Amazonian freshwater habitats experiencing environmental and socioeconomic threats affecting ...

14 Pages·2015·1.18 MB·English

Ambio2015,44:412–425
DOI10.1007/s13280-014-0610-z
REPORT
Amazonian freshwater habitats experiencing environmental
and socioeconomic threats affecting subsistence fisheries
Cleber J. R. Alho, Roberto E. Reis, Pedro P. U. Aquino
Received:1August2014/Revised:22October2014/Accepted:17December2014/Publishedonline:9January2015
Abstract Matching the trend seen among the major large RiversforFisheries,heldinPhnomPenh,Cambodiain2003,
riversoftheglobe,theAmazonRiveranditstributariesare expressedalarmthatfreshwaterfishstockshavedeclinedin
facing aquatic ecosystem disruption that is affecting many of the world’s largest rivers (Dudgeon et al. 2006).
freshwater habitats and their associated biodiversity, Further evidence of this concern was the initiative of the
including trends for decline in fishery resources. The United Nations General Assembly, which proclaimed the
Amazon’saquaticecosystems,linkednaturalresources,and period from 2005 to 2015 as the International Decade for
humancommunitiesthatdependonthemareincreasinglyat Action—’’WaterforLife.’’Theresolutioncallsforagreater
riskfromanumberofidentifiedthreats,includingexpansion focus on water issues to achieve freshwater conservation.
of agriculture; cattle pastures; infrastructure such as The document ‘‘Living Planet Report 2014—Species and
hydroelectric dams, logging, mining; and overfishing. The spaces, people and places’’ (http://wwf.panda.org/about_
forest, which regulatesthe hydrological pulse, guaranteeing our_earth/all_publications/living_planet_report/)organized
the distributionofrainfall and stabilizing seasonalflooding, by WWF International, Zoological Society of London,
hasbeenaffectedbydeforestation.Floodingdynamicsofthe Global Footprint Network, and Water Footprint Network,
AmazonRiversareamajorfactorinregulatingtheintensity points outthatalthough human beingsare aproductofthe
andtimingofaquaticorganisms.Thisstudy’sobjectivewas natural world, we have become the dominant force that
toidentify threatstothe integrityoffreshwaterecosystems, shapesecologicalandbiophysicalsystems.Indoingso,we
andtoseekinstrumentsforconservationandsustainableuse, are not only threatening our health, prosperity, and well-
taking principally fish diversity and fisheries as factors for being, but our very future. Human well-being depends on
analysis. naturalresourcessuchaswaterandfish,aswellasecosystem
services.
Keywords Amazon basin (cid:2) Biodiversity (cid:2) Furthermore, biodiversity contributes to safeguarding
Fishery resources (cid:2) Freshwater habitats (cid:2) subsistence use for traditional human communities (Mil-
Environmental and socioeconomic threats (cid:2) lennium Ecosystem Assessment 2005). The document of
Seasonal flooding the Intergovernmental Panel on Climate Change (IPCC)
heldinYokohama,Japan,March25–29,2014,statedthata
largefractionofbothterrestrialandfreshwaterspeciesface
INTRODUCTION increased extinction risk under projected climate change
during and beyond the twenty-first century, especially as
Human uses of natural resources have affected the fresh- climate change interacts with other stressors, such as
water ecosystems and the surrounding terrestrial environ- habitat modification, over-exploitation, pollution, and
mentduringtherecentdecadesoflandusealongallthelarge invasive species (IPCC 2014).
riversontheplanet.Therehasbeenworldwideconcernover From a biodiversity perspective, the Amazon basin is
aquatic ecosystems, with freshwater biodiversity being the unequaled, with its aquatic habitats that are home to the
overriding conservation priority. River fisheries experts, world’s richest assemblages of freshwater flora and fauna,
meeting at the Symposium on the Management of Large includingreptiles(Caimancrocodilus,Melanosuchusniger
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Ambio2015,44:412–425 413
among other crocodiles, Podocnemis expansa, P. unifilis, alterations, overfishing, and environmental degradation,
P. sextuberculata, and other turtles); amphibians; aquatic and its fishery has been declining considerably over the
habitat-dependent birds, with good indicators of habitat recent years (Baran and Myschowoda 2008; Dugan et al.
quality (Harpia harpyja, Morphnus guianensis, 2010).
Neomorphus squamiger, Penelope pileata, Simoxenops Taking water discharge as a parameter, the Amazon
ucayalae, Synallaxis cherriei); mammals (otters such as River discharges 219000m3/s, while another of the
Pteronura brasiliensis and Lontra longicaudis; river dol- world’slargerivers,theCongoRiverinAfrica,discharges
phins such as Inia geoffrensis and Sotalia fluviatilis, and 41800m3/s (Reis 2013). The Amazon River is the largest
manatee Trichechus inunguis); and more than 2200 fish single source of freshwater runoff on Earth, representing
species (Albert and Reis 2011; Alho 2011). some15–20%ofglobalriverflow(SalatiandVose1984).
