Bio 412 - Marine Benthic Biota Survey

Sheung Ying Ting
Bio 412

Lab 2

INTRODUCTION

Scientists always collect data in the field which could mean underwater, in a cave, on a reef, or in a forest. There are two standardized ways to collect ecological information from the field which are transect sampling and quadrat sampling. These methods may able to provide more accurate data compare to the other methods which are random sampling or simply guessing. However, the random sampling and simply guessing methods are easier, and take less time to do so, therefore, it is a good way to use those methods to help us in estimation and comparison
Transect is simply a line we stretch oven an study area. This line must have regular measurement marked off, like a tape measure, and is held straight and still. Quadrat counted within a grid. The grid must have a standard size for each transect.

METHODS

There are seven points within the three study areas which located parallel to the coastline on the Clissold’s beach. On all transect lines, 10 quadrats, each 1.0 m x 0.6 m, were defined at random points along the 33 ft. transect line. Each permanent quadrat was photographed (see appendix 1) by using an underwater camera.  Each photograph was separately labeled to designate the location of each frame within each transect. Photographs were taken using high resolution digital photography. In the laboratory, accurate estimates of the benthic cover of biota and substrata were performed using the software Coral Point Count with Excel Extensions (Kohler 2006) overlaying a 10 x 20 grid to divide the photographs into 200 equal sized segments and biota and substrate type at each point were identified.

RESULTS

From the data sheet (raw data), we included stony corals, coralline algae, turf algae, macroalgae, and dead coral with algae.  All were present in very small numbers especially for the stony corals which only covered less than 11% of the study area biota.  The area mainly covered by sand, coral rubble, and rubble.

The two most dominant corals were Porities lobata and Poritis compressa which were present on most of the transects.  Other corals present were Pocillopora meandrina, Pocillopora damicornis, Pocillapora eydouxi, and Montipora capitata which are in small amount. 

Porities lobata was abundant within all areas. Poritis compressa was abundant in mostly in area 1 and 2.  

Table 1 shows a comparison of the percent coral cover in each transect area. Area 2 was the highest in total coral cover (5.93%) due mostly to its abundant P. lobata and P. compressa. Area 1 was mainly cover by P. lobata, the overall coral cover was 2.51%. The lowest overall coral cover (1.52%) was observed at area 3, the northernmost site and increased moving southward. The highest P.lobata cover was find at area 1- 1B (9.5 %) then in area 2 -4B (5.01%) and 4A (4.75%).