Assessment of the potential impacts of coasteering on rocky intertidal habitats in Wales

The relatively new recreational pursuit of coasteering, which has developed in the St David's area of Pembrokeshire, appears to be expanding rapidly. The majority of local commercial recreation providers (outdoor pursuit centers etc.) now appear to offer this pursuit. The majority of the rocky coastlines where it takes place lie within Pembrokeshire Marine Special Area of Conservation (SAC), and are also Sites of Special Scientific Interest (SSSI). No assessment has yet been undertaken of coasteering's potential impact on the intertidal habitats. Therefore the Countryside Council for Wales (CCW) commissioned the Marine Life Information Network (MarLIN) to undertake a desk study of the likely environmental effects of coasteering on rocky intertidal habitats within the Pembrokeshire marine SAC. The desk study was based on a review of the available literature, and in particular the effects of trampling on rocky intertidal communities. Communities (as biotopes) within the Pembrokeshire marine SAC likely to be exposed to coasteering activities were identified from Phase I biotope data for the area, provided by CCW. Where possible, existing research by MarLIN into the intolerance, recoverability and sensitivity of the biotopes identified, was used to identify their potential vulnerability to trampling. The literature review revealed that: - foliose canopy forming algae (e.g. fucoids) were particularly intolerant and sensitive to trampling impacts; - trampling damaged erect coralline turfs, barnacles, and resulted in an increase in bare space; in some cases paths across the shore were visible; - on brown algae dominated shores, understorey algae could suffer due to increased desiccation but algal turf species, opportunists and gastropod grazers (e.g. limpets) could increase in abundance as an indirect effect of trampling, and that - trampling impacts resulted from physical contact and wear and were dependant on the intensity, duration, and frequency of trampling, and even the type of footwear used. A total of 19 intolerant rocky intertidal biotopes were identified as potentially vulnerable to trampling and hence coasteering within the Pembrokeshire marine SAC, of which six are of Welsh importance and eight are nationally rare or scarce. Trampling is a highly localized impact and it was not possible to identify biotopes, and hence communities, actually impacted by coasteering activities in the Pembrokeshire marine SAC. In addition, the majority of the literature addresses the impacts of trampling on wave sheltered or moderately exposed brown algal dominated shores, while coasteering occurs on more wave exposed, steeply inclined shores. Therefore, direct survey of the routes used by coasteering groups within the Pembrokeshire marine SAC is required to identify the intensity, duration and frequency of trampling impact, together with the communities impacted. Given the paucity of data concerning trampling effects in the rocky intertidal in the UK, a survey of the impacts of coasteering would provide an opportunity to examine the effects of trampling and visitor use in steep rocky, wave exposed shores. The report recognizes the potential to engage coasteerers in contributing to the development of strategies for minimizing adverse impacts, recording impacts and collecting information of use in identifying climate change and the occurrence of non-native species.

Impact of climate change on marine pelagic phenology and trophic mismatch

Phenology, the study of annually recurring life cycle events such as the timing of migrations and flowering, can provide particularly sensitive indicators of climate change. Changes in phenology may be important to ecosystem function because the level of response to climate change may vary across functional groups and multiple trophic levels. The decoupling of phenological relationships will have important ramifications for trophic interactions, altering food-web structures and leading to eventual ecosystem-level changes. Temperate marine environments may be particularly vulnerable to these changes because the recruitment success of higher trophic levels is highly dependent on synchronization with pulsed planktonic production. Using long-term data of 66 plankton taxa during the period from 1958 to 2002, we investigated whether climate warming signals are emergent across all trophic levels and functional groups within an ecological community. Here we show that not only is the marine pelagic community responding to climate changes, but also that the level of response differs throughout the community and the seasonal cycle, leading to a mismatch between trophic levels and functional groups.

Understanding the Mechanisms of Cell and Population Responses of Coccolithophores to Changing Ocean Chemistry

The calcifying coccolithophores have been proposed as a potentially vulnerable group in the face of increasing surface ocean CO2 levels. A full understanding of the likely responses of this group requires better mechanistic information on pH- and CO2-sensitive processes that underlie cell function at molecular, cellular and population levels. New findings on the mechanisms of pH homeostasis at a molecular and cellular level in both diatoms and coccolithophores are shaping our understanding of how these important groups may respond or acclimate to changing ocean pH. Critical parameters including intracellular pH homeostasis and cell surface pH will be considered. These studies are being carried out in parallel with genetic studies of natural oceanic populations to assess the natural genetic and physiological diversity that will underlie adaptation of populations in the long term.

