A novel platform for monitoring gelatinous mesozooplankton: The high‐speed Gulf VII sampler quantifies gelatinous mesozooplankton similar to a ring net

Abstract

Our understanding of the distribution and abundance of gelatinous mesozooplankton (0.2-20 mm) has been largely determined from the deployment of net sampling devices. Although zooplankton nets have been shown to underrepresent the abundance of certain gelatinous taxa in comparison to data from optical systems, nets still provide relative abundances for gelatinous zooplankton. A potential source of standardized, long-term, and broad-scale data for the relative abundance and distribution of gelatinous mesozooplankton is from fisheries monitoring programs which use zooplankton samplers such as the high-speed Gulf VII sampler to capture fish eggs and larvae in shelf and offshore waters. To evaluate the use of the Gulf VII sampler as a source of gelatinous mesozooplankton data, this study collected zooplankton samples using both a Gulf VII sampler and a vertical ring net at 15 stations off the northwest Irish and Scottish coasts in July 2017. The difference in the estimates of gelatinous mesozooplankton abundance and taxon richness of the Gulf VII and the ring net samples were not significant (mean abundance: Gulf VII = 135.7 AE 79.7 ind. m −3 , ring net = 149.7 AE 66.5 ind. m −3 ; taxon richness: Gulf VII = 15.2 AE 2.4, ring net = 15.4 AE 2.5), although the Gulf VII underestimated the abundance of the appendicularian Oikopleura sp. by a factor of 9.7 when compared to the ring net. Our findings describe how added value can be provided to already existing zooplankton monitoring programs while enhancing the temporal and spatial coverage of data available for gelatinous mesozooplankton.

The Ocean's labile DOC supply chain

“…Uncertainty in the parameter is associated with sampling techniques that exclude small copepods (Turner 2004), overrepresentation of coastal areas in data gathering (Schmoker et al 2013), complexity imposed by diel migration (Calbet 2001; Schmoker et al 2013; Steinberg and Landry 2017), and the uncertainties regarding the number of trophic transfers occurring within the zooplankton community. For the gelatinous mesozooplankton that bloom in coastal waters, such as jelly fish, ctenophores, and planktonic tunicates (Deibel 1988; Paffenhöfer et al 1995; Walters et al 2019; Ishak et al 2020), damage during sampling is common (Hosia et al 2017; Long et al 2020) and likely leads to an underestimate of their contributions to grazing and thus their role in labile DOC release.…”