Callum M. Roberts

The biodiversity of species and their rates of extinction, distribution, and protection

Background A principal function of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) is to “perform regular and timely assessments of knowledge on biodiversity.” In December 2013, its second plenary session approved a program to begin a global assessment in 2015. The Convention on Biological Diversity (CBD) and five other biodiversity-related conventions have adopted IPBES as their science-policy interface, so these assessments will be important in evaluating progress toward the CBD’s Aichi Targets of the Strategic Plan for Biodiversity 2011–2020. As a contribution toward such assessment, we review the biodiversity of eukaryote species and their extinction rates, distributions, and protection. We document what we know, how it likely differs from what we do not, and how these differences affect biodiversity statistics. Interestingly, several targets explicitly mention “known species”—a strong, if implicit, statement of incomplete knowledge. We start by asking how many species are known and how many remain undescribed. We then consider by how much human actions inflate extinction rates. Much depends on where species are, because different biomes contain different numbers of species of different susceptibilities. Biomes also suffer different levels of damage and have unequal levels of protection. How extinction rates will change depends on how and where threats expand and whether greater protection counters them. Different visualizations of species biodiversity. (A) The distributions of 9927 bird species. (B) The 4964 species with smaller than the median geographical range size

Benefits beyond boundaries: the fishery effects of marine reserves

Marine reserves are areas of the sea where fishing is not allowed. They provide refuges where populations of exploited species can recover and habitats modified by fishing can regenerate. In some places, closed areas have been used for fisheries management for centuries [1] and, until recently, natural refugia also existed, inaccessible through depth, distance or adverse conditions. Developments in technology have left few areas of fishing interest beyond our reach. Recently, the idea of marine reserves as fisheries management tools has re-emerged with developing interest in ecosystembased management, and observations of incidental fisheries benefits from reserves established for conservation. In light of new evidence, we argue that, by integrating large-scale networks of marine reserves into fishery management, we could reverse global fishery declines and provide urgently needed protection for

ECOLOGICAL CRITERIA FOR EVALUATING CANDIDATE SITES FOR MARINE RESERVES

Several schemes have been developed to help select the locations of marine reserves. All of them combine social, economic, and biological criteria, and few offer any guidance as to how to prioritize among the criteria identified. This can imply that the relative weights given to different criteria are unimportant. Where two sites are of equal value ecologically; then socioeconomic criteria should dominate the choice of which should be protected. However, in many cases, socioeconomic criteria are given equal or greater weight than ecological considerations in the choice of sites. This can lead to selection of reserves with little biological value that fail to meet many of the desired objectives. To avoid such a possibility, we develop a series of criteria that allow preliminary evaluation of candidate sites according to their relative biological values in advance of the application of socioeconomic criteria. We include criteria that,. while not strictly biological, have a strong influence on the species present or ecological processes. Out scheme enables sites to be assessed according to their biodiversity, the processes which underpin that diversity, and the processes that support fisheries and provide a spectrum of other services important to people. Criteria that capture biodiversity values include biogeographic representation, habitat representation and heterogeneity, and presence of species or populations of special interest (e.g., threatened species). Criteria that capture sustainability of biodiversity and fishery values include the size of reserves necessary to protect viable habitats, presence of exploitable species, vulnerable life stages, connectivity among reserves, links among ecosystems, and provision of ecosystem services to people. Criteria measuring human and natural threats enable candidate sites to be eliminated from consideration if risks are too great, but also help prioritize among sites where threats can be mitigated by protection. While our criteria can be applied to the design of reserve networks, they also enable choice of single reserves to be made in the context of the attributes of existing protected areas. The overall goal of our scheme is to promote the development of reserve networks that will maintain biodiversity and ecosystem functioning at large scales. The values of eco-system goods and services for people ultimately depend on meeting this objective.

Extinction risk in the sea

Jean Baptiste de Lamarck and Thomas Huxley, two of the foremost thinkers of the 18th and 19th centuries, believed that humanity could not cause the extinction of marine species. Their opinions reflected a widespread belief that the seas were an inexhaustible source of food and wealth of which people could barely use a fraction. Such views were given weight by the abundant fisheries of the time. Additionally, the incredible fecundity and wide distributions of marine fishes, combined with limited exploitation, provided ample justification for optimism. The ideas of Huxley and Lamarck persist to this day, despite a sea change in the scale and depth of our influence on the oceans. Marine species could be at a far greater risk of extinction than we have assumed.

The role of marine reserves in achieving sustainable fisheries

Many fishery management tools currently in use have conservation value. They are designed to maintain stocks of commercially important species above target levels. However, their limitations are evident from continuing declines in fish stocks throughout the world. We make the case that to reverse fishery declines, safeguard marine life and sustain ecosystem processes, extensive marine reserves that are off limits to fishing must become part of the management strategy. Marine reserves should be incorporated into modern fishery management because they can achieve many things that conventional tools cannot. Only complete and permanent protection from fishing can protect the most sensitive habitats and vulnerable species. Only reserves will allow the development of natural, extended age structures of target species, maintain their genetic variability and prevent deleterious evolutionary change from the effects of fishing. Species with natural age structures will sustain higher rates of reproduction and will be more resilient to environmental variability. Higher stock levels maintained by reserves will provide insurance against management failure, including risk–prone quota setting, provided the broader conservation role of reserves is firmly established and legislatively protected. Fishery management measures outside protected areas are necessary to complement the protection offered by marine reserves, but cannot substitute for it.

