Seasonal variation of autochthonous and allochthonous carbon sources for fish larvae associated with giant kelp forests

BRUNO, DANIEL O.; RICCIALDELLI, LUCIANA; RIMBAU, SONIA; ACHA, EDUARDO M.; FERNÁNDEZ, DANIEL A.

Connecticut

Conferencia; 44th Annual Larval Fish Conference; 2021

University of Connecticut

This work aimed to evaluate the relative importance of autochthonous (phytoplankton, Macrocystis pyrifera detritus) and allochthonous (terrestrial detritus) sources to the planktonic trophic web supporting fish larvae in the Beagle Channel (Argentina). Monthly samplings were conducted at three sites along the Beagle Channel from March 2015 to February 2016. Larval fish were present throughout the year, of which the notothenioids Patagonotothen spp. were dominant. Stable isotope mixing models revealed that fish larvae feed mainly on zooplankton. The contribution of autochthonous and allochthonous carbon sources varied seasonally. Phytoplankton and terrestrial plants contributed to the particulate organic matter (POM) on surface waters. Parts of the giant kelp M. pyrifera (blade, stipe and holdfast) equally contributed to the particulate organic matter in sediment (SPOM). Zooplankton organisms (the main food item for fish larvae) depended on the POM and phytoplankton in summer, autumn and winter, but on the SPOM in Spring.