| dc.description.abstract | Sediment granulometry, microphytobenthos and meiobenthos were investigated
at five habitats (white and grey sands, backreef border, shallow and deep
thalassinid ghost shrimp mounds) within the western lagoon at Discovery Bay,
Jamaica. Habitats were ordinated into discrete stations based on sediment
granulometry. Microphytobenthic chlorophyll-a ranged between 9.5- and 151.7
mg m-2 and was consistently highest at the grey sand habitat over three sampling
occasions, but did not differ between the remaining habitats. It is suggested that
the high microphytobenthic biomass in grey sands was related to upwelling of
nutrient rich water from the nearby main bay, and the release and excretion of
nutrients from sediments and burrowing heart urchins, respectively. Meiofauna
abundance ranged from 284- to 5344 individuals 10 cm-2 and showed spatial
differences depending on taxon. Of 22 higher taxa recorded, nematodes
dominated followed by copepods, together accounting for ~80 % of all
individuals. Both taxa were most abundant in grey sands, suggesting a response,
either directly or indirectly, to the high microphyte biomass. Significant withinhabitat
spatial variability in both meio- and microphytobenthos was found,
causes of which are discussed. Nematode feeding groups varied between
habitats. Fine white sands and both thalassinid mound habitats were dominated
by non-selective deposit feeders. Slender and plump nematode morphotypes
were found, yet the plump morphotype was largely absent from coarse sands
subjected to high wave swash at the backreef border habitat. Here, nematode
lengths were significantly higher than at other habitats. Nematode biomass
spectra differed significantly between habitats, with a shift in peak biomass
values towards larger size classes in the disturbed sediments. It is suggested that
3
longer and larger nematodes represent an adaptation to sediment disturbance,
helping to prevent being displaced from the benthos by hydrodynamic forces and
bioturbation. | en_US |