Othermammalspecieslifehistoryofwhichisconnected Amazonianbiodiversityisnotonlyasourceofbiological
with water are marsupials such as Chironectes minimus, and scientific wonder and fascination. The wealth of bio-
Micoureus demerarae, Marmosops noctivagus, and logicalresourcesfoundintheAmazonbiomehasprovento
Marmosa murina. Wild rodents strongly linked to habitats be of enormous benefit to human well-being (Alho 2012).
closetowaterarethesemiaquaticNectomyssquamipesand From wood, foods, and beverages to medicines and indus-
the ‘‘toro´’’ arboreal bamboo rat Dactylomys dactylinus trialproductsderived,forexample,fromtherubbertree,the
usually seen vocalizing on branches over the water of biologicaldiversityoftheAmazonforesthashadaprofound
rivers and seasonal lakes. Large mammals also exhibit effectonthedevelopmentofhumansociety.Manyofthese
dependence on aquatic habitats, like the semiaquatic cap- biodiversity secrets have been revealed to Science by
ybara Hydrochoerus hydrochaeris and the tapir Tapirus indigenous peoples, whose livelihoods and cultures depend
terrestris. on their environment and surrounding biodiversity.
The number of Amazonian aquatic species is a clear The Amazonian biodiversity represents a critical
underestimation, because a significant portion of biodi- socioeconomic resource for local people who have long
versity is yet to be discovered and described, particularly relied on fish resources as their major source of food and
considering amphibians and fish. The magnitude of the income (Ruffino 2004, 2005, 2008; Batista et al. 2012).
region is unique: the Amazon basin covers an area of Most notably, three freshwater turtle species are ecologi-
approximately 7000000km2, of which about 58% cally and socioeconomically important in the Brazilian
(4100000km2) is located in Brazil. These species play a Amazon due to traditional human consumption: the giant
fundamentalroleintheaquaticecosystemsbecauseoftheir turtle Podocnemis expansa, the yellow spotted turtle or
highdiversity,andtheecologicalandevolutionarypatterns ‘‘tracaja´’’ Podocnemis unifilis, and the six-tubercled turtle
they exhibit. For example, the Amazonian freshwater fish or ‘‘pitiu´’’ Podocnemis sextuberculata (Alho 1985, 2011).
is very old and has distinct historical origins. Publications The ‘‘va´rzea’’ floodplain appears as the first focus of
like ‘‘Check List of the Freshwater Fishes of South and settlement of the Amazon region, with evidence of the
Central America’’ (Reis et al. 2003), and Bo¨hlke et al. presence of lowland indigenous peoples for about
(1978)pointoutthesteeplyascendingcurveofnewspecies 2000years. These indigenous groups sought the environ-
being described, suggesting that the Amazonian number mentsofriversandstreams(asasourceoffoodandwater)
may exceed 3200 species. to settle their villages and spread through the region.
The Amazon freshwater ecosystems are packed with the However,the hydrographicnetwork ofthe region notonly
highestdiversitiesoffishtobefoundanywhereontheplanet conditionedtheprocessofoccupationbyindigenoustribes
(Le´veˆqueetal.2008;AlbertandReis2011).Thetraditional and, later, by settlers, but also guided the path which the
socioeconomic activities such as fishing and extraction of regional economy would take (Madaleno 2011). The dif-
other livenatural resources havebeenaffectedbythe latest ferent levels of landscape transformation, throughout the
increaseinhumanmigration,causedbynewpossibilitiesof historical human occupation, are synthesized from land-
access to land or driven by new infrastructure projects, scapediversificationtosimplificationandsuppression(Lui
livestock, agriculture, mining, commercial fishing, or other and Molina 2009).
motivations. More than 24 million people live in Brazilian The aim of this paper is to identify and evaluate envi-
Amazonia (Santos et al. 2014). ronmental and socioeconomic threats to Amazonian aqua-
IncomparisonwiththeMekongRiverinSoutheastAsia, tic ecosystems to pursue the conservation and sustainable
one of the largest inland rivers and fisheries in the world, use of its freshwater biodiversity, taking fish diversity and
the total diversity of fish species—estimated at 1000 spe- fisheries as factors for analysis. Two primary concerns are
cies—is significantly lower than that of the Amazon— established: (1) the protection of natural aquatic habitats
estimated at more than 2200 (Albert and Reis 2011). The and (2) the relationship of biodiversity resources, mainly
Mekong basin has been subjected to hydrological fish and river turtles, to local people’s welfare.
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414 Ambio2015,44:412–425
MATERIALS AND METHODS others. Among the interview topics were fishing arts and
artifacts, including the mesh size of fishing nets; the use of
FieldstudieswerecarriedoutinthreedesignatedAmazonian underwater harpoons; period of closed fishing season and
threatened areas, rich in biodiversity, which are known as governmentfinancialsupporttofishermenduringtheclosed
hotspots, providing a good representation of the different season; the role of legislation and fishing regulation
natural aquatic habitats: the Upper Xingu River, the Lower enforcement; conflicts between resident artisan fishermen
TocantinsRiver,andtheMidNegro River,highlightingthe andlargerfishingboats;conflictsbetweenriverinefishermen
aquatic biodiversity, with emphasis on the diversity of fish andsportfishingactivities,aswellasperceptionsofdifferent
and fisheries in their various forms in different kinds of fishing stressors such as riparian deforestation; advance of
aquatic habitats (Fig.1). Ten days were spent working at agriculturalfieldsandcattlepastures;effectsofinfrastructure
each site, visiting different habitats, interviewing riverine such as hydroelectric dams, roads, mining, boat traffic; and
inhabitants, fishermen and other fisheries professionals, and water pollutants. We conducted the interviews to assessthe
covering a sampling path of about 300km in each hotspot. attitudes and perceptions of fishers and other actors toward
Theinterviewswereperformedtodetecttheriverinefisher- theenvironmentalthreatsandfishingconflicts.Surveyswere
men’s perception of the environmental threats and fishing based oninformal group discussions conducted with fishers
conflictsunderaqualitativeordescriptivefocusratherthana and other respondents. Participants within the fishing areas
quantitativeones.Thepeopletargetedbytheinterviewswere were chosenopportunistically. We surveyedfishers belong-
theleadersoftheorganizedfishermen’sinstitutionsandother ing to both traditional subsistence and commercial catego-
actors in the fishing productive web, such as artisanal fish- ries. We qualitatively analyzed positive perceptions, oral
ermen; the owners of ice boats who purchase the fish to histories, and convictions, related to fishing activities, doc-
transporttoconsumercentersandotherintermediatetraders; umented in survey responses to open questions. We also
the leaders of the fishing colonies and cooperatives; and examinedthefishcatchharvestedacrossthestudysites.
