06 de agosto de 2022

Paea Lagoon Aua i'a Fish Pond Monitoring, Group 3: Benthic Cover, Tahiti, FP, 2022

METHODS:
Substrate cover of the fish pond was measured using a 1 square meter quadrat for 20 preferentially sampled areas within the fish pond and 1 meter surrounding the outside perimeter of the fish pond walls. 20 total quadrats were taken within this sampling universe. Quadrat placement was measured on a grid of the fish pond, where we measured the quadrat distance from the southern most corner of the rock fish pond closest to the house wall (AKA the bottom left corner of the fish pond). However, for calculating quadrat distance considering the 1 meter extension of our sampling universe beyond the rock wall, we measured 1 meter south from the southern corner part to match the end of our sampling universe. We considered this spot the "origin" or starting point of all measurements at 0 meters in width and height. Quadrat placement was measured on the grid for replicability of future groups including 20 preferentially chosen placements. Substrate cover categories included coral, sand, coral rock, river rock, turf algae, and macro algae. The mean and standard deviation was calculated for each substrate category.

The quadrat locations are as follows including formatting of (Height, Width) in meters from the starting point of (0,0). These measurements are to the bottom left corner of the quadrat. Coordinates of our quadrats were: (5, 4.6), (7.5, 8.7), (13.3, 6.1), (10.8, 15.2), (14.1, 15.4), (9.2, 12.1), (2.8, 2.5), (5.5, 11.4), (8.1, 17.9), (15.6, 14.1), (4.4, 6.1), (7.2, 5.3), (9.7, 6.9), (14.4, 6.2), (13.8, 1), (7.1, 1.1), (12.5, 19), (11.3, 15.2), (5.6, 8.9), (3.1, 12.4)

For each quadrat two surveyors estimated the percent coverage for each quadrat peramater. The parameters evaluated were coral, sand, coral rock,river rock, turf algae, and macro algae cover. After field data collection, we calcuated the average percentages of each substrate between the two individual observations of the same quadrat to eliminate bias. Using these 20 average points for each type of substrate (coral, sand, coral rock, river rock, turf algae, and macro algae) we calculated the mean and standard deviation (S.D.) for each substrate as shared below.

DATA:
Coral: Mean = 10.125% and S.D. = 0.26
Sand: Mean = 49.425% and S.D. = 0.27
Coral Rock: Mean = 1.25% and S.D. = .028
River Rock: Mean = 16.35% and S.D. = 0.16
Turf Algae: Mean = 27.25% and S.D.= 0.20
Macro Algae: Mean = 1.8% and S.D. = 0.14

Based on these percentages the greatest to least percentages of substrate cover within the pond and 1 meter on the outside perimeter of the pond was sand, turf algae, river rock, coral, macro algae, and coral rock.

Publicado em 06 de agosto de 2022, 01:09 AM por langzi langzi | 0 comentários | Deixar um comentário

Paea Lagoon Aua i'a Fish Pond Monitoring, Group 2: Fish Biodiversity and Behavior Patterns, Tahiti, FP, 2022

METHODS:

For this project, we separated the fish pond into three sections; the interior of the pond, a four-meter buffer area surrounding the exterior wall, and further out into the lagoon. We split the interior pond and exterior perimeter into three sections, one for each person to observe, and for 20 minutes in each section we floated around and observed the behavior and relative abundance of 22 fish families that are frequently observed at and around the pond. To do this, we tallied how many fish of each family we saw and organized their behavior into 10 behavioral categories (A- feeding on algae, B- feeding on the substrate, C-feeding on coral, D- hiding in rocks, E- juvenile fish taking refuge, F- freely swimming with no distinguishable pattern, G- other behavior and provide comments, H-hunting, and T- protecting their territories). When we observed the outer lagoon, we focused on examining behaviors that we did not see in the pond rather than counting for fish individuals.

RESULTS:
Our results revealed some of the more common behavioral patterns observed inside and on the exterior of the wall:

  • Damselfishes were the most abundant family noted and were almost always found hiding inside of the wall rocks on the inside and outside of the pond. They exhibited typical territorial behavior and often chased other fish families away. Outside in the outer lagoon, we did not see a high abundance of damselfish due to the large amount of macroalgae, showing that the ponds provide an ideal habitat for this family.
  • In the inner and outer perimeter of the fish pond we observed juveniles from surgeonfish, butterflyfish, and triggerfish families. They were concentrated in smaller rocks that were not a part of the rock wall. None were sighted beyond the four-meter buffer zone, highlighting that the fish pond may serve as a nursery for a variety of families. In order to better facilitate the fish pond as a nursery, we suggest increasing the amount of smaller rocks within the center of the pond to provide this preferred habitat.
  • As a general pattern, we primarily observed families feeding on the benthic substrate, rather than coral or algae. We noted a lower density of herbivores than we have seen on other reefs. For example, we counted no rabbitfish and a lower abundance of surgeonfish.
  • We observed snappers and prey fish hiding in the rocks, which might indicate that the fish pond walls serve as a refuge for these fish.
Publicado em 06 de agosto de 2022, 12:47 AM por langzi langzi | 0 comentários | Deixar um comentário

Paea Lagoon Aua i'a Fish Pond Monitoring, Group 1: Invertebrate Abundance, Tahiti, FP, 2022

INVERTEBRATE SURVEY METHODS
To survey invertebrates in the fish pond, we divided the area into three sections: the interior wall, interior floor, and exterior wall. We recorded every invertebrate species we observed, grouping them by families.

To measure abundance on the interior wall, 3 surveyors swam within a meter inward from the base of the wall, recording number of individuals seen on and around the wall.

To measure abundance in the interior of the pond, we laid transects every two meters starting from the southeast end, conducting swath surveys. We avoided the area a meter from the interior wall. Each of six total swaths was two meters wide and 14 meters long. Two team members held two transect tapes to mark the area of the swath while the other team member swam up and down the swath area counting each individual invertebrate.

To survey the exterior wall our team of 3 swam along the entirety of the outside of the wall and counted invertebrates on the rocks, then turned around and counted invertebrates on the sand extending two meters from the wall on the way back.

Additionally, we used a ScubaJet to count Crown of Thorns Starfish across three transects extending west about 25 meters from the outer edge of the pond, one on either corner and one in the middle.

Families we observed were snails, hermit crabs, crabs, urchins, sea cucumbers, worms, shrimp, and sea stars. We also recorded holes and mounds that indicated the presence of invertebrates.

DATA
Interior Floor:

  • 38 individuals counted
  • Average transect had 6.3 invertebrates (with a standard deviation of 1.82)

Interior Perimeter:

  • Average of all surveyor's data was 38 invertebrates (with a standard deviation of 2.42)
  • Most abundant species was worms, with an average between observers of 17 individuals

Exterior Perimeter:

  • Average of all surveyor's data was 58 invertebrates (with a standard deviation of 14.63)
  • Most abundant species was hermit crabs, with the average among observers 10. This excludes holes and mounds

Crown of Thorns:

  • Zero individuals observed
Publicado em 06 de agosto de 2022, 12:02 AM por langzi langzi | 0 comentários | Deixar um comentário

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