Human-driven impacts on marine habitats: A regional meta-analysis in the Mediterranean Sea

Habitat destruction is one of the main threats to environmental integrity. Assessing the consequences of human impacts is crucial both to predict and prevent structural and functional changes of habitats. However, to date almost all studies on marine threats, from regional to global scales, have been entirely qualitative and generally based on little more than expert opinion. We have developed a meta-analytical approach to quantify overall effects of various stressors on different Mediterranean habitat types and to compare the relative importance of different impacts across a range of habitats. We first qualitatively reviewed and synthesized 366 experiments (either manipulative or correlative) collected in the literature. After a selection procedure, we finally quantitatively meta-analyzed 158 experiments. We showed that fisheries (destructive or not), species invasion, aquaculture, sedimentation increase, water degradation and urbanization have negative effects on Mediterranean habitats and associated species assemblages. We also explored the overlap between the impacts identified as important in the Mediterranean and those identified by experts as being important globally, highlighting the inadequacies of relying on expert opinion alone. Finally, we drew attention to the critical lack of empirical knowledge about marine systems in many areas of the Mediterranean, which impedes the implementation of effective conservation measures. Our study is the first to synthesize experimental analyses on human-driven impacts on marine habitats across such a broad geographic scale.     

The interactive effects of UV-B and insecticide exposure on tadpole survival, growth and development

Because declines within amphibian populations can seldom be attributed to a single cause, it is important to focus on multiple stressors, both natural and anthropogenic. Variables such as UV-B radiation and chemical contamination can interact with one another in ways that might not be predicted from single-factor studies. We exposed southern leopard frog (Rana sphenocephala) tadpoles to the insecticide carbaryl and varying intensities of UV-B radiation in artificial ponds and examined their effects on survival, size at metamorphosis, and the duration of the larval period. Tadpole survival to metamorphosis was positively influenced by UV-B intensity. Tadpoles in ponds exposed to carbaryl contained over three times more algae and yielded larger metamorphs than control ponds. Although previous laboratory studies have indicated carbaryl becomes more toxic in the presence of UV-B, we did not find such an effect, perhaps because of the protection afforded by dissolved organic carbon within the ponds. Our research emphasizes the importance of conducting field studies to more accurately predict what occurs under a natural setting.     

The occurrence of phalaris staggers in sheep

Extract

Typical cases of the “staggers” syndrome associated with Phalaris tuberosa poisoning occurred at Invermay Research Station in October, 1954. It is being recorded because detailed records of pasture management and climatic conditions are available for the period when symptoms were seen, also the pasture composition of the Phalaris plot.     

Physiological responses of largemouth bass to acute temperature and oxygen stressors

Abstract Temperature and oxygen gradients exist in nearly every water body, but anthropogenic activities can subject fish to rapid changes in these important environmental variables. These rapid changes in temperature and oxygen (generally referred to as temperature or oxygen shock) may have sub‐lethal consequences depending upon the magnitude and the fish species. This study quantified physiological changes in largemouth bass, Micropterus salmoides (Lacepède), exposed to two levels of heat and cold shocks and to two levels of hypoxic and hyperoxic shocks. Following a cold shock from 20 °C to 8 °C, plasma cortisol and glucose increased after 1 h and lactate dehydrogenase activity increased after 6 h. Plasma glucose and K⁺ concentrations increased 1 h after a heat shock from 20 °C to 32 °C but not after 6 h. Bass subjected to a hypoxic shock from 8 to 2 mg O₂ L^?1 showed decreased plasma K⁺ and increased plasma glucose and white muscle lactate. No changes in physiological parameters were observed in bass subjected up to 18 mg O₂ L^?1 hyperoxia. Results from this study suggest that largemouth bass can tolerate a wide range of temperature and oxygen shocks, but temperature decreases of 20 to 8 °C and hypoxia as low as 4 mg O₂ L^?1 should be avoided to minimise physiological perturbations.     

The implications for aquaculture practice of epigenomic programming of components of the endocrine system of teleostean embryos: lessons learned from mammalian studies

Epigenetics is the study of changes in gene expression patterns that occur without any modification of the underlying nucleotide sequence of the DNA. Modifications of the so‐called epigenome include complex transient or permanent chemical changes of the DNA or histone proteins resulting in the suppression or enhancement of gene expression, together with an array of post‐translational events that modify the translational products. Epigenomic programming (EP) of the genome is an essential component of embryonic development in animals from the totipotent fertilized egg to the pluripotent stem cells, stem cell differentiation and final tissue and organ formation. Many of these EP processes are influenced transiently and some permanently by environmental influences. In eutherian mammals, environmentally related EP of embryos is linked to permanent changes in the phenotype of the progeny, some of which have been associated with adult onset metabolic disorders. Moreover, because some of the epigenetic remodelling occurs in both the soma and germ line, the resultant phenotypic characteristics (some of which are linked to disease states) may be heritable. Although far less is known about the effects of environmentally linked EP on the ontogeny of fishes, the available information suggests that the EP processes are similar amongst all vertebrates, and there are clear parallels between fish and mammals that are discussed in this paper. Our perspective takes the well‐established findings in mammals and uses them to proactively extrapolate to the as yet under‐recognized implications of EP for fish biology and for fish production in intensive aquaculture.     

