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Minako AZUMA (MSc student)
Research interests:
Dynamics of tidepool plant/animal assemblages on a temperate rocky shore
- Algal diversity in tide pools under the influences of physical and biological factors
- Effects of algal diversity on seaweed-associated invertebrate assemblages
In the intertidal of western Kyushu, various species of seaweed occur in rock pools.
Seaweed assemblages vary with environmental gradients, including the changes in water temperature and salinity depending on the positioning and physical characteristics of pools.
Furthermore, interactions among seaweed may affect species composition, e.g. competition for light and space, attenuation of heat stress by canopy.
Thus, seaweed's diversity may be affected by abiotic and biotic factors.
Seaweed has important roles not only as a primary producer but also as a provider of habitats for small invertebrates.
Invertebrates can use seaweed as
a. refugia from potential predators
b. place to engage in reproductive activities
c. place to conduct feeding activities; eating plants directly or suspension feeding on the plants
As physical characteristics such as size and morphology vary among seaweed species, invertebrates can select their host plants based on their requirements.
Thus, different assemblages of invertebrates may be found on the surfaces of different seaweed and we can suggest that seaweed's diversity may affect associated animals' diversity.
As a first step of my study, I have surveyed the distribution pattern of seaweed-associated invertebrates by focusing on the five dominant algal species in the intertidal tidepools of western Kyushu.
Gammarids, caprellids, isopods, bivalves, snails, polychaeta and larvae of midges were found.
The survey revealed that seven dominant species of amphipods occurred with seaweed-dependent distribution patterns; distribution changed with the tidal height of pools.
Amphitoe valida, a tube building gammarid, showed differences in body size on different algal species.
They construct a nest using detritus, plant materials and glandular secretions and appear to be rather sedentary, spending much of their time within their tubes.
Thus, their choice of host plant is considered to be related to the ease of making a nest.
Corallina pilulifera, the dominant red alga in tidepools, may be morphologically most convenient for Amphitoe valida as large-bodied individuals of A. valida occurred only on C.pilulifera.
On C.pilulifera, A.valida may be able to engage in both feeding and reproduction activities.
Caprellids occurred on all five algae and had tidal height-dependent distribution patterns.
Some other invertebrate taxa showed algae-dependent distribution patterns.
Presentations :
- Ecology of seaweed-associated fauna in tidepools. The 16th annual meeting of the Japanese Association of Benthology.
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