langzi's Journal

Authors- Sierra Nunis, Taylor English, and Ryan del Rosario

Introduction
Our project was focused on recording the species richness in a transitional fish pond in Pa'eam Tahiti. Species or taxonomic richness is defined as the amount of different species in an area. Our sampling universe was the area encompassing the fishpond from shore to the furthest wall, as well as two areas 15 meters adjacent to the pond. We specifically decided to expand on a previous years research on species diversity, with our focus on the specific sizes of two target families: the butterflyfish and damselfish. Our aim is to compare the abundance of juvenile butterfly and damsel fishes inside the fish pond compared to areas outside, which could indicate how effective the pond is as a nursery, the recruitment rate, or the fitness of individuals that use the pond for shelter.

Methods
We used the same methods as the prior group as follows. We separated into two phases; monitoring the inside of the fish pond (including a special survey of the central rock formation), and then monitoring the outer rock walls and a transect 15 meters longshore from the outer walls to provide comparisons. The first swimmer did one pass to record the species richness three meters away from the transect to make sure to not disturb the fish. They then waited 2 minutes at the end of the transect to allow fish to return before swimming back over the transect to make additional records. After a minimum of 2 minutes, we would repeat the same methods but would instead record the abundance of juvenile and adult target families of butterfly and damselfish. Juveniles were calculated as being under a designated range. We classified butterfly juveniles as 4 cm or under and Damsel juveniles were 3 cm or under. This was repeated by two researchers with a total of four complete laps. The same methods were repeated for the other two transects surrounding the inside of the fish pond,as well as the exterior and 15 m away.
In relation to the prior groups we decided to change the methods to surveying the inner fish pond. In past years they designated a researcher to swim for 10 minutes around the exterior and then 10 minutes observing the interior. We believe being inside the small interior would frighten the fish so we just surveyed the exterior. When surveying the exterior we concluded that the swimming around the exterior would scare fish so we decided to have one researcher stationary about ½ a meter away to record any fish richness and size of damsel/butterfly for a total of 10 minutes. To best estimate the size, a small rock prior to entering the water was measured out to be approximately 3 cm and was placed on the rock structure to precisely know if the fish is within our juvenile range when swimming past it. This was a total of 10 minutes of patrolling and made exact by an underwater watch.

We did further research on the direct outside of the right and left walls of the fish pond. We did this by using the same methods as the inside rather just a meter from the edge going to the outer lagoonside. We also conducted two further transects 15 meters away from the center of each right and left wall. These transects were also going 15 m crossshore and the same methods were used.

Results
​When looking at our graph, the x-axis indicated the areas surveyed, the bars indicate the classification of fish including their family and estimated age (of juvenile or adult), and the y-axis is number of individuals of each observed in their respective sampling universe. The adult damsel fish were the most observed, followed by adult butterfly, then juvenile damsel, and the least observed being juvenile Butterfly.The only location where neither were seen was the far right transect. The main locations for the juveniles were most abundant in the inner fish pond but juvenile damsel were seen in all but the far right, and juvenile butterfly were only observed in the inner fish pond, far left and inside right. But when taking richness survey data we used the highest number of observations and when taking the size data we used a small rock 3cm in size and placed it on the nursery so as to estimate size; and we classified them opportunistically so standard deviation isn’t necessary.
Data
https://docs.google.com/document/d/1LmZSOaD4YEh7sJmy8pC6VnOkvRDZvcdIu7gYCr1re3s/edit?usp=sharing

