Long-term spatial dynamics in vegetated seascapes: fragmentation and habitat loss in a human-impacted subtropical lagoon

2015 ◽  
Vol 37 (1) ◽  
pp. 200-214 ◽  
Author(s):  
Rolando O. Santos ◽  
Diego Lirman ◽  
Simon J. Pittman
2019 ◽  
Vol 111 (2) ◽  
pp. 204-215
Author(s):  
Sarah I Duncan ◽  
Ellen P Robertson ◽  
Robert J Fletcher ◽  
James D Austin

Abstract For species with geographically restricted distributions, the impacts of habitat loss and fragmentation on long-term persistence may be particularly pronounced. We examined the genetic structure of Panama City crayfish (PCC), Procambarus econfinae, whose historical distribution is limited to an area approximately 145 km2, largely within the limits of Panama City and eastern Bay County, FL. Currently, PCC occupy approximately 28% of its historical range, with suitable habitat composed of fragmented patches in the highly urbanized western portion of the range and managed plantations in the more contiguous eastern portion of the range. We used 1640 anonymous single-nucleotide polymorphisms to evaluate the effects of anthropogenic habitat modification on the genetic diversity and population structure of 161 PCC sampled from across its known distribution. First, we examined urban habitat patches in the west compared with less-developed habitat patches in the east. Second, we used approximate Bayesian computation to model inferences on the demographic history of eastern and western populations. We found anthropogenic habitat modifications explain the genetic structure of PCC range-wide. Clustering analyses revealed significant genetic structure between and within eastern and western regions. Estimates of divergence between east and west were consistent with urban growth in the mid-20th century. PCC have low genetic diversity and high levels of inbreeding and relatedness, indicating populations are small and isolated. Our results suggest that PCC have been strongly affected by habitat loss and fragmentation and management strategies, including legal protection, translocations, or reintroductions, may be necessary to ensure long-term persistence.


Zootaxa ◽  
2019 ◽  
Vol 4651 (2) ◽  
pp. 305-329
Author(s):  
FRED KRAUS

I describe five new species of Lepidodactylus from New Guinea or adjacent islands that are members of Brown & Parker’s (1977) phenetic Groups I and II and belong to the clades identified as the L. orientalis, L. pumilus, and L. novaeguineae groups of Oliver et al. (2018a). One of the new species is restricted to an isolated mountain range on New Guinea; the remainder inhabit offshore islands ranging from 3–250 km from New Guinea. These species are distinguished from their congeners primarily by unique combinations of toe lamellar numbers and shape, numbers and distribution of enlarged precloacal/femoral scales and pores, toe webbing, toe width, and color pattern. These clades are ancient, and the ancestor of one of them has been on the East Papuan Composite Terrane for at least 28 MY, highlighting the long-term importance of that former large island in generating regional biodiversity. At least one, and probably three, of the new species are inhabitants of forest interiors; one occupies disturbed coastal areas; and the habitat of the last is currently unsurmisable. All of the new species likely have restricted geographic distributions, with four of them being limited to one or a few small islands. As a result of their small ranges, rapid habitat conversion in the ranges of some of these species, and the threat of further habitat loss in the others, most of these species are of conservation concern although it is uncertain if any of them is under immediate threat. 


2019 ◽  
Vol 62 (4) ◽  
pp. 323-326
Author(s):  
Danielle Catherine Hatt ◽  
Ligia Collado-Vides

Abstract Standing stocks of the calcifying algae, Halimeda and Penicillus, have remained stable over the 10 years surveyed (2007–2017) in Florida Bay (USA), a subtropical lagoon. The maximum contribution of calcium carbonate (CaCO3; 779.75 g m−2) was lower compared to tropical lagoons. Halimeda was more abundant and had higher inorganic:organic carbon ratios compared to Penicillus. The abundance of Penicillus varied across the surveyed sites, Sprigger Bank, Bob Allen Keys, and Duck Key, while its inorganic:organic carbon ratios did not vary significantly. Our long-term study provides a critical baseline that can help understand fluctuations in carbonate sediment production by calcareous algae in subtropical coastal waters.