Theoretical analysis of ocean color radiances anomalies and implications for phytoplankton groups detection in case 1 waters

Past years have seen the development of different approaches to detect phytoplankton groups from space. One of these methods, the PHYSAT one, is empirically based on reflectance anomalies. Despite observations in good agreement with in situ measurements, the underlying theoretical explanation of the method is still missing and needed by the ocean color community as it prevents improvements of the methods and characterization of uncertainties on the inversed products. In this study, radiative transfer simulations are used in addition to in situ measurements to understand the organization of the signals used in PHYSAT. Sensitivity analyses are performed to assess the impact of the variability of the following three parameters on the reflectance anomalies: specific phytoplankton absorption, colored dissolved organic matter absorption, and particles backscattering. While the later parameter explains the largest part of the anomalies variability, results show that each group is generally associated with a specific bio-optical environment which should be considered to improve methods of phytoplankton groups detection.

Spatial variability of marine climate change impacts in the North Atlantic

There is an accumulating body of evidence to suggest that many marine ecosystems in the North Atlantic, both physically and biologically are responding to changes in regional climate caused predominately by the warming of air and sea surface temperatures (SST) and to a varying degree by the modification of oceanic currents, precipitation regimes and wind patterns. The biological manifestations of rising SST and oceanographic changes have variously taken the form of biogeographical, phenological, physiological and community changes. For example, during the last 40 years there has been a northerly movement of warmer water plankton by 10 degree latitude in the north-east Atlantic and a similar retreat of colder water plankton to the north. This geographical movement is much more pronounced than any documented terrestrial study, presumably due to advective processes playing an important role. Other research has shown that the plankton community in the North Sea has responded to changes in SST by adjusting their seasonality (in some cases a shift in seasonal cycles of over six weeks has been detected), but more importantly the response to climate warming varied between different functional groups and trophic levels, leading to mismatch. Therefore, while it has been documented that marine ecosystems in certain regions of the Atlantic have undergone some conspicuous changes over the last few decades it is not known whether this is a pan-oceanic homogenous response. Using these two most prominent responses and/or indicative signals of pelagic ecosystems to hydro-climatic change, changes in species phenology and the biogeographical movement of populations, we attempt to identify vulnerable regional areas in terms of particularly rapid and marked change.

A new procedure to optimize the selection of groups in a classification tree

Agglomerative cluster analyses encompass many techniques, which have been widely used in various fields of science. In biology, and specifically ecology, datasets are generally highly variable and may contain outliers, which increase the difficulty to identify the number of clusters. Here we present a new criterion to determine statistically the optimal level of partition in a classification tree. The criterion robustness is tested against perturbated data (outliers) using an observation or variable with values randomly generated. The technique, called Random Simulation Test (RST), is tested on (1) the well-known Iris dataset [Fisher, R.A., 1936. The use of multiple measurements in taxonomic problems. Ann. Eugenic. 7, 179–188], (2) simulated data with predetermined numbers of clusters following Milligan and Cooper [Milligan, G.W., Cooper, M.C., 1985. An examination of procedures for determining the number of clusters in a data set. Psychometrika 50, 159–179] and finally (3) is applied on real copepod communities data previously analyzed in Beaugrand et al. [Beaugrand, G., Ibanez, F., Lindley, J.A., Reid, P.C., 2002. Diversity of calanoid copepods in the North Atlantic and adjacent seas: species associations and biogeography. Mar. Ecol. Prog. Ser. 232, 179–195]. The technique is compared to several standard techniques. RST performed generally better than existing algorithms on simulated data and proved to be especially efficient with highly variable datasets.