Discussion
Species richness was highest in the fish pond, particularly, inside of the central structure which was home to a variety of juvenile butterflyfish, gregories, and surgeonfish. Outside the fish pond, the majority juvenile observed were those of previously mentioned dusky gregories that made their home in tiny rock shelters.
Richness was much lower outside comparatively. There was a mix of both juvenile and adult fish of many families present, interestingly including a juvenile snowflake moray eel adult yellow boxfishm a meter and a half long flutemouth that was swimming among the fish pond’s interio, and an adult orange-lined triggerfish lodged within a solitary rock. In total, the fish pond was home to 15 different families of reef fish. In comparison directly outside of the fish pond there were 7 families on the right exterior and 5 on the left exterior.
The left area of the pond was notably more abundant in life than the right side. We propose this could possibly be due to the current going from south (left) to north (right) causing more sediment deposits on the left side. But further research is required to determine this hypothesis. On the left we observed 7 raccoon butterflyfish, three juvenile scissortail sergeants, and a solitary peacock damselfish. The right exterior meanwhile was relatively barren. Notably, however, it was one of the only locations where lagoon triggerfish were observed. Three juveniles that used the rock holes on the bottom for shelter.
In terms of abundance the Dusky gregories were by far the most abundant species in the area, living in practically every facet of the rock walls. Most were large, 6-7 cm adults that guarded their territories fiercely. Dusky gregories were observed constantly fighting back against other fish, including one scaring off an entire shoal of grazing sharpnose mullets. Furthermore, the presence of predatory fish like the flutemouth or eels could indicate attempts at predation which may be of interest to understanding the fish pond’s ecosystem. Butterflyfish like the vagabond and raccoon were spotted most often with a few speckled butterflyfish and a single threadfin butterflyfish being observed.
We would like to note that during our first day of surveying, there was a high in current due to the wind and weather conditions making the water have low visibility. The current also pushed surveyors so it was hard to maintain the set meter distance from our transects. The second day was better in visibility but current still posed a problem and we would recommend further research done on better weather conditions.
The fish pond’s diversity is certainly above that of the adjacent areas, being home to even large adult fish species. The presence of juvenile butterflyfish and damselfish indicates that it’s functioning as intended as a nursery for these species, indicating that it’s recruiting and maintaining young fish sufficiently well. For future surveys, we suggest broadening the scope of surveyed families to include all types of fish. Juvenile surgeonfish, eels, flutemouths, and emperor angelfish were also found in and around the fish pond. Looking further into their quantities compared to outside the pond will better quantify what thrives and relies on this miniature ecosystem. Furthermore, the behavior of specimens within the fish pond could be of potential interest. How often are they feeding? What is their alert and flight distance? How territorial are they? Compare all this to like specimens outside. Perhaps those in the fish pond feed more and are more territorial due to the limited space. It’s clear the fishpond is providing a unique and valued service for the coral reef community, and focusing on the behaviors and physiology of its inhabitants may yield valuable information regarding the function of fish ponds.

Authors: Abby Nestor, Kendall Bangert, Lily Silverstein

Introduction
The objective of this monitoring project was to establish a baseline beach profile and a comparison of the varying current speeds in and around the perimeter of the Paea Lagoon fish pond. The expected outcome was a higher beach profile on the inside of the south wall due to sediment accumulation resulting from the current that flows south to north. The bathymetry of the beach from the back wall of the property to the back wall of the fish pond was mapped using cross-shore transects along the inside and outside of the pond walls and in the center of the pond. The current speeds were measured in these same areas to evaluate the possible influence of the current and the sediment accumulation it causes on the bathymetry of the beach.

