Paddling impacts on aquatic macrophytes in inland waterways

Paddling benefits people’s health and wellbeing but can impose pressure on aquatic ecosystems. Negative effects intensify if many recreationists simultaneously use the same waterbody, sites, or sections and at high intensity. Therefore, especially waterbodies attracting high numbers of people are threatened to become ecologically degraded. We examined effects of paddling on aquatic macrophytes in waterways of the Spreewald biosphere reserve, one of the most popular destinations for water tourism in Germany. Nine waterway sections were investigated with varying boating intensity gradients from low to highly frequented with medians of 1 to 239 boats per day, respectively. Mechanical damage to emergent vegetation increased with boating intensity depending on waterway width: Observed overall and group-specific damage decreased at widths > 15 m despite high paddling intensity. Diversity (species richness and Shannon-index) decreased with increasing boating intensity; however, in at least one waterway less shade has masked boating effects resulting in high plant diversity despite high paddling intensity. Overall, plant damage and diversity effects were more pronounced between closed reference waterways and open paddling waterways than between the intensity gradients studied, suggesting that critical impacts were already reached at moderate paddling frequency. Furthermore, paddling significantly shaped species composition between sites, and had stronger negative effects on submerged than on emergent macrophytes, and on rigid than on flexible growth forms. In waterways open for boating, where potential contact with paddle strokes or canoe hulls is high, the growth of rigid, less flexible plant species was impaired. In contrast, submerged species with flexible stems and branches, soft leaves, and reproducing from fragments were found independent from boating intensity. Further, waterways closed for boating provided refugia and regeneration niches indicated by rare or endangered species more frequently found therein.     

Psychological adjustment in children after traumatic disfiguring injuries: a 12-month follow-up

The psychological adjustment of 57 children (age range, 3 to 12 years) who sustained mutilating traumatic injuries to the face or upper or lower extremities was assessed over a 12-month interval. The injuries had occurred as a result of boating, lawn mower, or home accidents or dog bites. Within 5 days of the traumatic event, 98 percent of the children were symptomatic for posttraumatic stress disorder, depression, or anxiety. One month after the injury, 82 percent were symptomatic. Symptom frequency had declined by the time of the 3-month and 6-month evaluations, but 44 percent of the children continued to report symptoms at 12-month follow-up visits, and 21 percent met the diagnostic criteria for posttraumatic stress disorder. Typical symptoms included flashbacks, fear of re-injury, mood disorders, body-image changes secondary to disfigurement, sleep disturbances, and anxiety. These findings support the importance of psychological evaluation and treatment of children who suffer mutilating injuries that require the attention of plastic surgeons.     

Disentangling invasion processes in a dynamic shipping-boating network

The relative importance of multiple vectors to the initial establishment, spread and population dynamics of invasive species remains poorly understood. This study used molecular methods to clarify the roles of commercial shipping and recreational boating in the invasion by the cosmopolitan tunicate, Botryllus schlosseri. We evaluated (i) single vs. multiple introduction scenarios, (ii) the relative importance of shipping and boating to primary introductions, (iii) the interaction between these vectors for spread (i.e. the presence of a shipping-boating network) and (iv) the role of boating in determining population similarity. Tunicates were sampled from 26 populations along the Nova Scotia, Canada, coast that were exposed to either shipping (i.e. ports) or boating (i.e. marinas) activities. A total of 874 individuals (c. 30 per population) from five ports and 21 marinas was collected and analysed using both mitochondrial cytochrome c oxidase subunit I gene (COI) and 10 nuclear microsatellite markers. The geographical location of multiple hotspot populations indicates that multiple invasions have occurred in Nova Scotia. A loss of genetic diversity from port to marina populations suggests a stronger influence of ships than recreational boats on primary coastal introductions. Population genetic similarity analysis reveals a dependence of marina populations on those that had been previously established in ports. Empirical data on marina connectivity because of boating better explains patterns in population similarities than does natural spread. We conclude that frequent primary introductions arise by ships and that secondary spread occurs gradually thereafter around individual ports, facilitated by recreational boating.     

Sediment Contaminants and Infauna Associated with Recreational Boating Structures in a Multi-Use Marine Park

Multi-use marine parks achieve conservation through spatial management of activities. Zoning of marine parks in New South Wales, Australia, includes high conservation areas and special purpose zones (SPZ) where maritime activities are concentrated. Although such measures geographically constrain anthropogenic impacts, we have limited understanding of potential ecological effects. We assessed sediment communities and contaminants adjacent to boating infrastructure (boat ramps, jetties and a marina) in a SPZ from the Clyde Estuary in Batemans Marine Park. Metal concentrations and fines content were elevated at boating structures compared to reference sites. Species richness was higher at sites with boating structures, where capitellid polychaetes and nematodes dominated the communities. Changes associated with boating structures were localised and did not extend beyond breakwalls or to reference sites outside the SPZ. The study highlights the benefits of appropriate zoning in a multi-use marine park and the potential to minimise stress on pristine areas through the application of spatial management.     

