For the past few months, 3rd and 4th grade students from Ocean Studies Charter School have been growing red mangroves in their classroom in preparation for planting at MarineLab’s restoration site. The students monitored the mangrove propagules while in their classroom, conducting their own study on the salinity preference the propagules grew best in. Today, the students came to MarineLab to put their baby mangroves back into the wild where they belong.
As seen in previous posts we are working hard to determine the best methodology and protocols to follow at the restoration site at MarineLab. As there is not ample protection from the wind, waves and wrack line, the restoration site is not ideal. We are slowly learning the techniques that work best at this site. As we prepare for a group of local fourth grade students to come and plant the propagules they have been growing in their classroom for the past few months, the site was recently monitored, taking notes of height growth, growth in trunk circumference, and the number of prop roots. In the past few years, we have had some great successes. Check out the photo below of mangrove #35 and #44- big and healthy! We have constantly been learning about what works and doesnt work and updating our methodology accordingly. In one of the photos below, you can see that #46 was completely submerged, even at low tide- doomed for failure! It is important that the PVC is at the correct height where the planted propagule spends a portion of the day submerged and a portion completely out of the water.
Since 2012, MRDF’s MarineLab instructors have been assisting University of Miami’s Dr. Larry Brand in collecting water samples in Florida Bay for cyanobacteria analysis. Read more about the project here: http://marinelabresearch.wordpress.com/2012/08/15/why-are-we-concerned-about-cyanobacteria-in-florida-bay/
While many of MarineLab’s students are enjoying the end of their holiday break, our MarineLab staff was hard at work collecting research data for our various research partnerships. On a particularly beautiful day last week, the MarineLab staff headed out to retrieve our phytoplankton monitoring screens at our various study sites on the reef
These phytoplankton screens are deployed as a part of NOAA’s Phytoplankton monitoring network (See experiment apparatus here: http://marinelabresearch.wordpress.com/2013/07/25/toxic-phytoplankton-study/) Phytoplankton are an important biotic component of the coral reef ecosystem, and are the principle primary producers of the ocean food web. In this particular study, NOAA scientists and MarineLab staff are investigating a specific group of phytoplankton known as dinoflagellates. If there is a bloom of dinoflagellates, it can potentially lead to Ciguatera Fish Poisoning!
Moon jellyfish season is something we are used to dealing with here in the Florida Keys. The sting from a moon jelly is mild and they are actually quite beautiful to observe but, as jellyfish are one of the most feared organisms of our oceans, snorkeling with students at a reef with swarms of moon jellyfish is anything but a mild and beautiful experience. There is little we can do to prevent the students from screaming and thrashing as if a great white shark was barreling towards them with its jaws wide open. So, we patiently wait for the moon jelly season to end as they drift to another location. But this season, my patience is wearing thin. The swarms are only getting larger. I can’t help but wonder if the jellyfish invasion I have read about is actually happening before my eyes as I ignore it, simply reminding the students to stop screaming, keep their faces in the water and swim around them.
Over recent decades, man’s expanding influence on the oceans has begun to cause real change and there is reason to think that in some regions, new blooms of jellyfish are occurring in response to some of the cumulative effects of these impacts. The link between ocean degradation and jellyfish makes biological sense. Nutrient pollution can increase food supplies for jellyfish, overfishing can reduce their competition, and warmer temperatures are thought o trigger reproduction in some jellyfish species.
By the pulsed nature of their life cycles, gelatinous zooplankton come and go seasonally, giving rise in even the most undisturbed circumstances to summer blooms. Even holoplanktonic species like ctenophores increase in number in the spring or summer when planktonic food is available in greater abundance. Beyond that basic life cycle-driven seasonal change in numbers, several other kinds of events appear to be increasing the numbers of jellies present in some ecosystems. In 1996, Dr Graham of the University of Mississippi reported that from 1985 to 1997, moon jellies of the Gulf of Mexico had grown substantially more widespread and abundant. In the Bering Sea, one of a handful of locations with a monitoring record longer than a few years, jellyfish numbers had also risen through the 1990s.
However, some researchers in the Gulf and Bering Sea now believe that long term natural climate cycles have an important role in controlling populations there. Jelllyfish naturally form blooms. The challenge for researchers lies in separating normal fluctuations from those for which humans might deserve some of the blame.