Methods
To create a profile of the beach's changing elevation, 5 cross-shore transects were used: 1 transect 1 meter from the outside of the south wall, 1 transect 1 meter from the inside of the south wall, 1 transect 1 meter from the outside of the north wall, 1 transect 1 meter from the inside of the north wall, and 1 transect down the center of the pond. Along the transects, any change in the slope of the beach was measured using the Emery Method, which uses two rods, each with a marker noting the eye level of the observer, a tape measure to measure the distance between the two rods, and a protractor apparatus to measure the change in angle of the slope. To begin, the 0 m point was defined as the apex of the angle at the base of the back wall under the fourth diving board from the stairs. For each transect, the distance between the 0 m point and the starting point was measured and recorded using the two marked rods and a tape measure. One rod was placed at the 0 m point and one rod was placed at the starting point of the transect, which was at the back wall of the house. The distance between the two walls was measured using a tape measure. The change in angle between the two points was also measured and recorded using an apparatus made of a protractor with a straw taped parallel to the flat side and a string tied through the hole of the protractor with a weight attached to the end. The string fell along the 90 degree mark when the protractor was held flat side up. The protractor was held flat side up at the marker point on the rod at the starting point and the observer looked through the straw, shifting the end of the straw on the protractor to point up or down until the marker on the rod at the 0 m point was in view. A second observer recorded the angle at which the string fell on the protractor in relation to the 90 degree line. The difference between this measured angle and 90 degrees is the change in angle between the 0 m point and the starting point. The rod at the starting point was kept in place, while the team member holding the rod at the 0 m point moved the rod to the point directly before the first change in the slope of the beach that occurs directly in front of the rod at the starting point. The process used to measure the distance between the 0 m point and the starting point was repeated between the starting point and the point directly before the first change in slope. The same technique used to measure the change in the slope of the beach between the 0 m point and the starting point was also used to measure the slope of the beach between the starting point and the point before the first change in slope. The rod at the starting point was then moved to the point directly before the next change in slope, and the techniques for measuring the distance between the rods and the slope of the beach between the two rods was used again. This process is repeated for each change in slope until the back wall of the fish pond is reached.

The function tan (θ) = H/D was used to solve for the change in height (H) between each change in slope, using the angle of the slope of the beach measured using the protractor (θ) and the distance between the two rods (D). The cumulative height was calculated for each of the 5 transects and graphed with the cumulative distance from the starting point.

To measure the current speed, 10 points were first chosen in and around the fish pond where a tape measure, buoy, and stopwatch were used to record how many seconds it took the buoy to travel a given distance. One point was 5.5 m from the shoreline, 1 m outside of the north wall, one point was 10.5 m from the shoreline, 1 m outside of the north wall, one point was 5.5 from the shoreline, 1 m inside of the north wall, and one point was 10.5 m from the shoreline, 1 m inside of the north wall. On the south wall, 4 points with these same distances from the shoreline and the wall as used for the north Wall were chosen as well. The last 2 points were 5.5 m from the shoreline, directly down the middle of the pond, and 10.5 m from the shoreline directly down the middle of the pond. At each point, two team members held each end of a tape measure and one of these two team members dropped a buoy at the end of the tape measurer at which they stood. A 1 m buffer was used to allow the buoy to reach a constant speed, and once the buoy traveled 1 m, a third team member started a stop watch and stopped the stop watch once the buoy traveled a given distance. For the 4 points outside of the pond, a distance of 5 m was used and for the 6 points inside of the pond, a distance of 3 m was used. This was repeated 5 times at each of the 10 points, and the average time it took to travel the given distance was calculated. The amount of meters traveled was divided by the average time to calculate the average current speed in m/s at each chosen point.

Results
Figure 1. Beach profiles of 1 meter to the right or left of the respective wall and the center of the fish pond.
https://docs.google.com/document/d/18pQvFWGDjtg89jIlTOwIRssvCENwRNFxEPDVx1oRX_w/edit?usp=sharing

The outside of the south wall had the lowest beach profile of all 5 sites. The shoreline was reached at around 9.27 meters with a total distance of 34.6 meters. As seen in Figure 1, this profile lies significantly below the other sites sampled and reaches its steepest slope at 22.31 meters. It briefly increases in height before reaching the back wall of the pond. This profile had an overall slope of -0.115. This was the steepest slope of all sites.
The profile of the inside of the south wall was a total of 37.89 meters in length. The bathymetry showed a gradual decline in height with a significant increase in slope steepness at 32.46 meters. The profile has an overall slope of -0.0908.
The middle of the pond had a fairly high profile that was 35.5 m in length. The slope fluctuated between increasing and decreasing steepness until 17.73 m where it significantly increased in steepness. The profile had an overall slope of -0.0903, which is similar to that of the inside of the south wall.
The inside of the north wall had the highest profile overall and was 38.67 m in length. The slope decreased before flattening out and increasing slightly at 3.65 m. The slope then decreased gradually before a slight rise in elevation approximately 5.89 meters from the wall where there is a patch of rocky substrate. The overall slope was -0.0911, similar to that of the south wall and middle of the pond.
The profile of the outside of the north wall had a length of 35.37 m. The slope of the beach decreased gradually before flattening out at ~21 m and then fluctuated in steepness for the rest of the profile, with a final increase 2.11 away from the back wall where a rocky portion lies.
The overall slope was -0.0996.