Oryx ◽  
2007 ◽  
Vol 41 (1) ◽  
pp. 44-50 ◽  
Author(s):  
Peter S. Harlow ◽  
Martin Fisher ◽  
Marika Tuiwawa ◽  
Pita N. Biciloa ◽  
Jorge M. Palmeirim ◽  
...  

The endemic Fijian crested iguana Brachylophus vitiensis, categorized as Critically Endangered on the IUCN Red List, has been recorded from several islands in western Fiji. We conducted a survey for the crested iguana on 12 uninhabited and five inhabited islands in the Yasawa and Mamanuca archipelagos of western Fiji in September 2000. Night searches for sleeping iguanas along a total of 11.2 km of forest transects suggest that crested iguanas are either extremely rare or extinct on all of these islands. Although we collectively searched a total of 44 km of transect over 123 person hours, we located crested iguanas on only four islands: three small uninhabited islands (all <73 ha) and one large inhabited island (22 km). In July 2003 we resurveyed two islands identified as having the best potential for the long-term conservation of crested iguanas, and found that populations were continuing to decline. We suggest that the scarcity of crested iguanas on all islands surveyed is due to the combination of habitat loss and the introduction of exotic predators. All islands surveyed have free ranging goats, forest fires have occurred repeatedly over the last few decades, and feral cats are established on many islands. To reverse the population decline of this species immediate intervention is required on selected islands to halt continuing forest degradation and to clarify the effects of introduced predators.


2007 ◽  
Vol 55 (5) ◽  
pp. 1-8 ◽  
Author(s):  
S.B. Watson ◽  
M. Charlton ◽  
Y.R. Rao ◽  
T. Howell ◽  
J. Ridal ◽  
...  

The Laurentian Great Lakes of North America are a drinking water source for millions of Canadian and US consumers. These waterbodies have undergone extensive change over the past century as a result of widespread degradation and remediation. Many of the Lakes are prone to taste and odour (T&O), and although these outbreaks have been poorly monitored, evidence suggests that they are increasing in frequency. Tracing and controlling T&O in such large systems presents a challenging task, due to their physical size and complexity. This paper presents an overview of recent investigative and management approaches to T&O in Lake Ontario and its outflow, the St. Lawrence River. We have identified three distinct patterns of T&O in these source-waters, caused by geosmin and 2-methylisoborneol and differing in their planktonic and benthic sources, and temporal and spatial dynamics. Each pattern has required a different approach by scientists and management, in partnership with the water industry. We have shown these T&O outbreaks are caused and moderated by physical, chemical and biological mechanisms over a spectrum of spatial and temporal scales. Canadian municipalities affected by these outbreaks have been key to the investigation of the links between T&O and ecosystem processes with the aim to develop more proactive water treatment and long-term management.


Oryx ◽  
2017 ◽  
Vol 52 (2) ◽  
pp. 292-299 ◽  
Author(s):  
Mircea G. Hidalgo-Mihart ◽  
Fernando M. Contreras-Moreno ◽  
Alejandro Jesús de la Cruz ◽  
Rugieri Juárez-López

AbstractThe fragmentation of jaguarPanthera oncapopulations as a result of habitat loss is considered to be one of the main challenges for the conservation of the species. Corridors have been proposed as a means of maintaining connectivity and the long-term viability of jaguar populations. The corridor that connects the jaguar conservation units of Calakmul and Laguna de Terminos in Mexico has been considered to be a link for the movement of individuals between these units but its functionality had yet to be verified. During 2012–2014 we divided the corridor into four sections, where we used camera traps to verify the corridor's functionality. We obtained 106 photographs of jaguars, proving the presence of jaguars (including resident jaguars and females) in three of the corridor sections. We did not record any individuals in more than one section of the corridor. The presence of several resident jaguars and females throughout the corridor suggests that portions of the corridor should be incorporated into the Calakmul and Laguna de Terminos jaguar conservation units. Nevertheless, to confirm that the corridor is fully functional it is necessary to obtain evidence of movement of jaguars among the various sections of the corridor. Our results suggest that the area should be included in regional conservation strategies.


