Assessing movement of the California sea cucumber Parastichopus californicus in response to organically enriched areas typical of aquaculture sites

Abstract

An increasing global demand for sea cucumbers has led to interest in benthic ranching of the California sea cucumber Parastichopus californicus beneath existing aquaculture sites in British Columbia, Canada, where high levels of total organic matter (TOM) are typical. The objective of the present study was to investigate movement of P. californicus in relation to areas of increased organic content to assess the feasibility of sea cucumber ranching beneath existing aquaculture sites. A laboratory experiment using adult sea cucumbers showed that P. californicus changed their foraging behaviour based on available amounts of TOM, moving more randomly in high-TOM (~8.0%) areas and more directly in low-TOM (~1.4%) ones. They also moved more rapidly in areas with high TOM than in those with low TOM. As long as animals were exposed to high TOM, they did not abandon random movement. Because of this behaviour, aquaculture tenures may retain a population of cultured individuals, but could also attract wild individuals from the surrounding area.

Influence of flow on locomotion, feeding behaviour and spatial distribution of a suspension-feeding sea cucumber

“…Therefore, previous studies on suspension feeders in response to flow mainly focused on their feeding behaviour and body/ appendage orientation. For sea cucumbers, most behavioural studies have been conducted on deposit-feeding species, and food availability was identified as the main factor driving movement (Navarro et al, 2014;Slater et al, 2011;van Dam-Bates et al, 2016). In the present study, water flow was shown to play an important role in eliciting displacement in C. frondosa, a freemoving suspension feeder.…”

“…Finally, they represent an economically valuable, conservation-worthy marine resource that supports coastal livelihoods around the world (Anderson et al, 2011;Purcell et al, 2013). The habitat requirements, movement patterns, population densities and broad spatial distribution of sea cucumbers have previously been linked to a variety of factors including depth (Mercier et al, 2000a;Woodby et al, 2000), substratum characteristics (Dissanayake and Stefansson, 2012;Hamel and Mercier, 1996;Mercier et al, 2000a,b;Slater and Jeffs, 2010;Woodby et al, 2000;Young and Chia, 1982), food availability (Navarro et al, 2013(Navarro et al, , 2014van Dam-Bates et al, 2016), light intensity, temperature and salinity fluctuations (Navarro et al, 2014), as well as predator pressure (Slater and Jeffs, 2010). Under most circumstances, sea cucumbers are considered sedentary or sessile, although they may move in direct response to environmental conditions (Young and Chia, 1982).…”

Assessing Natural Substrates for Restricting Movement of California Sea Cucumbers Parastichopus californicus

“…One method would be to deploy benthic cages or fencing (Hannah et al. ), although mesh sizes required to contain small juvenile sea cucumbers would be so small (van Dam‐Bates ) they would potentially restrict water flow to the animals, especially under conditions of heavy biofouling. Those cages or fences would require regular maintenance by divers to ensure that they remained clean, a process that would be not only costly but potentially a hazard to divers operating underneath shellfish and/or finfish culture gear.…”

“…Those cages or fences would require regular maintenance by divers to ensure that they remained clean, a process that would be not only costly but potentially a hazard to divers operating underneath shellfish and/or finfish culture gear. Also, California sea cucumbers are adept climbers, and it could be difficult to prevent their movement over the tops of fences (van Dam‐Bates ). To maximize the uptake of farm nutrients, stocking densities, and farm profitability, it would be better to ranch sea cucumbers without confinement.…”

“…Another method to restrict sea cucumber movement within the shellfish or finfish tenure, without physical containment, might be to site farms in locations that contain undesirable substrates surrounding more desirable ones. The implication is that the undesirable substrate would act as an ecological barrier restricting sea cucumber movement, while the shell hash and increased organic levels would cause sea cucumbers to stay (van Dam-Bates et al 2016). There are three examples of sites where this method could be effective: (1) a farm that has a rocky sea floor surrounded by pre-existing soft substrates, (2) an area of soft substrate with an existing commercial shellfish farm with shell hash below the cultured bivalves, and (3) an area of soft substrates that would allow shellfish hash and/or a reef to be put in place.…”