Figure 2. The current speed is measured along the outside and inside of the walls and middle of the fish pond within two distances from the shoreline.
https://docs.google.com/document/d/1A05Mk31mAPxufpbUG6dC-EWkxcY2xQxDEcnoFefgBZs/edit?usp=sharing

Figure 3. The standard deviation of each measured current speed with a gradient depicting highest to lowest deviation value.
https://docs.google.com/document/d/1AlyQYfcdaSQjspsW31pykuVYXOHchfmQ0UlB-1LQC0g/edit?usp=sharing

As clear in Figure 2, current speed was relatively consistent with a range of 0.118-0.267 m/s. The slowest speed occurred 5.5 m from the shoreline on the inside of the south wall. The fastest speed occurred 10.5 m from the shoreline on the inside of the south wall. Figure 3 displays the standard deviations for each current speed. The lowest standard deviation was 0.025 and occurred 5.5 m from the shoreline on the outside of the south wall. The highest standard deviation was 0.125 and occurred 5.5 m from the shoreline on the inside of the south wall.

Discussion
Due to constantly changing currents, a correlation cannot be determined from this limited data set. The beach profiles and current speeds serve as a baseline to build upon in future surveys. The overall slopes of the profiles were relatively consistent between the five sites. The outside of the south wall had the steepest overall slope of -0.115 indicating a lack of sediment accumulation. This outcome was expected due to the current flowing south to north which pushes sediment over the wall to the inside, displacing sediment from the outside. The current speed complimenting this data shows small scale changes due to a heterogenous wall varying in height. The slopes of the profiles of the other sites were all relatively consistent.
The fastest current speed was 10.5 meters away from shoreline on the inside of the south wall and was 0.45 m/s faster than the outside. This was unexpected because the wall was thought to slow the current speed and therefore the speed should be higher on the outside of the south wall. These results could be explained by the changing wind speed which caused a large standard deviation of 0.125 occuring 5.5 meters away from the shoreline on that same side of the wall. Also, the tide was higher than usual so the rocks were deeper in the water which may have interfered with the usual current dynamics. As the current continues to flow northward, it would typically pick up speed due to scouring which makes the current stronger as it approaches the inside of the north wall. It loses speed when it passes through the wall resulting in a higher speed on the inside of the north wall compared to the outside of the north wall. This is shown in our results with 0.055 m/s decrease in speed.
During data collection, wind speeds varied between 2 to 4 on the Beaufort scale. This wind may have led to potential errors as in order to obtain an accurate angle measurement, the string needed to hang straight down and it was often blown by the wind. Furthermore, these wind variations caused fluctuations in speed at which the buoy traveled throughout each trial, leading to large deviations between measured current speeds at given location. Lastly, current speeds were measured at different distances from the inside and outside of the fish pond to reduce overlapping currents.

Proposal for Future Studies
In future studies, the accuracy would be improved with the survey being performed over several days, in differing conditions, and over different seasons to account for temporal changes in this fish pond’s bathymetry. Although potential errors have been accounted for in our data, it can be assumed that improvements can be made in order to effectively compare changes in these beach profiles. Substrate type in different areas of the pond may also be compared to its current speed.

Metadata
Beach Profile Data:
31 July, 2024
1 PM- 6 PM
Beaufort 4
Cloud Cover 90%

Current Speed Data:
1 August, 2024
11 AM-2 PM
Beaufort 2-4
Cloud Cover 65%

Authors: Maria Miller, Alex Lombardi, Diya Sterling
Survey Dates: July 31 - August 1
Location: Pa'ea Lagoon, Tahiti Nui, French Polynesia

Introduction

Wildlands Studies research teams have surveyed the Pā’ea Lagoon Aua i’a over Winter and Spring seasons for the past year to document substrate variety and abundance. Throughout this time, changes in substrate have been observed, and have been used as a basis for future observations. Continuing this research we intend to focus specifically on mineral content to thoroughly represent the mineral cover within the fish pond.

