Roger J.H. Herbert

Comparison of sediment quality guidelines (SQGs) for the assessment of metal contamination in marine and estuarine environments

Sediment quality guidelines (SQGs) are an important tool for the assessment of contamination in marine and estuarine sediments. Although such guidelines are not definitive indicators of toxicity, they can have a high predictive ability and are a vital tool for identifying areas with potentially adverse biological effects. In the present study, 15 sets of common SQGs have been compared, including values for Australia/New Zealand, Canada, Hong Kong, Norway, the Netherlands, the USA and regions within the USA (Puget Sound/Washington, New York and Florida). The majority of these SQGs are based on the weight-of-evidence approach. In particular, the sub-group of TEL/PEL-based values have a very high degree of comparability; values not belonging to this uniform group show substantial variations.

Influence of recruitment and temperature on distribution of intertidal barnacles in the English Channel

Many warm-water (Lusitanian) species reach their limits in the central English Channel, failing to penetrate to the North Sea. We re-surveyed the eastern limits of the Lusitanian intertidal barnacles Chthamalus montagui and C. stellatus, from 1994 to 2004, a decade of exceptionally high sea temperatures, and found range extensions on both sides of the Channel compared to the 1950s and 1970s. Annual recruitment of Chthamalus on the English coast was monitored. There was a consistent gradient of low recruitment to the east of Portland Bill, with significant reductions coinciding with prominent headlands. Highest recruitment occurred during the warmest years. Cluster analysis showed a high degree of similarity of annual recruitment within coastal cells suggesting that local processes are also important. In 1999 we compared recruitment in the other common intertidal barnacles, the boreal Semibalanus balanoides and the non-native Elminius modestus, with Chthamalus spp. All species showed low recruitment between Selsey Bill and Portland Bill, suggesting habitat limitations and/or hydrographic mechanisms. Annual recruitment of Chthamalus at existing limits on the Isle of Wight was positively correlated with the number of days of westerly and south-westerly winds during the summer, coinciding with the pelagic larval phase. A ‘pulse’ of high Chthamalus recruitment on the Isle of Wight, measured during the warm summer of 2000, reversed population decline. Only a higher frequency of such pulses will maintain populations at existing limits and increase the rate of range extension towards the North Sea. Such extension will be limited by lack of hard substrata, but proliferation of coastal defence schemes in recent years is increasing suitable habitat for barnacles.

Ecological impacts of non-native Pacific oysters (Crassostrea gigas) and management measures for protected areas in Europe

Pacific oysters are now one of the most ‘globalised’ marine invertebrates. They dominate bivalve aquaculture production in many regions and wild populations are increasingly becoming established, with potential to displace native species and modify habitats and ecosystems. While some fishing communities may benefit from wild populations, there is now a tension between the continued production of Pacific oysters and risk to biodiversity, which is of particular concern within protected sites. The issue of the Pacific oyster therefore locates at the intersection between two policy areas: one concerning the conservation of protected habitats, the other relating to livelihoods and the socio-economics of coastal aquaculture and fishing communities. To help provide an informed basis for management decisions, we first summarise evidence for ecological impacts of wild Pacific oysters in representative coastal habitats. At local scales, it is clear that establishment of Pacific oysters can significantly alter diversity, community structure and ecosystem processes, with effects varying among habitats and locations and with the density of oysters. Less evidence is available to evaluate regional-scale impacts. A range of management measures have been applied to mitigate negative impacts of wild Pacific oysters and we develop recommendations which are consistent with the scientific evidence and believe compatible with multiple interests. We conclude that all stakeholders must engage in regional decision making to help minimise negative environmental impacts, and promote sustainable industry development.

The regional recovery of Nucella lapillus populations from marine pollution, facilitated by man-made structures

The dogwhelk Nucella lapillus experienced localized extinction in the 1980s and 1990s due to the use of tributyltin (TBT) antifoulants, causing imposex in females. The aim of this study was to establish the extent of the return of the species across the mainland coast of central southern England as TBT use has been progressively restricted, and to quantify the extent of imposex impact on the populations present. We surveyed from Poole to Selsey where isolated populations had become extinct, and the Isle of Wight where some populations had persisted. We found evidence that since TBT restrictions, recolonization and colonization by N. lapillus has been rapid. By 2007–2008, of the eleven surveyed mainland sites, seven were colonized, although indications of reduced imposex impacts were mixed. Distribution had also extended on the Isle of Wight and populations were larger with less imposex impact in sites with long term populations. The lack of continuous suitable habitat blocks and the hydrodynamic complexity of the region, leads us to hypothesize that recovery has been facilitated by man-made structures which may be acting as ‘stepping stones’. Populations that have become established on engineered structures such as sea walls, breakwaters and rock groynes demonstrate accelerated recovery in the region as TBT in the environment has generally declined. Sites with suitable substrates and food sources near to ports were either not recolonized or had small populations with imposex evident. For species with a short pelagic larval stage or with direct development, population connectivity between patches of harder substrata along hydrodynamically complex coastlines may be greater than previously thought.