80°0’0"W 70°0’0"W 60°0’0"W 50°0’0"W
Venezuela
Atlantic
Suriname Ocean
Branco T
rom 0"
Japurá NegrMoi dRiver betas 0°0’
Patumayo Negro Amazon
Marañón Javary Juruá Madeira Tapajós Xingu ToLRcoiavwneetrir ns
Pacific U Purus
Ocean cayali
Peru Juruena TePles Aragiaia Tocantins 10°0’0"S
Beni Guaporé seri Upper
M Xingu River
a
m
o
ré
Bolivia
Amazonian hotspots
Amazon basin
S
Main rivers 0"
0 245 490 980km 0’
0°
2
Fig.1 Study regions (upper Xingu River, Lower Tocantins River, and mid Negro River) Amazonian threatened areas, rich in aquatic
biodiversityfocusofthefieldwork
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Ambio2015,44:412–425 415
Table1 Study sites in the Upper Xingu River region informing Table2 StudysitesintheLowerTocantinsRiverregioninforming
geographicpositionandaltitudeofeachsite geographicpositionandaltitudeofeachsite
Studysites Latitude Longitude Altitude Studysites Latitude Longitude Altitude(m)
(m)
Baia˜ovillage -2.792377(cid:3) -49.674500(cid:3) 10
HeadwateroftheXingu -12.880338(cid:3) -52.814270(cid:3) 300 JoanaPeresvillage -3.016875(cid:3) -49.748470(cid:3) 12
River
Ituquaravillage -3.031125(cid:3) -49.646270(cid:3) 13
JointureofCulueneand -12.924960(cid:3) -52.825969(cid:3) 302
VilaNovavillage -3.450295(cid:3) -49.608875(cid:3) 13
SetedeSetembrorivers
Moruvillage -3.558638(cid:3) -49.612157(cid:3) 14
UpperCulueneRiver -13.077444(cid:3) -52.885847(cid:3) 310
Tucuru´ıcity -3.756088(cid:3) -49.664309(cid:3) 16
CoronelVanickRiver -13.126701(cid:3) -52.689272(cid:3) 304
Tucuru´ıdam -3.832021(cid:3) -49.643278(cid:3) 70
UpperCoronelVanickRiver -13.237053(cid:3) -52.629633(cid:3) 317
PortodoOnze -3.848169(cid:3) -49.680821(cid:3) 70
UpperSetedeSetembro -13.239636(cid:3) -52.551104(cid:3) 311
River PortoNovo -4.414191(cid:3) -49.387704(cid:3) 73
UpperXinguRiver -14.045409(cid:3) -52.344515(cid:3) 355 SantaRosavillage -4.522811(cid:3) -49.408602(cid:3) 73
Study sites
Table3 Study sites in the Mid Negro River region informing geo-
The Xingu River is a major tributary of the Amazon basin graphicpositionandaltitudeofeachsite
and drains the Brazilian Shield, along with the Tocantins, Studysites Latitude Longitude Altitude
Araguaia, Tapajo´s, and part of the Madeira rivers. The (m)
XinguRiverbasinformstheAquaticEcoregion322ofthe
Fishingarea1 -0.856116(cid:3) -62.765446(cid:3) 35
freshwaterecoregionsmapoftheworld(Abelletal.2008).
Barceloscity -0.966978(cid:3) -62.928499(cid:3) 30
In April 2013, 300km were covered in a motorboat
Bacabalvillage -0.483100(cid:3) -62.921512(cid:3) 29
throughout the headwater region of the Xingu River,
Daracua´ village -0.506514(cid:3) -63.214250(cid:3) 27
sampling the selected areas (Table1).
