Eelgrass, sea stars, and little oysters

Today started with a beautiful morning drive to false bay. The tide was lower today and the wind less intrusive so we were able to compleat all the work planned. Fieldwork was led by Maya Groner and Drew Harvell.

1. Prevelence of disease in mid level plot (n=10 2nd longest blades removed each 10 meter from 0-50). The blades were measured and level of disease assessed back in the lab.

2. Collected Zostera marina shoots for Maya’s experiment.

3. Assessed mid level plot density (# plants on frame at 0, 25, and 50 meters).

3. Located the culling experiment plots and removed blades from center of each. There was noticeably more smithora present at this plot compared to the one we visited yesterday on Shaw. At this site there were 2 sets of plots.

Plot 1: Control1-cull1-cull2-control2, Plot 2: control1-cull1-cull2-control2

The False Bay Zostera marina bed.

The False Bay Zostera marina bed. Tide is not out yet so moat of the eelgrass is underwater still. 

Working hard to get all the culling experiment plots done before the tide comes in!

Working hard to get all the culling experiment plots done before the tide comes in!

Example of clear laby lesion (right) and a lesion that is not clearly laby (left). It is best to be conservative and only count lesions where there is black visible next to the light tissue.

Example of clear laby lesion (right) and a lesion that is not clearly laby (left). It is best to be conservative and only count lesions where there is black visible next to the light tissue.

Trying to locate our culling plots underwater.

Trying to locate our culling plots underwater.

Since the level of disease increases with blade age it is important to always choose the second longer blade so results ads consistent.

Since the level of disease increases with blade age it is important to always choose the second longer blade so results ads consistent.

The laby infection displays as a light patch edged by black, necrotic tissues where the plants defense has responded to the infection.

The laby infection displays as a light patch edged by black, necrotic tissues where the plants defense has responded to the infection.

Measuring and scoring disease stage of Zostera marina blades in lab.

Measuring and scoring disease stage of Zostera marina blades in lab.

Today I also started work on a pilot study to determine if bivales filter the sea star wasting disease pathogen out of the water.

1. Juvanile oysters (1-3 cm) were out planted at Eastsound Dock (high SSWD) and Cresent Bay (low SSWD). N=10 were left for duration of the low tide and 10 left for 24 hours. Oysters were placed on mesh bags just below the surface of the water, next to where pisaster are found with disease. Many thanks the Amy Henry and Natalie Rivlin for thier help placing the bags at Orcas Island. They returned at 6 pm with the first set of oysters, which I then removed from shell, measured, weighed wet tissue, and froze at -80.

Oysters in mesh bags prepared to be placed at the field site.

Oysters in mesh bags prepared to be placed at the field site.

Cute baby oysters courtesy of Colleen Burge!

Cute baby oysters courtesy of Colleen Burge!

SSWD/oyster filtering data collection plan.

SSWD/oyster filtering data collection plan.

I set the experiment up in the ocean acidification lab. It will only run a few days but if the data turns out interesting may be the basis of a larger study.

Oyster exposure to SSWD conducted tanks within the OA lab so the incoming water was filtered.

Oyster exposure to SSWD conducted tanks within the OA lab so the incoming water was filtered.

I will include more on the experimental design tomorrow. Basic set up: 3 control (no stars) and 3 experiment tanks (symptomatic stars),  40 oysters in each bag, 10 oysters removed at each of 4 time points after which experiment is ended. The field and lab data will then be looked at with disease prevelence at the field sites and data from clams.

Tomorrow I will be heading over to Orcas Island to retrieve the remaining oysters (24 hour exposire) and out planting a bag at the FHL dock.

 

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