Introduction, dispersal and naturalization of the Manila clam Ruditapes philippinarum in British estuaries, 1980–2010

The introduction of the Manila clam into British coastal waters in the 1980s was contested by conservation agencies. While recognizing the value of the clam for aquaculture, the government decided that it posed no invasive risk, as British sea temperatures would prevent naturalization. This proved incorrect. Here we establish the pattern of introduction and spread of the species over the first 30 years of its presence in Britain. We report archival research on the sequence of licensed introductions and examine their relationship in time and space to the appearance of wild populations as revealed in the literature and by field surveys. By 2010 the species had naturalized in at least 11 estuaries in southern England. These included estuaries with no history of licensed introduction. In these cases activities such as storage of catch before market or deliberate unlicensed introduction represent the probable mechanisms of dispersal. In any event naturalization is not an inevitable consequence of introduction and the chances of establishment over the period in question were finely balanced. Consequently in Britain the species is not currently aggressively invasive and appears not to present significant risk to indigenous diversity or ecosystem function. However it is likely to gradually continue its spread should sea surface temperatures rise as predicted.

Dispersal and mobility of metal contamination across a salt marsh from coastal landfill sites using ammonium nitrate extractions as an indicator.

Landfills have been the primary method of waste disposal within the UK for many years, and are often associated with land reclamation. The landfill in Christchurch Harbour, considered in this study, has a straight artificial channel which runs from the edge of the landfill to the estuary. This channel has increased the levels of metals in the marshland and acts, in effect, as a drainage system. The degree of metal mobility in soils and sediments is typically determined by using sequential extraction schemes (SESs), but the effectiveness and precision of these procedures are disputed. A simpler and more resilient approach is the application of partial/single extraction schemes (PESs). Both schemes, however, can only assess the theoretical readiness of a metal to migrate at a certain time/place and under certain conditions-they do not gauge the actual migration and therefore can only have predictive abilities at best. In this study, the metal distribution in an intertidal area between a landfill and an estuary has been determined using the actual distribution patterns in the ground and comparing them with the theoretical mobility based on the standardised PES procedure DIN 19730. It was found that this procedure can predict the actual migration in the marshland rather well; however, in the vicinity of the channel no correlation between the mobility and dispersion could be detected and the actual movement is much higher than the PES outcomes generally indicated.

Epibenthic and mobile species colonisation of a geotextile artificial surf reef on the south coast of England

With increasing coastal infrastructure and use of novel materials there is a need to investigate the colonisation of assemblages associated with new structures, how these differ to natural and other artificial habitats and their potential impact on regional biodiversity. The colonisation of Europe’s first artificial surf reef (ASR) was investigated at Boscombe on the south coast of England (2009–2014) and compared with assemblages on existing natural and artificial habitats. The ASR consists of geotextile bags filled with sand located 220m offshore on a sandy sea bed at a depth of 0-5m. Successional changes in epibiota were recorded annually on differently orientated surfaces and depths using SCUBA diving and photography. Mobile faunal assemblages were sampled using Baited Remote Underwater Video (BRUV). Distinct stages in colonisation were observed, commencing with bryozoans and green algae which were replaced by red algae, hydroids and ascidians, however there were significant differences in assemblage structure with depth and orientation. The reef is being utilised by migratory, spawning and juvenile life-history stages of fish and invertebrates. The number of non-native species was larger than on natural reefs and other artificial habitats and some occupied a significant proportion of the structure. The accumulation of 180 benthic and mobile taxa, recorded to date, appears to have arisen from a locally rich and mixed pool of native and non-native species. Provided no negative invasive impacts are detected on nearby protected reefs the creation of novel yet diverse habitats may be considered a beneficial outcome.

Performance and Habitat of the Mantis Shrimp Rissoides desmaresti (Stomatopoda: Squillidae) Near the Range Border on the South Coast of England

Abstract Performance related traits and habitat of the mantis shrimp Rissoides desmaresti are described for specimens collected from the Solent region on the south coast of England, close to the species northern border. Most animals were collected over sub tidal ‘mud’ and ‘sandy mud’ sediments, although new recruits and adults were also found on intertidal mudflats. Winter size-frequency distributions showed evidence of regular recruitment and growth to maturity. The reproductive condition of females was staged according to the colour of cement glands, which developed synchronously with ovaries. Females with ripe ovaries were observed between October and April and animals kept in aquaria deposited and brooded eggs in March and April. Results showed that regular recruitment and large breeding populations can occur close to range borders.