Marine litter in the Nordic Seas: Distribution composition and abundance

Litter has been found in all marine environments and is accumulating in seabirds and mammals in the Nordic Seas. These ecosystems are under pressure from climatic change and fisheries while the human population is small. The marine landscapes in the area range from shallow fishing banks to deep-sea canyons. We present density, distribution and composition of litter from the first large-scale mapping of sea bed litter in arctic and subarctic waters. Litter was registered from 1778 video transects, of which 27% contained litter. The background density of litter in the Barents Sea and Norwegian Sea is 202 and 279 items/km2 respectively, and highest densities were found close to coast and in canyons. Most of the litter originated from the fishing industry and plastic was the second most common litter. Background levels were comparable to European records and areas with most littering had higher densities than in Europe.publishedVersio

Cold Temperate Coral Habitats

Cold-water coral habitats are constituted by a great variety of anthozoan taxa, with reefs and gardens being homes for numerous invertebrates and fish species. In the cold temperate North Atlantic, some coral habitats such as Lophelia pertusa reefs, and Primnoa/Paragorgia dominated coral gardens occur on both sides of the Atlantic over a wide latitudinal range. Other habitats, as some dominated by species of Isididae and Chrysogorgidae seem to have a more local/regional distribution. In this chapter, we describe the habitat characteristics of cold-water coral reefs, soft and hard-bottom coral gardens, and sea pen meadows with their rich associated fauna illustrated with numerous photos

Distribution and suitable habitat of the cold-water corals Lophelia pertusa, Paragorgia arborea, and Primnoa resedaeformis on the Norwegian continental shelf

Cold-water corals are habitat-forming species that are also classified as indicators of vulnerable marine ecosystems (VMEs) due to the threat of various anthropogenic impacts, e.g., fisheries and oil/mineral exploration. To best protect VMEs, knowledge of their habitat requirements and distribution is essential. However, comprehensive sampling of the deep sea is difficult due to access and cost constraints, so species distribution modeling (SDM) is often used to predict overall distributions and ecological preferences of species based on limited data. We used Maximum Entropy (Maxent) modeling to predict the probability of presence of the reef-building scleractinian Lophelia pertusa and the octocorals Paragorgia arborea and Primnoa resedaeformis using a total of 2149 coral presence points and 15 environmental predictor variables. The environmental variables used in the analysis were processed to 176 m resolution and included bathymetry, depth, geomorphometric characteristics [slope, aspect, and bathymetric position index (BPI)], oceanography (temperature, salinity, current directions, and speed), surface chlorophyll a concentration, sediment type, and marine landscape type. Comparing presence points with environmental data showed that the temperature and depth range for Lophelia was narrower compared to the gorgonians, and it occurred in shallower, warmer water. Observations showed that Lophelia had a broad, bimodal response to Broad BPI, while the predicted model indicated a more narrow response. Paragorgia tolerated the greatest range of sloping according to the model. All three species were observed with a bimodal pattern along a wide range of mean current speed, while the models indicated a high response to faster current speed. Jackknife tests showed that sediment type was an important predictor for gorgonian corals, while BPI and minimum temperature were more important for Lophelia. The spatial precision of the models could be further increased by applying environmental layers with a higher and uniform spatial resolution. The predicted distribution of corals and their relation to environmental variables provides an important background for prioritizing areas for detailed mapping surveys and will aid in the conservation efforts for these VMEs in Norwegian waters and beyond.publishedVersio

First description of a Lophelia pertusa reef complex in Atlantic Canada

For the first time, we describe a cold-water coral reef complex in Atlantic Canada, discovered at the shelf break, in the mouth of the Laurentian Channel. The study is based on underwater video and sidescan sonar. The reef complex covered an area of approximately 490×1300 m, at 280–400 m depth. It consisted of several small mounds (< 3 m high) where the scleractinian Lophelia pertusa occurred as live colonies, dead blocks and skeletal rubble. On the mounds, a total of 67 live colonies occurred within 14 patches at 300–320 m depth. Most of these (67%) were small (< 20 cm high). Dead coral (rubble and blocks), dominated (88% of all coral observations). Extensive signs of damage by bottom-fishing gear were observed: broken and tilted coral colonies, over-turned boulders and lost fishing gear. Fisheries observer data indicated that the reef complex was subjected to heavy otter trawling annually between 1980 and 2000. In June 2004, a 15 km2 conservation area excluding all bottom-fishing was established. Current bottom fisheries outside the closure include otter trawling for redfish and anchored longlines for halibut. Vessel monitoring system data indicate that the closure is generally respected by the fishing industry.publishedVersio

Predicting the Distribution of Indicator Taxa of Vulnerable Marine Ecosystems in the Arctic and Sub-arctic Waters of the Nordic Seas

