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Marine algae offer numerous extrinsic and intrinsic ecosystem services. Human impacts and climate change, however, have contributed to disrupting or compromising their ecology and distribution. Continuing research and monitoring of marine algae are pivotal but require public support. This study investigated public knowledge of and attitude towards marine algae and support for their research and monitoring. The focus was coastal users, a diversified group of interest for research into the perceptions of marine algae. The study was carried out in the Conero Riviera (Adriatic Sea, Italy), a location where coastal users come into contact with several types of marine algae. Semi-structured interviews were conducted in 2020 with 202 randomly selected scuba divers, beach and promenade visitors in the Riviera. Data analysis was thematic and statistical. Participants possessed basic knowledge of marine algae, which was more sophisticated among scuba divers. Coastal users ascribed both extrinsic and intrinsic values to marine algae. Most participants recognised the importance of protecting and managing marine algae while supported research and monitoring, prioritising types of marine algae which provide specific extrinsic and intrinsic ecosystem services. Based on the results, strategies of outreach, communication and engagement are suggested for the study location and types of coastal users. This study contributed to the growing body of research on Ocean Literacy, confirming the importance of investigating perceptions of marine resources to steer research, management and outreach strategies.

Coastal and marine recreational groups have been widely involved in activities of environmental monitoring, also referred to as participatory or citizen science. There are, however, several factors influencing interest and ultimately participation by these groups, ranging from demographic to recreation specialisation, attitudinal and behavioural variables. These need to be considered when designing citizen science projects as well as recruitment and engagement approaches. Kelp forests are cold-water coastal ecosystems holding enormous intrinsic and extrinsic value and are under pressure from local and global stressors. Scientists worldwide have called for increased long-term kelp monitoring efforts to fill data gaps and exploit the ecological indicator properties of kelp to monitor environmental change. They have also called for research focusing on people and raising public awareness to garner support for kelp conservation. Citizen science could be one of many strategies to address these calls, with recreational divers being central contributors to local and international kelp monitoring projects. This study aimed to assess recreational divers’ interest in kelp monitoring, characterising those wishing to contribute based on variables known to influence interest and participation in citizen science, and comparing different geographic regions. A phenomenology approach in qualitative research was used to collect data from 100 kelp divers in South Africa and New Zealand. Thematic analysis, the quantification of qualitative data and statistical analysis were used to describe the sample. All participants were interested in kelp monitoring, providing reasons which were significantly related to specific variables. Previous participation in kelp projects by a proportion of the sample enabled the profiling of those who may ultimately commit to kelp monitoring. Geographic comparisons revealed how kelp divers largely have experiences, knowledge and attitudes regarding kelp and its monitoring in common, while also showing important context-specific differences. The results of this study were used to generate five scenarios of recreational divers’ involvement in kelp citizen science, including field-based monitoring as part of local and international projects, public education, miscellaneous conservation activities, and “opportunistic” kelp monitoring. The data ultimately aim to provide useful information for the planning and development of both local and international kelp monitoring initiatives based on citizen science.

1. Most ecological studies require knowledge of animal abundance, but it can be challenging and destructive of habitat to obtain accurate density estimates for cryptic species, such as crustaceans that tunnel deeply into the seafloor, beaches, or mudflats. Such fossorial species are, however, widely used in environmental impact assessments, requiring sampling techniques that are reliable, efficient, and environmentally benign for these species and environments. 2. Counting and measuring the entrances of burrows made by cryptic species is commonly employed to index population and body sizes of individuals. The fundamental premise is that burrow metrics consistently predict density and size. Here we review the evidence for this premise. We also review criteria for selecting among sampling methods: burrow counts, visual censuses, and physical collections. 3. A simple 1:1 correspondence between the number of holes and population size cannot be assumed. Occupancy rates, indexed by the slope of regression models, vary widely between species and among sites for the same species. Thus, ‘average’ or ‘typical’ occupancy rates should not be extrapolated from site- or species specific field validations and then be used as conversion factors in other situations. 4. Predictions of organism density made from burrow counts often have large uncertainty, being double to half of the predicted mean value. Whether such prediction uncertainty is ‘acceptable’ depends on investigators' judgements regarding the desired detectable effect sizes. 5. Regression models predicting body size from burrow entrance dimensions are more precise, but parameter estimates of most models are specific to species and subject to site-to-site variation within species. 6. These results emphasise the need to undertake thorough field validations of indirect census techniques that include tests of how sensitive predictive models are to changes in habitat conditions or human impacts. In addition, new technologies (e.g. drones, thermal-, acoustic- or chemical sensors) should be used to enhance visual census techniques of burrows and surface-active animals.

