Hitching a ride on Hercules:fatal epibiosis drives ecosystem change from mud banks to oyster reefs

[Excerpt] Best known as a "love them or hate them" luxury food, or for their pearls, oysters are also ecosystem engineers, forming vast oyster reefs. Oyster reefs provide habitat for a myriad of species, and support fisheries, improve water quality and provide coastal protection. These services are estimated to be worth US$5,500–$99,000 per hectare per year (Grabowski et al. 2012). Globally, oyster reefs have declined by 85% through destructive overfishing, coastal development, pollution, and introduced competitors, predators and diseases (Beck et al. 2011). Active restoration is becoming an increasingly popular tool to bring back lost oyster reefs and the ecosystem services they provide (Fitzsimons et al. 2019). However, restoration is not always successful, and knowledge about how reefs naturally form and function is vital to improve restoration success. Oyster larvae only settle on hard substrates. Reefs proliferate because oyster shells provide a settlement surface, and oysters provide chemical and sound cues that facilitate larval settlement (Lillis et al. 2013). However, these reefs often form on intertidal sand and mud banks. This raises the question, how do oyster reefs form on mud banks in the absence of hard surfaces

Australian shellfish ecosystems: past distribution, current status and future direction

We review the status of marine shellfish ecosystems formed primarily by bivalves in Australia, including: identifying ecosystem-forming species, assessing their historical and current extent, causes for decline and past and present management. Fourteen species of bivalves were identified as developing complex, three-dimensional reef or bed ecosystems in intertidal and subtidal areas across tropical, subtropical and temperate Australia. A dramatic decline in the extent and condition of Australia's two most common shellfish ecosystems, developed by Saccostrea glomerata and Ostrea angasi oysters, occurred during the mid-1800s to early 1900s in concurrence with extensive harvesting for food and lime production, ecosystem modification, disease outbreaks and a decline in water quality. Out of 118 historical locations containing O. angasi-developed ecosystems, only one location still contains the ecosystem whilst only six locations are known to still contain S. glomerata-developed ecosystems out of 60 historical locations. Ecosystems developed by the introduced oyster Crasostrea gigas are likely to be increasing in extent, whilst data on the remaining 11 ecosystem-forming species are limited, preventing a detailed assessment of their current ecosystem-forming status. Our analysis identifies that current knowledge on extent, physical characteristics, biodiversity and ecosystem services of Australian shellfish ecosystems is extremely limited. Despite the limited information on shellfish ecosystems, a number of restoration projects have recently been initiated across Australia and we propose a number of existing government policies and conservation mechanisms, if enacted, would readily serve to support the future conservation and recovery of Australia's shellfish ecosystems

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Description of Australian ecosystem-forming bivalve species.

<p>Description of Australian ecosystem-forming bivalve species.</p

(A) Locality names across Australia containing the term Oyster or Limeburner (B) past and present shellfish aquaculture sites and (C) historical locations of shellfish fisheries.

<p>(A) Locality names across Australia containing the term Oyster or Limeburner (B) past and present shellfish aquaculture sites and (C) historical locations of shellfish fisheries.</p

Summary of the literature review on ecosystem-forming bivalve species by subject area.

<p>Papers were assigned to more than one category if they covered multiple subjects.</p

Summary of historical wild harvest shellfish fisheries and legislation.

<p>Summary of historical wild harvest shellfish fisheries and legislation.</p

Historical shellfish ecosystem locations deciphered from multiple lines of evidence for: (A) <i>Ostrea angasi</i> and (B) <i>Saccostrea glomerata</i>.

<p>Evidence based on: 1) Historically harvested locations 2) locality names consisting of either ‘Oyster’ or ‘Limeburner’ or 3) current commercial shellfish aquaculture (<i>S</i>. <i>glomerata</i>, <i>O</i>. <i>angasi</i> and <i>C</i>. <i>gigas only)</i>.</p

Diagrams created by Saville-Kent (1845–1908) on methods to collect wild oyster spat (Fig 2 in image) and to establish an artificial oyster reef above the seabed (Fig 3 in image).

<p>Reproduced from [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0190914#pone.0190914.ref038" target="_blank">38</a>].</p