aula 2 Flashcards
anthropogenic disturbances types in marine ecosystems
exploitation
physical alteration of habitats
pollutions
bio invasions
global change
multiple stressors
What are the most urgent threats to the
marine (your top 3)? why?
overexploitation - loss of resilience
bio invasions -
multiple stressors -
problems with headlines saying we are in the 6th extinction
strong taxonomic and ecosystem bias (mostly assed for vertebrates and terrestrial domain)
‘…overall decline of 60% in population sizes of vertebrates between 1970
and 2014’ → does not mean that we lost 60% of all animals in 40 years!
marine fauna is in better condition than terrestrial
if we
accelerate the extinction
rates in the ocean, can
the species cope? What do we know so far?
no significant marine species lost ;
species richness maintained
long-term temporal species composition (β diversity) - 10% of the species in each
community change per decade, on average
have we accurately
recorded species
extinctions in the
oceans?
No
-low data
- species dispersal
- research bias
why in the oceans there is low species loss, no change in species richness and only changes of species in each community
- ## local and regional marine assemblages are experiencing a substitution of their taxa: not loss
Biologically sustainable stocks accounted for –% of the 2019
83
The top ten producers account for 57% of the global captures
China, Indonesia,
Peru, India, Russia, USA, Vietnam, Japan, Norway, Bangladesh
Are Sustainable Fisheries Achievable
1- habitat loss / permanent alteration Ex: trawling
2- imperfect science always update an create predictable models (track and predict - but the oceans are less predictable)
3- profit driven minds + manage interests
4- loss of resilience of population
5- altered trophic structures
6- permanent habitat alteration
7-need 4 + clear lines of authority
8- allow fluctuations in yield
9- fishing techniques destructive
10 - manage ilegal uu
11- promote non destructive methods
bycatch problem
difficult detect = poor data
impacts mega fauna and invert
affects food web since the discarded animals are usually dead
trawling effects
- sediment plumes
- sediment biodiversity and communities
- alters geochemical - nutrient cycles…
- frequency affects
how long do systems need to recover from trawling (globally !, not locally…)
only 2 to 7 years are necessary to reach 95% of the carrying capacity of the system, both in biomass and in numbers
most exploited non-living resources in coastal zones
Aggregates (sand and gravel)
diamond deposits
what is the state of seagrass meadows in the world
decreasing globally at a rate of 7% / year
why are seagrass meadows vulnerable
water quality deterioration (nutrients
and sediments)
* pandemic diseases
* destructive fshing practices
* boat propellers and anchors
* coastal development
* cyclones and tsunamis
* aquaculture
* invasive species
* climate chang
