Goose Point site growth analysis from 20250522 sampling
Goose Point growth data update
Overview
Noah O. has completed photo analysis for oyster growth at the Goose Point site from the 05/22/2026 assessment. This brings analysis of Goose Point growth up to date with the most recent assessment.
In this project, we conducted thermal and salinity hardening in 2024 and haev outplanted and monitored oysters for the past 2 years. This analyses looks at growth data collected in spring 2026.
Data and code
Data from this assessment are available on GitHub here. The code used to analyse the data is also on GitHub here.
Approach
I analyzed the growth data as I have done in past analyses detailed here.
Noah used our image analysis protocol to collect data from field images.
The analyses is conducted as follows:
- Length and width are collected from images using the protocol above
- Volume is calculated from model projections using manual length, width, and depth measurements to predict volume from length and width from photos
- Volume is analyzed as the metric of growth over time
- Models are evaluated for assumptions and outliers
- Significance of hardening effects and time are included in models with post hoc tests performed as needed
tl;dr
There are no strong differences in growth or survival due to hardening.
Results
Here is a summary of the results including the most recent time point.
Survival
There was no difference in survival for either salinity or temperature hardening, although there is a trend for higher mortality in treated oysters in both experiments.
Temperature hardening:
Kruskal-Wallis rank sum test
data: total_dead by treatment
Kruskal-Wallis chi-squared = 1.1905, df = 1, p-value = 0.2752Salinity hardening:
Kruskal-Wallis rank sum test
data: total_dead by treatment
Kruskal-Wallis chi-squared = 3.2386, df = 1, p-value = 0.07192Growth
I used a polynomial model to predict growth from length and width data. The model had a high R2 value of 0.96.
The model showed a strong linear relationship between predicted and actual volumes.
This model was then used to plot growth for each treatment.
Temperature experiment
There was a significant interaction of treatment and time in growth in oysters that went through the temperature hardening experiment.
Type III Analysis of Variance Table with Satterthwaite's method
Sum Sq Mean Sq NumDF DenDF F value Pr(>F)
treatment 43 43 1 4.0 0.0281 0.875
date 38393614 6398936 6 3690.1 4182.7838 < 2.2e-16 ***
treatment:date 101260 16877 6 3690.1 11.0317 3.194e-12 ***This was driven by significantly smaller oysters in the temperature treated group in August 2025, but there were no other differences and there is no difference at the most recent time point.
date = 20240624:
contrast estimate SE df z.ratio p.value
control - treated -2.62 7.83 Inf -0.334 0.7382
date = 20240909:
contrast estimate SE df z.ratio p.value
control - treated 3.15 7.82 Inf 0.403 0.6873
date = 20241211:
contrast estimate SE df z.ratio p.value
control - treated -4.16 7.89 Inf -0.527 0.5984
date = 20250520:
contrast estimate SE df z.ratio p.value
control - treated 6.34 7.85 Inf 0.807 0.4194
date = 20250825:
contrast estimate SE df z.ratio p.value
control - treated 23.59 8.00 Inf 2.949 0.0032
date = 20251008:
contrast estimate SE df z.ratio p.value
control - treated -14.92 8.03 Inf -1.857 0.0633
date = 20260522:
contrast estimate SE df z.ratio p.value
control - treated -2.86 8.05 Inf -0.355 0.7224Salinity experiment
There was a significant interaction of treatment and time in growth in oysters that went through the salinity hardening experiment.
Type III Analysis of Variance Table with Satterthwaite's method
Sum Sq Mean Sq NumDF DenDF F value Pr(>F)
treatment 6004 6004 1 6.0 3.8519 0.09711 .
date 44799146 7466524 6 5011.5 4789.9626 < 2e-16 ***
treatment:date 397599 66267 6 5011.5 42.5117 < 2e-16 ***This was driven by significantly larger oysters in the salinity treated groupfrom May 2025-Oct 2025, but there were no other differences and there is no difference at the most recent time point.
date = 20240624:
contrast estimate SE df z.ratio p.value
control - treated -0.746 4.60 Inf -0.162 0.8711
date = 20240909:
contrast estimate SE df z.ratio p.value
control - treated -7.058 4.59 Inf -1.539 0.1238
date = 20241211:
contrast estimate SE df z.ratio p.value
control - treated -4.944 4.68 Inf -1.057 0.2906
date = 20250520:
contrast estimate SE df z.ratio p.value
control - treated -12.102 4.58 Inf -2.645 0.0082
date = 20250825:
contrast estimate SE df z.ratio p.value
control - treated -46.072 4.86 Inf -9.478 <0.0001
date = 20251008:
contrast estimate SE df z.ratio p.value
control - treated 27.092 4.89 Inf 5.542 <0.0001
date = 20260522:
contrast estimate SE df z.ratio p.value
control - treated -7.947 4.92 Inf -1.615 0.1064