@misc{9227941,
  abstract     = {{Kelp forests are among the most productive ecosystems on Earth, releasing detritus year-round through direct blade erosion, storm-induced detachment, wave breakage, seasonal shedding, as well as indirect urchin grazing. Fragmental kelp detritus is transported from the euphotic zone to deeper parts of the ocean such as fjords, where decomposition rates are very low and detritus may contribute to long-term carbon storage. However, as detritus moves along the seafloor, detrital fragments may become more palatable to small benthic consumers. Fragmentation, such as shredding through sea urchin grazing, increases availability. Different irradiance levels could for example influence photosynthetically active fragment cells. Aging could increase palatability through microbial colonization. Increased palatability and linked consumption reduce kelp fragment carbon sequestration potential through recirculation of carbon.

This study examined how fragmentation origin (mechanical versus urchin gut passage), aging, and irradiance influences chemical composition (C:N ratios) and through a series of feeding trials how this is linked to fragment palatability for mesograzers. Using C:N ratio as a proxy for nutritious value and palatability, a combination of no-choice and multiple-choice feeding trials were performed to assess separate and combined effects of experimental factors on mesograzer consumption rates and preferences. 

Fragmentation method and aging duration were significant predictors of C:N ratio, with mechanically fragmented material developing strongly elevated C:N ratios at long aging duration, while urchin-grazed material maintained lower C:N ratios. The higher irradiance treatment accelerated carbon fixation in mechanically fragmented material. Chemical differences between treatments translated into detectable feeding preferences only partially. In multiple-choice feeding trials, Gammarus sp. showed a significant preference for urchin-grazed, long-aged material while in Littorina littorea aging significantly predicted consumption. Comparison between fresh and reconstituted material indicated that both morphological and chemical properties of detritus contribute to palatability.

The findings contribute to a better understanding of Blue Carbon dynamics and the role of kelp-derived detritus in marine carbon sequestration and help improve estimates of the ocean’s Blue Carbon capacity.}},
  author       = {{Tichawa, Sarah}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{What makes kelp more palatable for mesograzers? Effects of urchin grazing, light and aging on kelp detritus palatability, and its role in carbon sequestration}},
  year         = {{2026}},
}