Application of ecological criteria in selecting marine reserves and developing reserve networks

Marine reserves are being established worldwide in response to a growing recognition of the conservation crisis that is building in the oceans. However, designation of reserves has been largely opportunistic, or protective measures have been implemented (often overlapping and sometimes in conflict) by different entities seeking to achieve dif- ferent ends. This has created confusion among both users and enforcers, and the proliferation of different measures provides a false sense of protection where little is offered. This paper sets out a procedure grounded in current understanding of ecological processes, that allows the evaluation and selection of reserve sites in order to develop functional, interconnected networks of fully protected reserves that will fulfill multiple objectives. By fully protected we mean permanently closed to fishing and other resource extraction. We provide a frame- work that unifies the central aims of conservation and fishery management, while also meeting other human needs such as the provision of ecosystem services (e.g., maintenance of coastal water quality, shoreline protection, and recreational opportunities). In our scheme, candidate sites for reserves are evaluated against 12 criteria focused toward sustaining the biological integrity and productivity of marine systems at both local and regional scales. While a limited number of sites will be indispensable in a network, many will be of similar value as reserves, allowing the design of numerous alternative, biologically adequate net- works. Devising multiple network designs will help ensure that ecological functionality is preserved throughout the socioeconomic evaluation process. Too often, socioeconomic cri- teria have dominated the process of reserve selection, potentially undermining their efficacy. We argue that application of biological criteria must precede and inform socioeconomic evaluation, since maintenance of ecosystem functioning is essential for meeting all of the goals for reserves. It is critical that stakeholders are fully involved throughout this process. Application of the proposed criteria will lead to networks whose multifunctionality will help unite the objectives of different management entities, so accelerating progress toward improved stewardship of the oceans.

Ecological advice for the global fisher crisis.

Fisheries science was the precursor of population ecology and continues to contribute important theoretical advances. Despite this, fishery scientists have a poor record for applying their insights to real-world fisheries management. Is there a gulf between theory and application or does the high variability inherent in fish populations and complexity of multispecies fisheries demand a different approach to management? Perhaps the solution to the world fisheries crisis is obvious after all?

Rapidly shifting environmental baselines among fishers of the Gulf of California

Shifting environmental baselines are inter-generational changes in perception of the state of the environment. As one generation replaces another, peoples perceptions of what is natural change even to the extent that they no longer believe historical anecdotes of past abundance or size of species. Although widely accepted, this phenomenon has yet to be quantitatively tested. Here we survey three generations of fishers from Mexicos Gulf of California (N=108), where fish populations have declined steeply over the last 60 years, to investigate how far and fast their environmental baselines are shifting. Compared to young fishers, old fishers named five times as many species and four times as many fishing sites as once being abundant/productive but now depleted (Kruskal–Wallis tests, both p<0.001) with no evidence of a slowdown in rates of loss experienced by younger compared to older generations (Kruskall-Wallis test, NS in both cases). Old fishers caught up to 25 times as many Gulf grouper Mycteroperca jordani as young fishers on their best ever fishing day (regression r2=0.62, p<0.001). Despite times of plentiful large fish still being within living memory, few young fishers appreciated that large species had ever been common or nearshore sites productive. Such rapid shifts in perception of what is natural help explain why society is tolerant of the creeping loss of biodiversity. They imply a large educational hurdle in efforts to reset expectations and targets for conservation.

Deep impact: the rising toll of fishing in the deep sea

The deep ocean is one of the last great wildernesses. Waters deeper than 1000 m cover an estimated 62% of the planet. In spite of more than 150 years of exploration, the ocean depths remain virtually unknown. Biological science has so far touched upon only one millionth of the deep-sea floor, but new technology is revealing unknown and exotic habitats as quickly as we look. Those technologies are also bringing the deep within reach of industry, with devastating consequences.

Effects of recreational SCUBA diving on fore-reef slope communities of coral reefs

Abstract This study investigated the effects of recreational SCUBA diving on the fore-reef slopes of coral reefs near Sharm-el-Sheikh, a popular resort in Egypt. Benthic communities were compared using randomly placed 1-m2 quadrats at three sites subdivided into heavily and little dived areas. There were significantly more damaged coral colonies, loose fragments of live coral, fragments of coral re-attached to the substratum, partially dead and abraded corals in areas heavily used by divers than in control areas. Damage to corals varied with growth form, branching forms being most vulnerable to breakage. Changes to communities at heavily and little dived sites were studied over 12 months using 3 × 3 m permanent quadrats. No significant increases in damage attributable to diving were detected for the three sites combined. However, when considered individually, the site which had experienced the greatest increase in diving appeared to have accumulated damage (broken coral) whereas the two others did not. For management purposes the results show that some reefs can sustain heavy levels of diving without apparent continued degradation. New dive sites can accumulate damage very rapidly. However, at the levels of diver use encountered during this study this may be more of an aesthetic than a biological problem.