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Signs of the Seasons: A Maine Phenology Program Coastal Field Guide 2013 (PDF)

Phenophase Datasheet: Rockweed (Ascophyllum nodosum) Procedures A & B

Ascophyllum Growth Data Procedures Sheet C & B

The Signs of the Season’s Coastal Field Guide is adapted in part from Nature’s Notebook, USA National Phenology Network.

INTRODUCTION

This coastal species field guide is focused on observing the rockweed species, Ascophyllum nodosum, in the intertidal zone of the Maine and New Hampshire coast. There are three procedures to consider in monitoring Ascophyllum. Choosing all three of the following components, as part of this monitoring effort, will give us the most valuable data. However, according to your time availability, you may at times choose the ones that are of most immediate concern to researchers. You will receive training, equipment and support for all three procedures.

Procedure A: Phenophase

Observations All participants will observe the phenophases of Ascophyllum as part of the Coastal Signs of the Seasons Program. The observations will be recorded on the Rockweed Datasheet and entered into the SOS website page: SOS Coastal Observers page.

Procedure B: Water Quality Measurements

The water quality parameters affecting the growth and phenophases of Ascophyllum are temperature and salinity. The water quality monitoring will be conducted each time the phenophase observations are made in Procedure A: Phenophase Observations.

Procedure C: Age Assessment and Growth Rates

You may assist the research further by Assessing the Age and Growth Rates of the individuals you are observing in Procedure A. This can be accomplished once per year and typically in March/April though it can be done at any time during the season. The water quality measurements should also be taken at this time.

Each of these Procedures is described in the instructions of this guide and training will be provided. Equipment, when available, will also be provided. We greatly appreciate your time, interest and assistance in conducting this research.


ROCKWEED PROTOCOL

Natural History of Rockweed

Ascophyllum nodosum is a member of a brown seaweed group called “rockweeds.” Rockweeds are conspicuous on North Atlantic rocky shores and provide habitat, shelter, and resources for a variety of marine biota. In particular, A. nodosum, sometimes called knotted wrack, is abundant in the mid-intertidal zone on sheltered, hard substrate. A hardy organism, A. nodosum can be found in varying environments and is tolerant of fluctuating temperature and salinity levels. Ascophyllum nodosum on the Northeast Atlantic coastline has a range from NJ to Baffin Island, Canada, and is found in the following states: NJ, NY, CT, RI, MA, NH, ME.

Each individual is either male or female. Reproduction appears to be correlated with temperature (Bacon & Vadas 1991), with the onset of reproduction occurring when water temperatures are 6˚C, and peak reproduction at 10˚C. This species is long-lived (a perennial plant): studies have documented that individuals can live for decades! Like trees and other organisms, A. nodosum can record annual rate of growth and can provide information as to good growth years versus poor growth years. Each spring, individuals lay down a new vesicle (airbladder) at the tip of each frond. Measuring the distance between vesicles provides what the growth rate is from one growing season to the next.

Before you go into the field:

  • You will need to assess the tidal stage and plan accordingly. Tide charts may be found by selecting your region and location at Maine Boats and Harbors website where you can print monthly tide charts: http://maineboats.usharbors.com/maine-tide-charts
  • Make certain you are prepared for the weather conditions, and that it is safe. Check the weather forecast for the time you will be in the field and wear appropriately safe shoes and clothing.
  • Make sure you have the following field supplies and equipment: a transect line (soft tape measure), field hand lens, clipboard with field guide and data sheets, pencil, water quality equipment (thermometer and refractometer).

Bacon, L.C. and R. L. Vadas (1991) A model for gamete release in Ascophyllum nodosum (Phaeophyta). Journal of Phycology 27 (2): 166-­‐173


PROCEDURE A. Ascophyllum nodosum (Rockweed) Phenology Instructions

PLEASE BE CAREFUL! The intertidal zone is a slippery place. Your safety is our #1 concern. Please wear sturdy, closed-­‐toed shoes, dress appropriately for the weather, and walk slowly on slick, uneven terrain. We highly recommend this monitoring be conducted in pairs for safety.