PontadaTerravillage -0.770953(cid:3) -63.142164(cid:3) 25
This region is an ecotone zone, transition between the
Araca´ River -0.771188(cid:3) -62.937692(cid:3) 28
savanna(Cerrado)biomeofcentralBrazilandtheAmazon
Cuba´ Stream -0.924075(cid:3) -62.917655(cid:3) 29
basin. This study area was chosen for three main reasons:
Mamule´ Stream -0.808618(cid:3) -63.237575(cid:3) 27
(1) the Xingu River represents the tributaries of the right-
MurumuruStream -0.467140(cid:3) -62.928506(cid:3) 39
hand side of the Amazon, which have their headwaters on
Fishingarea2(Calibuque) -0.629722(cid:3) -62.868497(cid:3) 33
the Brazilian Shield; (2) it is an endemic region for fish
species: out of 142 fish species recorded for the Xingu Fishingarea3 -0.464315(cid:3) -63.154313(cid:3) 28
basin, 36 species are endemic (Albert and Reis 2011; Fishingarea4 -0.466774(cid:3) -62.936246(cid:3) 40
Buckup et al. 2011), and most of this endemism occurs in DeminiRiver -0.414927(cid:3) -62.903415(cid:3) 44
the upper Xingu basin; and (3) this region has been under Fishingarea5 -0.833065(cid:3) -63.231232(cid:3) 35
strong threat of deforestation. Fishingarea6(Zamula) -0.865862(cid:3) -62.774625(cid:3) 32
ThesecondselectedstudysitewastheLowerTocantins
River,insideecoregion324—Tocantins–Araguaia—(Abell
et al. 2008). In early June 2013, during the fieldwork, The Negro River was chosen because of the following
approximately 300km were covered along the Tocantins reasons: (1) it is entirely contained inside the lowland
River, sampling the selected sites (Table2). forested area of the Amazon basin, being the major black-
TheLowerTocantinsRiverwasselectedforfieldstudy, water river on the left bank ofthe Amazon River, and it is
considering the following reasons: (1) it is a river strongly the largest black-water river in the world; (2) its black
impacted by a huge hydroelectric dam and reservoir water is poor in mineral nutrients but presents fish ende-
(Me´ronaetal.2010);(2)itpresentshighendemismoffish mism; and (3) traditionally, the region of the Mid Negro
species; and (3) it is an important Amazonian river, River supports an extractive activity of ornamental aquar-
extending up to 2750km in length. ium fish with high socioeconomic relevance.
Finally, the third study site selected was the Mid Negro The identification, characterization, and evaluation of
River, included in ecoregions 314 and 315 (Abell et al. environmental threats to aquatic ecosystems are important
2008). In late July 2013, 310km along the Negro River tools in planning strategic conservation actions. These
were covered, throughout the selected sampling areas aspects of threats were therefore involved in finding ways
adjacent to the town of Barcelos (Table3). to implement policies and environmental management,
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416 Ambio2015,44:412–425
taking into account any particular environmental modifier The upper Xingu region has been under strong pressure
that potentially threatens the Amazonian aquatic environ- of deforestation. Local inspection followed by analysis of
ment. Some ofthese threatstoaquatic ecosystems are ofa satelliteimageshasshownimmenseareasadjacenttovisited
scientific and technical nature, such as those that influence rivers (Culuene, Sete de Setembro, Xingu and others) con-
the structure and function of ecosystems. Others are of a verted into arable fields and cattle pasture, as observed
political and administrative nature, and can often be during the fieldwork. The advance of agriculture has been
anticipatedandavoided,suchasthelegalfisherystandards drivenbygovernmentprograms which encouragedcropsin
that must be implemented and followed. the region. In this area, the Brazilian Savanna biome had
Identifying and qualifying the effect of the threat is already been highly converted by 2008, according to the
somewhat subjective, since it involves not only the eco- deforestation monitoring program PRODES (INPE 2008).
logical focus, but also the socioeconomic point of view. Localobservationsshowthatcropfieldshavenowadvanced
Therefore,theenvironmentalvariablethreattranslatesinto totheedgeoftherivers,alteringoreliminatingtheriparian
the integration of physical and chemical components (soil, forest. This radical deforestation violates Brazilian legisla-
water quality, etc.), as well as the biotic component tion (Brazilian Forest Code, Law 12 651/2012), which
(flooded vegetation, aquatic biodiversity, etc.) and socio- protects a strip of the riparian forest on both sides of the
economicelements(fishing,hunting,captureofturtlesand river as an area of permanent preservation for large rivers.
their eggs, extraction of other natural products, social The seasonally inundated riparian forest constitutes impor-
organization of fishermen, etc.). tant feeding and reproductive habitats for fish. In addition,
A wide range of environmental threats, detected during water contamination through the intensive use of fertilizers
the fieldwork, interact with natural biological and physical and pesticides, which are usually spread by airplane on the
components of the Amazon freshwater ecosystem to crop fields, potentially affects the freshwater wildlife.
change biodiversity productivity and ecological commu- Theregionalsoattractssportfishing,andseveralfishing
nity structure. resortswereobservedalongthevisitedrivers.Localpeople
interviewed reported a decline in fish quantity during the
last 10–15years. They also claim that more recently the
RESULTS size of fish collected by sport fishing has decreased.
While conducting fieldwork in the three designated river The Lower Tocantins River: Infrastructure plants
basins (Upper Xingu River, Lower Tocantins River, and and change in the fish ecological community
Mid Negro River) some environmental threats to the
aquatic ecosystems and their biodiversity were identified The Tocantins River is a major tributary of the Amazon
(Table4). basin and drains, for the most part, from the Brazilian
Theidentifiedenvironmentalandsocioeconomicthreats Shield. The catchment basin of the Tocantins River drains
implythatinadditiontothedeclineinquantityandquality an area of 767000km2 (Me´rona et al. 2010). The last
of fishery resources, based mainly on field observations, portion of these environments is now submerged by the
there is also a reduction in the size of fish being captured, Tucuru´ı hydroelectric reservoir.
and this trend has a strong linkage with regional human The Tocantins basin is the third largest sub-basin of the
demographicgrowthinAmazonia.Asaconsequence,there Amazon River, with an average annual discharge of
is an increasing demand for fish and other natural resour- 11000m3 per second. Its waters are clear and nutrient-
ces, and conflicts have arisen between commercial and poorduetodrainingawaythecrystallineformationsofthe
subsistence fisheries. Brazilian Shield. In this basin occurs a high endemism of
fish species: ‘‘piranhas’’ such as Serrasalmus geryi and
TheUpperXinguRiver:Sportfishingandthethreat S. eigenmanni, and other species like ‘‘aracus’’ Leporinus
of soybean fields affinis and L. taeniatus, the ray Potamo trygonhenley, and
others (Me´rona et al. 2010).