As Tahiti enters the winter season, new data is significant in determining if there is a correlation between dominant substrate groups and their location within the fish pond, as opposed to other seasons and data collections. As our methods and focus vary from past surveys, we will only be comparing their inside substrate data, and not focusing on specific species of algae, but instead categorizing algae as a substrate type.
Our client is most interested in understanding the collection of sand around the North and South walls, and a general mapping of where different substrates are located within the fish pond. In order to develop a hypothesis as to why the collection of sand is allocated, it is necessary to first get a strong understanding of where these collections of sand are located along the walls. For the purpose of this survey, we will be using the term channel to describe the openings in the north and south rock walls that are likely developed from erosion. We hypothesize that these channels in the rocks are resulting in the deposition of sand along the walls. Overall, our study aims to determine mineral substrate cover of the fish pond, with a focus on sediment deposition along the North and South walls.

Methods

The materials used include a transect that reached 20 meters, snorkel gear with fins, neoprene socks, an underwater slate, one 50 centimeter by 50 centimeter quadrant, a camera, and 24 plastic cups labeled by quadrant points. Before the survey commenced, a preliminary survey was conducted to get a general idea of the surface area and to determine the best way to separate transects.
We began our survey by allocating roles between three group members. Two members held the transect, one on each end, and one member swam along the transect surveying the substrate cover within a 50 centimeter by 50 centimeter quadrant. We measured the dimensions of the fishpond and found it to be a 15.25 meter by 15.25 meter area. With this, cross-shore transects were separated by 5 meters from the inside part of both the North and South walls, creating two transects inside of the pond. Three more transect areas were placed at the center of the perimeter wall of the pond. Two of these were cross-shore along the North and South walls. The West wall had a longshore transect to close off our sampling universe within the fishpond.
At each transect, a quadrant was placed every 3 meters five times, starting at 0 meters, with the top left of the quadrant placed on each point on the left side of the transect. For the two transects inside the pond, we only surveyed the left side of the transect. For the transects lining the perimeter, we surveyed both the left and right side of the transects to gain insight on the immediate outside of the pond to fulfill our client’s interest. At each site, sand portions were lightly dusted through to uncover the possibility of different sized sand particles under the first layer.
For the transects inside the pond, once the left side was surveyed at all five points, the swimmer went back to shore to immediately take a picture of the data gathered and switch out the slate and quadrant for 5 plastic cups labeled for each survey point. Once again moving every 3 meters starting at 0 meters, the swimmer scooped the top layer of sand at each of the five points. For the perimeter transects, this was only done on the inner wall at each of the five points. Once we completed the entire survey, two swimmers were designated to get 2 samples of the top layer of sand right outside of the North and South walls of the fishpond where the large piles of white sand were found in order to more deeply analyze the sediment per request of our client.
For data analysis, we used a Google Sheet to create a table for each of the transects and substrate types which included fine white sand, fine black sand, coarse white sand, coarse black sand, rubble, rock, artificial stone, algae, live coral, and dead coral. We differentiated fine and coarse sand by individual particle size, provided by the spring research group. The spring research group concluded that fine sand was particles less than 1 mm, while coarse sand was particles over 1 mm on average. We had overlapping substrate cover, so each area summed up to a percentage over 100%. From this, we were able to make pie charts for each of the transects which used ratios for each of our percentages so that they could be a total of 100%. We then created a second table that took the average coverage of all the substrate types overall transects and found the standard deviations for each group. A pie chart was formed out of this table as well. Once this data was analyzed, a map was formulated showing each of the dominant substrate types in each quadrant area to encapsulate the variation across the fishpond floor for our client.

