Dataset: Permanent plot vegetative density

Name: Vegetative density data from two surveys of eelgrass flowering in shallow and deep zones at four different sites in Massachusetts, USA in 2019
Published: 2021-03-30
Keywords: oceans

Cite This Dataset

DOI:10.26008/1912/bco-dmo.847062.1

Spatial Extent: N:42.59711 E:-70.65592 S:42.42009 W:-70.9155

Temporal Extent: 2019-06-26 - 2019-08-16

Project:

RUI: Collaborative Research: Trait differentiation and local adaptation to depth within meadows of the foundation seagrass Zostera marina (ZosMarLA)

Principal Investigator:

A. Randall Hughes (Northeastern University)

BCO-DMO Data Manager:

Shannon Rauch (Woods Hole Oceanographic Institution, WHOI BCO-DMO)

Version:

Version Date:

2021-03-30

Restricted:

Validated:

Yes

Current State:

Final no updates expected

Vegetative density data from two surveys of eelgrass flowering in shallow and deep zones at four different sites in Massachusetts, USA in 2019

Abstract:

This dataset includes vegetative densities from two surveys of eelgrass flowering in shallow and deep zones at four different sites in Massachusetts, USA in 2019. The four sites were West Beach in Beverly (N 42.55921, W 70.80578), Curlew Beach in Nahant (N 42.42009, W 70.91553), Lynch Park in Beverly (N 42.54488, W 70.85842), and Niles Beach in Gloucester (N 42.59711, W 70.65592).

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Archival Copy

Version Date	Archive	Persistent Identifier (PID)	Date PID Issued
2021-03-30	Marine Biological Laboratory/Woods Hole Oceanographic Institution Library (MBLWHOI DLA)	10.26008/1912/bco-dmo.847062.1	2021-04-01

Methods & Sampling

We conducted two surveys of four different eelgrass beds in Massachusetts during the summer of 2019. The four sites were West Beach in Beverly (N 42.55921, W 70.80578), Curlew Beach in Nahant (N 42.42009, W 70.91553), Lynch Park in Beverly (N 42.54488, W 70.85842), and Niles Beach in Gloucester (N 42.59711, W 70.65592). Surveys were done in both the shallow and deep zone. These zones were defined as being along the respective edges of the eelgrass beds. The exact depths of the zones varied from bed to bed. The first survey of each site was conducted at the end of June/early July. In these surveys, we counted the number of both vegetative and flowering shoots in 5-7 0.0625 m^2 quadrats from each of three previously established permanent quadrats per depth per site. This gave us a total of 15-21 0.0625 m^2 quadrats per depth per site. The second survey of each site was conducted in mid-August. Instead of doing the surveys from within the permanent quadrats, we did so outside of them to avoid overlap. We counted the number of vegetative and flowering shoots within 0.0625 m^2 quadrats every 2 m along a 30 m transect (that would be extended for each quadrat that had no eelgrass). This led to there being 15-18 quadrats per depth per site.

Data Processing Description

Data Processing:
We analyzed the number of vegetative shoots per 0.0625 m^2 quadrat using a generalized linear model (GLM) with a negative binomial regression and site, depth, and time (week) as fixed effects and including all possible interactions. We did the same for the density of flowering shoots and the density of all shoots (total density). We analyzed the proportion of flowering shoots (% flowering by density) using a GLM with a quasi binomial distribution and logit link function with site, depth, and time (week) as our fixed effects and including all possible interactions. For all of these analyses week was treated as a categorical factor.

Statistical analyses were conducted using R Statistical Software v. 3.6.0 (R Core Team 2019). Negative binomial regressions were done using the glm.nb function in the MASS package (Venables and Ripley 2002). We used a significance level of α = 0.05 for all of our analyses.

BCO-DMO Processing:
- changed date format to YYYY-MM-DD;
- renamed fields to conform with BCO-DMO naming conventions;
- replaced "NA" with "nd" to indicate "no data".

Data Files

File
permanent_plot_density.csv (Comma Separated Values (.csv), 10.02 KB) MD5:2060ef8d775aa7737924edd66fff5ddc Primary data file for dataset ID 847062

More Information about this dataset

Funding Sources

Funding Source	Award Number
NSF Division of Ocean Sciences	OCE-1851043

Deployments

None available yet

Instruments

None available yet

Parameters

Date and time formats are described in python strftime() syntax.

Supplied Name	Supplied description	Supplied Units	Standard Name
Date	The date of sample collection; format: YYYY-MM-DD Format: %Y-%m-%d	unitless	date
Month	The month of the survey (June or August) *one of the first surveys was conducted on July 1, but is counted as June.	unitless	month
Site	The site of collection. WB (West Beach, Beverly, MA), DC (Curlew Beach, Nahant, MA), NB (Niles Beach, Gloucester, MA), or LP (Lynch Park, Beverly, MA)	unitless	site
Depth	SH (shallow zone) or DP (deep zone)	unitless	site_descrip
Permanent_Quadrat	For the first surveys (June/July) the permanent quadrat that data came from (there are 3 permanent quadrats per depth per site)	unitless	site
Transect_Meter_Mark	For the second surveys (August), the corresponding transect meter mark that samples were taken from	unitless	site
Cattle_Tag	For the first round of sampling, the corresponding cattle tag number for each sample	unitless	sample
Vegetative_Density	The number of vegetative shoots in each quadrat	number of shoots per quadrat	density
Flowering_Density	The number of flowering shoots in each quadrat	number of shoots per quadrat	density
Total_Density	The number of vegetative AND flowering shoots found in each quadrat	number of shoots per quadrat	density

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Dataset: Permanent plot vegetative density