Plant Growth Promoting Rhizobacteria

Plant growth promoting rhizobacteria (PGPR) are soil bacteria with some beneficial effects on soil properties, plant growth and the environment. In this article, some of the most important advancements in the field of PGPR and their related properties are presented. Such knowledge can be important for understanding regarding the use of PGPR for different uses such as biological fertilization and alleviation of different stresses on plant growth and the environment.     

The legacy of past disturbance: Chronic angling impairs long-term recovery of marine epibenthic communities from acute date-mussel harvesting

Two major concerns affect the way we perceive impacts: first, no ecosystem can still be considered pristine and second, stressors may interact. Untangling the effects of broad-scale anthropogenic stressors is complicated as appropriate unimpacted areas at relevant scales are usually unavailable for contrast with impacted regions. Although the perfect study design in the traditions of small-scale manipulative experiments may not always be possible, many human impacts and the mechanisms associated with ecosystem responses have been highlighted in literature allowing contrasting predictions on expected patterns to be tested. We applied such an approach to the Marine Protected Area of Bergeggi (Ligurian Sea, NW Mediterranean). Our study aimed at assessing the effects of recreational angling (a presumed chronic stress) on the recovery of epibenthic communities following historical date-mussel harvesting (an extreme disturbance) by making and testing alternative predictions on the structure of epibenthic communities that should be apparent depending on the importance of specific mechanisms. Effects of date-mussel harvesting were still visible 20 years after its cessation, mostly because recovery is hampered by persistent sea-urchin grazing. We hypothesized that fish biomass removal by angling favours high sea urchin abundance. Based on these premises, we assembled information on angling pressure, sea urchin abundance and substratum cover by different trophic guilds to test our predictions. Our study indicates that the interaction between date-mussel harvesting and angling produced a shift, from autotrophic-dominated to consumer-dominated communities as a consequence of cascading trophic effects. Such an outcome implies that chronic recreation fishing pressure is blocking recovery in locations previously impacted by date-mussel harvesting. Testing predictions proved efficient in describing the interaction among stressors when system history is known and represents a valuable approach to provide scientifically sound insight for improved conservation management.     

Expert opinion on the status and stressors of brook trout,Salvelinus fontinalis,in Ontario

Ontario supports a vast fisheries resource with an abundance of lakes, rivers and streams. A landscape approach to management informed by a broad‐scale monitoring programme has been initiated to assess the status of fisheries within lakes. However, not all species are assessed by this programme, and there is no provincial monitoring of species inhabiting rivers and streams. As such, changes in the status of a species such as brook trout, Salvelinus fontinalis (Mitchill), could be entirely missed. Brook trout is a highly valued and sought after species by anglers within the province, but there are concerns the species is declining. Given the paucity of broad, empirical data, the status and trends of brook trout across the province have been based on expert opinion at multiple local scales. In 2016, a online questionnaire was sent to brook trout experts to determine status, stressors, management approaches and assess risks (magnitude and probability) to lake and river/stream populations in different geographic areas of Ontario. A Bayesian network was used to analyse responses and develop a risk assessment based on expert opinion for brook trout at multiple scales within the province.     

Cultivar‐dependent yield reductions in white clover due to simulated grazing and White clover mosaic virus infection are associated with differences in storage reserves and antioxidant metabolism

White clover is considered amongst the most important forage legumes in temperate agricultural systems. It contributes to increased quality of pastures through its ability to fix atmospheric nitrogen, providing high nutritional feed for livestock. White clover is host to the potexvirus White clover mosaic virus (WClMV), which is readily transmitted via animal trampling/grazing and mowing. WClMV infection may strongly impact white clover's performance, affecting its ability to compete with other plants in the pasture. Understanding the extent to which the virus influences white clover's growth and yield may contribute to improve pastoral management by pointing out the importance of stress factors on pasture plant performance and herbage yield. In the current study, the effects of WClMV infection and simulated grazing on white clover's fitness, oxidative damage and the induction of antioxidants were investigated. Two cultivars of white clover, Grasslands Huia and Grasslands Kopu II, were subjected to three harvests. In response to WClMV infection and grazing‐like cutting, white clover experienced oxidative stress as evidenced by the accumulation of lipid peroxides and protein carbonyls. Biomass accumulation, given as fresh weight and dry matter content, was also negatively affected. Both stresses induced an increase in ascorbate and glutathione levels and enhanced the activity of superoxide dismutase, ascorbate peroxidase, glutathione peroxidase, catalase and glutathione reductase. Glutathione S‐transferase activity and the levels of reduced ascorbate and reduced glutathione were not affected by either stress.