Results
Figures and Data: https://docs.google.com/spreadsheets/d/1aaYnemKM8PBG3YQlgV00L5wFx-vuUwom1tuDsJfMhdA/edit

Discussion

An overall average of 18.4% of fine black sand and 17.5% white fine sand cover dominated the sampling universe. Fine and coarse grain (white/black) sand was the main type of substrate cover throughout the fish pond. Our client was specifically interested in the piles of fine-grain white sand accumulating on both North and South walls. It was unclear as to how these piles occur, postulating whether it was current direction, biological erosion, or holes in the fish pond wall causing sand to pile up in these two areas. Upon further observations, our team discovered that these substrate piles consisted of a sediment deposition of fine black sand on the outer south wall, with fine white sand on the inner south wall. Fine white sand dominated the outer north wall, and fine black sand dominated the inner north wall. These findings may suggest that waves are being refracted as they travel through the North and South walls, accumulating fine black sand on the South sides of the walls and depositing fine white sand on the opposite side.
Though we had different methods for surveying and conducting calculations, we were still able to compare our data with the Spring data through the dominant substrate found inside the fishpond and directly outside. In the Spring, it was found that coarse sand was the dominant substrate inside of the pond and fine sand was dominant outside of the pond. For our current data conducted this Winter, the dominant substrate found both inside the pond and directly outside the North and South walls was fine white sand. This differs between the seasons. Despite the Spring group not including their survey conditions, we can infer that winds are stronger during the Winter in Tahiti, likely increasing the level of erosion and sifting sand substrate in the channel regions of the fishpond. Colder temperatures may also increase nutrients in the water attracting more bioeroders and increasing algae composition. Halimeda algae also disintegrates fairly quickly and adds to the fine white sand substrate content, as mentioned by our client. We suggest that future research projects should collaborate with another team observing Bathymetry to get a deeper understanding as to why the sediment depostion and wave current sieves out the white and black sand this particular way in the channel. Something to note is the wave direction was traveling from the South, with some wave interference from strong winds possibly impacting these filtrations.

Areas for Improvement/Suggestions to Future Groups:

For this survey, we separated algae substrate from mineral substrate to ensure a further in-depth analysis of each substrate cover as suggested by past groups. This worked very well for us, so we suggest continuing this in future surveys. We also adjusted the methods by using systematic sampling along transects instead of random coordinates to gain a more accurate area cover and standardization.
We did have areas for improvement. Once we analyzed our data, we realized some points in the fishpond weren’t accounted for, so we recommend allocating transects in a way that reaches all corners of the fishpond. For example, the entrance to the fishpond was missed in our data and could be significant when looking at the channel on the sides of the pond. For samples taken, it is important to ensure saving them for future further analysis done by the client. Also, ensure a scale is included for comparison in any photos taken of the sand samples for a better visual of the differing sand sizes and context. During the survey, we faced some opportunities for human error. When we entered the water, the Beaufort scale reached a 2. While in the water, we found the Beaufort scale changed to a 4 and stayed this way until we exited the water. In combination with the Southern winds, this created difficulties as the transect moved with the strong current and the quadrant placed had to be held firmly to keep it from drifting. There is also the likely occurrence of bias due to having only one person surveying the substrate cover and only having the ability to use human vision which is limited. For the future, we recommend having multiple swimmers surveying the quadrants to ensure a lower likeliness of bias. We were unable to do this due to time constraints and limited participants.

Conclusion

Our studies show the collections of sand around the North and South walls were a result of sediment deposition from filtration through the fish pond walls. We designed a general map of substrate cover in the fish pond to visually display the variation of substrate cover, as well as the location of the sand piles in the channel. The North wall accumulated fine black sand on the inside of the wall, with fine white sand on the outside. The South wall had accumulated fine black sand on the outer wall, with fine white sand on the inside. We suggest that this pattern of accumulation may be due to wave refraction as the current hits different parts of the wall, and the influence of the 1m hole in the West wall causing a stronger current within the pond. Further studies need to focus on the North and South wall channels to analyze the sediment deposition and mineral content in order to predict future erosion patterns of the fish pond substrate. This could also raise the question of how this impacts species abundance and behavior in the fishpond.