Recreational boating: a large unregulated vector transporting marine invasive species

Aim Recreational boating is arguably the largest unregulated vector for the introduction and spread of marine invasive species. Hull fouling communities have been recognized to harbour non‐indigenous species (NIS), but presence should not be equated with transport. In this study, we characterize the presence of NIS in hull fouling communities, determine if host vessels transport these species and evaluate the importance of recreational boating as a vector for introduction and spread. Location Coastal British Columbia (BC), Canada. Methods Dive surveys in BC marinas were conducted to record the presence of NIS and to estimate their per cent cover. In addition, a boater questionnaire survey was used to determine common travel and maintenance practices. These results were combined to investigate the potential for recreational boats to transport NIS. Results Nine NIS, including the highly invasive ascidians Styela clava and Botrylloides violaceus, and the macroalga Sargassum muticum, were found in hull fouling communities on recreational boats. Overall, per cent cover was generally low; however, niche areas were commonly fouled, even on active and otherwise clean boats. Fouling of niche areas was not related to either antifouling paint age or travel frequency, and fouling levels were highly variable among individual boats both within marinas and across regions. Main conclusions Recreational boating is a major vector contributing to the spread of marine invasive species. Our results indicate that recreational boats represent a high‐risk vector both for primary introduction and secondary spread of marine NIS and should be subject to vector management regulations.     

Effect of boat noise and angling on lake fish behaviour

The effects of disturbances from recreational activities on the swimming speed and habitat use of roach Rutilus rutilus, perch Perca fluviatilis and pike Esox lucius were explored. Disturbances were applied for 4 h as (1) boating in short intervals with a small outboard internal combustion engine or (2) boating in short intervals combined with angling with artificial lures between engine runs. The response of the fish species was evaluated by high‐resolution tracking using an automatic acoustic telemetry system and transmitters with sub‐minute burst rates. Rutilus rutilus swimming speed was significantly higher during disturbances [both (1) and (2)] with an immediate reaction shortly after the engine started. Perca fluviatilis displayed increased swimming activity during the first hour of disturbance but not during the following hours. Swimming activity of E. lucius was not significantly different between disturbance periods and the same periods on days without disturbance (control). Rutilus rutilus increased their use of the central part of the lake during disturbances, whereas no habitat change was observed in P. fluviatilis and E. lucius. No difference in fish response was detected between the two types of disturbances (boating with and without angling), indicating that boating was the primary source of disturbance. This study highlights species‐specific responses to recreational boating and may have implications for management of human recreational activities in lakes.     

Displacement of epifauna from seagrass blades by boat wake

Due to the increasing accessibility of waterways under coastal development, recreational boating is among the growing disturbances to seagrasses at the local scale. While previous studies indicate that in decreasing and fragmenting seagrass habitat, boating can impact the diverse faunal assemblages associated with this habitat, direct impacts of boat wake on phytal invertebrates have not been assessed. By sampling seagrass blades twice before, immediately after and 1 h after exposure to recreational boat wake, this study documented the displacement of macroinvertebrates from flapping seagrass blades. At wake-exposed sites, up to five-fold decreases in the total abundances of amphipods and polychaetes and two-fold deceases in taxon richness were evident from immediately before to immediately after the disturbance of wake. By contrast, at control sites, the abundance and richness of these taxa remained fairly unchanged during the study and in some cases even increased. Although many of the displaced taxa were mobile, additional sampling indicated that they did not completely recolonize seagrass patches within 1 h of the disturbance. Thus, in places where boat traffic is relatively frequent, permanent depression of abundances of macroinvertebrates in seagrass may occur. This is of concern given that macroinvertebrates fuel fisheries productivity. Thus, in areas with frequent and or intense boating activity, nursery functions of seagrass beds may be severely compromised.     

