Herbarium
sheet of each seagrass species (with flowering parts)
· Collect each quarter and well document for the International
Seagrass Herbarium at the Museum of Natural History, Smithsonian,
Washington, DC
Mail to: Dr. Fred Short,
SeagrassNet
Jackson Estuarine Laboratory, UNH,
85 Adams Point Road,
Durham, NH 03824 USA
· Obtain and complete herbarium label from www.SeagrassNet.org
and attach to each herbarium sheet
Photographic record (1 photo of each 1/4 m2 quadrat taken from
above and including the sampling quadrat identification number label)
· Send used cameras to the global seagrass photo
archive
Mail to: Mr. Len McKenzie
Northern Fisheries Center
PO Box 5396
Cairns, QLD 4870
Australia
Seagrass cover, a visual estimate of 1/4 m2 quadrat (50 x 50 cm)
· Estimate percent cover for all species combined
on a scale (0-100%) in each of the quadrats (use % cover in order
to preserve as much information in the raw data as possible, rather
than using a Braun-Blanquet scale)
· Estimate percent cover for each species on a scale
(0-100%) in each of the quadrats
Canopy Height:
· Measure canopy height of the dominant species in quadrat
ignoring the tallest 20% of leaves and identify any grazing evidence.
Express results as canopy height for the species.
Biomass
· Collect a 0.0035 m2 core (7 cm diameter) to establish
a cover vs. biomass regression. For all of the quadrats with cover
estimates (above), take a biomass core outside the quadrat within
1m of the quadrat, in an area of the same seagrass species and cover
as the quadrat (to your best judgment). When placing the core tube,
take care to insure that all shoots originating in the core area are
inside the tube.
The biomass sample is divided into Leaves (all aboveground green plant
parts), Rhizome plus roots (all live plant parts of the horizontal
rhizome and roots that are attached), and Stems (all plant material
extending vertically above the horizontal rhizome with attached roots).
Epiphytes are scraped from the leaves. Leaves are rinsed in fresh
water, dried to constant wt (60° C for 24hr) and weighed. Process
biomass samples (g dry wt m-2), enter on waterproof
data forms, and submit data to SeagrassNet. Send a hard copy
of all data sheets to UNH.
Sexual reproduction
· Count the number of flowers, fruits or seeds or flowering
stems in a core for all seagrass species. Express results as Flower/Fruit/Seed
per area.
Shoot density by species
· From the biomass cores, count all shoots of all species
in the 0.0035 m2 core (7 cm diameter). Express results as total shoots
m-2 and by species
Maximum depth of distribution
· Maximum depth is defined as the depth at which the
deepest shoot is found within a 50 m band of the transect perpendicular
to shore. (For locations with very deep Halophila spp. the deep edge
for this monitoring can be defined as the deepest growing strap-bladed
seagrass.)
· Measure the distance from the left (0m), center (25m),
and right (50m) positions on the deep cross-transect (station C)
· Measure depth, record a GPS location, and simultaneously
record the local time.
· Indicate if the site is intertidal or a tide pool.
Minimum depth of distribution
· Minimum depth is defined as the depth at which the
shallowest shoot is found in the 50 m band, independent of the density
of the bed (may be intertidal).
· Measure the distance from the left (0m), center (25m),
and right (50m) positions on the shallow cross-transect (station A)
· Measure depth, record a GPS location, and simultaneously
record the local time.
· Indicate if the site is intertidal or a tide pool.
Tidal information
· Record what type of tides (diurnal, semi-diurnal)
are found in the area and the tidal range (spring high to spring low)
for the site.
· Record whether the minimum depth of distribution is
in the intertidal (between the spring high and spring low tidal levels)
or subtidal zone (below the spring low tide level).
Environmental data
· Water temperature (continuously measure
temperature, °C) -- Tidbit data loggers at the shallow (A) and
deep (C) stations. The sensors are attached to the permanent marker
and left in the field for 3 months
· Light level (% surface light at deep and shallow
depths) -- Hobo light sensor. Put light meters out at the shallow
and deep stations for 2 weeks at the time of each quarterly sampling,
plus one land-based meter at a nearby spot without shade
· Salinity (measure at every visit and determine
the range over the study area, ppt). Collect water samples at the
3 stations (A, B, & C) and read salinity on the refractometer
back at the laboratory.
· Surface sediment characteristics: estimate
sediment type at three points on each cross transect (Left, Center,
& Right on each cross-transect) and collect a syringe core of
sediment at each station on the primary transect (A, B, & C).
· Surface sediments are collected to obtain:
grain size (% gravel/sand/silt+clay) organic content (% loss on ignition),
and carbonate content (% loss after acidification)
Eelgrass
in New Hampshire
