Comparing Invertebrate Counts

The invertebrate creatures that life on the coral reefs are in integral part of the vast and complicated ecosystem that has been referred to as the rainforest of the oceans. There is much about these ecosystems that we do not understand, and compiled with the complicated effects of human impact reefs makes it even more difficult to understand. However, after compiling years of data and the results inferred, it has been determined that there are key indicator species that can be used to determine the health of a reef. Almost as one would do with a canary in a mine shaft.

The species that have been determined by Reef Check to be indicator organisms based on economic (harvested for the aquarium trade) and ecological (balancing the algal growth) value are;
1) Banded coral shrimp (Stenopus hispidus)
2) Diadema urchins
3) Pencil urchin (Eucidras spp.)
4) Collector urchin/sea egg (Tripneustes sp.)
5) Triton (Charonia variegta)
6) Flamingo tongue (Cyphoma gibbosum)
7) Georgonian (sea fan, sea whip)
8) Lobster (Palinuridea)

While in our reef ecology class we reviewed and studied an article that studied and almost certainly concluded that the diadema (black spine) urchin was not only integral, but perhaps the most important, or key stone, invertebrate species within the coral reef ecosystem. Following a mass die out of diadema (aprox 95%) in 1984, the increase of alga was almost instantaneous. However, since the return of the diadema in recent years (since the mid 90s) they greatly reduced microalgal (from >60% to <5%) which in turn increased coral growth. The study was conducted throughout the Caribbean, but the discovery of the impact of the diadema was a place called Dairy Bull, in Jamaica. It was here that there as actually been an increase in coral cover in the past two decades (in vast contrary to the rest of the Caribbean), almost 100% more living coral and 90% less algal cover then it did in 1995. This coral growth is occurring even while overfishing is still a problem. This phase shift in coral growth  appears to always be preceded by the recovering and increased population of the diadema urchin.
Source:
http://www.int-res.com/articles/meps_oa/m403p091.pdf

On the first dive located at, Buena Vista, we discovered invertebrate species in the low single digits only. This had also been a trend in most of the dive sites we had been to prior to our Reef Check dives. In addition to the lack of invertebrates, their was large amounts of coral disease and bleaching. Their was a large amount of algal proliferation, as well as a great over abundance of georgonians. The site just looked sick.

In contrary, the second dive site, Coral gardens, looked radically healthier. The amount of diadima urchins was around 50 and pencil urchins was even more then that. Also, reef urchins, which are not counted by Reef Check would have easily surpassed 200 if they had been counted. There were more flamingo tongues, and even two collector urchins, the georgonian count was also much lower. The coral substrate itself was vastly more abundant and disease and bleaching was far less prevalent. Also, there was significantly less algal proliferation. Both sites are legally allowed to be fished and the species discovered at each site were about even.

With out conducting a purely scientific study we can not make any fact based conclusions. However, from the data we gathered and what we were able to see just from being there supports the findings of the article we studied in class and the study it was based on. The diadema urchins, and other herbivores are indeed a keystone species. They are integral to the promotion of of healthy coral and increased coral growth. In addition to this, what we observed at another site, Hol Chan, also supports the article. While not a Reef Check site (so we did not study, just notice and observe), it is protected from fishing, which means far greater number of fish species. However the overall health of the site was less the that of Coral Gardens, and in parallel to that the amount of diadema we noticed was far less.

The coral reefs are an incredibly complex biosphere, and the more we study the more we learn. Reef Check, and the observations we make while conducting it, is an invaluable asset into this learning process. Just seeing that the two locations we studied were so different and the species we found in each site is an enormous help. The fact that what we found supports conclusions by other scientific data is large step forward in the understanding of healthy reefs. Hopefully, with time , the damage that has been done to the reefs can be stopped and the health of these underwater biosphere can be returned to their natural unparalleled state of beauty.

 

 

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They paved paradise and put up a parking lot…

The other day we rented golf carts and explored the island. It was an eye opening experience. We ended up going from one end of the island to the other end. One of the most interesting things we saw was the new construction going on. They are slashing and burning the mangroves that protect island from erosion and provide a habitat from the smaller animals that seek protection on the island. They then back-fill the areas that were dug up and build on top of that new land. Unfortunately because there are no mangroves in that area, often times the new construction gets flooded and the building’s foundation crumbles, making the property worthless. We saw a lot of properties on our trek that were outright abandoned and destroyed. One that comes to mind was the resort “The Journey’s End” on the north side of the island. It used to be one of the most expense, high end, sought after resorts on the island but the management gave up on the property and decided to build a brand new resort down the street. We found out later that the property was now occupied with a settlement of missionaries that were slowly rehabilitating the resort.