Please plan to evaluate the state of reproduction for Ascophyllum ideally one time per week (especially during the reproductive phases which start in very early spring) by observing the phenophases. If that is not feasible, make your observations twice a month. Pay particular attention to tide levels. In general, you will be able to access the shore one and a half hours before and after low tide. If your area is higher than high tide level, it may be accessible at all tide levels.

  1. For each monitoring month, establish a representative transect (approximately 10 m) that runs parallel to the water line, and passes through a patch of Ascophyllum nodosum in the intertidal zone. The location for your site should be mid-­‐intertidal in the stand of rockweed. Choose a site you can return to for the same area each time. If you are able, take temperature and salinity measurements each time (instructions below in Procedure B).
  2. Haphazardly choose10 individuals along the transect line. When handling individuals, take care. Although they are quite robust, they can be broken from their holdfast and will not reattach. It is difficult on some individuals to distinguish the primary shoot — in this case choose the longest frond close to the middle to check for phenophases. Rarely, there may be different phenophases occurring on one individual — in that case establish the majority phase of the individual. Also, avoid observing damaged fronds.
  3. For each individual, evaluate the state of the receptacles (see photographs) to determine what phase each of the 10 individuals is in. You do not need to count the receptacles. The value for each phenophase would be how many plants are in that phase (you would put in that number (value) after Y or N or ?) out of the 10 plants. Essentially, how many plants out of the ten are in that particular phase at the time of your observation? The receptacles on any given plant will all be in the same phase at the same time (if there are slight differences, use the phase for the majority of individuals). After recording the phenophase on the Rockweed Phenophase Field Datasheet, enter your observations online at the SOS website at http://umaine.edu/signs-of-the-seasons/, in the SOS Coastal Observers page.

Ascophyllum Phenophase Protocol adapted from GLOBE® 2005 Seaweed Reproductive Phenology Protocol, Earth System

ROCKWEED PHENOLOGY PROTOCOL

Did you know?

This species of rockweed is long-lived (a perennial plant): studies have documented that individuals can live for decades! What does this species look like? Ascophyllum nodosum, sometimes called knotted wrack, is a member of a brown seaweed group called “rockweeds.” It forms single bladders in long, strap-like fronds, which hang downwards, draping sheltered intertidal rocks. A number of fronds grow from each holdfast (where the seaweed is attached to the rock).

Why observe this species?

Rockweeds are conspicuous on North Atlantic rocky shores and provide habitat, shelter, and resources for a variety of marine biota. Where is this species found? NE Atlantic coastline has a range from NJ to Baffin Island, Canada. States where it is found: NJ, NY, CT, RI, MA, NH, ME. Distribution Abundant in the mid-intertidal zone on sheltered, hard substrate. A hardy organism, Ascophyllum nodosum can be found in varying environments and is tolerant of fluctuating temperature and salinity levels.

General Phenology and Life History

Each individual is either male or female. Reproduction appears to be correlated with temperature (Bacon & Vadas 1991) — the onset of reproduction generally occurs when water temperatures are 6˚C (43˚F), and peak reproduction at 10˚C (50˚F). Like trees and other organisms, Ascophyllum nodosum provides a record of its annual growth, which can be used to see which years were good or bad for growth. Each spring, individuals lay down a new vesicle (airbladder) at the tip of each frond. Measuring the distance between vesicles provides what the growth rate is from one growing season to the next.

Which phenophases should I observe?

Special instructions: Record observations on a haphazard subset (10 individuals) of the rockweeds at your site, determining how many individuals observed are in each phenophase. Do not make observations on rockweed individuals next to each other but every other one or haphazardly along the10 meter transect line.

