Dataset: Zostera marina flowering shoots

Name: Heights and stages of Zostera marina flowering shoots determined from from weekly-biweekly surveys in shallow and deep zones at two sites in Massachusetts, USA in 2019
Published: 2021-03-29
Keywords: oceans

Cite This Dataset

DOI:10.26008/1912/bco-dmo.846985.1

Spatial Extent: N:42.55921 E:-70.80578 S:42.42009 W:-70.91553

Temporal Extent: 2019-06-04 - 2019-08-27

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:

2021-03-29

Restricted:

Validated:

Yes

Current State:

Final no updates expected

Heights and stages of Zostera marina flowering shoots determined from from weekly-biweekly surveys in shallow and deep zones at two sites in Massachusetts, USA in 2019

Abstract:

This dataset includes heights and stages of Zostera marina from weekly-biweekly surveys in the shallow and deep zones at two sites in Massachusetts, USA in 2019. Eleven surveys of two different eelgrass beds were conducted every 1-2 weeks starting June 4th and ending August 27th during the summer of 2019. The two sites were West Beach in Beverly (N 42.55921, W 70.80578) and Curlew Beach in Nahant (N 42.42009, W 70.91553).

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Archival Copy

Version Date	Archive	Persistent Identifier (PID)	Date PID Issued
2021-03-29	Marine Biological Laboratory/Woods Hole Oceanographic Institution Library (MBLWHOI DLA)	10.26008/1912/bco-dmo.846985.1	2021-04-01

Methods & Sampling

We conducted eleven surveys of two different eelgrass beds in Massachusetts every 1-2 weeks starting June 4th and ending August 27th during the summer of 2019. The two sites were West Beach in Beverly (N 42.55921, W 70.80578) and Curlew Beach in Nahant (N 42.42009, W 70.91553). Each survey consisted of a 20 m transect being laid out parallel to shore 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.

During each survey, we measured the height of up to 3 flowering shoots per quadrat. In addition to measuring the height, we measured the height of the oldest and youngest spathes, the inflorescence height, and the flowering stage of the oldest and youngest spathes for each shoot. We defined flowering stages following De Cock (1980): 1 (styles erect out of spadix); 2 (styles bend back into spadix after pollination); 3 (half-anthers release pollen); 4 (half-anthers have been released, seeds maturing); 5 (seeds have started to release); and 6 (post-seed release when the flowering shoot begins to wither; Fig. 2 of von Staats et al., 2020). We also included two additional stages that occur before the flowering of the pistils based on our observations in the field: pre-spathe (PS; when a spathe is present, but pistils and anthers have not yet formed) and 0 (pistils and anthers have formed, but styles have not yet erected).

Data Processing Description

Data Processing:
We examined flowering shoot height and spathe number per flowering shoot using separate linear mixed effects models with site, depth, and time (week) as fixed factors and unique quadrat as a random effect to account for non-independence of measurements within the same quadrat. All models included all possible interactions.

To look at the timing of flowering across sites and depths, we compared the developmental stages of the youngest and oldest spathes separately. For our analyses, we combined stages 1-3 into a single stage since relatively few of these stages were found over the course of our study and because flowers only remain in these stages for a few hours to one week at most. Furthermore, the sequence of these stages is not always linear, as stage 3 can begin at the same time as stage 1 or before stage 2 if the flower has not yet been pollinated (De Cock 1980). We used linear regression to assess whether flowering phenology differed among locations (site), with time (measured in days since June 1st, a few days before we began our surveys) as our response variable, site, depth, and developmental stage (treated as a categorical factor) as our predictors, and including all possible interactions.

We also compared the timing of development between the oldest and youngest spathes across sites and depths. For this analysis we looked at the time it took spathes to reach stage 4, the stage in which seeds begin to develop. If stage 4 is reached it means (for the most part) that a given spathe can contribute to the proliferation of the Z. marina population. We used a linear regression with days since June 1 as our response variable, site, depth, and spathe identity (youngest or oldest) as our predictors, and including all possible interactions.

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
flowering_shoots.csv (Comma Separated Values (.csv), 29.06 KB) MD5:9b70865551127d71b7c8ac19d208c256 Primary data file for dataset ID 846985

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
Days_Since_June_1	The number of days since June 1st that data was collected (June 1st was a few days before our first survey)	unitless	time_elapsed
Week	The assigned collection week number. Numbers start at 1 for the first week of collection and go up 1 each collection week.	unitless	time_point
Site	The site of collection. Either West (West Beach, Beverly, MA) or Dorothy (Curlew Beach, Nahant, MA).	unitless	site
Depth	SH (shallow zone) or DP (deep zone)	unitless	site_descrip
Quadrat	For each transect, quadrats will be in order with 1 being the first quadrat of each transect at 2m and 10 being the last at 20m. Some weeks go higher than 10 quadrats if we sampled more or had empty quadrats. Week 4 quadrat numbers do not correspond to transect position/sampling order.	unitless	site
Max_Height	The height of the flowering shoot measured to the nearest half centimeter.	centimeters (cm)	height
Inflorescence_Height	The height of the inflorescence of the flowering shoot (the height from the first branch to the top of the shoot); measured to the nearest half centimeter.	centimeters (cm)	height
number_of_spathes	The total number of spathes found on a given shoot.	number of spathes	sample_descrip
youngest_stage	The flowering stage that the youngest spathe on a given flowering shoot is in at time of collection. The youngest spathe is considered the topmost spathe on a shoot. Stages were defined following De Cock (1980); see metadata for description.	unitless	stage
oldest_stage	The flowering stage that the oldest spathe on a given flowering shoot is in at time of collection. The oldest spathe is considered the bottommost spathe on a shoot. If there is only one spathe on a flowering shoot, then it is filled in as the oldest spathe and the youngest is left blank. Stages were defined following De Cock (1980); see metadata for description.	unitless	stage
youngest_height	The height from the base of the shoot to the branch of the youngest spathe on a shoot; measured to the nearest half centimeter.	centimeters (cm)	height
oldest_height	The height from the base of the shoot to the branch of the oldest spathe on a shoot; measured to the nearest half centimeter.	centimeters (cm)	height
Unique_Quadrat	A unique number assigned to each quadrat.	unitless	sample_descrip

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Dataset: Zostera marina flowering shoots