Recreational Boats and Turtles: Behavioral Mismatches Result in High Rates of Injury

Recreational boats are a dominant feature of estuarine waters in the United States. Boat strike injury and mortality may have a detrimental effect on populations of diamondback terrapins (Malaclemys terrapin), a keystone species in estuarine ecosystems. In Barnegat Bay, New Jersey, 11% of terrapins (n = 2,644) have scars consistent with injuries from boats. Conservative estimates of injury rates from boats increased from 2006 to 2011. When exposed to playback recordings of approaching boat engines of varying sizes and speeds in situ, terrapins did not significantly change their behavior in response to sounds of boat engines of different sizes. The lack of behavioral response of terrapins to boat sounds helps explain high rates of injury and mortality of terrapins and may threaten the viability of terrapin populations. Boater education courses that discuss impacts of boats to wildlife, combined with closure of areas of high terrapin densities to boating, are necessary to protect terrapins and other aquatic species from injury and mortality caused by motorized boats.     

The direct physical,chemical and biotic impacts on Australian coastal waters due to recreational boating

In economically developed countries it is projected that by around 2015 over 50% of a person’s lifetime will become available for leisure. Demand for leisure needs, already strong, will continue to increase. One segment of the market, outdoor nature-based recreation (including tourism), is growing strongly worldwide. A substantial proportion of these activities are water-based. The associated demand for recreational vessels has increased rapidly in recent years and is projected to continue to trend upwards. Australian trends mirror those internationally. Using Australia as a case study, we review the direct physical, chemical and biotic impacts associated with recreational boating in coastal water environments. Major physical impacts include disturbance due to movement of craft in shallow waters (e.g., turbulence) and the effects of anchoring/drag, noise/interference/collision that impacts on wildlife. The most critical chemical impacts result from pollution due to fuels and oils, defouling treatments (even those not legislated in-country), and human waste (e.g., sewage effluent). Important biotic impacts are the potential continued introduction and secondary spread of non-native species. We conclude that while greater research effort will provide more environmentally benign products, with the increasing popularity of recreation vessels, it will be beyond the resources of Australian governments to police legislation effectively. However, based on Australian’s demonstrated engagement with government in terrestrial environmental management, with their deliberate engagement with the boating fraternity, the impacts of recreational boating would be lessened.     

Environmental and ecological changes associated with a marina

Anthropogenic modifications to waterways are common and their ecological consequences must be understood to effectively conserve local biodiversity. The facilitation of recreational boating activities often requires substantial alteration of natural areas, however the environmental and ecological consequences of such alterations are rarely described in the scientific literature. In this study, ecological and physico-chemical conditions were investigated in a recreational boating marina, located inside a marine park on the south-east coast of Australia. Recruitment panels were deployed for 8?weeks both inside and outside the marina, and differences in the composition of the developing fouling communities were observed. The recruitment of taxa, which often have short-lived larvae, was increased inside the marina (bryozoans, spirorbids and sponges) while the recruitment of taxa, which often have longer-lived larvae, was reduced or absent (barnacles, solitary ascidians and non-spirorbid polychaetes). Differences were also observed in environmental conditions inside the marina cf. directly outside. The marina environment had higher turbidity, temperature and pH along with higher concentrations of lead and copper in suspended sediments, while flow rates and trapped sediment loads were reduced inside the marina. The differences observed in the study suggest that there may be marked environmental changes associated with marina developments. The potential ecological consequences of these changes should be a primary consideration during the planning process, particularly for developments in locations of notable ecological value.     

The role of recreational activities in creating fragments of invasive Caulerpataxifolia

Once non-indigenous species are introduced to a new area, secondary spread is important in determining their ecological and economic impacts. Recreational activities may facilitate the secondary spread of invasive species by creating and transporting viable propagules, however to date there are few manipulative experiments that demonstrate the mechanistic basis of their impact. We examined the effect of two of the main aquatic recreational activities, boating and swimming, on the abundance of propagules (fragments) of the invasive green alga, Caulerpataxifolia in southeastern Australia. Surveys of two infested estuaries each with locations of different levels of recreational activity demonstrated that locations with high recreational activity had a significantly greater abundance and biomass of fragments than locations with low recreational activity. Manipulative experiments using beyond BACI type designs showed that both boating and swimming created fragments. A single pass of a motor-boat over C.taxifolia beds significantly increased the biomass of fragments, but only in shallow water. Similarly, swimming in C.taxifolia beds for 5 min significantly increased the biomass of fragments, but only when background levels of fragments were low. This study has provided the first manipulative experiments confirming that recreational activities such as boating and swimming can create propagules of aquatic invasive species. These findings provide scientific justification for targeting management efforts to minimize secondary spread of aquatic invasive species by restricting recreational activities in invaded areas.     

