Fish and Invertebrate Species Richness - Fish Pond Monitoring FP 2024

Authors: Payton Curley, Evan Gray, Jasmine Rosado, Julianna Evinski
Introduction:
The objective of this monitoring project was to collect data on the richness of fish families and invertebrates both within and in areas surrounding the fish pond. We were tasked with creating a cumulative list of all the species found in four locations: inside the refuge, within the fish pond in general (excluding the refuge), directly outside of the fish pond’s borders, and further away from the pond in the reef area. Species richness—or species count—in an area is important because it can be an indication of biodiversity. We analyzed species richness in the fishpond and made comparisons to the outside, calculating the number of species per square meter for every area in the process. This information can be used to compare to past years and analyze changes in diversity. We can draw conclusions about overall health and activity of the fishpond, as well as changes over time based off this information. The monitoring of this pond officially began 2 years ago and our group is excited to contribute to this monitoring project.

Methods:
Our areas of focus consisted of inside the fish pond, the exterior of the fishpond wall, the outer coral reef, and the new refuge in the fishpond. For the inside of the fishpond we decided to conduct a preliminary simple floating survey to get a gauge of what species we should be looking for. The next day we decided to use the transect beam method to quantify the number of species in the pond. We used 3 transects--one for each wall--each 15 meters long. We began by measuring 1 meter away, perpendicular to the wall, to establish the start point on the transect and staked it down in the sand with a rock. A researcher then ran it parallel to the wall and swam an extra few meters past the other end so as not to bother fish directly in the 15 meter survey area. After waiting 2 minutes, another researcher would then swim along the transect, recording any pelagic fish seen 1 meter on each side of the transect below, covering a total of 30 square meters per transect. After swimming the length of the transect, the researcher would then wait another 2 minutes and then swim back over the transect, this time recording benthic fish and invertebrates.
To survey the outer border of the fish pond, we used the same method, instead measuring 1 meter away from each wall on the outside of the pond. We then ran each 15 meter transect parallel to the wall and recorded pelagic and benthic species, as well as invertebrates.
To survey the outer reef away from the fish pond, we used three different areas. The first area we measured was 15 meters away from the left wall of the fishpond. We laid a transect out parallel to the wall, repeating the same methods to measure fish species. We then measured 15 meters away from the border wall and laid out another transect parallel to the fishpond and repeated the survey methods. We then measured 15 meters away from the right wall and laid out another transect, repeating the same methods for measuring fish species.
We also measured the fish species in the newly built refuge. One researcher started a 10 minute timer, watched the fish swimming in and out of the rocks surrounding the refuge, and took note of the different species. After the first 10 minutes were up, the researcher then started another 10 minute timer and watched the fish that were inside the refuge and in the boulder.
In conducting this survey, there were a couple changes from the previous year's group that observed fish biodiversity. Although we used the same methods for surveying the inside of the pond and on the border of the wall, we changed the method for the outer reef survey. The previous group decided to use coordinates and do 3 transects parallel to shore at that location. We decided instead to survey 3 different locations, each parallel to one of the walls of the fishpond. We changed this because we believe that surveying different locations for the outer reef would give a more accurate depiction of the greater lagoon that the fishpond is a part of. We wanted to eliminate possible confounding variables as factors like the strength of the current and depth vary based on where you are in relation to the fishpond. This is why we decided to include two areas off the beach on either side of the fishpond as well as one further into the water from the outside wall. This way we could see how the fishpond affects the greater ecosystem.
In addition to these changes, we also decided to focus solely on species richness rather than richness and abundance due to the fact that our client was most interested in which species were present rather than the amount of individuals we saw. Another addition to our methods in comparison to the previous year was focusing on invertebrate species as well. The method that we chose for surveying fish species works for invertebrates, which our client was interested in seeing in addition to the fish species.