The Xingu basin is the fourth largest watershed of the In1984,theTucuru´ıhydroelectricplantwasbuiltinthe
Amazon, comprising seven percent of the region. The lower portion of theriver. Thedam createda 200km-long
higheraltitudesoftheheadwatersarelocatedinthestateof reservoir with an area of 2875km2 (Me´rona et al. 2010).
Mato Grosso at 800m elevation. The Xingu River runs on Within the upper dam, to the north of the Tocantins River
crystallinerocks,carryingalowamountofsediments,with basin, still freely connected to the rest of the Amazon
clearwater.ThewatersstarttoriseinSeptember–October, basin, some fish species occur that are absent or rare in
reaching the maximum level in March–April. today’s portion under the influence of the dam. The
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ns g
XinguRiver,LowerTocanti NegroMidRiver Notyetrelevant Notyetrelevant Urbansewagepollutants Notrelevant Notrelevant Moderateimpact Moderateconflictbetweenornamentalandsportfishin
er
p
p
U
k:
nssampledduringthefieldwor TocantinsLowerRiver Moderatelyverified Moderatelyverified Urbansewagepollutants Tucuruı´damandplantoperation:overalldrasticeffectsonnaturalhabitatsandfishcommunities Severeimpact Severeimpact Severeconflictamongcommercialfishinginterests
si
a
b
er
v
ri
threatsinthethreeAmazonian XinguUpperRiver Intensivelyverified Observedconversionofnaturalvegetationintohugeareasofsoybeancropfields Potentialcontaminationofwatersfromagriculturalfertilizersandpesticides Moderateandspecificallylocatedeffectfromsmallhydroelectricplants Moderateimpact ModerateimpactintheupperregionbutverysevereintheBeloMontelowerportion(region) Moderateconflictbetweensportandsubsistencefishing
c
mi
o
n
o
onofenvironmentalandsocioec Descriptionofthreat Habitatconversionofripariancommunities,fromexpansionofagriculture,cattleranchingandurbanizationinfloodplains Changesinuplandareas(deforestation,expandingcattleranching,urbanization)resultingindirectlyingreatersedimentloadsandcontaminantssuchasfertilizersandpesticidefromrun-off Directcontaminationofriversfromincreaseddumpingoforganicandsolidwasteintoriversfromexpandingurbanareasandfromactivitiessuchasintensiveagricultureandmining Transformationofaloticenvironmentintoalakeeradicatingorreducingpopulationsofrheophilicfishspecies,andprovidingfavorableconditionsforlenticspeciestoproliferate Changesinhydrologicalregimesthroughconstructionofinfrastructuresuchasroads,portsandnavigationchannels Illegalhuntingandcommerceofwildlife Detectedgrowingnumberofconflictsamongnaturalresourceusers
pti
cri
s
e
d
Table4IdentificationandRiver,andMidNegro Threat Alterationandlossoffishhabitatsduetodeforestationofriparianvegetation Effectofreducedriverflowduetodeforestationofheadwaterareas Effectofenvironmentalcontaminantsonthewaterquality Effectofhydroelectricreservoirsondiversityandfishcommunities Effectofinfrastructureondiversityandfishcommunities Threatstoturtlesandfreshwatermammals Effectsoffishingconflicts
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418 Ambio2015,44:412–425
NegroMidRiver Negativesocioeconomiceffectduetodeclineindemand;fishermenarenowstartingtoseektheirlivelihoodsinotheractivities,suchasagriculture Weaknessoforganizationduetopresentdeclineinornamentalfishing Drasticdeclineindialogueduetodeclineindemandforornamentalfishing Sportfishinginincreasingdemandandornamentalfishingindecline Foreststillwellpreserved
TocantinsLowerRiver Notrelevanthere Severalfishingcoloniesexistbutconflictsarestillsevereduetothelackoffishingregulationandimplementation Conflictsamongsubsistence,commercialandsportfishing Observedstrongpressureonfishingstockstomeetdemand RegionallysubjecttochangeduetodrasticenvironmentalTucuruı´change—dam
XinguUpperRiver NotrelevantintheupperregionbutimportantinthelowerareaofVoltaGrandeXingudo Sportfishingobservedheretobeorganizedtotakeadvantageofimmediateincomeoffishingopportunity Strongorganizationamongownersofsportfishingaccommodationbutlowconcernforsustainability Competitionbetweensportfishingandartisanalsubsistencefishing.Smallerfishsizes. Regionallysubjecttodryingchangeduetointenseandextendeddeforestation
Descriptionofthreat Captureofornamentalfishspeciesforaquariuminternationalcommerce Lackoforganizationalandinstitutionalcapacitytodealwithfishinginaparticipatoryandintegratedmanner Socialorganizationsplayasignificantroleinenablingfisherymanagementtoensuresustainability Overexploitationoffisheryresourcesisobservedwhenfishstocksaresuppressedtoalevelwherefishinginagivenregionisnolongersustainable,thatis,thereisaneedtoincreasefishingeffortandstocksarenotreplenishednaturally ThepublishedliteratureindicatesthatitappearshighlypossiblethatthepredictedclimatechangeoverthenextdecadesmaywellcauseadditionaldamagetoAmazonaquaticecosystems
g
n