The morphodynamic state and habitat properties of microtidal sandy beaches largely account for variations in macrofauna structure. In ecological theory, the habitat harshness hypothesis and the habitat safety hypothesis explain variations in macrofauna populations of the intertidal and supratidal zones of sandy beaches. The former hypothesis states that intertidal macrofauna should increase from reflective to dissipative beaches. The latter hypothesis supports the idea that supratidal species are more successful on reflective beaches, given their relative independence from the swash. However, trends in abundance of supratidal species, particularly crustaceans, have been unclear and further investigation is therefore needed. This study tested the two hypotheses on the largest invertebrate intertidal-to-supratidal crustacean on sandy beaches, namely the ghost crab (genus Ocypode). Variations in ghost crab burrow density, abundance, size and across-shore distribution were measured on four warm-temperate microtidal sandy beaches in KwaZulu-Natal, South Africa. Burrow numbers increased with beach morphodynamic state, while average burrow size decreased. The steepest, narrowest and most inundation-prone beach represented the least hospitable environment for the ghost crabs. The results that are reported here tend to support the habitat harshness hypothesis. However, the relevance of i) individual physical variables, ii) tidal action, and iii) the ecology of various species, in shaping ghost crab population dynamics, is also discussed. The results contribute to the knowledge regarding population dynamics of intertidal and supratidal crustaceans across beach types.

Off-road vehicles (ORVs) are popular in coastal recreation, although they have negative impacts on sandy shores. In South Africa, ORVs are banned from most coastal areas, while some areas are designated for restricted ORV use, providing an opportunity to assess whether ORV traffic restrictions translate into biological returns. In Sodwana Bay, the impact of ORVs on ghost crab populations was investigated. During Easter 2012, ghost crab burrows were counted on beach sections open and closed to traffic. Burrow density in the Impact section was less than a third that of the Reference section, and by the end of the study burrow size in the Impact section was half that of the Reference section. ORV traffic caused a shift in burrow distribution to the Lower beach. However, differences in burrow densities between sections were 14 times smaller than differences obtained at a time when ORV use in Sodwana Bay was not controlled. While confirming the well-established detrimental effects of ORV use on sandy beach ecosystems, results demonstrated that traffic restrictions on beaches measurably minimize impacts to the fauna, thus translating into clear-cut biological returns. http://link.springer.com/article/10.1007/s00267-013-0223-5

Animal movement is a pivotal element of many ecological processes, and on ocean-exposed sandy shores, ghost crabs (genus Ocypode) undertake extensive nocturnal forays on the beach surface. Because crab populations are also threatened by vehicle traffic, indicators that can detect sublethal effects before population declines are manifest are important. To this end, we tested on a barrier island in Eastern Australia whether movement patterns of crabs respond predictably to disturbance by vehicles; this was done by tracking (using the spool-and-line technique) crabs at night in beach sections open and closed to traffic. Beach traffic not only halved population densities of crabs on the unvegetated beach seawards of the dunes, but it also fundamentally changed crab behaviour and movement: individuals from beach areas rutted by tyre tracks travelled shorter distances in a more erratic zigzag pattern, and they had significantly compressed home ranges. Such behavioural changes linked to human pressures could be well suited as an early warning signal for wider negative ecological impacts (as demonstrated by reduced abundances). They also emphasize the need to incorporate sublethal effects into the assessment and management of ecological changes resulting from beach recreation.

