Abstract
Sponges are one of the earliest-evolved and simplest groups of animals,
but they share basic characteristics with more advanced and
later-evolved filter-feeding invertebrates, such as mussels. Sponges are
abundant in many coastal regions where they filter large amounts of
water for food particles and thus play an important ecological role.
Therefore, a better understanding of the bioenergetics and growth of
sponges compared to other filter-feeders is important. While the
filtration (pumping) rates of many sponge species have been measured as a
function of their size, little is known about their rate of growth.
Here, we use a bioenergetic growth model for demosponges, based on the
energy budget and observations of filtration (F) and respiration rates (R). Because F versus dry weight (W) can be expressed as F = a1Wb1 and the maintenance respiratory rate can be expressed as Rm = a2Wb2, we show that if b1~ b2 the growth rate can be expressed as: G = aWb1, and, consequently, the weight-specific growth rate is µ = G/W = aWb1−1 = aWb where the constant a
depends on ambient sponge-available food particles (free-living
bacteria and phytoplankton with diameter < ostia diameter). Because
the exponent b1 is close to 1, then b ~ 0, which implies µ = a
and thus exponential growth as confirmed in field growth studies.
Exponential growth in sponges and in at least some bryozoans is probably
unique among filter-feeding invertebrates. Finally, we show that the F/R-ratio
and the derived oxygen extraction efficiency in these sponges are
similar to other filter-feeding invertebrates, thus reflecting a
comparable adaptation to feeding on a thin suspension of bacteria and
phytoplankton.
Original language | English |
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Article number | 607 |
Journal | Journal of Marine Science and Engineering |
Volume | 10 |
Issue number | 5 |
Number of pages | 13 |
ISSN | 2077-1312 |
DOIs | |
Publication status | Published - 2022 |
Keywords
- Bioenergetic growth model
- Energy budget
- Filtration rate
- Respiration
- F/R-ratio
- Filter-feeding