulting in fewer young. I saw various aged fish, such as these Spotted Drums. They all have a strange swimming style, round and round, under an overhang.
The atolls of Belize benefit from more protection from fishing than most reefs in the Caribbean. Portions of Lighthouse Atoll (beginning in 1928) and Glover's Reef (in 1993) were established as a National Monument and a Marine Reserve, respectively. Turneffe Atoll was declared a Marine Reserve in its entirety in 2012. Their protected status, the influence of the dive tourist industry and their distance from the mainland population centers means the atolls have larger - older - fish I don't usually see elsewhere. Groupers were common, larger than the one in this photo.
I even saw two huge Loggerhead Turtles. Hawksbill Turtles were fairly common.
I generally dive with a few other people and a dive guide from the resort. We don't talk during a dive (mouth full of a regulator!) which is really a lovely experience, just you drifting in that sensual world without human yackety yak. So every now and then when the dive guide wants to show you something cool, he gestures with basic hand signals. One time he gestured something I didn't understand at first, waving across the reef. He meant: "healthy coral". Yes! I'd been so intent on seeing a Toadfish hidden in a crack or a sleeping Nurse Shark I hadn't gazed across the whole reef - swaying gorgonians, colorful brain corals, lavender sea fans, giant knobby barrel sponges, busy with hundreds of fish at their day's work.
Nearly paradise. The threats to coral reefs were evident even out there though. In places, a red slimy cyanobacterial mat covered a coral head. I saw this less in the easternmost sites, at Lighthouse Atoll. This "algae" grows in places of high nutrient load, such as sewage, fertilizer, decomposition, eg. swept in from human habitation and agriculture. Algae covers and suffocates coral, and is a bigger threat in the Caribbean than the Pacific. This makes the invasive Lionfish an even bigger disaster than they'd otherwise be, since they feed on small herbivorous fish (more on what I saw of the Lionfish in a future post).
I also noticed far less Staghorn and Elkhorn coral, the branching type. Disease and coral bleaching due to the warming ocean have killed off much of these fast-growing corals in the Caribbean. There's a cascade effect in the ecosystem. For example, Damselfish, which ordinarily cultivate and defend algae gardens in branching coral, have moved to the slower-growing coral heads, where they have less protection and do more damage with their "death-bites". Here's a damselfish in its preferred coral home, of which I saw few on this trip.
In spite of these warning signs of decline, I still travel to the reef each year and dive, feeling immense gratitude I'm alive to still see this wonderful complex beautiful world.
Don't know if this link will work, but if you can play it, you'll see bits of one day of our diving on this trip, a day trip over to Lighthouse Reef atoll. Michael Davis is a videographer who filmed and put together this movie. You can get a sense of what it's like on a dive. Please turn off the sound though - there isn't zippy music playing under water...imagine instead the sound of water gurgling quietly :)
The Eagle Rays wave bye bye...
That's a bit of my aquatic backyard. What's up today in your natural neighborhood? All observations are welcome.
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