Tracing the origins of Calanus sp. in the Saguenay‑St. Lawrence Marine Park (Québec, Canada) using δ13C as a marker

Abstract

The Saguenay-St. Lawrence Marine Park (SSLMP) is a region that sustains a high abundance of zooplankton. The connectivity between zooplankton populations within the SSLMP and the surrounding areas was investigated for Calanus finmarchicus and C. hyperboreus. Deepdwelling stage V copepodites (CVs) were collected in the Marine Park as well as in putative source regions in the St. Lawrence system in July 2009 (a time when they were entering into diapause). In May 2010, at the end of the overwintering period, diapausing CVs were sampled again in the Marine Park. To discriminate the origins and to predict the probable regions of origin of these deep-dwelling diapausing CVs in the SSLMP, a quadratic discriminant function analysis (QDFA) was performed. The classification algorithm was based on the carbon isotopic composition (δ 13 C) and percent carbon (%C) of individual copepods, as these variables are conservative when lipids are extracted prior to analysis. Our results suggest that about 23% of the Calanus spp. population sampled in SSLMP in late spring 2010 originated from the Saguenay Fjord (inside the SSLMP). The remainder of this population originated from regions outside the SSLMP, including the Lower St. Lawrence Estuary, and likely further east in the Gulf of St. Lawrence. Our results revealed high connectivity across the Saguenay and the St. Lawrence systems, as well as the potential for significant local production and recruitment of Calanus spp. within the Saguenay Fjord. This study also revealed the effectiveness of using δ 13 C as a marker in delineating the origin of Calanus spp., which has a relatively long non-feeding overwintering and diapausing period making it amenable to the conservation of isotopic signatures.

Dealing with lipid effects and lipid-extraction biases in δ13C and δ15N isotopic studies: a solution based on 28 marine invertebrate, fish and mammal species

“…Some isotopes such as the lighter 12 C and 14 N are naturally abundant, and generally metabolized in animal tissues and excreted preferentially over their heavier form (e.g., 13 C and 15 N; Peterson & Fry 1987, Hobson et al 1996). As a result, heavier isotopes tend to accumulate more in animal tissues relative to the lighter ones making them useful tracers of carbon sources, trophic position, and thereby of habitat use and movement patterns across isoscapes (Hobson 1999, Post 2002, Perrin et al 2014).…”

An inversion model based on salinity and remote sensing reflectance for estimating the phytoplankton absorption coefficient in the Saint Lawrence Estuary

“…The Saint Lawrence Estuary (SLE) is one of the largest estuaries in the world and is characterized by productive areas (e.g., the Saguenay Park) and the occurrence of harmful algae blooms [ Fauchot et al ., ; Perrin et al ., ]. Therefore, phytoplankton monitoring based on remote sensing techniques is crucial for proposing environmental regulations that will benefit the local communities in terms of tourism and habitat conservation.…”