A recent study (Graham 2012) suggests that as of right now there is not enough evidence to support a global upswing in jellyfish populations. A problem with jellyfish is that they are difficult to study so they have received little attention from marine biologists. We have little long term data. Typical nets shred them and many jellyfish have complex life cycles. Several species, including moon jellyfish, reproduce sexually to form larvae that settle on the sea floor and develop into anemone-like growths called polyps. If conditions are favorable, a single polyp can bud to form 20 floating jellies. But in hard times, polyps can produce more polyps or retreat into a tough cyst. Then when the environment improves, the waiting polyps can fuel a massive bloom of jellyfish. Bloom triggers seem to be tied to seasonal temperature changes which raises the possibility that warming of the oceans could indeed cause populations to increase.
The bottom line is we do not have enough information on jellyfish population changes to draw any true conclusions. In 2010, biologists created a jellyfish database initiative (JEDI), compiling every scientific jellyfish record they could find and they expect to continue expanding this resource. Citizen scientists are also called to assist through a website called jellywatch.org, through which scientists and citizens can report jellyfish sightings to help fill out the JEDI database.
Maybe telling the students that a jellyfish sighting could be beneficial to scientific research will help calm them down?? HAHA. Not a chance. The screams and flailing those moon jellies elicit are quite extraordinary. Until scientists collect more data, I will patiently wait for the moon jellies to drift away and remind the students to stop screaming, keep their faces in the water, swim around them. And enter the sighting into the database at jellywatch.org
Uye s (2008) Blooms of the giant jellyfish Nemopilema-nomurai: a threat to the fisheries sustainability of the East Asian Marginial Seas. Plankton Benthos Res 3: 125-131.
Condon et al. (2012) Questioning the rise of gelatinous zooplankton in the world’s oceans. BioScience 62 No 2
Graham et al. (2007) Numerical increases and distributional shifts of Chrysaora quinquecirrha (Desor) and Aurelia aurita (Linné) (Cnidaria: Scyphozoa) in the northern Gulf of Mexico. Ecological Studies 193: 239-255
While working with Dr Laurie Richardson of FIU and some of her graduate students, she promised to teach MarineLab instructors how to “suck up” black band disease that is affecting some of our stony corals. While on the search for some black band disease for Dr Richardson to give us a tutorial with, I realized that much of what looks like black band, in fact is not.
The picture above is of a stony boulder coral (Siderastrea siderea) at Grecian Rocks. Dr Richardson was unsure just by looking at the picture but thought what initially seemed to look like black band disease is actually some kind of competition with a sponge. As I have been looking closely for black band disease, I have been seeing this same sponge versus coral interaction on many of our stony corals. But why???
A study published in May of this year looked at sponges on Conch Reef, off of Key Largo (Pawlik et al. 2013). The study noted that as reef building corals have declined, macroalgae covers the greatest surface area on many reefs and sponges have become a primary component of coral reef ecosystems. The authors of the study were looking at bottom-up versus top-down effects of sponges, concluding that the Conch Reef sponge community, which they believe is a good example of most coral reef communities throughout the Caribbean, is structured primarily by top down effects (predation). As overfishing is still a problem throughout the Caribbean reef ecosystem, the loss of spongivores may have a drastic effect on our corals. The authors of the Conch Reef study predict that overfished reefs that lack spongivores will become dominated by faster growing undefended sponge species, which better compete for space with reef building corals. Sponge populations have already been proven to be increasing on Caribbean reefs and as the impacts of climate change and ocean acidification further disrupt marine communities, it seems likely that reef building corals and some macroalgae will suffer greater harm than sponges, which do not form limestone skeletons. At the current rate, Caribbean reefs of the future are likely to become increasingly dominated by sponges.
Nothing with the coral reef ecosystem is simple. Removing a disease is important and can preserve a single coral head but we must get to the source of the issues in order to preserve the entire reef ecosystem – water quality, fisheries management, ocean acidification, etc. in order to have a lasting impact.
Pawlik JR, Loh Tse-Lynn, McMurray SE, Finelli CM (2013) Sponge communities on Caribbean coral reefs are structured by factors that are top-down, not bottom up. PLoS ONE 8(5): e62573.
McMurray SE, Henkel TP, Pawlik JR (2010) Demographics of increasing populations of the giant barrel sponge Xestospongia muta in the Florida Keys. Ecology 91: 560-570.
The next time you see a conch shell, look closely. Students have been noticing octopuses residing in conch shells in the seagrass beds by Grecian Rocks reef. Octopuses are known to feed on conch. Perhaps the healthy conch population at Grecian is attracting more of these cephalopods to take up residence at one of our most visited reefs??