Authors: Maya Rink, Taylor Byrd, Sarah-Rose Nicolson, and Jayden Kaptein
Survey Dates: July 31-August 1, 2024
Location: Pa’ea Lagoon, Tahiti Nui, French Polynesia

Algae Research of Pā’ea Fish Pond - French Polynesia Summer 2024

Authors: Maya Rink, Sarah Nicolson, Jadyn Kaptein, Taylor Byrd

Survey Dates: July 31 - August 1

Locations: Pa’ea Lagoon, Tahiti Nui, French Polynesia

INTRODUCTION

This survey studied the types of algae species inside of and on the rock walls of the Paea Lagoon Auai’a fish pond in Pā’ea, Tahiti, French Polynesia on August 1st, 2024. This type of fish pond was historically used by Polynesians to collect fish to eat within its walls (a rock barrier), however, the practice fell out after French colonization and large-scale fishing became more widespread.

The Paea Lagoon Auai’a fish pond is one of the original historical fish ponds, however it underwent restoration four years ago, and is now only used for scientific observation, not for harvesting fish.

The team has been hired by a private client to identify all of the types of algae observed in the fish pond and on all sides of the rock barrier. The barrier is a structure of large uneven rocks. Currently, the client knows there is some algae present in the fish pond, especially along the walls, but is uncertain of the species richness and percent cover of algae present.

This research is building upon previous Wildland Studies programs’ projects from August 2023 and May 2024 who also surveyed algae presence within the pond. This comparison will answer the given research question: how has the richness and percent cover of algae in the Paea Lagoon Auai’a fish pond changed over time since Summer 2023. The team will use the previously collected data to develop a trend analysis to address this question.

The research will differ from previous surveys as it will emphasize the development of a complete species list of algae present in the fish pond, where previous surveys have grouped their data by agal families.

Furthermore, the surveyors collaborated with another research team that is analyzing the substrate present in the same fish pond. Our teams will compare algae relationships with substrate cover.

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METHODS

Fish Pond Survey
The team began by taking a preliminary survey of the area. Two swimmers measured the fish pond and scanned the area to gauge an understanding of the quantity and general types of algae that would be studied.

The 15.25m*15.25m fish pond was then divided into five transects. Three transects were used to study the fish pond’s rock barrier walls (Transect 1, 4, and 5). The other two were dedicated to the inner pond (Transect 2 and 3). Each cross-shore transect was spaced 5.1m apart. The transects were then split into five survey points which occurred every three meters. The quadrat method was utilized to conduct the survey. Starting at 0m, a 50*50cm quadrat was placed with its top right corner (when facing the ocean) on the survey point, with the first quadrat measuring the first 50cm of sand following the shore.

The same transect lines as the substrate research group type were used to obtain complementary data.

The method for the rock barrier and surrounding area was slightly altered to obtain more representative data of the algae cover. Two quadrats were used at each specified marker on the transect. One quadrat was used from the center of the rock barrier to the left side, and the other quadrat was used from the center of the rock barrier to the right side. The quadrat’s length was extended an extra 25 cm (making the total length 75 cm) to include the area surrounding the wall.

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Start: 8/1/2024, 12:15pm, beaufort 2, 23°C, partly cloudy 30%, wind blowing from SE.
End: 8/1/2024 4:00pm, beaufort 4, 22°C, partly cloudy 40%, wind blowing from SE.

The four person team assigned two people to hold the transects and the other two to be swimmers, collecting the data using quadrats. The first observation of each species of algae was sampled and stored in a numbered plastic bag to be studied and identified after the survey. Ten bags of samples were collected, some of which were revealed to contain repeat species.

Beach Survey
From 2:50pm to 3:00pm, the team completed a terrestrial survey, sampling the 15.5m of beach adjacent to the fish pond to study the species richness of washed up algae. This survey was done opportunistically with all four team members collecting as many unique species of algae as possible.

