First World Oceans Report

(Sixth in a series)

22 scientists from around the world—including Silliman University’s Hilconida Calumpong, Ph.D.—commissioned by the UN General Assembly to form the Ad Hoc Working Group  on the Regular Process for Global Reporting and Assessment of the State of the Marine Environment, including Socioeconomic Aspects, submitted the First World Oceans Report, which was adopted by the UN General Assembly in December 2015. Here are some excerpts.

Patterns of biodiversity

A basic, but key, conclusion of the present assessment is that there are clear patterns of biodiversity, both globally and regionally.

Perhaps the most common large-scale biodiversity pattern on the planet is the “latitudinal gradient,” typically expressed as a decline in the variety of species from the equator to the poles. Adherence to that pattern varies among marine taxa. Although coastal species generally peak in abundance near the equator and decline towards the poles, seals show the opposite pattern. Furthermore, strong longitudinal gradients (east-west) complicate patterns, with hotspots of biodiversity across multiple species groups in the coral triangle of the Indo-Pacific, in the Caribbean and elsewhere. 

Oceanic organisms, such as whales, differ in pattern entirely, with species numbers consistently peaking at mid-latitudes between the equator and the poles. This pattern defies the common equator-pole gradient, suggesting that different factors are at play.

However, across all groups studied, ocean temperature is consistently related to species diversity, making the effects of climate change likely to be felt as a restructuring factor of marine community diversity.

Implications

Locations of biodiversity hotspots and their relationship to the location of high levels of ecosystem services

Although marine life is found everywhere in the ocean, biodiversity hotspots exist where the number of species and the concentration of biotas are consistently high relative to the adjacent areas.  Key drivers of biodiversity are complex three-dimensional physical structures that create a diversity of physical habitats (associated with rocky sea floors), dynamic oceanographic conditions causing higher bottom-up productivity, effects of land-based inputs extending far out to sea (such as the inputs from the River Amazon) and special vegetation features creating unique and productive habitats near the shore. Those complex habitats, however, are often highly vulnerable to disturbance.

The high relative and absolute biodiversity of those hotspots often directly supports the extractive benefits of fishing and other harvests, providing a direct link between biodiversity and the provision of services by the ocean. 

Hotspots for primary productivity are necessarily also hotspots for production of oxygen as a direct result of photosynthesis. Furthermore, underlying the high biodiversity is often a high structural complexity of the habitats that support it. That structure often contributes other services, such as coastal protection and regeneration. In addition, it is the concentrated presence of iconic species in an area which adds to aesthetic services (supporting tourism and recreation) and spiritual and cultural services.

Biodiversity and economic activity

Sometimes, because of the special physical features that contribute to high biodiversity, and sometimes because of the concentration of biodiversity itself, many societies and industries are most active in areas that are also biodiversity hotspots. As on land, humanity has found the greatest social and economic benefits in the places in the ocean that are highly productive and structurally complex. For example, 22 of the 32 largest cities in the world are located on estuaries; mangroves and coral reefs support small-scale fisheries in developing countries.  Biodiversity hotspots tend to attract human uses and become socioeconomic hotspots. Hence biodiversity-rich areas have a disproportionately high representation of ports and coastal infrastructure, other intensive coastal land uses, fishing activities and aquaculture. This is one of the major challenges to the sustainable use of marine biodiversity. – Excerpted by SU Research and Environmental News Service.