Human pressures on coastlines are increasing globally, particularly on urban beaches where maintenance of sand budgets and erosion control are the main focus of current shoreline management. By contrast, biological attributes are rarely considered and few, if any, ecological indicators are routinely monitored on beaches. Abundance of ghost crabs (genus Ocypode ) generally responds predictably to human stressors, and is thus a potentially suitable ecological indicator for beaches. The crabs construct burrows with a single, prominent opening at the surface, and population sizes are commonly estimated by counting the number of these burrow openings. While such ‘burrow counts’ are attractive as a low-cost and simple monitoring technique, they may violate a key performance criterion of indicators: not to be overly sensitive to expected sources of interference. On urban beaches such interference is human trampling and, consequently, we evaluated its influence on the performance of burrow counts. The effects of short-term, intense human trampling on numbers and sizes of crab burrows were measured in a series of impact experiments, in which pedestrian trampling was repeatedly applied over 5 h on 4 consecutive days. Burrow counts were highly sensitive to interference from short-term trampling disturbance, which can substantially bias population estimates inferred from such counts. Importantly, burrow densities recovered overnight and apparent shifts in entrance size structures recorded immediately after the trampling impacts were also no longer evident on the following day. Thus, short-term trampling shifted parameter estimates without significant biological effects underpinning such changes—a clear case of bias. Although crab density and size structure are susceptible to artefacts caused be human trampling, they remain valuable indicators for sandy beaches, if interference by pedestrians is small in field measurements or can be accommodated in numerical analyses.

Sandy beaches comprise one of the most important coastal resources worldwide, providing habitats to threatened vertebrates, supporting underappreciated invertebrate biodiversity, and delivering crucial ecosystem services and economic benefits to mankind. Monitoring of the natural resource condition of sandy beaches and assessments of the ecological impacts of human disturbance are, however, rare on sandy shores. Because a crucial step in developing beach monitoring is to identify and test biological indicators, we evaluated the utility of using population densities of ghost crabs (genus Ocypode) to measure how beach biota respond to human pressures. Densities of crabs--estimated via burrow counts--were quantified at two sites exposed to high and low levels of human disturbance on an urban beach in eastern Australia. Human disturbance consisted of pedestrian trampling and shoreline armouring which led to the loss of dune habitat. Overall, crab numbers were halved in disturbed areas, but contrasts between impact and control sites were not necessarily consistent over time and varied between different levels of the shore: stronger and more consistent effect sizes were recorded on the upper shore than further seawards. In addition to lowering crab densities, human disturbance also caused shifts in intertidal distributions, with a greater proportion of individuals occurring lower on the shore in the impacted beach sections. The number of visible burrow openings also changed in response to weather conditions (temperature and wind). We demonstrate that spatial contrasts of burrow counts are broadly useful to indicate the existence of a human-induced disturbance effect on urban beaches; we also highlight a number of critical, hitherto unknown, issues in the application of this monitoring technique; these encompass three broad dimensions: (1) a need for standardised protocols; (2) unresolved causal links between observed patterns and putative pressures; and (3) uncertainties of how organisms responds specifically to both natural and human changes of environmental conditions on sandy shores.

Beach and coastal dune systems are increasingly subjected to a broad range of anthropogenic pressures that on many shorelines require significant conservation and mitigation interventions. But these interventions require reliable data on the severity and frequency of adverse ecological impacts. Such evidence is often obtained by measuring the response of 'indicator species'.Ghost crabs are the largest invertebrates inhabiting tropical and subtropical sandy shores and are frequently used to assess human impacts on ocean beaches. Here we present the first global meta-analysis of these impacts, and analyse the design properties and metrics of studies using ghost-crabs in their assessment. This was complemented by a gap analysis to identify thematic areas of anthropogenic pressures on sandy beach ecosystems that are under-represented in the published literature.Our meta-analysis demonstrates a broad geographic reach, encompassing studies on shores of the Pacific, Indian, and Atlantic Oceans, as well as the South China Sea. It also reveals what are, arguably, two major limitations: i) the near-universal use of proxies (i.e. burrow counts to estimate abundance) at the cost of directly measuring biological traits and bio-markers in the organism itself; and ii) descriptive or correlative study designs that rarely extend beyond a simple 'compare and contrast approach', and hence fail to identify the mechanistic cause(s) of observed contrasts.Evidence for a historically narrow range of assessed pressures (i.e., chiefly urbanisation, vehicles, beach nourishment, and recreation) is juxtaposed with rich opportunities for the broader integration of ghost crabs as a model taxon in studies of disturbance and impact assessments on ocean beaches. Tangible advances will most likely occur where ghost crabs provide foci for experiments that test specific hypotheses associated with effects of chemical, light and acoustic pollution, as well as the consequences of climate change (e.g. species range shifts).