Light enhanced amino acid uptake by dominant bacterioplankton groups in surface waters of the Atlantic Ocean

35S-Methionine and 3H-leucine bioassay tracer experiments were conducted on two meridional transatlantic cruises to assess whether dominant planktonic microorganisms use visible sunlight to enhance uptake of these organic molecules at ambient concentrations. The two numerically dominant groups of oceanic bacterioplankton were Prochlorococcus cyanobacteria and bacteria with low nucleic acid (LNA) content, comprising 60% SAR11-related cells. The results of flow cytometric sorting of labelled bacterioplankton cells showed that when incubated in the light, Prochlorococcus and LNA bacteria increased their uptake of amino acids on average by 50% and 23%, respectively, compared with those incubated in the dark. Amino acid uptake of Synechococcus cyanobacteria was also enhanced by visible light, but bacteria with high nucleic acid content showed no light stimulation. Additionally, differential uptake of the two amino acids by the Prochlorococcus and LNA cells was observed. The populations of these two types of cells on average completely accounted for the determined 22% light enhancement of amino acid uptake by the total bacterioplankton community, suggesting a plausible way of harnessing light energy for selectively transporting scarce nutrients that could explain the numerical dominance of these groups in situ.

Interactions between multiple large macrofauna species and nematode communities — Mechanisms for indirect impacts of trawling disturbance

Highlights •We exposed meiofauna to 7 different large macrofauna species at high and low densities. •Macrofauna presence altered nematode community structure and reduced their abundance. •Macrofauna species had similar effects by reducing the few dominant nematode species. •Meio–macrofauna resource competition and spatial segregation are the main drivers. •Trawling effects on macrofauna affect nematode communities indirectly. Diverse assemblages of infauna in sediments provide important physical and biogeochemical services, but are under increasing pressure by anthropogenic activities, such as benthic trawling. It is known that trawling disturbance has a substantial effect on the larger benthic fauna, with reductions in density and diversity, and changes in community structure, benthic biomass, production, and bioturbation and biogeochemical processes. Largely unknown, however, are the mechanisms by which the trawling impacts on the large benthic macro- and megafauna may influence the smaller meiofauna. To investigate this, a mesocosm experiment was conducted whereby benthic nematode communities from a non-trawled area were exposed to three different densities (absent, low, normal) of 7 large (> 10 mm) naturally co-occurring, bioturbating species which are potentially vulnerable to trawling disturbance. The results showed that total abundances of nematodes were lower if these large macrofauna species were present, but no clear nematode abundance effects could be assigned to the macrofauna density differences. Nematode community structure changed in response to macrofauna presence and density, mainly as a result of the reduced abundance of a few dominant nematode species. Any detectable effects seemed similar for nearly all macrofauna species treatments, supporting the idea that there may be a general indirect, macrofauna-mediated trawling impact on nematode communities. Explanations for these results may be, firstly, competition for food resources, resulting in spatial segregation of the meio- and macrobenthic components. Secondly, different densities of large macrofauna organisms may affect the nematode community structure through different intensities of bioturbatory disturbance or resource competition. These results suggest that removal or reduced densities of larger macrofauna species as a result of trawling disturbance may lead to increased nematode abundance and hints at the validity of interference competition between large macrofauna organisms and the smaller meiofauna, and the energy equivalence hypothesis, where a trade-off is observed between groups of organisms that are dependent on a common source of energy.

Indications of a climate effect on Mediterranean fisheries

Using the Food and Agriculture Organization’s (FAO) Mediterranean capture fisheries production dataset in conjunction with global and Mediterranean sea surface temperatures, we investigated trends in fisheries landings and landings per unit of effort of commercially important marine organisms, in relation to temperature oscillations. In addition to the overall warming trend, a temperature shift was detected in the Mediterranean Sea in the late 1990s. Fisheries landings fluctuations were examined for the most abundant commercial species (59 species) and showed significant year-to-year correlations with temperature for nearly 60 % of the cases. From these, the majority (~70 %) were negatively related and showed a reduction of 44 % on average. Increasing trends were found, mainly in the landings of species with short life spans, which seem to have benefited from the increase in water temperature. Τhe effect of oceanic warming is apparent in most species or groups of species sharing ecological (e.g. small and medium pelagic, demersal fish) or taxonomic (e.g. cephalopods, crustaceans) traits. A landings-per-unit-of-effort (LPUE) proxy, using data from the seven Mediterranean European Union member states, also showed significant correlation with temperature fluctuations for six out of the eight species examined, indicating the persistence of temperature influence on landings when the fishing effect is accounted for. The speed of response of marine landings to the warming of the Mediterranean Sea possibly shows both the sensitivity and the vulnerable state of the fish stocks and indicates that climate should be examined together with fisheries as a factor shaping stock fluctuations.