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Discerning the Management-Relevant Ecology and Distribution of Sea Pens (Cnidaria: Pennatulacea) in Norway and Beyond

Sea pens are considered to be of conservation relevance according to multiple international legislations and agreements. Consequently, any information about their ecology and distribution should be of use to management decision makers. This study aims to provide such information about six taxa of sea pen in Norwegian waters [Funiculina quadrangularis (Pallas, 1766), Halipteris spp., Kophobelemnon stelliferum (Müller, 1776), Pennatulidae spp., Umbellula spp., and Virgulariidae spp.]. Data exploration techniques and ensembled species distribution modelling (SDM) are applied to video observations obtained by the MAREANO project between 2006 and 2020. Norway-based ecological profiles and predicted distributions are provided and discussed. External validations and uncertainty metrics highlight model weaknesses (overfitting, limited training/external observations) and consistencies relevant to marine management. Comparison to international literature further identifies globally relevant findings: (a) disparities in the environmental profile of F. quadrangularis suggest differing “realised niches” in different locations, potentially highlighting this taxon as particularly vulnerable to impact, (b) none of the six sea pen taxa were found to consistently co-occur, instead partially overlapping environmental profiles suggests that grouping taxa as “sea pens and burrowing megafauna” should be done with caution post-analyses only, (c) higher taxonomic level groupings, while sometimes necessary due to identification issues, result in poorer quality predictive models and may mask the occurrence of rarer species. Community-based groupings are therefore preferable due to confirmed shared ecological niches while greater value should be placed on accurate species ID to support management efforts.publishedVersio

Modeling the Distribution of Habitat-Forming, Deep-Sea Sponges in the Barents Sea: The Value of Data

The use of species occurrence as a proxy for habitat type is widespread, probably because it allows the use of species distribution modeling (SDM) to cost-effectively map the distribution of e.g., vulnerable marine ecosystems. We have modeled the distribution of epibenthic megafaunal taxa typical of soft-bottom, Deep-Sea Sponge Aggregations (DSSAs), i.e., “indicators,” to discover where in the Barents Sea region this habitat is likely to occur. The following taxa were collectively modeled: Hexadella cf. dedritifera, Geodia spp., Steletta sp., Stryphnus sp. The data were extracted from MarVid, the video database for the Marine AREAl database for NOrwegian waters (MAREANO). We ask whether modeling density data may be more beneficial than presence/absence data, and whether using this list of indicator species is enough to locate the target habitat. We use conditional inference forests to make predictions of probability of presence of any of the target sponges, and total density of all target sponges, for an area covering a large portion of the Norwegian Barents Sea and well beyond the data’s spatial range. The density models explain 0.88), depending on the variables/samples used to train the model. The predicted surfaces were then classified on the basis of a probability threshold (0.75) and a density threshold (13 n/100 m2) to obtain polygons of “core area” and “hotspots” respectively (zones). The DSSA core area comprises two main regions: the Egga shelf break/Tromsøflaket area, and the shelf break southwest of Røst bank in the Træna trench. Four hotspots are detected within this core area. Zones are evaluated in the light of whole-community data which have been summarized as taxon richness and density of all megafauna. Total megafaunal density was significantly higher inside the hotspots relative to the background. Richness was not different between zones. Hotspots appeared different to one another in their richness and species composition although no tests were possible. We make the case that the effectiveness of the indicator species approach for conservation planning rests on the availability of density data on the target species, and data on co-occurring species.publishedVersio

Editorial : Seafloor mapping of the Atlantic Ocean

Patricio Bernal, the Coordinator of the International Union for Conservation of Nature High Seas Initiative, once wrote: “We know more about the surface of the Moon and about Mars than we do about the deep seafloor, despite the fact that we have yet to extract a gram of food, a breath of oxygen or a drop of water from those bodies” (Snelgrove, 2010). Often referred to as the last frontier on Earth, the deep seafloor is thought to shelter both critical ecosystems and exploitable resources (i.e., minerals, bio-active natural products, and genetic material, in addition to food resources already being harvested by the fishing industry). These resources are said to have enormous potential to contribute to the growth of the blue economy, potential that will be realized only with an increased understanding of deep-sea environments (Glover et al., 2018). However, knowledge of deep-sea environments and the anthropogenic impacts on them lags in comparison to other marine environments. To address this issue, several cooperative international agreements have been signed. For instance, the Galway Statement (signed by the European Union, United States, and Canada) and the Belém Statement (also signed by Brazil and South Africa) were endorsed to launch an All-Atlantic Ocean Research Alliance. This alliance aims to increase our understanding of the Atlantic Ocean and its systems and promote the sustainable management of its resources. In addition, activities and programs associated with the United Nations Decade of Ocean Science for Sustainable Development (2021–2030), such as The Nippon Foundation-GEBCO Seabed 2030 Project, Challenger 150, and the One Ocean Network for Deep Observation, will likely help increase awareness of the importance of seafloor mapping