Do you see…

New side branches?
One or more new sides branches with smooth tips are visible on the plant. Side branches are considered “new” until they develop a receptacle, or until they reach a similar width and tough texture as the mature shoot on which they are growing. Do not include side branches with ragged tips, where a receptacle has recently detached.

How many individuals out of the ten observed have new side branches present? 1,2,3,…10

Receptacles?
One or more receptacles are visible on the plant. Receptacles are oval pods that are initially flat and become inflated, changing from olive-green to orange or dark brown, sometimes becoming torn.

How many of the ten observed individuals have receptacles present? 1,2,3…10

Flat receptacles?
One or more flat, olive-green receptacles are visible on the plant.

How many of the ten observed individuals are in this phase? 1,2,3,…10

Smooth inflated receptacles?
One or more inflated, smooth, olive-green receptacles are visible on the plant.

How many of the ten observed individuals are in this phase? 1,2,3,…10

Dotted inflated receptacles?
One or more inflated, yellow or orange receptacles studded with small, raised dots are visible on the plant. Do not include receptacles that are torn or ruptured.

How many of the ten observed individuals are in this phase? 1,2,3,…10

Torn receptacles?
One or more torn or ruptured, orange or dark brown receptacles are visible on the plant.

How many of the ten observed individuals are in this phase? 1,2,3,…10

Phenophase Definitions

Directions: As you report on phenophase status (Y, N or ?) on the datasheets, refer to the definitions on this sheet to find out what you should look for, for each phenophase in each species. To report the intensity of the phenophase, choose the best answer to the question below the phenophase, if one is included.

Leaves
New side branches: One or more new sides branches with smooth tips are visible on the plant. Side branches are considered “new” until they develop a receptacle, or until they reach a similar width and tough texture as the mature shoot on which they are growing. Do not include side branches with ragged tips, where a receptacle has recently detached. How many individuals out of the ten observed have new side branches present? 1,2,3,…10 Rockweed (Ascophyllum nodosum) leaves
Flowers
Receptacles: One or more receptacles are visible on the plant. Receptacles are oval pods that are initially flat and become inflated, changing from olive green to orange or dark brown, sometimes becoming torn. How many individuals of out of the ten observed have receptacles present? 1,2,3…10
Flat receptacles: One or more flat, olive-green receptacles are visible on the plant. How many of the ten observed individuals are in this phase? 1,2,3,…10 rockweed flowers: flat receptacles
Smooth inflated receptacles: One or more inflated, smooth, olive-green receptacles are visible on the plant. How many of the ten observed individuals are in this phase? 1,2,3,…10 rockweed flowers: smooth inflated receptacles
Dotted inflated receptacles: One or more inflated, yellow or orange receptacles studded with small, raised dots are visible on the plant. Do not include receptacles that are torn or ruptured. How many of the ten observed individuals are in this phase? 1,2,3,…10 rockweed flowers: dotted inflated receptacles
Torn receptacles: One or more torn or ruptured, orange or dark brown receptacles are visible on the plant. How many of the ten observed individuals are in this phase? 1,2,3,…10 rockweed definitions: torn receptacles

(Photos by GLOBE Project & E Stancioff)


