Aquatic Environment and Biodiversity Annual Review 2012

AEBAR 2012: Marine Biodiversity
among distinct species, providing new insight into the genetic structure of marine diversity. With the
genetic analysis often called barcoding, the Census sometimes decreased diversity but generally its
analyses expanded the number of species, especially the number of different microbes, including
bacteria and archaea.
The Census has overwhelmingly demonstrated that the total number of species in the ocean remain
largely unknown. The Census also demonstrated that evidence of human impacts on the oceans
extends to all depths and habitats and that we still have much to learn to integrate use of resources
with stewardship of a healthy marine ecosystem. The Census results could logically extrapolate to at
least a million kinds of eukaryotic marine life that earn the rank of species and to tens or even
hundreds of millions of kinds of microbes.
A summary of the overall state of knowledge about marine biodiversity after the Census by Costello
et al. (2010) places New Zealand 6 th out of 18 national regions based on the collective knowledge
assembled by the Census National and Regional Implementation Committees (NRIC) and comparing
the Spearman rank correlation coefficients between known diversity (total species richness, alien
species, and endemics) and available resources, such as numbers of taxonomic guides and experts.
(Figure 11.2).
Figure 11.2: The regions are ranked by their state-of-knowledge index (mean ± standard error) across taxa. Dashed
line represents the overall mean. (Image Source Costello et al. 2010).
All NRICs reported what they considered the main threats to marine biodiversity in their region,
citing published data and expert opinions. Although the reports were not standardised, the threats
identified were grouped into several overarching issues. We integrated these data on biodiversity
threats so as to rank each threat from 1 (very low) to 5 (very high threat) in each region. New Zealand
was placed 12 th out of 1 8 regions in terms of overall threat levels to biodiversity, overfishing and
alien species invasion. Habitat loss and ocean acidification were identified as the biggest threats to
marine biodiversity in New Zealand (Costello et al. 2010).
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