Table4continued Threat Declineofornamentalaquariumfishing Effectsofdeficientimplementationoffishiregulation Effectsofdeficientdialoguebetweenparticipantactorsoffishingsocialorganizations Effectsofoverfishing Effectsofglobalclimatechangeonaquaticenvironments
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Tucuru´ıdamhascausedadeclineinfishdiversitylivingin The greatest demand for electricity in the early evening of
thereservoir(Me´ronaetal.2010).Thechangefromalotic each day, as well as lower demand by the industries on
environment in the reservoir eradicated or significantly weekends, leads to a regulation of the amount of water
reduced populations of the rheophilic fish species and passing through the turbines that is released into the river,
provided the conditions for lentic species to proliferate, causing a small increase in river level every night, and a
thereby altering the composition of the local fish commu- reasonabledecreaseinleveleveryweekend.Thesechanges
nity. Detritivorous, herbivorous and insectivorous fish inwaterleveldisruptthenaturalcyclesoffishfeedingand
decreased in abundance in the reservoir. At the same time reproductive behavior, being especially destructive in the
predators, omnivorous and planktivorous species, were spawning season (October–March). Many of these areas
favored and increased in abundance (Me´rona et al. 2010). covered during the fieldwork are shallow, and small vari-
Surveys at local fish markets during the fieldwork showed ations in river level, such as those produced by the reten-
that some abundant commercial species caught in the res- tion of water on the weekends, are sufficient to expose to
ervoir are more adapted to a lentic environment, such as the air and thus kill juvenile fish and eggs laid inthe mass
‘‘mapara´’’Hypophthalmusmarginatus,‘‘tucunare´s’’Cichla of vegetation.
monoculus and Cichla sp., and ‘‘corvina’’ Plagioscion The Tocantins River already has several hydropower
squamosissimus. plants in operation, and several others planned to be built.
Downstream from the dam, the decrease in abundance Theexistingthreatshereidentifiedwillthenbeintensified.
offishspeciesismainlyduetotheregulationofriverflow,
whichgreatlydisturbstheannualfeedingandreproductive The Mid Negro River: Buy a fish and save a tree
cycles of fish. The dam also interrupts migratory routes,
since migratoryfishcannotcrossthebarriercreatedbythe The Negro River is entirely contained in the Amazon
dam, which has no fish ladders, to spawn upriver. Threats sedimentary basin, being the largest tributary of the left
to fish and their aquatic habitats were identified during the bank of the Amazon River. Most of this basin is on a
fieldwork. Fishermen from fishing colonies were inter- lowland floodplain, rising to about 100–250m altitude in
viewed on the lower river region of Tucuru´ı: Colony Z-53 the west and down to about 50m altitude near its mouth.
Breu Branco, Colony Z-43 Porto Novo Jacunda´, both The black water ofthe NegroRiver is extremely lowin
within the reservoir, and Colony Z-34 Baia˜o downstream mineral content.It is 2230kmlong, with a catchment area
fromthereservoir.Intervieweesstatedthattherehasbeena of 696000km2, and an average flow of 28400m3 per
significantdecreaseinfishabundance,bothinthelakeand second, which represents 14% of the annual average flow
downstream, especially in the last 10–15years. of the Amazon basin (Filizola et al. 2010). It is estimated
Local fishermen interviewed condemned the use of that an area of 30000km2 of the Negro basin is flooded
underwater harpoon fishing, a practice that has become seasonally between four and eightmonths of the year.
commonplaceinthelastdecade,asitallowsforthecapture ThecurrentestimateoffishspeciesrichnessintheNegro
of ‘‘tucunare´s’’—when adults feed little with restricted Riverbasinexceeds750describedspecies.Over90species
movement during the period in which they are defending areendemictothebasin,aswellassomemonotypicgenera
spawningterritoriesortakingcareofoffspring,andforthis (Tucanoichthys, Ptychocharax, Atopomesus, Leptobrycon,
reason are notcaptured by the usual gear, like gillnets and Niobichthys, and Stauroglanis) currently found only in this
hooks. The capture of these individuals displaying territo- basin (Petry and Hales 2013). An example of endemic
rialreproductivebehavioraffectsalloffspringandthushas speciesisthesmallcatfishDenticetopsissaulifoundonlyin
agreatpredatoryeffect.Mostrespondentscomplainoflack the headwaters of the Negro River. The fish community
oflegislationandfishingregulationenforcement,reporting composition differs from other parts of the Amazon basin
thatgovernmentofficialsrarelyappearthroughouttheyear primarily in its ecological constraints imposed by nutrient-
or during the period of the closed fishing season. Because poor black waters and low pH.
