Brenchley, J., & Probert, R.
1997 Aspects of the biology of Zostera in
Not directly relevant - primarily concerns investigations
into the seed biology of Zostera populations in
their natural habitat. Comment that in the Fleet,
previous reports have listed two species of Zostera:
Z. noltii and Z. angustifolia. Molecular
investigation as part of this study indicated that
Z. angustifolia is an environmentally induced
phenotypic morph of Z. marina, and therefore
the Fleet population should be referred to as consisting
of Zostera marina only. It was noted that
the Z. angustifolia morph plants tended to
occur on shallow banks (higher light regime, higher
temperatures), whilst those more typical of Zostera
marina were found in deeper channels. The work
concentrated around Langton Hive Point.
Water temperature at the sediment/water interface
was measured continuously from April >96
to July >97
(data logger). <5EC
in winter to >20EC
in summer, fluctuating diurnally, but less than
Salinity of subsurface water was measured at roughly
monthly intervals. Higher in summer (~35ppt) than
winter (~25 ppt).
Decreasing biomass in winter months - min. in March
with near bare sediment surface. Seeds require cold
stratification to germinate (8 weeks at #6EC),
and will then germinate when temperatures are between
6 and 11EC - not higher.
Salinity levels (equivalent to those observed) had
no significant effect on germination in the laboratory.
Seed germination was considerably faster with higher
% germination achieved under anaerobic conditions
than aerobic, in the laboratory. Field measurements
confirmed that surface sediment was totally depleted
in oxygen. Zostera marina seeds were found
to be intolerant to drying, with best storage conditions
found to be in the hydrated state in anaerobic conditions
at a salinity of 30ppt at 2EC.