One of the main issues surrounding the new developments are the workers. The workers for these new resorts and luxury condos are under paid Mexican laborers that come over the border from mexico (the border is 5 miles away). the workers undercut the local construction workforce, do a worse job, live unsustainabily in shanty towns and are slowly killing off the environment.  Due to the low cost of their labor the island is losing jobs, land, and natural wildlife.  At this rate, in a few years there will be no natural beauty to see.

Transportation

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San Pedro is a relatively small island, however it is so busy, with people trying to get from one place to another. Golf carts are by far the most popular way of getting around. The few cars on the island are usually taxis, and often have trouble navigating the tight city streets. They represent a very small percentage of the total vehicle population. Bicycles are also very popular, because they are cheap, allowed on the beach, and have no fuel costs. This is very important, because although the cost of living is generally lower than it is in the U.S., gas prices sit at around $14 Belize per gallon. I talked to shorty about it on our way to a dive, and he said that although Belize has oil, it doesn’t have any refineries. It has to send its oil to Venezuela to be refined and then buy it back as gasoline and diesel. The high gas prices make golf carts very practical, as they get 45 to 50 miles per gallon. Boats however, consume a lot of fuel and are a staple of island life. Obviously getting to or from the island requires use of either a boat or a plane, but there are even parts of the island that are unacessable by roads and require Marine transportation. These are mostly very expensive resorts in the northern region of the island. Outside of the city, the roads are unpaved and unmaintained, full of ruts and potholes. For this reason it is popular to run atv tires on the golf carts. The northern side of san pedro is quickly being developed, and if the population of the island grows at the same rate that the resorts are, the city will need to work on its infrastructure in order to accommodate the increase in traffic. It will be interesting to see how the small community changes in the coming years.

What we are actually doing

A brief overview of what we are doing and why we are here, with out getting into too much detail or getting too complicated.

The coral reefs around the world are dying, a variety of reasons contribute to this tragic fact; over fishing, climate change, water pollutants, and degradation of terrestrial habitats are thought to be some of the causes. However, because of the sheer expanse of the coral reefs its very difficult to pinpoint many of the whys and hows. Also, these different causes have a varying effect on the complicated ecosystem of the reefs. Regardless of this, the more data we have the more solid conclusions we can come to. That is were Reef Check, and people like us come in.

Because of the expanse of the coral reefs, the job of surveying and studying them can not be left to scientists alone. Reef Check was created to establish standard parameters and methods in which citizen scientists could work with and under qualified individuals to gather the necessary data around the world. Some of the goals of Reef Check are to educate the public about the reef crisis, create a global network of volunteers, scientifically investigate the coral reef ecosystem, and to stimulate the local community into taking taking action to protect their reefs.

The first thing we do is lay out a 100m transect line along the chosen reef that meets the required criteria. This is done at two depths, one of 3m and one of 10m. Then using that line we collect four types of data:
1) A description of each reef site based on over 30 measures of environmental and socioeconomic conditions and rating of human impact.
2) A measure of the percentage of the seabed covered by different substrate types, including live and dead coral, along four 20m sections of a 100m shallow reef transect.
3) Invertebrate counts over four 20m x 5m belts along the transect.
4) Fish counts, up to 5m above the same belt.

We took the reef ecology course to learn about the reefs and their ecosystems, as well as their global impact and importance. We all had to be SCUBA certified , as well as spend time learning the diving skills required to collect the data. Then it was our job, broken up into assigned teams, to collect and record the data under these parameters.

