Ecological role of an offshore industry artificial structure

Decommissioning of oil and gas infrastructure globally has focused attention on its importance as hard substratum on continental shelf and slope habitats. Observational studies are needed to improve understanding of faunal assemblages supported by offshore infrastructure and better predict the effect of removal. Here, we present results from visual inspection and physical sampling of a small oil and gas industry structure decommissioned from an oil field in the North East Atlantic. This is supported by observations of similar structures nearby and by photographs of the surrounding seabed from environmental baseline surveys. The structure supported a reasonably high biomass and diversity of invertebrates (>10 kg and >39 macrofaunal and 17 megafaunal species) and fishes (>20 kg biomass and >4 species). The invertebrate megafaunal species present on the structure were a sub-set of the hard substratum fauna observed on surrounding seabed. Porifera were absent from the structure. Biological succession in the first 2 years occurred as follows. Sparse colonies of the hydroid Obelia sp. stet were early colonisers then subsequent development of thick hydroid turf (Obelia sp. stet. and Halecium sp. stet.) supported an invertebrate assemblage (2654 individuals kg wet mass–1) dominated by saddle oysters [Pododesmus squama (Gmelin, 1791) and Heteranomia sp. stet.)] and scale worms (Harmothoe spp.). Percentage cover of hydroid turf varied significantly over the structure, with most growth on sections exposed to strongest currents. Commercially important fish species present around the structure included Gadus morhua (Atlantic cod), Pollachius virens (saithe) and Lophius piscatorius (monkfish). Studies of artificial structures such as this provide much needed data to understand their role in the ecology of seafloor habitats and inform environmental decision making on all stages of industry from exploration to decommissioning. We show that the ecological role of the decommissioned three-dimensional structures was to enhance the biomass of a sub-set of epifaunal invertebrates found in the area. This supported diverse associated macrofaunal organisms, providing a food source for motile invertebrates and fishes in an area where background hard substratum can be lost through the impacts of drilling

Untangling the effects of fishing effort and environmental variables on benthic communities of commercially fished scallop grounds

The Isle of Man fishing industry is currently predominated by two lucrative and heavily exploited scallop fisheries, targeting Pecten maximus and Aequipecten opercularis. The impacts of which have previously been investigated, however without the addition of environmental information. This thesis represents a unique long-term investigation into the impacts of fishing pressure and environmental variables on the benthic invertebrate communities of fishing grounds found around the Isle of Man. A significant positive trend in seawater temperature was found, along with an inverse correlation with chlorophyll-α. Fishing pressure was found to have a small, significant negative effect on indices of diversity; however environmental variables were unable to explain the remaining patterns in diversity. The composition of each of the benthic communities was then investigated in more detail. Fishing pressure had a significant negative effect on densities of benthic invertebrates at some grounds; however this study showed that many of the heavily fished sites were composed of dredge-tolerant species. Significant relationships were found between the densities of Asterias rubens and Porania pulvillus and several environmental variables on the south-west fishing grounds, suggesting that environmental variation, rather than fishing pressure was responsible for variations in these species. Further evidence was found of the negative impact of scallop dredging from the long-term analysis of a closed area, implemented in 1989. Recovery of P. maximus has occurred within this closure, without the concurrent increase in of the predatory starfish A.rubens. Relationships between several benthic species with the closed area and environmental variables were found. However, the results of this study indicate a complex ecosystem, which is also affected by predator-prey interactions. The overall findings of this research indicate that closed area management is a relatively straightforward and effective measure in this region. Future management decisions will however, have to account for the potential effects of climate change

The occurrence of cadmium in seawater and in marine organisms and sediments

Methods have been developed for determining cadmium in seawater, marine organisms, and marine sediments. The procedure, based on the dithizone extraction method of Saltzman, is capable of detecting less than 10 mµg of the element and can be used for determining cadmium in silicate rocks; only thallium interferes. To confirm the presence of cadmium and to ensure freedom from contamination, the dithizone extracts were examined spectrographically

with Comments on Feeding Biology

www.mapress.com/zootaxa

CE16004

The first annual Irish Beam trawl Ecosystem (IBES) took place from 6-16th March 2016 on RV Celtic Explorer in the western Celtic sea. The main objective of the survey is to connect the Irish Anglerfish and Megrim Survey (IAMS) to the UK beam trawl surveys in the Celtic Sea, English Channel and Irish Sea, with the purpose of providing a swept-area biomass estimate for anglerfish (Lophius piscatorius and L. budegassa) in area VII. Secondary objectives are to collect data on the distribution and relative abundance of commercially exploited species as well as invertebrates and by-catch species, particularly vulnerable and indicator species. The survey also collects maturity and other biological information for commercial fish species in the western Celtic Sea. The IBES survey is coordinated with the CEFAS Q1 South-west Ecosystem Survey (Q1SWECOS) and uses the same gear and methods

EMFF Offshore Reef Survey, Sensitive Ecosystem Assessment and ROV Exploration of Reef - SeaRover 2018 Cruise Report

This report presents preliminary findings of a 2018 offshore reef survey of Ireland’s Northwest continental margin and Rockall Bank. The survey is part of an extensive three year project, beginning 2017, that is coordinated and led by Ireland’s Marine Institute and INFOMAR (Integrated Mapping for the Sustainable Development of Ireland’s Marine Resources) and funded by the European Maritime and Fisheries Fund (EMFF) Marine Biodiversity Scheme and the National Parks and Wildlife Service (NPWS). The objectives of the project are to implement the EMFF’s Marine Biodiversity Scheme - Natura Fisheries by mapping offshore reef habitats with a view to protecting them from deterioration due to fishing pressures. The reef project aligns with sub-article 6.2 of the Habitats Directive (EC 92/43/EEC) which requires member states to take measures to avoid deterioration of protected habitats. The overarching aim is to quantify the abundance and distribution of offshore biogenic and geogenic reef habitat in Irish waters to fulfil Ireland’s legal mandate and to generate baseline data from which appropriate monitoring of Reef habitat within Special Areas of Conservation (SAC) can be established. The initial survey in July 2017 (O’Sullivan et al. 2017) primarily focussed on the Continental margin west and northwest of Ireland. The second survey leg took place in July 2018 aboard the ILV Granuaile. The survey vessel was equipped with the Marine Institute’s remotely operated vehicle (ROV) Holland 1 to observe seabed features and biological associations along the northwest continental shelf and the eastern flank of the Rockall Ban