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The diversity of life in the sea is critical to the health of ocean ecosystems that support living resources and therefore essential to the economic, nutritional, recreational, and health needs of billions of people. Yet there is evidence that the biodiversity of many marine habitats is being altered in response to a changing climate and human activity. Understanding this change, and forecasting where changes are likely to occur, requires monitoring of organism diversity, distribution, abundance, and health. It requires a minimum of measurements including productivity and ecosystem function, species composition, allelic diversity, and genetic expression. These observations need to be complemented with metrics of environmental change and socioeconomic drivers. However, existing global ocean observing infrastructure and programs often do not explicitly consider observations of marine biodiversity and associated processes. Much effort has focused on physical, chemical and some biogeochemical measurements.

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Aim To examine the global distribution, endemicity, and latitudinal gradients of species richness of razor clams, family Solenidae.Location Global.Methods A total of 3105 distribution records for 77 Solen and Solena species were used. Species richness was plotted in 5°latitude-longitude cells and related to environmental variables. ResultsThe north-west Pacific and the Indo-West Pacific have the highest species richness (about 85% of all species)-mostly in the Sea of Japan, China Sea, the Gulf of Thailand and the Andaman Sea. Cluster analysis of similarity patterns of species composition (i.e., presence of Solenidae species) for 5°latitudinal-longitudinal grid cells showed 16 significant biogeographical regions that concur with existing marine biogeographical hypotheses. More than half of the species were endemic to specific biogeographical regions. The geographical distribution of species in 5°latitudinal bands showed a significant bimodal pattern. Global patterns of species richness increased from the poles to intermediate latitudes and dipped near the equator. A non-linear relationship between species richness and mean sea-surface temperature (SST) values was compatible with this bimodal pattern. Two inflection points of species richness with correlation of SST at 12°C (low species richness) and 28°C (high species richness) were coincident with the bimodal latitudinal species richness pattern. Species richness was highly positively correlated with mean SST over all latitudes, and within the Northern and Southern Hemispheres. Species richness decreased with SST range over all latitudes and in the Northern Hemisphere. Species richness also decreased with chlorophyll-a concentration and primary productivity, but increased with ocean area in the Northern Hemisphere (only). Main conclusionsThe latitudinal distribution in species richness of Solenidae peaked at 10°N and 25°S rather than at the equator, exhibiting a strongly bimodal pattern that is likely to be temperature driven.

Video and image data are regularly used in the field of benthic ecology to document biodiversity. However, their use is subject to a number of challenges, principally the identification of taxa within the images without associated physical specimens. The challenge of applying traditional taxonomic keys to the identification of fauna from images has led to the development of personal, group, or institution level reference image catalogues of operational taxonomic units (OTUs) or morphospecies. Lack of standardisation among these reference catalogues has led to problems with observer bias and the inability to combine datasets across studies. In addition, lack of a common reference standard is stifling efforts in the application of artificial intelligence to taxon identification. Using the North Atlantic deep sea as a case study, we propose a database structure to facilitate standardisation of morphospecies image catalogues between research groups and support future use in multiple front-end applications. We also propose a framework for coordination of international efforts to develop reference guides for the identification of marine species from images. The proposed structure maps to the Darwin Core standard to allow integration with existing databases. We suggest a management framework where high-level taxonomic groups are curated by a regional team, consisting of both end users and taxonomic experts. We identify a mechanism by which overall quality of data within a common reference guide could be raised over the next decade. Finally, we discuss the role of a common reference standard in advancing marine ecology and supporting sustainable use of this ecosystem.

Global scale analyses have recently revealed that the latitudinal gradient in marine species richness is bimodal, peaking at low-mid latitudes but with a dip at the equator; and that marine species richness decreases with depth in many taxa. However, these overall and independently studied patterns may conceal regional differences that help support or qualify the causes in these gradients. Here, we analysed both latitudinal and depth gradients of species richness in the NW Pacific and its adjacent Arctic Ocean. We analysed 324,916 distribution records of 17,414 species from 0 to 10,900 m depth, latitude 0 to 90°N, and longitude 100 to 180°N. Species richness per c. 50 000 km 2 hexagonal cells was calculated as alpha (local average), gamma (regional total) and ES50 (estimated species for 50 records) per latitudinal band and depth interval. We found that average ES50 and gamma species richness decreased per 5° latitudinal bands and 100 m depth intervals. However, average ES50 per hexagon showed that the highest species richness peaked around depth 2,000 m where the highest total number of species recorded. Most (83%) species occurred in shallow depths (0 to 500 m). The area around Bohol Island in the Philippines had the highest alpha species richness (more than 8,000 species per 50,000 km 2 ). Both alpha and gamma diversity trends increased from the equator to latitude 10°N, then further decreased, but reached another peak at higher latitudes. The latitudes 60–70°N had the lowest gamma and alpha diversity where there is almost no ocean in our study area. Model selection on Generalized Additive Models (GAMs) showed that the combined effects of all environmental predictors produced the best model driving species richness in both shallow and deep sea. The results thus support recent hypotheses that biodiversity, while highest in the tropics and coastal depths, is decreasing at the equator and decreases with depth below ~2000 m. While we do find the declines of species richness with latitude and depth that reflect temperature gradients, local scale richness proved poorly correlated with many environmental variables. This demonstrates that while regional scale patterns in species richness may be related to temperature, that local scale richness depends on a greater variety of variables.

Razor clams (Pharidae and Solenidae) are deep-burrowing bivalves that inhabit shallow waters of the tropical, subtropical, and temperate seas. Using 'maximum entropy' , a species distribution modelling software, we predicted the most suitable environments for the entire family and 14 Solen species to indicate their present and future geographic distributions. Distance to land, depth, and sea surface temperature (SST) were the most important environmental variables in training and creating the present and future distribution models both at the family and species level. In the present distribution models at the family level, the most suitable environment was where distance to land was between 0 and 100 km, a depth of 0-150 m, wave height of 5-7 m, a mean chlorophyll-a concentration about 0.7 mg m −3, and mean SST between 12 and 28 °C. Comparison with the future distribution models at the species level, found that most species were predicted to shift their distribution ranges poleward under the future environmental scenarios; i.e. species in the northern hemisphere would shift northward and southern species southward. Models also predicted that half of the species would expand their distribution ranges, 29% of species would not change their distribution, and 21% of species would shrink their distribution ranges under future climate change. Expanding geographic ranges would result in overlap in species ranges and thus greater species richness at regional scales. Model results predict that the mid-latitude peaks of species richness will move further apart, increasing the dip in richness near the equator, due to global climate change.

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