Results:
INSIDE
It consisted of 16 different species making up 9 families. Damsel, Soldier, Surgeon, Cardinal, Lizardfish, Wrasse, Butterfly, Trigger and Goat. The main families were Butterfly, Wrasse, and Damsel. There were also a few invertebrates in the pond that were recorded, which were burrowing urchins and cone snails.
BORDER
We found 12 species and 6 families. The families we saw were wrasse, damselfish, butterflyfish, goatfish, triggerfish, and snapper. The dominant fish families in that area were the wrasse, damselfish, and butterflyfish. On the border there were invertebrates like urchins, sea cucumbers and snails.
OUTER
We found 8 species and 6 families outside of the pond. Those families were wrasse, triggerfish, damselfish, butterflyfish, goatfish, and blenny. The dominant fish families were wrasse and damsel. The invertebrates that were seen were sea cucumbers and urchins
Species per square meter:
In the outside of the pond the fish species per sq meter is 0.267 and the family per sq meter is 0.2. The border of the fish pond species per sq meter is 0.4 and the family per sq meter is 0.2. Inside the fish pond the species per sq meter is 0.533 and the family per sq meter is 0.3.
REFUGE
The refuge has a 5.26M^2 area and the species found in the refuge were convict surgeonfish, vagabond butterflyfish, dusky gregory damselfish, scribbled rabbitfish, and shrimpgoby. The species per meter squared is 0.95.

Excel Sheet of Fish species and families in the areas we surveyed and the refuge: https://docs.google.com/file/d/1m8wKrIt85X0fUAqYR5jy4uCnl2dJ0mCe/edit?usp=docslist_api&filetype=msexcel

Graphs of the Dominant fish families in each area surveyed: https://docs.google.com/document/d/1-TLTvTTL0N2qam0O5UhaSUtxwH7bV46unkOpq7_5_dE/edit

Discussion:
After the survey, it was determined that there was a greater diversity of fish species inside the pond versus near the pond and 15 meters away from the pond. The diversity of the fish species gradually decreases as you get farther away from the pond within the area that we surveyed. This is different from last year's findings where there was a higher diversity of fish species outside the fish pond. However, it is important to note that our locations outside the fishpond were in similar depth of water to the fishpond itself, and it is possible that last year surveyed a deeper area of the lagoon which would have affected the fish species they saw. In addition to this, we saw a overall increase of families of fish in all of the sites compared to last year
Compared to previous years, this year our client was less concerned with abundance and wanted to focus more on species richness. With the list of species we have curated at the request of our client, we have categorized them into families. This can be helpful to know because we have learned previously that members of different families exhibit different behaviors and it can be telling of the nature of the ecosystem interactions between fish and their environments. Ultimately with the species list, we hoped to create a bigger picture regarding species interactions. We ended up finding there was an increase in the number of species present using the same transects inside of the fish pond as last year. This increase in species richness could be occurring because of a number of reasons, including the recent swell. Our client mentioned there had been a buildup of algae and sediment in the area, and the swell washed some of these materials out to some degree. We imagine this event cleaned up some of the area, thus increasing the health of the fish pond, bringing more species back into it. Additionally, as time goes on naturally, the fish pond will gain popularity among the fish. As the ecosystem becomes more established, more species will be drawn into the pond. When juveniles come in, this attracts bigger fish and causes a cascade effect of abundance. If conditions in this area remain the same, diversity will likely continue to increase over time. We hypothesize that if the survey was to be repeated next year, the species richness will continue to increase.
We are considering our measurements as time zero for the refuge since it was only established a few weeks ago. Our client was interested in seeing how smaller, more sheltered areas would affect the biodiversity of fish in the location. We have already noticed a variety of different species and families within the refuge and within a meter of the perimeter wall. We calculated a high species per square meter value which is telling of the importance of micro-habitats and how they foster fish biodiversity.
The limitations of our experiment mostly had to do with the physical constraints of the ocean. During our first day of data collection, the tide was low and thus the water level in the fish pond was abnormally low. Still, we stuck to our methods and continued to use the transect to allocate our two meter wide survey area. As a result, some areas were too shallow for fish to be located in–namely the left and right transects inside the fish pond which ran perpendicular to the shoreline. If we had more time to collect data, we would have waited until the tide was higher. Additionally, the current in the area was strong–especially on the first day of data collection–so the transact lines may not have been completely parallel to the walls of the fish pond. Like with our first limitation, if we were given more time, we would have waited for ideal current conditions. Our final limitation is due to the nature of observing fish in the wild. As shown in our data table, some of the species were not fully identified due to the limited amount of data we had—fully relying on memory recollection while collecting data. Therefore, both the stonefish and the shrimpgoby were identified solely by their family name instead of being more specific and identifying their species. Going forward, we would recommend to future researchers to either invest in waterproof identification guides so as to be able to identify species while still in the field or bring a camera along with them while surveying.

Posted on May 22, 2024 03:53 AM by langzi