Invasive Lionfish

I was very curious to talk to someone about lionfish, since I know it is an invasive species in the Atlantic and they are quite overpopulated. Diving the past week and a half, I have been very surprised to not see that many. On day 2, a lionfish was spotted on an artificial reef off the end of a dock. He wasn’t very big. A couple days later Jimmy was snorkeling off the end of Ecologic Divers’ dock before a dive and spotted 2 little lionfish hovering at the bottom. He let a couple of the workers know and they jumped in and speared the fish. It wasn’t until diving out in the Great Blue Hole and the dive sites nearby that I encountered some very large lionfish. A total of three were counted lingering around the reef waiting for prey to swim by and be eaten up. There were many fish at Lighthouse Reef, due to it being a marine reserve, so the lionfish were living like kings, overindulging on the other fish. A final lionfish was discovered on the night dive we did at Hol Chan Marine Reserve yesterday. Wondering why there weren’t many spotted, I decided to talk with a local. I was informed that the reason why I was not finding any lionfish on the dives outside the reef was because they like to hang out within. They choose to do so because that is where all the smaller fish hang out; smaller fish are easier prey. They are also primarily located on the south side of the island, not a place where we have really been diving. The locals try to curb the population by spearing them whenever possible. This is a reason why barracudas tend to swim by your side: they are waiting for their fish handout, like your pet dog follows you for a treat. Nearby restaurants specialize in lionfish cuisine. I have yet to try it, but want to venture out to get some before our departure. Ultimately, the overpopulated lionfish has not yet taken over the reefs along San Pedro. Hopefully predators will catch on from the handouts and start feeding on the lionfish themselves.

Jimmy and a speared lionfish.

Jimmy and a speared lionfish.

Lionfish at lighthouse reef.

Lionfish at lighthouse reef.

Barracuda swimming alongside.

Barracuda swimming alongside.

Nightswimming deserves a quiet night.

People often talk of nostalgia, of the good times where an unexpected event was shared between a group of people. Tonight, our band of merry scientists have something to bond over for the rest of our lives. Not only was it the last dive of the trip but also it was something that was truly unique, a night dive. We had been pushing for one all trip and finally we got an opportunity. Our entire time down here, the weather had not agreed with us. Today though, it was our chance and we could not have asked for a better night to dive. We had a fairly calm current going out. Although we had to kick a little bit harder on the way out, our return was nice and easy with no effort at all. Along the way, we saw lobsters, sting rays, parrot fish, snappers, and many other aquatic life. I personally saw a lion fish. The sighting of the night was by Dr. John. He saw a moray eel having a little late night snack on a parrot fish. It was a really cool experience at about three quarters of the way into the dive. We stopped at a sandy spot, gathered round together and turned off our flashlights. Slowly we waved our hands in the air and the bio-luminescence turned on like tiny black lights all around us. It was something to be seen. Although not everyone enjoyed the dive as much as the group(its pretty scary in the dark ocean at night), everyone can say that it was an experience that they’ll never forget.

Reef Check Fish Count

On Monday we began collecting data for ReefCheck at a site called Buena Vista. I was assigned to the fish count, and the night before I spent anxiously reviewing fish i.d. and worrying about how I was going to count large schools of snappers or grunts. I have some experience estimating flock size when birding, but the flocks I count usually don’t fly in tight circles, whereas schools of fish often seem to swim in a circular pattern. As it turned out, my anxiety was unnecessary. Between Alyssa and I, we tallied two grunts and three snappers. A couple of butterfly fish rounded out the count. If I came to San Pedro as a tourist instead of a student, I think it would be easy to appreciate the splendor of the barrier reef and not notice the declining health of this underwater habitat. Oftentimes, I found myself marveling at the beauty of a particular site when I climbed back onto the boat after a dive, and it was only after reviewing the video tapes that I began to recognize the extent of the damage to the reef, including the amount of algal cover and the numerous patches of diseased coral. The fish count seemed depressingly low to me, but I am curious to compare the data we collected from Buena Vista to the data collected on previous fellowships. One very enjoyable part of the dive was a beautiful French Angel spotted off the transect line and recorded as a rare animal. I think part of the reason that creating awareness of the crisis facing coral reefs around the world is that even an unhealthy reef is gorgeous and fascinating to the untrained eye. Reef Check selects certain species to serve as indicators of the overall impact to the reef, but non-indicator fish often appear abundant. I have seen more Blue Chromis, Creole Wrasse, and Atlantic Blue Tang than I could count. On Tuesday we surveyed a shallow water site called Coral Gardens, and the difference was startling. Grunts were seen in the dozens, and multiple species of snapper, including the silver and yellow Schoolmasters were tallied. After a surface interval on the boat, I went “freediving” with a nurse shark, stingray and two barracuda . Coral Gardens was an  encouraging conclusion to our study.