of this, interviewees stated that the closed season is not The iridescence of some species, such as the cardinal-
observed by most fishermen in the region. tetra Paracheirodon axelrodi, may be an adaptive trait to
Accordingtothemajorityofthefishermen,however,the live in the black water of the Negro River. Interesting eco-
primary responsibility for the sharp decline in fish abun- logical phenomena include large migrations of some fish
dance after closing the Tucuru´ı dam is the daily down- species. The ‘‘jaraqui’’ (Semaprochilodus insignis), for
stream fluctuation of the water level and, especially, the example,migratesfromtheblackwatersoftheNegroRiver
weekly variation in river level as a function of the flow of to the white-water rivers to spawn. There are also unique
water in turbines to attend different hours of energy pro- assemblages of species in deposits of leaves and miniatur-
duction. This area was also visited during the fieldwork. ized habitats. Relictual species in this region include the
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420 Ambio2015,44:412–425
arapaimaArapaimagigas,oneofthelargestfreshwaterfish Venezuela, and especially Colombia, charging even lower
in the world, of more than two meters in length, the ‘‘aru- prices than Brazil, have increased difficulties for Brazilian
ana˜’’ Osteoglossum bicirrhosum, and the endemic black fishexporters.Inaddition,severalcommonlyexportedfish
‘‘aruana˜’’ O. ferreirai (Petry and Hales 2013). species from the Negro River can now reproduce in cap-
This region is distinguished by the large number of tivity, in the USA and some Asian countries such as
ornamentalfishspeciescapturedtosupplytheinternational Malaysia and Singapore, at reduced costs. Also, the car-
demand for ornamental aquarium fish. The interviewees dinal-tetra, the main species captured in the Negro River,
revealed that there are over 100 commercially exploited isnowundermanagementcontroltoreproduceincaptivity
aquarium species, and the small cardinal-tetra contributes in the USA and the Czech Republic, albeit on a small
over 80% of individuals captured. To compare the local scale.
inspection to satellite images, it was confirmed that the The decline in ornamental fishery is believed to have
forestsofthemidNegroregionarestillverywellpreserved had a negative impact on regional forest conservation. For
and, only recently, with the sharp decline in ornamental example,the ‘‘Piaba Project,’’created by ichthyologist Dr.
fishery, have areas begun to open up for subsistence agri- Labbish Chao, from the University of Amazonas at Man-
culture. One human community visited, Daraqua´, located aus, implies that unlike mining, logging, agriculture, and
inaflooded‘‘igapo´’’area,hadmorethan20familiesabout other activities, ornamental fishing is not a destructive
10yearsago,allrelyingexclusivelyonornamentalfishing. activity. This perception is very clearly expressed in the
With the recent decline in the ornamental fishing trade, slogan of ‘‘Projeto Piaba’’: buy a fish and save a tree.
families were gradually abandoning the community and
moving to land areas where other economic activities are
possible. Therefore, in these new areas, a considerable DISCUSSION
portion of upland forest was removed to accommodate
plantations of cassava, maize, and other crops. Currently, The Amazon’s aquatic ecosystems linked to all biodiver-
only a father and son from one family remain in Daraqua´, sity resources as well as human riverine communities,
where they rely on the capture of ornamental fish. including in many places indigenous peoples who depend
The ‘‘Projeto Piaba’’ (http://opefe.com/piaba.html) is a on natural resources, are increasingly at risk from the
community-based interdisciplinary project established to identified threats here described. Changes in fish species
understand the ecological and sociocultural systems of the composition, alteration of the relative abundances of spe-
Negro basin, in order to conserve and maintain the live cies and their source of food, and changes in reproduction
ornamental fishery and other renewable resources at a and productivities of populations are some of the conse-
commercially feasible and ecologically sustainable level. quencesoftheenvironmentalthreatsandunsustainableuse
According to the interviewees, until around 10 or 12years of fishery resources by humans.
ago, the town of Barcelos had about 600 families relying Natural changes are part of any aquatic ecosystem.
on capture and commerce of ornamental fish. That figure However,presenthumandemographicgrowthandlanduse
has now fallen to less than ten percent of the previous in Amazonia, combined with rapid increases in fishery
number, and the main economic activities have become consumer demands, are bringing new pressures to damage
agricultureandguidingtouristsforsportfishing,especially fish resources and driving more profound changes, more
for‘‘tucunare´s.’’Indeed,nowadaysthesportfishingseason, rapidly than any natural impact has ever done.
whichoccursbetweenAugustandFebruary,iswhatdrives Theidentifiedthreatsontheeffectsofreducedriverflow
the city, both socially and economically. duetodeforestationandinfrastructure(Table4)affectfeeding
Ornamental fishery used to be the main economic and reproductivestrategiesoffish. Infact, the seasonaldis-
activity of the city of Barcelos and other communities of persionoffishtoperformfeedingandreproductionstrategies
the Mid Negro, having started in the mid-twentieth cen- is one of the most striking behavioral complexes of the
tury. It is estimated that, at the time, about 20 million Amazonian ichthyological fauna. The majority of species
ornamental fish were exported every year from Barcelos. move between the river and the adjacent flooded forest,
Differentstakeholdersinterviewedinformedusthatduring including the well-known species such as ‘‘curimata˜’’
the last 10–15years, the entire production chain of orna- Prochilodusnigricans,‘‘jaraquis’’Semaprochilodusspp.,and
mental fish in the Mid Negro River had severely declined. ‘‘pacu’’ Myleus spp. (Batista et al. 2012). The floodplains
The direct and immediate cause of this decline is a sharp supportorganicproductionoftheaquaticecosystemandare
drop in demand for ornamental fish. Indirect causes directlyresponsible for fisheries’ productivity, guaranteeing
underlyingdecreaseindemand,however,arelessclearand fishingyieldsandthemaintenanceofbiodiversity.Inaddition
have multiple origins. Apparently, competition from new tofish-feedingstrategyasafunctionofthefloodingregime,
and growing export markets for ornamental fish in Peru, fish-reproductive strategy depends mainly on the flooded
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Ambio2015,44:412–425 421
season, since the majority of Amazonian fish rely on inun- tide, the waters return to the main river channel, carrying
dated habitats to reproduce. The productivity of the aquatic decaying organic matter, which also contributes to the
ecosystemdependsontwofactors:(1)theamountofnutrients productivity of the aquatic ecosystem. Some fish species,
washeddownbywaterfromtheheadwaters,fromtheAndes, suchasMyleusrhomboidalis,changetheirfeedingstrategy
theBrazilian,andtheGuyanaShields;and(2)fromtheextent depending on the season. During high water they feed on
of the floodplain (lowland flooded forest). Important repre- fruits in the flooded forest. During the dry season, they
sentativesoffishintheseasonallyfloodedaquaticecosystems return to the river and feed on small prey such as inver-
are detritivorous species that feedon decayingplant debris, tebrates (Batista et al. 2012).
