Barnacles are one of the dominant macrofouling organisms found in the intertidal region throughout the world. Among the different species of barnacles Balanus amphitrite (=Amphibalanus amphitrite) is a favoured candidate organism used in experimental studies. Larval development in this barnacle includes planktotrophic naupliar stages followed by pre-settling cyprid instar. Studies have shown that availability of food during naupliar development is of critical importance to successful metamorphosis of the cypris larva. Traditionally barnacle larvae are raised in the laboratory providing mono-algal cultures of diatoms as food organisms. Such a luxury is not a reality in the wild. Observations to quantify the food available for the nauplii deliberated by monitoring the faecal pellets egested by freshly captured larvae from a tropical estuarine environment (Dona Paula bay, Goa, west coast of India) influenced by monsoon and characteristic temporal variations in the phytoplankton abundance and diversity indicated that the percentage of defaecating larvae (an indicator of food consumed) was comparatively higher during the pre-monsoon season. Generally this season is characterized by lower chlorophyll-a concentration. However, the average number of faecal pellets defaecated by a larva remained constant irrespective of the season. Earlier work in the study area depicts temporal changes in phytoplankton community structure; diatoms dominate during the post-monsoon season whereas dinoflagellates dominate during the pre-monsoon season. These observations indicate a possible shift in the food available for the larvae. As the faecal pellets did not always have remnants of diatom frustules, it is possible to say that the larvae survived on food material other than diatoms. Settlement of barnacles on panels of aluminium in the vicinity was monitored throughout the year and peaked during the pre-monsoon season. It is thus possible to infer successful larval development and metamorphosis in this barnacle species on varying forms of food.

Downward fluxes of particulate matter were investigated in the polynya of Terra Nova Bay (western Ross Sea) from February 1995 to December 1997. The main biological components were siliceous phytoplankton (diatoms, silicoflagellates and parmales), abundant faecal pellets of several types and zooplankton (mainly shelled pteropods). Vertical fluxes of particles occurred mainly through diatoms and faecal pellets in the first and second part of the summer, respectively. The highest fluxes were recurrently observed in late summer, when faeces contributed up to 100% of organic carbon. Unusually high fluxes were recorded in winter 1995, when faecal pellets accounted for 84.6% of the organic carbon. Peak fluxes were always driven by the sinking of faecal pellets, that hence appear to be the most efficient vector of export in the polynya of Terra Nova Bay. A major flux component was the pteropod Limacina helicina, which repeatedly sank in high amounts after the growing season. In April–June, L. helicina probably transported biogenic carbon to deep layers as a passive sinker. The inclusion of pteropods in flux estimates resulted in values that were up to 20 (for total mass), 25 (for organic matter) and 48 (for carbonate) times higher than the previously measured fluxes. Fluxes are known to be biased by swimmers, but ultimately attention must be paid to a possible erroneous categorization of some zooplankton as swimmers to avoid severe underestimation of fluxes of total mass (up to 95% in our study), organic matter (up to 96%) and carbonate (up to 100%).