Our last day on island was one of moving and reflecting….We left VIERS at 8 a.m. and arrived back at Hollins at midnight. Plenty of time to reflect on our action-packed Journey. In only 10 days on island we: snorkeled in the day at 17 different sites; did two night snorkels; cleaned up 4 beaches and removed over 205 pounds of debris (mostly plastic); hiked at night, in silence, without flashlights, on 4 different occasions; watched at least two sunrises; visited 6 sugar plantation ruins and wrestled with the pain of the sugar-coating of the brutality of slavery which shapes this landscape and its people; laughed; sang; danced; ran; swam; and collected data to find out answers to our research questions. While we were each one of 20, we came to value that as a group we were even greater than the sum of our own individual experiences. It was difficult to realize that our group would soon be dispersing.
Snow greeted us on our return providing the perfect backdrop for three intense days of data analysis and the development of research posters which will be presented in April at the 57th Annual Hollins Science Seminar. Below are summaries of our findings:
The Brainiacs: Ashley, Mae and Natasha
We were interested in the impact of water pollution on coral health. So we compared brain coral health in watersheds with varying levels of human development on the island of St. John, USVI. Using 10 meter circular transects, the number, size, and relative health of brain coral was assessed in 9 different watersheds – a total of 27 transect surveys were conducted. Analyzing the data collected, we found that there was a significant increase in the density of coral in watersheds with low disturbance when compared to those with higher levels of disturbance. Larger sample sizes and more sites in higher impacted areas could shed more light on this issue. We are definitely ready to go back next January and dig a bit more into this issue!
Queen Conch Fritters – Sam Cline
In shallow water environments in the Caribbean, the Queen Conch (Strombus gigas) mollusc plays an important biological role as an algal grazer and detritovore. Because it is an important fisheries species as well, its populations have declined (at one inshore site off the island of St. John, USVI, the Queen Conch population declined by 97% over a 5 year study period 1986-1991). As a pilot study, I was interested in determining the current population density, size, and age class of the Queen Conch in sea grass beds of St. John, USVI. Shell length, lip thickness, depth, location, and signs of harvest were recorded during each ten minute swim survey. I found a total of 32 live conch were found (21 juvenile, 11 adult). No empty conch shells had indication of illegal harvesting. There was a significant positive correlation between shell length and depth at which conch shells were found. While these findings suggest an overall decline in Queen Conch population compared to historic population estimates, the 1.9:1 juvenile :adult ratio suggests that there has been some recent reproductive success and that the population may be able to recover. Additional survey sites and survey replication over time will provide important information for Queen Conch population size and may help guide regulation patterns.
Getting to the Point: Urchin Populations and Coral Health – Natalie and Brittany
The health of coral reefs are dependent on organisms that graze algae such as the long-spined sea urchin Diadema antillarum. According to Lessios et al. (1984), the condition of USVI coral reefs was significantly impacted by a tremendous die-off of the long-spined sea urchin in the 1980s. We were interested in surveying the population of long-spined urchins and in correlating their population density to coral population patterns. We carried out 20 minute swimming surveys of long-spined urchin numbers in four bays surrounding St. John USVI and found that there was a significant relationship between urchin population number and the number of brain coral classified in a “small” size class. This positive relationship with urchin density and young brain coral suggest that the population rebound of urchins may benefit the regeneration of brain coral on reefs.
Stripes and Patterns – Felicity and Brenna
The Lutjanus apodus (Schoolmaster) fish experiences metachrosis prompted by a variety of external and internal factors including change in background color, habitat, excitement, courtship, feeding and threat of predation. We were interested to see if we could detect a relationship with color change in this species with its activity level and habitat. We collected data in three different habitat types: Mangrove, reef and grassbed. At each site we would swim from one end of the bay to the other and note the number of schoolmasters seen, striping patterns, activity level and whether or not they were in a structure. We found the highest population density of Schoolmasters in the mangrove and grassbed habitats but surveyed more reef habitats. Most schoolmasters detected were striped, however, we found no relationship between striping patterns and activity level and habitat. We concluded that further research and a larger sample size are necessary to achieve more definitive results.