Complexity is increasingly the hallmark in environmental management practices of sandy shorelines. This arises primarily from meeting growing public demands (e.g., real estate, recreation) whilst reconciling economic demands with expectations of coastal users who have modern conservation ethics. Ideally, shoreline management is underpinned by empirical data, but selecting ecologically-meaningful metrics to accurately measure the condition of systems, and the ecological effects of human activities, is a complex task. Here we construct a framework for metric selection, considering six categories of issues that authorities commonly address: erosion; habitat loss; recreation; fishing; pollution (litter and chemical contaminants); and wildlife conservation. Possible metrics were scored in terms of their ability to reflect environmental change, and against criteria that are widely used for judging the performance of ecological indicators (i.e., sensitivity, practicability, costs, and public appeal). From this analysis, four types of broadly applicable metrics that also performed very well against the indicator criteria emerged: 1.) traits of bird populations and assemblages (e.g., abundance, diversity, distributions, habitat use); 2.) breeding/reproductive performance sensu lato (especially relevant for birds and turtles nesting on beaches and in dunes, but equally applicable to invertebrates and plants); 3.) population parameters and distributions of vertebrates associated primarily with dunes and the supralittoral beach zone (traditionally focused on birds and turtles, but expandable to mammals); 4.) compound measurements of the abundance/cover/biomass of biota (plants, invertebrates, vertebrates) at both the population and assemblage level. Local constraints (i.e., the absence of birds in highly degraded urban settings or lack of dunes on bluff-backed beaches) and particular issues may require alternatives. Metrics – if selected and applied correctly – provide empirical evidence of environmental condition and change, but often do not reflect deeper environmental values per se. Yet, values remain poorly articulated for many beach systems; this calls for a comprehensive identification of environmental values and the development of targeted programs to conserve these values on sandy shorelines globally.

Recreational beach use with off-road vehicles is popular, but potentially harmful from an environmental perspective. Beaches are important habitats to invertebrates such as ghost crabs of the genus Ocyopde, which excavate extensive and elaborate burrows. Ghost crabs are sensitive to human pressures and changes in burrow architecture may thus be a consequence of disturbance by vehicles--the predictive hypothesis of this article. This was tested during the austral spring and summer by comparing 305 burrow casts between beaches open and closed to vehicles in Eastern Australia. Traffic influenced burrow architecture: there were smaller crabs on vehicle-impacted beaches, and after the peak traffic period (Christmas and New Year holidays), these crabs had tunnelled deeper into the sediment on shores rutted by cars. Crabs constructed all types of previously described burrows, but, significantly, smaller crabs from vehicle-impacted beaches simplified their shapes following heavy traffic disturbance from four (I, J, Y, M) to only two types (I, Y). These data support a model of active behavioural responses to disturbance from vehicles, extending the known effects of beach traffic to impacts on behavioural traits of the beach fauna.

Increased storminess is a likely consequence of global climate change; its effects may be most dramatic on coasts dominated by sandy beaches. This scenario demands that the impacts of storms and the role of armouring structures, constructed as storm defences, are better understood. Here, we assess how a relatively small storm affected beach morphology and macrobenthos, and whether a seawall can modulate such impacts. The study system was a small (