Life in the Fast Lane: Modeling the Fate of Glass Sponge Larvae in the Gulf Stream

Abstract

Effective conservation management of deep-sea sponges, including design of appropriate marine protected areas, requires an understanding of the connectivity between populations throughout a species’ distribution. We provide the first consideration of larval connectivity among deep-sea sponge populations along the southeastern coast of North America, illustrate the influence of the Gulf Stream on dispersal, and complement published distribution models by evaluating colonization potential. Connectivity among known populations of the hexactinellid sponge Vazella pourtalesii was simulated using a 3-D biophysical dispersal model throughout its distribution from Florida, United States to Nova Scotia, Canada. We found no exchange with an estimated pelagic larval duration of 2 weeks between populations north and south of Cape Hatteras, North Carolina at surface, mid-water and seabed release depths, irrespective of month of release or application of a horizontal diffusion constant specific to cross-Gulf Stream diffusivity. The population north of Cape Hatteras and south of Cape Cod was isolated. There was some evidence that Gulf Stream eddies formed near Cape Hatteras could travel to the northwest, connecting the populations in the two sub-regions, however that would require a much longer pelagic duration than what is currently known. More likely almost all larval settlement will be in the immediate area of the adults. At sub-regional scales, connectivity was found from the Strait of Florida through to the Blake Plateau, southeastern United States, with the latter area showing potential for recruitment from more than one source population. The influence of the Charleston Bump, a shallow feature rising from the Blake Plateau, was substantial. Particles seeded just north of the Bump were transported greater distances than those seeded to the south, some of which were caught in an associated gyre, promoting retention at the seabed. To the north on the Scotian Shelf, despite weaker currents and greater distances between known occurrences, unidirectional transport was detected from Emerald Basin to the Northeast Channel between Georges and Browns Banks. These major conclusions remained consistent through simulations run with different averaging periods for the currents (decades to daily) and using two ocean model products (BNAM and GLORYS12V1).

Distribution and predicted climatic refugia for a reef‐building cold‐water coral on the southeast US margin

“…That is, will larvae be able to track the lines in Figure 12b at sufficient speeds to allow recruitment to more accommodating habitat, or will the western‐most populations face extirpation? Particle release models of the hexactinellid sponge Vazella pourtalesii , which commonly co‐occurs with L. pertusa , suggest that larval exchange may be partially split among the eastern Blake Plateau and the shallower sites on the upper shelf (Wang et al, 2021). However, genetic evidence indicates that L. pertusa populations on the Blake Plateau are mixed (Morrison et al, 2011), suggesting connectivity whereas Northeast Atlantic populations appear to recruit locally with differentiation apparent between certain sub‐populations (e.g., fjords vs. offshore banks; Le Goff‐Vitry et al, 2004).…”

Predicting the effects of climate change on deep‐water coral distribution around New Zealand—Will there be suitable refuges for protection at the end of the 21st century?

“…Furthermore, this review should consider the current status of the coral habitat following decades of damage by bottom trawling, which could also affect the suitability of future habitat for deep‐water coral taxa. With substantial predicted shifts in areas of primary suitable habitat it would also be useful to account for connectivity pathways (Kenchington et al, 2019 ; Wang et al, 2021 ), especially as these corals are reliant on larval dispersal for colonising new areas (Andrello et al, 2015 ; Baco et al, 2016 ; Hilário et al, 2015 ). Such a review can be undertaken using spatial planning software, for example, Zonation (Moilanen, 2007 ) and Marxan (Ball & Possingham, 2000 ), which enables consideration of multiple factors alongside the predicted spatial distribution of habitat suitability for the protected corals produced in this study.…”

Genetic diversity and connectivity of chemosynthetic cold seep mussels from the U.S. Atlantic margin

“…We hypothesize that Gulf Stream meanders and eddies could entrain bathymodioline larvae and advect them back to the Mid-Atlantic margin, enabling periodic local recruitment. Similarly, larval dispersal models for the glass sponge Vasella pourtalesii indicated low dispersal distances and high retention for a population simulated in this region [72]. Chemical cues from the chemosynthetic environment could subsequently trigger bathymodioline larvae to settle onto the benthos (see [73]).…”