PROCEDURE B. Water Quality Instructions

  1. Pipette and daylight plate; poor and good coverage on the slide; salinity is read on the right-hand side, specific gravity on the leftWade or reach into the water at the closest point to the rockweed transect that you are observing. Do not disturb the bottom. Take the temperature reading, and pipette the salinity sample at the exact same location ideally 5 to 7 inches below the surface of the water; note that often this can only be a few inches due to the tidal stage and safety. Submerge the thermometer probe until a steady reading is displayed. Submerge the pipette, rinse once and fill.
  2. In a stable spot (away from the water), record the water temperature on field data sheet and measure salinity using the hand-held refractometer.
  3. First calibrate the refractometer by opening the lid and placing several drops of distilled water on the daylight plate. Keep the refractometer in a horizontal position. Gently close the lid and be sure sample is evenly distributed with no bubbles across the daylight plate. Using the screwdriver to turn the scale-adjusting knob, adjust the boundary line (between the blue and white regions) to read at the zero line. Use the right-hand scale (o/oo).
  4. Use a Kim wipe to remove the distilled water. Place two drops of sample water from the pipette onto the daylight plate. Gently close the lid of daylight plate. If necessary, point the refractometer towards or away from the sun to brighten or darken the field of view. You can also adjust for your eyesight by twisting the black ring near the eyepiece to focus the field of view. Read the salinity value on the right hand side. The value is where the boundary line of the blue and white fields cross the scale. Record the value on the field data sheet.
  5. Rinse the daylight plate with distilled water and wipe clean with a Kim wipe. If the daylight plate is smeared with oil or similar liquids, it will repel the sample and alter the measurement.
  6. Enter your data for water quality parameters each time on the Water Quality datasheet and enter on the SOS website in the SOS Coastal Observers page.

Water Quality Methods adapted from: Stancioff, Esperanza. Clean Water: A Manual for Coastal Water Quality Monitoring, published by Maine Sea Grant, 1992, revised 1996


PROCEDURE C. Assessing Age and Growth Rate for Ascophyllum Instructions

Note: For both aging and growth rate, choose intact individuals and conduct this procedure once per year at any time during the season; though the preference is to conduct this in March/April.

  1. To obtain minimum age of the plant, count all the vesicles (air bladders) on an intact primary shoot (if difficult to find primary shoot, select a shoot towards the middle of individual). Ascophyllum nodosum is dichotomous in branching, meaning the frond splits in a “Y” — follow one shoot all the way up. For example, in the line drawing of A. nodosum, the individual is at least 4 years old. Counting on the primary shoot, from the holdfast upwards, there are 4 vesicles (noted with yellow circles). Count and record the number of vesicles present, from the bottom to the top (oldest growth to the newest growth).
  2. To measure growth rate, measure the distance between each internode section (from mid-vesicle to mid-vesicle — What internode, “I”, is in the line drawing below). This measurement is the growth in one year. Measurements of all the intermodal sections for an individual will allow one to see differences in growth rates between years and compare to other individuals. Measure growth rate from the newest internode to the oldest internode — so from the top down.
  3. Enter your data for water quality parameters and growth rate on the Ascophyllum Growth datasheet, and enter online in the SOS website at the SOS Coastal Observers page.

Ascophyllum Growth and Aging Protocol developed by Jessica Muhlin, Maine Maritime Academy.

illustration showing rockweed vesicles and measurement for 1 year  of growth

Figure: A, apical tip; B, basal shoot; H, holdfast; I, internode; L/lateral shoot; P, primary shoot; R, receptacle; S, stump; V, vesicle.

Figure © FAO, http://www.fao.org/docrep/x5819e/x5819e02.gif

Terminology for Ascophyllum nodosum/algal morphology

Stump: When the body of the plant (called the thallus) is cut so that the branch of the alga is initially missing the region where growth occurs (the apical meristem).

Internode: The region of growth that is between two air bladders (vesicles).

Apical tip: The tips of the plant where growth occurs (they grow from the tips of the thallus).

Plant: an assemblage of fronds (branches) arising from a common holdfast.

Stand: a group of plants within a defined area.

Vesicles: Airbladders on that thallus. These are dilations of the shoot produced at intervals related to rate of annual shoot elongation.

Receptacles: Reproductive organ of the plant. Receptacles are produced along lateral (side) shoots

Shoot: A part of the thallus resulting from growth. Shoots are analogous to branches of a tree.

Primary shoot: The main branch (trunk) of the individual, originating from the holdfast

Lateral shoot: A side branch that comes off a primary shoot.

Intact shoot: A branch that has is able to grow from the tips of the branches out.


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