2017 ◽  
Vol 45 (2) ◽  
pp. 147-154 ◽  
Author(s):  
EVAN J. PICKETT ◽  
MELANIE CHAN ◽  
WENDA CHENG ◽  
JOHN ALLCOCK ◽  
SIMBA CHAN ◽  
...  

SUMMARYThe East Asian–Australasian flyway contains some of the most threatened habitats in the world, with at least 155 waterbird species reliant on the tidal habitats it comprises. The black-faced spoonbill (Platalea minor) is an iconic endangered species distributed across the coast of East Asia. Its population suffered a severe decline into the 1990s, but extensive monitoring and conservation interventions have aided a substantial recovery of the species. We used a population viability analysis based on data collected over the past two decades in conjunction with species distribution models to project spatially explicit models of population change for the next 35 years. Over nearly all scenarios of habitat loss and climate change, the global spoonbill population was projected to increase in the short-term due to low population numbers likely well below current population carrying capacities. However, climate change and habitat loss together threaten the recovery of the spoonbill population such that, by 2050, population declines are apparent as a consequence of these cumulative impacts. These threats are also cryptic and represent a challenge to the conservation of species recovering from anthropogenic impacts; observed population increases can hide large reductions in habitat suitability that threaten the long-term viability of species.


2019 ◽  
Vol 73 (11) ◽  
pp. 1504-1536 ◽  
Author(s):  
Ludo Glimmerveen ◽  
Sierk Ybema ◽  
Henk Nies

What happens when people try to ‘transcend’ organizational boundaries and engage with so-called outsiders? Current boundary-work literature does not fully account for the processual, dispersed, and political dynamics triggered by such efforts. To address this shortcoming, this article builds on an ethnographic study of a professional care provider’s attempts to engage local citizens within one of its care homes. We analyze how actors negotiate the parameters of outsider engagement – that is, how they interactively (re-)erect and (re-)efface boundaries between actors (Who is engaged?), issues (What is their engagement about?), and positions of authority (Does local engagement affect central decision-making?). We contribute to extant theorizing by, first, explicitly scrutinizing boundary work’s temporal and spatial dynamics. Testifying to the importance of analyzing temporal sequences, we show how attempts at transcending boundaries intensified boundary work on multiple organizational platforms. Paradoxically, inclusionary efforts evoked exclusionary effects (and vice versa) as actors came to contest and, eventually, redefine ‘appropriate’ insider–outsider relations. Second, our analysis highlights how the political effectiveness of an inclusive and non-hierarchical approach still, ironically, depends on ongoing hierarchical support and managerial enforcement. Third, our article makes a case for the adoption of long-term, multi-sited methodologies when studying the everyday dynamics of boundary-work processes.


Rangifer ◽  
2013 ◽  
Vol 2 (1-App) ◽  
pp. 57
Author(s):  
Andrey N. Petrov ◽  
Anna V. Pestereva ◽  
Leonid A. Kolpashchikov ◽  
Vladimir V. Mikhailov

This report presents preliminary results of mapping and analyzing wild reindeer spatial dynamics in Taimyr, Russia. We collected, spatially referenced, and systematized comprehensive aerial and land survey information spanning from 1969 to 2003, which is the most complete long-term data available about a wild reindeer herd in Eurasia. The report introduces some of the mapping products and presents a summary of our observations on spatiotemporal changes in reindeer distribution and migration. Using these data and new digital products in the GIS (Geographic Information Systems) environment, we were able to observe the long-term shift of the Taimyr Reindeer Herd's summer, winter, and calving areas to the east and south with a simultaneous expansion of the habitat. We identified and confirmed locations of large reindeer concentrations (herds) seasonally formed throughout the study period. Using the most recent summer survey data (2009) we also were able to confirm the existence of two major migration flows in the fall: eastern (most reindeer) and western.


Cybergeo ◽  
2018 ◽  
Author(s):  
Adrien Lammoglia ◽  
Samuel Leturcq ◽  
Étienne Delay
Keyword(s):  

Sign in / Sign up

Export Citation Format

Share Document