Spatially congruent sites of importance for global shark and ray biodiversity

Abstract

Many important areas identified for conservation priorities focus on areas of high species richness, however, it is unclear whether these areas change depending on what aspect of richness is considered (e.g. evolutionary distinctiveness, endemicity, or threatened species). Furthermore, little is known of the extent of spatial congruency between biodiversity measures in the marine realm. Here, we used the distribution maps of all known marine sharks, rays, and chimaeras (class Chondrichthyes) to examine the extent of spatial congruency across the hotspots of three measures of species richness: total number of species, evolutionarily distinct species, and endemic species. We assessed the spatial congruency between hotspots considering all species, as well as on the subset of the threatened species only. We consider three definitions of hotspot (2.5%, 5%, and 10% of cells with the highest numbers of species) and three levels of spatial resolution (1˚, 4˚, and 8˚grid cells). Overall, we found low congruency among all three measures of species richness, with the threatened species comprising a smaller subset of the overall species patterns irrespective of hotspot definition. Areas of congruency at 1˚and 5% richest cells contain over half (64%) of all sharks and rays and occurred off the coasts of: (1) Northern Mexico Gulf of California, (2) USA Gulf of Mexico, (3) Ecuador, (4) Uruguay and southern Brazil, (5) South Africa, southern Mozambique, and southern Namibia, (6) Japan, Taiwan, and parts of southern China, and (7) eastern and western Australia. Coarsening resolution increases congruency twofold for all species but remains relatively low for threatened measures, and geographic locations of congruent areas also change. Finally, for pairwise comparisons of biodiversity measures, evolutionarily distinct species richness had the highest overlap with total species richness regardless of resolution or definition of hotspot. We suggest that focusing conservation attention solely on areas of high total species richness will not necessarily contribute efforts towards species that are most at risk, nor will it protect other important dimensions of species richness.

Ghosts of the deep – Biodiversity, fisheries, and extinction risk of ghost sharks

“…Species richness was highest in the Northeast Atlantic, off the northwest coast of Africa (Morocco to Mauritania), followed by the East China Sea, New Zealand and off the northwest coast of South America (Ecuador and Peru) (Figure 3a). Patterns of ghost shark richness follow similar patterns to that of chondrichthyan total species richness and evolutionarily distinct species richness (Derrick et al., 2020). A notable exception is the Northeast Atlantic region where ghost shark richness was relatively high, but relatively low for all chondrichthyans.…”

Post-2020 Kunming 30% target can easily protect all endemic sharks and rays in the Western Indian Ocean and more

“…Our calculations may be conservative because there are a number of established MPAs in the region (primarily in South Africa), currently lacking IUCN protected area category designations 12 , that could not be included in our analysis. These unclassified MPAs likely contribute some biodiversity and conservation value for endemic sharks and rays, particularly as South Africa is well-known as a regional marine biodiversity hotspot 23,25,43 . Nevertheless, empirical evidence persists that existing protected areas do a poor job for biodiversity, despite substantial recent increases in protected area coverage 44,45 .…”

“…The WIO region, defined here to include sub-equatorial Africa (from the Angola-Namibia border to the Kenya-Somalia border) and the Arabian Sea and adjacent waters region (from the Kenya-Somalia border to the easternmost Sri Lanka border), harbours the second greatest biodiversity hotspot for marine fish and invertebrates 22,23 . This global hotspot is across multiple dimensions of biodiversity (e.g., species richness, evolutionary distinctiveness, endemicity 24 ), including for sharks and rays 15,22,25 . In this region, coastal nations and communities are heavily dependent on marine resources, which include important shark and ray fisheries.…”

Using natural history collections to investigate changes in pangolin (Pholidota: Manidae) geographic ranges through time

“…Geographical analyses are often based on summarising data within grid cells of a defined size, then using values for each grid cell as input data for downstream analysis (e.g., Derrick, Cheok & Dulvy, 2020 ). We downloaded historical and current human population size data as population count and population density from the History Database of the Global Environment (HYDE v3.2.1; Goldewijk et al, 2017 ) at 5′ or 0.083 degree resolution.…”