followedbyspeciesofherbivores,andfrugivores. The ecological interactions among all the abiotic and
Heterogeneous types of forested riparian vegetation biotic components of the freshwater ecosystem, including
cover about 30% of the Amazon basin (Junk et al. 2014). rivertypes,floodregimes,distinctriparianforest,andmany
The edges or banks of the rivers form a different complex other elements of local biodiversity, are responsible for a
of aquatic habitats, depending on the season of the complex mosaicofaquatic habitats.Animportant aspectto
hydrological cycle. Also the marginal lakes change emphasize is that, depending on the specific water compo-
according to the season of the year, since they have sition, the amount and quality of sediment and nutrients
depressions or passages linking to the main course of the influence primary productivity, fish diversity, and commu-
river. nitystructure.Theseecosystemcomponentsinfluencewater
Seasonalfloodingisoneofthekeyelementsthatcontrol visibilityandelectricconductivity,inconsequenceaffecting
productivity and food webs. The flooded areas create new the behavioral ability of fish to detect visual signals (char-
habitats and the movements of waters carry nutrients that aciformfish)orelectricstimuli(gymnotiformfish)toswim,
supply the food webs. These seasonal forces favor pro- forage, escape from predators, and reproduce.
ductivity,promotingavailabilityofnewaquatichabitatsto However, there is a group of sedentary fish species that
supplyfeedingandreproductivenichesforseveralspecies. are able to stay in the same habitat all year round,
The biogeochemical cycle is an important process con- tolerating a low level of oxygen. This group includes
trolling the productivity of the aquatic ecosystem, com- ‘‘tucunare´s’’ Cichla spp., ‘‘acara´s’’ Geophagus spp.,
bining physical and biological components of the natural ‘‘aruana˜’’Osteoglossumbicirrhosum,‘‘pirarucu’’Arapaima
system. While river dolphins, turtles and fish are able to gigas,variousspeciesof‘‘piranhas’’Serrasalmusspp.,and
respond promptly to the physical component of seasonal Pygocentrusspp.,amongothers(Fabre´andBarthem2005).
flooding,theyarealsointegratedinthebiologicalcomplex The Imazon Deforestation Alert System detected a
of competition and predation, as another component of deforestation area of 838km2 in August and September
trophic linkages. 2014,inAmazonia,whichrepresentsanincreaseof191%
During the beginning ofthe dryseason,whenresources in relation to 288km2 of August–September 2013 (www.
are becoming scarce, many fish migrate into the river imazon.org.br/publication/forest-transparency/deforestation-
channels and change feeding strategy. Therefore, the feed- report-for-the-brazilian-amazon-august-2014-sad). The
ing niches fluctuate depending on water flow. The evolu- impacts on the biogeochemical cycle, as consequences of
tionarystrategiesofvariousfishspeciesvarydependingon clearingandburningoftheAmazonforest,arebeingraised
thefoodsupply:thepredatorpiscivorousspeciessuchasthe as the causes of extreme droughts in southeastern Brazil,
‘‘tucunare´s’’ (Cichla spp.) and the ‘‘pirarucu’’ Arapaima with climate change on broader scales (Cavalcanti 2012).
giga; the carnivores such as the ‘‘acara´’’ Geophagus alti- Flooding or droughts affect the population and several
frons that feed on crustaceans, molluscs, bryozoans and sectors of the economy.
insects; the herbivores that feed on aquatic macrophytes, The effect of hydroelectric dams has a strong influence
such as ‘‘aracus’’ Rhytiodus spp.; the detritivorous species on fish movement and community structure (Table4).
whicharethosethatconsumedecayingorganicmatter,such Some species that exhibit long-distance migration along
as ‘‘jaraquis’’ Semaprochilodusspp.;andtheomnivoresthat rivers, swimming thousands of kilometers upriver to lay
use various sources of food, such as ‘‘tambaqui’’ Colossoma eggs, such as the catfish ‘‘piramutaba’’ Brachyplatystoma
macropomum. vaillanti and ‘‘dourada’’ B. flavicans, find the dam an
There is a synchrony between fruit production in the obstacleintheirmigrationroute(Fabre´andBarthem2005).
inundated forest and the flooding season. Frugivore fish The environmental stimulus that triggers this behavior is a
dispersetothefloodedforesttofeed,suchasspeciesofthe complex set of elements that include water level and tur-
genera Colossoma, Bryconops, Tocantinsia, Leporinus, bidity as well as available seasonal habitat structure. Lotic
Tometes, Myleus and Triportheus. In addition, these spe- environmentofthereservoirreducesrheophilicfishspecies
ciesplayanimportantroleindispersingtheseforestseeds, and favors lentic species such as the phytophagous
contributing to the maintenance of the ecosystem. At low strategists that filter plankton like the ‘‘mapara´s’’
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