Abstract
Deep-sea sponge grounds provide structurally complex habitat for fish and invertebrates and enhance local biodiversity. They are also vulnerable to bottom-contact fisheries and prime candidates for Vulnerable Marine Ecosystem designation and related conservation action. This study uses species distribution modeling, based on presence and absence observations of Geodia spp. and sponge grounds derived from research trawl catches, as well as spatially continuous data on the physical and biological ocean environment derived from satellite data and oceanographic models, to model the distribution of Geodia sponges and sponge grounds in the Northwest Atlantic. Most models produce excellent fits with validation data although fits are reduced when models are extrapolated to new areas, especially when oceanographic regimes differ between areas. Depth and minimum bottom salinity were important predictors in most models, and a Geodia spp. minimum bottom salinity tolerance threshold in the 34.3-34.8 psu range was hypothesized on the basis of model structure. The models indicated two currently unsampled regions within the study area, the deeper parts of Baffin Bay and the Newfoundland and Labrador slopes, where future sponge grounds are most likely to be found.
Highlights
Sponges form an ancient group of sessile filter-feeders characterized by a body plan built around a system of canals through which water is pumped, supplying food and oxygen and removing waste [1]
All models run on the subareas, except those for G. barretti and sponge grounds in the BB subarea, produced excellent fits (AUC >= 0.9; Table 4), and there were no consistent differences between the predictability of the two Geodia species, the Geodia genus, and the sponge ground habitat
The excellent fit of most models strongly supports the use of Species distribution modeling (SDM) for local mapping of both Geodia spp. sponges and sponge grounds, suggesting that these models are suitable for outlining sponge ground areas to be considered for Vulnerable Marine Ecosystem (VME) designation
Summary
Sponges form an ancient group of sessile filter-feeders characterized by a body plan built around a system of canals through which water is pumped, supplying food and oxygen and removing waste [1]. More recently the threat posed by bottom-contact fisheries has sparked conservation concern, especially in light of deep-sea sponges being slow-growing and long-lived organisms vulnerable to disturbance [3,16]. The combination of this vulnerability and their importance for deepsea benthic ecosystems makes sponge grounds a prime candidate for Vulnerable Marine Ecosystem (VME) designation as outlined in United Nations General Assembly Resolution 61/105 [17], and subject to conservation action [18]. Because deep-sea conservation of benthic species and habitats is primarily carried out through spatial fisheries management there is a need to map the distributions of sponges and sponge grounds at the level of spatial detail needed for such management
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