Natural diet and grazing rate of the temperate sponge Dysidea avara (Demospongiae, Dendroceratida) throughout an annual cycle

Abstract

ABSTRACT-Sponges are one of the major invertebrate groups inhabiting hard-bottom communities worldwide. In this study, we measured in situ rates of grazing on DOC (dissolved organic carbon), POC (particulate organic carbon), and pico-, nano-and microplankton for the common temperate sponge Dysidea avara throughout a yearly cycle. The natural diet of the species was h~ghly heterogeneous and included procaryotes (heterotrophc bacteria, Prochlorococcus sp., Synechococcus sp.) and eucaryotes (protozoa, phytoplankton, and ciliates) ranging in size from 0.5 * 0.3 (heterotrophic bacteria) to 70 k 0.3 pm (pennate diatoms). Procaryotic cell clearance rates were higher than those for the other groups, suggesting a higher grazing efficiency upon these prey types. Specific clearance rates showed a pattern of decrease with sponge size increase, although they did not vary with prey concentration or with temperature. Overall, procaryotes contributed 74 k 14 % of the total ingested carbon, pico-and nanoeucaryotes contributed 11 i 3"&, and phytoplankton contnbuted 11 i IOU:>. Therefore, Dysidea avara obtained 85% of its ingested carbon from the fract~on smaller than 5 pm and 15% from the fractlon larger than 5 pm. Howcver, the partial contributions of the different groups varied seasonally, following the planktonic composition of the water column Dur~ng winter, phytoplankton was an important component of the total uptake [26°<)), whereas durlng the rest of the year it contnbuted less than 7 % of the total uptake. The capacity of this sponge to feed on a broad size range of prey allowed it to maintain rather constant food uptake throughout the year. These results show the importance of particle type (size) for selective uptake in sponges, as well as the relevance of phytoplankton in the sponge diet. This trophic plasticity may represent an advantage for the species because it attenuates the effects of seasonal fluctuations in the planktonic community. This plasticity in trophic ecology may be one of the main factors contributing to the worldwide abundance and distribution of sponges despite large spatial and temporal variations in food sources.

In situ feeding and element removal in the symbiont‐bearing sponge Theonella swinhoei: Bulk DOC is the major source for carbon

“…swinhoei excretes organic carbon, as do all heterotrophs, in dissolved, particulate, or both forms (Reiswig 1971;Ribes et al 1999). The InEx technique allowed measurement of the net flux of each element.…”

“…Reiswig's (1985) attempt to quantify DOC feeding in situ with boreal glass-sponges was limited by a small data set and a variance too high to draw clear conclusions. More recently, Ribes et al (1998Ribes et al ( , 1999 used recirculating bell jars to measure in situ the diet of a Mediterranean sponge and ascidian. Bulk DOC removal was not observed in either case.…”

Cultivation of Sponge Larvae: Settlement, Survival, and Growth of Juveniles

“…C. crambe has a conservative life strategy with slow growth, lower clearance rates (Turon et al, 1997), and lower volume of choanocyte chambers (Uriz et al, 1995; than D. avara, which makes the former species less able to capture food under adverse conditions (i.e., lack of flow). Conversely, D. avara has an opportunistic life strategy with higher growth and clearance rates than C. crambe and also has a strong filtering activity (Ribes et al, 1999); thus it is able to capture food from the water even under noflow conditions (lower particles availability). These differential capabilities may explain why C. crambe grew more under flow conditions that can enhance the low sponge capacity for pumping water and facilitate the availability of food to the sponge.…”

Spatial Variability of Sponge Assemblages on the Wellington South Coast,New Zealand

“…These low levels of seston are thought to limit the number of other suspension feeders such as mussels, which are very rare on the WSC [99][100][101]. Sponges can phagocytise the smallest fractions of the nano-and picoplankton (particles <2 µm) including bacteria and possibly viruses [64,102,103]. Therefore even though the waters on the WSC may have low levels of organic material, particularly its seston content, the sponges may be able to exploit the low levels of nutritional content in the form of viruses and bacteria and proliferate where other suspension feeders cannot survive.…”

“…Sponge assemblages are influenced by a number of physical factors including: depth [43][44][45]; water flow [44,46]; temperature [26,47]; light intensity [48]; sedimentation [49][50][51][52] and salinity [26,53,54]. Biological factors influencing sponge assemblages include: predation [55][56][57][58]; mutualistic and symbiotic associations [59][60][61]; concentration and plankton diversity [62][63][64]; spatial competition [65][66][67]; and disease [68][69][70][71]. There has been some discussion regarding the relative roles of biological and physical factors in controlling sponge assemblages in different geographic regions.…”