Boulder Bunch – Rory, Andi, and Lucy
Major coral bleaching events in the Caribbean in 2005 and 2010 has caused significant mortality of coral in reefs surrounding St. John. We were interested in assessing the population patterns of Grooved Boulder Brain coral (Colpophyllia natans) in mangroves, coral reefs and in colonized pavement habitats. We predicted that coral in shallow mangrove habitats would be more susceptible to temperature oscillation and might have more health issues. Using 45 minute swimming surveys, we estimated brain coral health and size in these three environments and found no correlation between brain coral health and habitat. However, 61% of the brain coral we found was classified as small and in good health indicating that there is recruitment of this species in all surveyed areas. These findings suggest that boulder brain coral may be recovering from the most recent bleaching events. More research should be conducted to confirm these findings.
Sensitive Feathers – Amy
I was very interested in studying the behavior of a marine species and settled my research question on the magnificent feather duster, Sabellastarte magnifica, a species of stationary marine worm which lives inside self-constructed tubes exposing only their branchial crown exposed, for both respiration and filter feeding. When disturbed, these worms will retract in order to avoid predation. I expected to find that magnificent feather dusters would display a lower sensitivity to disturbance in shallow waters or waters with high wave action. In order to test this I approached feather dusters at different depths and in different water conditions and squirted water from a syringe towards their exposed crown. I found that feather dusters in shallow and medium depths were significantly less sensitive to sea water administration than those in deeper water (ANOVA P = 0.02). In addition, I found that worms exposed to greater natural wave action were less sensitive to sea water administration than those in calmer habitats (KW P = 0.004). These data suggest that magnificent feather dusters situated at shallower depths and in areas of higher natural wave action may be more vulnerable to predation – a finding that bears further investigation.
Lionizing shifts in Biodiversity and Abundance Patterns – Kristin
Lionfish are voracious predators that were first found in St. John in March of 2010. Their full impacts on coral reef health and biodiversity are not known, but studies have shown that the presence of lionfish on a reef can reduce the recruitment of native fishes by up to 80%. For the past 3 years I have estimated fish biodiversity in 10 sites (four habitats). At each site I conduct a 10 minute swimming survey and note species and relative abundance. When comparing across years, mangrove habitats showed the highest rate of decline in abundance while the other 3 habitats (grassbeds, colonized bedrock and coral reefs) showed reductions that were not as dramatic. The rates of decline in abundance of species on Coral Reefs were greater between 2012 and 2013 than between 2013 to 2014. These findings suggest that there are negative impacts to populations, however, improvement in the ability of species to recognize the lionfish as a predator or the continual effort by dedicated volunteers to keep lionfish populations in check may help to stabilize reef fish populations.
Do Tell: Understanding Tourist Activity and Knowledge – Jentry, Suzanne, and Melissa
Educated tourists often have less impact on the places they visit and often have richer experiences. We wanted to assess the historical and environmental knowledge of tourists that were visiting St. John, USVI. As such, we interviewed 111 people, 98% of whom were white Americans with an average age of 46. Approximately two-thirds of the Americans were from the northeastern U.S and over 40% were able to correctly identify rainwater as the primary freshwater source on the island. We did find that those tourists that had visited St. John more than 6 times were more likely to understand water issues relevant to the islands than those less frequent visitors. Over half of the tourists indicated that slavery and plantations had important historical impacts on the island. Analysis of this rich data set will continue, but these preliminary findings suggest that a significant number of tourists are unaware of important environmental and historical issues.
The Parrotheads – Sarah, Caleb, Captain Morgan, Commander Renee
The status of parrotfish populations are a good indicator of coral health, as they play a key role as algae grazers in sustaining coral reef habitats. Without this grazing, algal growth may inhibit photosynthesis of the coral’s symbiotic algae (zooxanthellae) as well as promote bacterial growth. Our project is focused on understanding the abundance and sex ratio patterns of parrotfish in different marine habitats (colonized pavement and coral reefs) in St John over a two year time period. We compared abundance patterns between these two habitats as well as between years and relationship to protected park waters. Parrotfish were found to be more abundant in reef habitats and showed a decline in abundance from 2013 to 2014. Two species which showed dramatic declines in abundance exhibited a decrease in the ratio of initial to terminal fish. These findings suggest that there may be weak recruitment of initial parrotfish which are all female over the last year. This finding bears further investigation as parrotfish populations are an important component in maintaining coral health.
It has been a grand learning experience – one we were privileged to lead!