Recreational boats as a vector of secondary spread for aquatic invasive species and native crustacean zooplankton

Recreational boats in tow between lakes are a known vector of the spread of aquatic invading species (AIS), but we have no test of the hypothesis that recreational boats are also a vector of secondary spread of AIS among freshwater ecosystems via in-water transport i.e., while boating between interconnected waterways. In this study, we surveyed recreational boaters travelling into Lake Simcoe (44°25′N, 79°20′W), Ontario, Canada, on their recreational activities, boat maintenance, and travel destinations, measured the degree of vessel fouling, and sampled all standing water and attached macrophytes associated with their vessels. A total of 321 zooplankton individuals comprising 15 different species were collected from the standing water in vessels, including veligers of the invasive zebra mussel Dreissena. The volume of water collected within the vessels significantly increased the number of zooplankton transported. Zooplankton species from pelagic habitats or with planktonic life stages were collected more frequently than species that occupy littoral or benthic habitats, likely reflecting the recreational activities of boaters. Patterns of boater activities, movements and hygiene habits, suggest recreational boating in the Lake Simcoe region is contributing to the spread of native and invasive species into nearby waterways. Our study validates the widespread assumption that recreational boats are an important in-water vector for the secondary spread of both native and invasive zooplankton species. Future management strategies to reduce the spread of AIS should be aimed at increasing awareness of boater hygiene practices, particularly the frequent draining of standing water.     

云贵高原湿地景区人类活动强度的空间分布——以云南省拉市海流域为例

人类活动强度多用于衡量人类对自然生态的影响程度,具有明显的空间差异性。本研究以云南省拉市海流域为例,采用SPOT遥感影像对土地利用数据进行更新,通过对不同土地类型赋权得到格网化的土地利用强度综合指数,并将其作为基础人类活动强度。同时,又纳入了当地的骑马和划船两项主要旅游活动,基于马场位置和马匹数量以及船只数量,采用地理信息系统的核密度分析方法进行空间定量化,并在100 m×100 m空间尺度上与基础人类活动强度进行叠加,得到更为精确的综合人类活动强度,并对其空间差异进行分析。结果表明: 格网化和核密度分析在提高空间分析精度的同时,将空间上的叠加和扩散效应体现出来;在拉市海流域综合人类活动强度图中,水域的入海口处强度值最高,海中心强度值最低,整体强度呈现从四周向中间逐渐减弱的趋势,陆域的居民点为强度最高区域,农业用地聚集区强度值处于中间水平,海拔较高的林区人类活动强度较低;拉市海水域综合人类活动强度值变化最明显,与基础人类活动强度差异较大。云贵高原湿地景区当地特色旅游活动较多,但并未改变其土地利用类型,因而对其进行人类活动强度量化时,需将其另外考虑在内。     

Distribution of recreational boating across lakes: do landscape variables affect recreational use?

1. Because people impact lake ecosystems, it is important to consider factors influencing the human use of freshwater resources. We investigated the influence of the landscape position, as well as lake area, recreational facilities, and distance to highways and urban centres, on lake use by boaters in the Northern Highland Lake District of Wisconsin, U.S.A.
2. In aerial surveys of ninety-nine randomly selected lakes, we did not see boats on over half of the lakes. Of the lakes with boats, we found a strong correlation between the number of boats and lake area. Recreational boats tended to be found on large, accessible lakes with good boating facilities. Boats were not seen on small, stained lakes with few recreational facilities.
3. Regression models showed that lake size and landscape position explained 63% of the variability in the average number of boats per lake and landscape position explained 24% of the variability in boat density on all ninety-nine lakes. Social variables representing the quality of boating facilities and the perception of good fishing explained 70% of the variability in number of boats per lake and 54% of the variation in boat density on all lakes. A combined model using both physical and social variables increased the explanatory power for both number and density. Lake use by boaters was correlated with landscape position, the quality of fishing and the availability of recreational facilities. When the analysis was restricted to the forty-six lakes where boats were found, only the availability of recreational facilities proved a significant predictor of boat density.
4. Our results suggest that lake choice by recreational boaters may be best predicted by a combination of the location of a lake in a regional hydrologic landscape, and considerations of available facilities and perceptions regarding fishing.     

