Taxonomic sufficiency and the increasing insufficiency of taxonomic expertise

Taxonomic sufficiency (TS) involves the identification of taxa only to a level of taxonomic resolution sufficient to permit the detection of changes in stressed assemblages. Recently, however, TS has been proposed also for conservation issues as a tool to estimate biodiversity over large areas and in poorly known environments. This paper briefly reviews the use of TS in environmental impact studies and the effects of TS on sampling procedures and data analyses. The risk of possible loss of information depending on TS and the studied environment are discussed. Concluding remarks deal with the dangers of loss of taxonomic expertise in marine biological studies and assess critically the proposal of TS as a tool to describe biodiversity at a taxonomic level higher than species.

Coastal fish indicate human-induced changes in the Mediterranean littoral

Coastal fish assemblages were studied to assess two sorts of human impacts in southwestern Apulia (SE Italy, Mediterranean Sea). Fish assemblages were evaluated by visual census along two rocky locations impacted by a sewage outfall discharging nearshore (S) and by date-mussel (Lithophaga lithophaga) fisheries (F), respectively, and at two control locations (Cs). Multivariate analyses showed that fish assemblage structures at S and F differed from those at Cs. Asymmetric ANOVAs indicated that species richness were significantly lower both at S (approximately 27%) and at F (approximately 35%) compared with Cs. Total fish abundance was 5- to 7-fold higher at S than at Cs, while the values recorded at F were comparable to those of Cs. At S, average abundances of planktivorous fish and POM feeders were higher, and those of labrids and sparids of the genus Diplodus were lower, respectively, than at Cs. Labrids of the genus Symphodus and small serranids were significantly less abundant at F than Cs. Data suggested that coastal fish respond to the impact caused by the sewage discharge and provided a framework to assess potential benefits of its future displacement to deeper waters. For the first time, moreover, this study provided suggestive evidence that the habitat destruction caused by the illegal date-mussel fisheries may affect fish assemblages.

The response of the algae Fucus virsoides (Fucales, Ochrophyta) to Roundup® solution exposure: A metabolomics approach

Glyphosate, as a broad-spectrum herbicide, is frequently detected in water and several studies have investigated its effects on several freshwater aquatic organisms. Yet, only few investigations have been performed on marine macroalgae. Here, we studied both the metabolomics responses and the effect on primary production in the endemic brown algae Fucus virsoides exposed to different concentration (0, 0.5, 1.5 and 2.5 mg L-1) of a commercial glyphosate-based herbicide, namely Roundup®. Our results show that Roundup® significantly reduced quantum yield of photosynthesis (Fv/Fm) and caused alteration in the metabolomic profiles of exposed thalli compared to controls. Together with the decrease in the aromatic amino acids (phenylalanine and tyrosine), an increase in shikimate content was detected. The branched-amino acids differently varied according to levels of herbicide exposure, as well as observed for the content of choline, formate, glucose, malonate and fumarate. Our results suggest that marine primary producers could be largely affected by the agricultural land use, this asking for further studies addressing the ecosystem-level effects of glyphosate-based herbicides in coastal waters.

The effects of sewage discharge on shallow hard substrate sessile assemblages

On rocky shores, sewage discharges can modify natural distribution patterns of sessile organisms. The impact of sewage on shallow hard substrate assemblages has been assessed along SW Apulian coast (Ionian Sea, Italy), providing a framework to evaluate the benefits of future sewage displacement to deeper waters. Four locations (three controls and one putatively impacted) were selected and three sites were chosen at each location. Each site was sampled by 10 replicate photographic records. Univariate analyses revealed that the outfall did not affect the spatial distribution of number of taxa, total cover and abundance of some dominant taxa (mostly algae, sponges and bryozoans). The outfall negatively influenced the natural distribution pattern of filamentous green algae, whilst some algae (i.e. Gelidiales and Colpomenia sinuosa) were exclusively present at the impacted location. Multivariate analyses revealed that the outfall heavily modified the natural pattern of variability in the structure of the assemblage.