A data science approach for multi-sensor marine observatory data monitoring cold water corals (Paragorgia arborea) in two campaigns

Fixed underwater observatories (FUO), equipped with digital cameras and other sensors, become more commonly used to record different kinds of time series data for marine habitat monitoring. With increasing numbers of campaigns, numbers of sensors and campaign time, the volume and heterogeneity of the data, ranging from simple temperature time series to series of HD images or video call for new data science approaches to analyze the data. While some works have been published on the analysis of data from one campaign, we address the problem of analyzing time series data from two consecutive monitoring campaigns (starting late 2017 and late 2018) in the same habitat. While the data from campaigns in two separate years provide an interesting basis for marine biology research, it also presents new data science challenges, like the the marine image analysis in data form more than one campaign. In this paper, we analyze the polyp activity of two Paragorgia arborea cold water coral (CWC) colonies using FUO data collected from November 2017 to June 2018 and from December 2018 to April 2019. We successfully apply convolutional neural networks (CNN) for the segmentation and classification of the coral and the polyp activities. The result polyp activity data alone showed interesting temporal patterns with differences and similarities between the two time periods. A one month “sleeping” period in spring with almost no activity was observed in both coral colonies, but with a shift of approximately one month. A time series prediction experiment allowed us to predict the polyp activity from the non-image sensor data using recurrent neural networks (RNN). The results pave a way to a new multi-sensor monitoring strategy for Paragorgia arborea behaviour.publishedVersio

Vurdering av norske korallrev

In 1999, the Norwegian fisheries authorities established a regulation for the protection of cold-water coral reefs, Lophelia pertusa, against damage from bottom trawling, including: prohibition of intentional destruction, precaution when fishing in the vicinity of known sites and, for certain locations, a total ban of bottom trawling. As of today, there are nine areas that have received a species protection and where bottom trawling is banned: Sula, Iverryggen, Røst, Tisler, Fjellknausene, Korallen, Træna, Breisunddjupet and Rauerfjorden (for geographical coordinates see Appendix 2). The present report is a response to a request from the Directorate of Fisheries to “evaluate areas for protection of coral reefs”. The request included three tasks: 1) Describe the distribution of reefs near by the protected sites on the background of new knowledge. The directorate will use the information to consider whether or not the present borders of the protected areas are appropriate. 2) Evaluate whether the nine specific sites are representative for the reefs along the coast and offshore. 3) Consider whether new sites can add to the total representativeness of protected reefs along the coast and offshore. In this report the representativity of larger known Lophelia sites has been evaluated based on a combination of growth form and geographical location. The aim was to create a network of protected coral areas that covers most of the different reef forms in each to four defined sub-coral provinces and seascapes along the Norwegian coastline. The reef forms are (example site): 1) elongated or cigar-like (Træna), 2) drop-like to elongated, with or without signs of sea-bed erosion at the reef front facing the current (Breisunddjupet, Hola), 3) reef-complexes consisting of hundreds or thousands of coral domes growing close to each other or merged together (Sula), 4) single and circular of up to 50 m in height (Fugløya), 5) wall-reefs consist of colonies growing on steep walls or on overhangs in fjords (Straumsneset), 6) hillreefs grow in sloping terrain on the coast and in fjords, for example on sills of fjords (Stjernsund). A last category (7) refers to their function: connectivity or bridgehead that function as links between reefs in the Atlantic ocean and the Norwegian coast through the transport of larvae (Storneset). In addition we divided the Norwegian sea areas into three seascapes: 1) coast and the fjords, 2) continental shelf, 3) shelf brake including the slope. The Norwegian coast boarders three seas: the North Sea with Skagerrak, the Norwegian Sea and the Barents Sea. Although these regions are all influenced by the North-East Atlantic water, they have distinctive physical conditions that will, for instance, influence the connectivity between Lophelia in Norwegian waters and the reefs further south-west in the Atlantic ocean. Our hypothesis is that higher exposure of an area to the inflow of Atlantic water, the higher the connectivity among reefs in the Atlantic Ocean and Norwegian waters. This hypothesis and the general hydrographical situation are the basis for an identification of four Coral Subprovinces along the Norwegian coast and shelf: Skagerrak, Vestlandet, Midt-Norge and Nord-Norge. Within these sub-provinces, we suggest new sites that will add to the representativeness of protected reefs. We also suggest to close at least one site in each of the Coral Sub-provinces, against all fishing activities including long-line and gill-net fishing. Once the fishing impact is removed, it will allow the study of other impact factors, such as climate change and ocean acidification, which in turn will make it easier to interpret the results of reef monitoring in the future