Applying macrophyte community indicators to assess anthropogenic pressures on shallow soft bottoms

Vegetated soft bottoms are under pressure due to a number of anthropogenic stressors, such as coastal exploitation and eutrophication. The ecological value of these biotopes has gained recognition through international conventions and the EU directives, which request methods for assessment of the environmental status of coastal areas. However, currently there is no appropriate method for assessing the status of shallow vegetated soft bottoms in the northern Baltic Sea. Therefore, we developed a macrophyte community index and tested its response in relation to important pressures (eutrophication and boating activity) and natural gradients (topographic openness, depth and salinity) on shallow bays in the northern Baltic Sea. The macrophyte index, and hence the proportion of sensitive to tolerant species, decreased with increasing phosphorus concentration, turbidity and level of boating activity, while the cumulative cover of macrophytes only showed a negative trend in response to increasing turbidity. Juvenile fish abundance was positively related to the index, indicating importance of sensitive macrophyte species for ecosystem functioning. As the index was tested in a wide geographic area, and showed a uniform response across natural gradients, it is a promising tool for assessment of environmental status that may be applied also in other vegetated soft-bottom areas.     

惠州西湖底泥中氮磷特征的初步研究

惠州西湖为典型的亚热带城市浅水湖泊.为了调查该湖泊底泥性质了解底泥对水质的影响.2004年8月在惠州西湖5个子湖(南湖、丰湖、平湖、菱湖和鳄湖)采集了6个底泥柱样,对其含水率、烧失量(LOI)、总氮(TN)、总磷(TP)、藻类可利用性磷(AAP)和粒度的垂向特征进行了初步研究.结果表明,各子湖中南湖内源负荷最大,底泥中的LOI、TN、TP和AAP含量高于其他湖区数倍以上,表层值较高,表明曾遭受过严重的污染,而其它湖区的垂向变化不明显.底泥成分以粘土、粉砂为主,水体混浊度高可能与底泥粒径较小以及鱼类和游船活动的强扰动性有关.     

Economic effects and the efficacy of intervention: exploring unintended effects of management and policy on the spread of non-indigenous species

Models have been well developed describing human movements as vectors of the spread of non-indigenous species (NIS). However, to be maximally useful, predictions need to be integrated with management models of how different policies change human behaviour and lead to concurrent changes in invasion risk. Using the dispersal of freshwater organisms by recreational boaters as our study system and mandatory boat washing as our management strategy, we conducted a survey of recreational boaters (n = 580 respondents, t = 2354 boating trips) in Ontario, Canada, and performed counterfactual analysis of boater behavior across different management options. We developed a model to quantify three responses to mandatory boat washing policies: (1) the continued use of a policy lake; (2) switching to a non-policy lake (“trip redistribution”); or, (3) a reduction in boating trips (“trip loss”). We found that boater and locational traits did not have a significant effect, but even modest user fees at washing stations greatly influenced trip redistribution and loss, explaining 87% of the variation in boater choices. These results indicate that user fees can strongly reduce the effectiveness of boat washing programs to mitigate invasion risk and could have unintended local economic effects, supporting the need to minimize boater expense as a program goal. In contrast, only minor redistribution and loss occurred if users washed but did not pay, and when taken together with the lack of effect for boater and locational traits, suggest that simple human-mediated dispersal models would be sufficient to prioritize management actions under “zero fee” scenarios. Simulating management scenarios using an existing spread model for 10 aquatic NIS in Ontario further emphasized the benefit of zero fees. Although averted invasions increased monotonically with effort (number of lakes with washing stations), the relative effectiveness (number of invasions averted per unit effort) was high even with management of a single lake, given zero fees, but required washing stations at far more lakes to maximize relative effectiveness when user fees were imposed.     

Spinal injuries due to front-end bale loaders.

Of 22 patients admitted to Plains Health Centre, Regina, from January 1979 to April 1986 with spinal injuries due to farming accidents, 7 had injuries related to tractor-mounted front-end bale loaders. In contrast, none of the 12 patients admitted with farm-related spinal injuries from 1974 through 1978 had injuries related to bale loaders. All seven injuries occurred when a front-end loader was used to move a large, round hay bale. In each case when the loader arms were raised past the horizontal plane the bale rolled back onto the unprotected tractor operator. There were five thoracic injuries, one cervical injury and one lumbar injury. All seven bony injuries healed. Four of the patients had permanent neurologic sequelae; two of the four had paraplegia. All seven patients suffered disability that impaired work performance; all five farmers suffered some loss of income. None of these injuries would have occurred if available safety equipment had been in place.     

Recreation ecology: Effects of trampling on plants and corals

Recreation ecology deals with the impact of outdoor recreation on natural or seminatural environments. The main activity considered in this review is walking (or trampling) but the effects of camping, horse riding, off-road vehicles, trail bikes and boating have all been studied(1-4). The different levels of enquiry reviewed here, from overall community changes to plant (or in one case coral) morphology and plant anatomy, have gone hand in hand with management recommendations based on fundamental work. The newer approaches include genetic analysis, a new structure for impact theory and more accurate predictive techniques for management.