Meiofauna communities, nematode diversity and C degradation rates in seagrass (Posidonia oceanica L.) and unvegetated sediments invaded by the algae Caulerpa cylindracea (Sonder)

We investigated meiofauna and sedimentary C cycling in seagrass (Posidonia oceanica) and unvegetated sediments invaded and not invaded by the non-indigenous tropical algae Caulerpa cylindracea. In both habitats, invaded sediments were characterized by higher organic matter contents. No effect was observed for prokaryotes and C degradation rates. In seagrass sediments, C turnover in invaded beds was about half that in not invaded ones. Meiofaunal communities varied significantly among invaded and not invaded grounds only in bare sediments. In both habitats, nematode species richness and assemblage composition were not affected by the algae. The effect of C. cylindracea on the turnover and nestedness components of the Jaccard dissimilarity varied between the two habitats. We show that the presence of C. cylindracea gives rise to variable consequences on meiofauna biodiversity and C cycling in different habitats. We conclude that further studies across different habitats and ecological components are needed to ultimately understand and predict the consequences of C. cylindracea invasion in shallow Mediterranean ecosystems.

Structural and functional response of meiofauna rocky assemblages to sewage pollution

Despite meiofauna being one of the most popular tool for detecting the ecological effects of different sources of impact, the application of structured experimental designs to this benthic component is typically neglected, especially in subtidal rocky shores. In this study, an asymmetrical design was used to detect hard-bottom meiofaunal abundance and biodiversity response to sewage discharge. Sampling was carried out at a depth of 3-4 m by SCUBA diving, by means of a modified manual corer. Six replicate cores were collected at three sites (80-100 m apart), at each of three locations (one purportedly impacted [I] and two controls [Cs]). A total of 84,994 specimens were collected. The outfall affected meiofaunal assemblages in terms of taxon richness, by determining a significant reduction of the number of taxa in the disturbed location, and community structure, by causing functional changes in terms of a decrease of the abundance of nematodes and an increase of the hydrozoan component. Nematodes and syllid polychaetes showed significant lower average abundance at I. Multivariate analyses showed that both meiofaunal assemblage and syllids were significantly different at I compared with Cs. The sewage outfall also affected patterns of spatial distribution at the scale of site (100 m apart) and of replicate units (centimetres apart), both in syllids and in nematodes. Our results provide evidence that the selection of multiple controls is crucial to prevent the widespread risk of Type II error, highlighting the need of more accurate experimental designs when dealing with meiofauna.

Impact of offshore gas platforms on the structural and functional biodiversity of nematodes

The Mediterranean Sea hosts hundreds of offshore gas platforms, whose activity represents a potential threat to marine ecosystems. Evidence from several studies indicates that nematodes can be highly sensitive to changes in the environmental quality. Here, we investigated the response of nematode assemblages to the presence of offshore gas platforms (located in the central Mediterranean Sea) in terms of spatial heterogeneity, structural and functional diversity. Since the effect of the investigated offshore platforms on macrofaunal assemblages were previously assessed by Terlizzi et al. (2008), the study provided also the opportunity to compare the response of different benthic compartments to the same impact related to fossil fuel extraction on marine environments. The platforms had a significant impact on nematode assemblages up to 1000 m distance from the structure. The effects were evident in term of: a) more homogeneous spatial distribution of nematode assemblages, b) increased trophic diversity of deposit feeders and c) changes in life strategies with an increase of opportunistic species in sediments closer to the platforms. Such effects seemed to be related to the dimension of the platform structures, rather than to chemical pollution or changes in food availability. These findings suggest that the platforms exert a physical alteration of the surrounding environment that is reflected by altered structural and functional traits of nematode biodiversity. The use of nematodes for monitoring the effects of the platforms only partially matched with the results obtained using macrofauna, providing further insights on potential outcomes on the functional response of marine assemblages to fossil fuel extraction.

Assessing the success of marine ecosystem restoration using meta-analysis

Marine ecosystem restoration success stories are needed to incentivize society and private enterprises to build capacity and stimulate investments. Yet, we still must demonstrate that restoration efforts can effectively contribute to achieving the targets set by the UN Decade on Ecosystem Restoration. Here, we conduct a meta-analysis on 764 active restoration interventions across a wide range of marine habitats worldwide. We show that marine ecosystem restorations have an average success of ~64% and that they are: viable for a large variety of marine habitats, including deep-sea ecosystems; highly successful for saltmarshes, tropical coral reefs and habitat-forming species such as animal forests; successful at all spatial scales, so that restoration over large spatial scales can be done using multiple interventions at small-spatial scales that better represent the natural variability, and scalable through dedicated policies, regulations, and financing instruments. Restoration interventions were surprisingly effective even in areas where human impacts persisted, demonstrating that successful restorations can be initiated before all stressors have been removed. These results demonstrate the immediate feasibility of a global 'blue restoration' plan even for deep-sea ecosystems, enabled by increasing availability of new and cost-effective technologies.