Aquatic Conservation: Marine and Freshwater Ecosystems

The merits of effective communication capable of motivating behavioural change, policy action and support for marine conservation are often emphasized. To date, however, environmental communication, as a field, has largely focused on terrestrial ecosystems and more recently on climate change, leaving research‐informed marine conservation communication neglected.

Adding to the small compilation of marine conservation communication literature, this integrative review provides a new understanding of how six message frames (emotional, problem/solution, outcome, value‐based, distance, and social norm) can interactively help enhance the effectuality of conservation messages. Insights from the framing‐related literature are merged with those from relevant fields including the theoretical literature, and the behavioural, social, and environmental sciences to define concepts, provide examples and explain the relevance of the six identified frames. The potential strength of these frames are discussed and suggestions on how they might be used to communicate different marine conservation issues are provided.

In order to assess the susceptibility of marine habitats to biological invasions, a dataset was gathered of the occurrence of 3899 species from 29 phyla, taken from 93 marine sites located along the Italian coast in the period 2000–2012.

In total, 61 AS belonging to 11 phyla have been recorded. Invertebrates were the most represented (63%). Alien species were found in all the habitats examined (EUNIS, level 2), although they showed highest abundance in benthic habitats. Most of the AS were associated with a single EUNIS habitat, while some of them were present in more than one habitat. Trans‐habitat occurrence suggests the potential invasiveness of AS.

According to statistical analysis, AS recorded could have been more numerous, since some of the marine habitats seemed to be still unsaturated. The model that best describes the spread of AS takes account of both native species richness (Rn) and EUNIS habitat type as explanatory variables. The number of observed AS was directly related to Rn and it was highest in rocky circalittoral and infralittoral habitats.

The results of this macro‐ecological study focus on the importance of performing large‐scale studies, since adopting ecosystem approaches to marine invasion management seems especially fruitful.

The results, moreover, highlight the importance of AS monitoring of different habitats, from those subjected to anthropogenic pressure, historically considered to be hubs of introduction of AS, to the most biologically rich and diverse marine habitats. Indeed, it is necessary to set monitoring strategies to detect the introduction, the distribution and persistence of AS over time. These recommendations are especially significant in the light of the strategic plans currently under formulation in Mediterranean countries with regard to AS monitoring.

The facilitative effect of the beaver Castor canadensis on a waterbird community of seven species of waders and ducks in boreal ponds was studied by using the before–after control–impact method (BACI) and analysing the effect of the duration of flooding. The before–after setting could be used since beavers had caused disturbance by flooding several forest ponds during the course of this long‐term study (1988–2009). The study took place in southern Finland, where waterbirds were surveyed four times during the breeding season.

The number of waterbird species per pond per year was significantly higher during beaver inundation than before beaver activity, as was the waterbird abundance per survey. Changes were negligible in the controls. The numbers of all seven species increased during flooding, although the increase was significant in only three species. Common teal Anas crecca and green sandpiper Tringa ochropus showed the most positive numerical response to flooding. Mallard Anas platyrhynchos and wigeon Anas penelope were new species entering the duck guild in the flooded wetlands. The beneficial effect of the flood lasted the whole period of inundation, although the most substantial increase in species number appeared during the first two years of flooding.

The beaver acted as a whole‐community facilitator for waterbirds. It was inferred from previous studies that this was done by modifying the habitat to make it more productive and structurally favourable. It is concluded that favouring beavers is a worthwhile tool in restoring wetlands to promote waterbird communities.

Despite growing interest in reintroduction programmes, surprisingly little is known about the ecology of beaver in dryland streams, and science to guide management decisions is often fragmented and incomplete.

This paper reviews the literature addressing the ecological effects and management of beaver activity in drylands of North America, highlighting conservation implications, distinctions between temperate and dryland streams, and knowledge gaps.

Well‐documented effects of beaver activity in drylands include changes to channel morphology and groundwater processes, creation of perennial wetland habitat, and substantial impacts to riparian vegetation. However, many hypothesized effects derived from temperate streams lack empirical evidence from dryland streams.

Topics urgently in need of further study include the distribution and local density of beaver dams; consequences of beaver dams for hydrology and water budgets; and effects of beaver activity on the spread of aquatic and riparian non‐native species.

In summary, this review suggests that beaver activity can create substantial benefits and costs for conservation. Where active beaver introductions or removals are proposed, managers and conservation organizations are urged to implement monitoring programmes and consider the full range of possible ecological effects and trade‐offs.

This paper presents data on two years of willow (Salix spp.) and aspen (Populus tremula L.) regrowth following tree felling by captive beavers within two large semi‐natural enclosures in eastern Scotland. Both willow and aspen are highly preferred by beavers.

Regrowth of willow stems was quantified from cut stumps, felled logs and partially severed (‘incompletely felled’) trees, and compared with growth of stems in the canopies of untouched willows.

Maximum annual regrowth was observed in incompletely felled trees, followed by cut stumps and then unfelled control trees. Mean regrowth rates were ca 18 m regrowth per metre of measured tree section per year in incompletely felled trees. This was approximately 12 times more annual regrowth than that observed in unfelled trees, despite apparently selective browsing of the regrowth of incompletely felled trees by roe deer.

Although incompletely felled willows represent a relatively small component of felling activity (9% of all felled willow), they contribute disproportionately to the biomass of beaver‐engineered riparian woodlands, creating a more multi‐layered habitat structure.

Willow regrowth in inundated areas was avoided by deer, and harvesting of regrowth by beavers was rare.

Significant regrowth from 11 stumps of aspen in 2 years post‐felling occurred by suckering, with 85 suckers of mean height 2.1 m being recorded, all of which were subsequently avoided by browsing deer and beavers.

These data suggest that rapid regeneration of willow and aspen will occur in riparian woodlands in the event of major felling activity by Eurasian beaver, even in the presence of low to moderate levels of roe deer browsing, and that the conservation status of both these trees or the wider habitats that they form would not be threatened by a well planned and managed reintroduction of beavers to Scotland.

This study assesses bycatch rates of bottom and drift gillnets operating in southern Brazil, and describes the sex and age classes of individuals captured.

In 80 bottom gillnet sets, 33 penguins were captured (85% adults), 14 were sexed of which 13 were females. In 41 drift gillnet sets, four penguins were captured, three of which were juveniles.

The mean bycatch rates, measured as number of penguins km⁻² of net and number of penguins km⁻² h⁻¹, were significantly higher for the drift gillnets.

Despite the lower bycatch rates, owing to the higher fishing effort in terms of number of boats, net length, net area, soak time and fishing season, the magnitude of penguin bycatch in the bottom gillnet fishery cannot be ignored.

Despite based on small sample size, the predominance of adult and female Magellanic penguins as bycatch in gillnet fisheries in southern Brazil agrees with previous studies suggesting that females displace further north than males. In addition, such evidence contributes to the male‐biased sex ratio in breeding grounds, and the long‐term decline of major Patagonian colonies owing to higher female mortality during winter.