Following the surveys, the team separated the samples to identify each species. A microscope was utilized to closely observe smaller species of algae. Identification was completed through the use of an algae identification book: Algae of French Polynesia (Payri et al., 2000).

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RESULTS

see Figure 2. Species Index: https://docs.google.com/document/d/e/2PACX-1vT4dP08Q0ozwChf3HqfIb2_oDwA5l-xTakvLPqUiBLrflnHBzW9SEa3cL-wt3aEOrXBTR68FB-MOjuX/pub

see Data Set: https://docs.google.com/spreadsheets/d/1lgfq4BT0JQU3NYPJq31JUx_b4gDFCwIZgzQo0q153DM/edit?gid=0#gid=0

see Figure 4. Percent Coverage Comparison of Algal Species: https://docs.google.com/document/d/e/2PACX-1vT4dP08Q0ozwChf3HqfIb2_oDwA5l-xTakvLPqUiBLrflnHBzW9SEa3cL-wt3aEOrXBTR68FB-MOjuX/pub

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INTERPRETATIONS

When examining the collected data from various transects, several key trends and observations emerged:

1. Species Distribution and Dominance:
   The accumulation of the data collected found 15 different species in total ranging between family rhodophyta, chlorophyta, and paethaedae. The survey found the dominant algal species in the fish pond to be Microdictyon umbilicatum, a type of microalgae or turf, representing 68.6% of all algal species.

When comparing algal presence across all transects, there is a clear increase in abundance along the walls as compared to the inner pond, represented by transect two and three. Here, the substrate consists of artificial rock. Turf algae, specifically Microdictyon umbilicatum, was the most prevalent species on these rocks. This suggests a positive correlation between the artificial rock substrate and the abundance of turf algae, indicating that substrate type significantly influences algae distribution.

When comparing algal presence on the inner and outer sides of the walls, percent cover is consistently higher on the inner sides of the wall. This could be alluded to several potential reasons including possible increased herbivory by adult fish on the outside of the pond or rougher condition on the outer walls preventing algae from growing. More research should be done to make a conclusion.

Algae coverage was compared with another research group focusing on substrate type using two of the same transects, 2 and 3. Both teams also collected data from the area surrounding the pond’s walls (transect 1, 4, and 5). The quadrats within the fish pond that exhibited the highest algae coverage primarily contained white fine sand and black fine sand.

Conversely, the data collected by the substrate group indicated that the primary substrate on the walls, where algae coverage was the most abundant, consisted of artificial rock, with some white and black fine sand present.

1. Comparison with Historical Data

In previous years, data was collected on the general algae coverage in the fish pond quadrats. During the Summer 2023 assessment, the algae coverage was found to be 28% with a standard deviation of 0.2614, with seven genuses observed. In Spring 2024, the average algae coverage dropped to 23.87% mean coverage with a standard deviation of 0.12572084, with five species observed. These previous studies examined quadrants both on the walls of the fish pond and within the pond itself. Our data from this year revealed a 27% algae coverage in the fish pond our standard deviation was 0.1144220727.

Our Summer 2024 findings identified a greater variety of algae types which originally totalled seven genuses. We identified 15 algae species, with 13 total genus, indicating potential yearly variations in algae diversity. However, more data should be collected over an extended period of time to make this conclusion.

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DISCUSSION

Potential for Error
During the team's trials, several errors were encountered. Two transects broke, affecting the overall trial duration due to the additional time needed to replace them. Strong currents impacted the linearity of the transect lines.

Human error, including misidentification is also possible to have occurred. Additionally, issues with gear, such as leaking snorkels and masks, should be noted, potentially affecting species observation. It's important to highlight, also, that the identification book, Algae of French Polynesia, was published in 2000, meaning there could have been revisions to the taxonomy of the algae since its release.

In addition, some of the algae collected required a microscope for identification. It was not possible to use a microscope for every site in the field, so microalgae and germlings of macroalgae could have possibly been looked over.

For future studies, the team recommends using high-quality transects and gear capable of withstanding unexpected weather, given the cold and windy conditions encountered during the trials. Additionally, conducting more trials would make the data even more accurate.